Topographical variation of macular choroidal thickness with myopia

Area of Science:

• Ophthalmology
• Optometry
• Anatomy

Background:

• Myopia is a common refractive error associated with axial elongation of the eyeball.
• Choroidal thickness variations can be indicative of ocular health and disease.
• Understanding the topographical distribution of choroidal thickness is crucial for studying myopia progression.

Purpose of the Study:

• To investigate the relationship between choroidal thickness variations and myopic features in healthy eyes.
• To utilize spectral domain optical coherence tomography (OCT) for precise choroidal thickness measurements.
• To explore potential correlations between choroidal topography and markers of myopia.

Main Methods:

• Choroidal thickness was measured at five points: foveal center (CTF), and 1.5 mm superior (CTS), inferior (CTI), nasal (CTN), and temporal (CTT) to the fovea.
• Enhanced depth imaging OCT was employed for accurate choroidal thickness measurements.
• Temporal β zone of peripapillary atrophy (βPPA) width was measured, and the ratio of βPPA width to vertical disc diameter (PVDR) was calculated to correct for retinal magnification.

Main Results:

• The study included 85 healthy eyes. Mean axial length was 23.56 ± 0.82 mm and mean refractive error was -0.14 ± 1.80 D.
• Foveal center thickness (CTF) was the thickest, but temporal choroidal thickness (CTT) was thicker than CTF in 36.5% of eyes.
• CTT/CTF ratio showed a negative correlation with refractive error and positive correlations with axial length, βPPA width, and PVDR.

Conclusions:

• A thickened choroid temporally to the foveal center is associated with increased myopia severity in normal eyes.
• These topographical changes in choroidal thickness may result from the stretching of the choroid and sclera during eyeball elongation.
• The findings suggest that choroidal topography is a relevant factor in the structural adaptations associated with myopia.