Abstract
Purpose:
To compare axial length and choroidal thickness between individuals with age-related macular degeneration (AMD) and controls.
Methods:
Total 846 eyes of 481 individuals with various degree of AMD and controls with no lesion were recruited. Individuals with other etiology of retinopathy and maculopathy were excluded.The axial length was measured by IOL master. Color fundus photography and optical coherence tomography images were obtained from all participants after pupil dilation. Using color fundus photography, the individuals were classified to various degree of age-related maculopathy accroding to the international Classification and Grading System. Subfoveal choroidal thickness was manually measured using the image of 1-line raster scan through the fovea center obtained by Stratus OCT.
Results:
Total 846 eyes of 481 participants including 471 eyes of no lesion controls, 163 eyes of drusen only, 88 eyes of early AMD, and 124 eyes of late AMD. The average choroidal thickness was 282.65±45.1μm. The mean subfoveal choroidal thickness of late AMD group was 255.5±54.0μm, which is less than other groups (p<0.001)of no lesion (291.1± 35.6μm), drusen only(296.2±38.9μm) and early AMD (285.0±34.5μm). The average axial length was 23.39±1.13mm. The late AMD group has longer mean axial length (23.68±1.94 mm) (95% confidence interval [CI], P = 0.002) compared with other groups ( no lesion:23.41±0.93mm, drusen only:23.19±0.92mm, early AMD:23.24±0.78mm ) . In a multiple regression model, subfoveal choroidal thickness in late AMD decreased by 23.3μm(p<0.001), 25.8μm(P<0.001) and 12.4μm(P=0.012) compared to groups of no lesion, drusen only and early AMD, adjusted for age, axial length and signal strength. The subfoveal choroidal thickness decreased by 15.1 um per mm increase in axial length (95% confidence interval [CI], P< 0.001) adjusted for age, AMD grading and signal strength.
Conclusions:
Longer axial length and reduced subfoveal choroidal thickness were significant in participants with late AMD. Also eyes with longer axial length have thinner choroid thickness. Combination of these two characteristics may contribute to the result and as risk factors of late stage AMD.
Keywords: 412 age-related macular degeneration •
452 choroid •
550 imaging/image analysis: clinical