Ophthalmology: Corneal Refractive Surgery

Question 1

Radial Keratotomy

Answer 1

Corneal reshaping with deep radial slices

• NEVER FDA approved and no longer performed*
• (only 60% corrected to 20/20 and major problems, to include myopic changes at altitude)*

Question 2

PRK

Answer 2

Photo refractive keratectomy

• Epithelium removed, then stromal ablation based on refractive error*
• First performed in 1987, FDA approved 1995*

Question 3

Limitations to PRK

Answer 3

Thickness of cornea (550 um)

At least 350 microns residual cornea required (each diopter shaves 12-20 microns)

Question 4

LASIK

Answer 4

Laser Assisted In-Situ Keratomileusis

• “laser ablation under a corneal flap”*
• iLasik = infrared laser flap creation (versus metal keratome)*

Question 5

PRK and LASIK FDA limits (not Navy limits)

Answer 5

Myopia up to -14D

Hyperopes up to 6D

Cylinder to +/- 4D

Question 6

Contraindications to Refractive Surgery

Medical Conditions

Answer 6

Autoimmune

Collagen-Vascular

Immunodeficiency Diseases

Diabetes

Sign of keratoconus

Pregnant/nursing

Relative contraindications: dry eye, ocular allergies, ocular HSV/HZV

Question 7

Contraindications to Refractive Surgery

Medications

Answer 7

Isotretinoin (Accutane)

Amiodorone

Question 8

PRK vs LASIK

Answer 8

Question 9

Risk and Complications of PRK/LASIK

Answer 9

• “Spectacles” (not a guarantee to be glasses free)
• Dry eye
• Infection/Inflammation
• Haze (PRK)
• Flap complications (LASIK)
• Loss of BCVA

Question 10

Grading of PRK Haze

Answer 10

Trace

1+, 2+, 3+, 4+

Note: waiver required for 1-4

Question 11

True/False

LASEK is the same as LASIK

Answer 11

False

“E” refers to Epithelial removal prior to laser ablation (aka PRK)

Question 12

iLASIK

Answer 12

IntraLase laser LASIK

• Laser created flap (no metal knife), decreased flap complications, better flap architecture*
• Note: most centers use this method now*

Question 13

WFG-iLASIK

Answer 13

Wavefront Guided (WVG) “custom” ablation

Decreased optical aberrations, fastest recovery time

Question 14

ReLEx SmILE

Answer 14

Refractive Lenticule Extraction Small Incision Lenticule Extraction

“Flapless IR laser lenticule”

Myopic treatment only

Question 15

ICL

Answer 15

Implantable Collamer Lens

Silicone lens places behind iris

Question 16

True/False

ICL is approved for all aviators

Answer 16

False

Only for Class II-IV (waiver required)

Question 17

True/False

ICRs are NOT approved for aviation (any class)

Answer 17

True

Note: ICR = intrastromal corneal ring, not ICL

Question 18

Refractive Surgery Advantages

Answer 18

Improved vision under Gz

Improved detection of other aircraft

Improved landing/runway detection in low contrast

Reduction of canopy glare

Question 19

PRK Aviation Applicants NCD Limits

Answer 19

SNA: +3.00 to -8.00 D

Class II - IV: +6.00 to -8.00 D

No more than 3.00 D cylinder or 3.50 anisometropia

Note: 6 month wait after surgery for civilian applicants

Question 20

LASIK Aviation Applicants NCD Limits

Answer 20

SNA: +3.00 to -8.00 D

Class II - IV: +6.00 to -8.00 D

Designated applicants/aviation students = up to 6 D astigmatism

No more than 3.00 D cylinder for applicants