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

Abstract

Purpose: 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. Materials and methods: 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). Results: 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 μm (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%. Conclusions: 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.