**8.2 Fourier domain OCT (FD-OCT) in glaucoma diagnosis**

The newer generation Fourier-domain optical coherence tomography (FD-OCT) technology offers tremendous advances over the traditional time-domain (TD) technology in terms of speed and resolution. Currently, the Cirrus high-definition (HD)-OCT and RTVue 100 are commercially used to quantify peripapillary RNFL thickness in clinical practice. Studies indicate that RNFL thickness parameters measured on Cirrus OCT are reproducible and have high diagnostic sensitivity and specificity in discriminating between healthy and glaucomatous eyes [10, 11]. Furthermore, for the detection of glaucoma RNFL parameters of the RTVue-100 OCT have shown high specificity [12]. Studies indicate that ganglion cells located in the macular area are the earliest cells to be lost in glaucoma and hence this has led to utilize the less explored parameter of various OCT devices, the ganglion cell complex located in the macular region [13].
