Choroidal Thickness in Different Degrees of Myopia Measured by Enhanced Depth Imaging Mode Optical Coherence Tomography

Abstract

Background: Choroidal thickness [CT] is associated with many ocular conditions. Different generations of optical coherence tomography [OCT] are important for clinical application.Objective: This study aimed to evaluate the effect of myopia on CT by the use of enhanced depth imaging [EDI] OCT and correlate the measured data with both the axial length [AL] and the refraction.Patients and Methods: A Cross-sectional study included 80 adult patients of both sexes. The patients were divided into 4 groups: [G1, control]: 20 emmetropic subjects. [G2]: 20 myopic patients with refraction up to -6 D. [G3]: 20 myopic patients with refraction >-6 D up to -10 D and [G4]: 20 myopic patients with refraction > -10 D. Spectralis OCT has been utilized in assessing CT in subfoveal region, 500, 1000 and 1500 um temporal and nasal to fovea.Results: A highly statistically significant variation existed among groups considering AL and refraction with G4 having higher values and G2 and G1 having lower values. Regarding CT, the highest value was found in G1 and 2, followed by G3, but the lowest value was found in G4. There was significant positive correlation between refraction in all patients and their AL [p< 0.001], and significant negative correlation appeared between refraction and AL in all patients regarding their all measures of CT [nasal, temporal and subfoveal] [p < 0.001].Conclusion: Myopia with different degrees caused a decrease in CT compared to its thickness of healthy eyes, with marked thinning in advanced myopia.

Keywords

• axial length
• choroid thickness
• myopia
• enhanced depth imaging