Elsevier

Ophthalmology

Volume 111, Issue 4, April 2004, Pages 679-685
Ophthalmology

Original article
Effect of cataract surgery on the corneal endothelium: Modern phacoemulsification compared with extracapsular cataract surgery

Presented at: United Kingdom and Ireland Society of Cataract and Refractive Surgeons meeting, September, 2002; Chester, United Kingdom.
https://doi.org/10.1016/j.ophtha.2003.07.015Get rights and content

Abstract

Purpose

To investigate whether modern phacoemulsification surgery results in more damage to the corneal endothelium than extracapsular cataract extraction (ECCE), and to examine which preoperative, operative, and postoperative factors influence the effect of cataract surgery on the endothelium.

Participants

Five hundred patients 40 years or older were randomized into 2 groups (ECCE, 249; phacoemulsification, 251).

Methods

Central corneal endothelial cell counts, coefficient of variation of cell size, and hexagonality were assessed before surgery and up to 1 year postoperatively.

Main outcome measure

Endothelial cell count.

Results

Four hundred thirty-three patients completed the trial. The initial preoperative mean cell count for the entire sample was 2481 (standard error [SE]: 18.6), reduced at 1 year postoperatively to 2239 (SE: 23.5). An average 10% reduction in cell count was recorded by 1 year postoperatively. There was no such change in hexagonality or in the coefficient of variation. There was no significant difference in overall percentage cell loss between the 2 treatment groups. Factors associated with excessive cell loss (≥15% by 1 year) were a hard cataract (odds ratio [OR]: 2.1, 95% confidence limits: 1.1–4.1; P = 0.036), age (OR: 1.04, P = 0.005), and capsule or vitreous loss at surgery (OR: 2.38, P = 0.106). Phacoemulsification carried a significantly higher risk (OR: 3.7, P = 0.045) of severe cell loss in the 45 patients with hard cataracts relative to ECCE (52.6% vs. 23.1%; chi-square test, P = 0.041), with both procedures achieving similar postoperative visual acuity outcomes.

Conclusions

No significant difference in overall corneal endothelial cell loss was found between these 2 operative techniques. The increased risk of severe cell loss with phacoemulsification in patients with hard cataracts suggests that phacoemulsification may not be the optimal procedure in these cases, and that ECCE should be preferred.

Section snippets

Materials and methods

The clinical work for this prospective study was conducted in 2 centers (Moorfields Eye Hospital, London and the Oxford Eye Hospital) over a period of 4 years (1994–1998). The randomization procedure, sample size estimation, and methodology have been described in full elsewhere,1 and hence will be described briefly. Approval was obtained from ethics committees at both centers. All consenting patients with age-related cataracts admitted for surgery at these centers were potentially eligible. The

Results

Of the 439 patients who completed the trial and had the final follow-up at 1 year postoperatively, 433 (99%) had complete data on corneal endothelial cell count before surgery and over the 1-year postoperative follow-up period. The profile of these patients is shown in Table 1. The initial preoperative mean cell count for the entire sample was 2481 (standard error [SE]: 18.6), reduced at 1 year postoperatively to 2239 (SE: 23.5). Figure 1 depicts the change in cell count over the follow-up

Demographics and study design

The design of this study had several important strengths. The study design (randomized controlled trial) and the large number of subjects (relative to other studies) recruited with similar numbers in each of the treatment groups lend considerable statistical power to the findings. These factors, in addition to high response rates at follow-up periods, have been noted to be important in such endothelial cell studies comparing cataract surgery techniques, where it is important to identify the

Acknowledgements

The authors are grateful for the input of Moorfields Eye Hospital NHS Trust, The Oxford Eye Hospital NHS Trust, and the Southampton Universities Hospitals Trust. In particular, they thank the ophthalmologists Professor T. Bron, Hung Cheng, L. Ficker, S. Tuft, J. Stevens, E. Craig, T. Gray, R. Aggarwal, A. Steele, R. Daniel, and Sister J. Morrin. The authors also thank K. Buckingham and J. Roberts for advice on economic methods, and Isabel Moldon and Lynda Lindsell, who managed the trial at the

References (34)

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This study was funded by a project grant from the Medical Research Council, United Kingdom. Allergan, Alcon, and Bausch & Lomb donated intraocular lenses and materials.

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