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Web site created by Berney Design |
| Contrast sensitivity problems |
| Loss of contrast sensitivity (LOCS) occurs in almost all eyes after refractive surgery. Luckily, for most people the loss is minor and not noticeable, especially when both eyes are operated on at the same time and the point of reference is removed. The objective of glasses, contact lenses or refractive surgery is to allow the light entering the eye to focus uniformly on a single part of the retina. When this happens, the vision is crisp and clear. When there is a loss of contrast sensitivity the light entering the eye doesn't focus uniformly. Instead, some of the light scatters and the vision in that eye can appear darker then it used to be, washed out and/or foggy. Loss of contrast sensitivity can range from not noticeable to extremely annoying. At night, or when it's dark indoors, those with severe loss of contrast sensitivity can't see very well when compare to those with normal levels of contrast sensitivity. Often, they crave light. Sometimes they even have problems discerning distance and walking up and down stairs. During the daytime, vision can appear washed out or bland, as if someone turned down the color (think of a faded photo). It can sometimes be difficult to see and identify objects and driving can be a challenge. Loss of contrast sensitivity can occur for many reasons following refractive surgery, ranging from residual refractive error to astigmatism (regular or irregular) to haze on the corneal surface. Treatment of loss of contrast sensitivity is dependent upon the cause. Loss of contrast sensitivity due to residual refractive error can be reduced with glasses, contact lenses and sometimes additional refractive surgery. Additional surgery usually comes with a risk level similar to the original surgery. But these type cases are usually the mild ones and the residual refractive errors are usually more noticeable then the loss of contrast sensitivity. Loss of contrast sensitivity due to haze (especially haze formed after PRK) can often be treated, usually with success. It is important to notify the surgeon of the formation of haze immediately. Loss of contrast sensitivity due to a too small, or misplaced optical zone, or an irregular corneal surface after refractive surgery cannot currently be fixed with additional surgery, although technology continues to improve. |