Retinal Nerve Fiber Layer Imaging with Spectral-Domain Optical Coherence Tomography

Strategies to improve early diagnosis in glaucoma

“…See and colleagues reported an age-related decrease in average neuroretinal rim area, measured using CSLO, of 1.25 Â 10 À3 mm 2 per year in healthy controls over an average follow-up period of more than 7 years (See et al, 2009). Although SDOCT is a relatively new technology and longitudinal studies are still of fairly short duration, Leung and colleagues followed 35 normal individuals for an average of 30 months and found a similar age-related decrease in RNFL thickness, with a 0.52 mm per year decrease in average cpRNFL thickness (95% CI 0.17-0.86 mm per year) (Leung et al, 2012). Age-related rates of structural change may however vary between individuals and be affected by factors such as baseline cpRNFL thickness, ethnicity, disc area, and signal strength (Grewal and Tanna, 2013;Knight et al, 2012;Leung et al, 2012).…”

“…Imaging devices provide an objective means to obtain high-resolution topographic images of the optic nerve head and RNFL and to quantify characteristics of these structures (Chang et al, 2009;Greaney et al, 2002;Jaffe and Caprioli, 2004;Leung et al, 2009Leung et al, , 2010Medeiros et al, 2004bMedeiros et al, , 2005bMedeiros et al, , 2008Mwanza et al, 2012;Naithani et al, 2007;Wollstein et al, 1998Wollstein et al, , 2000Zangwill et al, 2001). In addition, imaging devices contain normative databases that allow one to determine the probability that observed measurements are within the normal range and to potentially detect glaucoma at an earlier stage ( Fig.…”

“…The original OCT technology of time-domain OCT (TDOCT) has been superseded by spectral domain OCT (SDOCT), which offers enhanced image quality due to improved spatial resolution and averaging of multiple images within each scan, made possible by a faster scan speed. Due to these improvements, SDOCT has lower measurement variability than TDOCT, with evidence that it is better at detecting glaucoma progression than the older technology (Leung et al, 2009. OCT imaging in glaucoma has traditionally focused on the optic nerve head and surrounding RNFL, or the circumpapillary RNFL (cpRNFL); however, there is growing appreciation of the importance of the macula in glaucoma and in recent years increasingly sophisticated SDOCT segmentation software has become available that allows more accurate segmentation of the inner retinal layers (Mwanza et al, 2012).…”

“…SDOCT has been shown to perform similarly, or slightly better, but with improved reproducibility (Leung et al, 2009;Park et al, 2009;Vizzeri et al, 2009). Using the Cirrus SDOCT (Carl Zeiss Meditec Inc.), Leung and colleagues found SDOCT cpRNFL measurements to have a sensitivity of 91.6%, for a specificity of 87.6%, and an area under the ROC curve of 0.962 (Leung et al, 2009).…”

“…1), confocal scanning laser ophthalmoscopy (CSLO), and scanning laser polarimetry (SLP), that obtain objective quantitative measurements of ocular structure and can detect glaucoma at an earlier stage (Chang et al, 2009;Greaney et al, 2002;Huang et al, 1991;Leung et al, 2009Leung et al, , 2010Medeiros et al, 2004bMedeiros et al, , 2005bMedeiros et al, , 2008Mwanza et al, 2012;Naithani et al, 2007;Weinreb et al, 2014;Wollstein et al, 1998Wollstein et al, , 2000Zangwill et al, 2001). In addition to evaluating the optic nerve head and RNFL, imaging devices have also recently been used to evaluate inner layers of the glaucomatous macula Mwanza et al, 2012Mwanza et al, , 2014.…”