A number of people inquire about the possible ophthalmologic consequences of doing inverted postures. First, it is wise to have a careful examination of the eyes by an ophthalmologist (i.e., an M.D. or D.O. eye physician and surgeon) prior to beginning any extended inversion postures. Such an examination might discover asymptomatic eye conditions that inverted postures could adversely affect, and would prevent further damage. The principal concerns are glaucoma, retinal detachment and macular degeneration.
The common variety of glaucoma (open-angle) is manifested by a gradual, progressive loss of visual fibers from the optic nerve, the nerve that carries visual information from the eye to the brain. It is almost always completely asymptomatic until considerable damage has been done. In most cases there is an intermittent or constant elevation of the fluid pressure inside the eye (intraocular pressure or IOP) and current treatments aim at lowering this pressure to slow or stop the damage. The diagnosis may be made in the asymptomatic individual in several ways, including measurements of the IOP, careful examination of the optic nerve and surrounding layer of nerve fibers as they enter the nerve, and accurate testing of the visual fields (side or peripheral vision), which is usually affected before the central portion of vision. Other less common forms of glaucoma, including narrow-angle glaucoma, are often accompanied of symptoms of pain, redness and visual loss and are readily diagnosed by the ophthalmologist.
WARNING: Inverted postures will greatly increase the IOP and accelerate the damage and are absolutely contraindicated for any form of glaucoma at any stage. It has been written elsewhere that one need only abstain from inversions in the case of narrow-angle (or angle-closure) glaucoma. This view is dangerous and false.
The retina is the thin inner membrane of the back portion of the eye. It functions like the film of a camera, receiving the image of the outside world focused upon it by the optics of the eye. It converts this image into nerve impulses, which are then transmitted via the optic nerve to the brain. In the common form of retinal detachment, a hole or tear, usually in the peripheral retina, develops due to degeneration (often associated with high nearsightedness) or injury. Fluid passes through this break and separates the retina from its supporting and nourishing layers. Although these events are usually accompanied symptoms including flashes, floaters and/or a noticeable defect in the peripheral vision, some cases are asymptomatic.
WARNING: Inverted postures would likely spread the detachment and significantly aggravate the problem. A careful ophthalmologic examination might detect conditions predisposing an individual to this disease and lead to prophylactic treatment. Inverted postures are not necessarily contraindicated in persons with treated retinal detachments or predispositions, but should be performed only with the consent of the ophthalmologist. Careful follow-up examinations are usually required.
The macula is the central area of the retina and receives the image of the object that we are looking directly at. Macular vision is the sharpest area of our vision and the only area that can distinguish colors. Unkindly, the macula is also the portion of the retina most susceptible to a very common condition called age-related macular degeneration (AMD). In the more severe form of AMD (called the neovascular or “wet” form), abnormal new blood vessels develop under the macula, often causing bleeding into the macula and separation of retinal layers.
WARNING: Inversions may aggravate this problem and must be avoided. In the less severe and more common atrophic or “dry” form of AMD, inversions are usually permissible with the consent of the ophthalmologist. There are other forms of macular degeneration associated with diabetes, high nearsightedness, certain infections and other conditions. The ophthalmologist should be consulted for individualized advice in such cases.
Inverted postures accompanied by straining or breath-holding (knows as Valsalva maneuvers) can lead to bleeding inside even a perfectly healthy eye and should always be avoided.