A potential primary endpoint for clinical trials in glaucoma neuroprotection

The purpose of this retrospective, longitudinal study is to evaluate the relationship between MD slope from visual field tests collected over a short period of time (2 years) and the current United States' Food and Drug Administration (FDA) recommended endpoints for visual field outcomes. If this correlation is strong and highly predictive, clinical trials employing MD slopes as primary endpoints could be employed in neuroprotection clinical trials with shorter duration and help expedite the development of novel IOP-independent therapies. Visual field tests of patients with or suspected glaucoma were selected from an academic institution and evaluated based on two functional progression endpoints: (A) five or more locations worsening by at least 7 dB, and (B) at least five test locations based upon the GCP algorithm. A total of 271 (57.6%) and 278 (59.1%) eyes reached Endpoints A and B, respectively during the follow up period. The median (IQR) MD slope of eyes reaching vs. not reaching Endpoint A and B were -1.19 (-2.00 to -0.41) vs. 0.36 (0.00 to 1.00) dB/year and -1.16 (-1.98 to -0.40) vs. 0.41 (0.02 to 1.03) dB/year, respectively (P < 0.001). It was found that eyes experiencing rapid 24-2 visual field MD slopes over a 2-year period were on average tenfold more likely to reach one of the FDA accepted endpoints during or soon after that period.