[Ocular biometry of infants and young children with congenital cataract]

Objective: To understand the developmental characteristics of early ocular biological parameters in patients with congenital cataract. Methods: Retrospective case series study. The ocular biometry data such as the axial length, corneal curvature, anterior chamber depth and central corneal thickness of 169 patients under 3 years old who were diagnosed with congenital cataract in Eye Hospital of Wenzhou Medical University (Hangzhou Branch) from June 2016 to June 2020 were reviewed, and they were analyzed by 3 age groups. There were 87, 41, and 41 patients in three age groups, 1 to 6 months, 7 to 12 months, and 13 to 36 months, respectively; 108 patients with bilateral affected eyes and 61 patients with unilateral affected eyes were included; 84 patients with partial opacity lens and 85 patients with total opacity lens were included. The right eyes of the patients with bilateral congenital cataract were selected for analysis. Statistical analysis of ocular biological parameters between groups was performed using the independent samples t-test and paired samples t-test. Statistical analysis of the relationship between age in months and biological parameters was performed using the Pearson's correlation test. Results: The axial length at the age of 1 to 6 months in the affected eyes of patients with bilateral cataract was (17.59±1.19) mm, it was shorter than the affected eyes of patients with unilateral cataract [(18.18±1.34) mm], and the axial length in the affected eyes of patients with unilateral cataract were shorter than the healthy eyes [(19.01±0.93) mm]. At the age of 7 to 12 months, the axial length in the affected eyes of patients with unilateral cataract [(19.89±0.74) mm] was shorter than the healthy eyes [(20.48±0.43) mm]. The differences were statistically significant (t=-2.06, -5.62, -3.47, all P<0.05). The axial length in the affected eyes with partial opacity at the age of 1 to 6 months was shorter than those with total opacity [(17.43±1.14) mm vs. (18.06±1.29) mm; t=-2.38, P=0.020]. The difference in axial length (affected eyes vs. healthy eyes) was significantly correlated with the age in months in partial cataract (r=0.53, P=0.001). The corneal curvature in the affected eyes of patients with unilateral cataract was flatter than the healthy eyes at the age of 7 to 12 months [(42.41±1.82) D vs. (43.19±1.96) D; t=-2.29, P=0.038], but was steeper at the age of 13 to 36 months [(43.36±2.32) D vs. (42.55±1.88) D; t=2.17, P=0.043]. The anterior chamber depth in the affected eyes of patients with unilateral cataract was less than the healthy eyes at the age of 1 to 6 months [(2.44±0.37) mm vs. (2.58±0.33) mm; t=-2.08, P=0.048].The central corneal thickness in the affected eyes of patients with unilateral cataract was thicker than the healthy eyes both at the age of 1 to 6 months and 7 to 12 months [(555.26±46.95) μm vs. (541.85±40.78) μm, (542.93±27.63) μm vs. (530.93±30.36) μm; t=3.82, 2.26; P=0.001, 0.040]. Conclusions: Congenital cataracts maybe affect the early development of axial length, corneal curvature, anterior chamber depth and central corneal thickness. The degree of lens opacity maybe affecte the early axial length development. The axial length in eyes with partial opacity can be shorter than those with total opacity before the age of 6 months, and thereafter gradually outnumbered the latter.

[Comparison of the accuracy of intraocular lens power calculation formulas based on the new swept-source optical coherence tomography biometry]

Objective: To compare the accuracy of 6 intraocular lens power calculation formulas based on the new swept-source optical coherence tomography biometry and to analyze the prediction error. Methods: Retrospective case series study. Clinical data were collected from 599 patients (599 eyes) who had underwent uncomplicated phacoemulsification and the IOLMaster 700 examination at the Eye Hospital of Wenzhou Medical University between November 2018 and November 2019. Among the patients, there were 208 males and 391 females with an age of (69±10) years. According to the axial length (AL), eyes were divided into the short AL group (≤22.5 mm, n=100), the normal AL group (>22.5 mm and<25.5 mm, n=375); and the long AL group (≥25.5 mm, n=124). Eyes were also grouped based on the mean keratometry (Km) as flat (≤42.00 D, n=47), normal (>42.00 D to<46.00 D, n=461), and steep (≥46.00 D, n=91), and by anterior chamber depth (ACD) as shallow (≤2.5 mm, n=71), normal (>2.5 mm to<3.5 mm, n=436), and deep (≥3.5 mm, n=92). The median absolute errors (MedAEs) of the Barrett Universal Ⅱ, Haigis, Hoffer Q, Holladay Ⅰ, Holladay Ⅱ, and SRK/T formulas in different AL, Km, and ACD groups were compared using the Friedman test. Results: The differences in MedAE among the 6 formulas of 599 patients (599 eyes) were statistically significant (χ²=120.549, P<0.001). The MedAE of the Barrett Universal Ⅱ formula was smallest (0.35 D), followed by the SRK/T formula (0.36 D). There was no significant difference between the MedAEs of the Barrett universal Ⅱ and Haigis, SRK/T formula (all P=1.000), but there were statistically significant differences among the other formulas (all P<0.01). In different AL groups, the MedAE of each formula was statistically different (χ²=38.307, 38.779, 112.997; all P<0.01).The Barrett Universal Ⅱ formula resulted in the lowest MedAE in the short AL group (0.40 D) and the long AL group (0.31 D). The MedAE of the SRK/T in the normal AL group was lowest (0.35 D). The 6 formulas showed significant differences in MedAE values in different Km groups (χ²=12.284, 90.924, 39.387; all P<0.05).The Haigis formula achieved the lowest MedAE in the flat Km group (0.26 D) and the steep Km group (0.34 D). The Barrett UniversalⅡ formula achieved the lowest MedAE in the normal Km group (0.33 D). The differences in MedAE values of the 6 formulas in different ACD groups were statistically significant (χ²=37.389, 57.643, 52.845; all P<0.01), and the MedAE values of the Barrett Universal Ⅱ in different ACD groups were smallest (0.46, 0.33, 0.31 D). Conclusions: The Barrett Universal Ⅱ formula perform the best over the entire AL range, followed by the Haigis and SRK/T formulas. The Barrett Universal Ⅱ formula result in the lowest prediction error in the short AL group, the long AL group, and all ACD groups. The Haigis formula may be more accurate when the Km was ≤42.00 D or ≥46.00 D. (Chin J Ophthalmol, 2021, 57: 502-511).

[Dynamic changes of axial length, corneal refractive power, and refractive state after cataract surgery in infants]

Objective: To investigate the changes of axial length, corneal refractive power, and refractive state in infants with congenital cataract surgery. Methods: Retrospective cohort study. Medical records of 103 patients who underwent congenital cataract surgery in the Eye Hospital of Wenzhou Medical University Hangzhou Branch from January 1, 2015 to December 31, 2018 were reviewed. There were 61 boys and 42 girls in the study. The mean age at the surgery of 103 congenital cataract patients was (3.95±1.94) months. In patients receiving bilateral cataract surgery, only the left eye was selected for analysis. The patients were followed up for at least 1 year. The patients were divided into the groups of <4 months old and 4-12 months old according to the age at cataract surgery. The change in the axial length, corneal refractive power, and refractive state of each patient at 1 year after surgery was analyzed. Independent sample t-test, one way variance analysis and simple linear regression were used for statistical analysis. Results: There were 71 cases of bilateral cataract, including 33 in the group of <4 months old and 38 in the group of 4-12 months old, and 32 cases of unilateral cataract, including 17 in the group of <4 months old and 15 in the group of 4-12 months old. The change in the axial length of bilateral cataract children in the <4-month-old group was (2.46±1.33) mm at 1 year after surgery, which was greater than (1.52± 1.00) mm in the group of 4-12 months old (t=3.21; P<0.01). In the same surgery age group, there was no significant difference in the change of axial length among bilateral cataract eyes, unilateral cataract eyes and the contralateral eyes at 1 year after surgery (both P>0.05). One year after surgery, the axial length of the eyes in patients with bilateral cataract, the affected eyes and the fellow eyes in patients with unilateral cataract all was highly correlated with the logarithm of the actual age (r=0.68, 0.52, 0.73; all P<0.01). The corneal refractive power showed a decreased trend with the increase of age. The change in the corneal refractive power of the bilateral cataract children in the <4-month-old group at 1 year after surgery was (1.43±2.87) D, and in the group of 4-12 months old was (0.68±2.10) D, but the difference was not statistically significant (P>0.05). The chang in spherical equivalent of bilateral cataract children was (2.02±2.60) D in the <4-month-old group, greater than that in the group of 4-12 months old [(0.69±1.89) D; t=2.15; P<0.05]. The change of spherical equivalent one year after surgery in 4-12 months group, unilateral cataract eyes was significantly greater than that of bilateral cataract eyes [(2.05±0.95) D vs. (0.69±1.89) D; t=2.49; P<0.05]. The spherical equivalent of both bilateral and unilateral cataract children was highly correlated with the actual age (r=-0.51, -0.54; both P<0.01). Conclusions: The axial length is increased, the corneal refractive power is decreased, and the spherical equivalent is decreased at 1 year after surgery for congenital cataract in infants. The younger the age at cataract surgery, the greater the change in the axial length, myopia drift, and corneal refractive power. (Chin J Ophthalmol, 2021, 57: 34-40).