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Editors Selection IGR 19-4
Structural Examination Methods: Beta-PPA by SD-OCT
Comment by Kaweh Mansouri on:
27019 In-Vivo Microstructural Anatomy of {beta}-Zone Parapapillary Atrophy in Glaucoma., Park SC; De Moraes CG; Tello C et al., Investigative Ophthalmology and Visual Science, 2010; 51: 6408-6413
Assessment of parapapillary atrophy has become part of the morphologic diagnosis of glaucoma. It is commonly assumed that presence of β-zone parapapillary atrophy (β-PPA) is a risk factor for glaucomatous damage as well as its progression (Uchida H, et al. Ophthalmology 1998; 105: 1541- 1545). Although it was described more than eighty years ago, its pathophysiology has been insufficiently studied. Our understanding of β-PPA has so far been based mostly on histologic studies showing atrophied or degenerated outer retinal layers. Histologic specimen, however, are limited by alterations of the normal in-vivo architecture. Park et al. (1728) in this seminal paper, quantitatively assessed the microstructural anatomy of β-PPA by using spectral-domain OCT (SD-OCT). Color photographs and SD-OCT images of the optic disc and parapapillary retina were obtained in 24 eyes of patients with established or suspect glaucoma. They have put modern technology to good use and, indeed, they present interesting information. They found that, contrary to common wisdom, the clinical β-PPA area was not completely denuded of retinal pigment epithelium (RPE): in 35% RPE was present within the β-PPA. There also was an area of photoreceptor degeneration outside the clinical β-PPA zone. With a paucity of data on the relationship of β-PPA enlargement and glaucoma progression, the clinical usefulness of β-PPA evaluation remains disputed. It has previously been suggested that with a sensitivity and specificity of 6.2%/99.2%, the currently tedious evaluation of β-PPA enlargement might not be appropriate for the routine follow-up of glaucoma patients (Budde WM, Jonas JB. Am J Ophthalmol 2004; 137: 646-654). Therefore, before progression of β-PPA can be used as a marker for glaucoma progression, innovative tools are required to reliably quantify β-PPA and detect changes in a clinical setting. Park et al.'s findings further suggest that our current definition of β-PPA should be modified.
References
- Uchida H, Ugurlu S, Caprioli J. Increasing peripapillary atrophy is associated with progressive glaucoma. Ophthalmology 1998;105(8):1541-5.
- Park SC, De Moraes CG, Tello C, et al. In-vivo microstructural anatomy of beta-zone parapapillary atrophy in glaucoma. Invest Ophthalmol Vis Sci 2010;51(12):6408-13.
- Budde WM, Jonas JB. Enlargement of parapapillary atrophy in follow-up of chronic open-angle glaucoma. Am J Ophthalmol 2004;137(4):646-54.
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