Effects of Cataract Extraction on the Outcomes of Automated Perimetry and Retinal Nerve Fiber Layer Thickness Measurements by Optical Coherence Tomography in Primary Angle Closure Glaucoma

Xiaofei Man,Noel Cy Chan,Tiffany Ws Lau,Clement C Tham

doi:10.4172/2155-9570.1000623

Abstract

Objective: To evaluate the effect of cataract extraction on both visual field and retinal nerve fiber layer thickness measurements in primary angle closure glaucoma (PACG) eyes.Methods: Retrospective cohort study on 30 PACG eyes underwent cataract extraction. Changes in RNFL thickness and visual field parameters including mean deviation (MD), visual field index (VFI) and pattern standard deviation (PSD) were analyzed within 6 months before and after cataract extraction.Results: Overall, MD (p=0.003) and VFI (p=0.004) improved significantly after cataract extraction, whereas PSD showed no significant change (p=0.6). In the 10 eyes with MD worse than -20 dB, mean MD improved by 3.4 ± 3.56 dB (from -24.36 ± 3.06 dB to -20.96 ± 5.06 dB, p=0.01) and mean VFI improved by 16.25 ± 15.66% (from 23.38 ± 9.65% to 39.63 ± 20.83%, p=0.02). PSD showed no significant change after cataract extraction (p=0.07). In the 20 eyes with MD better than -20 dB, MD and VFI also improved postoperatively, but the changes did not reach statistical significance: mean MD improved by 1.64 ± 3.65 dB (from -11.57 ± 5.57 dB to -9.92 ± 5.36 dB, p=0.05) whilst mean VFI improved by 4.57 ± 12.29% (from 74.95 ± 17.95% to 79.52 ± 17.26%, p=0.07). RNFL thickness did not show any significant changes after cataract extraction (p=0.13).Conclusions: Both MD and VFI improved after cataract extraction, especially in eyes with pre-operative MD worse than -20 dB. PSD and RNFL thickness showed no significant change after cataract extraction.

Highlights

In primary angle-closure glaucoma (PACG), iridotrabecular contact developing from predisposing anterior segment anatomy, blocks the outflow of aqueous humor, potentially leads to elevated intraocular pressure (IOP) and progressive irreversible optic neuropathy
We analyzed the effect of cataract extraction on visual field and retinal nerve fiber layer (RNFL) thickness in patients with primary angle closure glaucoma (PACG) and co-existing cataract
We found that mean deviation (MD) and visual field index (VFI) on 24-2 Swedish Interactive Thresholding Algorithm (SITA) standard perimetry improved significantly after cataract extraction, especially in eyes with MD worse than -20 dB, whereas pattern standard deviation (PSD) showed no significant change

Summary

Introduction

In primary angle-closure glaucoma (PACG), iridotrabecular contact developing from predisposing anterior segment anatomy, blocks the outflow of aqueous humor, potentially leads to elevated intraocular pressure (IOP) and progressive irreversible optic neuropathy. The evaluation of glaucoma progression is highly dependent on perimetric visual field (VF) assessment and retinal nerve fiber layer (RNFL) thickness measurements by optical coherence tomography (OCT). Cataract extraction has been considered as one of the treatments for PACG in patients with co-existing cataract [4,5], which might affect the assessment of visual field and retinal nerve fiber layer (RNFL) thickness, functional and structural assessment of glaucoma progression. As most PACG subjects are more advanced in age and are more prone to receive cataract extraction during their follow-up duration, evaluating visual field and RNFL progression in glaucomatous eyes following cataract extraction is a common challenge. There has been no study reported that analyzed the effect of cataract extraction on visual field and RNFL thickness measurements in PACG patients

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