I had the great opportunity recently to attend a lecture by Captain (ret.) Steven Schallhorn, MD who helped pioneer the Lasik surgery studies which lead to the approval of advanced Lasik techniques for US Military aviators and NASA Astronauts. His fascinating lecture delved into the history of Laser refractive surgery in the military and explained why certain Lasik procedures were deemed superior and acceptable for the intense visual demands of these personnel while other procedures were rejected.
Consider the demands for astronauts in the zero-G environment of outer space. For these people, even wearing glasses or contact lenses becomes extremely difficult. Glasses usually rely on the weight of gravity to stay in place but without it, the glasses will tend to float up and away from your face. Contact lenses will stay in place better, but taking care of them is extremely difficult in space. Since fluids will not fall downward with gravity, contact lens solution simply forms floating balls of liquid that float through the air. Of course you might ask why doesn’t NASA simply select only people who don’t need glasses? The paradox is that they wish to select the best-of-the-best of individuals for the very specialized tasks required of their astronauts and often those people do not have perfect vision.
With regard to Naval aviators in the past, many individuals who had hopes of becoming jet pilots were rejected because of their vision. It was only because of laser refractive surgery and studies conducted by Dr. Schallhorn that these individuals eventually had the opportunity to obtain these coveted positions. He talked specifically of the Retention and Accessioning studies which looked at PRK outcomes in pilots. These studies looked at a large number of pilots that were able to upgrade their qualifications and attrition rates among pilots in training. The positive outcomes for these pilots profoundly altered the Department of Defense’s vision standards for aviators allowing a wider pool of potential candidates.
Interestingly, these studies used the older PRK technology rather than Lasik. The major difference between PRK and Lasik is that Lasik uses technology to create a “flap” of surface tissue which allows for much faster recovery. The military actually required a 3 month minimum downtown for aviators having PRK. Dr. Schallhorn commented on the incredible cost in time, money, and training time lost when their pilots are out that long. As an example, fighter jet pilots are only able to maintain qualification for landing on an aircraft carrier at night if they have performed a landing within one week! Any longer than that and they are required to go through a requalification process. Despite all this, the data with older style Lasik involving conventional lasers and bladed instruments (microkeratomes) was never used because the data revealed that visual outcomes were not good enough. In particular, he stated that there is a slight loss of contrast and night vision with these older Lasik technologies which would be unacceptable for military pilots.
As time passed Lasik technology advanced as well. Eventually, Dr. Schallhorn and his associates took interest in studying the advanced wavefront guided Laser systems and Femtosecond Laser (FSL) technology which allowed for customized optical treatments and high precision blade-free Lasik. Studies comparing commonly used conventional bladed microkeratomes vs. the FSL technology demonstrated significantly faster visual recovery and potentially improved contrast vision. These are extremely critical outcomes for all military aviation personnel and also for civilians that wish to undergo vision correction surgery. He cited additional studies that showed that a combination of wavefront-guided Lasik and the FSL technology demonstrated a gain in night driving ability compared to conventional Lasik which showed a loss of night driving capability.
The combination of wavefront guided Lasers with FSL technology formed the basis of what would eventually be called the iLasik system which is made by Abbot Medical Optics. By 2007, the iLasik technology was approved by both the US military for their aviators as well as NASA for astronauts. Today, this advanced Lasik procedure is fast becoming the standard of care for Lasik in the US and offers the best chance for rapid recovery as well as potential visual improvement in areas of contrast vision and night driving tasks for all patients.