Abstract
Purpose: :
Clinical analysis of macular dimensions in OCT requires reference values for comparison to be valid for diagnostic purposes. It is the purpose of this study to define a normative database of macular thickness in spectral domain optical coherence tomography using the 3D OCT-2000 (Topcon) and to analyze the dependency of the measurements on refraction in healthy adult subjects.
Methods: :
667 eyes of 334 adult persons were scanned using a 3D-OCT 2000 (Topcon Corp., Tokyo, Japan). 65 eyes were hyperopic (+3 to +7.75, mean +4.15 dpt.), 517 eyes were myopic (-4 to -11, dpt, mean -5.67 dpt.), the control group (-0.5<x<+0.5 dpt) comprised 85 eyes. Main exclusion criteria were previous intraocular surgery and preexisting ocular disease. IOP was within the physiological range for all eyes (10-20 mmHg). Sectorial analysis of the 6mm-central retina was performed using the OCT and correlations between the groups were calculated, comparing hyperopic and myopic eyes to the control group. Statistical analysis was performed using SPSS (SPSS, Chicago, IL).
Results: :
Mean foveolar thickness was 8.8 µm higher in the myopic group (p<0.001) compared to the control group. Perifoveal retinal thickness was thinner in the myopic cases (p<0.005), the perifoveal zone accounting for most of the difference (0.05mm3). Again, the hyperopic eyes did not differ significantly from the control group. For the immediate perifoveolar zone (1.5mm around center) there were no significant differences between the three groups (0.48±0.02mm3/ 0.48±0.02mm3/ 0.48±0.02mm3).
Conclusions: :
The reduced perifoveal thickness in conjunction with a higher thickness of the foveola indicates a reduced foveolar depression in high myopic eyes which must be considered when clinically evaluating OCT scans. Other groups have also shown for OCT devices a refraction-dependency of the normal values. This study indicates significant refraction-dependent differences in the microanatomy of the macula, our findings being based on a large number of eyes, providing a solid basis for clinical evaluation of normal and pathological OCT results.
Keywords: clinical (human) or epidemiologic studies: outcomes/complications • imaging/image analysis: clinical • retina