Analysis of Axial Length in Young Patients with Marfan Syndrome and Bilateral Ectopia Lentis by Z-Scores

Abstract

<b><i>Introduction:</i></b> Marfan syndrome (MFS) is characterized by ectopia lentis (EL) and elongated axial length (AL). The characteristics of AL in young patients with MFS and bilateral EL before the lens surgery are not fully understood. <b><i>Methods:</i></b> This study reviewed MFS patients under 20 years old with bilateral EL from January 2015 to October 2020. The Z-scores were introduced in terms of the number of standard deviations from the mean of age-matched normative data. Using Z-scores, the distribution of AL and influence factors were evaluated. The correlations between AL and other biometrics were analyzed. <b><i>Results:</i></b> We reviewed 183 patients and enrolled both eyes. The mean age was 8.44 ± 4.69 years. About 36% of the patients were children under 6 years old. The median AL increased from 23.16 mm under 5 years old to 26.20 mm in the 16–20 age group, and when plotted, the trend presented a logarithmic curvature (<i>R</i><sup>2</sup> = 0.145, <i>p</i> < 0.001). The median Z-AL score was 1.24. One-third of eyes had Z-score <0. About 20% of the patients had AL difference over 1 mm between the right and left eyes, and the right one had longer Z-AL scores (<i>p</i> = 0.013). The eye complicated with megalocornea (10, 7.04%) had larger Z-AL scores (4.72 ± 3.51 vs. 1.10 ± 2.25, <i>p</i> = 0.002). A positive correlation was found between Z-AL and Z-corneal curvature radius (<i>r</i> = 0.265, <i>p</i> < 0.001). <b><i>Conclusion:</i></b> Young patients with bilateral EL but small AL should not be excluded from MFS without systematic examination. The age-adjusted Z-score will facilitate further study of the individual variations in AL across different ages.

What Should We Pay More Attention to Marfan Syndrome Expecting Ectopia Lentis: Incidence and Risk Factors of Retinal Manifestations

“…In MFS, the sclera is very thin and collapsible, with loss of elasticity and stretching leading to long AL and posterior segment lesions [ 13 ]. The misfolded FBN1 and the disorganized elastin in the scleral stroma could lead to stretching of the sclera through the two physiological functions of fibrillin-1 (structure component or TGF-β signaling mediator) and by different underlying genetic mechanisms (haploinsufficiency or dominant-negative effect) [ 22 ].…”

“…The Shapiro–Wilk test was used to confirm whether the variables followed normal distributions. The Z-scores of AL was calculated via the following formula: Z-score = (measured parameter—normative parameter)/normative standard deviation [ 22 ]. Demographic and ocular characteristics were compared across groups using the Wilcoxon rank-sun test (Mann–Whitney test), Kruskal–Wallis test, Student’ s t -test and Chi-square test.…”

Biallelic ADAMTSL4 variants in a Chinese cohort of congenital ectopia lentis: Implications for genotype–phenotype relationships

“…There seems to be a higher incidence of glaucoma, longer eye globes, and flatter corneas in probands with one or more truncation variants, although the differences did not reach significance. Besides genetic background, the axial length and cornea features in patients with EL are also complicated by other factors, such as age, sex, and laterality (Z. X. Chen, Chen, Zhang, Chen, Zheng, et al, 2021; Zhang et al, 2017). In all, these findings suggest that the more deleterious variants of ADAMTSL4 contribute to more severe ocular involvements.…”

Genotype-phenotype correlations of marfan syndrome and related fibrillinopathies: Phenomenon and molecular relevance

“…Increased AL was associated with myopia and risks for retinal detachment in patients with MFS ( Fan et al, 2014 ), which has been listed as a minor criterion in Ghent 1 nosology ( De Paepe et al, 1996 ). However, the AL of MFS has considerable individual variations, with short AL in about 30% of MFS patients in a full age range ( Drolsum et al, 2015 ; Chen et al, 2021b ). Chen et al showed that variants in the C-terminus (exons 43–65), especially the TGF-β regulating region (exons 44–49), were associated with longer AL ( Chen et al, 2021a ).…”

“…As a special form of EL, microspherophakia is characterized by the globular laxity of the zonules and the lens growth of which is arrested by insufficient mechanical stretching (Kumar et al, 2019). Microspherophakia was found in about 10% of patients with MFS and the surgical management of which is different from other types of EL (Chen et al, 2021b;Chen et al, 2022). Chen et al revealed that variants in exons 22-42, especially exon 26, had higher risks of combined microspherophakia in patients with MFS (Chen et al, 2021c).…”