Ophthalmology Module 1 Flashcards
What CN nerves are used in PLRs
CN 2 & 3
What cranial nerves are involved in menace reponse
CN 2 & 7
What cranial nerves are involved in the dazzle reflex
CN 2 & 7
What cranial nerves are involved in the palpebral reflex
CN 5 & 7
What is proptosis
Acute forward displacement of the globe with entrapment of the eyelids
What can cause proptosis
Blunt trauma, bite on the head, brachycephalics (predisposed due to shallow orbits)
What are prognostic indicators with proptosis
Good: If there is movement of the eye, if PLRs are present (posterior segment of eye intact)
Bad: 2 or more avulsed muscles, compromised globe due to scleral rupture
What are methods for fixing proptosis
Lubricate, cleanse, temporary tarsorrhaphy and may need lateral canthotomy
What aftercare should be give post temporary tarsorraphy?
Antibiotics (chloraphenicol, triple abs, oxytet), broad spectrum abs, systemic corticosteroids at anti-inflam doses, remove sutures
complications for proptosis
blindness (20-28% regain vision due to stretching of optic nerve), strabismus, sensory deficit to cornea, KCS, exposure kertatitis, cataract formation, lens luxation, phthisis bulbis
What is ophthalmia neonatorum?
Neonatal conjunctivitis - syndrome of acute conjunctival inflammation in neonates - FHV -1 in cats, staph, fecal contaminants
How do you treat ophthalmia neonaturum?
Irrigate with saline or dilute iodine, BS antibiotics 4-6 times daily and constant lubrication
how can ulcers be classified
depth of corneal involvement, superficial, stromal, descemetocele, perforation
What are the basics of superficial ulcer management
- Treat inciting cause
- Topical abs - flora on epithelium not present on stroma so will sent up infection
- Pain control: conreal pain receptor stimulation can results in uveitis (tropicainamide, atropine)
- E-collar
Stromal ulcer management
- Ab therapy - fluoroquinolone + chloramphenicol every 4 hrs
- Topical atrophine (one dose per 12-24 hrs for 1-2 days)
- Topical anti-proteinase - anti-collagenase - 1-2 hrs till healing under way and then 4-6 hrs
- Systemic pain relief
Corneal perforation management
- E-collar
- Systemic abs and pain relief
- topical abs
- Surgery - flaps v. enucleation
What does corneal laceration treatment depend on?
If less than 50% - Treat as an ulcer
If more than 50% surgical management and referral
What is glaucoma?
A group of ocular diseases that result in progressive retinal ganglion cell death and optic nerve degeneration
How is IOP determined?
IOP is determined by AH production verse outflow
Where and how is the aqueous humor produced?
It is produced in the posterior segment by the non-pigmented epithelium of the ciliary body. Circulates from ciliary body to pupil and then to anterior chamber
- Principle mechanism of AH formation is through active secretion (80-90% of AH) this is catalysed by carbonic anhydrase (50-60%)
- Diffusion
- Ultrafiltration
Ways of AH outflow
Conventional outflow: Travels from anterior chamber to iridiocorneal angle and ciliary cleft to reach the venous system
Unconventional outflow: small percentage of AH is also drained by stroma of iris, ciliary body and choroids to reach the venous system
Glaucoma classifications
- Congenital - development abnormalities in AH flow route
- Primary - changes in iridiocorneal angle - hereditary/bilateral (open/close/narrow) 4-10yrs presentation
- Secondary - disease that blocks iridiocorneal angle
Acute glaucoma treatment
- Prostaglandin analogues (Latanoprost, Travoprost) - not if lens luxation or secondary to anterior uveitis
- CAIs - first line in cats
- Timolol - topical beta-blocker to use in cobo with CAI
- Mannitol
What is uveitis? what types are possible?
Inflammation fo uveal tract - iris, ciliary body and choroid
Anterior uveitis
Posterior uveitis
Pan uveitis
also acute, subacute and chronic
If untreated what can result due to acute uveitis?
development of permanent structural lesions that may result in - secondary glaucoma, cataracts, retinal detachments
What are DDX for red, painful eyes
glaucoma, corneal ulceration, scleritis, uveitis
How to treat uveitis?
- Topical AI therapy - steroids once ulcer ruled out 3-6 times daily (pred acetate)
- Topical AI therapy - NSAIDs (can be used concurrently) 6-12hr - can be used with ulcers if concurrent uveitis
- parasympathlytic drygs - atropine, tropicamide
Why is atropine useful for uveitis?
Pain relief: Paralyses ciliary body and causes mydriasis
Minimises posterior synchiae forming (adhesions between vitrous and lens capsule)
Decreses intraocular inflammation by blocking acetylcholine
not for glaucoma
Causes of hyphema
Trauma
Infection/uveitis
neoplasia
immune-mediated
coagulopathy
congenital ocular disease
Lens luxation classification
- Congeital - lens instability caused by abscence of zonular gibers
- Primary luxation: inherited zonular defect, 3-6yrs old, bilatearly disorder
- secondary: caused by hypermature cataracts, chronic glaucoma, neoplasia
- Feline lens luxation: secondary to uveitis or glaucoma
Lens luxation treatment - anterior worst
- Topical CAI
anterior lens lux - AVOID prostaglandin analogues - removal of lens surgically
- if not surgical dilate pupil and drop lense into posterior chamber
Causes of acute blindness
- Lesions that produce opacification of the ocykar media
- Lesions that cause failure of the retina to process the image
- Lesions that impede transmission or relay of message through the visual pathways
- Lesions that cause failure of the final processing of the image in the visual cortex
