Methods: The study group consisted of 18 high myopia patients with 29 eyes and 24 degenerative myopia patients with 36 eyes. Axial length, central fovea and subfoveal choroidal thicknesses of the subjects were compared. The degenerative group had severe myopia with a refractive error of -6D and above. In addition, a control group of 31 emmetropic patients with 62 eyes was included in the study. The subjects received a check-up at the beginning. It included inquiry of systemic and ocular disease, Snellen chart corrected visual acuity (BCVA) and intraocular pressure measurement, an axial length measurement of the eye by Aviso Ultrasonographic and biometric devices in A mode, biomicroscopic examination, detailed fundus examination, and measurements of the central fovea and subfoveal choroidal thickness by DRI HD-OCT SS Triton device. Statistical analysis was done with SPSS 11.5 program. Paired t-test was used to evaluate the relationship among the groups.

Findings: No correlation existed between axial length and CFT, but a negative correlation between axial length and SFCT in the high and degenerative myopia groups (r = -0.459 and r = -0.051, p = 0.431).The thinnest SFCT was found in degenerative myopia group (123.97?m) and the thickest in the emmetropic subjects (291.12?m).

Result: As axial length increases, central foveal thickness remains constant, while subfoveal choroidal thickness decreases. However, increased axial length alone did not affect BCVA in high myopia subjects, while signifi cantly reduced BCVA in the degenerative group. Keywords : Axial length, Central foveal thickness (CFT), Subfoveal choroidal thickness (SFCT), Optical coherence tomography (OCT)