Ophthalmology

Question 1

what is the granula indica in the horses eye?

Answer 1

black pigment across pupil edge, thought to block sun

Question 2

function of slit lamp?

Answer 2

to determine depth of lesion in cornea and sometimes lens

cornea, front of lens, back of lens

Question 3

what is panoptic opthalmoscope?

Answer 3

between indirect and direct

Question 4

ophthalmic exam

Answer 4

1) angle of eyelids, external observation
2) before sedation
PLR
Dazzle reflex
menace response
palpebral reflex
corneal reflex
3) examine eye from outside to inside
cornea> pupil> lens, iris> anterior chamber> retina

Question 5

which nerve block can you use if horse wont let you see eye as keeps moving upper eyelid?

Answer 5

auriculopalpebral nerve block

Question 6

which nerve block blocks sensation to upper eyelid

Answer 6

frontal nerve block

Question 7

function of rose bengal?

Answer 7

assess tear film quality and margins of conjunctival and corneal neoplasia
fungal ulcers

Question 8

what midriatic should you use to dilate pupil

Answer 8

tropicamide

Question 9

common eyelid masses?

Answer 9

squamous cell carcinoma on 3rd eyelid
sarcoid- need wide excision margin
melanoma- not needed wide margin

Question 10

4 layers of the cornea

Answer 10

ESDE

epithelium
stroma- collagen cells
descement membrane
endothelium

Question 11

which type of ulcer is this

only damages epithelium.

tend to heal with no complications if tx
topical antimicrobial +.- topical atropine.
Healing rate 0.6 mm/ day . no corneal scar.

Answer 11

superficial ulcerative keratitis

Question 12

which type of ulcer is this

damages deeper stroma (collagen fibres). Tx: the same as for superficial. Pgx: scarring likely as different collagen fibres reform.

Answer 12

deep ulcerative keratitis

Question 13

what is keratomalacia

Answer 13

melting ulcer

Activation and/or production of proteolyic enzymes

Question 14

treatment for keratomalacia?

Answer 14

topical EDTA, acetylcysteine, tetracyline

Flunixin

Question 15

what sequalae of ulcer is this?
damage to level of DM. 
Dx: Flourescein negative!! 
Cx: Not necessarily very painful!! 
Tx: Aggressive therapy necessary: same as for deep melting ulcers 
Surgical therapy may be necessary

Answer 15

descemetocele

Question 16

Multiple, superficial, white, punctate or linear (dendritic) opacities. Varying (normally high) degree of ocular pain.

Dx: ± fluorescein ± rose Bengal.
Difficult to diagnose – Virus isolation and/or PCR (care: not accurate on its own).

Answer 16

Viral keratitis from EHV 2

Question 17

treatment for viral keratitis

Answer 17

topical aciclovir/ ganciclovir

Question 18

cake frosting appearance. Poor vascularisation of lesions

history of previous steroid treatment or antimicrobial failing.

May be -ve fluorescein initially but + rose Bengal. Cytology essential +/- culture

rare in UK, more USA hot and humid states eg south eastern states

Slow to resolve!

Answer 18

fungal keratitis

Question 19

tx of choice for fungal keratitis

Answer 19

vorinconazole

Question 20

insidious onset, immune mediated
Usually unilateral. No ulcer, breaks in epithelium
Slight ocular discomfort (no uveitis!)

BIG Vary from irregular corneal surface to deep bullae formation, vascularisation and oedema

Dx: fluorescein may be negative or slight uptake from breaks in epithelium

Answer 20

immune mediated keratopathies

Question 21

tx for immine mediated keratopathyies

Answer 21

topical corticosteroid, cyclosporine A or doxycycline

Surgical: keratectomy, cyclosporine A implant

Question 22

Pain: blepharospasm and epiphora – angle of eyelash pointed down.

Chemosis: red eye

Constricted pupil – essential sign

Aqueous flare: milky appearance of anterior chamber – essential sign

May have: Blood (hyphaema), pus (hypopyon) or fibrin in anterior chamber

anterior or posterior uveitis?

Answer 22

anterior

Question 23

Pain variable (often very mild)
Vitritis
Retinal changes
Typically diagnosed late in the course of the disease

anterior or posterior uveitis?

Answer 23

posteiror

Question 24

tx for uveitis

Answer 24

• Topical corticosteroid (if no ulcer present)
• Topical NSAID? (if ulcer present)
• Topical antimicrobial? Not needed. Leptospirosis component only causes immune response, not direct infection in eye.
• Topical atropine (c/4h until pupil dilates should last longer time than day) Danger: if bullae open possibility of systemic absorptiongut stasis/ colic!!
• Systemic NSAID: Flunixin > Phenylbutazone
• Surgery – Suprachoroidal Cyclosporine A implant: rmild cases, reduces inflammatory response – Pars plana vitrectomy – Enucleation

Question 25

how to diagnose cataracts

Answer 25

Retroillimination cataract shows as dark on tapetal

Direct focal illuminaton (= transillumination) • Dire

Question 26

surgical tx for cataracts

Answer 26

phacoemulsification

Question 27

what drug is contraindicated in glaucoma?

Answer 27

prostaglandins

Question 28

pain not as big as in other spp 
Hydrophthalmos or buphthalmos 
Corneal oedema 
Corneal striae – striation due to stretching of descment membrane 
Lens luxation – if persists 
Blindness

Answer 28

glaucoma

Question 29

tx for glaucoma

Answer 29

topical dorzolamide (Carbonic anhydrase inhibitor)

Topical Timolol ( betablocker)

Also can use antiinflamms eg NSAIDs, corticosteorids

Question 30

surgical tx of glaucoma

Answer 30

o Laser destruction of ciliary body
o Aqueous shunts
o Enucleation

Question 31

normal appearance of optic nerve

Answer 31

oval and salmon pink

Equine retina paurangiotic : 30-60 vessels radiate from optic nerve

Question 32

normal colours of 
Neurosensory retina 
Retinal pigmented epithelium
Tapetum
Choroid:
Sclera:

Answer 32

Neurosensory retina – clear cling film
Retinal pigmented epithelium – black but may or may not be pigmented
Tapetum – variable colour- blue, green, amber
Choroid: red
Sclera: white