Istinye University & Eye Anatomy

Istinye University Overview

• Istinye University was established in 2015 by the 21st Century Anatolian Foundation.
• It is a continuation of the 25-year knowledge and experience of the MLPCare Group, which combines three hospital brands under one roof: Liv Hospital, Medical Park, and VM Medical Park.
• The university aims to be among the leading universities in Turkey and the world.
• Istinye University provides students with a wide range of knowledge, technology, and art, fostering a learning and development environment based on universal standards in teaching, research, and community service.

Eye Anatomy and Physiology

• The external structures of the eye include eyelids, conjunctiva, lacrimal glands, and extraocular muscles.
• The eyeball is composed of three layers:
  • Outer Layer: Sclera (white part) and Cornea
  • Middle Layer: Lens, Iris, and Pupil
  • Inner Layer: Retina and Macula
• Six extraocular muscles control the movement of each eye in relation to three axes: horizontal, vertical, and oblique

Internal Structures and Functions

• Iris: Provides the color of the eye and has a small round opening called the pupil, which allows light to enter the eye.
• Pupil: Constricts via action of the iris sphincter muscle innervated by CN III and dilates via action of the iris dilator muscle innervated by CN V to control the amount of light entering the eye.

Eye Conditions

• Ptosis: Drooping upper eyelid may be caused by an interruption in sympathetic innervation to the eyelid, muscle weakness, or damage to the oculomotor nerve.
• Diplopia: Double vision.
• Conjunctivitis: Redness, swelling of conjunctiva; may be itchy.
• Cataract: Opacity within the crystalline lens leads to a decrease in vision; most cataracts are age-related

Signs and Symptoms of Cataracts

• Clouded, blurred, or dim vision
• Increasing difficulty with vision at night
• Sensitivity to light and glare
• Need for brighter light for reading and other activities
• Seeing "halos" around lights
• Frequent changes in eyeglass or contact lens prescription
• Fading or yellowing of colors
• Double vision in a single eye

Subjective Data – Patient Profile

• Age
• Medical history
• Chronic diseases
• Last eye exam
• Using glasses or lenses

Subjective Data – Eye History

• Decreased vision
• Blurred vision
• Spots flying before your eyes
• Trouble seeing at night
• Diplopia
• Eye pain
• Redness in the eyes
• Excessive watering of the eyes
• Eye discharge
• Dry eyes
• History of eye surgery
• Glaucoma
• Cataract

Health History - Visual System Questions

• Describe the change in your vision and how it affects your daily life.
• Do you wear protective eyewear (sunglasses)?
• Do you wear contact lenses?
• If you use eye drops, how do you instill them?
• Do you have any allergies that cause eye symptoms?
• Do you have a family history of cataracts?
• Are your activities limited in any way by your eye problem?
• Does your eye problem affect your ability to read?
• Do you have any eye pain?

Checklist and General Approach for Eye Examination

• Equipment: Penlight, gloves, Snellen chart, cotton
• Greet the patient and explain the examination techniques.
• Use a quiet, interruption-free room.
• Ensure sufficient light in the room for adequate observation.
• Place the patient in an upright sitting position.
• Visualize the underlying structures for adequate description of findings.
• Always compare right and left eyes.

Patient Assessment via Inspection

• Observe overall facial and ophthalmic appearance.
• Eyes should be symmetric and normally placed on the face.
• The eyeball should not have a bulging or sunken appearance.

Visual Acuity Assessment

• A simple, non-invasive procedure using a Snellen chart and an occluder to cover the patient's eyes.
• The numbers indicate the degree of visual acuity when the patient can read that line of letters at a distance of 20 feet (6 meters).

Distance Vision Testing

• Ask the patient to stand or sit facing the Snellen chart at 20 feet.
• Remove glasses if the patient normally wears them.
• Instruct the patient to cover one eye and read as many lines as possible, then repeat for the other eye.
• If the patient uses glasses, perform the same task while wearing them.
• 20/20 vision is considered normal acuity

Near Vision Testing

• Assess near vision using any printed material written at an appropriate reading level.

Vision Conditions

• Emmetropia: Normal vision
• Myopia (Nearsightedness): Objects near are clear, but objects farther away are blurry.
• Hyperopia (Farsightedness): Near vision impairment.
• Astigmatism: Non-uniform curvature of the cornea prevents parallel rays from being collected on the retina, requiring a cylindrical lens.

Visual Fields Testing

• The patient closes the right eye while the examiner closes their left eye, both fixating on the other's nose.
• The examiner holds up fists with the palms facing the examiner.
• The examiner then shows one or two fingers on each hand simultaneously and asks the patient how many fingers together they see.
• Hands are moved from the upper to the lower quadrants, repeating the examination.
• One hand should be in the nasal half, and the other in the temporal half of the visual fields.

Corneal Light Reflex

• Instruct the patient to look straight ahead.
• Focus a penlight on the corneas from 30 cm away at the midline.
• Observe the location of reflected light on the cornea.
• The reflected light should be seen symmetrically in the center of each cornea.
• Asymmetrical corneal light reflexes indicate an extraocular imbalance.
• Strabismus: Deviation of eye position in one or more directions.

Cardinal Fields of Gaze

• Assesses CNIII, CNIV, and CNVI cranial nerve functions
• Position the patient sitting and facing you.
• Ask the patient to follow an object (finger, pencil, or penlight) with their eyes.
• Move the object through the six fields of gaze in a smooth and steady manner, pausing at each extreme position to detect any nystagmus (involuntary movement), returning to the center after each field is tested.
• Both eyes should move smoothly and symmetrically in each of the six fields of gaze.
• Accommodation: Pupils constricting with near vision.

Examining the Conjunctiva

• Separate the lid margins with fingers.
• Have the patient look up, down, and to the right and left.
• Inspect the surface of the bulbar conjunctiva for color, redness, swelling, exudate, or foreign bodies.
• Gently pull the lower lid toward the cheek with your thumb and inspect the surface of the bulbar conjunctiva for color, inflammation, and edema.
• Normal Findings: Transparent with small blood vessels visible and appearing white except for a few small blood vessels.

Sclera and Cornea Examination

• Sclera: Examine the conjunctiva for color, lesion, and foreign bodies
  • Normal Findings: White with some small, superficial vessels and without exudate, lesion, or foreign bodies.
• Cornea: Assess with a penlight.
  • Stand in front of the patient.
  • Shine a penlight directly onto the cornea.
  • Move the light laterally and view the cornea from that angle, noting color, discharge, and lesion.
  • Normal Findings: Moist and shiny, with no discharge, cloudiness, opacities, or irregularities.

Pupil Assessment

• Stand in front of the patient in a darkened room.
• Note the shape of the pupils in millimeters.
• Move a penlight from the side to the front of one eye without allowing the light to shine on the other eye.
• Observe the pupillary reaction in that eye: This is the direct light reflex.

Consensual Light Reflex

• Observe the pupillary responses of both eyes, noticing briskness and equality of the reflex.
• A darkened room ensures the brisk response of pupils to light.
• A pupil that is illuminated constricts; the pupil in the other eye should constrict equally.
• Note the size of the pupil receiving light stimulus and the speed.

Pupillary Conditions

• Mydriasis: Pupil is larger than normal
• Miosis: Pupil is smaller than normal
• Anisocoria: Pupils are unequal (constricted)
• Photophobia: Sensitivity to lights
• Nystagmus: A vision condition in which the eyes make repetitive, uncontrolled movements, often resulting in reduced vision, depth perception, and can affect balance and coordination.