Retinal Nerve Fiber Layer Thickness in Normal, Ocular Hypertensive, and Glaucomatous Indian Eyes An Optical Coherence Tomography Study Jamyang Gyatsho, MD, Sushmita Kaushik, MD, Amod Gupta, MD, Surinder Singh Pandav, MD, and Jagat Ram, MD Purpose: To determine retinal nerve fiber layer (RNFL) thickness measurements in normal, ocular hypertensive (OHT), and glaucomatous Asian Indian eyes. Methods: This prospective observational cross-sectional study included patients with OHT, primary open angle glaucoma (POAG), and age-matched normal controls. The global and 4-quadrant average RNFL thickness was measured using the Stratus OCT. The main outcome measures were differences in RNFL thickness measurements between the 3 groups. The discriminating power of each parameter was evaluated by calculating areas under receiver operating characteristic curves (AROCs). Results: Twenty-three eyes of 23 POAG patients, 24 eyes of 24 OHT, and 48 eyes of 48 normal controls were analyzed. The superior, inferior, and global RNFL measurements were significantly thinner in OHTs compared with normals (P = 0.031, 0.019, and 0.022, respectively). All 5 RNFL parameters were significantly thinner in the POAG group compared with OHT group (P <0.001). Parameters with largest AROCs for distinguishing glaucoma from OHT were average and inferior average RNFL measurements (0.989 and 0.979, respectively). Inferior and superior RNFL measurements had largest AROCs (0.717 and 0.700, respectively) to distinguish OHT from normal eyes. Conclusions: Stratus OCT detected significant quantitative differences in RNFL thickness between normal, OHT, and glaucomatous Asian Indian eyes. Key Words: optical coherence tomography, Indian eyes, retinal nerve fiber layer thickness, ocular hypertensive, glaucoma (J Glaucoma 2008;17:122–127) I t is now widely believed that primary open angle glaucoma (POAG) represents a glaucoma continuum, where there is progressive retinal nerve fiber layer (RNFL) loss as the disease progresses through the stages of clinically undetectable disease where the patient is apparently normal, early preperimetric glaucoma with nerve fiber defects and/or ocular hypertension (OHT), and manifest POAG. 1 RNFL defects have been clinically demonstrated earlier than visual field defects, 2 and objective RNFL thickness measurement is now possible with newer investigative modalities like optical coherence tomography (OCT) and scanning laser polarimetry (GDx). OCT has been widely used for measuring the RNFL thickness in normal, glaucoma suspect, and glaucomatous eyes. 3–6 The recently introduced Stratus OCT has better resolution than the older versions by virtue of acquiring increased number of A-scans and it has also incorporated the new feature of probability of likelihood of abnorm- ality after comparison with an internal normative database. Significant differences have been reported between ocular hypertensive (OHT) and glaucomatous eyes compared with normal eyes. 3–6 However, studies using the Stratus OCT in normal Asian Indian eyes 7,8 and normal Chinese eyes 9 have also demonstrated signifi- cantly thicker RNFL thickness measurements in the global average, as well as average inferior and superior RNFL thickness measurements compared with white eyes. 10–12 This may be due to racial differences in RNFL measurements in the populations studied, which may also have a bearing on the differences in RNFL measurements in normal, OHT, and glaucomatous eyes. We carried out this study to ascertain the RNFL thickness measurements in normal, OHT, and glaucoma- tous Asian Indian eyes and to compare it with published values in white eyes. METHODS This was a prospective observational cross-sectional study including patients with OHT and POAG presenting to the Glaucoma Clinic of the Department of Ophthal- mology, Postgraduate Institute of Medical Education and Research, Chandigarh, India. Normal controls were selected from age and sex-matched healthy volunteers Copyright r 2008 by Lippincott Williams & Wilkins Received for publication March 8, 2007; accepted June 30, 2007. From the Department of Ophthalmology, Postgraduate Institute of Medical Education and Research, Chandigarh, India. No author has any proprietary interest in any of the products mentioned in this paper. Reprints: Sushmita Kaushik, MD, Advanced Eye Centre, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India (e-mail: sushmita_kaushik@yahoo.com). ORIGINAL STUDY 122 J Glaucoma  Volume 17, Number 2, March 2008