The Effects of Refractive Surgery on the Carrier Landing Grades of Naval Aviators

Ashley Lesley, MD, LCDR MC(FS) USNRRandy Birt, OD, LCDR MSC USN

Naval Hospital Lemoore andUniversity of California Davis Eye Center

The opinions and views expressed are those of the authors and do not represent official Department of Defense policy or position.

This study was supported by the United States Navy.

We have no other financial disclosures to report.

Aviation Physical Standardsfor new students

•Defined by Naval Aerospace Medical Institute•Strict requirements to begin training•Rigorous physical examination, many

seemingly healthy candidates do not qualify•Eye exam makes up fully 50% of criteria

NAMI Eye Exam (includes topography)

•Distance UCVA >20/100 OU▫Prior to 2006 UCDVA 20/40 or better

•Refractive limits •No more than -1.50 in any meridian•No more than +3.00 in any meridian

•No eso/exophoria > 6.0 PD or hyperphoria >1.5 PD•All tropias disqualifying•Normal color vision and stereovision• IOP <22 mm Hg

U.S. Navy Aeromedical Reference and Waiver Guide, Physical Standards - 5.

PRK Accessioning Study• Internal study started in 2000• Initially 400 aviation applicants

– Naval Academy students had PRK at National Naval Medical Center in Bethesda, MD

– Officer candidates could obtain PRK at outside facility at their own expense

• Determined students post-PRK performed comparably in initial flight training (12 week initial qualifying course)

• History of refractive surgery remains disqualifying but waivers now granted for a history of PRK

PRK Waiver Guidelines

Pre-op CRx -8.00 to + 3.00 D sph < 3.00 D of cyl

Waiver may be submitted no earlier than– 3 months for < -6.00 SE– 6 months for > -6.00 SE– 6 months for hyperopia

Must meet established aviation vision standards post-operatively

U.S. Navy Aeromedical Reference and Waiver Guide, Ophthalmology, 19-23.

Clinical question• Do aviators with uncorrected visual acuity

perform better than aviators who have had refractive surgery?

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Study Design

• A training squadron (VFA-125) for the F/A-18C “Hornet, ” a tactical strike/fighter platform is located at NAS Lemoore, CA

• Carrier qualification done at the end of training syllabus• 10 carrier landings during the day• 6 carrier landings at night

• Receive Day, Night, and Total GPA• Day, Night, and Total Boarding Rate (BR)

• Boarding rate is a percentage of successful landings• Unsuccessful landing means that aircraft misses wires,

must take off again, and try to land again• All passes graded by panel of Landing Signals Officers (LSO)

who are qualified pilots, on a standardized scale of 0.0-4.0

Study Design

• Pilots identified from Training Squadron (VFA-125)– Physical exams from NAMI’s database in Pensacola, FL reviewed– Carrier qualification scores taken from squadron Training

database– Identified all students from FY 2004 to 2008

• 16 pilots with history of PRK prior to CQ• 22 pilots required spectacle correction for CQ• 79 pilots with 20/20 OU uncorrected for CQ• All between ages of 25 and 32• All in excellent health without systemic illness

Results

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Variable PRKGroup Mean

With CorrectionGroup Mean

Without CorrectionGroup Mean

P-value(Noninferiority)

Day Landing GPA 2.86 2.90 2.87 0.032

Day Boarding Rate 92.56% 91.86% 89.72% 0.028

Night Landing GPA 2.81 2.85 2.88 0.033

Night Boarding Rate

83.19% 87.68% 85.44% 0.165

Total Landing GPA 2.84 2.88 2.87 0.054

Total Boarding Rate 87.81% 89.32% 87.53% 0.002

Conclusions

• Equivalence shown in Day GPA, Day Boarding, Night GPA, and Total Boarding by non-inferiority p-value

• Test of difference failed to showed significance in Night Boarding and Total GPA

• No significance shown in p-value for the same references

• Night Boarding and Total GPA are then equivocal• No trend in our data suggests a difference in CQ

performance in aviators with a history of PRK• Allowing PRK has opened naval aviation to applicants

who would not have met standards• Has allowed the Navy wider recruiting

Future of Refractive Surgery• LASIK Aviator Retention Study now enrolling

designated personnel– Good clinical results so far in non-pilot aviators

• Concern about LASIK flap and ability to tolerate excessive G-forces

• Quicker return to full duty than with PRK• Several years until applicants with LASIK arrive at

the Training squadron and study can be repeated• VFA-125 has been retired so must be repeated

with another squadron

U.S. Navy Aeromedical Reference and Waiver Guide, Ophthalmology 19-23.

ReferencesCloud, David S. “Perfect Vision is Helping and Hurting Navy,” New York

Times. June 20, 2006.Franklin QJ, Tanzer, DJ. Late Traumatic Flap Displacement after LASIK.

Military Medicine. 2004 Apr;1969(4): 334-6.NAVAIR 00-80T-104. NATOPS Landing Signals Officer Manual.Schallhorn, SC, et al. Preliminary Results of PRK in Active Duty United

States Navy Personnel. Ophthalmology. 1996 Jan;103(1): 5-22.Schallhorn, Steve. Results of PRK in Naval Aviators. Presented at Fifth

International Congress on Epi-Lasik and Lasek and Advanced Surface Ablation, 2006.

Stanley, PF, et al. “Laser Refractive Surgery in the United States Navy. “ Current Opinion in Ophthalmology, 2008 Jul;19(4): 321-4.

United States Navy Aeromedical Reference and Waiver Guide.