: PRéCIS: Superior oblique palsy (SOP) eyes show thinner inferotemporal retinal nerve fiber layer (RNFL) without adjusting for foveal position. There was a strong correlation between the degree of torsion and the difference in the RNFL thickness before and after adjusting foveal location. PURPOSE: The impact of foveal position on RNFL thickness has been shown. In this study, we evaluate RNFL thickness profiles according to the disc-foveal angle in SOP and control eyes. MATERIALS AND METHODS: In 44 eyes of 22 patients with unilateral congenital SOP and 42 eyes of 42 normal controls, the position of the fovea relative to the optic disc was calculated by optical coherence tomography using FoDi (fovea-to-disc) technology. After measuring RNFL thickness with FoDi alignment technology, each optical coherence tomography image was reevaluated with FoDi turned off, and the measurements were repeated to determine RNFL values according to the disc-foveal angle. RESULTS: The average disc-foveal angle was -10.85±6.60 degrees and -10.71±6.63 degrees in the affected and fellow eyes of SOP patients; these values were significantly greater than control subjects (-5.88±4.09 degrees). There was no significant difference in RNFL sector values between SOP and control eyes with FoDi. From all RNFL sectors, the measured inferotemporal thickness was less in SOP eyes without FoDi than in SOP eyes with FoDi (129.7±20.5 µm vs. 144.6±17.8 µm, respectively, P=0.001). Differences of the RNFL thicknesses with and without FoDi in SOP eyes in the superotemporal and inferotemporal sectors were 5.40±13.42 and 14.84±15.00, respectively, which were significantly more than the same changes in control eyes with amount of 0.30±6.57 and 8.52±10.4 (P=0.02 for both sectors). CONCLUSIONS: In SOP eyes with large amounts of torsion, a correction for the disc-foveal angle is necessary for accurate determination of the RNFL thickness profile.
Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran.