Prophylactic treatment of intraocular pressure elevation after uncomplicated cataract surgery in nonglaucomatous eyes – a systematic review

Methodological quality of the review: Medium confidence

Author: Jakob Lysholk Holm, Daniella Bach-Holm, Lars Morten Holm and Anders Højslet Vestergaard

Region: Not stated

Sector: Service delivery

Subsector: Quality of clinical careEquity focus: Not stated

Review type: Effectiveness review

Quantitative synthesis method: Narrative synthesis

Qualitative synthesis method: Not applicable

Background:
Cataract is the leading cause of blindness and low vision worldwide, and cataract surgery is the most commonly performed surgical procedure, with more than two million surgeries per year in the USA alone. The preferred technique today for this procedure involves the use of phacoemulsification and ophthalmic viscosurgical devices (OVD), and implantation of a foldable intraocular lens (IOL). A major concern regarding this technique is the related intraocular pressure (IOP) elevation in the early postoperative period. A postoperative elevated IOP is very common, resulting in IOP spikes >30 mmHg within the first 24 hours in up to 26% of eyes operated with the technique mentioned above. However, the severity of an elevated IOP, after uncomplicated cataract surgery in an otherwise healthy eye, is still up for debate.

Objectives:
The purpose of this systematic review was to evaluate the literature regarding prophylactic treatment of intraocular pressure (IOP) elevation after uncomplicated cataract surgery to provide an evidence-based guideline for cataract surgeons.

Main findings:
A total of 24 studies were included by the authors. 23 studies were randomised controlled trials (RCTs) and one was a good quality nonrandomised study. The 24 articles reported on 45 treatment arms, with 14 different active substances as the intervention: Timolol, bimatoprost, latanoprost, travoprost, acetazolamide, dorzolamide, brinzolamide, apraclonidine, brimonidine, latanoprost + timolol, dorzolamide + timolol, brinzolamide + timolol, brinzolamide + brimonidine and brimonidine + timolol. The remaining of the studies included only treatment with eye drops or eye gel.

Overall, 2,333 eyes of 2,228 patients were involved, with 1,564 eyes exposed for the 14 different interventions and 769 eyes participating in control groups. The majority of the eyes in 34 treatment arms received the medication postoperatively, and only 11 treatment arms started the medication preoperatively. Of the 11 treatment arms, five of them also administered medication after the surgery.

The NRS was graded moderate risk of bias. Nine RCTs were judged as high-quality evidence, 12 trials as moderate and three as low-quality evidence.

Findings of this review showed consistency between the trials, which studied the effect of timolol, and presented a relative effect from 18.6% to 29.6% at 3-8 hours, and 9.8% to 23.6% at day one. In addition, authors note that timolol, latanoprost and travoprost alone, or medications containing timolol as an additive active substance, such as dorzolamide + timolol, brinzolamide + timolol and brimonidine + timolol, are characterised by a good relative IOP-lowering effect, which can be gained by a single dose postoperatively.

Methodology:
Review authors conducted a search on Embase, PubMed and grey literature database, with no date restrictions applied. Screening of studies for inclusion was conducted by one reviewer.

Studies were included if they met the following criteria: (1) randomised controlled trials (RCT) were preferred, but good-quality prospective nonrandomised studies (NRS) were taken into consideration; (2) adults undergoing uncomplicated cataract surgery with modern surgery technique consisting of phacoemulsification, foldable IOL and the use of OVD; (3) prophylactic treatment with an IOP-lowering drug and IOP measurements before and after surgery; (4) a description of the drug class, active substance or sales name, along with the time for administration, dose and the time for measurement of the effect; and (5) full text available in English or German. Exclusion criteria were as follows: (1) patients with other conditions known to affect the IOP, such as glaucoma, exfoliation syndrome or pigment dispersion; (2) previously operated eyes; and (3) clinical trials made before 1980 because of the invention of OVD.

Quality assessment of randomised controlled trials was performed using the Cochrane Handbook for Systematic Reviews of Interventions. The ROBINS-I tool was used for NRS. Also, the Grading of Recommendation, Assessment, Development and Evaluation Working Group (GRADE) criteria were used to rate the quality of evidence.

Primary outcome measures were the absolute IOP-lowering effect and the relative IOP-lowering effect of the different drugs after cataract surgery. Authors synthetised the evidence narratively.

Applicability/external validity:
In this review, authors noted only covering measurements at three to eight hours and one day after intervention, which demonstrated good pressure-lowering results for medications containing timolol. However, findings may not be generalisable or applicable to other settings due to mixed findings of other studies with similar objectives.

Geographic focus:
Authors did not report the geographical location on included studies.

Summary of quality assessment:
Overall, medium confidence was attributed to findings of this review. Some of the limitations of the review included the limited search of literature and methods used for study selection, and data extraction was not reported, indicating potential reporting bias. However, quality assessment and reporting of results with regards to risk of bias was done well, and limitations were adequately acknowledged.