Challenges in the clinical measurement of ocular surface disease in glaucoma patients

Ocular surface disease (OSD) is common among glaucoma patients. Clinical assessment of OSD can be challenging. This review focuses on some of the limitations relating to both subjective and objective measures of OSD, including dry eye. A survey of the literature was conducted to identify the caveats associated with different methods of assessing OSD. The effect of preservatives on the ocular surface, with respect to glaucoma patients in particular, was also reviewed. Objective methods for assessing ocular surface health and disease include the Schirmer test, tear break-up time, fluorescein turnover, corneal and conjunctival staining, tear osmolarity, and vital dyes. These measures all have limitations in terms of their ability to grade the severity of OSD. Previous studies using the OSD Index showed a mild-to-moderate correlation to dry eye disease severity. Other scoring systems for dry eye have shown a relationship to patient symptom scores or quality of life. Due to the challenges clinicians face concerning both subjective and objective ocular surface health assessments, discerning clinical improvement in ocular surface disease can be a challenge. Further research is needed in order to optimize existing clinical methods and/or identify alternative techniques for assessing OSD in the glaucoma population.