Sanjukta Jana, B.Optom
Student, NSHM Knowledge Campus – Kolkata, India
Imagine you are in an aeroplane floating high in the sky amongst clouds and suddenly the pilot experiences blurry vision and Boom! The aeroplane crashed by a skyrocket. To avoid aero-medical risk, vision testing is done before the recruitment of pilots for management purposes. Eyesight is a ball game. There are some of the intimidating remarks for a pilot’s sight, which are discussed below.
Dry Eyes:
Dry eyes occur when there is inadequate tear volume or function resulting in an unstable tear film. It is the most ocular surface disease in aerospace drivers. Compact cockpits at high atmospheric conditions accelerate the evaporation of eye problems. The most usual symptoms include grittiness and a burning sensation.
The underlying causative processes of dry eye are generally irreversible hence management is structured around the prevention of surface damage. Instillation aids for eye drops should be advocated. Eyelid therapy can be performed by applying warm compresses. In the case of contact lens prescriptions, low water content HEMA lenses may be fitted in moderately dry eyes. (1)
Figure 1: Showing cockpit of an A380. Most Airbus cockpits have a glass cockpit cabin resulting in high atmospheric conditions causing dry eyes.
[Pic courtesy – https://web.archive.org/web/20101107042658/http://samchuiphotos.com/A380Sydney/A380_Australia_visit_November_2005.html]
Space Myopia:
Space myopia is experienced when the individual has no stimulation for distance fixation. The eyes tend to choose a near fixation plane which can be variable. It is particularly troublesome to aviators when flying in clouds or fog at night. The crystalline lens focuses light from an object on the retina. Space myopia occurs when a person’s eye is exposed to a bright empty field or a completely dark field where there is no object to stimulate the lens to focus light on the retina. Consequently, the lens gradually shifts to a resting phase. In simple terms, the lens is focused on the intermediate point. (2)
Space myopia can hinder normal visual detection of air traffic. Increasing peripheral awareness and practice of focusing on various objects might be practised for the betterment of this condition. (2) The degree of myopia due to this condition is never more than 0.75-1.5D. (3)
Glare Problems:
While flying at high altitudes pilots may be exposed to darkened skies above and bright reflected light rays from clouds beneath. The contours of the human face protect the eyes from bright light coming from above but not from below. (4) As a result, glare problems rise. In many instances inadequately maintained glass panes or screen panes enhance glare issues. To prevent any difficulties caused due to glare use of appropriate sunglasses may be remedial. The use of larger lenses and wrap-around frame glasses prevent sun rays from entering peripherally affecting vision. (4)
Figure 2: Pilot wearing sunglasses to overcome glare problems faced during flight.
[Pic Courtesy : https://www.flyingmag.com/guides/best-pilot-sunglasses/]
Eye Strain:
To see and avoid air traffic a pilot’s eye may require changing focus from heads up looking at the glass to heads down looking at the computer screen searching for traffic. (5) The extremely prolonged bright light leads to pupillary constriction. All these phenomena result in the overuse of ciliary muscles resulting in ocular fatigue. This situation can be managed using proper sunglasses as per the requirement needs of the aviator.
Wishing you a safe journey. Contact an optometrist for proper treatment.
References:
- Kanski, J., and B. Bowling. “Kanski clinical ophthalmology (8th Ed). China.” 2016.
- Empty field myopia. SKYbrary Aviation Safety. (n.d.). Retrieved on March 16, 2023, from https://www.skybrary.aero/articles/empty-field-myopia#:~:text=Empty%20field%20myopia%20(Empty%20space,of%20a%20few%20metres%20ahead
- Khurana AK, Khurana AK, Khurana B. Theory and practice of optics and refraction (4th ed.). Elsevier India; 2014.
- Knezevic, J. “Glare as a Mechanism of the Motion of an Aircraft Through the MIRCE Functionability Field.” (2019).
- White, J. (2020, March 7). Eye strain and vision fatigue in the Cockpit. Aviator Sunglasses. [Retrieved on March 16, 2023, from https://aviator-sunglasses.net/blogs/sunglasses/eye-strain-and-vision-fatigue-in-the-cockpit]
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