Normative values of peripheral retinal thickness measured with Spectralis OCT in healthy young adults.

BACKGROUND

To evaluate the range of peripheral retinal thickness (PRT) in young healthy human subjects by Spectralis HRA + OCT, and to analyze a potential association between the peripheral location, spherical equivalent (SE), axial length (AL), and gender.

METHODS

After pupil dilation, the peripheral retina was scanned by means of six volume protocols (9 × 7.5 mm), each consisting of 31 B-scans. PRT was determined at 4,500, 5,500, 6,500 and 7,500 μm eccentricity from the fovea and the optic nerve head (ONH). Data points were collected every 22.5°. Six additional data points at a distance of 9,000 μm were included. In 11 subjects, OCT measurements were performed twice to evaluate reproducibility. Coefficients of variation (COV) were calculated.

RESULTS

Randomly selected eyes of 50 subjects (19-30 years) with AL of 21-27 mm (SE: -5.75 to +5.25 dpt) were included in the study. Mean PRT decreased significantly (p ≤ 0.001, r = -0.99) towards the periphery, reaching a minimum at 9,000 μm eccentricity (mean PRT: 187.7 ± 8.9 μm). Multiple regression analysis revealed a significant association of PRT with AL at nasal and temporal locations as well as gender for temporal locations. COVs ranged from 0.44 to 2.90 %, with highest COVs found nasal to the fovea.

CONCLUSIONS

This is the first study to report normative data of PRT outside the ETDRS grid and to show a significant continuous almost linear decrease of the RT from the center into the periphery. The data will be valuable to detect peripheral pathologies of the retina in early stages of peripheral retinal dystrophies.