Name

Kératocône et aptitude au pilotage

Of the body senses, vision is the most important for safe flight. Keratoconus causes progressive blurring and distortion of vision, which threatens the career of a civilian or military aviator. The goal of this study was to evaluate the long-term outcomes of pilots with keratoconus.

To assess the impact of keratoconus on flying careers, we reviewed the records of all aviators presenting with keratoconus who have been examined in an Aeromedical Center over the past 10 years. 

Of the 17 aviators (10 civilians, 5 military) observed, 15 were still qualified to fly at their most recent examination. The remaining 2 aviators were permanently removed from flying duties because of visual dysfunction caused by keratoconus.

Ten civil pilots with ages between 25 and 49 years old presented with keratoconus in different stages (Stage 1, N=12 eyes ; Stage 2, N=6 ; Stage 3, N=2). Eight of these pilots began their career with a keratoconus. Corneal dystrophy was systematically diagnosed during the first expert visit. Using the Snellen scale, best corrected visual acuity (BCVA) was measured, all of them had equal or better than 20/32 (20/32, N=5 ; 20/25, N = 5; 20/20, N = 10). The average maximum keratometry was 47.57 +/-2.17 D, with a range of 41.9 to 52.1. Among these cases, 3 pilots had undergone treatment with crosslinking therapy. 

Five military pilots (3 fighter pilots) with ages between 24 and 42 years old presented with keratoconus (Stage 1, N=6 eyes ; Stage 2, N=4). All of them meeted the admission requirements to enter pilot training. The anterior and posterior corneal elevation maps were considered to be normal (not suspicious of keratoconus). Using the Snellen scale, best corrected visual acuity (BCVA) was measured in 10 eyes, all of them had equal or better than 20/25 (20/25, N = 5; 20/20, N = 5). The average maximum keratometry was 46.89 +/-2.54 D, with a range of 40.9 to 49.1. The assessment of visual quality using adouble pass aberrometry was performed for each pilot, the mean Objective Scatter Index (OSI) was (3.85 ± 0.98).

All of these 17 pilots have been given an aviation medical certificate by the French Civil Aviation Authority and/or the French Military Authority. Correction for defective distant vision (glasses or contact lenses) was imposed on 15 aviators. 

Keratoconus is a medical condition with aeromedical significance that should be detected by aviation medical examiners. Certification in aviation is possible in cases where there is stable disease with a stable response to vision correction and treatment. As the disease can potentially progress over a short period of time, certificate validity may be shortened accordingly, especially in affected younger applicants, whose disease could advance more aggressively. Distracting distortions, glare, flare, monocular diplopia, unstable refraction, and uncorrectable refractive error are symptoms that deserve special attention and put keratoconus as a cause for incapacitation during flight.

This study demonstrate that keratoconus is not always a disabling condition for  aviators. Most of them are able to continue their flying careers safely. Nevertheless, it has to be analyzed on a case-by-case basis.