Purpose: To investigate whether retinal thickness varies with refractive error. Also secondary to see if there is any difference in retinal thickness between the right and left eye. Methods: The inclusion criteria for the study was subjects without any pathologies, age between 18-45 and refractive error of maximum +0.75 SER and the myopia had no limit, as well as no astigmatism higher then -1.00D. Subjects, which fitted the inclusion criteria for the study, was shown to the OCT room were retinal thickness measurements were acquired first on the right and then left eye. To get the same reading area, the same setup was used and the fixation point was always centered for each patient. After all subjects had undergone the same method the results were analyzed using t-test and regression analysis. Results: The analysis showed a difference between emmetropic eyes and myopic eyes in the peripheral retinal thickness, having the myopes being significantly thinner. The inter myopic analysis showed no difference in retinal thickness in any of the points. This could however be due to the smaller sample size. The comparison between right and left eye showed a good symmetry between the two eyes both in the emmetropic and the myopic group. Conclusions: From this study we can conclude that the myopic group has a thinner peripheral retinal thickness than the emmetropic group. Central retinal thickness is not significantly different but could be due to the smaller sample size. There is no difference in retinal thickness between right and left eye.

Aim: To evaluate repeatability and reproducibility of macular thickness measurements in visually normal eyes using the Topcon 3D OCT-1000. Methods: Phase 1 investigated scan repeatability, the effect of age and pupil dilation. Two groups (6 younger and 6 older participants) had one eye scanned 5 times pre and post- dilation by 1 operator. Phase 2 investigated between-operator, within and between-visit reproducibility. 10 participants had 1 un-dilated eye scanned 3 times on 2 separate visits by 2 operators. Results: Phase 1: No significant difference existed between repeat scans (p=0.75) and no significant difference was found pre- and post-dilation (p=0.54). In the younger group variation was low (95% limits ± 3.62 m) and comparable across all retinal regions. The older group demonstrated greater variation (95% limits ± 7.6 m). Phase 2: For a given retinal location, 95% confidence limits for within-operator, within-visit reproducibility was 5.16 m. This value increased to 5.56 m for the same operator over two visits and to 6.18 m for two operators over two visits. Conclusion: A high level repeatability, close to 6 m, of macular thickness measurement is possible using the 3D OCT- 1000. Measured differences in macular thickness between successive visits that exceed 6 m in pre-presbyopic individuals are therefore likely to reflect actual structural change. OCT measures are more variable in older individuals and it is advisable to take a series of scans so that outliers can be more easily identified.