Elsevier

Ophthalmology

Volume 118, Issue 3, March 2011, Pages 474-479
Ophthalmology

Original article
Lens Vault, Thickness, and Position in Chinese Subjects with Angle Closure

https://doi.org/10.1016/j.ophtha.2010.07.025Get rights and content

Purpose

To investigate the association of lens parameters—specifically, lens vault (LV), lens thickness (LT), and lens position (LP)—with angle closure.

Design

Prospective, comparative study.

Participants

One hundred two Chinese subjects with angle closure (consisting of primary angle closure, primary angle-closure glaucoma, and previous acute primary angle closure) attending a glaucoma clinic and 176 normal Chinese subjects with open angles and no evidence of glaucoma recruited from an ongoing population-based cross-sectional study.

Methods

All participants underwent gonioscopy and anterior-segment optical coherence tomography (AS OCT; Carl Zeiss Meditec, Dublin, CA). Customized software was used to measure LV, defined as the perpendicular distance between the anterior pole of the crystalline lens and the horizontal line joining the 2 scleral spurs, on horizontal AS OCT scans. A-scan biometry (US-800; Nidek Co, Ltd, Tokyo, Japan) was used to measures LT and to calculate LP (defined as anterior chamber depth [ACD] +1/2 LT) and relative LP (RLP; defined as LP/axial length [AL]).

Main Outcome Measures

Lens parameters and angle closure.

Results

Significant differences between angle-closure and normal eyes were found for LV (901±265 vs. 316±272 μm; P<0.001), LT (4.20±0.92 vs. 3.90±0.73 mm; P = 0.01), LT-to-AL ratio (0.18±0.04 vs. 0.16±0.03; P<0.001), ACD (2.66±0.37 vs. 2.95±0.37 mm; P<0.001), and AL (22.86±0.93 vs. 23.92±1.37 mm; P<0.001), but no significant differences were found for LP (4.76±0.51 vs. 4.90±0.54 mm; P = 0.34) or RLP (0.21±0.02 vs. 0.20±0.02; P = 0.14). After adjusting for age, gender, ACD, LT, and RLP, increased LV was associated significantly with angle closure (odds ratio [OR], 48.1; 95% confidence interval [CI], 12.8–181.3, comparing lowest to highest quartile), but no association was found for LT (OR, 1.78; 95% CI, 0.76–4.16), LP (OR, 1.94; 95% CI, 0.59–6.31), or RLP (OR, 2.08; 95% CI, 0.66–6.57). There was low correlation between LV and LT (Pearson's correlation coefficient [PCC], 0.17), between LV and RLP (PCC, 0.08), or between LV and LP (PCC, 0.2).

Conclusions

Eyes with angle closure have thicker lenses with greater LV compared with normal eyes. The LV, which represents the anterior portion of the lens, is a novel parameter independently associated with angle closure after adjusting for age, gender, ACD, and LT.

Financial Disclosure(s)

Proprietary or commercial disclosure may be found after the references.

Section snippets

Patients and Methods

This was a prospective, comparative study of Chinese subjects with angle closure attending a glaucoma clinic and of normal control subjects recruited from an ongoing population-based study.11 Written informed consent was obtained from all subjects, and the study had the approval of the Institutional Review Board of Singapore Eye Research Institute and was performed in accordance with the tenets of the Declaration of Helsinki.

A case of angle closure was defined as primary angle closure (PAC),

Results

A total of 102 angle-closure subjects (consisting of 29 PAC, 53 PACG, and 20 previous APAC subjects) and 176 normal control subjects were recruited for the study. All subjects were of Chinese ethnicity. Angle-closure subjects were older (65.3±9.1 years vs. 54.2±7.9 years; P<0.001), and there were proportionately more females (66.7% vs. 46.6%; P = 0.001) compared with normals. For the normal control group, LV increased significantly with advancing age (P<0.001, for trend; Table 1, available at //aaojournal.org

Discussion

As far as the authors are aware, this is the first study to describe the LV as a unique and possibly independent ocular parameter associated with angle closure. This supports the concept that increased thickness and bulk of the lens anterior to the plane of the scleral spur pushes the peripheral iris against the trabecular meshwork, worsening angle crowding in an already predisposed eye. Increased LV likely increases the amount of iridolenticular contact, leading to a more pronounced iris

References (24)

  • A. Tomlinson et al.

    Ocular dimensions in the heredity of angle-closure glaucoma

    Br J Ophthalmol

    (1973)
  • R.F. Lowe

    Aetiology of the anatomical basis for primary angle-closure glaucoma: biometrical comparisons between normal eyes and eyes with primary angle-closure glaucoma

    Br J Ophthalmol

    (1970)
  • Cited by (289)

    View all citing articles on Scopus

    Manuscript no. 2010-268.

    Financial Disclosure(s): The author(s) have made the following disclosure(s):

    Tin Aung - Financial Support - Carl Zeiss Meditec

    Tien Yin Wong - Financial Support - Carl Zeiss Meditec

    David S. Friedman and Scott D. Smith - Instrument Loan - Carl Zeiss Meditec

    Supported by Singhealth, Singapore, Republic of Singapore; National Medical Research Council, Singapore, Republic of Singapore; and the National Research Foundation, Singapore, Republic of Singapore.

    View full text