Dry macular degeneration tends to be a slowly progressive disease, with subtle changes occurring over time. These changes may be noticed by the patient with gradually decreasing vision. Patients may also recognize these changes due to other symptoms, including gradually increasing distortion or gradual impairment of the ability to read.
In less common cases, sudden changes may occur. These sudden changes may be the culmination of a more gradual process, resulting in the involvement of a critical part of the macula. For instance, if dry macular degeneration began near, but not in, the center of the macula has occurred around the center of the macula and finally spreads to involve the center, the involvement of this critical area may cause immediate changes in vision.
Therefore, even though the overall process has progressed slowly, the involvement of this area will result in a sudden change, and this change may be dramatic. This is most often the case when geographic atrophy, an advanced form of dry macular degeneration, occurs and involves the center. It is impossible, however, for an ophthalmologist to predict with any degree of certainty the speed of progression or the rate of visual loss.
One eye may progress rapidly with loss of central vision while the other eye remains relatively stable with preservation of central vision. As described in Question 38, numerous researchers are studying investigational approaches to dry macular degeneration in order to prevent progression (either to more severe stages of dry disease or to wet disease). Many of these approaches are promising, and researchers are hopeful that breakthroughs will occur in the near future.