Disorders of the Special Senses (Eyes) PDF

Disorders of the Special Senses (Eyes) Unit 3 Human Pathophysiology Objectives At the end of the session students should be able to: Review the anatomy and physiology of the eyes Define selected conditions of the eyes Outline the risk factors of the selected c...

Disorders of the Special Senses (Eyes) Unit 3 Human Pathophysiology Objectives At the end of the session students should be able to: Review the anatomy and physiology of the eyes Define selected conditions of the eyes Outline the risk factors of the selected conditions Identify the causes of the selected conditions Discuss the pathophysiology of clinical features associated with the selected conditions Pathophysiology 2024 2 Objectives Outline investigative measures used in diagnosis of the selected conditions Describe the general management of the selected conditions Pharmacological Non-pharmacological Outline education and health promotion measures for prevention, risk reduction and preservation of function for the selected conditions Pathophysiology 2024 3 Selected Conditions – Disorders of the Eye 1. Trauma 2. Conjunctivitis 3. Keratitis 4. Cataract 5. Glaucoma 6. Retinopathies 7. Retinal detachment 8. Disorders of refraction Pathophysiology 2024 4 Anatomy and Physiology of the Eye Pathophysiology 2024 5  Anatomy and Physiology of the Eye Cornea has largest body of nerve bundle; extremely sensitive to pain Iris regulates the amount of light entering pupil Lens helps to focus image on retina Pathophysiology 2024 6  Anatomy of the Eye Wall composed of three layers (tunics) Sclera and cornea – outer fibrous layer Choroid – middle layer Retina – inner (sensory) layer Pathophysiology 2024 7  A&P of the Eye (Neurons of the Retina) Rods – most located towards edges of retina; allows dim light and peripheral vision Pathophysiology 2024 8  A&P of the Eye (Neurons of the Retina) Cones – three types (detect different colours) Colour blindness result if one type is missing Fovea centralis is area of retina with only cones No photoreceptor cells at optic disc / blind spot Pathophysiology 2024 9  Diagnostic Evaluations - Eye Visual field Determines function of optic pathways Assesses peripheral vision Visual acuity (Snellen Chart) Normal - 20/20 20/30—the person sees at 20 feet what a person with normal vision sees at 30 feet 20/70 is visual impairment 20/200 is legally blind Pathophysiology 2024 10 Diagnostic Evaluations - Eye Colour vision tests Determines individual’s ability to perceive primary colours and shades of colour Refraction Measurement of error of focus May be done subjectively (series of refractors-lenses; client chooses the clearest vision) or objectively (through retinoscopy or by automatic refraction) Pathophysiology 2024 11 Diagnostic Evaluations - Eye Ophthalmoscopy Ophthalmoscope used to visualize retina, optic disk, blood vessels Slit-Lamp Helps detect disorders of anterior chamber (equipment magnifies the anterior chamber, sclera and cornea) Tonometry Measures intraocular pressure (normal 12-21 mmHg) Pathophysiology 2024 12 Diagnostic Evaluations - Eye Fluorescein Angiography Provides information regarding vascular status of the eye and defects in retinal pigment permeability Eye and orbit sonography Sound waves used in diagnosis of intraocular and orbital lesions Electroretinography Electrode placed over eye to assess electrical response to light Used to evaluate disorders of the retina Pathophysiology 2024 13 Eye Trauma Pathophysiology 2024 14 Disorders of the Eye - Trauma Ocular (eye) trauma is injury to the eye resulting from blunt or penetrating injury, chemical exposure or blast Blunt force to eye causes compression and retraction of eye  bleeding Injury ranges from minor to severe Pathophysiology 2024 15  Disorders of the Eye - Trauma Types of injuries include: Laceration to eyelid caused by sharp object or fall Hyphaema bleeding in anterior chamber as a result of significant blunt force to eye Corneal abrasion caused by foreign body in eye Traumatic iritis often the result of blunt injury to eye Orbital fracture break in facial bone surrounding eye Globe rupture inside-out injury Pathophysiology 2024 16  Disorders of the Eye - Trauma Clinical Manifestations Pain Blurred vision Burning Diplopia (double vision) Subconjunctival haemorrhage Photosensitivity (sensitivity Lacrimation to light) Red conjunctiva Pupillary changes (size or Swollen lid shape) Pathophysiology 2024 17 Disorders of the Eye - Trauma Diagnostic Evaluation Slit light examination Visual acuity test X-ray or CT scan – rule out fracture of orbital bones Pathophysiology 2024 18 Disorders of the Eye - Trauma Management All eye trauma should be medically evaluated Irrigation first line of management for chemical injuries with isotonic saline or sterile water Patch / shield Suturing – eyelid laceration Pathophysiology 2024 19  Disorders of the Eye - Trauma Health Education / Promotion Avoid putting pressure on eye Do not attempt to touch, rub or Apply cold compress to remove foreign object in eye periorbital contusions Seek medical assistance Wear protective eyewear immediately (goggles) when doing activities Protective shield (resting on that may cause eye injury bony orbit) Pathophysiology 2024 20 Disorders of the Eye - Trauma Complications include: Corneal scarring Hyphaema – collection of blood in anterior chamber Pathophysiology 2024 21 Conjunctivitis Pathophysiology 2024 22  Disorder of the Eye - Conjunctivitis Inflammation of conjunctiva (aka Pink eye) Conjunctiva very sensitive to irritations and inflammation Results from bacterial or viral infection; allergens; chemical irritant; physical irritant, radiant energy Classified according to cause Risk factors include: exposure to allergen (allergic conjunctivitis), exposure to infested person (bacterial / viral conjunctivitis), use of contact lenses Pathophysiology 2024 23 Disorder of the Eye - Conjunctivitis Pathophysiology Pathophysiology 2024 24 Disorder of the Eye - Conjunctivitis Clinical Manifestations Severity varies depending on cause Foreign body sensation; Scratching or burning sensation; Itching Redness Photophobia Pathophysiology 2024 25 Disorder of the Eye - Conjunctivitis Clinical Manifestations Discharge (watery if viral, allergy or foreign body and mucopurulent if bacterial or fungal); Lacrimation Chemosis - (swelling of conjunctiva) – due to oozing of exudate from permeable capillaries Both eyes affected if caused by an infection Pathophysiology 2024 26 Disorder of the Eye - Conjunctivitis Diagnostic evaluation History Physical examination Eye swab for culture and sensitivity Pathophysiology 2024 27 Four types: Pathophysiology 2024 28 Disorder of the Eye – Allergic Conjunctivitis Usually characterized by itching Most common is seasonal allergic rhinoconjunctivitis (hay fever) IgE mediated hypersensitivity reaction precipitated by airborne allergens Bilateral tearing, itching, redness Pathophysiology 2024 29 Disorder of the Eye – Allergic Conjunctivitis Management Identify and avoid allergens Eye lavage with normal saline Cold compress Pharmacotherapy Topical mast cell stabilizers; histamine type 1 (H1) receptor antagonist; NSAIDs Systemic antihistamines – prolonged cases Topical steroids – short term course in severe cases Pathophysiology 2024 30  Disorder of the Eye – Bacterial Conjunctivitis Classified as: Acute - burning, mucopurulent or purulent discharge; eyelids sticky (gluing of lids). Self limited lasting 10-14/7 if untreated Hyperacute – severe sight-threatening; abrupt onset; copious yellow-green discharge; chemosis (swelling around cornea); swollen and tender eyelids; tender preauricular lymph nodes Chronic – often associated with blepharitis (inflammation of eyelid). Symptoms include itching, burning, foreign body sensation and crusting of eyelash on waking, loss of eyelash, recurrent styes and chalazia Pathophysiology 2024 31 Disorder of the Eye – Bacterial Conjunctivitis Management Eye lavage with normal saline Warm soaks – for crusting Pharmacotherapy Topical antibiotics Systemic antibiotics Topical steroids – short term course in severe cases Pathophysiology 2024 32  Disorder of the Eye – Viral Conjunctivitis Spread through direct or indirect contact with infected secretion Adenovirus type 3 one of the most common viruses implicated Clinical features: copious tearing, minimal exudate (watery discharge); usually associated with pharyngitis, fever and malaise Pathophysiology 2024 33  Disorder of the Eye – Chlamydial Conjunctivitis Transmitted by Chlamydia trachomatis via contaminated genital secretions Newborns can be infected during delivery Can also be transmitted through inadequately chlorinated swimming pools Treated with antibiotics Pathophysiology 2024 34 Disorders of the Eye - Conjunctivitis Treatment Normal saline to wash eyes Pharmacotherapy Antibiotic eyedrop if bacterial origin Antihistamine if allergy related Analgesic for pain Prevention and control measures Measures to prevent spread e.g., careful handwashing Pathophysiology 2024 35 Keratitis Pathophysiology 2024 36  Disorder of the Eye - Keratitis Inflammation of cornea May result from trauma, infections, misuse of contact lenses, hypersensitivity reactions, ischaemia (diminished blood supply to an organ or tissue decreased oxygen for cellular metabolism) Infectious agents include bacteria, virus, protozoans, fungi Pathophysiology 2024 37  SLE – Systemic Lupus Erythematosus NSAIDs – Nonsteroidal anti-inflammatory drugs Disorder of the Eye - Keratitis HSV – Herpes simplex virus Two types: Non-ulcerative and Ulcerative Non-ulcerative Keratitis Ulcerative Keratitis Stroma of cornea is affected by Destruction of portions of epithelium inflammatory process only. Overlying and underlying stroma of cornea epithelium is intact Causes include: pathogens e.g. HSV; chemical agents; persistent corneal Associated with many diseases e.g. exposure; loss of corneal sensation SLE, Syphilis e.g. from trigeminal nerve paralysis; vitamin A deficiency Treatment: topical antibiotics and NSAIDs Pathophysiology 2024 38  Disorder of the Eye - Keratitis Clinical features vary. May include: Photophobia – sensitivity to light Pain and (or) foreign body sensation Excessive lacrimation (tearing) Redness Decreased vision Blepharospasm – abnormal involuntary blinking or spasm of the eyelids (rare) Pathophysiology 2024 39 Disorder of the Eye - Keratitis Diagnosis Fluorescein staining and examination with Slit-Lamp Identify abrasion or ulceration Management Depends on cause and degree of injury Antibiotic (e.g. Augmentin) or antiviral (e.g. acyclovir) ointment (ung) Atropine (mydriatic) eyedrop – prevents adhesion between iris and lens Eye patch x 24 hours for ulcerative keratitis Surgical intervention – conjunctival excision, keratoplasty Pathophysiology 2024 40 Disorder of the Eye - Keratitis Health Promotion / Education How to use medication Avoid rubbing eye Hand hygiene Proper wearing of contact lenses Wearing protective equipment when at risk for traumatic eye injuries Pathophysiology 2024 41 Cataract Pathophysiology 2024 42  Disorder of the Eye - Cataract Opacity of the eye’s normally clear, transparent crystalline lens or its capsule Interferes with transmission of light to the retina and the ability to see images clearly Vision impairment depends on the size, density, and location in the lens Leading cause of blindness globally (WHO, 2017) Pathophysiology 2024 43  Disorder of the Eye - Cataract Normal lens comprised of semi-solid, clear gelatinous protein enveloped in a capsule Lens have significant refractive ability Chemical changes in the lens protein may cause coagulation  opacity Light passing through lens to retina is scattered or blocked  blurred / distorted vision Pathophysiology 2024 44  Disorder of the Eye - Cataract Multifactorial. Pathogenesis not clearly understood. May be congenital or acquired Aging (due to degenerative changes) Risk Systemic diseases e.g. Diabetes mellitus Factors Eye trauma (penetrating or blunt injuries; foreign bodies) Other eye disorders e.g. uveitis (inflammation of uveal tract) Genetic association Pathophysiology 2024 45  Disorder of the Eye - Cataract Risk Factors Lifestyle factors e.g. cigarette smoking Environmental factors e.g. exposure to ionizing radiation, bright sunlight Long term use of certain drugs e.g. corticosteroids Hair or eyelash dye containing aniline Pathophysiology 2024 46  Disorder of the Eye - Cataract Clinical Manifestations Dimmed or blurred vision; Glare from bright lights; Poor night vision; Gradual painless loss of vision Pupil grey or milky white; absence of red reflex As cataract worsens, stronger glasses no longer improve vision Usually bilateral (unless related to trauma or congenital) Vision affected by cataract Pathophysiology 2024 47  Disorder of the Eye - Cataract Diagnostic Evaluation History Physical assessment Snellen visual acuity test Ophthalmoscopic examination Slit Lamp examination A-scan ultrasonography Pathophysiology 2024 48  Disorder of the Eye - Cataract Management No effective medical treatment Glasses may improve vision for a while Mydriatics (drugs used to dilate pupil) may help vision for a while Surgery is the only treatment for correcting the condition Intracapsular or extracapsular extraction Intraocular lens (IOL) implanted at time of surgery Pathophysiology 2024 49  Disorder of the Eye - Cataract Health Promotion / Education Wear sunglasses when exposed to ultraviolet (UV) rays Avoid cigarette smoking Control body weight Avoid eye trauma Pre and post-operative instructions Pathophysiology 2024 50 Glaucoma Pathophysiology 2024 51  Disorder of the Eye - Glaucoma Eye condition in which there is damage to optic nerve (optic neuropathy) and gradual loss of peripheral vision resulting from increased pressure in the eye Imbalance between production of aqueous humor and its drainage resulting in visual impairment Pathophysiology 2024 52 Disorders of the Eye - Glaucoma Incidence increases in persons > 40 years old; family history; more prevalent in African Americans Two types: closed-angle (acute) and open-angle (chronic) Primary open angle glaucoma is the most common form Pathophysiology 2024 53  Disorder of the Eye - Glaucoma Angle - area between iris and cornea through which aqueous humor must flow to escape via the trabecular network Pathophysiology 2024 54  Disorder of the Eye - Glaucoma Pathophysiology Aqueous humor (produced by ciliary processes into anterior chamber) normally flows out of eye through a mesh-like channel (trabecular meshwork) at the outer angle of the anterior chamber (junction of cornea and iris) into canal of Schlemm  general circulation Pathophysiology 2024 55  Disorder of the Eye - Glaucoma Pathophysiology If channel becomes blocked, fluid builds up  increased intraocular pressure and damage to optic nerve Pathophysiology 2024 56  Disorder of the Eye - Glaucoma Risk Factors Pathophysiology 2024 57  Disorder of the Eye - Glaucoma Complete eye Tonometry (measures pressure within eyes) examination: Diagnostic Slit lamp examination Visual acuity Evaluation Gonioscopy (special Visual field lens used to examine measurement eye) Fundoscopy Optic nerve imaging Pathophysiology 2024 58  Disorder of the Eye – Glaucoma (Open angle / Chronic) Cause unknown. Runs in families Gradual blockage of scleral venous passage. Aqueous humor reabsorbed at slower rate  of fluid and increase IOP Angle wide and open Insidious; painless; halos; increased cup- to-disc ratio IOP – intraocular pressure Pathophysiology 2024 59  Disorder of the Eye - Glaucoma Open angle (Chronic) - Management Pharmacotherapy Surgery (if drugs fail) Beta adrenergic antagonist Corneoscleral trephine Prostaglandin analogs Iridencleisis (obsolete surgery) Adrenergic agonists Sclerectomy Carbonic anhydrase inhibitors Cyclocryotherapy Cholinergic agonists Trabeculoplasty Pathophysiology 2024 60  Drugs Beta adrenergic Adrenergics Prostaglandin analogs Carbonic Carbonic blocking agents (Mydriatics) anhydrase anhydrase inhibitors inhibitors ↓ production of ↓ production of ↑aqueous outflow ↓ production of Systemic agent aqueous humor aqueous humor aqueous humor and ↑ its May cause E.g. Can produce absorption conjunctival E.g. acetazoamide systemic effects hyperemia and Dorzolamide (Diamox) such as E.g. Brimonidine permanent (Trusopt) bronchospasm, (Alphagan) changes in colour bradycardia and of iris and cardiac failure eyebrows E.g. Timolol E.g. Latanoprost (Timoptic) (Xalantan) - drug of choice for chronic 61 glaucoma  Disorder of the Eye – Glaucoma (Closed angle / Acute) Drainage canal blocked by sudden increase in intraocular pressure (>30 mmHg) Angle between iris and cornea closed or narrowed Excruciating pain; rapid visual loss; red eye; nausea and vomiting; halos; fixed mid-dilated pupil. Medical emergency Pathophysiology 2024 62  Disorder of the Eye – Glaucoma (Closed angle / Acute) Closed angle (Acute) - Management Pharmacotherapy initiated to control eye pressure before surgery Surgery (when IOP is reduced) – Iridectomy – Iridencleisis – Trabeculectomy – Thermosclerectomy IOP – intraocular pressure Pathophysiology 2024 63  Disorder of the Eye - Glaucoma Health Promotion / Education Encourage person > 40 years old with family history of glaucoma to get complete eye examination done every 1-2 years Persons with conditions such as Diabetes mellitus and Hypertension to have annual eye examination done Avoid caffeine, stressful activities e.g. heavy lifting), emotional upsets and constrictive clothing as these can increase IOP in persons with glaucoma Pathophysiology 2024 64  Disorder of the Eye - Glaucoma Health Promotion / Education Medication and follow-up appointment compliance Glaucoma cannot be cured but can be controlled Medic alert identification Avoid constipation Moderate use of eyes Pathophysiology 2024 65 Retinopathies Pathophysiology 2024 66  Disorder of the Eye - Retinopathies Disorders of retinal vessels resulting in microaneurysms, neovascularization, haemorrhage and formation of retinal opacities Microaneurysm – outpouchings of retinal blood vessels. Leaks plasma resulting in oedema which cause retina to appear hazy Neovascularization – formation of new blood vessels which are fragile, leak protein and likely to bleed Pathophysiology 2024 67  Disorder of the Eye - Retinopathies Haemorrhage – may be pre-retinal, intra- retinal or sub-retinal. Photocoagulation can be used to treat haemorrhage as well as neovascularization Opacities – caused by haemorrhage, exudate, oedema, tissue proliferation and cotton-wool spots Pathophysiology 2024 68  Disorder of the Eye - Retinopathies Diabetic Retinopathy Cause not clear. Two types: non-proliferative (confined to retina) and proliferative (neovascularization occurring in front of retina). Third leading cause of blindness Photocoagulation is the major direct treatment modality Pathophysiology 2024 69  Disorder of the Eye - Retinopathies Hypertensive Retinopathy Persistently elevated blood pressure (BP) causes hypertrophy of arteriolar walls  reduction of capillary perfusion pressure Disruption of blood-retinal barrier, necrosis of smooth muscle and endothelial cells, exudation of blood and lipids and retinal ischaemia occur Advanced signs of hypertensive retinopathy is a predictor of stroke Condition regress when blood pressure is controlled Pathophysiology 2024 70  Disorder of the Eye - Retinopathies Health Promotion / Education Measures to control underlying condition Regular eye examination Pathophysiology 2024 71  Retinal Detachment Pathophysiology 2024 72 Disorder of the Eye – Retinal Detachment Retina peels away from underlying layer of support tissue Starts as partial detachment, progress rapidly to total detachment not managed with urgency Leads to vision loss / blindness Pathophysiology 2024 73 Disorders of the Eye – Retinal Detachment Pathophysiology 2024 74  Disorder of the Eye – Retinal Detachment Risk Factors Age Myopia (near-sightedness) Family history of retinal detachment, congenital eye disease e.g. glaucoma Hereditary vitreopathies Pathophysiology 2024 75  Disorder of the Eye – Retinal Detachment Clinical Manifestations Painless changes in vision Occur as vitreous pulls away from Flashing lights posterior section of eye Small floaters or spots in field of vision Shadow or dark curtain progressing across visual field (as condition progresses) Pathophysiology 2024 76  Disorder of the Eye – Retinal Detachment Diagnostic Evaluation History Physical examination Indirect ophthalmoscopy – detects altered red reflex; shows grey or opaque retina (normally transparent) Slit-Lamp examination Gonioscopy Pathophysiology 2024 77  Disorder of the Eye – Retinal Detachment Management Sedation Bed rest Eye patch – restrict eye movement Pathophysiology 2024 78  Disorder of the Eye – Retinal Detachment Management Surgery Photocoagulation – produce exudate between pigment epithelium and retina Electrodiathermy – drains sub-retinal fluid Laser or Cryosurgery – seal retinal tear Scleral buckling – primary surgical procedure, performed to reattach retina Pathophysiology 2024 79  Disorder of the Eye – Retinal Detachment Health Education / Promotion Post op: Warm compress for about 10 minutes regularly throughout day Avoid straining or bending Avoid rapid eye movement Administration of eyedrop Follow-up appointments Pathophysiology 2024 80 Refraction Disorders Pathophysiology 2024 81  Disorder of the Eye – Refraction Disorders Refraction: the bending of light waves enter the eye to form an image on the retina Light passing through a convex lens causes light rays to converge Convex surfaces of cornea and lens refract light entering eye with converging on retina Pathophysiology 2024 82  Disorder of the Eye – Refraction Disorders Accommodation: the ability of the eye to change its focus from distant objects to near objects Eyes are set for distant vision (> 20 feet away) Light waves of images < 20 feet away from the eyes are diverged and would come into focus behind the retina Lens must change shape to focus for closer images (thickens to enable stronger converging of light waves so that close images are focused on retina) Pathophysiology 2024 83  Disorder of the Eye – Refraction Disorders Four main disorders of refraction: myopia, hyperopia, presbyopia and astigmatism Myopia (nearsighted) – Eyeball too long. Image falls in front of retina. Distant objects blurred. Corrected with concave lenses Hyperopia (farsighted) – AP diameter of eyeball is too short. Image falls behind retina. Near images are blurred. Corrected with convex lenses Pathophysiology 2024 84  Disorder of the Eye – Refraction Disorders Presbyopia – rigidity of lens with decrease accommodation due to ageing Genetic factor S/S: needing brighter light to read, holds reading material at arms length, difficulty reading small print, eye strain or headache from reading S/S – signs and symptoms Pathophysiology 2024 85  Disorder of the Eye – Refraction Disorders Astigmatism – unequal curvature of cornea (egg shaped) and sometimes in curvature of lens. Some portion of image is focused on retina while other portions are blurred causing distorted vision Ciliary muscle fatigue and headache results as eye attempts to accommodate S/S: blurred vision, squinting, rubbing of eyes, headache Management: artificial lens Pathophysiology 2024 86 Disorders of refraction Pathophysiology 2024 87 Disorders of refraction Pathophysiology 2024 88  Disorder of the Eye – Refraction Disorders Health Education / Promotion For class discussion / assignment Pathophysiology 2024 89 References Eckman, M. & Share, D. (2013). Pathophysiology made incredibly easy. Philadelphia: Lippincott, Williams & Wilkins Grossman, S. & Porth, C. (2014). Porth’s pathophysiology concepts of altered health states. Philadelphia: Lippincott, Williams & Wilkins Hole, J. (1993). Human anatomy and physiology. Iowa: Wm. C. Brown Publishers Nettina, S. (2014). Lippincott manual of nursing practice. Philadelphia: Lippincott, Williams & Wilkins Pathophysiology 2024 90