In some cases, the vitreous gel can peel the retina away from the back of the eye, resulting in a macular hole or retinal tear. This can progress into a retinal detachment if left untreated. Injury or trauma Very occasionally, an injury to the eye or trauma can result in a retinal detachment.
Breathing at higher altitudes might be especially difficult if you have COPD as well as another condition, such as high blood pressure, heart disease, or diabetes. Being exposed to high-altitude conditions for more than several days can also affect the heart and kidneys.
Most doctors do not mind pregnant women flying during their first trimester; it is actually during the third trimester that pregnant women are told not to fly as it could trigger labor. Flying during the first trimester may be unadvisable if it involves too much stress which could harm the baby and the mother. It is also unadvisable if the woman has had a history of miscarriages or ill health. Flying may cause air sickness which pregnant women are particularly vulnerable to.