Elsevier

Ophthalmology

Volume 121, Issue 9, September 2014, Pages 1699-1705
Ophthalmology

Original article
Longitudinal Changes of Angle Configuration in Primary Angle-Closure Suspects: The Zhongshan Angle-Closure Prevention Trial

https://doi.org/10.1016/j.ophtha.2014.03.039Get rights and content

Objective

To determine longitudinal changes in angle configuration in the eyes of primary angle-closure suspects (PACS) treated by laser peripheral iridotomy (LPI) and in untreated fellow eyes.

Design

Longitudinal cohort study.

Participants

Primary angle-closure suspects aged 50 to 70 years were enrolled in a randomized, controlled clinical trial.

Methods

Each participant was treated by LPI in 1 randomly selected eye, with the fellow eye serving as a control. Angle width was assessed in a masked fashion using gonioscopy and anterior segment optical coherence tomography (AS-OCT) before and at 2 weeks, 6 months, and 18 months after LPI.

Main Outcome Measures

Angle width in degrees was calculated from Shaffer grades assessed under static gonioscopy. Angle configuration was also evaluated using angle opening distance (AOD250, AOD500, AOD750), trabecular-iris space area (TISA500, TISA750), and angle recess area (ARA) measured in AS-OCT images.

Results

No significant difference was found in baseline measures of angle configuration between treated and untreated eyes. At 2 weeks after LPI, the drainage angle on gonioscopy widened from a mean of 13.5° at baseline to a mean of 25.7° in treated eyes, which was also confirmed by significant increases in all AS-OCT angle width measures (P<0.001 for all variables). Between 2 weeks and 18 months after LPI, a significant decrease in angle width was observed over time in treated eyes (P<0.001 for all variables), although the change over the first 5.5 months was not statistically significant for angle width measured under gonioscopy (P = 0.18), AOD250 (P = 0.167) and ARA (P = 0.83). In untreated eyes, angle width consistently decreased across all follow-up visits after LPI, with a more rapid longitudinal decrease compared with treated eyes (P values for all variables ≤0.003). The annual rate of change in angle width was equivalent to 1.2°/year (95% confidence interval [CI], 0.8–1.6) in treated eyes and 1.6°/year (95% CI, 1.3–2.0) in untreated eyes (P<0.001).

Conclusions

Angle width of treated eyes increased markedly after LPI, remained stable for 6 months, and then decreased significantly by 18 months after LPI. Untreated eyes experienced a more consistent and rapid decrease in angle width over the same time period.

Section snippets

Methods

Ethical approval was obtained from the Ethical Review Board of Sun Yat-sen University and the Ethical Committee of Zhongshan Ophthalmic Center. The study also received institutional review board approval from Moorfields Eye Hospital (via the London School of Hygiene and Tropical Medicine) and Johns Hopkins University Hospital. The study was conducted in accordance with the Tenets of the World Medical Association's Declaration of Helsinki. Study participants were recruited from a randomized

Results

A total of 775 participants (135 men and 640 women; age (mean ± standard deviation): 59.4±5.0 years) with data available from all follow-up visits up to 18 months after LPI were included in the current analysis. When comparing eyes treated by LPI with untreated eyes, no significant difference was found in baseline features before LPI, including angle width assessed under static gonioscopy, AS-OCT measures (i.e., AOD250, AOD500, AOD750, TISA500, TISA750, and ARA), limbal anterior chamber depth,

Discussion

In this study of longitudinal changes of angle configuration in angle-closure suspects, we observed an overall trend of significant narrowing of the anterior chamber angle over time in both treated and untreated eyes after LPI. The magnitude of decrease in angle width over time was significantly more pronounced in eyes without any intervention. Apart from the increase in angle width due to the elimination of pupillary block, which is an apparent benefit from LPI, the change of angle width after

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    Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

    Supported by Fight for Sight (grant no. 1655) (United Kingdom) and the Sun Yat-sen University 5010 Project Fund (grant no. 2007033) (China). Y.J. receives additional support from the British Council for Prevention of Blindness PhD Scholarship and UCL Overseas Research Scholarship. A.P.K. is supported by a Wellcome Trust Clinical Research Fellowship (grant no. 094791/Z/10/Z). P.J.F. receives additional support from the NIHR Biomedical Research Centre at Moorfields Eye Hospital, London, United Kingdom (NIHR-BRC2 009; Moorfields/UCL-IOO), and the Richard Desmond Charitable Foundation (via Fight for Sight UK). The sponsors or funding organizations had no roles in the design or conduct of this research.

    ∗

    M.H., D.S.F., and P.J.F. contributed equally to this work.

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