Ocular Surface Disease in Patients with Glaucoma
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Ocular surface disease
Ocular surface disease represents a spectrum of disorders that affect the surface of the eyes. Dry eye syndrome is one of the most common ocular surface diseases, with incidence ranging from 5.7% to 21.6%. Symptoms of dry eye and ocular surface disease include sensation of dryness, redness, tearing, irritation, burning, foreign body sensation, light sensitivity and intermittent blurred vision. Questionnaires and surveys such as the Ocular Surface Disease Index (OSDI) and Symptom Assessment iN Dry Eye (SANDE) represent methods of characterizing associated symptoms in a systematic manner.
With a prevalence of 3.54%, glaucoma is one of the leading causes of blindness worldwide. Symptoms from primary open-angle glaucoma (POAG) generally only arrive when the disease is well advanced portending the importance of screening eye exams and diagnosis in early phases of the disease. The typical signs are related to secondary effects of the optic neuropathy on anatomy of the eye and functional performance with visual field testing. However, given that the most common first line of therapy of glaucoma is topical therapy, development of symptoms from the treatment itself is possibly more prevalent and described below.
Ocular surface disease in patients with glaucoma
Both ocular surface disease and glaucoma are more common in older, and first-line therapy for these disease entities are topical medications. They are both spectrum of disease and severity but when coexistent can compound each other. This interaction is further complicated by treatments for each condition which can interact and yield counterproductive effects (Figure 1).
Glaucoma treatment may cause chronic inflammation or aggravate a concomitant ocular surface disease. Clinical trials of drugs most often test only one specific medication and preservative at a time, and often only for a short period of time. They do not test multiple or all classes of medications simultaneously for a prolonged period of time. However, in clinical practice patients with glaucoma are typically treated for many years or even decades. Patients may also have preexisting ocular surface disease, dry eye, meibomian gland dysfunction, or chronic allergy and are very frequently treated with more than one topical glaucoma medication. Some ocular surface issues can wax and wane while overall possibly worsening as we get older. It is for these reasons that clinical practice does not always fit into the safety profile of typical clinical trials for medications. There is still no standardized definition nor classification or assessment of glaucoma therapy related ocular surface disease. Hollo et al. defined glaucoma therapy-related ocular surface disease well as, “imbalance of the ocular surface homeostasis caused by the toxic effect of chronic topical medication, which leads to tear film instability, epithelial damage, and inflammation.”
This article will review the manifestations of ocular surface disease in glaucoma patients and review medical and surgical treatments currently available and potential algorithm of management.