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BCSCSAP Review > Refractive Surgery > Flashcards

Refractive Surgery Flashcards

1
Q

Diagnosis

A

epithelial ingrowth

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2
Q

When can epithelial ingrowth be observed?

A

peripheral nests of epithelial cells

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3
Q

What is keratophakia

A

central lamellar keratectomy with placmement of a plus-powered lens intrastromally

corrects hyperopia and presbyopia

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4
Q

occurs 10 years after radial keratotomy (RK)

A

progressive hyperopia

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5
Q

What change in an arcuate keratotomy procedure might result in overcorrection

A

incision placed at a smaller optical zone

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6
Q

Candidate for LASIK?

A

No, KCN is CI to refractive surgery

(inferior steepening on corneal topography)

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7
Q

Why is laser refractive surgery CI in patients with poorly controlled connective tissue dusorders? Examples

A

unpredictable wound healing

SLE, RA

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8
Q

Are collagen vascular diseases an increased risk of ectasia

A

NO!

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9
Q

Stromal bed thickness (RSB) in which ectasia are more likely to occur

A

less than 250 um, however thicker RSB is not a guarantee that ectasia will not develop

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10
Q

Pregnancy and refractive surgery

A

Wait 3 months after delivery and cessation of breastfeeding

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11
Q

Diagnosis

Treatment

A

Stage IV Diffuse Lamellar Keratitis

lifting the LASIK flap, irrigating, starting corticosteroid drops

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12
Q

Stage 1 DLK

A

scattered interface opacities in the periphery

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13
Q

Stage 2 DLK

A

scattered interface opacities centrally

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14
Q

Stage 3 DLK

A

scattered interface opacities that have coalesced

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15
Q

Stage 4 DLK

A

corneal scarring or melting

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16
Q

Treatment for Stage 3 and 4 DLK

A

lifting flap, irrigating, intensive topical corticosteroid treatment

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17
Q

Disorder that disrupts Placido disk-based topography measurements of the corneal curvature

A

DRY EYE

quality of the air-tear film interface

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18
Q

Risk factor for myopic patient undergoing refractive lens exchange with a monofocal lens

A

increased risk of retinal detachment

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19
Q

Definition of nanophthalmos and risk factors

A

AL < 18mm

choroidal detachment

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20
Q

High myopia

A

axial length of 26 mm or greater

risk for RD

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21
Q

Biomechanical property of cornea is responsible for greater effect of refractive ablation under lamellar flap compared to surface ablation

A

nonuniform load

(200 lamellae of collagen fibrils; packing is denser in anterior 2/3 of cornea

anterior also stronger because of differences in glycosaminoglycans

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22
Q

When offering monovision who desires near and distance vision. What refractive error differential typically provides a well-tolerated balance of distance and near vision

A

Dominant eye: distance

Non-dominant eye: target of -1.25 D to -2.50 D

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23
Q

Clinical trials on conductive keratoplasty have found what on the long-term effectiveness and stability of this procedure

A

Regression was found in treatment of hyperopia and presbyopia

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24
Q

Piggyback lenses developes a visually significant interlenticular membrane. Treatment?

A

removal of lenses

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25
Q

Interlenticular membranes occur between these types of implanted lenses

A

2 acrylic IOLs, especially if both implanted in capsular bag

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26
Q

Corneal inlays are approved by the US FDA for treatment of what condition?

A

early to moderate presbyopia

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27
Q

What characterizes pressure-induced stromal keratitis (PISK)?

A

It is a steroid response with elevated IOP after LASIK

28
Q

Diagnosis

Treatment

A

Pressure-induced stromal keratitis

(figure) fluid cleft in the flap interface resulting in artificially low pressure when checked by applanation.

Tx: rapid tapering or D/C steroid drops and starting IOP lowering drops

If untreated -> results in severe glaucomatous visual loss

29
Q

Orthokeratology involving overnight use of RGP lenses can help with temporary reduction of what problem?

A

low amounts of myopia (up to -6.00 D)

low astigmatism 1.75 D

30
Q

What feature is commonly found in patients with LASIK flap macrostriae

A

Macrostriae involve the full thickness of the LASIK flap

31
Q

Diagnosis

A

macrostriae

occur when a LASIK flap is not positioned correctly or slips postoperatively

involve FULL-THICKNESS undulating stromal folds of lasik flap

32
Q

mechanism of femtosecond laser interaction with tissue

A

photodisruption

33
Q

Expected in infectious keratitis but not diffuse lamellar keratitis

A

infectious: inflammation extending beyond the flap edge. 2-3 days s/p LASIK

DLK: infalmmation at periphery of flap decreases towards center

34
Q

Binocular diplopia s/p LASIK

A

decompensated phoria

35
Q

Keratometry readings that result in poor-quality vision after refractive surgery

A

<34.00D and higher than 50.00 D

36
Q

Why are IOL calculations difficult to accurately obtain in someone who has had laser refractive surgery?

A

Relationship between anterior and posterior cornea has changed

37
Q

MOA KAMRA corneal inlay for near vision

A

pinhole effect

38
Q

Diagnosis

Definition

A

Diffuse lamellar keratitis (DLK) is a sterile inflammatory response seen in flap interface after LASIK

Cause: response to variey of mechanical and toxic insults

39
Q

What post-IOL implantation complication is less likely

A

RARE: cataract formation

Common: endothelial cell loss, glare, starbursts, halos

40
Q

Primary difference between femtosecond lenticule extraction (FLEx) and small-incision lenticule extraction (SMILE)

A

flap creation

SMILE - femtosecond, avoids flap

FLEx - femtosecond, flap

41
Q

Tx for this condition

A

Buttonhole s/p LASIK

replacement of flap and bandage contact lens

attempt LASIK after 3 months with thicker flap or PRK

42
Q

Myopic patient shows 1.5 D more myopia on wavefront measurement than on MR. Why?

A

Patient is accommodating during analysis

Should be within 0.75 D of each other. If not, repeat

43
Q

post-LASIK myopic shift with onset of with-the-rule astigmatism

A

post-LASIK ectasia

44
Q

Patient with free cap after attempted cutting of LASIK flap, what treatment would you recommend?

A

Place corneal cap in moist chamber and proceed with tretment if stromal bed is large enough

BCL placed until endothelial pump can secure cap

45
Q

Excimer laser removes corneal tissue by what light-tissue interaction, what wavelength of light

A

Photoablation; 193 nm

argon-fluoride excimer

46
Q

IOP in post-LASIK patient

A

true IOP may be higher

(Goldman assumes CCT of 520 microns)

47
Q

Increased rate in spherical aberration in patients with postoperative keratometry in these values

A

less than 34.00 D or greater than 50.00 D

48
Q

Tx for persistent epi defect following PRK

A

punctal occlusion

49
Q

Waelength of energy when applied to cornea is characterized by high energy and precision, low penetration of tissue and limited thermal spread

A

193 nm

Highly suitable for ocular surface - photoablation

50
Q

transforms tissue into plasma with high pressure and temperature and leads to rapid tissue expansion

A

femtosecond laser generates 1053 nm

51
Q

Wavelength of collagen cross-linking

A

365 nm (ultraviolet A)

52
Q

wavelength and laser-tissue interaction of Holmium-YAG laser

A

2.13 um - photothermal effect

53
Q

How does conductive keratoplasty affect the cornea

A

it works by increasing the curvature of the central cornea

54
Q

Material intrastromal corneal ring segments are made from

A

polymethyl methacrylate (PMMA)

55
Q

how long should patients be advised to avoid using rigid contact lenses

soft CL?

A

3 weeks for RGP

2 weeks soft toric

3 days to 2 weeks for soft CL

56
Q

1 week s/p PRK.

Diagnosis

A

sterile infiltrates

AW postoperative CL use and topical NSAID drops

57
Q

Inadequate suction is mostly to cause what complication during construction of a LASIK flap with mechanical microkeratome?

A

an incomplete flap

58
Q

To improve vision associated with myopic astigmatism caused by post-LASIK corneal ectasia, what is an appropriate initial option

A

rigid gas-permeable contact lens

59
Q

gold standard for correction of reduced vision due to ectasia

A

RGP contact lenses

60
Q

used to reduce the incidence of corneal haze after PRK

A

mitomycin C

61
Q

1 month s/p bilateral LASIK 25 yo M c/o 3-days pain and redness

Treatment?

A

Lift LASIK flap and obtain cultures - including fungi and mycobacterium

(note: K infiltrate, diffuse haze under flap, hypopyon suspicious for post-lasik microbial keratitis

62
Q

Major differences between arcuate keratotomy (AK) and limbal relaxing incisions (LRIs)

A

Arcuate incisions are made at a greater relative corneal depth

made in midperiphery (7-9 mm optical zone)

63
Q

Role of vitamin B2 in corneal crosslinking

A

Riboflavin (Vitamin B2) generates singlet oxygen and superoxide anion free radicals

64
Q

Variable affects the depth of laser ablation required to treat a given degree of myopia

A

optical zone diameter

Munnerlyn formula

Ablation Depth (um) ~Degree of myopia (D) x (optical Zone diameter)^2 (mm)/3

65
Q

Condition alloplastic corneal inlays are used to treat

A

presbyopia

66
Q

Cx a/w posterior chamber phakic intraocular lenses (IOLs)?

A

endothelial cell loss

Cataract formation, endothelial cell loss, RD - all reported in patients who undergo posterior chamber phakic IOLs

BCSCSAP Review (13 decks)

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