SA Ophthalmology

Ophthalmoscope setting for looking at retina, lens and cornea

Retina = -3 - +3
Lens = +8 - +12
Cornea = +20

What is measured by the schrimer tear test

Aqueous portion of tear

Normal result of scrimer tear test

15-25mm in 60s

What is used to measure the intraocular pressure

Tonometry

Normal intraocular pressure

10-25mmHg

If you have multiple intraocular pressure readings which one should you use

Lowest

When should U/S of the eye not be done

If there is a risk of globe rupture (e.g. deep ulcer)

Distichiasis

Hairs growing in an abnormal location on the eyelid margin

Treatment of distchiasis

Sedate and pluck (will regrow)

Electrolysis

Cryotherapy

Eyelid split surgery

Ectopic cilia

Hairs growing from conjunctiva in eye

Treatment of ectopic cillia

En-block resection of the hair (inc. root and surrounding tissue)

Causes of entropion in small animals

Anatomic defect

Secondary to condition causing globe retraction

Secondary to FHV-1 infection in cats

Treatment of entropion in dogs

Surgical - Hotz celsus

Ectropion

Outward rolling of eyelids

Treatment of ectropion

Surgical - shorten eyelid

Diamond eye

COmbination of entropion and ectropion

Treatment of upper lid trichiasis/entropion in cocker spaniels

Referal for Stades procedure

Treatment of eyelid tumours in dogs

Usually benign

Remove if growing or causing discomfort

Most common type of eyelid tumour in cats

Squamous cell carcinoma

Cherry eye

Prolapse of 3rd eyelid gland

Is cherry eye an emergency

No

Treatment of cherry eye

Surgical - pocket technique +/- anchoring sutures

Do not remove as can lead to dry eye

Is scrolling of the 3rd eyelid cartilage an emergency

No

Treatment of 3rd eyelid scrolling

Surgical removal of abnormal cartilage

Causes of conjunctivitis in dogs

Foreign bodies

Commensal overgrowth (staph, strep)

Allergies

Treatment of conjunctivitis in dogs

Antibiotics (Fuscidic acid/chloramphenicol)

Ddx for chronic conjunctivitis in dogs

Dry eye

Corneal ulceration

Glaucoma

Lens luxation

Uveitis

Causes of conjunctivtis in cats

FHV-1

Chlamydia

Mycoplasma sp.

Calicivirus

Treatment of conjunctivitis in cats

Symptomatic:

• Topical antibiotics

• NSAIDS

• FHV-1 = Famcyclovir/Gancyclovir

• Chlamydia = Doxycycline/Clavulanic acid amoxicillin

Causes of dry eye

IM destruction of lacrimal gland

Neurological damage

Trauma

Distemper

Endocrinopathies (e.g. diabetes mellitus)

Chronic conjunctival scarring (e.g. FHV-1)

Treatment of dry eye

Cyclosporin

Supportive care (Tacrolimus if no response in a few weeks)

Epiphora

Excessive tearing

How is tear film drainage checked

Fluorescein - wait for it to drain out of nose

Treatment of simple corneal ulcers

NSAIDs and topical antibiotics

Should heal in a week

Diagnosis of corneal ulcers

Fluoroscein
If deep ulcer, will not stain (down to Desmet's membrane)

Indolent corneal ulcers (SCCED)

Under-run the edge

Treatment of indolent corneal ulcers

Debridement (use cotton bud and work outwards from centre)
If still not healing can do keratotomy

When is a corneal ulcer defined as a deep ulcer

\>0.3mm

Treatment of deep corneal ulcers

Ofloxacin/gentamycin and serum/plasma drops q1-2h for 48h (hospitalise)

Analgesia

Collar to prevent scratching

Surgery if >5d or >5mm (conjunctival graft or transposition)

Melting ulcers

Proteases damage the conrea leading to a rapidly progressive ulcer

Treatment of melting ulcer

Serum and antibiotic drops

When should dogs with corneal ulcers get a re-check

5d (2d if brachycephalic)

Signs of uveitis

Red eye

Corneal oedema

Miosis

Decreased intraocular pressure

Pain

Loss of iris detail

Aqueous flare/hypopyon

Causes of uveitits

Deep/infected ulcer

Corneal trauma

Systemic infection/toxaemia

Neoplasia (primary or secondary to mammary carcinoma)

Infections - neospora, toxoplasma, leishmania, etc

Secondary to cataracts

Treatment of uveitis

Topical steroids/NSAIDs
+/- systemic antibiotics
+/- topical atropine for iris spasm

Uveal cysts

Dark discs within the anterior chamber

Diagnosis of uveal cysts

Can shine light through

U/S

Treatmet of uveal cysts

None unless affects vision

Anterior uveal melanoma

SOlid pigmented masses in the anterior chamber

Iris naevi

melanosis of the eye

Appearance of melanosis of the eye

'freckles' on the iris

Differentiating ocular melanosis from melanoma

Melanosis will not cause increased intraocular pressure or thickening

Signs of glaucoma

Red eye

Oedema

Pain

Blindness

Miasis and unresponsive pupil

Increased intraocular pressure

Is glaucoma an emergency

Yes (esp. if IOP \>50mmHg)

Pathophysiology of glaucoma

Obstruction of outflow

Open vs closed angle glaucoma

Closed angle = problem with drainage angle

Open angle = problem further along the drainage tract

Diagnosis of closed angle glaucoma

Goniolens to look at drainage angle

Causes of glaucoma

Primary drainage issue

Uveitis

Lens luxation

Tumours

Intraocular haemorrhage

Chronic retinal detachment

Abnormal pigment deposition

Treatment of lens luxation

Medical care if subluxated

Surgical removal if fully luxated

Treatment of glaucoma

Carbonic anhydrase inhibitors

Prostoglandin analogues (not if lens luxation)

Mannitol if IOP >50mmHg

Eosinophilic keratitis in cats

Due to FHV-1
'cottage cheese' opacities on cornea/conjunctiva

Treatment of eosinophilic conjunctivitis

Topical steroids +/- ciclosporin

Pannus

AI chronic superficial non-ulcerative keratitis in dogs

Often seen as ingress of blood vessels across cornea

Treatment of pannus

Topical steroids +/- ciclosporin

Treatment of corneal lipidosis

Usually self-limiting

Nuclear sclerosis

Thickening of lens (appears blue)

Normal ageing change (does not cause blindness)

4 types/stages of cataracts

Incipient = <15% of lens

Immature = 15-99% of lens

Mature = 100% of lens

Hypermature = lens liquefies

Diagnosis of cataracts

Direct ophthalmoscopy

Causes of cataracts

Inherited

Diabetes mellitus

Post-uveitis

Trauma

Radiation

Secondary to retinal degeneration

Treatment of cataracts

Control of secondary uveitis - monitor IOP

If mature can remove surgical (replace with plastic lens)

Do cataracts affect PLR/dazzle reflex

No

Appearance of vitreal degeneration

Multiple white opacities (often swirling)

What should be done to prepare for a retinal examination

Dilate pupil using tropicamide (wait 15min)
Darkened room

Collie-Eye anomaly

Non-progressive retinal disease - choroid vascular hypoplasia

Progressive retinal atrophy

Gradual photoreceptor degeneration = blindiness

Treatment of retinal detachment

Treat underlying cause (usually hypertension = Amlodipine)

What drug causes retinal toxicity in cats

Enrofloxacin

Treatment of corneal oedema

NaCl ointment 3-4x/d

Treatment of pigmentary keratitis

Treat underlying cause (e.g. entropion)
Same as for dry eye - ciclosporin

epibulbar dermoid

Congenital
Abnormally haired tissue in conjunctiva

Treatment of epibulbar dermoid

Surgical removal at 12w

Blepharitis

Ulceration of eyelids

Treatment of blepharitis

Systemic antibiotics
Steroids

Differentiation of ocular proptosis from glaucoma

Bilateral retropulsion (non-painful for ocular prolapse_

Causes of ocular proptosis

Retrobulbar abscess

Retrobulbar neoplasia

MAsticatory myosistis (usually bilateral)

Diagnosis of ocular proptosis

U/s (MRI/CT)

Treatment of retrobulbar abscesses

Drainage
Antibiotics
NSAIDs

Treatment of retrobulbar neoplasia

Enucleation and removal

Treatment of masticatory myositis

Prednisolone (+/- other immunosuppressants)

Ddx for sudden onset blindness

Glaucoma

Uveitis

Intra-ocular haemorrhage

Diabetic cataracts

Retinal detachment

Optic neuritis

CNS injury

Afferent and efferent nerves required for PLR

Afferent = CN II
Efferent = CN III

Does +ve PLR mean that there is no blindness

No - very few photoreceptors required for PLR = can still see response with large retinal damage

Afferent and efferent nerves tested by dazzle reflex

Afferent = CN II
Efferent = CN III and VII

Cranial nerves tested by the menace response

CN II, VI, VII

Why is the menace response not seen in puppies/kittens

Learnt response

Causes of intra-ocular haemorrhage

Inflammation (uveitis, retinitis)

Hypertension

Intra-ocular mass

Severe platelet disorder

Vascular abnormalities

Sudden acquired retinal degeneration

Rapid onset of bilateral blindness with no other pathology
Usually middle-aged female dogs

Diagnosis of sudden acquired retinal degeneration

Electoretinogram

Treatment of dacryocystitis (tear duct infection) in rabbits

Flush duct (use iv catheter)
Antibiotics
Dental if needed

Treatment of conjunctival overgrowth in rabbits

Ressection under GA