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KMK Ocular Disease > 10 - Cornea4 > Flashcards

10 - Cornea4 Flashcards

1
Q

Terrien’s marginal degeneration

  • who
  • pathophys
A

Rare, men, 20-40yo

IDIOPATHIC non-inflammatory degeneration
Slowly progressive PERIPHERAL STROMAL THINNING -> perforation (15%)

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2
Q

Terrien’s marginal degeneration

-signs/symp

A

Signs: SUPERONASAL, bilateral, slowly progressive thinning, assoc vascularized pannus

Symp: asymptomatic; progression can cause irreg astig, decr VA

*Mooren’s can app similar but with overlying epi defect

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3
Q

Salzmann’s nodular degeneration

  • who
  • pathophys
A

Rare, females, 6th decade

Episodes of keratitis -> degenerative dz
Assoc with SIGNIFICANT CORNEAL INFLAMMATORY DZ (incl mgd, trachoma, phlyctenulosis, vkc, dry eye, ik)
-can also be idiopathic

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4
Q

Salzmann’s nodular degeneration

-signs/symp

A

Signs: HYALINE plaque deposits b/w epi and BOWMANS, classically app as mid-periph, elev, BLUE-GRAY or yellow-white nodular lesions

  • can be uni/bilat, single/multiple
  • often located within/adjacent to old corneal scar/pannus

Symp: asymptomatic; pain if RCEs develop, vision reduced if nodule is within visual axis

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5
Q

While limbal girdle of vogt

  • epidemiology/hx
  • signs/symp
A

Very common, age-related: 55% of pts 40-60, nearly 100% over 80

Bilateral chalk-like linear opacities of nasal limbus (3/9 o’clock)
Asymptomatic

*degen of collagen, sometimes with calcium

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6
Q

Band keratopathy

-pathophys/assoc condns

A

Ocular: trauma, chronic inflammation/ocular surf dz

  • uveitis/JIA
  • dry eye
  • exposure k

Systemic: incr serum CALCIUM or PHOSPHORUS levels

  • GOUT (check uric acid levels)
  • hypercalcemia/hyperparathyroidism
  • sarcoid
  • renal failure (check BUN, creatinine)
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7
Q

Band keratopathy

-signs/symp

A

Signs: Ca2+ deposits on anterior surface of BOWMANS, app as white spots with SWISS CHEESE pattern, most concentrated within interpalpebral cornea

Symp:

  • usually asymptomatic: Ca2+ plaques at 3/9 o’clock
  • uncommon: plaques move centrally -> FBS, decr vision
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8
Q

Arcus senilis

  • who
  • pathophys
  • signs
A

Most common corneal opacity: almost 100% over age 80
Higher incidence in males, black

Assoc with AGE, HIGH CHOLESTEROL
Lipid deposition BEGINS ON DESCEMETS -> bowmans -> stroma

Bilateral, symmetric, 1mm band in periph cornea with clear zone of separation to limbus
Unilateral is rare - assoc with CAROTID DZ on side WITHOUT the arcus
Younger than 50 assoc with incr risk of CAD (run lipid profile)

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9
Q

Crocodile shagreen

  • pathophys
  • signs/symp
A

Irregularly arranged folds of collagen

Signs: BILATERAL, GRAY-WHITE, POLYGONAL stromal opacities (“cracked ice” app)
-either:
—near BOWMANS layer = ANTERIOR
—near DESCEMETS membr = POSTERIOR

Symp: asymptomatic + benign

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10
Q

Corneal farinata

A

Bilateral “FLOUR DUST” deposits located in CENTRAL DEEP STROMA
Due to aging, AD condn
Asymptomatic

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11
Q

Corneal graft rejection

  • how common
  • type of response
  • layers
A

30% within one year

TYPE 4 HS RXN

Epithelial: rare; elevated, irregular epi
Stromal: subepi infiltrates known as KRACHMER’S SPOTS
Endothelial: charac by WBCs on endo that form KODADOUST LINE

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12
Q

Refractive surgery

  • absolute contraindications (4)
  • relative contraindications (5)
A

Absolute:

  • under 18 yo with unstable RE within last year
  • unrealistic expectations
  • ocular dz: keratoconus, active HSV, contact lens warpage
  • systemic dz: CT dz (e.g. keloid formers), collagen vascular dz, immunocompromised (e.g. chronic steroid use)

Relative:

  • ocular dz: blepharitis, dry eye, chronic eye rubbing, osd, large pupils
  • diabetes mellitus - 3mo stability required
  • POAG: if not well controlled, due to elevation during procedure with suction cup placement
  • pregnancy
  • retinal thinning/lattice degen: incr risk of retinal tears
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13
Q

Refractive surgery

-contact lens wearers need to be out of them how long prior

A

Soft spherical: 3-14 days

Soft toric + RGP: 14-21 days

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14
Q

Refractive surgery

-radial keratotomy

A

Radial incisions made with DIAMOND KNIFE to flatten peripheral stroma -> normal IOP pushes weakened area outward -> reduced myopia

NO LONGER PERFORMED due to better options
-significant instability, PROGRESSIVE HYPEROPIC SHIFTS

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15
Q 
Refractive surgery
-photorefractive keratectomy 
—procedure
—candidates/tx range
—healing
A

Removal of epi, BOWMANS, superficial stroma (no flap) -> excimer laser to cornea
-vs lasik: bowmans -does not regen, kept in lasik; less post-op dryness, requires less corneal thickness, cheaper

Ideal for PTS AT RISK FOR TRAUMA (military, athletes)
-no risk of flap complications
Tx range: -8 to +4D, up to 4D cyl
400um residual cornea reqd

Longer healing time (1-2 weeks) bc entire epi must regrow

  • extremely poor vision + pain post-op (given nsaids, bcls)
  • risk of stromal haze reduced with mitomycin C during procedure
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16
Q 
Refractive surgery
-LASIK
—procedure basics
—tx range/requirements
—healing
A

Laser-assisted in situ keratomileusis
Epi flap made with MICROKERATOME -> excimer laser to ANTERIOR STROMAL BED -> flap reattached

Range: -10 to +4D, up to 5D cyl
-clear lens extraction can be performed for those exceeding requirements
Thickness requirements: 250um residual
-flap itself = 150um
-ablation depth = 12um per D

Heal faster (1-2 days), less pain + post-op haze vs prk

17
Q

Refractive surgery
-LASIK
—femtosecond laser flap

A

Used instead of microkeratome
E.g. Intralase

FS flap: thinner (avg 100um), removes risk of mechanical malfunction, assoc with less post-op dry eye

18
Q

Refractive surgery

  • LASEK
  • epi-LASIK
A

Laser epithelial keratomileusis
Same procedure as lasik, but flap is made with DILUTE ALCOHOL

Version of LASIK where a BLUNT PLASTIC BLADE creates the flap

19
Q 
Refractive surgery
-conductive keratoplasty
—who
—procedure
—tx range
A

PRESBYOPES, low hyperopes, residual astigmatism after previous sx

RADIO FREQUENCY energy to SHRINK COLLAGEN FIBERS in peripheral stroma -> central steepening
-regression expected in 2-3yrs, can be repeated

+0.75 to +3.00D, less than 0.75D cyl

20
Q 
Refractive surgery
-intrastromal corneal rings (Intacs)
—who
—procedure
—tx range
A

KERATOCONUS

PMMA rings inserted into peripheral stroma -> flatten cornea (shortens corneal arc length)

-0.75 to -3D (no hyperopes)

21
Q

Refractive surgery
-clear lens exchange
—procedure
—tx range

A

Cataract sx without cataracts
No residual accomm remains (unless MFIOL used)

Large range

22
Q

Refractive surgery
-phakic IOL
—procedure
—tx range

A

“Implantable contact lens”
Intraocular lens implanted in PHAKIC eyes
-angle-supported, iris-supported, or sulcus-supported
-requires a peripheral iridotomy

Large range of errors, preserves natural accomm

23
Q

Refractive surgery
-astigmatic keratotomy
—procedure

A

Corneal incisions with DIAMOND BLADES to relax cornea in STEEPEST MERIDIAN

24
Q

Refractive surgery
-wave-front guided/custom corneal surgery
—procedure

A 
Reduces HOAs (coma, spherical) + corrects RE (LOAs)
Can be done with LASIK/PRK - theoretically better contrast + acuity, less glare
25
Q

Refractive surgery

-successes

A

Generally considered 20/40 or better
90-99% with low RE get this
~75% achieve 20/25 or better

26
Q

Refractive surgery

-LASIK complications (9)

A

1) Pain in first 24hrs - wound, flap complications (severe)
2) serious infection - esp days 1-3, gram(+)/mycobacteria
3) flap complications
4) corneal ectasia - esp high myopes, anytime after sx
5) residual RE - esp > -8D, loss of BCVA in 1%
6) glare - small ablation zone, large pupil, monovision
7) dry eye - MOST COMMON SE (33%)
8) diffuse lamellar keratitis
9) epithelial ingrowth

27
Q

Refractive surgery
-LASIK complications
—types of flap complications (4)

A

Button hole: cap perfortion/hole in flap, esp very steep corneas or deep set eyes

Free caps: no hinge made, esp very flat corneas

Flap folds: almost half occur in 1 hour, 95% within 1 week

  • macrostriae = full-thickness with undulating, parallel stromal folds, slippage or mal-positioning during sx
  • microstriae = fine, irreg, multi-directional folds in Bowmans, resolve on own

Flap dislodgement: more common with keratome flaps, due to accidental touch to eye/lid

28
Q

Refractive surgery
-LASIK complications
—type of dry eye caused

A

Secondary, non-sjogren’s, aqueous-deficient due to corneal nerve severing

Often improves in 1-2mo

29
Q

Refractive surgery
-LASIK complications
—diffuse lamellar keratitis

A

aka sands of the sahara

Rare, inflammatory, non-infectious reaction at the lamellar interface (b/w corneal flap + stroma)
Fine, granular, sand-like infiltrate 2-3 days after sx
May be response to toxins
-less common with disposable microkeratomes

Symp: asymptomatic; photophobia, blur, FBS, pain, vision loss (scarring/melt)

30
Q

Refractive surgery
-LASIK complications
—epithelial ingrowth

A

Slow: 1mo post-op

Faint grey line or white, milky deposits within 2mm of flap-edge interface

Asymptomatic

MOST COMMON COMPLICATION ASSOC WITH LASIK ENHANCEMENT

31
Q

Refractive surgery

-retreatment criteria

A

Earliest at 3mo, prefer 6mo

Astig: >0.75D + symptoms
RE: >/= 0.75D from target in unhappy pt
Uncorrected VA of 20/30 or worse in unhappy pt

KMK Ocular Disease (17 decks)

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