Normal Value Ranges for Central Retinal Thickness Asymmetry in Healthy Caucasian Adults Measured by SPECTRALIS SD-OCT Posterior Pole Asymmetry Analysis.

PURPOSE

To determine the normal variation in central retinal thickness asymmetry in healthy Caucasian adults using the posterior pole asymmetry analysis (PPAA) of a SPECTRALIS spectral-domain optical coherence tomography (SD-OCT) device.

METHODS

Healthy Caucasian individuals aged between 18 and 45 years with a visual acuity of minimum 20/20 and a spherical equivalent between -1.5 and +1.5 diopters were recruited. Retinal thickness and retinal nerve fiber layer thickness (RNFL) were using measured SPECTRALIS SD-OCT. Inter- and intraocular differences in central retinal thickness were calculated using the PPAA. The association between age, sex, and interocular asymmetry was evaluated by a linear model with Gaussian correlation structure.

RESULTS

A total of 105 individuals, 30 men and 75 women, were studied. The mean age ± SD was 28.8 ± 7.87 years. The grand mean interocular retinal thickness asymmetry was 5.6 μm (95% confidence interval [CI]: 4.6-6.5) and the grand mean intraocular retinal thickness asymmetry was 8.3 μm (95%

CI

6.8-9.9) in the right eye and 8.4 μm (95%

CI

6.7-10.0) in the left eye. The highest local asymmetries were found in the nasal corners of macula were the posterior pole thickness map overlaps the temporal vascular arches. A slight general age and sex effect on the mean interocular retinal thickness asymmetry was found to be respectively 0.04 μm/year (95%

CI

0.02-0.06 μm) and 0.54 μm (95%

CI

0.19-0.88 μm) for men compared with women.

CONCLUSIONS

Statistically significant physiological asymmetries in inter- and intraocular central retinal thickness exist. This must be considered when early signs of glaucoma or other pathologies are evaluated based on the retinal thickness asymmetry. (http://www.controlled-trials.com/isrctn/ number, ISRCTN09017572.).