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Tiago S. Prata, Mauro T. Leite, Luisa Trancoso, Fabio N. Kanadani, Rafael Furlanetto; Eyes with Large Optic Disc Cupping and Normal Intraocular Pressure: Ability of Spectral-Domain Optical Coherence Tomography to Discriminate those with and without Glaucoma. Invest. Ophthalmol. Vis. Sci. 2012;53(14):814.
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To evaluate the ability of spectral-domain optic coherence tomography (SD-OCT) to differentiate eyes with large physiological optic disc cupping (LPC) from eyes with normal-tension glaucoma (NTG).
Thirty-seven eyes from 24 individuals with NTG and 63 eyes from 33 individuals with LPC were included in this observational case-control study. To be included, glaucomatous eyes had to have untreated intraocular pressure (IOP)<21 mmHg and reproducible glaucomatous visual field (VF) defects. Eyes with LPC required normal VF testing and at least 2 years of follow-up with no evidence of progressive optic neuropathy prior to the imaging session. Also, they were required to have IOP<21mmHg and no previous history of IOP-lowering medications. Parapapillary retinal nerve fiber layer (pRNFL; average, inferior and superior) and macular ganglion cell complex thicknesses (GCC; average, inferior, superior) were obtained using the RTVue SD-OCT. Age-adjusted areas under receiver operating characteristic curves (AUCs) were calculated and compared. To account for the potential correlation between eyes, the cluster of data for the study subject was considered as the unit of resampling when calculating standard errors. In addition, the ability of the normative database for the detection of glaucoma was evaluated. Eyes were considered abnormal if they had at least two borderline (P<0.05, color-coded in yellow) or one abnormal (P<0.01%, color-coded in red) sectors (average, superior and inferior) on either pRNFL or GCC analysis.
Patients with NTG were on average older (52.5y vs 41.2y; P=0.007) compared to individuals with LPC and had an average VF MD of -2.75dB (±2.4). The pRNFL parameter with the largest AUC was the inferior (0.724) followed by average (0.724) and superior (0.618). The GCC parameter with the largest AUC was the inferior (0.735), followed by average (0.703) and superior (0.631). No significant difference was found between the parameters with larger AUCs from pRNFL and GCC analysis (P=0.63). Using the normative database, the pRNFL analysis had sensitivity of 64.86% and specificity of 80.95% while the GCC analysis had a sensitivity of 59.46% and specificity of 80.95%. The combination of the pRNFL and the GCC analysis increased the sensitivity to 78.37% at the cost of specificity (73.01%).
While evaluating patients with normal IOP and large optic disc cupping, SD-OCT was useful to differentiate those with (NTG) and without glaucoma (LPC). Although the diagnostic ability of the pRNFL and the GCC scans were similar, these parameters yielded an increase in sensitivity when combined.
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