A small opening causing a blind spot or blurred vision
The macula is the area of the retina that is responsible for sharp central vision. It is used for reading, watching television, and driving, among other visual tasks. In some eyes, the vitreous or gel that fills the back part of the eye pulls in an abnormal fashion on the macula and eventually makes a defect in it called a "macular hole". A macular hole often develops over several months. Injury or long-term swelling can also cause a hole in the macula.
Most people who develop a macular hole are over 60 years of age. In addition to aging, risk factors for the development of macular holes include trauma to the eye, high myopia (nearsightedness), retinal detachment, macular pucker, and long standing macular edema.
Macular holes often begin gradually. In the early stage of a macular hole, people may first notice only a slight distortion of what should be straight lines in the center of the vision of that eye. (This can also be a symptom of other macular diseases). After a period of distortion a small blank spot appears in the absolute center of vision and enlarges over the next month or so. Ultimately the defect in the retina is approximately one-half millimeter (about 1/50 of an inch) and is sufficient to blot out an entire word in newsprint. Vision around the central absolute blank spot is also disturbed because fluid from the vitreous cavity goes through the hole and collects under the retina at its edges. At this point the vision is typically 20/200, the level required for "legal blindness" to be declared for an eye. Once a macular hole has reached this stage the vision typically remains at this level with no further worsening. Although macular hole is a different condition from age-related macular degeneration, symptoms are similar. An eye doctor can properly diagnose the correct condition.
Sometimes an 'impending' macular hole is diagnosed before a full thickness retinal defect develops. Since about 50% of these eyes will spontaneously repair themselves, observation rather than surgery is recommended in those cases. Should a full thickness hole develop, vitrectomy surgery is performed. During this procedure, vitreous gel and scar tissue that keeps the hole open are removed, and then the eye is filled with an air bubble which pushes up against the macula and helps close the hole (see Macular Hole Surgery). The air bubble will eventually dissolve, but the patient must maintain a face down position for about one week to maintain the air bubble’s pressure on the macula. Treatment success usually depends on how well the position is maintained. With current techniques, we are able to close about 90 percent of macular holes. Most of these experience a substantial improvement in vision. Many eyes achieve vision of 20/60 to 20/80 from the original 20/200. A few have a visual return to nearly 20/20. Usually patients describe a persistent but much smaller central defect with no distortion. The closure rates and visual results are best if the operation is performed within about six months of the onset of symptoms. At the other extreme, macular holes that have been present for over two years, especially due to trauma, have a much lower closure rate and minimal , if any, visual improvement.