جامعة أم القرى - مذكرة فحص نظر 1 PDF

‫جامعة أم القرى‬ ‫الكلية التطبيقية‬ ‫مذكرة فحص نظر ‪1‬‬ ‫اعداد دكتور ياسر الهمص‬ ‫‪1‬‬ Introduction What's the goal of this c...

‫جامعة أم القرى‬ ‫الكلية التطبيقية‬ ‫مذكرة فحص نظر ‪1‬‬ ‫اعداد دكتور ياسر الهمص‬ ‫‪1‬‬ Introduction What's the goal of this course? The goal of this course is to improve the skills of the ophthalmic technician, both new and experienced. For the new technician, it is important to have a strong base on which to build the foundation of learning. For the experienced technician, it can be valuable to review the basics which may have been neglected with time. This course presumes that thorough history taking does not slow down patient flow, but rather by giving the doctor everything they need prior to seeing the patient, it will streamline the patient’s visit, and prevent the practice from running behind. What is patient history? The definition of patient history In brief, a ‘Patient History’ refers to any information, past or present, that the doctor may find relevant to a patient’s medical care. This will generally include the reason for the visit, medical conditions and current medications, allergies, a review of symptoms, social history, and family history. A well-documented patient history can often provide key pieces of information that the doctor needs to best diagnose and treat their patients. What role does the ophthalmic technician play? In a modern ophthalmic practice, the patient will often spend more time interacting with the ophthalmic technician than the ophthalmologist. It is because of this that the information gathered by the ophthalmic tech is critical to timely and effective patient care. The ability to collect a patient history with speed and accuracy is an important part of a well-run practice. The seven crucial elements of patient history Listed below are the seven things to keep an eye out for when collecting a patient's history. Chief Complaint A chief complaint is a quick summary of why the patient is there. It should include only the most pertinent information about the patient’s reason for the visit. In many cases, the use of electronic medical records (EHR) will in part determine the level of compensation for a visit based on the elements of the 2 chief complaint. Remembering the acronym ‘FOLDAR’ can help complete many of the requirements of EHR. FOLDAR stands for: Frequency – how often does it happen? Onset – when did it start? Location – where is happening/ which eye? Duration – when it happens, how long does it last? Associations – what do you associate with it happening? Remedies – what do you do to improve the symptoms? By asking these series of questions, when applicable, the technician offers the doctor a clear explanation of the patient’s chief complaint while quickly completing the requirements of EHR. Electronic medical records are working to standardize office visits by incentivizing offices to stick to a formula when taking histories. Most of these formulas stem from current Medicare requirements. Currently these software programs are far from uniform, and different EHR software will incentivize different keywords or tests, but there is certain information that most doctors consider necessary when recording a chief complaint. For example, for a diabetic eye exam, the chief complaint should include what type of diabetic they are, how many years the patient has been a diabetic, their most recent fasting blood sugar, their most recent A1c, and what medication or insulin they use to control their blood sugar. When written out, this may look something like this: “Diabetic Eye Exam. DMIIx17 years (Dx 2006), FBS 110, A1c 7.0, Controlled by Metformin” By standardizing the way an ophthalmic technician charts their chief complaint, the doctor will easily know where to find the information they’re looking for. Another common reason for a follow-up visit will be for glaucoma. Glaucoma visits should include the type of glaucoma the patient has (when known), any glaucoma medications they are taking and how often, the last time that medication was taken, and any side effects they may be experiencing. A standardized visit for a glaucoma follow-up may look something like this: “Four month follow-up for POAG, Pt states compliance with Latanoprost OU QHS (last taken 930pm). Pt reports increased dry eye associated with gtts” 3 Lastly, most doctors want a chief complaint to include some mention of the patient’s vision. A patient’s perception of how well they see can tell a doctor a lot about how the patient is doing overall. If a patient has less than perfect vision, but feels they are functioning well with no complaints, a doctor would probably not recommend cataract surgery. On the other hand, a patient with relatively good Snellen acuity who feels highly symptomatic may be a candidate. This is why including a subjective assessment of vision in the chief complaint is valuable. Medical Conditions How a technician gathers a patient’s medical conditions will differ from practice to practice. Some offices have patients fill out their own forms, in which case the technician would just transfer what the patient has responded into the electronic medical records, while other practices will have the technician ask the patient directly. Patients will often be dismissive when asked about medical problems or changes in their medical history. Rather than posing the question as “changes in their history,” the technician should reassure them that they are confirming that the office’s records are accurate. Rather than asking the broad question, “has anything changed since we last saw you?” ask a more direct question like, “We last saw you May 24 of 2018. Since that time, have you had any surgeries or hospitalizations?” This adds the context of a date, and asking about specific events will garner better results. Medications Similar to medical history, the patient may try to expedite the technician’s line of questioning by stating that “nothing has changed.” Keep the conversation open by continuing the pretense of “checking that the office’s records are accurate for the patient.” The technician can say, “We currently have you taking five medications,” and then list those medications for the patient. The patient may feel certain medications are not relevant to the eyes, but a large number of medications unrelated to eyes, from antidepressants to prostate medications, cause ocular side effects which makes knowing that the patient is taking them important. Even nonprescription medications like vitamins, such as fish oil or flaxseed, can have ocular side effects. Allergies 4 The purpose of knowing a patient’s allergies is to avoid interaction. Along with knowing a patient’s allergies, it can be valuable to know if the patient has had any adverse reactions to medications that may not qualify as true ‘allergies.’ This will be covered in greater detail in a later module on history taking. Review of Symptoms (ROS) A review of symptoms is a list of questions that are asked specifically about symptoms the patient is currently experiencing, like chest pain or joint pain. It may seem very similar to ‘medical problems’ and in some ways it is, but the key difference is a review of symptoms highlights the patient’s perception of their health. The ophthalmic technician can use the review of symptoms to ask better questions relating to medical history or medications. Social History Just as medical conditions and medications affect the eyes, lifestyle plays a role in ocular health. For example, it is important to ask patients about their smoking status, as nicotine weakens the vascular structure, and the eyes are comprised of small blood vessels. Employment status and hobbies are also important, as different professions will have different visual needs. Even what a patient did for work before they retired can be valuable, as patients who worked outside their entire working life are more likely to develop pterygiums, cataracts at a younger age, and macular degeneration. Family History Many medical conditions are hereditary, so asking about family history is important. It is more helpful to ask direct questions rather than vague ones. Rather than “Do you have a history of eye disease in your family?” it will be more successful to ask, “Do your parents, or did your grandparents, have macular degeneration, glaucoma, or other eye conditions?” How to take patient history Getting all the info Collecting Information Every office will have their own system for collecting patient history, some offices will use forms that the patients will fill out themselves and then hand in to have scanned or transferred into the electronic medical record, but 5 increasingly it is becoming the technician’s job to record the patient’s medical conditions, medications, allergies, social, and family histories. This means its critical that the technician asks the correct questions to get the information the doctor will need to properly treat the patient. Connecting with patients Having a connection with the patient is the easiest way to gather accurate information quickly, but making that connection is not always easy. Mirroring the patient’s tone or body language will make them feel more comfortable. The technician should always introduce themselves and explain the role that they will be playing in the patient’s care. Asking the patient about what they do for work, what hobbies they have, or what they did prior to retirement can aid both in learning about social history and visual needs, but can also help disarm the patient and keep them at ease. Questions to ask Knowing the right questions to ask is another key to quick and accurate history taking. How a question is asked is often as important as what is being asked. Many patients self-omit parts of their history that they deem unrelated to the reason for their visit, or they require prompting to be reminded. When asking about medical history, rather than asking an easily dismissed question such as, “Do you have any medical conditions?” ask direct questions like, “Do you have diabetes, high blood pressure, or high cholesterol?” The technician can then broaden the question to “Do you have any other medical conditions?” Giving the patient time to think will often help them explain their conditions in greater detail and lead to great success in history taking. Most offices will request patients bring a list of medications with them to every visit, but invariably there will be patients who do not. In those cases, it’s important that the technician does their best to create as complete a list as possible by asking pointed questions like “Do you take any vitamins or supplements? Do you know what they're called?” Once their Medical History has been established, the patient can be asked directly if they can remember the names of any of the medications for each medical condition. Rather than simply asking a patient if they’re allergic to anything, ask them “Are you allergic to any medication, or are there any medications that you avoid taking because they make you sick or uncomfortable?” Broadening the question 6 may help the patient remember a specific incident where a medication made them ill. When the form isn’t enough Although many offices give the patient these forms to fill out themselves, there will always be a need for clarification and expansion by the ophthalmic technician. By knowing how to ask the proper direct questions, the technician can keep the patient’s medical history complete and accurate. Effectively communicating with patients Patient communication and education What is your role? It is the role of the ophthalmic technician to prepare the patient for the doctor, complete any ancillary testing that has been ordered, instruct the patient on their medication usage, schedule and assist in procedures, and maintain patient flow through the day. There are often other administrative tasks that may be required of the ophthalmic technician, but in short, the role of the ophthalmic technician is to aid the doctor. Explaining medications and treatments One of the many ways the ophthalmic technician assists the doctor is in educating the patient on basic instructions after the patient’s exam is complete. Any time a patient is given a new medication, it is important to review any possible side effects with the patient prior to them leaving the office. If the side effects are temporary, give the patient a timeline that they should expect to experience them. Educated patients are more compliant. When performing an ancillary test, such as an OCT or a visual field, take a moment to instruct the patient as to why the test was ordered, the purpose of the test, and what the patient’s role will be. Even if a patient has completed a visual field once every six months for a decade, they should not be required to remember what they are supposed to do. The ophthalmic technician should explain the test to the patient every time they administer it as if the patient has never completed the test before to avoid confusion. 7 Never ask a patient to sign a consent for a procedure without giving them time to read it first. If the patient is going to take too long, or will struggle with reading it on their own, the consent needs to be read to them. The ophthalmic technician should ask the patient at least twice if they have any questions, and refer those questions to the doctor if necessary. Discussing the patient’s questions with them in a rhetorical setting may seem redundant, but the purpose is to help the patient articulate their questions more concisely, so when they speak with the doctor they ask questions that best represent the concerns they actually have. Anticipating need Preparing the patient to see the doctor means three key things: 1. First, it means taking a thorough and accurate history. 2. Second, it means to identify with the patient any questions the patient may have and answer them or defer to the doctor. 3. Lastly, the ophthalmic technician must anticipate the needs of the doctor once they’re in the room. If the patient is in the office to have a procedure, that means preparing the room for said procedure, and printing a consent form when applicable. If the patient in due for ancillary testing, it is the job of the technician to complete the testing prior to the doctor seeing the patient, so everything is available for review when the doctor walks through the door. Anticipating need can be one of the most difficult parts of being an ophthalmic technician, but it can also save the most time. Preparing patients to see the doctor Communicating patient history to your doctor Although the ophthalmic technician spends a great deal of time crafting a concise and thorough patient history, the doctor, upon entering the exam room, may not fully read it. That is not to say it isn’t valuable; the patient history is still extremely valuable, as it will be referred back to in the future. However, because the doctor may not have time to read it over fully, the technician has to develop ways to highlight relevant information for the doctor so it is not overlooked. 8 What to flag Every office develops its own way of informing the doctor of key information that may be overlooked in a standard exam. Sometimes a simple note on the front of a chart can alert the doctor to come speak to a technician before going into the exam room. Other times, with electronic medical records, having a pop up alert the doctor may be more useful. Knowing how to alert the doctor is one thing—knowing what to alert them of is another. As stated before, the ophthalmic technician interacts with the patient first, and often for a longer period of time than the ophthalmologist. If a patient is nervous, or combative, the technician is going to perceive that, and should absolutely communicate that to the doctor so they can be prepared. If a patient has recently been diagnosed as a diabetic, the technician may want to print out education on diabetic eye disease so the doctor sees it upon entering the room and can spend extra attention on discussing the importance of managing their diabetes. If the patient has a question that would be best fielded by the doctor, instruct the patient to ask the doctor directly. Depending on the nature of the question, it may be helpful to tell the patient to ask the doctor at the beginning of the exam, or save the question for the end. The technician should let the patient know their question has been written down, but it will be more valuable to the doctor to hear the question directly from the patient. Thinking on your feet There will always be situations which fall outside the normal scope of history taking, and in those times, the ophthalmic technician should be prepared to be flexible. Flexibility may be as simple as taking in a patient who has an appointment later on the schedule because they have arrived early, and the technician knows their appointment will take extra time. The ability to use clinical judgement or anticipate need is a skill that develops with experience. When venturing outside the normal routine, the technician should check in with the doctor afterwards to get feedback. This will both let the doctor know there was thought behind the actions taken, and will assist the technician in knowing if they should do the same thing in the future. 9 How to take a complete eye history Moureen Takusewanya Additional article information Taking a good history not only helps you to make a diagnosis, it can also help you to understand the impact of the condition on the patient and identify any obstacles to treatment. Open in a separate window Make careful notes when you take a history. SOUTH SUDAN 10 It is impossible to over-emphasise the importance of taking a careful history when assessing an eye patient. Taking a good history can help to focus your examination and indicate what investigations are needed. It can also help you to understand the impact of the condition on the patient and pinpoint any difficulties they may have adhering to treatment. This is also your opportunity to focus on the patient as a person and to form a relationship of trust, respect and mutual understanding. How to structure history taking To ensure you don't miss anything important, structure your history taking carefully. Ask about: Personal and demographic data Reason for visit or presenting complaint History of presenting complaint Past eye history General medical history Family eye history Medication history Allergy history Social history Tip: You can use this bulleted list as a checklist Copy and keep it where you can see it during history taking to help you to stay on track and ensure that you will not miss anything important. Each of these is discussed in more detail below. Top tips for taking a good history Introduce yourself to the patient – this creates a friendly environment. Respect the patient's privacy and confidentiality while taking the history Ask questions that are direct, simple and clear. Avoid using medical terms and explain things in ordinary language as much as possible. Be a good listener. Avoid interrupting or rushing the patient. Show them that you are listening and paying attention: make eye contact as appropriate and ask if you are not sure about something they said. It is often useful to use open questions (e.g., how are you?) and closed questions (e.g., yes/no answers) to help focus the discussion. Try to see things from the patient's point of view and make an effort to understand them and their circumstances, especially when these are very different from your own. Be aware that patients who are older, or who have disabilities (including hearing impairment, speech difficulties or a learning disability) may need a bit more time or 11 may struggle to express themselves. This may cause them some anxiety, so remain patient and reassure them that you are there to listen. Personal and demographic data Ask the patient's personal details: Name, for identification, filing and patient follow-up Address and mobile phone number, for follow-up and to identify patients from areas with endemic diseases Age and gender, for noting down and ruling out any diseases associated with different age groups and/or sex Language Disability Patient's occupation, daily tasks and hobbies. Recording the age, gender, language and disability status of patients allows you to monitor who is, and is not, coming to your eye clinic or hospital. Compare these figures with the population to identify groups that are under-represented, e.g., girls with other disabilities, and plan ways to reach out to them. Understanding a patient's occupation, daily tasks (e.g., looking after grandchildren) and hobbies is helpful for finding out a patient's visual needs and understanding any eye manifestations or symptoms as a result of occupational hazards. Reason for visit/Presenting complaint Ask the main reason why the patient has come to seek an eye examination. Record the main presenting symptoms in the patient's own words and in a chronological order. The four main groups of symptoms are: 1. Red, sore, painful eye or eyes (including injury to the eye) 2. Decreased distance vision in one or both eyes, whether suddenly or gradually 3. A reduced ability to read small print or see near objects after the age of 40 years 4. Any other specific eye symptom, such as double vision, swelling of an eyelid, watering or squint. History of presenting complaint This is an elaboration of the presenting complaint and provides more detail. The patient should be encouraged to explain their complaint in detail and the person taking history 12 should be a patient listener. While taking a history of the presenting complaint, it is important to have potential diagnoses in mind. For each complaint, ask about: Onset (sudden or gradual) Course (how it has progressed) Duration (how long) Severity Location (involving one or both eyes) Any relevant associated symptoms Any similar problems in the past Previous medical advice and any current medication. Past eye history Ask for detail about any previous eye problems History of similar eye complaints in the past. This is important in recurrent conditions such as herpes simplex keratitis, allergic conjunctivitis, uveitis and recurrent corneal erosions History of similar complaints in the other eye is important in bilateral conditions such as uveitis, cataract History of past trauma to the eye may explain occurrence of conditions such as cataract and retinal detachment History of eye surgery. It is important to ask about any ocular surgery in the past such as cataract extraction, muscle surgery, glaucoma, or retinal surgery Other symptoms. Ask whether the patient has any other specific eye symptoms. General medical history Ask about any current and past medical conditions. These include conditions such as diabetes, hypertension, arthiritis, HIV, asthma and eczema. Family eye history It is important to ask the patient whether any other member of the family has a similar condition or another eye disease. This can help to establish familial predisposition of inheritable ocular disorders like glaucoma, retinoblastoma or congenital eye diseases, diabetes and hypertension. 13 Medication history Ask about present and past medications for both ocular and medical conditions. Don't overlook any medications that the patient may have stopped taking some time ago. Some medications are important in the etiology of ocular conditions. It is also helpful to ask whether the patient has been able to use the medication as prescribed (their compliance). If a medication is ineffective, you want to know whether the patient is actually using the medication as prescribed, for example glaucoma medications. Using your own discretion, it is helpful to find out whether access to medication prescribed is a problem. This helps to ascertain whether cost or other concerns are a potential reason for non-compliance. There could also be practical issues, such as difficulty instilling eyedrops or forgetting to do so. Do not forget to ask in a non-judgmental way about traditional/herbal medication use. 14 Figure 1 15 16  Open in a separate window Case scenarios with different presenting complaints Allergies Ask about any allergies to medications or other substances. Social history Smoking (amount, duration and type) Alcohol (amount, duration and type) Birth and immunisation history For children, the birth history (prematurity) and immunisation status can be important. Parts of the Eye Here I will briefly describe various parts of the eye: Sclera The sclera is the white of the eye. "Don't shoot until you see their scleras." Exterior is smooth and white Interior is brown and grooved Extremely durable Flexibility adds strength Continuous with sheath of optic nerve Tendons attached to it The Cornea The cornea is the clear bulging surface in front of the eye. It is the main refractive surface of the eye. Primary refractive surface of the eye Index of refraction: n = 1.37 17  Normally transparent and uniformly thick Nearly avascular Richly supplied with nerve fibers Sensitive to foreign bodies, cold air, chemical irritation Nutrition from aqueous humor and Tears maintain oxygen exchange and water content Tears prevent scattering and improve optical quality Anterior & Posterior Chambers The anterior chamber is between the cornea and the iris The posterior chamber is between the iris and the lens Contains the aqueous humor Index of refraction: n = 1.33 Specific viscosity of the aqueous just over 1.0 (like water, hence the name) Pressure of 15-18 mm of mercury maintains shape of eye and spacing of the elements Aqueous humor generated from blood plasma Renewal requires about an hour Glaucoma is a result of the increased fluid pressure in the eye due to the reduction or blockage of aqueous from the anterior to posterior chambers. Iris/Pupil Iris is heavily pigmented Sphincter muscle to constrict or dilate the pupil Pupil is the hole through which light passes Pupil diameter ranges from about 3-7 mm Area of 7-38 square mm (factor of 5) Eye color (brown, green, blue, etc.) dependent on amount and distribution of the pigment melanin Lens Transparent body enclosed in an elastic capsule Made up of proteins and water 18  Consists of layers, like an onion, with firm nucleus, soft cortex Gradient refractive index (1.38) Young person can change shape of the lens via ciliary muscles Contraction of muscle causes lens to bulge At roughly age 50, the lens can no longer change shape Becomes more yellow with age: Cataracts The graph on the right shows the optical density (-log transmittance) of the lens as a function of wavelength. The curves show the change in density with age. More short wavelength light is blocked at increases ages. Vitreous Humor Fills the space between lens and retina Transparent gelatinous body Specific viscosity of 1.8 - 2.0 (jelly-like consistency) Index of refraction, n=1.33 Nutrition from retinal vessels, ciliary body, aqueous Floaters, shadows of sloughed off material/debris in the vitreous Also maintains eye shape Retina 19  Notice the orientation of the retina in the eye. The center of the eyeball is towards the bottom of this figure and the back of the eyeball is towards the top. Light enters from the bottom in this figure. The light has to pass through many layers of cells before finally reaching the photoreceptors. The photoreceptors are where the light is absorbed and transformed into the electrochemical signals used by the nervous system. This change is calledTRANSDUCTION. The interior of the eyeball is the "inner" side and the exterior is the "outer" side. The nuclear layers contain cell bodies. The plexiform layers contain the connections between cells in the retina. This next picture shows a schematic of the cells in the retina: 20 Again the light in entering from the bottom passing through all these layers before being absorbed in the receptors. You can see the two types of receptors: the rod-shaped rods and the cone-shaped cones. The signal, after transduction, is passed to the horizontal cells (H) and the bipolar cells via a layer of connections. Lateral processing takes place in this layer via the horizontal cells. The throughput is transferred to another layer of connections with the amacrine cells (A) and the ganglion cells. The amacrine cells also exhibit lateral connections in this inner plexiform layer. The signals pass out of the eye via the ganglion cell axons which are bundled together to form the optic nerve. The retina has a similar layered structure as the gray-matter top layers of the cerebral cortex of the brain. In fact, the retina is an extension of the central nervous system (the brain and spinal cord) that forms during embryonic development. This is one reason why scientists are interested in retinal processing; the retina is an accessible part of the brain that can be easily stimulated with light. Speaking of the optic nerve... The location where the optic nerve is bundled and leaves the retina is known as the optic disk. There are no photoreceptors at the location of the optic disk and hence there is a blind spot. The scientific term for a blind spot is a scotoma. So the blind spot due to the optic disk is a natural permanent scotoma in normal vision. Here is a demonstration of the natural permanent scotoma: 21 Close your left eye. Fixate on the cross with your right eye. This will cause the image of the cross to fall on your fovea. Adjust the viewing distance until the black spot disappears. When this happens, the image of the spot is falling on your blind spot. What do you see (or not see) when you do this with the top figure? What happens when the gap in the bottom figure falls on your blind spot? 22 You should see the "smiley" in the top figure disappear when it falls in your blind spot. When the gap in the bottom figure falls on the blind spot, the visual system "fills in" the line. So why don't we notice the blind spot in normal vision? For one, we have two eyes and the blind spots are in non-corresponding locations (they are nasally located (towards the nose) on the retina so the blind spots are temporal (towards the temple) in the visual field). In addition, the filling in process makes the blind spot less noticeable especially in a peripheral area of sight that has less visual acuity (the ability to see detail). As mentioned above, in front of the receptors are layers of cells through which the light must pass. In addition there is vasculature on the front surface of the retina. You can see this vasculature (or more correctly its shadow) by pressing a pen light to the side of your eyeball and gently wiggling it. What you will see looks like the figure below. Why don't we see this regularly? As mentioned previously, the visual system is sensitive to change and when the light enters normally through the pupil, the vessels are stable. They are also small and narrow so they do not block much light however when illuminated from the side they cast a wider shadow. If you look at a deep blue field or up at the sky (not the sun) on a clear day, you may notice pulsations or squiggles moving around. These are the shadows of the red corpuscles in the blood in these vessels. The Fovea The fovea is the location on the retina of central gaze. When you look directly, or fixate, at a stimulus you the retinal locus of this central fixation is the fovea. There are only cones in the human fovea (no rods). They are thinner, elongated, any very tightly packed. Because of this, the fovea is the location of highest visual acuity and best color vision. 23 In the diagram below you can see that the retinal layers are pulled aside (the axons of the receptors are elongated) leaving a clearer path for the light to reach the receptors. There is actually a little indentation or pit at the location of the fovea due to this and it is a clear landmark in the retina during an ophthalmic examination. The elongated outer segments of the cones (where the photopigment is and where the transduction occurs) increase the sensitivity by increasing the amount of photopigment. There is no vasculature in the central fovea. The Macula Covering the fovea is a pigment called the macula. it is thought that the macula serves as a protective filter over the foviea that absorbs blue and ultraviolet radiation. This pigment varies from observer to oberver and is a source of individual variation in color vision. 24 Another demonstration of the macula is called Haidinger's Brushes. Look at a uniform blue field (again the clear sky works well for this) through a linear polarizer. You may be able to see a small yellow hourglass in the central 3° area. As you change the orientation of the polarizer, the orientation of the hour glass changes. To the right is an artists depiction of Haidinger's Brushes. The Ophthalmoscope OK, the ophthalmoscope is not a part of the eye... If you want to see into someone's eye you have a problem. Your head will block the light entering the eye. Attributed to Helmholtz, the ophthalmoscope solves this problem by shining a small beam of light in to the eye. The reflected light is then available for viewing. This is a schematic diagram showing how an ophthalmoscope works. An alternative is to use a half silvered mirror that covers the complete entrance area and allows half the light ener the eye and then allows half of the reflecting light to pass through the mirror into the observers eye. In class, I try to borrow an ophthalmoscope so that the students can look into each other's eyes. Perhaps you can get hold of one or ask your physician or eye doctor to let you try it on him/her. 25 One other time that one sees the inside of the eye is when you get red-eye in a photograph. What you see here is the reflection off the retina of the rhodopsin, the pink colored photopigment in the rod photoreceptors. 26  Almost the whole of the interior of the spherically-shaped eyeball is lined with a layer of photosensitive cells known collectively as the retina and it is this structure that is the sense organ of vision. The eyeball, though no mean feat of engineering itself, is simply a structure to house the retina and to supply it with sharp images of the outside world. Light enters the eye through the cornea and the iris and then passes through the lens before striking the retina. The retina receives a small inverted image of the outside world that is focused jointly by the cornea and the lens. The lens changes shape to achieve focus but hardens with age so that we gradually lose our accommodation. The eye is able to partially adapt to different levels of illumination since the iris can change shape to provide a central hole with a diameter between 2mm (for bright light) and 8mm.)(for dim light 27 Your eye works like a camera. The white part on the outside of the eyeball is called the sclera. In its center is the cornea, the transparent part of the eye that covers the iris or colored part of the eye. The iris operates like a camera shutter by controlling the amount of light that enters the eye. Located behind the iris is the eye lens. It is suspended by fibers that tighten or loosen to focus the light rays from objects outside the eye onto the retina, located at the back of the eye. ?How Does The Human Eye Work The individual components of the eye work in a manner similar to a camera. Each part plays a vital role in providing clear vision. So think of the eye as a camera with the cornea, behaving much like a lens cover. As the eye’s main focusing element, the cornea takes widely diverging rays of light and bends them through the pupil, the dark, round opening in the center of the colored iris..The iris and pupil act like the aperture of a camera Next in line is the lens which acts like the lens in a camera, helping to focus light to the back of the eye. Note that the lens is the part which becomes cloudy and is removed during cataract surgery to be replaced by an artificial implant nowadays. 28  The Camera The Human Eye 29 30 The muscles of the orbit are a group of six muscles that control movement of the eye. Four of the muscles control the movement of the eye in the four cardinal directions: up, down, left and right. The remaining two muscles control the adjustments involved in counteracting head movement; for instance this can be observed by looking into ones own eyes in a mirror whilst moving ones head. Primary Secondary Tertiary Muscle Innervation function function function Superior Oculomotor Intorsion ‫دوران‬ Elevation Adduction rectus nerve ‫للداخل‬ Inferior Oculomotor Extorsion ‫دوران‬ Depression Adduction rectus nerve ‫للخارج‬ Abducens Lateral rectus Abduction ‫ إبعاد‬.. nerve Oculomotor Adduction ‫إلى‬ Medial rectus.. nerve ‫الداخل‬ Superior Depression Trochlear nerve Intorsion Abduction oblique ‫انخفاض‬ Inferior Oculomotor Extorsion Elevation ‫رفع‬ Abduction oblique nerve A good mnemonic to remember which muscles are innervated by Lateral Rectus - Cranial Nerve VI, Superior Oblique - Cranial Nerve IV, the Rest of the muscles - Cranial Nerve III. Purpose The motor apparatus, precisely and rapidly, controls eye movement for exact alignment with the fovea, since this is the area that deals with sharp vision. 31  This swift and accurate motion is evident in reading. When keeping the gaze on a small object, like a golf ball, the eyes must compensate for the small movements of the head to keep the object on the fovea. The eyes can be controlled by voluntary means, as one can deliberately change focus. However, most eye movement is done without awareness. This is evident when viewing moving objects or head or body movement. Studying the movements of the eyes depend on reflexes brought on by factors in the environment or the individual, keeping in mind the voluntary control. NOTE: The functions of the rectus and oblique muscles in the table on this page "Muscles of Orbit" contradicts this section of text and the page "Extraoccular Muscles" and need to be edited. Clinical Examination The initial clinical examination of the extraoccular eye muscles is done by examining the movement of the globe of the eye through the six cardinal eye movements. When the eye is turned in (nasally) and horizontally, the function of the medial rectus muscle is being tested. When it is turned out (temporally) and horizontally, the function of the lateral rectus muscle is tested. When turning the eye down and out, the inferior rectus is contracting. Turning the eye up and out relies on the superior rectus. Paradoxically, turning the eye up and in uses the inferior oblique muscle, and turning it down and in uses the superior oblique. All of these six movements can be tested by drawing a large "H" in the air with a finger or other object in front of a patient's face and having them follow the tip of the finger or object with their eyes without moving their head. Having them focus on the object as it is moved in toward their face in the midline will test convergence, or the eyes' ability to turn inward simultaneously to focus on a near object. The extraocular muscles, considering their relatively small size, are incredibly strong and efficient. There are the six extraocular muscles, which act to turn or rotate an eye about its vertical, horizontal, and antero-posterior axes: 1. medial rectus (MR), 32  2. lateral rectus (LR), 3. superior rectus (SR), 4. inferior rectus (IR), 5. superior oblique (SO), and 6. inferior oblique (IO). Here is a schematic of a left eye, showing how its extraocular muscles insert into the eye: muscle movements A given extraocular muscle moves the pupil, at the front of the eye, in a specific direction or directions, as follows: medial rectus (MR)— o moves the eye inward, toward the nose (adduction) lateral rectus (LR)— o moves the eye outward, away from the nose (abduction) superior rectus (SR)— o primarily moves the eye upward (elevation) o secondarily rotates the top of the eye toward the nose (intorsion) o tertiarily moves the eye inward (adduction) inferior rectus (IR)— o primarily moves the eye downward (depression) o secondarily rotates the top of the eye away from the nose (extorsion) o tertiarily moves the eye inward (adduction) superior oblique (SO)— o primarily rotates the top of the eye toward the nose (intorsion) o secondarily moves the eye downward (depression) o tertiarily moves the eye outward (abduction) inferior oblique (IO)— o primarily rotates the top of the eye away from the nose (extorsion) o secondarily moves the eye upward (elevation) 33  o tertiarily moves the eye outward (abduction) The primary muscle that moves an eye in a given direction is known as the “agonist.” A muscle in the same eye that moves the eye in the same direction as the agonist is known as a “synergist,” while the muscle in the same eye that moves the eye in the opposite direction of the agonist is the “antagonist.” According to “Sherrington’s Law,” increased innervation to any agonist muscle is accompanied by a corresponding decrease in innervation to its antagonist muscle(s). cardinal positions of gaze The “cardinal positions” are six positions of gaze which allow comparisons of the horizontal, vertical, and diagonal ocular movements produced by the six extraocular muscles. These are the six cardinal positions: up/right up/left right left down/right down/left In each position of gaze, one muscle of each eye is the primary mover of that eye and is yoked to the primary mover of the other eye. Below, each of the six cardinal positions of gaze is shown, along with upward gaze, downward gaze, and convergence: MR = Medial Rectus LR = Lateral Rectus 34  SR = Superior Rectus IR = Inferior Rectus SO = Superior Oblique IO = Inferior Oblique muscle innervations Each extraocular muscle is innervated by a specific cranial nerve (C.N.): medial rectus (MR)—cranial nerve III (Oculomotor) lateral rectus (LR)—cranial nerve VI (Abducens) superior rectus (SR)—cranial nerve III (Oculomotor) inferior rectus (IR)—cranial nerve III (Oculomotor) superior oblique (SO)—cranial nerve IV (Trochlear) inferior oblique (IO)—cranial nerve III (Oculomotor) The following can be used to remember the cranial nerve innervations of the six extraocular muscles: LR6(SO4)3. That is, the lateral rectus (LR) is innervated by C.N. 6, the superior oblique (SO) is innervated by C.N. 4, and the four remaining muscles (MR, SR, IR, and IO) are innervated by C.N. 3. anatomical arrangement All of the extraocular muscles, with the exception of the inferior oblique, form a “cone” within the bony orbit. The apex of this cone is located in the posterior aspect of the orbit, while the base of the cone is the attachment of the muscles around the midline of the eye. The apex of the conic structure is a tendonous ring called the “annulus of Zinn.” Through the annulus, and along the middle of the cone of muscles, runs the optic nerve(cranial nerve II). Within the optic nerve are contained the ophthalmic artery and the ophthalmic vein. The superior oblique, although part of the cone of muscles, differs from the other muscles in a significant way. Before it attaches to the eye, it passes through a ring-like tendon, the “trochlea,” in the nasal portion of the orbit. The trochlea acts as a pulley for the superior oblique muscle. The inferior oblique, which is not a member of the cone of muscles originating from annulus of Zinn, arises from the lacrimal fossa in the nasal portion of the bony orbit. This muscle attaches to the inferior portion of the eye. 35 ductions When considering each eye separately, any movement is called a “duction.” Describing movement around a vertical axis, “abduction” is a horizontal movement away from the nose, caused by a contraction of the LR muscle, with an equal relaxation of the MR muscle. Conversely, “adduction” is a horizontal movement toward the nose, caused by a contraction of the MR muscle, with an equal relaxation of the LR muscle. Describing movement around a horizontal axis, “supraduction” (elevation) is a vertical movement upward, caused by the contraction of the SR and IO muscles, with an equal relaxation of the of the IR and SO muscles. Conversely, “infraduction” (depression) is a vertical movement downward, caused by the contraction of the IR and SO muscles, with an equal relaxation of the SR and IO muscles. Describing movement around an antero-posterior axis, “incycloduction” (intorsion) is a nasal or inward rotation (of the top of the eye), caused by the contraction of the SR and SO muscles, with an equal relaxation of the IR and IO muscles. Conversely, “excycloduction” (extorsion) is a temporal or outward rotation (of the top of the eye), caused by the contraction of the IR and IO muscles, with an equal relaxation of the SR and SO muscles. versions When considering how the eyes work together, a “version” or “conjugate” movement involves simultaneous movement of both eyes in the same direction. Agonist muscles in both eyes, which work together to move the eyes in the same direction, are said to be “yoked” together. According to “Hering’s Law,” yoked muscles receive equal and simultaneous innervation. There are six principle versional movements, where both eyes look or move together in the same direction, simultaneously: dextroversion (looking right)— o right lateral rectus o left medial rectus levoversion (looking left)— o left lateral rectus o right medial rectus supraversion or sursumversion (looking straight up)— o right & left superior recti o right & left inferior obliques infraversion or deorsumversion (looking straight down)— o right & left inferior recti o right & left superior obliques 36  dextroelevation (looking right and up)— o right superior rectus o left inferior oblique dextrodepression (looking right and down)— o right inferior rectus o left superior oblique levoelevation (looking left and up)— o right inferior oblique o left superior rectus levodepression (looking left and down)— o right superior oblique o left inferior rectus dextrocycloversion (rotation to the right)— o right inferior rectus & inferior oblique o left superior rectus & superior oblique levocycloversion (rotation to the left)— o left inferior rectus & inferior oblique o right superior rectus & superior oblique vergences A “vergence,” or “disconjugate” movement, involves simultaneous movement of both eyes in opposite directions. There are two principle vergence movements: convergence—both eyes moving nasally or inward divergence—both eyes moving temporally or outward If one eye constantly is turned inward (“crossed-eye”), outward (“wall-eye”), upward, or downward, this is referred as a “strabismus” or “heterotropia,” discussed later. Usually, a vergence is performed relative to a point of fixation. For instance, someone could be looking at TV across the room (at a far distance). Then, when a commercial comes on, that person could converge both eyes to read a book (at a near distance). Then, after the commercial is over, both eyes would diverge to look at the TV again. One cannot actually voluntarily diverge both eyes outward, at the same time, from looking straight ahead. That is, the two lateral recti muscles cannot pull the eyes outward, simultaneously and voluntarily, while one is viewing something far away. However, if one is falling asleep with one’s eyes still open, it is possible for the eyes to diverge, momentarily and involuntarily, causing temporary diplopia (double vision). strabismus (heterotropia) 37 Normally, when viewing an object, the “lines of sight” of both eyes intersect at the object; that is, both eyes point directly at the object being viewed. An image of the object is focused upon the macula of each eye, and the brain merges the two retinal images into one. Sometimes, however, due to some type of extraocular muscle imbalance, one eye is not aligned with the other eye, resulting in a “strabismus,” also called a “heterotropia” or simply a “tropia.” Occasionally, this ocular deviation is referred to as a “squint,” although this term is not very descriptive and no longer is commonly used. With strabismus, while one eye is fixating upon a particular object, the other eye is turned in another direction, relative to the first eye, whether inward (“cross-eyed”), outward (“wall-eyed”), upward, or downward. As a result, the person may experience “diplopia” (double vision), since two different objects are imaged onto the maculas of both eyes. However, if the person’s brain has learned to “suppress” (turn off) the image of the strabismic (turning) eye, the brain will perceive only the single image from the other eye. If the strabismus occurs sometimes, but not all of the time, it is said to be “intermittent.” If the strabismus occurs all of the time, it is said to be “constant.” Occasionally, whether the strabismus is intermittent or constant, one eye will be the deviating eye at certain times, while the opposite eye will be the deviating eye at other times. That is, one eye will turn sometimes, but at other times the alternate eye will turn. This is referred to as “alternating” strabismus. The misalignment of a strabismic eye occurs in about 2% of children. The deviant eye may be in any direction: inward (“esotropia” or “crossed-eye”), outward (“exotropia” or “wall-eye”), upward (“hypertropia”), downward (“hypotropia”), or any combination of these. Strabismus also can occur due to a nerve paralysis or paresis, injury, or even due to a retinal disease. Sometimes a strabismus will result when there is a very different refractive error (usually much higher) in the strabismic eye compared to the other eye. The angle of deviation of the strabismus is measured in “prism diopters.” If the angle of deviation remains the same in all cardinal positions of gaze, the strabismus is classified as “concomitant” (or “nonparalytic”). If the angle of deviation is not the same in all cardinal positions of gaze, the strabismus is classified as “nonconcomitant” (or “paralytic”). Below, views of the two most common types of strabismus—esotropia and exotropia— are displayed: 38  OD (Right Eye) Esotropia OD (Right Eye) Exotropia Esotropia can be congenital (a muscle imbalance present from birth), and usually the angle of deviation is large. Management involves surgical correction, typically at age six months or earlier. Some cases of low-angle esotropia do not require surgery but, instead, respond successfully to visual therapy. This is true especially in a child or an adult for which the esotropia is of recent onset and for which there is no macular damage (that is, when the strabismic eye is capable of good visual acuity). The esotropia also can be accommodative, usually due to a high amount of uncorrected hyperopia (farsightedness). This causes a great deal of accommodation to be required to focus retinal images, resulting in a subsequent over-convergence (by the medial rectus muscles) and a subsequent esotropia. The usual treatment for accommodative esotropia is eyeglasses or contact lenses, which compensate for the hyperopia, allowing the deviating eye to straighten. Exotropia also can be congenital, although this is very unusual. More commonly, exotropia develops in infancy or in early childhood, often beginning as an intermittant (occasional) strabismus and sometimes leading to a constant strabismus. A carefully planned regimen of visual therapy often can be used to treat exotropia, especially in cases where complete suppression of the strabismic eye has not yet occurred and the eye is capable of good visual acuity. However, in cases where visual therapy is not successful, surgical correction should be used to provide a cosmetically improved appearance of the deviating eye. This does not necessarily ensure that binocular vision will result. amblyopia and eccentric fixation If the vision in a strabismic (deviating or turning) eye is suppressed (turned off) for too long, that eye very well may develop “amblyopia” or a “lazy eye” condition. This means that the visual acuity in that eye no longer is as good as the visual acuity in the other eye, which is used all the time. In this case, when the normal eye is covered, thus forcing the strabismic eye to take over, the strabismic eye usually does not point exactly straight at the object being fixated. Therefore, the image of the object being viewed does not fall directly upon the macula, as it should. Rather, the image falls upon some eccentric point, away from 39 the macula, where the acuity is not as good. Thus, this is referred to as “eccentric fixation.” An eye is not a “lazy eye” simply because it turns and does not align with the other eye. Amblyopia (“lazy eye”) simply refers to decreased visual acuity in one eye, compared to the other eye. That is, an eye is referred to as “lazy” because it does not see as clearly as the other eye. The most common reason for amblyopia is the presence of eccentric fixation in a strabismic eye. acquired muscle palsy Damage to cranial nerve III, IV, or VI often will cause a “palsy” (paralysis or paresis) of the extraocular muscle(s) innervated by that nerve. The cause of the palsy usually is acquired (due to a lesion, a stroke, or other trauma), although occasionally it can be congenital (at birth). An extraocular palsy may cause the eyes to be misaligned, which is a strabismus. The most common symptom of a muscle palsy is diplopia (double vision)—that is, seeing two images either side-by-side, one on top of the other, or displaced diagonally. When the oculomotor nerve (cranial nerve III) is damaged, a palsy in the medial rectus, superior rectus, inferior rectus, and/or inferior oblique muscle(s) may occur. If all of these muscles are affected, the effected eye will be turned outward and downward (due to unopposed action of the lateral rectus and superior oblique muscles). The affected eye cannot turn inward past the midline, nor can it turn upward past the midline. In a complete cranial nerve III paralysis, the upper eyelid also will be nearly closed from a ptosis. The pupil might be dilated and unreactive as well. When the trochlear nerve (cranial nerve IV) is damaged, a palsy of the superior oblique muscle may occur. Typically, this will resut in an excyclotorsion (outward rotation), along with a lesser hypertropia and esotropia (upward and inward movement) of the affected eye. People with this condition will experience both a vertical and a torsional diplopia, and they will compensate for this by tilting the head toward the shoulder of the unaffected eye. When utilizing the Bielschowsky head-tilt test, the person is told to tilt his/her head toward the shoulder of the affected eye. An overaction of the inferior oblique, and an elevation of the affected eye (and marked diplopia), will result. When the abducens nerve (cranial nerve VI) is damaged, a palsy of the lateral rectus (LR) muscle may occur, resulting in an esotropia of the affected eye. That eye generally will not be able to look outward past the midline, and it will be somewhat turned inward when the other eye is fixating straight ahead. Diplopia will be observed by the person 40 when he/she gazes to the side with the palsied muscle, and the person will compensate for this by turning his/her face toward the side of the palsied eye. An extraocular muscle palsy may resolve on its own with time; however, this may not occur. If the palsy and resultant diplopia are permanent, a prismatic correction may be incorporated into spectacle lenses to merge the double images into a single image. Some people prefer simply to keep one eye patched to take away their double vision. In some cases, muscle surgery is another option. However, it should not be performed for at least six months after the onset of diplopia, since the effects of the palsy may resolve spontaneously over a few weeks or months. If a ptosis (drooping upper eyelid) is involved, such as in a cranial nerve III paralysis, probably the best option is surgical elevation of the eyelid. The Maddox Rod Test is a type of dissimilar image test for ocular alignment. This subjective test requires one Maddox rod to be placed in front of the patient’s eye. Bar or loose prisms can be used to quantitate a horizontal or vertical deviation. It is important to remember that this test will not differentiate between the presence of a phoria or ;tropia.only the cover-uncover test can determine if a phoria or tropia is present 1 The COMT Performance Areas lists the Maddox Rod Test as one of the potential skills a.candidate may be required to perform for the COMT Performance Test 2 When measuring a phoria using a Maddox rod and bar or loose prisms, the direction of 41.the red line viewed by the patient is perpendicular to the direction of the red cylinders If Maddox rod is held horizontally Æ a vertical line results (use this orientation to )measure for esophoria and exophoria OD OS If Maddox rod is held vertically Æ a horizontal line results (use this orientation to )measure for hypophoria and hyperphoria OD OS :Steps Patient wears best corrected Rx.1 Maddox rod is held in front of patient’s eye (select to measure the horizontal or.2 42 )vertical deviation first Transilluminator is focused on the midline of the patient’s face.3 Explain to patient: “You will see a red line and a white dot. Is the dot.4 ”?superimposed on the red line If the patent answers “Yes, the dot is superimposed on the line,” then no - )deviation is present (proceed in checking the other orientation If the patent answers “No, the dot is not superimposed on the line,” then a - deviation is present (proceed with identifying and quantifying the deviation by holding up loose prisms in the proper orientation until the dot is superimposed on )the line How do you determine which direction to hold your prisms to quantify the horizontal ).deviation? (Assume Maddox rod is placed over patient’s OD OD OS If your patient sees: ◦ = No deviation the white light superimposed on the red line 43 If your patient sees: ◦ = Exo deviation (use BI )the red line to the left, white light prism to quantify on right side If your patient sees: ◦ = Eso deviation (use BO )the red line to the right, white light prism to quantify to the left side ?How do you determine which direction to hold your prisms for vertical deviation ).Assume Maddox rod is placed over patient’s OD( OD OS 44 If your patient sees: ◦ = No deviation the white light superimposed on the red line If your patient sees: ◦ = Rh deviation (use BD OD red line is above the white light prism to quantify, may be )recorded as LH deviation If your patient sees: ◦ = RH deviation (use BU red line is below the white light prism to quantify( Once the deviation is identified, bar or loose prisms are held in front of the Maddox rod until the line is centered on the light. This prism power equals the amount of.phoria or deviation present. Results should be recorded with this prism diopter ∆,)amount and the ocular deviation identified. Example: 10 RH′ (by Maddox Rod Test a 10 prism diopter right hyperphoria is found when the subjective test is performed at near or 33 cm (the prime′ indicates the test is performed at near). The test can be performed at 6 m and at 33 cm. The patient’s visual acuity must be sufficient to see.the light with one eye and the line with the other eye to perform test This test also requires good patient cooperation for adequate results. 45 Clinically, this test is rarely performed and not the preferred method for quantifying ocular misalignment as some of the objective cover tests such as the prism alternate cover test. However, this test may be very helpful for quickly verifying prescribed.prism for glasses 46