Morphological parameters of the posterior pole in a high myopia population aged over 40 years: a 10-year follow-up study

Abstract

Objective To study the long-term changes of the morphological parameters of the posterior pole in highly myopic patients over 40 years old in Chinese natural population. Methods A population-based follow-up study. The study included 71 patients (27 males, 44 females; 110 eyes) with high myopia who completed the Beijing Eye Study in 2001 and 2011 and had assessable color fundus photographs. The age of the patients in 2011 was 56.2±9.5 years old. According to the definition of pathological myopia by the meta-analysis of the Pathological Myopia Research Group, the fundus photos in 2001 were interpreted, and 110 eyes were divided into groups of simple high myopia (79 eyes) and pathological myopia (31 eyes). The morphological parameters during the 2 follow-up visits in 2001 and 2011 were measured in the color fundus photos, including optic disc tilt ratio, optic disc rotation degree, β zone area, disc-fovea distance, disc-outer β zone border distance, fovea-outer β zone border distance, and vertical distance between temporal arterial arcades, and compared in all the subjects, patients with simple high myopia and patients with pathological myopia. Correlations between the 10-year changes of these parameters and other parameters were analyzed using multiple linear regression analysis. Results In all subjects, the incidence of optic disc tilt and rotation was 41.1% (44/107) and 63.3% (68/107), respectively. The optic disc tilt ratio in 2001 and 2011 was 1.34±0.31 and 1.34±0.33, respectively. The optic disc rotation degree was 30.4±26.3° and 30.0±25.3 in 2001 and 2011, respectively. The differences in optic disc tilt ratio (Z=-0.317, P>0.05) and optic disc rotation degree (t=0.159, P>0.05) were not statistically significant. The β zone area [1.34 (0.45,3.73)mm2, Z=-7.295, P<0.05], disc-fovea distance [(5.18±0.54)mm, t=-3.523, P<0.05], and disc-outer β zone border distance [1.55 (0.24,2.16)mm, Z=-6.825, P<0.05] in 2011 were significantly increased compared to those in 2001 [1.05 (0.23,1.88)mm2, 5.08±0.43, 1.39 (0.77,1.93)mm]. There was no statistically significant difference in the vertical distance between temporal arterial arcades (Z=-1.858, P>0.05). The fovea-outer β zone border distance in the simple high myopia group in 2011 was significantly shorter than that in 2001 (Z=-3.221, P<0.05), while there was no significant change in this parameter in the pathological myopia group (t=0.655, P<0.05). In multivariate analysis, larger β zone area was significantly correlated with longer corneal curvature (r=0.462, P<0.05) and longer axial length (P<0.05). Longer disc-fovea distance was significantly correlated with lower best corrected visual acuity (r=0.348, P<0.05) and longer axial length (P<0.05). Similarly, longer disc-outer β zone border distance was related to lower best corrected visual acuity (r=0.538, P<0.05) and longer axial length (P<0.05). In addition, the progression of myopic maculopathy (Z=-3.425, P<0.05) and the progression from simple high myopia to pathological myopia (Z=-2.911, P<0.05) were both related to enlargement of the β zone. Conclusion For patients with high myopia aged over 40 years, the optic disc morphology is relatively stable, while the disc-fovea distance and β zone area will continue to increase with the progression of myopia. This may be due to the elongation of axial length. Enlargement of the β zone may be a predictor for the progression of myopic maculopathy. (Chin J Ophthalmol, 2021, 57:908-915).