6: cornea, sclera - giuliano Flashcards
t/f
an appropriate Tx for ulcers are topical steroids
false
NEVER put steroids on a corneal ulcer
what are 5 conditions that considered an ophthalmic emergency?
keratitis [corneal ulcers] uveitis [hyphema] glaucoma [acute 1*, 2* to lens luxation] orbital dz [proptosis] adnexae [eyelid lacerations]
what does a rose bengal stain evaluate for?
FHV-1
KCS
what CrNn does palpebral reflex require?
CrN 5 and 7
important things to consider while describing corneal ulcers:
size depth position relative to limbus health of surrounding cornea chrnoicity / cause # of ulcers
what is the significance of the position of the ulcer relative to the limbus?
if ulcer is deep, it needs neovascularization which comes from the limbus
so if near limbus, that is good
if positioned too centrally and far from the limbus, may recommend Sx instead
underlying causes of corneal ulcers:
trauma (save for last) FB eyelid abnormalities infectious etiologies neurologic defect KCS*** congenital abnormalities
underlying infectious causes of corneal ulcer in cats:
FHV-1
1* infection common
underlying infectious causes of corneal ulcer in dogs:
1* infectious keratitis does not ‘typically’ occur
r/o all other causes 1st in dogs (KCS)
2* infection may result in progressive ulceration, stromal malacia, perforation
what neurologic deficits will be present w CrN 5 issue?
sensory deficit, neurotrophic keratitis
what neurologic deficits will be present w CrN 7 issue?
lagophthalmos
superficial corneal onset typical presentation?
acute
what tissue layers are lost in superficial corneal ulcer?
what does this look like on fluoroscein stain?
epithelial tissue loss only
stroma intact
sharp distinct borders to stain
minimal corneal inflammatory response b/c acute
what is reflux uveitis?
axonal reflex mediated by CrN 5 w release of inflammatory mediators (PG)
cornea richly innervated so if nerve ending abrasion, signal sent back to uveal tract [PG mediated response] -> ciliary spasm and uveal tract spasm to close the eye
simple corneal ulcer Tx:
- find and remove underlying cause
- px 2* infection - broad spectrum topical abx
- tx refulx uveitis (atropine, oral NSAIDs)
- px self trauma (e-collar)
- NO topical corticosteroids
- recheck 7 d
what is SCCED?
spontaneous chronic corneal epithelial defect
what is an indolent ulcer?
SCCED - a superficial ulcer that should heal but does not heal
chronic or likely to become chronic
minimal corneal inflammatory effect - epithelium tries to cover the defect but cannot adhere
what tissue is lost in an indolent ulcer?
what does the STT look like?
epithelial loss only - stroma intact
non-adherent epithelial “lip” - creates indistinct borders with stain - “halo” like effect
tx of indolent ulcers?
px 2* infection promote healing - topical anesthetic, debride, perform grid keratotomy or diamond burr keratectomy tx reflex uveitis px self trauma recheck 7-10 d
for indolent ulcers, what is believed to be the problem that is preventing healing?
corneal anterior stromal problem
with just a dry q tip debridement, what % of indolent ulcers will heal?
50%
how do you do a grid keratotomy?
what species is it appropriate for?
what % will heal?
make hash marks in superficial cornea - get through anterior stroma so epithelial cells have more healthy stroma to adhere
use 27 gauge needle***
85% heal
dogs
why is grid keratotomy NOT appropriate for cats and horses typically?
the MC cause for feline and equine is infectious - you will inoculate the deeper tissue w the bacT => BAD
what abx for indolent ulcers?
oxytet
terramyciin
atropine - to effect - to dilate pupil
oral NsAID oral analgesic (tramadol)
if the grid keratectomy does not repair the indolent ulcer, what should be done?
refer
may need superficial keratectomy
or 2nd grid keratotomy or corneal thermal cautery
what is a descemetocele?
a deep ulcer = complex ulcer = melting ulcer = deep stromal ulcer
what are the characteristics of a stromal ulcer?
- acute or chronic
- epithelial AND stromal tissue loss
- fluorescein stains walls and floor of ulcer
- stroma frequently unhealthy: edema, inflammatory cells, “melting” or keratomalacia
what is appearance of deep corneal ulcer?
- severe corneal edema {blue}
- variable depth of stromal loss
- soft, melting corneal stroma
- yellow-cream stromal infiltrates
- corneal neovascularization
- anterior uveitis {hypotony, miosis, equeous flare, hypopyon or fibrin in AC}
what are causes of deep ulcer?
- endogenous proteinases [WBCs, corneal epithelial cells, stromal fibroblasts]
- 2* bacT infections [collagenase prod, B-hemolytic strep]
- topical corticosteroids [local immune suppression, potentiation of collagenase activity]
what does the Seidel test evaluate for?
if concerned that patient might still be actively leaking
put fluorescein stain on eye and do not dilute it, wait, then if positive, you will see the leak
dx of deep corneal ulcer:
corneal cytology and swab [under anesthesia]
be careful and DO NOT touch eyelids
swab margin of ulcer bed
deep ulcer Tx?
- find and remove underlying cause
- Px / Tx 2* infection - assume already infected
- Tx reflex uveitis
- px corneal melting: serum
- bandage
- Sx?
- e collar
- recheck w/in 7 d
what does serum do to help ulcer heal?
anti collagenase activity
surgical options for deep ulcer tx:
conjunctival graft
corneo-conjunctival transposition
REFER
when should Sx be considered for deep ulcer?
greater than 1/2 stromal depth loss
rapidly progressive or melting
no neovascular response
perforated and actively leaking
medical mgmt of deep ulcer?
- abx based on cytology and culture
g + = cefazolin
g - = fluoroquinolone - use solutions - NOT ointments
what is the function of proteinase inhibitors in deep ulcer Tx?
inhibit endogenous and BacT collagenases
px melting or Tx ongoing stromal melting
when should atropine be used?
initially - to maintain pupillary dilation => Px synechia [iris adhering to other tissue]
cycloplegia for ciliary M spasm assoc w reflex uveitis
stabilize blood-eye barrier via dec vasc permeability
when is systemic therapy appropriate to Tx deep ulcers?
appropriate for deep ulcers
analgesic
systemic anti inflammatory
systemic abx - if perforation possible and to px ascending infection
Sx Tx of deep ulcer?
conjunctival graft [pedicle]
corneal graft
ophthalmic tissue glue
t/f
a conjunctival graft will restore vision completely in a patient with a deep ulcer
false
will restore functional vision but not complete vision
what is a corneal facet?
chronic ulcer hx: deep ulcer that healed
intact epithelium, healthy tissue but still thin and is a defect - an area of weakness
how long does debridement take?
hours
how long does epithelial flattening and migration take?
hours
how long does epithelial mitosis take?
days
how long does basement mem deposition take?
days to weeks
how long does stromal collagen deposition take?
days to weeks
how long does stromal collagen remodeling take?
months
what are 3 reasons an ulcer will NOT heal in 7-10 days?
- original cause still present
- it has become infected
- it is an indolent ulcer
what is the sclera?
white of the eye
part of the outer fibrous tunic
what are the specialized areas of the sclera?
limbus
intrascleral venous plexus
equatorial extra ocular muscle insertions
lamina cribrosa
what is the lamina cribrosa?
exit of optic nerve - it is the axons of ganglia cells
MC scleral dzz?
coloboma
neoplasia
immune med disorders
trauma
what is a sclera coloboma?
a hole in the scleral tissue
ddx for brown pigment in the sclera?
melanoma
benign melanocytoma
what can you visualize with gonioscopy?
the irido corneal angle
what is NGE?
etiology?
episcleritis and episclerokeratoconjunctivitis => nodular granulomatous
immune mediated
NGE MC seen in what species and breed?
collies and collie crosses
Tx of NGE?
top and sys steroids
top cyclosporine
sys tetracycline
sys azathiopirne
what is predominate cell type present in NGE?
macrophages
