Non-Infectious Corneal Disorders: Cornea, Anatomy of Rx, Punctate Epithelial Erosions (SPK) & Thygeson SPK

Question 1

how many layers is the epithelium of the cornea?

what is it attached to?

Answer 1

6-8 cell layers,

attached to basement membrane

Question 2

where are the corneal stem cells located and where do they migrate?

Answer 2

located at limbus → migrate to central cornea.

Question 3

explain the afferent pathway of blink reflex

Answer 3

long ciliary → nasociliary → V1 → trigeminal ganglion → brainstem

Question 4

explain the efferent pathway of blink reflex

Answer 4

brainstem → CN7 → orbicularis oculi

Question 5

explain the afferent pathway of tear reflex

Answer 5

lacrimal → V1 → pterygopalatine ganglion

Question 6

explain the efferent pathway of tear reflex

Answer 6

greater petrosal → CN7 → lacrimal gland

Question 7

latent/inflammatory phase (4-8 hrs)

• mitosis stops at wound edge & damaged cells shed
• MMP-9 upregulation breaks cell adhesions (hemidesmosomes)
• cells develop filopodia (“foot” extensions) for migration

what stage of epithelial wounding healing?

Answer 7

stage 1

Question 8

cell migration (12-24 hrs)

• inflammatory response continues
• cells migrate in a monolayer close to wound to form X/Y suture
• cells start reestablishing hemidesmosomes

what stage of epithelial wounding healing?

Answer 8

stage 2

Question 9

adhesion & proliferation (24-36 hrs)

• cells continue forming adhesion complexes to Bowman’s layer
• cell proliferation reestablishes normal thickness & nerves regenerate
• a damaged basement membrane may slow this process

what stage of epithelial wounding healing is this?

Answer 9

stage 3

Question 10

what disorder do these cause?

dry eye, blepharitis, CL wear, lagophthalmos, etc.

Answer 10

punctate epithelial erosions (SPK)

Question 11

these clinical findings are indicative of?

tiny epithelial defects that stain w/ NaFl & Rose Bengal dye

• intercellular gaps due to tight junction loss
• damaged or dead epithelial cells

Answer 11

punctate epithelial erosions (SPK)

Question 12

clinical findings of inferior SPK indicative of

Answer 12

lagophthalmos, blepharitis

Question 13

clinical findings of defuse SPK indicative of

Answer 13

dry eye

Question 14

these treatments are for what disorder?

frequent lubrication w/ artificial tears; nighttime ointment

if pt wears CLs → discontinue use until epithelium heals

consider prophylactic antibiotics in CL wearers w/ significant SPK

Answer 14

SPK

Question 15

management: when do you see the pt back for SPK?

Answer 15

depends on severity, pt symptoms, ocular history, etc.

Question 16

describe anatomy of a prescription

Answer 16

• prescriber’s name required by law (address & phone number required for controlled substances)
• need DEA# to prescribe controlled substances
• pt’s name required by law (address & phone number required for controlled substances)
• date is required
• drug name (generic/brand), strength & type of delivery (topical solution/suspension, topical gel, oral)
• -specify strength if there are multiple strengths
• sig: # of doses, frequency, route
• disp: volume of bottle, quantity of day supply (for oral medications)
• indicate if the pt needs refills & how many
• initial box if you don’t want to substitute for a generic
• sign prescription w/ license number
• -NPI to save time for pharmacists

Question 17

these signs & symptoms are indicative of?

bilateral, irritation, mild, photophobia, vision blur, tearing, burning

Answer 17

thygeson superficial punctate keratitis

Question 18

clinical findings:

• coarse, elevated greyish epithelial lesions (usually around pupillary area)
• superficial lesions can stain w/ NaFl
• absent conjunctival hyperemia
• can have mild subepithelial haze

what describes these findings?

Answer 18

thygeson superficial punctate keratitis

Question 19

what is the management for?

• lubrication, restasis BID (long term),
• therapeutic (bandage) soft CLs
• topical steroid: loteprednol QID x 4 wks → very slow x 3-6 mo

Answer 19

thygeson superficial punctate keratitis

Question 20

what provides a protective layer over cornea to decrease continuous rubbing from the eyelid & to promote healing?

what if there is an epithelial defect?

Answer 20

bandage CLs

add a prophylactic antibiotic