Analysis of anterior chamber and lens characteristics in age-related cataract patients with zonular weakness based on CASIA2

Objective  To analyze the biological parameters of the anterior segment of age-related cataracts patients with or without zonular weakness with the new generation of sweep-source anterior optical coherence tomography (OCT) device CASIA2 to provide a basis for the diagnosis of zonular weakness.

Methods  A case-control study was conducted.A total of 158 cases (186 eyes) of patients with age-related cataracts having zonular weakness as a zonular weakness group, and 80 cases (80 eyes) of cataract with age-related cataracts without zonular weakness as a normal zonule group were enroll from June 2022 to June 2023 at Beijing Tongren Hospital.All patients underwent routine preoperative ophthalmological examination including slit lamp microsopy, IOLMaster 700, ocular B-ultrasound and OCT.The anterior chamber depth (ACD), anterior chamber volume (ACV), lens thickness (LT), lens vault (LV), anterior chamber angle opening distance at 750 μm (AOD750), lens decentration and tilt, radius of curvature of the anterior lens surface (RAL), and radius of curvature of the posterior lens surface (RPL) of patients were measured with CASIA2 and compared between the two groups.The relationship between zonular weakness and anterior chamber parameters and lens parameters was evaluated by logistic regression analysis.This study followed the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Beijing Tongren Hospital (No.TRECKY2018-049), and all enrolled patients signed the informed consent form.

Results  In the zonular weakness group, ACD, ACV, RAL, and AOD750 were (2.34±0.56)mm, (85.05±40.19)mm ³, 7.52 (7.13, 8.08)mm, and 0.27 (0.07, 0.30)mm, respectively, which were smaller than (3.13±0.38)mm, (127.75±38.15)mm ³, 9.28(8.51, 9.76)mm, and 0.52 (0.31, 0.65)mm in the normal zonule group, with statistically significant differences (all P<0.05).LT and LV in the zonular weakness group were (5.14±0.45)mm and (1.22±0.53)mm, respectively, which were larger than (4.27±0.52)mm and (0.32±0.30)mm in the normal zonule group, and the differences were statistically significant (both P<0.05).Magnitude of lens decentration and tilt in the zonular weakness were 0.34 (0.13, 0.45)mm and 6.44 (3.67, 7.32)°, respectively, which were significantly larger than 0.19 (0.12, 0.25)mm and 4.88 (3.85, 5.65)° in the normal zonule group (both P<0.05).No obvious pattern was found in the direction of decentration and tilt.Logistic regression analysis showed that LV and lens decentration were risk factors of zonular weakness (odds ratios [ OR]=706.170, 335.339; both P<0.05), and RAL was a protective factor of zonular weakness ( OR=0.239, P<0.05).

Conclusions  Age-related cataract patients with zonular weakness often present with a decrease in ACV due to increased anterior convexity of the lens.Decreased RAL, increased lens decentration and elevated LV are risk factors for zonular weakness.

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