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The majority of all research in the field of contact lenses has taken place in a normal, ground-level environment. The purpose of this study was to determine if any changes occurred in wearing hydrophilic soft lenses under conditions of low atmospheric pressures. The effects on visual acuity, refraction, keratometry, and biomicroscopy were investigated with eight naval volunteers while wearing soft contact lenses at simulated altitudes up to 30,000 ft (9144 m) in an aviation hypobaric chamber. The results indicated that the low atmospheric pressure at high atitude in itself did not affect the fit of soft contact lenses.

The increasing use of hydrophilic (soft) lenses in the United States hs prompted interest in the clinical investigation of these lenses under various wearing conditions. Any factor causing lens dehydration during wear may affect lens performance and ultimately cause eye discomfort. The purpose of this study was to evaluate the environmental conditions in the aircraft cabin and to observe any changes in the fit of the hydrophilic lenses that might occur during flight. A "laboratory" for testing was set up aboard a World Airways DC-10 on a scheduled round trip between Oakland, California and Honolulu, Hawaii. A keratometer was used to assess lens fit of seven subjects who were wearing hydrophilic lenses. The efficacy of using a soft lens hydrating solution on the fit of the lens was evaluated, but will also be evaluated in a future paper. Atmospheric pressure, humidity, and temperature measurements were recorded throughout the inflight study. The results showed that a decline in cabin humidity from at least 47% to 11% occurred within 30 min of takeoff. Although previous reports have indicated that there are a number of environmental factors in the aircraft that contribute to eye discomfort for lens wearers, this study indicates that low cabin humidity is possibly the most significant factor.

Flight attendants frequently use ophthalmic solutions (eye-drops) to relieve their eye discomfort while working in the aircraft. The purpose of this paper is to present some insight concerning the use of ophthalmic solutions by flight attendants. This paper follows Part I, a survey that evaluated some of the environmental conditions in the aircraft that influenced eye comfort. A questionnaire was developed in conjunction with the Air Safety Department of the Association of Flight Attendants. The common eye problem characterized by conjunctival redness and eye irritation occurred with 95% of the 774 respondents. Furthermore, 60% of these respondents indicated that they have used eyedrops while in flight. The majority of the respondents were using an ocular decongestant; however, this author suggests that the use of artificial tears would be more effective in relieving eye discomfort in the aircraft.

Extensive research in aviation medicine has been devoted to various aspects of vision, but there has been little attention to the eye problems of flight attendants. Flight attendants, especially contact lens wearers, have complained about eye discomfort in aircraft. The purpose of this study was to evaluate some of the conditions in aircraft that might influence their eye comfort. A questionnaire on eye comfort was developed in conjunction with the Air Safety Department of the Association of Flight Attendants and distributed through its Flightlog magazine. Of the 774 respondents, 95% reported some eye discomfort in aircraft. It is significant that both those who did and who did wear contact lenses reported similar eye problems. The most common eye problems reported were conjunctival redness and dried eyes. Smoking was indicated by the respondents to be the most noticeable factor causing eye symptoms. Aircraft cabin conditions are discussed, including relative humidity, atmospheric oxygen, and ozone concentration. Since air passengers are exposed to the same aircraft conditions as the attendants, they probably would manifest similar eye problems.