EyeWorld India December 2021 Issue

CORNEA EWAP DECEMBER 2021 31 stromal haze but who don’t have persistent epithelial defect,” Dr. Holland said. “Our Stage 2 is where a lot of patients get diagnosed with dry eye when we want physicians thinking about NK.” Dr. Holland said the hope is that this will provide more understanding that there are many stages. “Unfortunately, people don’t think about NK until it’s a round corneal ulcer and scarring, and that’s when the light bulb goes off,” he said. Clinical diagnosis of NK When doing a workup for the clinical diagnosis of NK, Asim Ali, MD, said he’s trying to figure out the etiology. For example, if you know there’s a clear history of herpes, that makes it more straightforward, he said. If it’s completely out of the blue, you might have to do an MRI to rule out structural problems in the brain or tumors. The workup will depend on how the patient presents and if you can distinguish between a cause that’s in the eye itself. In making a clinical diagnosis, Dr. Holland said the number one thing is to have a differential diagnosis. Dr. Holland also stressed that it’s not necessary to have a quantified professional aesthesiometer. “A lot of people used to use the tip of a cotton swab but even easier is the edge of tissue paper or piece of dental floss,” he said, adding that corneal sensation should be in the workup. Dr. Beckman said that when making a clinical diagnosis it’s important to do staining to establish that the patient has keratitis in general. Then he will check sensation if they have staining or a defect and if he is suspicious of NK. “If they have decreased sensation, I typically treat as NK,” Dr. Beckman said. “I understand that many patients may have decreased sensation and coexisting epithelial disease, but the neurotrophic cornea may not have caused the keratitis.” He added that it may be dry eye, medication toxicity, or something else. “I treat with traditional methods first, but if they have these findings and do not respond to conventional treatment, I treat as NK,” Dr. Beckman said. Systemic diseases associated with NK and NK from herpes Dr. Beckman has found that the two most common systemic diseases associated with NK are diabetes and MS. NK can also be associated with herpes. Dr. Beckman said he hasn’t found a big difference between herpes simplex and herpes zoster in severity. “The one curveball is that with herpes simplex, we need to determine if there is active viral keratitis requiring antiviral therapy rather than just treatment for NK,” he said. “I prefer oral antivirals, particularly because they don’t have the toxicity that topical therapy does.” Dr. Holland said there are a number of conditions that can be associated with NK. In addition to herpes simplex and herpes zoster, he said that any severe infection on the cornea or severe injuries, like chemical burns, can lead to NK. Other factors like LSCD and chronic contact lens wear can also be associated. Dr. Holland added that you can see NK from ocular surgeries, such as PK or DALK, refractive corneal surgery, or any procedure that removes epithelium. Medications can also be associated with NK. Dr. Holland said there are some congenital causes as well, though these are generally rare. Treatments There are a number of treatments for NK that physicians can employ at various stages and depending on the individual patient. According to Dr. Holland, it’s a “step ladder approach” based on the severity. In the early steps, it’s important to add preservative- free lubrication and remove any toxic topical medications, which can cause dryness on the surface, Dr. Holland said. If there is ocular surface disease, it should be treated with preservative-free drops, ointments, omega-3s, etc. Different types of contact lenses can also be used. Dr. Holland will use bandage contact lenses as an early treatment. “If there’s confluent punctate staining and I’m worried about scarring or ulceration, I want to be aggressive with an early bandage contact lens,” he said. Dr. Beckman also said he uses a bandage contact lens to treat a persistent defect. “Initially, for NK, I treat these patients the same as non-neurotrophic corneas with persistent defect, and bandage contact lenses are used very early,” he said. “I may add amniotic membrane to those as well.” Dr. Beckman added that the main risk with a contact lens is infection, so antibiotics are typically used. “Of course, the more drops that are used, the greater the risk of toxicity compromising healing, so it must be a balance,” he said. A scleral contact lens may be helpful, and Dr. Beckman said these can be particularly useful in cases of non-healing defects and dry eye, though they can be expensive. “Some vision insurances will cover scleral lenses for certain diagnoses, but NK may not be covered,” he said. “If these are attainable, they can work very well.”