Good vision and healthy eyes – including good depth perception – are extremely important in aviation. This has been recognized since the beginning of manned flight, and our earliest medical standards emphasized this factor by "looking" for perfect vision in would-be pilots.
Both military and commercial aviation interests rejected applicants for pilot positions if these applicants required visual correction or had more than very minimal refractive error. Only more recently has there been some relaxation of these requirements, at least in the civilian sector.
The Federal Aviation Administration's (FAA's) medical standards were changed in September 1996 to permit airman medical certification, regardless of uncorrected distance visual acuity, if each eye is corrected to 20/20 (first- and second-class certification) or 20/40 (third-class certification). Certification is contingent on the person wearing the required corrected lenses while exercising the privileges of an airman certificate. The changes were based, however, on many years of certification experience that demonstrated no excess risk with the use of proper visual correction.
Not everyone has agreed with this change or with FAA's adoption of a less stringent, but job related color vision standard. We believe, however, that the current standards are appropriate, but recognize that vigilance regarding accident experience is necessary.
The Office of Aviation Medicine, under the auspices of the International Civil Aviation Organization, will participate this summer in a multinational working group that will study vision issues. Included in the study will be consideration of the various methodologies of refractive surgery, such as photorefractive keratectomy (PRK).
The use of these procedures among pilots and air traffic control specialists appears to be rapidly increasing, even though there is concern without the aeromedical community about the suitability of the procedures in aviation and about potentially adverse outcomes. While our experience so far has been good, we look forward to gaining a more comprehensive assessment.
Pilot "Monovision" Cited
On Tuesday, June 17, the National Transportation Safety Board (NTSB) met to consider the Delta Air Lines MD-88 accident that occurred at New York's LaGuardia Airport on October 19, 1996.
Three passengers (of 58 passengers and 5 crewmembers) received minor injuries during the accident in which the aircraft was substantially damaged on landing short of the runway.
The probable cause of the accident was determined to be an undershoot on landing caused by the captain's use of a monovision contact lens, which, they found, had degraded his depth perception. The Board concluded that the pilot's ability to perceive distance and attitude was further affected by visual illusions caused by the light conditions, irregular spacing of runway lights, rain and fog. Contributing to the accident was the lack of instantaneous vertical speed instrumentation available to the first officer.
The NTSB further found that there is incomplete guidance available to Aviation Medical Examiners, optometrists and pilots about the effects and limitations of monovision contact lenses when flying.
Among other recommendations, the NTSB advised that the FAA Civil Aeromedical Institute should publish information on the hazards of monovision contact lenses and that the Application for Airman Medical Certification (FAA Form 8500-8) be revised to elicit contact lens usage information from applicants. The Office of Aviation Medicine is considering these recommendations.
Secretary of Transportation
Barry Valentine (Acting)
Federal Air Surgeon
Jon L. Jordan, MD, JD
Michael E. Wayda
The Federal Air Surgeon's Medical Bulletin is published quarterly for Aviation Medical Examiners and others interested in aviation safety and aviation medicine. The Bulletin is prepared by the FAA's Civil Aeromedical Institute, with policy guidance and support from the Office of Aviation Medicine. AMEs and other authors should submit articles and photos for publication in the Bulletin directly to:
FAA Civil Aeromedical Institute, AAM-400
P.O. Box 25082
Oklahoma City, OK 73125