Abstract
Purpose: :
Good quality images of scanning laser instruments are essential for reliable diagnosis and management of glaucoma. In daily routine, patients sometimes have dilated pupils, but sometimes not. Fourier Domain Optical Coherence Tomography is a new technology for high resolution imaging of the optic nerve head and the retinal nerve fiber layer (RNFL). The aim of this study was to evaluate possible differences in optic disc topographic and RNFL measurements when measuring eyes with and without pupil dilation.
Methods: :
100 eyes of 100 early glaucoma patients and 50 eyes of 50 healthy age matched subjects were included. Early glaucoma was defined as an abnormal visual field with a mean deviation [MD] of ≤ 9 dB and/or pattern standard deviation [PSD] ≤ 8% and/or corrected loss variance [CLV] of ≤ 64 dB². Healthy subjects had at least one normal reliable result on standard automated perimetry (SAP). Optic disc topographic measurements and RNFL measurements were performed consecutively on one day (first undilated following by dilation). Differences in optic disc topographic parameter and RNFL values between dilated and non-dilated eyes were analysed using a paired t-test.
Results: :
The mean pupil diameter without dilation was 3,8 +- xx mm and with dilation 7,7+- xx mm. Measurements with dilation were easier and faster. The signal strengh index (quality index) was equal between both groups. Normal subjects showed no significant change in optic disc topographic and RNFL measurements after dilation. We found that glaucoma patients had a significant higher thickness of RNFL average (p<0.001) and of RNFL in the superior hemisphere (p<0.005) after dilation. All other disc and RNFL parameter did not show a significant difference between dilated and undilated eyes.
Conclusions: :
FD-OCT imaging with dilated pupils was easier and faster. After dilation no significant difference in optic disc measurements was found in glaucoma and healthy subjects. Dilated glaucoma eyes showed a thicker RNFL compared to undilated eyes. Further studys will investigate the influence of glaucoma stage, age or lence opacity on the measurements of optic disc and RNFL with Fourier-domain OCT.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • optic disc • nerve fiber layer