### Evidence Report/Technology Assessment: Number 38

# Surgical Treatment of Coexisting Cataract and Glaucoma

## Summary

----

Under its Evidence-based Practice Program, the Agency for Healthcare Research and Quality (AHRQ) is developing scientific information for other agencies and organizations on which to base clinical guidelines, performance measures, and other quality improvement tools. Contractor institutions review all relevant scientific literature on assigned clinical care topics and produce evidence reports and technology assessments, conduct research on methodologies and the effectiveness of their implementation, and participate in technical assistance activities. 

Overview / Reporting the Evidence / Methodology / Findings / Future Research / Availability of the Full Report

----

## Overview

Cataract and glaucoma are both commonconditions and are often present in the samepatient. Cataract surgery is the most commonlyperformed surgical procedure on Medicarebeneficiaries. In 1998, approximately 1.4 millioncataract surgeries were performed on Medicarebeneficiaries. Primary open-angle glaucomaaffects at least 2.5 million individuals in theUnited States, predominantly adults over 50 yearsof age. The total direct cost expenditures forglaucoma therapy have been estimated at $1.56billion dollars per year.

Although guidelines exist for the indicationsfor cataract surgery in the otherwise healthy eyeand for glaucoma surgery in eyes with glaucoma,there is controversy concerning the indications forsurgery when both cataract and glaucoma arepresent. In addition, there is no clear consensusabout the appropriate timing of the surgery foreither condition, or about the best surgicaltechnique. Furthermore, there is no agreementconcerning the optimal management of thesedisorders when coexistent. Therefore, the Agencyfor Health Care Policy and Research, nowrenamed the Agency for Healthcare Research andQuality (AHRQ), awarded a contract to theJohns Hopkins University Evidence-basedPractice Center to prepare an evidence report onthe topic. This evidence report was undertaken:

- To identify the most important questions pertinentto surgical treatment of coexisting cataract andglaucoma. 
- To assess the quality and content of theevidence on surgical treatment of coexistentcataract and glaucoma.
- To inform clinicalpractitioners and identify areas where futureresearch is needed.

Return to Contents

## Reporting the Evidence

The target population addressed in thisevidence report is adult patients with coexistingcataract and glaucoma. Both open- and closed-angleglaucoma were considered. The targetaudience for the report is health care professionalsinvolved in the care of adult patients withcoexisting cataract and glaucoma.

The following questions were addressed in theevidence report:

- What are the risks and benefits of stagedversus combined procedures for coexistingcataract and glaucoma?
- What is the effect of cataract surgery onshort- and long-term intraocular pressure(IOP) control in open-angle glaucomapatients?
- What is the effect of glaucoma surgery (i.e.,filtration surgery) on the development andprogression of cataract?
- What are the risks and benefits of antifibrosisagents in the surgical treatment of coexistingcataract and glaucoma?
- What are the risks and benefits oftrabeculectomy versus endoscopic laser versusdeep sclerectomy/viscocanulostomy inpatients with coexisting cataract andglaucoma?
- What are the risks and benefits of single-siteversus two-site operations for coexistingcataract and glaucoma?
- What are the risks and benefits of nuclearexpression or phacoemulsification in patientswith coexisting cataract and glaucoma?

The interventions evaluated included twocommonly used methods for cataract extraction:nuclear expression and phacoemulsification.Several methods used for the surgicalmanagement of glaucoma were studied, includinglaser treatment, filtration surgery, and the newertechniques of endoscopic cyclophotocoagulationand the so-called nonpenetrating procedures.The use of the antifibrosis agents 5-fluorouraciland mitomycin C was also evaluated. The various ways inwhich cataract and glaucoma surgery can be performed eithersimultaneously or sequentially were studied.

The primary outcome assessed for the questions involvingglaucoma surgery was IOP, both in the immediatepostoperative period and long term. The articles reviewedgenerally lacked useful data on optic nerve appearance andvisual fields, thereby precluding a meaningful review of thoseoutcomes. Likewise, the lack of information concerningcomplications limited the ability to address the risk aspects ofeach question. For the question concerning the developmentof cataract after glaucoma surgery, both the observation of acataract and the performance of cataract surgery were assessedoutcomes.

Return to Contents

## Methodology

The literature searches were conducted using two electronicdatabases, PubMed and CENTRAL, the CochraneCollaboration's database. The textwords and medical subjectheading (MeSH) terms we used included ("cataract" and"glaucoma") and ("surgery" or "filtering surgery" or "cataractextraction" or "sclerostomy" or "trabeculectomy" or"phacoemulsification"). To retrieve the appropriate types ofstudies, we included variants of "randomized controlled trials"in the search as well as "case report" and "case series." Welimited the search to publications in English. Citationsspanned the period from 1980 to April 2000. The electronicsearches were augmented by a hand search of primary journals.

The abstracts of all identified citations were independentlyreviewed by two members of the study team to determine ifthey met eligibility criteria. When reviewing abstracts, thefollowing criteria were used to exclude articles from furtherconsideration: 

- Lack of adults in the study population.
- Lack of original data. 
- Failure to include human data. 
- Failure to address open-angle glaucoma or primary angle closure glaucoma.
- Neither a controlled trial nor a case series greater than or equalto 100 eyes.
- Addressing only intracapsular cataract surgery.
- Addressing only full-thickness procedures.

Meeting abstracts and texts not in English were also excluded. Disagreementsbetween reviewers about the eligibility of a citation wereadjudicated at a meeting of the entire study team. Wereviewed the full text of the article for a 5-percent randomsample of rejected abstracts. None of these articles wasdeemed eligible for inclusion in the full article review.

Two forms were developed and used to review eligiblecitations. The quality assessment form contained questionsgrouped into the following categories:

- Representativeness of study population-how completelythe authors described the study subjects.
- Bias and confounding, including completeness ofrandomization and masking.
- Description of therapy-completeness of the descriptionof the study protocol and other treatments, if applicable.Outcomes and followup, including explicit description ofthe outcomes reported (e.g., assessment of IOP, cataractassessment) and length of followup.
- Statistical quality and interpretation.

Quality scores for each controlled trial and cohort studywere tabulated.

The article content assessment form was developed throughan iterative process. The study team discussed whichoutcomes should be included on the form. Following thesediscussions, selected relevant articles were reviewed to create astandardized abstraction of reported outcomes in a mannerthat was applicable across the range of studies. Finally, theform was pilot tested on a sample of articles and revised asnecessary. Instructions for the use of the form were developedby consensus for the purposes of consistency.

Each article identified by the search process and determinedto meet eligibility criteria through the abstract process wasreviewed by two reviewers. At least one of the reviewers wastrained in research methodology and at least one was trainedin ophthalmology or internal medicine.

Data from the article review process were entered into arelational database. For each study question, one member ofthe analysis team summarized the available data and reached aconclusion about the answer to the question. The entire studyteam assigned an evidence grade to the conclusions reachedabout each study question.

Return to Contents

## Findings

Of 919 unique, potentially relevant citations, 131 articleswere eligible for full article review. After 21 were excluded,110 articles remained for data extraction. Study quality scoreswere calculated for controlled trials and cohort studies,comprising 81 articles. The mean overall study quality scorewas 53 percent.

The findings are as follows.

**Strongly Supported by the Literature**

- Glaucoma surgery was associated with an increased risk ofpostoperative cataract.
- A glaucoma procedure added to cataract surgery lowersIOP more than cataract surgery alone.

**Moderately Supported by the Literature**

- Limbus- and fornix-based conjunctival incisions providedthe same degree of long-term IOP lowering in combinedsurgery.
- In combined surgery using phacoemulsification, the sizeof the cataract incision did not affect long-term IOPcontrol.
- 5-fluorouracil was not beneficial in further lowering IOPwhen used with combined procedures.
- Mitomycin C was efficacious in producing lower long-termIOPs when used with combined procedures.

**Weakly Supported by the Literature**

- Combined procedures resulted in lower IOP at 24 hoursthan cataract extraction alone.
- Extracapsular cataract extraction (ECCE) alone appears toincrease IOP at 24 hours.
- In the long term, cataract surgery alone lowered IOP by 2to 4 mm Hg, combined cataract and glaucoma surgerylowered IOP by 6 to 8 mm Hg, and the performance of aglaucoma procedure alone provided even greater long-termIOP lowering than combined cataract and glaucomasurgery.
- Combined surgery in which the incisions for the cataractextraction and glaucoma procedure are separate providedslightly lower long-term IOP than a one-site approach.
- Combined surgery in which phacoemulsification is usedprovided slightly lower long-term IOP than nuclearexpression.
- The same complications occurred with combined surgeryas occur with cataract and glaucoma surgery performedseparately.
- 5-fluorouracil use was associated with epithelial defects.
- Hypotony was more likely after the use of antifibrosisagents than after surgery performed without antifibrosisagents.

Return to Contents

## Future Research

The literature addressing management of coexistent cataractand glaucoma has important limitations that future researchshould consider and address. First, those limitationspertaining to the entire literature are described, and then thosethat are specific to individual questions are described.

In terms of the management of glaucoma, because theextant literature concentrates on IOP, this review was limitedto the effect of surgery on IOP. Future studies should assessthe effect of surgery on the appearance of the optic nerve,visual field, and quality of life. Because of the chronic andslowly progressive nature of glaucoma, these parameters needto be evaluated in long-term (5 years or more) studies.

In terms of cataract, future studies should pay moreattention to the quantification of cataract and its effect onvision. The existing literature is generally lacking in anyobjective description of the ocular lens, whether clear orcataractous. Quantifying lens opacity and assessing its effecton vision and vision-related quality of life should be a priorityin future studies. Standardized grading systems for cataract(already in use) should be employed.

Although the literature represented populations in NorthAmerica, Europe, and Asia, few of the reports includedsignificant numbers of black Americans. This population hasa high prevalence of glaucoma and may respond differently toglaucoma surgery. Future researchers should strive to includemore black Americans in their studies.

Assessment of the evidence was limited by the quality of theliterature. In several of the study quality categories,particularly bias and confounding, there was tremendous roomfor improvement. A lack of comparability of study groups andan absence of masking of observers greatly compromised thevalidity of many studies. In future studies, it would bevaluable to strive for comparability of study groups andstatistical adjustment for baseline differences, as well as moreobjective measures for assessing outcomes.

The following specific questions are areas for futureresearch, both because of their importance and the fact thatquestions remain unresolved by the extant literature:

- Does trabeculectomy alone lower IOP more thanphacoemulsification plus trabeculectomy?
- Does phacoemulsification harm functioning filteringblebs?
- Does phacoemulsification reliably result in lower IOP onthe first day after surgery? If so, then it might not benecessary to perform combined surgery.
- Does a two-stage procedure provide lower IOP than acombined procedure?
- What is the role of mitomycin C in combined proceduresand how should it be administered?
- Is the finding of decreased posterior capsular opacificationwith the use of mitomycin C reproducible?
- Can better glaucoma procedures be developed to be usedin conjunction with cataract surgery?
- What are the risk factors for cataract development andprogression following glaucoma surgery?

Return to Contents

## Availability of the Full Report

The full evidence report from which this summary wasderived was prepared for the Agency for Healthcare Researchand Quality by the Johns Hopkins University Evidence-basedPractice Center under contract 290-097-0006. Printed copies can beobtained free of charge from the AHRQ PublicationsClearinghouse by calling 1-800-358-9295. Request EvidenceReport/Technology Assessment: Number 38, *SurgicalTreatment of Coexisting Cataract and Glaucoma* (AHRQPublication  No. 01-E050.

The Evidence Report can also be downloaded as a zipped file online at: www.ahrq.gov/clinic/evrptfiles.htm#cataglau.

Return to Contents

*AHRQ Publication Number 01-E049Current as of June 2001*

----

**Internet Citation:**

*Surgical Treatment of Coexisting Cataract and Glaucoma*. Summary, Evidence Report/Technology Assessment: Number 38. AHRQ Publication  No. 01-E049, June 2001. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/clinic/epcsums/catarsum.htm

----

Return EPC Evidence ReportsClinical InformationAHRQ Home PageDepartment of Health and Human Services