Optical coherence tomography, frequency-doubling technology, and colour Doppler imaging in ocular hypertension

Abstract

To study in ocular hypertension (OH) the retinal nerve fibre layer (RNFL) with optical coherence tomography (OCT) and the neuronal function with frequency-doubling technology (FDT) to assess which of the two methods was more sensitive in detecting early glaucomatous damage. Furthermore, a colour Doppler imaging (CDI) of the optic nerve was carried out to highlight any correlation with RNFL thickness and FDT abnormality. We enrolled 28 ocular hypertensive patients who underwent OCT of the RNFL and FDT. Moreover, we performed a CDI of the ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary arteries (PCAs). The patients with OH following OCT revealed a significant thinning in the RNFL as compared to the control group only in the inferior quadrant: 122.250+/-14.091 vs131.750+/-10.729 mum (P<0.045). As regards FDT, there was a significant difference between the two groups only for pattern standard deviation (PSD): 3.873+/-1.488 vs1.938+/-0.704 dB (P<0.044). In OH and in the control group, CDI resistance index (RI) in the OA was 0.768+/-0.012 vs0.745+/-0.019 (P<0.022), in the CRA was 0.66+/-0.012 vs0.645+/-0.019 (P<0.032), and in PCAs was 0.673+/-0.039 vs0.622+/-0.012 (P<0.037). The OCT had a sensitivity of 83% but only in the inferior RNFL quadrant. The FDT-PSD revealed a sensitivity of 85%. Both FDT and OCT detect early glaucomatous damage with a slightly superior sensitivity of FDT vsOCT. The CDI measurements suggest that circulatory abnormalities may have a role in the development of OCT and FDT damage.