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Editors Selection IGR 12-4

Structure Tests and Anatomy: SD-OCT and ppa

Comment by Don Budenz on:

25037 Cross-sectional anatomic configurations of peripapillary atrophy evaluated with spectral domain-optical coherence tomography, Lee KY; Tomidokoro A; Sakata R et al., Investigative Ophthalmology and Visual Science, 2010; 51: 666-671

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This is a cross-sectional study using spectral domain OCT and photographs to elucidate the anatomy of peripapillary atrophy in vivo. As Lee et al. (215) point out, this has been done in vitro, using histological specimens, but the number of subjects studied by this method has been low. The opportunity to delineate retinal layers with OCT creates an opportunity to confirm histological findings in a large number of subjects, in this case, 120 eyes of 120 normal subjects. The study confirms the results of histological studies. There were several anatomic findings of this study. Firstly, it showed that the retinal ganglion cell layer and inner and outer plexiform layers end at the edge of the optic disc while the retinal nerve fiber layer continues into the optic disc cup. Secondly, zone-α peripapillary atrophy shows gradual loss of photoreceptor inner and outer segment layer as one approaches the edge of the optic disc. And thirdly, zone-β peripapillary atrophy shows absence of the RPE layer while other retinal layers terminate before reaching the edge of the optic disc within areas of zone-β peripapillary atrophy. The authors speculate that the latter finding may be due to degeneration of the photoreceptors and overlying layers due to lack of RPE to support them. The scientific methods employed in this study are sound, although the person who performed the OCT readings was not masked to the color photographs. This could potentially bias the readings since the reader would have prior knowledge of the anatomic changes in peripapillary atrophy. Also, while this is an excellent anatomic study, its clinical significance to glaucoma is not addressed in the discussion.

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