Ocular Diseases PDF

Animal Diseases -- Lecture 12 **Anatomy Review** Fibrous Layer -- sclera & cornea Vascular Layer -- Choroid, Ciliary body & iris Nerve Layer -- Retina Tapedum Lucidum -- highly reflective area of the retina that allows for night vision Commonly, animals are seen for disease of accessory struct...

Animal Diseases -- Lecture 12 **Anatomy Review** Fibrous Layer -- sclera & cornea Vascular Layer -- Choroid, Ciliary body & iris Nerve Layer -- Retina Tapedum Lucidum -- highly reflective area of the retina that allows for night vision Commonly, animals are seen for disease of accessory structures - Eyelids - Conjunctiva - Tear ducts - Third eyelid -- nictitating membrane - Lacrimal glands **Overview & Terms** Ocular diseases & disorders are common in vet med Efficient triage, & diagnosis may avoid sight loss in many cases - Miosis (pupil constriction) vs Mydriasis (Pupil Dilation) - Blepharospasm -- uncontrolled blinking, trouble opening eye - Blepharitis -- inflammation around eyelid - Chemosis -- swollen conjunctiva - Hyperemia -- bloodshot eyes - Epiphora -- watery eyes - Keratitis -- inflammation of the cornea - Photophobia -- light sensitivity - Scleritis -- inflammation of the sclera **Conjunctivitis** Inflammation of the conjunctivas - Often secondary to other diseases Infectious or environmental   - Highly vascular Infectious (often cats) - Herpes, calicivirus, chlamydia Non-Infectious (often Dogs) - Bacterial   - Immune mediated - Allergies - Ectropion/Entropion - Injury or FB - Decreased tear production Clinical Signs Treatment - Chemosis - Ocular antibiotics, ointments if bacterial - Hyperemia - Nursing care to keep eyes clean - Ocular discharge - Discomfort, squinting - Upper resp in cats **Epiphora "Watery Eyes"** - Overproduction of tears from pain or irritation Clinical Signs - Lashes can rub against cornea - "watery" eyes / wet facial hair Causes - Discoloration of facial hair - Faulty drainage of lacrimal ducts - Dacryocystitis (inflammation of the lacrimal sac) Treatment - Absence of lacrimal ducts - Treat underlying cause Poodles, cocker spaniels - Flush lacrimal ducts (unblock) Brachycephalics - Surgery - Large globes, small orbits = problems - Little room for tears so they spill out - Lashes & folds rub eye globe, causing irritation - Anatomy entraps tears and moisture = itchy - Ichy face causes inflammation causes plugged lacrimal gland - Chronic, budget accordingly **Entropion** Eyelids roll inward against cornea - Think ENT (Enters eye) - Lids don't perform their intended duty to protect eye   - Common in dogs Clinical Signs - Pain - Chemosis - Blepharospasm - Epiphora - Conjunctivitis and conjunctival erythema - Ulcerative keratitis Causes: Congenital -- large orbit with deep set eyes (poodles, collies, Danes, retrievers, setters, Dobermans, shar pei) Acquired, nonspecific -- surgery or trauma Acquired spastic -- secondary to painful corneal lesions, conjunctivitis (often cats) **Ectropion** Eyelids roll outwards exposing cornea - Lids excessively droopy - Natural characteristic in Bassets, bloodhounds, cocker spaniels, bulldogs, saint Bernards etc - Can also be secondary to muscular diseases - Can develop more severe clinical symptoms such as conjunctivitis epiphora, keratitis (from exposure) **Hypertrophy of Nictitating Gland**   "Cherry Eye" - Red enlarged nictitating membrane - Usually not painful but irritating - Bassets, beagles, Boston's, cockers, bulldogs - Should always rule out tumors - Can cause epiphora Surgery is Curative for Cherry eye, Ectropion & Entropion   **Glaucoma** - Related to decreased outflow of aqueous humor - Glaucoma is a group of diseases characterized by increased intraoral pressure (IOP) with resultant retinal & optic disc destruction [Primary Glaucoma ] - Inherited (poor aqueous drainage) - Cockers, bassets, chow chow [Secondary Glaucoma ] - Obstruction of drainage angles - Neoplasia, uveitis, lens luxation, hemorrhage [Early Clinical Signs ] - Sluggish, slightly dilated pupils, mild bulbar conjunctival venous congestion, & early enlargement of the eye - Seen as disease starts [Chronic Clinical Signs ] - Globes have luxated & cataractous lenses - [Acute ] - Pain, hyperemia, dilated pupil +/- blindness - IOP often severely elevated \>60mmHg - Blindness within hours due to disruption of retinal ganglion cells - Will become permanent if IOP is not lowered - Referral for surgery Chronic - Pain, enlarged globe, optic disk cupping, blindness - Sustained IOP over an extended period - Pets unresponsive to medical treatment - Enucleation often recommended [Client Education ] - May be emergent - Lifelong treatment, monitoring - Very painful & progressive - Enucleation will greatly improve quality of life - Blind dogs & cats do well **Ulcerative Keratitis** AKA Corneal Ulcer - Cornea is composed of five layers 1. Epithelium 2. Bowman's 3. Stroma 4. Descemet Membrane 5. Endothelium Full thickened loss of corneal epithelium that exposes underlying stroma Often caused by: - Trauma - Chemical - Foreign object - KCS (dry eye) - Herpes virus in cats Patient usually present with pain, epiphora, blepharospasms, conjunctival hyperemia - Uncomplicated ulcers will heal in under 7 days in normal healthy animals - Must treat underlying condition - May be chronic, due to other conditions such as entropion - Treatment should always include a thorough exam under the eyelid **Keratoconjunctivitis Sicca** "dry eye" or "KCS" - Eyes need a continuous production & distribution of tear to maintain a healthy eye - Tears clean, lubricate, nourish, reduce bacteria & aid in healing - Dogs and cats have wo lacrimal glands Lateral superior orbit (70% of tears) Base of third eyelid (30% of tears) - Loss of both glands results in KCS Guarded Prognosis - Failure to treat will lead to blindness - Must stimulate tears with topical cyclosporine - Must support disease with topical artificial tears - Meds are required frequently, often forever **Cataracts** - Most common disease involving the lens, especially in dogs - Opaque cloudy cornea 'will cause a progressive loss of vision - Inherited disorder - Or secondary to diabetes mellitus, hypocalcemia, trauma, nutritional deficiencies, electric shock, uveitis, lens luxation - Surgical removal of cataract is necessary -- referral - Will treat one eye at a time - Must treat underlying condition if possible **Anterior Uveitis** - Inflammation of uvea = uveitis - Uvea includes iris, ciliary body, & choroid - Must treat properly to avoid blindness - Causes include Trauma, infection from surrounding areas, neoplasia, viral diseases, parasites, immune mediated & more Clinical Signs - Pain - Prolapsed third eyelid - Vision defects - Chemosis - Scleral injection   Treatment - Treat underlying condition of possible - Control inflammation with topical +/- oral anti-inflammatories and/or steroids - Topical atropine helps to restore vascular permeability and prevent adhesion of the lens Uncomplicated cases do well with treatment **Progressive Retinal Atrophy** - Term used to describe a group of hereditary retinal disorders seen in many breeds of dogs - Sometimes cats due to a taurine deficiency - Patients suffer from retinal thinning, retinal nerve atrophy, vascular narrowing - Detected in dogs as young as six months - Slow progression towards blindness - Loss of night vision, loss of low-light vision, eventually day vision No treatments available Common in toy breeds, poodles, retreivers, setters, schnauzers, cockers, collies. Educate clients **Horner Syndrome** Seen more in cats than dogs Clinical Signs: - Droopy upper lids (ptosis), unilateral miosis with possible enothahalmos (sunken eye) and 3^rd^ eyelid prolapse Treat underlying condition or may be self-resolving, protect eye with lubricants from ulcers