Cornea Flashcards
(34 cards)
In come people the corneal dendritic scar (with bulbous ends) heals, but what are some of the complications that could arise for those who dont heal?
if the infection is confined to the epithelium, healing occurs without scarring.
Sometimes stromal inflammation may occur and so this can lead to some level of scarring.
anterior uveitis can occur
what can happen if you put a topical steroid on a herpetic corneal ulcer?
results in an amboeid ulcer and is slow to heal and very hard to treat.
what are some complications of herpes zoster virus?
conjuctivitis
keratitis
anterior uveitis
scleritis and episcleritis
What are three viruses that can affect the cornea?
herpes simplex
herpes zoster
adenovirus
WHat are predisposing factors that make bacterial infection likely to happen in the cornea?
corneal trauma
contact lens wear
chronically compromised ocular surface such as dry eye, blepharitis and keritopathy
hepatitis keratitis
corneal exposure (facial nerve palsy (cant close eyes) and proptosis)
immunosupression, including topical steroid use
what is the management for bacterial keratitis?
urgent investigation and admission!
conjuctival and corneal samples sent for microscopy and culture
broad-spectrum topical antibiotics such as quinilone, are administered frequently 24 hrs per day, intially until a favourable response is seen.
sometimes subconjuctival and systemic antibotics are given
despite the liklihood of permanent scarring topical steroids are only used when resolution of the infection element.
what is marginal keratitis?
blepharitis is a common cause of marginal corneal ulceration which is a hypersensitivy reaction to bacterial toxins - NOT an infection
what are the three types of corneal transplantation one can do?
penetrating keratoplasty - full thickness
deep anterior lamellar keratoplasty - partial thickness leaving endothelium in place
endothelial keratoplasty - just the endothelium is transplanted
what causes corneal melting?
infection
reduction of tear flow
autoimmune process
sx of adenovirus keratitis?
blurring and photophobia after viral conjuctivits
What is recurrent corneal erosion syndrome?
caused by epithelial or stromal dystrophy or by previous trauma
what are some systemic associations with cataract?
diabetes
corticosteroid therapy
hypocalcemia and other metabolic disorders
what are the three types of cataracts that can develop?
nuclear scelrosis - central opacity
posterior subscapular - back of capsule
cortical - spoke like opacities of the cortex
What are some caused of leukocoria? (white pupil)
cataract retinoblastoma retinopathy of prematurity corneal opacity coat's disease
what is ectopia lentis?
a disolcated lens - causes include trauma, marfans, cataract
WHat is the difference between open and close angle glaucoma?
Open-angle is when there is an open and wide angle between iris and cornea, develops over a very long time and symptoms are not always known.
Angle-closure is when there is a closed and sharp angle, happens quickly and symptoms are very obvious.
When the block is at the entrance it is called Closed Angle Glaucoma. When the blockage is not at the entrance, but beyond, somewhere inside, we call it Open Angle Glaucoma. Closed angle is assosciated with a pupillary block.
WHat are the sx of close angle vs open angle glaucoma?
open angle:
not much
closed angle: pain, nausea and vomiting loss of vision red eye (usually unilateral) cloudy cornea a hx of a previous attack
what is the surgical procedure for open vs closed angle glaucoma?
open-angle: trabeculectomy
closed-angle: iridotomy
How can you test if there is a pupil sympatehtic problem?
cocaine test - 4% cocaine solution into eye and if pupi does not dilate (which a normal one would) then this indicates a loss of sympathetic innervation.
What is denervation hypersensitivity?
This is when postganglionic fibers are damaged and so the iris creates more receptors and therefore reacts to a smaller concentration of neurotransmitters than it normally should
How can you test for denervation hypersensitivity?
postganglionic parasympathetic lesions - pilocarpine 0.1% - affected pupils will constrict while normal pupils will not
postganglionic sympathetic lesions - 0.1% adrenaline - affected pupils will dilate while normal won’t.
how are the pupils affected in third nerve palsy?
dilated pupil that fails to react to light.
also has ptosis and down and out eye.
What is Adie’s pupil?
damaged postganglionic parasympathetic fibers causes a semi dilated pupil that reacts poorly to direct light and to accommodation. redilation is slow.
cause unknown - likely viral???
diagnosed with hypersensitivity to 0.1% pilocarpine.
What is Horner’s syndrome?
miosis, ptosis and anhydrosis
most obvious in a dim room when the horner’s eye fails to dilate.
cocaine 4% dilates the normal pupil but not the horner’s one. whereas adrenaline 0.1% dilates the horner’s pupil but not the normal one. (since cocaine only prevents reuptake of adrenaline)
investigate for a pancoast tumour in the lung.
