Comparison between degree of hyperopia and iridocorneal angle, cross-sectional study

Objectives: To determine whether there is a correlation between the degree of hyperopia and the presence of a narrow iridocorneal angle (ICA) in the general population. Methods: Cross-sectional study, period December 2022 - June 2023 at the Instituto de la Visión, Chile. Sample size of 177 patients (353 eyes). Hyperopes are classified as mild (less than 3 dioptres), moderate (3 to 6 dioptres), or high (greater than 6 dioptres). The AIC, assessed by gonioscopy (4-mirror gonioscope), according to Shaffer in 4 degrees, dichotomised from 0 to 2 as narrow angle, and 3 to 4 as open. An emmetropic "control" group was maintained, with a range of +/- 0.5 spherical dioptres. Statistical analysis: The chi-square test was used for the association between the two variables. Results: Of the total number of patients, 65% had mild hyperopia (n=229), 13% moderate (n=47), 0.6% high, while 21% corresponded to the "control" group (n=75). Of the total, 41% had narrow angle (n=146) and 59% open (n=207). In the analysis by group, mild hypermetropes showed 46% (n=105) of narrow angles compared to 27% (n=20) of the 'control' group. This difference was statistically significant (p<0.05). When comparing the moderate hyperopia group, which had 40.4% (n=19) of narrow angles, significant differences were observed compared to the 'control group', but not compared to the mild hyperopia group (p=0.2). Conclusion: There is a significant association between hyperopia and narrow AIC measured by gonioscopy, independent of the degree of severity of hyperopia. It is therefore advisable to screen for narrow angles in these patient groups.