In the short term after your operation, glaucoma surgery temporarily disrupts your vision. It is important to understand that permanent vision can be reduced, or even, in very rare instances, totally lost as a result of any of these glaucoma operations; however, vision loss is not a common side effect. Therefore, it is more likely that surgery will benefit your vision in the long run.
With any of these operations, complications can occur even with the best surgical techniques. Uncommon or rare complications include bleeding inside the eye, infection, and fluid pockets behind the retina due to very low eye pressures. Bleeding inside the eye can be a very serious complication, so you should talk with your ophthalmologist if you are on blood thinners and follow his/her instructions about continuing or discontinuing the medication prior to surgery.
Eye doctors give antibiotics before, during, and after the surgery, as well as maintain meticulous sterile techniques to try and avoid any infection. However, on very rare occasions, infection inside the eye may occur, which can be very serious and may threaten vision. These infections can occur weeks, months, or even years after the surgery. Therefore, if you have early signs of infection such as redness, pain, or excessive tearing, you should see your ophthalmologist immediately in order to treat infection before it becomes serious. Caught early, most infections can be adequately treated with antibiotic drops.
Low Eye Pressure
Sometimes, the surgery can lead to eye pressures that are too low, also called hypotony. This is more common soon after the surgery. With hypotony, fluid may collect behind the retina (choroidal detachment), which can cause a shadow in your peripheral or side vision. Usually this is temporary as the pressure returns to the levels that were intended. Sometimes, however, hypotony persists and surgery must be performed in order to fix this problem.
More common than causing eye pressure that is too low, these glaucoma surgeries may fail over time due to the natural healing or scarring tendencies of the eye, resulting in eye pressures that are higher than intended. Sometimes, the scarring is so intense that the operation may fail to achieve a lowered pressure and you may need to restart your glaucoma medications or undergo repeat surgery.
Cataract formation most likely will be accelerated by glaucoma surgery, but luckily cataracts are fairly easy to fix surgically. Sometimes glaucoma surgeries are combined with cataract surgery if your ophthalmologist feels that the cataracts are having a moderate to significant impact on your vision.
Safer Procedures on the Horizon
MIGS (minimally invasive glaucoma surgery) are a group of newer procedures that are usually combined with cataract surgery to lower eye pressure to the mid-teens range. In most instances, the safety profile of these procedures is higher than the more traditional glaucoma surgeries described above. However, this enhanced safety profile is counterbalanced by a more modest eye pressure reduction. Therefore, these procedures are usually combined with cataract surgery for patients with early- to moderate-stage glaucoma. For patients with advanced glaucoma, the MIGS procedures are less likely to achieve the low eye pressures needed.
While it is important to understand the risks discussed above, many of which are rare, it is also important to recognize that the vast majority of glaucoma surgeries are successful at slowing the progression of glaucoma and achieving the intended eye pressure.