Evaluation of a myopic normative database for analysis of retinal nerve fiber layer thickness

IMPORTANCE Analysis of retinal nerve fiber layer (RNFL) abnormalities with optical coherence tomography in eyes with highmyopia has been complicated by high rates of false-positive errors. An understanding of whether the application of amyopic normative database can improve the specificity for detection of RNFL abnormalities in eyes with highmyopia is relevant. OBJECTIVE To evaluate the diagnostic performance of amyopic normative database for detection of RNFL abnormalities in eyes with highmyopia (spherical equivalent, -6.0 diopters [D] or less). DESIGN, SETTING, AND PARTICIPANTS In this cross-sectional study, 180 eyes with highmyopia (mean [SD] spherical equivalent, -8.0 [1.8] D) from 180 healthy individuals were included in themyopic normative database. Another 46 eyes with highmyopia from healthy individuals (mean [SD] spherical equivalent, -8.1 [1.8] D) and 74 eyes from patients with highmyopia and glaucoma (mean [SD] spherical equivalent, -8.3 [1.9] D) were included for evaluation of specificity and sensitivity. The 95th and 99th percentiles of the mean and clock-hour circumpapillary RNFL thicknesses and the individual superpixel thicknesses of the RNFL thickness map measured by spectral-domain optical coherence tomography were calculated from the 180 eyes with highmyopia. Participants were recruited from January 2, 2013, to December 30, 2015. The following 6 criteria of RNFL abnormalities were examined: (1) mean circumpapillary RNFL thickness below the lower 95th or (2) the lower 99th percentile; (3) one clock-hour or more for RNFL thickness below the lower 95th or (4) the lower 99th percentile; and (5) twenty contiguous superpixels or more of RNFL thickness in the RNFL thickness map below the lower 95th or (6) the lower 99th percentile. MAIN OUTCOMES AND MEASURES Specificities and sensitivities for detection of RNFL abnormalities. RESULTS Of the 46 healthy eyes and 74 eyes with glaucoma studied (from 39 men and 38 women), themyopic normative database showed a higher specificity (63.0%-100%) than did the built-in normative database of the optical coherence tomography instrument (8.7%-87.0%) for detection of RNFL abnormalities across all the criteria examined (differences in specificities between 13.0%[95%CI, 1.1%-24.9%; P = .01] and 54.3%[95%CI, 37.8%-70.9%; P < .001]) except for the criterion of mean RNFL thickness below the lower 99th percentile, in which both normative databases had the same specificities (100%) but themyopic normative database exhibited a higher sensitivity (71.6%vs 86.5%; difference in sensitivities, 14.9%[95%CI, 4.6%-25.1%; P = .002]). CONCLUSIONS AND RELEVANCE The application of amyopic normative database improved the specificity without compromising the sensitivity compared with the optical coherence tomography instrument's built-in normative database for detection of RNFL abnormalities in eyes with highmyopia. Inclusion ofmyopic normative databases should be considered in optical coherence tomography instruments.