Factors Associated with the Signal Strengths Obtained by Spectral

It is generally accepted that structural change precedes functional loss in glaucoma [1-3]. Therefore, accurate eval-uation of structural damage to the optic disc and macula is helpful in early detection of glaucomatous progression. Non-invasive scanning using optical coherence tomogra-phy (OCT) yields valuable quantitative data related to the retinal nerve fiber layer (RNFL) and macular thicknesses. The clinical utility of OCT has been proven in numerous studies. Although good reproducibility of OCT RNFL thickness data has been described [4,5], some studies have indicated that OCT measurements are variable [6]. The data can be significantly affected by OCT image quality. Factors such as the presence of cataracts, the extent of pupillary dilation, and corneal dryness are known to af-fect image quality and the reproducibility of subsequen