Special Report
Challenges of the Diabetic Cornea
Diabetic neuropathy underlies a range of issues that impact vision, comfort and surgical recovery.
By David R. Hardten, MD
In any stressful situation for the eye, such as surgery or concomitant dry eye and blepharitis, diabetic patients have a much weaker than normal ability to maintain a healthy ocular surface. As the disease damages nerve endings, diabetic neuropathy causes the ocular surface to lose sensitivity. Patients have impaired wound healing, greater chance of corneal lesions and sometimes develop diabetic keratopathy. They're more prone to issues with dry eye or blepharitis, and these problems are more symptomatic and bothersome. Because ocular challenges such as dry eye or surgery have a greater impact on the diabetic cornea, we need to take greater steps for treatment.
Tailored Treatment
The diabetic eye disease case I see most commonly in my referral cornea practice is the patient who has had vitrectomy for hemorrhage and has diabetic keratopathy afterward, caused by the trauma to the conjunctiva by surgery and medication. In a retina practice, surgeons might see the same diabetic keratopathy in patients who have diabetic retinopathy. The key is to watch for early signs of diabetic keratopathy and treat it aggressively.
Our goal is to prevent permanent, long-term scarring as a result of diabetic keratopathy. We must reduce sub-epithelial inflammation and get the epithelium healthy and protected with a combination of non-preserved lubricant, topical cyclosporine and oral doxycycline. Some cases require less common therapies such as serum tears, which provide helpful factors. Severe cases may call for tarsorrhaphy to cover up the eye or amniotic membrane grafting to promote better healing.
Generally, we manage dry eye and blepharitis more aggressively in diabetic patients, using artificial tears and cyclosporine to maintain a healthy epithelium. It's essential to avoid toxic medications and preservatives when possible, and use NSAIDs judiciously after vitrectomy or cataract surgery because these drugs are hard on the ocular surface.
Surgical Considerations
Before we perform cataract surgery on a diabetic patient, we need to make sure the ocular surface is as healthy and calm as possible. Perioperatively, we're aggressive about identifying issues such as dry eye or blepharitis and treating with hygiene, tears, cyclosporine and topical azithromycin.
After cataract surgery, because risk of cystoid macular edema is high, I use NSAIDs for 2 months. We must use an NSAID, which means that keeping the ocular surface healthy is a very fine balance. If any epithelial problem arises, we try to identify it quickly. I usually increase lubricants and may reduce the NSAID. But even with aggressive management, neurotrophic ulcers can still occur, usually requiring an amniotic membrane transplant.
Other surgeries, such as corneal transplant, are a dramatic insult to the corneal nerves. I almost always do a tarsorrhaphy to keep epithelium stable on the transplant in the first months, when there is extra risk of keratopathy and dryness.
Complications of Noncompliance
Patients with types 1 or 2 diabetes, old or young, compliant or noncompliant, can have disease-related problems with their corneas. However, we most frequently see older patients with concomitant issues, and most patients with significant problems are noncompliant with treatment for diabetes. It can serve as a breakthrough for these patients. They're having vision and comfort problems, as well as possibly dramatic complications. But if we can identify the problem, explain it to the patient in terms he can understand, then notify his doctor, we can all work together to control the disease and restore and maintain a healthy epithelium and an environment that discourages complications.
David R. Hardten, MD, directs the research department and is the fellowship director at Minnesota Eye Consultants. He is an adjunct associate professor of ophthalmology at the University of Minnesota. |