Beta radiation for glaucoma surgery

Methodological quality of the review: High confidence

Author: Kirwan JF, Rennie C, Evans JR

Geographical coverage: Not reported

Sector: Glaucoma

Sub-sector: Beta radiation for glaucoma surgery

Equity focus: None specified

Review type: Effectiveness review

Quantitative synthesis method: Narrative/thematic synthesis

Qualitative synthesis method: Not applicable

Background: Glaucoma surgery (trabeculectomy or Trab) outcomes can be affected by the time it takes for surgical wounds to heal. A rapid, simple treatment to slow down the rate of the healing process has been proposed using beta radiation for Trab.

Objectives: The objective of this review was to assess the effectiveness of beta radiation during Trab.

Main findings: The authors of the review identified four trials that randomised 551 people to Trab with beta irradiation compared to those that underwent Trab alone. Two of the trials were in Caucasian populations, one in black African population and one in Chinese population. This review concluded that patients that underwent Trab with beta irradiation versus those that underwent Trab alone were less likely to develop high eye pressure one year after the surgery. However, it was also noted that beta irradiation was associated with a higher risk of the occurrence of cataract.

It was mentioned in the review that although beta irradiation augmented Trab and has been observed to reduce the risk of surgical failure, it is still unknown how it compares in effectiveness and safety versus other anti-metabolites that are widely used. Authors noted that this was mainly due to limited data on adverse effects. Also, beta irradiation may be useful in a developing world setting; however this is yet to be evaluated.

Methodology: Randomised controlled trials were the types of studies included in this review. These trials included participants with glaucoma that were undergoing Trab. All glaucoma categories were included, along with first-time surgery patients and high-risk surgical failure patients. Those undergoing simultaneous bilateral surgery were excluded from the study. The types of interventions included those trials in which Trab with beta irradiation was compared to Trab alone with placebo or other anti-scarring agents. Trials that combined Trab with cataract extractions were excluded from the study.

The primary outcome measures were:

(a) The proportion of failed trabeculectomies at 12 months or more after surgery

(b) Mean intra-ocular pressure (IOP) at 12 months or more.

The secondary outcome measures included:

(c) Adverse effects

(d) Outcomes relating to quality of life or a patient’s perspective of care

(e) Data relevant to economic evaluation

The studies for the review were identified via electronic searches and other searching resources. The Cochrane Central Register of Controlled Trials (CENTRAL) 2012, Issue 3 which is a part of the Cochrane Library was searched. MEDLINE, EMBASE, MetaRegister of Controlled Trials, ClinicalTrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) were also searched. No language or date restrictions were applied to these searches. The Association for Research in Vision and Ophthalmology (ARVO) abstract books was searched using a keyword index search for the relevant studies.

Two independent authors screened the titles and abstracts obtained from the conducted searches. The data extraction and management were carried out by entering the data into RevMan 2 by one review author, with the second independently verifying the data entry. The risk biases of the included studies were assessed using the Cochrane Collaboration’s tool for assessing risk of bias. A fixed-effect model was used as there were only three studies combined. A (posthoc) sub-group analysis was also conducted by ethnic groups.

Applicability/external validity: The authors mention the applicability of beta radiation in developing countries which have a high surgical volume. However, they also acknowledge the significant capital outlay.

Geographic focus: There was no specific geographic focus, however the trials included patients from different ethnicities.

Summary of quality assessment: Overall, high confidence was attributed in the conclusions about the effects of this study. Authors used appropriate methods to identify, include and extract data of included studies. In addition, methods used to analyse findings, and interventions and outcomes, were clearly reported.