common eye issues and tx SA

Conjunctivitis

·    Clinical signs:

o  Acute

§ Hyperaemia (increased blood flow)

§ Chemosis/oedema, swelling/thickening

§ Discharge – watery, mucoid, mucopurulent

§ Mild irritation

§ Can be unilateral or bilateral

o  Chronic

§ Thickening of epithelium

§ Hyperpigmentation

§ Follicular hyperplasia

·    Causes:

o  Dogs

§ Primary infectious: viral (CHV), bacterial, parasitic (leishmaniasis)

§ Secondary bacterial (most common): staphylococcus, streptococcus (gram +ve, commensals)

§ Non-infectious: FBs, irritants, allergies, entropion, ectropion, eyelid margins, KCS

o  Cats

§ Primary infectious (most common): Chlamydia felis, Mycoplasma felis, viral (FHV, FCV)

·    Chlamydia felis – unilateral progressing to bilateral, hyperaemia, mild URT disease

·    FHV – URT signs, bilateral conjunctivitis and ulceration

§ Secondary bacterial infection

·    Investigations:

o  Conjunctival swab and PCR for Chlamydia felis, FHV

·    Treatment:

o  Treat/remove underlying cause, e.g. remove FB

o  Topical antibiotic therapy – fusidic acid is first choice (licensed, gram +ve organisms)

o  If due to Chlamydia felis – topical chlortetracycline, systemic doxycyline

o  If due to FHV – topical ganciclovir, fusidic acid for eyes (+ amoxiclav if respiratory signs), nursing care

Uveitis 

·    Pathophysiology: increased blood supply, increased vessel permeability, WBC migration

·    Clinical signs:

o  Pain – blepharospasm, increased lacrimation, photophobia

o  Red eye – episcleral and conjunctival hyperaemia

o  Miois, swollen/dull iris

o  Inflammation in anterior chamber – aqueous flare, hypopyon, hyphaemia, keratic precipitates

o  Corneal oedema

o  Low IOP

·    Diagnosis: clinical + ophthalmic exam, blood profile, infectious disease profile, radiography, U/S, cytology, histopathology – to find underlying cause

·    Treatment:

o  Treat underlying cause

o  Topical +/- systemic anti-inflammatories

o  Topical atropine to effect

·    Causes:

o  Local

§ Trauma, e.g. corneal ulcer

§ Immune mediated

§ Neoplasia, e.g. FDIM

o  Systemic

§ Infection, e.g. FIV/FIP/FeLV

§ Metabolic, e.g. hyperlipidaemia

§ Neoplasia, e.g. lymphoma

o  Toxoplasma gondii induced

§ Treatment: clindamycin

Glaucoma

·    Clinical signs:

o  Acute

§ Pain – blepharospasm, increased lacrimation, photophobia

§ Vision loss

§ Corneal oedema

§ Episcleral vessel congestion

§ Fixed, dilated pupil, no PLR

·    Causes:

o  Hereditary primary glaucoma – spaniels, retriever, huskies

o  Secondary glaucoma, to uveitis, lens luxation, etc.

·    Diagnosis: tonometry to measure IOP, (normal 10-25), acute glaucoma > 40mmHg

o  Topical LA – troparacaine

·    Treatment:

o  Reduce IOP – depending on cause

§ Primary cause – prostaglandin analogue, or treat underlying cause

o  Analgesia

o  Refer

·    Consequences of chronic glaucoma: globe enlargement, corneal changes, lens luxation, cataracts

Dry eye (KCS)

Canine keratoconjunctivitis

·    Clinical signs:

o  Acute

§ Recurrent conjunctivitis

§ Sticky discharge – sticks to ocular surface

§ Blepharospasm

o  Chronic

§ Corneal vascularisation, fibrosis and pigmentation

§ Reduced vision

·    Causes:

o  Immune mediated (most common)

o  Congenital, e.g. lacrimal gland hypoplasia

o  Neurogenic, e.g. unilateral, dry eye/nose

o  Toxic

o  Endocrine disease, e.g. DM, hypoT4

o  Iatrogenic, e.g. removal of third eyelid

·    Diagnosis:

o  STT <10mm/min

·    Treatment: ciclosporin, tear substitutes, fusidic acid if secondary infection

·    Neurogenic KCS – when parasympathetic nerve is affected (unilateral)

o  See dry ipsilateral nostril, otitis media

Corneal ulcers

·    Clinical signs:

o  Pain – blepharospasm, lacrimation, photophobia

o  Conjunctival hyperaemia

o  Ocular discharge

o  Corneal oedema

o  Reflex uveitis

·    Causes:

o  Trauma, e.g. FB, abrasions, lacerations, chemical injuries

o  Tear film production – lack of tears (KCS)

o  Adnexal conditions, e.g. entropion, eyelid mass, eyelash problems

o  Primary corneal disease, e.g. brachycephalic conformation, SCCEDs

o  Infection – bacterial keratitis, FHV

o  Neurological disease

·    Diagnosis:

o  Signs of pain – blepharospasm, lacrimation, photophobia

o  Reflexes

o  Thorough CE, look under third eyelid for FB

o  STT may be above normal (falsely elevated by tear production)

o  Fluorescin staining

o  Corneal cytology +/- C+S if suscpect infection

·    Types of ulcers

o  Superficial corneal – epithelial loss only, picks up stain

o  Stromal – loss of epithelium + storma, see visible crater, picks up stain

o  Descemetocoele – complete stromal loss, walls pick up stain but descemets membrane doesn’t (ring-appearance)

o  Keratomalacia/melting corneal ulcers – gloopy

·    Treatment

o  Superficial/stomal

§ Identify and treat underlying cause

§ Chloramphenicol to prevent/treat secondary infection

§ NSAIDs for analgesia

§ If reflex uveitis – 1 drop atropine

o  Deep

§ Medical therapy

§ If not working – grafting surgery to prevent perforation

o  Infected/melted: gentamicin

Keratomalacia/ melting corneal ulcers

·    Clinical signs:

o  Very painful

o  Gloopy/gelatinous discharge

o  Ill-defined, soft edges (melting butter)

o  Marked corneal oedema and anteriour uveitis

o  Can perforate within hours

·    Occur when enzymes break down and digest corneal stroma

·    Diagnosis:

o  Corneal cytology, corneal swab for C+S

·    Treatment

o  Treat secondary infection, based on C+S (often topical fluroquinalones, gentamicin)

o  NSAIDs +/- opioids for analgesia

o  Atropine if reflex uveitis

o  Close monitoring

SCCED

Spontaneous chronic corneal epithelial defect

·    Start off as superficial corneal ulcer, loose lip of epithelium cannot adhere to stroma

·    Diagnosis:

o  Stains with dye, not adherent to epithelium

·    Treatment:

o  Disrupt epithelial membrane to allow attachment

§ Debridement – sterile cotton bud, topical LA

§ Debridement + keratotomy/keratectomy – cotton bud, then grid pattern with needle or diamond bur (NOT IN CATS)

o  Prevent/treat secondary infections – chloramphenicol

o  NSAIDs for analgesia

o  If reflex uveitis – atropine

Lens luxation

·    Anterior > posterior

·    Clinical signs:

o  Acutely painful eye

o  Signs of glaucoma – episcleral vessel congestions, raised IOP, diffuse oedema, vision loss

o  Lens outline visible – take photo with flash

·    Treatment:

o  Refer for surgical removal or lens push back – live latanoprost to constrict pupil and keep lens in place

o  NSAIDs +/- opioid

Horner’s syndrome

·    Clinical signs:

o  Miosis

o  Third eyelid protrusion

o  Ptosis

o  Enophthalmos

·    Diagnosis:

o  Phenylephrine test – 1 drop in both eyes, if 3^rd order pupil will dilate <20m, if 1^st/2^nd order will take >20min or not at all

Neoplasia’s

·    Eyelid masses – usually benign

·    Uveal neoplasia’s

o  Feline diffuse iris melanoma – most common in cays

§ See hyperpigmented iris spots, abnormalities in pupil shape, uveitis, glaucoma, unilateral

§ Diagnosis: clinical signs, histopathology post-enucleation

§ Treatment: enucleation

·    Indications for enucleation: rapid growth, cells in anterior chamber, secondary glaucoma, infiltrating drainage angle

o  Iris melanoma – most common in dogs

§ See discrete focal pigmented masses

§ Monitor, enucleation if painful or worried

§ U/S to differentiate from cyst

Eosinophilic keratitis

·    Clinical signs: white/pale pink spots on cornea (cottage cheese)

·    Causes; immune mediated

·    Diagnosis: clinical signs, cytology (mixed cellular infiltrate)

·    Treatment: topical corticosteroid or ciclosporin

Pannus

·    Chronic superficial keratitis

·    Clinical signs:

o  Cellular infiltrate into cornea, vascularisation

o  Non-painful

·    Diagnosis: clinical appearance +/- cytology (lymphoplasmacytic inflammation)

·    Treatment: topical steroid +/- ciclosporin

Globe prolapse

·    EMERGENCY

·    Consequences:

o  Traction on optic nerve ® permanent blindness

o  Displaced in front of eyelids preventing blink ® dries ocular surface ® risk of corneal ulceration

o  Rupture of extraocular muscles

·    Prognosis:

o  Better in brachycephalic as shallow orbit

o  Better if eye is moving, positive PLR

o  Worse in cats as deep orbits so harder to replace, requires more force to prolapse so usually very badly injured

o  Worse if corneal/scleral rupture also

·    Treatment – immediate tx required as EMERGENCY SITUATION

o  Keep globe moist using lubricating ointment

o  Analgesia, sedation – prevent self-trauma

o  GA for globe replacement – lateral canthotomy (make eyelid opening larger), pull eyelids out and over, suture lateral canthotomy, temporal tarsorraphy (suture eyelids together to prevent immediate re-prolapse – not full thickness)

o  After care – systemic + topical antibiotics (chloramphenicol), NSAIDs, buster collar

Cataract

·    Differentiate from nuclear sclerosis with distant direct ophthalmoscopy – look for tapetal reflex

o  Cataract – still cloudy, cannot see through pupil

o  Nuclear sclerosis – can see tapetal reflex

·    Causes:

o  Age-related change

o  Secondary to DM – glucose diffuses into lens, not metabolised into lactate, unable to diffuse out, water drawn into lens, causing opacity

·    Types

o  Incipient – very small

o  Immature – doesn’t fill whole lens

o  Mature – fills whole lens

o  Hyper-mature – fills entire lens, so firms starts to wrinkle, see edges of lens