Abstract
PURPOSE: To investigate the effects of accommodation on the geometrical parameters of human lens. METHODS: Eight databases from inception to November 2023 were used for the literature search: CNKI, CBM, VIP, Wan-Fang, PubMed, Web of Science, EMBASE, and the Cochrane Library. The Methodological Index for Non-randomized Studies was used to assess the risk of bias. The PRISMA were followed and the following outcomes were taken into consideration: lens diameter (LD), lens thickness (LT), anterior curvature radius (ACR), posterior curvature radius (PCR), lens center position (LCP), and total cross-sectional area (TCSA). This systematic review was registered on an international platform for registered systematic reviews and meta-analysis (INPLASY202260085). RESULTS: A total of 19 studies were included. LT increased by 0.04 mm/D (18 studies; 95% confidence interval [CI], 0.03-0.06; I(2) = 96.6%; P < 0.001). At the same time, LD, ACR, and PCR decreased by 0.06 mm/D (6 studies; 95%CI, -0.07-0.05; I(2) = 50.1%; P < 0.001), 0.53 mm/D (8 studies; 95%CI, -0.64-0.41; I(2) = 96.5%; P < 0.001), and 0.14 mm/D (9 studies; 95%CI, -0.19-0.09; I(2) = 94.7%; P < 0.001) during accommodation, respectively. Moreover, LCP shifted forward by 0.01 mm/D (3 studies; 95%CI, -0.02-0.00; I(2) = 0.0%; P < 0.001), and TCSA by 0.58 mm(2)/D (2 studies; 95%CI, 0.41-1.57; I(2) = 97.0%; P = 0.457) during accommodation. CONCLUSIONS: Changes in LT, LD, ACR, PCR and LCP supported Helmholtz's theory. Different apparatuses or measurement methods influenced the measurement of lens geometrical parameters.