CLINICAL SCIENCES Effect of Cataract Extraction on the Visual Fields of Patients With Glaucoma Monica M. Carrillo, MD; Paul H. Artes, PhD; Marcelo T. Nicolela, MD; Raymond P. LeBlanc, MD; Balwantray C. Chauhan, PhD Objective: To investigate the effect of cataract extrac- the effect and control analyses was less than 0.1 dB and tion on the visual fields of patients with open-angle not statistically significant (P=.85). There was a strong glaucoma. correlation between change in foveal sensitivity and change in mean deviation in the effect analysis but not Methods: Patients in a prospective cohort study in a ter- in the control analysis (r=0.76 [PϽ.001] and r=0.30 tiary center underwent standard automated perimetry ev- [P=.08], respectively). There was no relationship be- ery 6 months. We compared the mean results of the 2 tween change in visual acuity or initial mean deviation examinations immediately before and 2 examinations im- and change in mean deviation in either analysis. Change mediately after phacoemulsification cataract extraction in pointwise total deviation was not systematically re- and intraocular lens implant (effect analysis) and the mean lated to the respective baseline value in either analysis; results of the first 2 and last 2 examinations from 4 con- however, the variance of the distribution of change in total secutive examinations obtained more than 1 year after deviation was significantly higher in the effect analysis the cataract surgery (control analysis). (PϽ.001). Results: Our sample contained 34 eyes of 26 patients Conclusion: While there was an improvement in best- (mean±SD age, 69.2±10.8 years). While the mean log- corrected visual acuity after cataract surgery, the changes MAR best-corrected visual acuity improved signifi- in the visual field as a group were negligible. cantly by approximately 2 Snellen lines after surgery (PϽ.001), the average change in mean deviation in both Arch Ophthalmol. 2005;123:929-932 TATIC AUTOMATED PERIMETRY seen in glaucoma is unlikely to be related is a well-established and to cataract.2,5 essential tool in the diagno- The effect of cataract surgery on the vi- sis and long-term manage- sual field has been studied previously in ment of glaucoma. The healthy subjects and glaucoma patients us- Sdevelopment of cataract in patients with ing manual6 and automated7-10 perim- glaucoma may exacerbate the visual field etry. In studies with glaucoma patients, loss and may make it difficult to distin- there was a range of visual field damage guish between visual field changes due to and the density of cataract, and while most cataract and those due to the progression studies found an increase in visual field of glaucoma. sensitivity after cataract surgery, there is Cataracts are thought to cause visual considerable variance in the results, with degradation by 3 mechanisms: image some studies showing a meaningful effect7 blur, light scattering, and decreased illu- and others showing a modest or no effect.10 mination.1 Investigation of the effect of In this study, we report the effect of cataract or light scattering (simulated cataract extraction on a group of glau- cataract) on the visual field has generally coma patients followed up in a longitudi- shown that cataract results in diffuse nal prospective study. In contrast to other reduction of sensitivity in healthy sub- studies, we computed a mean of 2 fields Author Affiliations: 2-5 Department of Ophthalmology jects. Although the pattern of sensitiv- before and after surgery and used a paired and Visual Sciences, Dalhousie ity loss may not be entirely uniform control analysis in the same eyes to cor- University, Halifax, Nova Scotia. across the visual field, predominantly rect for any possible regression to the mean Financial Disclosure: None. localized field loss such as that frequently effect and visual field progression. (REPRINTED) ARCH OPHTHALMOL / VOL 123, JULY 2005 WWW.ARCHOPHTHALMOL.COM 929 ©2005 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/24/2021 Informed consent was obtained from all subjects, and the te- A B nets of the Declaration of Helsinki were followed. 0.5 In the effect analysis, we compared the mean results of the 2 visual fields immediately before and immediately after sur- 0.4 gery. In the control analysis, the mean results of the first 2 and 0.3 last 2 field examinations from 4 consecutive examinations ob- 0.2 tained more than 1 year after surgery were compared. In this 0.1 case, the first 2 fields constituted the equivalent of the presur- gery fields and the latter 2 the postsurgery fields. Visual field 0 data were averaged by computing the mean pointwise total de- Postsurgery Visual Acuity, logMAR Postsurgery Visual Acuity, viation (TD). The visual acuity data were averaged correspond- –0.1 0 0.1 0.2 0.3 0.4 0.5 –0.1 0 0.1 0.2 0.3 0.4 0.5 Presurgery Visual Acuity, logMAR ing to the dates of the visual field examinations. We examined pointwise and global changes in TD stratified according to the respective baseline values. The mean and standard deviation Figure 1. Change in visual acuity in the effect (A) and control (B) analyses. of TD yielded the unweighted MD and pattern standard devia- The diagonal line indicates equal values before and after surgery. tion indexes, respectively. To study the influence of visual field eccentricity on pointwise TD, the visual field was divided into 2 zones: zone 1, stimuli within 16° eccentricity; and zone 2, A B 0 stimuli outside 16° eccentricity. To study the effect of baseline pointwise TD on the change in TD in the effect and control analy- –5 ses, the data were binned across all patients in 5-dB steps cen- –10 tered on −30 dB, −25 dB, and so on. The presurgery and postsurgery data were compared using –15 either a paired t test or a Wilcoxon matched-pairs signed rank test. PϽ.05 was considered statistically significant. –20 Mean Deviation After Surgery, dB Mean Deviation After Surgery, –25 –20 –15 –10 –5 0 –25 –20 –15 –10 –5 0 RESULTS Mean Deviation Before Surgery, dB Figure 2. Change in mean deviation in the effect (A) and control (B) Thirty-four eyes of 26 patients (mean±SD age, 69.2±10.8 analyses. The diagonal line indicates equal values before and after surgery. years) were included in the study. In the effect analysis, the mean±SD time between the first visual field exami- nation before surgery and the last visual field examina- METHODS tion after surgery was 19.9±6.8 months, while that in the control analysis was 17.3±6.6 months. Data for this study were obtained from a longitudinal prospec- Thirty (88%) of the 34 eyes underwent phacoemul- tive study that began in September 1991, in which various psy- sification cataract surgery with intraocular lens implan- chophysical tests and scanning laser tomography were per- tation, while 4 (12%) underwent combined phacoemul- formed in a group of patients with open-angle glaucoma. Patients sification cataract surgery with intraocular lens were recruited consecutively from the practice of one of us (R.P.L.) and the Glaucoma Clinic of the Eye Care Centre of the implantation and trabeculectomy. Queen Elizabeth II Health Science Centre, Halifax. The mean logMAR best-corrected visual acuity Inclusion criteria were as follows: (1) best-corrected visual improved significantly (PϽ.001) from a mean of 0.24 acuity of at least 6/12; (2) diagnosis of open-angle glaucoma (range, 0.00-0.48) to 0.07 (range, 0.00-0.33), or with glaucomatous optic disc damage, such as notching or pro- approximately 2 Snellen lines of visual acuity, after sur- gressive thinning of the neuroretinal rim and visual field dam- gery (Figure 1A). Two (6%) of the eyes had a poorer age with an initial mean deviation (MD) between −2 and −10 postsurgical visual acuity. One of these eyes developed dB; (3) open angles by gonioscopy; and (4) willingness to par- cystoid macular edema after surgery, which subse- ticipate in the study and to give informed consent. Exclusion quently resolved. In the control analysis, the change in criteria were as follows: (1) concomitant chronic ocular dis- visual acuity was not statistically significant (from 0.06 ease, (2) refractive error exceeding 5 diopters (D) spherical equivalent or3Dofastigmatism, (3) aphakia, (4) systemic dis- [range, −0.06 to 0.30] to 0.09 [range, −0.06 to 0.33], ease or systemic medication known to affect the visual field or P=.08) (Figure 1B). ability to participate in the study, (5) chronic ocular medica- In the effect analysis, there was no significant change tion other than for glaucoma, and (6) contact lens wear. All in MD (mean±SD from −6.74±3.75 to −6.68±3.96 dB, eyes included in this study underwent phacoemulsification cata- P=.85) (Figure 2A). In the control analysis, the change ract extraction and intraocular lens implantation alone or in in MD was almost identical (mean±SD from −6.46±4.15 combination with trabeculectomy, and had at least 2 visual field to −6.38±4.19 dB, P=.67) (Figure 2B). There were also results available within 1 year before surgery and at least 6 vi- no significant changes in pattern standard deviation in sual field results available after surgery. Visual field examina- either the effect or control analyses (mean±SD from tions were performed with static automated perimetry using 4.40±2.52 to 4.52±2.51 dB [P=.42] and from 4.43±2.58 either the 30-2 or 24-2 full-threshold algorithm (Humphrey Field Analyzer; Carl Zeiss Meditech, Dublin, Calif) every 6 months to 4.57±2.51 dB [P=.24], respectively).