Intraocular gas will expand when cabin pressure drops while flying at a high altitude. The subsequent increase in intraocular pressure can cause clinical symptoms. Ischemia may occur if there is prolonged occlusion of the central retinal artery.
Perfluorocarbon or other gases may be injected into the eye after vitrectomy or repair of retinal detachment. A gas that is slowly absorbed may be present for weeks or even months.
Critical volume of gas: 10% of eye volume (0.6 mL). The eye can compensate for the expansion of smaller volumes.
Risk factors:
(1) elevated intra-ocular pressure from other causes (glaucoma, drugs, etc.)
(2) larger volume of intra-ocular gas
(3) lower cabin pressure
An acclimatized person departing from a city at a high altitude will tolerate a given altitude better than someone departing from a lower altitude since the intra-ocular pressure will have adjusted to a lower atmospheric pressure.
Clinical manifestations:
(1) severe ocular pain
(2) drop in visual acuity (dimming of vision)
Recommendations:
(1) Inform the pilot prior to take-off of the problem
(2) If symptoms develop during a flight, request descent to a lower altitude (decrease of 2,000 or more feet)
To read more or access our algorithms and calculators, please log in or register.
