Abstract
Purpose::
Spectral domain OCT appears to provide improved resolution of the nerve fiber layer. The purpose of this study was to compare the circumpapillary RNFL measurements using between the time-domain OCT and spectral-domain OCT/SLO in patients without any eye disease and in patients with glaucoma.
Methods::
: A prospective study of patients 18-90 years of age visiting the Eye Clinic and the glaucoma clinic was performed. According to routine examination protocol for all patients, pupils were dilated with phenylephrine 2.5% and tropicamide 1%. After informed consent, time-domain OCT (Humphrey Zeiss Stratus, Dublin CA), spectral-domain OCT/SLO (OTI, Toronto) and standard stereo optic disc photographs of both eyes were obtained. The measurements were analyzed and both OCTs were compared in normal patients and in patients with glaucoma.
Results::
: 25 eyes of 13 normal patients and 19 eyes of 10 patients with glaucoma were included in the study. The mean age of normal patients was 51.08±15.1 and glaucoma patients was 64.1±15.8. The means of the RNFL measurement in normal patients using time-domain OCT was: superior 116.56±12.1µm, nasal 76.36±17.0µm, inferior 122.36±17.4µm, temporal 68.32±11.9µm and the average 95.85±10.4µm. The spectral-domain OCT/SLO measurements using the same subject were: superior 149.8±27.5µm, nasal114.2±26.2µm, inferior 149.12±21.1µm, temporal 91.28±20.0µm and the average 126.12±15µm. In glaucoma patients the time-domain OCT showed: superior 109.52±21.5µm, nasal 75.58±14.6µm, inferior 106.21±20.7µm, temporal 66.42±10.0µm, average 90.33±14.1µm, and the measurements with spectral-domain OCT/SLO were: superior 144.84±30.4µm, nasal 108.79±30.1µm, inferior 133.05±28.9µm, temporal 93.58±26.8µm and the average 119.31±20.2µm. The difference in RNFL measurements were statistically significant, using t test, in all quadrants between the time-domain OCT and spectral-domain OCT/SLO, in normal patients and in patients with glaucoma.
Conclusions::
The circumpapillary RNFL measurements were thicker with spectral-domain OCT/SLO compared with time-domain OCT when evaluated in the same patient. Correction for nerve fiber layer measurements should be considered if instruments when following patients with spectral domain OCT.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • optic disc • nerve fiber layer