Ophthalmology Laser And Surgery

Front 1

Malignant hyperthermia:

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mortality < 10%; triggered by succinylcholine, halothane, enflurane & isoflurane; 2/3 have elevated creatine phosphokinase; early=tachy or elevated end tidal CO2, unstable BP, tachypnea, sweating, rigidity, cyanosis, dark urine; late=temp rise; Tx=dantrolene to prevent Ca release from SR in muscle cells, cooling, hydration, hyperventilation, bicarbonate for acidosis

Front 2

Botox:

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inhibits Ach release from presyn terminal
Uses: blepharospasm, acute lat rectus palsy complication: ptosis

Front 3

most common reason for failure of RD repair

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PVR

Front 4

of the types of Retinal detachmends, which has the Best prognosis

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RRD due to dialysis or small round hole, chronic RD w/ demarcation line, minimal SRF

Front 5

what is a relative contraindication for Pneumatic(c3f8 or sf6) RD repair

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Chronic RD

Front 6

which gas for RD repair has the shortest duration;

Back 6

Air

Front 7

PVR

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reattachment & visual outcome worse with SF6 compared to oil or C3F8; outcome for C3F8=oil for both initial & subsequent surgeries; post op pucker is common after both gas & oil

Front 8

what is the prognosis for repair of Aphakic RD

Back 8

Moderate prognosis

Front 9

C3F8 (propane)

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very high surface tension; loses effect if very large tear or tear under very high traction; longest lasting (50% after 3 wks)

Front 10

SF6

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has highest expansile rate (watch IOP!)

Front 11

Perfluorocarbon liquids

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high SpGr—heavier than water-->steam rolls giant tears, draining choroidals, repositioning dislocated IOLs; toxic to retina (due to compression) after 24-48 hrs & immediately toxic to AC

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Octane-

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very high vapor pressure—readily evaporates in gas filled eye (safer-—see perfluorocarbon liquids above)

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Silicone

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very viscous; very low surface tension (all gases are higher)—therefore if aqueous makes it through viscosity (very tough to do) it can more easily seep into tear; SpGravity is less than waterbuoyant; good for complicated cases as it “compartmentalizes” inflammation in eye; Inferior PI necessary to prevent pupil block

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CO2 laser

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infrared (wavelength=10.6 microns); absorbed by water -> temp increase-->cell destruction

Front 15

SLT

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biologic response (release of cytokines-->mac recruitment-->IOP reduction)

Front 16

which laser would you use for PRP through VH or very dense NS

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Krypton red

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ALT

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if initially effective then wears off, repeat will be successful in 33-50% but 10-15% have sustained elevated IOP

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Xenon arc

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disadvantage: unfocused polychromatic white light emission w/ considerable blue light emission (harmful to retina & lens), more pain, increased risk of bruchs break-->chroidal effusion & CNVM

Front 19

which laser would you use for PRP through a clear medium

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Argon

Front 20

Trab: anti-fibrinolytics are indicated for ???

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previous failure, aphakia, pseudophakia, NVG

Front 21

Post op Choroidals

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Risk factors: high preop IOP (>30), aphakia, pseudophakia, myopia, prior vtx, glaucoma, athersclerosis, HTN, prior episode; ?decompress before opening globe, close w/ nylon sutures, Good intraop BP control

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peristaltic

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speed of rollers allows linear (rapid) control of vacuum

Front 23

diaphragm

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inlet & outlet valvesslower vaccum build

Front 24

venturi

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most rapid rise in vacuum

Front 25

PMMA lenses

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hydrate prior to insertion as packaging creates static & retains dust debris

Front 26

Viscoelastic:

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dispersive: higher retention; fragments in high vaccumdifficult to remove; protects corneal endothelium

Front 27

Cutler-beard flap

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replaces full thickness defect of upper w/ full thickness flap from ipsilateral lower lid

Front 28

Hughes bridge flap:

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transposes bridge flap of tarsus & conj into defect

Front 29

Post op CME:

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incidence is <1%; angiographically is about 10%

Front 30

Scleral sutured PC IOL

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pass needle 0.75 mm post to limbus

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DCR

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stoma created at level of middle turbinate most often w/in 10mm of cribriform plate; most common reason for failure=obstruction at common canaliculus or bony ostomy site

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LASIK:

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dec stromal haze, rapid epi healing, increased endophthalmitis; post op flap folds occur w/in first week (>50% on d1 & >90% w/in 1st wk)

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Post op diffuse lamellar keratitis

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(“Sands of the sahara”) typically presents w/in 1st week; early==tx=steroid w/ good prognosis; later WBC clump in visual axis & flap must be lifted for irrigation, intense PF gtts & PO steroiods

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PRK:

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reduced endophthalmitis, reduced corneal perf, increased pain
(epithelium is removed after alcohol saturation)

Front 35

RK

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Radial corneal incisions: greatest effect when placed near visual axis, local flattening w/ flattening 90D away, increased length=increased effect; 50% tensile strength of normal cornea

Front 36

Munnerlyns formula

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ablation depth=diopters/3 x (optical zone(mm))2; best for <7D

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Intracorneal rings

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used for mild myopes, complications: decr K sens > K perf; <10% change >1D over 1 year; K positive asphericity is maintained; +reversible

Front 38

LASEK

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similar haze to LASIK
similar procedure to PRK, however, after alcohol, epi is folded & replaced on eye at end of case (no flap though)

Front 39

open sky procedures

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keep positive vit pressure low via hyperventilation

Front 40

Lamellar keratoplasty

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low risk of haze (???contradicted in MEEI p. 276 #378); only useful if endo is healthy: Terriens marginal degen, desmetocele, pellucid marginal degen, Salzmann’s nodular degen, superficial scars, Reis bucklers, K-ulcer perf; (NOT Lattice as lattice involves deep stroma)

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PK:

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in kids: smaller graft to dec ant bulge of lens-iris diaphragm & dec peripheral synechiae; early suture lysis decreased NV of graft
@ 1 year, 90% are clear (65% on HSV eyes); 20% risk of endo graft rejection

Front 42

poor prognosis after PK

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active inflammation, stromal NV, youth, glaucoma, larger grafts, dry eyes, hypesthesia

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Best prognosis after PK

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lack of NV, lack of inflammation, lack of h/o of prior graft rejection, adult

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Most common indication for PK In children

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Peters

Front 45

Most common indication for PK in adults

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Pseudophakic bullous keratopathy

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+recurrence in graft

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lattice, macular, Reis buckler, HSV, granular

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Rejection following corneal transplant

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1st time=10 days; 2nd occurance ~7d; early finding=Khoudadoust line (linear KPs); graft rejection spares host corneal bed; DDx: acute incr IOP, Vit/K touch

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Endo/stromal rejection:

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emergency (aggressive topical & systemic steroids); may be instigated by suture removal, IOL lasers;

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Epi rejection:

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much less severe, may look identical to EKC subepi keratitis