Changes in Retinal Nerve Fiber Layer After Acute Primary Angle Closure: Reply

Abstract

In our report on the changes in retinal nerve fiber layer (RNFL) thickness after acute primary angle closure (APAC), eyes with APAC were examined prospectively at 2 weeks and then 16 weeks after presentation, looking specifically for changes in the GDx (Laser Diagnostic Technologies, San Diego, CA) parameters. We found a decrease in superior and inferior average RNFL thicknesses, superior and inferior ratios, maximum modulation, and ellipse modulation in APAC-affected eyes, but none in the fellow eyes.In contrast, the studies by Lai et al 1Lai J.S. Tham C.C. Chan J.C. et al.Scanning laser polarimetry in patients with acute attack of primary angle closure.Jpn J Ophthalmol. 2003; 47: 543-547Crossref PubMed Scopus (11) Google Scholar and Tsai and Chang 2Tsai J.C. Chang H.W. Scanning laser polarimetry in patients with acute angle-closure glaucoma.Eye. 2004; 18: 9-14Crossref PubMed Scopus (18) Google Scholar were cross-sectional studies performed at 6 months and 1 month after APAC, respectively. Thus, any differences in RNFL measurements found at these time points must be interpreted with caution. As there was no baseline measurement, one cannot be sure when or how the RNFL changed with respect to the APAC episode. For example, some individuals may have suffered elevated intraocular pressure with RNFL damage before the acute attack, and this may be independent of the severity or duration of APAC.Although we found changes in RNFL after APAC, it is not known if these changes are associated with the development of glaucomatous optic neuropathy. It is possible that structural changes in RNFL may be subclinical and not lead to optic disc changes. Until this is established, we feel that it is still appropriate to use the term APAC and to drop the word glaucoma from the nomenclature of the disease for cases that do not develop glaucomatous optic neuropathy and visual field loss. In our report on the changes in retinal nerve fiber layer (RNFL) thickness after acute primary angle closure (APAC), eyes with APAC were examined prospectively at 2 weeks and then 16 weeks after presentation, looking specifically for changes in the GDx (Laser Diagnostic Technologies, San Diego, CA) parameters. We found a decrease in superior and inferior average RNFL thicknesses, superior and inferior ratios, maximum modulation, and ellipse modulation in APAC-affected eyes, but none in the fellow eyes. In contrast, the studies by Lai et al 1Lai J.S. Tham C.C. Chan J.C. et al.Scanning laser polarimetry in patients with acute attack of primary angle closure.Jpn J Ophthalmol. 2003; 47: 543-547Crossref PubMed Scopus (11) Google Scholar and Tsai and Chang 2Tsai J.C. Chang H.W. Scanning laser polarimetry in patients with acute angle-closure glaucoma.Eye. 2004; 18: 9-14Crossref PubMed Scopus (18) Google Scholar were cross-sectional studies performed at 6 months and 1 month after APAC, respectively. Thus, any differences in RNFL measurements found at these time points must be interpreted with caution. As there was no baseline measurement, one cannot be sure when or how the RNFL changed with respect to the APAC episode. For example, some individuals may have suffered elevated intraocular pressure with RNFL damage before the acute attack, and this may be independent of the severity or duration of APAC. Although we found changes in RNFL after APAC, it is not known if these changes are associated with the development of glaucomatous optic neuropathy. It is possible that structural changes in RNFL may be subclinical and not lead to optic disc changes. Until this is established, we feel that it is still appropriate to use the term APAC and to drop the word glaucoma from the nomenclature of the disease for cases that do not develop glaucomatous optic neuropathy and visual field loss. Changes in the RNFLOphthalmologyVol. 112Issue 7PreviewWe read with great interest Aung et al’s article. 1 Two similar reports have been published recently by Lai et al 2 and Tsai and Chang. 3 There are important similarities and differences between these 3 studies, in both the study design and the results. We attempt to review and summarize the differences in Table 1. Full-Text PDF