Cornea 2: other disease and aterior uvea

• Be able to list the common causes of corneal opacities • Know how to recognise corneal melanosis and be aware of the role of medial canthoplasty in treatment of brachycephalic breeds, especially Pugs • Be able to recognise and treat CSK • Be familiar with the appearance and possible aetiology of crystalline stromal dystrophy and lipid keratopathy • Be familiar with needle retrieval of corneal foreign bodies • Anterior uvea  Be familiar with the function and examination of the iris and the autonomic control of the pupil diameter  Be familiar with the 3 main functions of the ciliary body  Know how to recognise iris atrophy, iridociliary cysts and benign iris melanosis  Have a basic knowledge of the appearance of primary neoplasia of the anterior uvea and the prognosis following enucleation  Be aware the lymphoma is the most common secondary neoplastic disease of the anterior uvea  Be able to recognise the signs of acute anterior uveitis

List common causes of corneal opacities 6

• Oedema

• Cells

• Blood vessels

• Pigment‐ corneal melanosis

• Disorganised collagen (scars from previous stromal injury)

• Lipid

how does odema cause corneal opacity

typicall yblue, steamy appearance. can be

• ulcerative: focal, fuorescein retension

• diffused, non ulcerative

  • Endothelial degeneration (age related) or dystrophy (breed-related)

    • not painful, not inflammed, normal IOP, no AF

  • Glaucoma, uveitis lens luxation (painful, red, abnormal IOP)

what type of cause would this odeama have

endothelail denegeration (age) or dystrophy (breed)

anterior uveitis —> cellular infiltrate

common cause of corneal opacities: cellular infiltrate. can be secondary to

white-yellowish appearance + keratitic precipitate

1. corneal ulceration: WBC from tear film, limbus, uvea via aqueous humous

2. immune-mediated keratitis

   • immune complexes deposited in visible clumps on the ventral corneal endothelium (gravity)

   • if there is uveitis present

anterior uveitis, where WBC aadhere to corneal endothelium. name this condition

: keratic precipitates

common cause of corneal opacities: what is this?

• acute or chronic?

• what is the different types? (2)

Blood vessel=Chronic pathology

Superficial —> ‘treelike’

Deep —> ‘hedgelike

common cause of corneal opacity

pigment

pug and BOAs dog predispose

common cause of corneal opacity

Disorganised collagen (scars from prev stromal injury)

this is a specular, crytstalline substance that is usually below the epithelium. what is this corneal opacity caused by

lipid depostion

Corneal melanosis aka

Pigmentary keratitis

Pigmentary keratitis is asssociated with ___ breed

pug/ BOAS

pigemntary keratitis can be due to (4)

Pigment carried from limbus along with new blood vewssels incresponse to corneal inflammation

• Increased corneal exposure / and trauma

  • eg macroplpebral fissure, prominent globe, Lagophthalmos

  • “ fall asleep w eye open”

• Reduced corneal sensation

• Keratoconjunctivitis sicca (KCS): chronic corneal desiccation

  • optimmune (cyclosporin a) can be prescribed to aid tear film production

• Entropion

look at this little guy! what procedure did they do and what did that correct?

medial canthoplasty.

• shortens the eyelids, reducing corneal exposure

• note reduction in the ‘scleral show’ after the procedure.

• often combined with a lower eyelid Celsus-Hotz to treat medial canthal entropion.

Chronic superficial keretits is also known as

breed disposition

pannus

GSD, Border Collie, Greyhound. young, middle aged

CSK typically originate form

lateral libus, but can occur medilly

CSK chronic superficial keratitis is charaterised by

• rough/cobblestone, fleshy, lymphoplasmocytic Inflammatory tissue

  • advances to the central cornea from the lateral limbus

• typically accompanied with blood vessels and sometimes pigment.

• corneal epithelium usually intact, TEL may be involved

• severe can lead to vision loss

name a factor for chroni superfical keratitis/ pannus

UV light exposure

Tx of chronic superficial keretitis

Immunosuppressive treatment:

• Ciclosporin twice daily

• +/- topical steroids as required

  • 4x daily for 2-4 weeks I

  • gradually reduce by 1 application every 2-3 weeks provided there is no deterioration in signs, maintain on ciclosporine

• Recurrence occurs with cessation of therapy.

corneal lipidosis

any disease in which corneal lipid deposition is a feature.

includes: Crystalline stromal dystrophy and lipid keratopathy

Crystalline stromal dystrophy

• primary, bilateral and inherited (but not congenital)

• well-demarcated central/paracentral grey/white crystalline opacities

  • composed of cholesterol, phospholipids and fatty acids.

• no pain or vascularisation associated, rarely progress and rarely effects vision.

• Treatment is not necessary

• (check for hyperlipoproteinemia if progress)

crystalline stromal dystrophy breed dispo

CKCS, Siberian Husky, Samoyed and Beagles

Lipid keratopathy

• lipid deposition secondary to another disease that causes corneal neovascularization

• Sometimes associated with hyperlipoproteinemia

• Topical steroids cause deterioration

• chronic—> Calcification and corneal degenerationcan

• epithelium usuallyintact but can —>corneal ulceration

Tx:Address underlying cause

• Keratectomy may be helpful in extensive or disconfort leision

• only if underlying cause is identified and addressed, prevent re establishment

corneal FB

• application of topical local anaesthetic (proxymetacaine) and flushing

• material removed by engaging with 23G or 25G needles (sedation/anaesthesia required).

• DO NOT grasp with forceps- push the foreign body further into the cornea.

• Full thickness foreign bodies —> operating microscope as corneal suture may be required

• full-thickness foreign bodies usually have a strand of fibrin adhered to their end—> specialist advice/referral

whtais an infdication of urgent referrla when FB present

tears in the lens capsule are present (the lens will need to be removed if the tear is large).

Poor prognostic indicators

• Penetration of the lens capsule

• Very large lacerations or extension of the laceration into the sclera

• Severe intraocular haemorrhage

Anterior uvea and posterior uvea

Anterior uvea – Iris – Ciliary Body

Posterior uvea – Choroid

The three layers of the eye

1. fibrous outer tunic (cornea, sclera),

2. vascular middle uvea (dark green‐iris, ciliary body, choroid)

3. neuroresensory inner layer (light green‐retina and optic nerve).

examinationof iris: mame area

MAC: major arterial circle

PZ: pupillary zone

IC: iris collarette

CZ: ciliary zone

parasympathetic causie pupil

constriction (miosis)

• constrictor contract, dilator relac

sympathetic causie pupil

filation (mydriasis)

• dilator contract

• constrictor relax

Anisocoria

different sized pupils

Miosis

constriction of the pupil

Mydriasis=

dilation of the pupil

pupil dilators used in clinic

Tropicamide: short acting parasympatholytic

• Ideal for diagnostic purposes

Atropine: long-acting parasympatholytic

• Can cause mydriasis for up to a week in a canine eye

• for therapeutic purposes

Anterior uvea, iris, pupil examination

• Pupil diameter

• assess size and symmetry

• Assess direct and indirect PLR

• Which pupil is abnormally constricted or dilated?

• What would you expect given the lighting conditions?

• animal stressed?

• Does miotic pupil dilate when you turn the lights off?