Cornea and External Dz Flashcards
what is the mainstay treatment of pinguecula?
AT’s
What are indications to remove pinguecula?
cosmetically unacceptable, chronic inflammation (can try short course of steroid drops), and if interferes with wearing contact lenses
pterygium. what’s the most common age, gender, population, position on eye (why?)
most common in 20-30 men, along the equator, mostly nasally as it’s theorized that the shadow of the nose prevents corneal refraction to temporal side.
what are concretions?
conjunctival epithelial inclusion cysts that are filled with keratin debris and mucopolysaccharide and mucin.
what is stocker line?
a pigmented line of iron deposition at the invasive border of a pterygium.
Indications for pterygium removal
cosmetic
inducing astigmatism, invasion of visual axis/blurry vision
constricting eye movements
Chronic inflammation–can try short course of steroids but not long term
what are the three muscles and respective innervations for eye lids?
orbicularis oculi: innervated by CNVII
Levator palpebrae: CN III
Muller muscles by symmathetic nerves
what is avg blinking rate?
10-15
What kind of glands are Glands of Moll
apocrine sweat glands
What kind of glands are Glands of Zeis
modified sebaceous glands
what are the afferent and efferent components of the lacrimal functional unit (LFU)?
CN V nociceptors on the ocular surface. to brain stem then efferent to meibomian gland, lacrimal gland, and goblet cells.
what does the caruncle attach to?
plica semilunaris
what is the blood supply of bulbar conj?
anterior ciliary arteries of the ophthalmic artery
conj associated Lymphoid tissue (CALT) is located where?
substantia propria of the conj
cornea contributes to roughtly how many % of the total refractive power?
74%
how thick is the corneal epithelial layer? what are the three components?
40-50 microns thick. superficial squamous, broad wing cells, columnar basal cells (1 layer)
Basal epithelial cells secrete a basement membrane of 50 nm thick. what kind of collagen is it?
Type IV
what is the make up of bowman’s layer?
it’s an acellular condensate to the anterior stroma
How thick if bowman’s layer?
15 microns
What’s the purpose of bowman’s layer?
help to maintain shape of cornea
what are the major collagen and proteoglycan components of corneal stroma?
Collagen: type I, V fibrillary collagen interwoven with Type IV
Proteoglycans: decorin and lumican
What % is water in corneal stroma?
78%
what are the components of corneal hydration?
Na-K ATPase, swelling pressure of cornea due to glycosaminoglycans, and IOP compression, epithelial evaporation
where is the Dua’s layer of cornea?
predecemet’s layer