Normality curves of Choroidal Thickness, Central Macular Thickness, Macular Volume and n Nerve Fiber Layer Thickness in healthy subjects from an ophthalmological reference hospital in Mexico city, measured by spectral domain optical coherence tomography (SD-OCT).

Abstract

Purpose: To define anatomic normality curves of different retinal and choroidal variables in healthy subjects using SD-OCT.

Methods: Prospective, transversal, observational and descriptive study realized at an ophthalmological reference hospital from August 2013 to December 2013. Healthy subjects were selected by consecutive recruitment analyzing one eye for retinal and choroidal variables, and both eyes for posterior pole and nerve fiber layer symmetry. Inclusion criteria was: age between 18 and 69 years old, a spherical refractive error from +2.00 to -9.00, cup-to-disc ratio ≤0.5 and intraocular pressure less than 18 mmHg. Patients with media opacities, chronic systemic diseases and other ophthalmological disease were excludeed. Images were obtained according to a standardized protocolo analyzing right eyes first. Retinal and nerve fiber layer were automatically analyzed by custom software and choroidal variables were manually segmentated with previous validation of measurements.

Results: A total of 25 patients were included. 11 males and 14 females with a mean age of 34 ±11.9 years (range 18 to 66). Results were reported for central and sectorial thickness. Main values of central thickness were as follows: Foveal central thickness (FCT) 221.8 μm±20; choroidal central thickness (CCT) 297.5μm±52.2; global retinal volume (GRV) 8.8 mm3±0.33; global choroidal volumen (GCV) 4.8 mm3 ± 0.78; nerve fiber layer assymetry (NFL) by quadrants: superior -6.7μm±9.1, temporal -3.8μm±7.8, nasal 15.2μm±13.2 and inferior 5.2 μm±7.6. Retinal thickness was higher at temporal sectors while choroidal thickness was higher at superior sector. Nerve fiber layer assymetry by quadrants was more significant at nasal sector. A comparative analysis of FCT, CCT, GRV, GCV and NFL between males and females was done demonstrating no statistically significant difference (p>0.05).

Conclusions: Based on our results, we conclude that retinal and choroidal thickness depends on its location and that there is no relation between gender and retinal/choroidal thickness. By determining normal values in healthy population, normality curves databases will increase in number, and consecutively it will be possible to objectively determine pathology in latin population.

Keywords: 465 clinical (human) or epidemiologic studies: systems/equipment/techniques • 452 choroid • 688 retina