Ophthalmology Flashcards
what is the granula indica in the horses eye?
black pigment across pupil edge, thought to block sun
function of slit lamp?
to determine depth of lesion in cornea and sometimes lens
cornea, front of lens, back of lens
what is panoptic opthalmoscope?
between indirect and direct
ophthalmic exam
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
which nerve block can you use if horse wont let you see eye as keeps moving upper eyelid?
auriculopalpebral nerve block
which nerve block blocks sensation to upper eyelid
frontal nerve block
function of rose bengal?
assess tear film quality and margins of conjunctival and corneal neoplasia
fungal ulcers
what midriatic should you use to dilate pupil
tropicamide
common eyelid masses?
squamous cell carcinoma on 3rd eyelid
sarcoid- need wide excision margin
melanoma- not needed wide margin
4 layers of the cornea
ESDE
epithelium
stroma- collagen cells
descement membrane
endothelium
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.
superficial ulcerative keratitis
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.
deep ulcerative keratitis
what is keratomalacia
melting ulcer
Activation and/or production of proteolyic enzymes
treatment for keratomalacia?
topical EDTA, acetylcysteine, tetracyline
Flunixin
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
descemetocele
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).
Viral keratitis from EHV 2
treatment for viral keratitis
topical aciclovir/ ganciclovir
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!
fungal keratitis
tx of choice for fungal keratitis
vorinconazole
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
immune mediated keratopathies
tx for immine mediated keratopathyies
topical corticosteroid, cyclosporine A or doxycycline
Surgical: keratectomy, cyclosporine A implant
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?
anterior
Pain variable (often very mild)
Vitritis
Retinal changes
Typically diagnosed late in the course of the disease
anterior or posterior uveitis?
posteiror
tx for uveitis
- 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 absorptiongut stasis/ colic!!
- Systemic NSAID: Flunixin > Phenylbutazone
- Surgery – Suprachoroidal Cyclosporine A implant: rmild cases, reduces inflammatory response – Pars plana vitrectomy – Enucleation
how to diagnose cataracts
Retroillimination cataract shows as dark on tapetal
Direct focal illuminaton (= transillumination) • Dire
surgical tx for cataracts
phacoemulsification
what drug is contraindicated in glaucoma?
prostaglandins
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
glaucoma
tx for glaucoma
topical dorzolamide (Carbonic anhydrase inhibitor)
Topical Timolol ( betablocker)
Also can use antiinflamms eg NSAIDs, corticosteorids
surgical tx of glaucoma
o Laser destruction of ciliary body
o Aqueous shunts
o Enucleation
normal appearance of optic nerve
oval and salmon pink
Equine retina paurangiotic : 30-60 vessels radiate from optic nerve
normal colours of Neurosensory retina Retinal pigmented epithelium Tapetum Choroid: Sclera:
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
