AIM: To analyze the clinical manifestations and etiological factors of high myopia in 320 cases.

METHODS:A total of 320 patients(640 eyes)with high myopia treated in Ningxia Eye Hospital from January 2011 to November 2012 were studied. All of them underwent thorough eye examination and relevant environmental factors were recorded. The following data were analyzed, including gender, ethnicity, age of onset, refractive error, axial length, best corrected visual acuity(BCVA), educational level and living environment.

RESULTS: Bilateral high myopia was present in 320 patients(130 men and 190 women; 250 being of Han nationality and 70 of Hui nationality)with a mean age of 42.65±16.51 years(range: 3-80 years); the male to female ratio was 1:1.5. The age of onset was lower than 20 years in 237 patients, higher than 21 yeas in 83 patients, the difference was statistically significant(P<0.001). There was no significant difference between diopter and educational level(P>0.05). The patients with BCVA higher than 0.3 increased with diopter increased, while BCVA lower than 0.8 and between 0.4～0.7 reduced. Refraction was significantly negatively correlated with BCVA(r=-0.196, P<0.05)and positive correlated with axial length(r=0.681, P<0.05).

CONCLUSION: In the study, patients with high myopia tend to have early onset, low educational level, and spacious living environment. Such results indicate that the genetic factors may be the main cause of high myopia in this group. The higher the degree of myopia was, the worse BCVA and the longer AL would be.