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Editors Selection IGR 16-3
Anatomical structures: RNFL and disc hemorrhage
Comment by Gustavo de Moraes on:
58890 Changes in retinal nerve fiber layer thickness after optic disc hemorrhage in glaucomatous eyes, Hwang YH; Kim YY; Kim HK et al., Journal of Glaucoma, 2014; 23: 547-552
In this retrospective longitudinal study, Hwang et al. investigated changes in one retinal nerve fiber layer thickness (RNFLT) measured with spectral-domain optical coherence tomography (sdOCT) after optic disc hemorrhage (DH) in glaucomatous eyes. They included patients with a single or recurrent DH in only one eye and selected a control group of glaucomatous eyes without DH, but who underwent three sdOCT scans with a one-year interval. Event-based significant RNFLT change was defined if it exceeded the 95% confidence interval of test-retest variability calculated from the control group in clock-hour sectors 6, 7, 8, 10, 11, and 12. They tested the hypothesis that RNFLT loss is spatially-consistent with the location of DH, and that this loss is more significant in DH eyes than their fellow non-DH eyes after one and two years of DH detection. They also investigated factors associated with a significant RNFL loss in DH eyes.
The authors found that among eyes with DH, 38.5% showed decrease in RNFLT and 6.2% showed increase in RNFLT one year after DH detection. After two years, however, 58.5% showed decrease in RNFLT and no eye showed increase in RNFLT. Among fellow non-DH eyes, 4.6% and 15.4% showed decrease in RNFLT pne and two years after DH detection, respectively. Factors significantly associated with RNFLT loss in DH eyes were recurrent DH and thicker RNFLT at the time of the first sdOCT measurement.
Although the literature on DH and glaucoma progression is thorough, Hwang et al. added new information on its structural features. Notably, significant RNFLT changes could be detected as early as one year after DH detection. This is a great advantage over standard achromatic perimetry (SAP), which requires more frequent testing during a longer follow-up periods due to its inherent larger variability. An important strength of the study was that the authors used the sdOCT test-retest repeatability at each clock-hour of eyes with stable glaucoma to define significant change. Manufacturers should provide these values from their reference databases to help clinicians improve their ability to detect progression in practice.
