[Analysis of the cognitive effects of monocular blindness and related influencing factors]

Objective: To investigate the cognitive effects of monocular blindness and related influencing factors. Methods: A cross-sectional study was conducted. The patients with monocular blindness (the age of onset <16 years) were enrolled from Beijing Tongren Eye Center, Beijing Tongren Hospital between January 2018 and June 2020. The Montreal cognitive assessment (MoCA) scale was applied to assess seven cognitive domains including visuospatial and executive function, naming, attention, etc. Based on MoCA scores, all the patients were classified into two groups: normal cognitive functions and cognitive impairment. Spearman's correlation was used to perform the single factor analysis of the influencing factors of cognitive functions. Multivariate linear regression analyses were applied to identify the independent influencing risk factors. Results: A total of 45 patients with monocular blindness were enrolled. There were 25 males and 20 females, with age at testing being (27±10) years.The incidence of cognitive impairment in 45 patients was 60.0% (27/45). The abnormal items ranking from a high to low rate were language (95.6%, 43 cases), delayed recall (75.6%, 34 cases), visuospatial and executive function (60.0%, 27 cases), abstract (44.4%, 20 cases), attention (35.6%, 16 cases), naming (20.0%, 9 cases), and orientation (0%). There were statistically significant differences (all P<0.05) in total score (21.9±3.3 vs. 27.4±1.4), visuospatial and executive function (3.2±1.7 vs. 4.6±0.7), naming (2.7±0.6 vs. 2.9±0.2), attention (5.3±1.0 vs. 5.8±0.4), language (1.1±0.8 vs. 1.8±0.8), abstract (1.1±0.8 vs. 1.8±0.5) and delayed recall (2.3±1.3 vs. 4.4±0.8) between two groups of patients with and without cognitive impairment. Spearman's correlation analysis showed visuospatial and executive functions, attention, abstract and MoCA total score were positively correlated with education years (correlation coefficients being 0.355, 0.424, 0.434 and 0.370, respectively; all P<0.05). Multiple linear regression showed that duration of blindness was correlated with naming (β=-0.325), and years of education correlated with attention (β=0.472), abstract ability (β=0.441) and MoCA total score (β=0.390) (all P<0.05). Conclusions: Monocular blindness may affect language, delayed memory and visuospatial executive functions. The duration of blindness is an independent risk factor, and higher education is a protective factor of the cognitive impairment.