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Editors Selection IGR 18-3
Clinical Examination Methods: RGC loss and disc hemorrhage
Comment by Ki Ho Park on:
58999 Estimated rates of retinal ganglion cell loss in glaucomatous eyes with and without optic disc hemorrhages, Gracitelli CP; Tatham AJ; Zangwill LM et al., PLoS ONE, 2014; 9: e105611
In contrast to the previous studies on structural and functional changes in glaucoma associated with disc hemorrhage, the current study has introduced a new concept of retinal ganglion cell (RGC) loss estimation in glaucoma patients with or without disc hemorrhage. RGC number estimation was proposed by Medeiros et al. in a series of previous reports. Even though the formulas for RGC number estimation have been derived empirically in studies on a primate model of glaucoma, they have been validated with human cohorts.
The authors found the rate of RGC loss to be twice as fast in their disc hemorrhage group (22,233 cells/year) than in their no-hemorrhage group (10,704 cells/year). In the latter group, no disc hemorrhage was detected during follow up (average: 3.74 ±} 0.85 years). Also associated with faster rates of progression was a higher mean IOP during follow-up. Even after adjusting for confounding variables, however, the effect of disc hemorrhage on the estimated RGC loss rate remained significant. Overall, the study supports the current evidence that the presence of disc hemorrhage should be considered to be an indicator of increased risk of faster optic nerve damage in glaucoma.
The rate of RGC loss is two-times faster in the disc hemorrhage group than in the no-hemorrhage group (in which no disc hemorrhage was detected during follow up)
The study has limitations, in that (1) there might have been cases of missed detection of disc hemorrhage; and (2) the recorded hemorrhages occurred at any time during the rate calculation period, not at the beginning. Nonetheless, this new approach does strengthen the existing evidence on the association of hemorrhage with the rate of glaucoma progression.
It will be interesting to focus the current study into the regional rate of RGC loss after developing a new formula for estimated regional RGC number or using additional tool such as regional RGC layer and inner plexiform layer thickness analysis in disc hemorrhage cases.
References
- Medeiros FA, Lisboa R, Weinreb RN, et al. A combined index of structure and function for staging glaucomatous damage. Arch Ophthalmol 2012;130:1107-1116.
- Medeiros FA, Zangwill LM, Anderson DR, et al. Estimating the rate of retinal ganglion cell loss in glaucoma. Am J Ophthalmol 2012;154:814-824.
- Medeiros FA, Zangwill LM, Bowd C, Mansouri K, Weinreb RN. The structure and function relationship in glaucoma: implications for detection of progression and measurement of rates of change. Invest Ophthalmol Vis Sci 2012;53:6939-6946.
- Kim KE, Yoo BW, Jeoung JW, Park KH. Long-Term Reproducibility of Macular Ganglion Cell Analysis in Clinically Stable Glaucoma Patients. Invest Ophthalmol Vis Sci 2015; March 31. [Epub ahead of print]
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