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
what structure is the “end” or edge of decement’s membrane
schwalbe line
vertical and horizontal diameter of cornea in adults?
vertical 10-11; horizontal 11-12
which nerve innervates the cornea?
long ciliary nerve forms sub epithelial plexus
what technique can be used to visualize endothelial cells
specular microscopy
do endothelial cells proliferate?
not in vivo. damaged areas are covered by enlargement of surrounding cells.
structure hosting stem cells for corneal epithelium?
palisade of Vogt
what is the XYZ hypothesis of corneal health?
X is proliferation and stratification at limbus, Y is centripetal migration of epithelial cells centrally, Z is desquamation of old corneal cells. For K to be healthy X +Y >Z
triad of KPs, elevated IOP, and corneal edema indicates what?
HSV
cyclosporins are associated with what side effect?
disc edema
what side effect is associated with Etanercept and Infliximab
optic neuritis
Kpro biggest two down sides?
risk of glaucoma and endophthalmitis
severe atopic dermatitis and keratoconjunctivitis can be treated with what oral med LONG term?
tacrolimus
chronic cicatricial conjunctivitis signs? differential?
fornix fibrosis and shortening.
infection (adeno, trachoma), mucus membrane pemphegoid, trauma/chemical injury, neoplasm
features of vernal conjunctivitis
<10 y/o M, giant papilla, horner-trantas dots (limbal follicles)
topiramate is associated with glaucoma. what are the 3 primary treatments?
stop topiramate, topical hypotensives, cycloplegia (for often associated mild AC raection)
azithromycin has what side effect?
QT prolongation
how to treat gonococcal conjunctivitis? what if there’s corneal involvement?
conjunctivitis 1g ceftriaxone IM.
if there’s corneal involvement–admit pt for IV ceftriaxone
what is specular microscopy?
confocal microscopy live imaging of endothelium.
whats the normal density of endothelial cells
1500-3500 cells/mm2
what is confocal microscopy of the cornea good for?
in vivo analysis of the 5 layers. can identify causative organisms of infection, corneal nerve morphology, eval of each layer in dystrophies
what are the 4 main zones of the cornea?
central, paracentral, peripheral, limbal
what are the three key components giving cornea its optical properties
shape, curvature, power
what is the optical zone of the cornea
cornea overlying pupil
what is cornea apex vs cornea vertex?
apex is the point of max curvature, vertex is point at intersection of patient’s line of fixation and corneal surface.
whats the average refractive power of the cornea?
+43D; +49D from anterior surface -6D of posterior surface
what is keratometry and what does it measure? limitation?
measurement of power of central cornea. It calculates radius of curvature in mm.
only measures anterior power of central cornea
what is keratoscopy?
projection of placido rings to provide qualitative information of the entire anterior cornea
what is topography vs keratoscopy?
topography is digitally projected and represented with colors
bow-tie pattern on topography?
astigmatism
crab claw configuration on topography is classic for what? what else is on differential?
pellucid marginal degeneration, or keratoconus is also ddx.
what is angle kappa? what is a desired value when calculating IOLs
angle between visual axis and pupillary axis (optical axis). want it to be <0.4mm
what should you avoid if angle kappa is >0.4?
multifocal IOLs. given line of sight and pupillary axis (optical axis) are far apart
what is corneal tomography vs topography? what technology is tomography based on ?
tomography can capture 3D structures of the cornea–anterior and posterior curvature, corneal thickness, AC depth, lens information.
-placido and scanning slit
what filter is used to see fluorescein
cobalt blue
what is dye disappearance test?
timing duration of fluorescein presence –if prolonged there may be nasal lacrimal system blockage.
punctate staining at 3 and 9 o’clock is classic for what cause
due to CL wear
what is the basic secretion test?
filter strip 5mm wide 30 mm long, in fornix with anesthetic–to measure basic tear production; <3mm in 5 mins is abnormal
what is schirmer I test–how is it done and what does it test for? what’s abnormal
filter strip to fornix withOUT anesthetic to test for basic AND reflex tearing. <5.5mm in 5 mins is Abnl.
what is schirmer I test–how is it done and what does it test for? what’s abnormal
filter strip to fornix withOUT anesthetic + nasal mucosa irritation with cotton tip. <15 mm in 5 mins is Abel
comment on specificity and sensitivity of schirmer tests
specific but NOT sensitive
whats the normal osmolality of tear
306-308
what are some markers of dry eye that we can assay for ?
lactoferrin, IgE (for allergic), matrix metalloproteinase 9 (MM9) >40
what is corneal esthesiometry and how is it done?
corneal sensation test–> cotton whisp without anesthesia, before IOP check, and tested in all 4 quadrants
There’s also a handheld esthesiometer (cochet-Bonnet)
what is corneal hysteresis
the difference in pressure of the cornea bending inward vs bending outwards during air jet applanation
What is corneal resistance factor?
correction between corneal hysteresis and thickness.
terrien marginal degeneration classic features?
marginal corneal thinning with lipid keratopathy in 4-5th decade of life resulting in against the rule, oblique, or irregular astigmatism.
patient population for floppy eye lid
obese with OSA
underlying problem with floppy eyelid
lax upper tarsus
recurrent corneal erosions. what are 3 causes?
past trauma, past HSV, epithelial dystrophy
treatment options for recurrent erosions?
lubricate/hypertoic saline, BCL, epithelial debridement vs anterior stromal puncture, PTK vs PRK
what is distichiasis?
two rows of eye lashes (second coming out of meibomian glands
what is mucus fishing syndrome
patients fixated on fishing strands of mucus out of eye and eye rubbing leading to more mucus production. +lissamine green and rose bengal inferior K and conj
what is congenital anterior staphyloma?
opaque cornea that is partially or completely absent of decemet’s and endothelium and lined with uveal tissue posteriorly to cornea causing iris problems. usually unilateral
what is keratectasia and how is it different than congenital anterior staphyloma?
keratectasia is opaque cornea without decemet’s or endothelium. Anterior staphyloma has also a layer of underlying uveal tissue that keratectasia does not.
which IOP lowering drop is associated with reactivation of HSV keratitis?
prostaglandin analogues
microcornea dimensions? mode of inheritance? px?
<10 mm; autosomal dominant. px generally well with glasses
megalocornea dimensions? mode of inheritance
> 13mm; sex linked recessive
megalocornea associated gene?
CHRDL1
megalocornea associated abnormalities?
diaphany, goniodysgenesis, ectopia lentes, arcus, zonule instability, glaucoma (not congenital glaucoma.
dimensions of cornea plana and sclerocornea?
<43 D
Cornea plana is associated with what gene?
KERA(12q22)
ocular associations of cornea plana?
close angle glaucoma, cataract, coloboma, hyperopia
Finnish ancestry is associated with what disease
cornea plana
3 waves of neurocrest cell migration at 6 weeks make up what structures
K endothelium, stroma, and iris
mode of inheritance for sclerocornea?
sporadic is most common.
manifestation of syphilic intrauterine keratitis?
typically 6-12 years old; sudden onset K edema, vascularization formation of salmon patch that regresses to leave ghost vessels
Association of Lowe’s syndrome?
oculocerebrorenal. cataract, kidney disease, and corneal keloid
corneal keloids are seen with what conditions?
Lowe’s, Rubinstein-Taybi, ACL (acromegaly, cutis vertices gyrata, corneal leucoma syndrome)
forceps birth trauma is associated with what eye findings
Horner’s and Vertical Haab’s striae.
What is congenital corneal anesthesia?
bilateral sterile ulcers and PAINELESS K opacities as infant or child.
what’s the difference between degeneration and dystrphy
dystrophies has inheritance pattern
deceit’s thickness at birth and in elderly?
3 microns –>13 microns
what are age related Guttate called?
Hassall-Henle bodies; due to loss of endothelial cells.
What are coat’s white ring
residual subepi/stromal haze after metal FB. It won’t change after acute inflammation has resolved…so no use for steroid at this point