Updated by Mike Rosco, MD on 3/13/23 at 6:19 PM
Decreased vision and double vision (aka diplopia) after retinal detachment surgery may occur, yet is not common. The perception of “double” is more common than actually seeing two of everything. There are several causes for really seeing two images following retinal detachment surgery.
Scleral Buckle May Cause Diplopia
A common method to fix a retinal detachment involves the use of a “scleral buckle.” This involves placing a belt, usually silicone rubber, on the outside of the eye and underneath the overlying eye muscles (see diagram below). Though the buckle assists in lowering the risk of a redetachment, it also will elongate your eye. The visual effect of this elongation is an increase in myopia (nearsightedness) and/or astigmatism.
The glasses prescription for the operative eye will change after scleral buckle surgery. Large prescription differences between the two eyes leads to a condition called anisometropia. Due to this large prescription imbalance, the brain cannot successfully fuse the two images into one size.
Why? Inherent to large changes in prescription is a change in the actual size of the image that we see. Thus, with a large prescription disparity between the eyes, the brain actually sees two different sized images.
This is probably the most common cause of “double vision” after retinal detachment surgery.
Of note, at times, manipulation of the eye muscles can cause true double vision. The muscles may get injured or impaired such that the eye does not move in coordinated fashion with the other eye. Diplopia can occur from this muscle imbalance
Cataracts Can Cause Diplopia
Gas is commonly used to repair a retinal detachment. A common side effect of intraocular gas is the hastened formation of a cataract. This, too, can change the prescription of the eye dramatically. “Double vision” can result from cataract formation by causing a strong shift in the prescription (the way the light is focused as it enters the eye).
What Does This Mean? There are many causes of decreased vision following retinal detachment surgery and many are described as “double vision.” However, true double vision, where the eyes are misaligned after surgery, is quite uncommon after retinal detachment surgery. Many cases of double vision are actually caused by changes in the prescription, either due to physical changes of the eye from the scleral buckle or due to advancing cataract.
Happily, most cases can be fixed. If the retina is functioning well enough for the double vision to be “seen,” then it is likely that corrective measures can be taken.
For anisometropia (double vision due to a large difference in prescriptions between eyes), a contact lens can be fitted to assist with making the eye prescriptions more similar. Cataract extraction with implantation of a new intraocular lens is an option if the eye’s natural lens changes after retinal detachment surgery. Finally, for cases of “true” double vision due to eye misalignment, eye muscle surgery can help position the eyes into alignment once more.
