Purpose: To quantify the specificity and sensitivity of RTVue-100, Optovue parameters at determining the presence of a relative afferent pupillary defect (RAPD) by coupling their values with the instrument normative data base (NDB) and the presence of a RAPD. To generate the distribution for the focal loss volume (FLV) percentage, by coupling its value to the instrument NDB and presence of a RAPD. Methods: Forty one subjects with a RAPD and glaucomatous or non-glaucomatous optic neuropathy participated. A neutral density filter bar was used to estimate the RAPD. The specificity and sensitivity of all parameters was analyzed using Fisher’s Exact test. The distribution of the FLV percentage was analyzed using a one-way ANOVA with a Tukey HSD post hoc test. Results: The FLV percentage was more sensitive (100%) but less specific (64%) than other parameters. Eyes of subjects with FLV percentage and NDB p-values < 1% were 33.8 times more likely to have a RAPD [95% CI: 7.2, 325.1]. Confidence limits for the distribution of FLV percentage were; 6.32/10.59 um for eyes with NDB p-values < 1% with a RAPD; 2.04/7.56 um for eyes with NDB p-values >1% with a RAPD and 1.08/6.22 um for eyes with NDB p-values > 1% without a RAPD. Conclusion: Compared to other RTVue-100, Optovue parameters the FLV percentage is more sensitive at determining eyes with a RAPD and may significantly categorize optic neuropathy according to severity.