Addition of hyaluronidase to local anaesthetic eye blocks to reduce pain during eye surgery in adults.
We reviewed the evidence on the effectiveness of adding hyaluronidase to local anaesthetic eye block solutions (a numbing medicine injected into the eye to block nerves) to reduce pain and increase participant and surgical satisfaction during eye surgery in adults. We also looked for reports on side effects and cost.
Hyaluronidase is an enzyme (a protein that regulates a chemical reaction in the body) that helps the spread of local anaesthetic through the tissues around the eye. It is widely used as an additive to local anaesthetic eye blocks to give more rapid onset of anaesthesia and reduce or block movement of the eye (called akinesia). With modern eye surgery techniques, fast onset and akinesia are no longer essential requirements, and often surgery can be undertaken pain-free with topical (on the surface of the eye) anaesthesia alone. Hyaluronidase has been associated with infrequent side effects. Therefore, the use of hyaluronidase needs to be justified, which was the aim of this review.
The review is current to 30 June 2017.
We included seven randomized controlled trials (clinical studies where people are randomly put into one of two or more treatment groups) in our review. These involved 500 adults undergoing eye surgery under local anaesthesia. We looked at any additional effect of adding hyaluronidase to local anaesthetic on the pain experienced during eye surgery. We also looked at participant and surgical satisfaction scores and if any harms were reported after using hyaluronidase in the injection solution. None of the studies reported on costs.
Of the seven included trials, we pooled the results of four trials (289 participants) as the results were reported in a similar manner. They found that addition of hyaluronidase did not significantly reduce pain during surgery. Among the three remaining trials (211 participants) lack of data reporting in two trials made it difficult to pool the results. The overall result of looking at all these trials together suggests there was no significant reduction of pain with using hyaluronidase in eye nerve blocks.
We found moderate quality evidence from two trials (122 participants) to suggest that addition of hyaluronidase increased participant satisfaction scores. Three studies involving 141 participants looked at surgical satisfaction, which was reported as superior with hyaluronidase in the two larger studies and not significantly different in one small study (19 participants). None of the included studies reported any harmful effects of hyaluronidase.
Quality of evidence
The included trials that reported on pain during surgery were at low risk for bias. The overall quality of evidence was low because of variations in the effect on pain reduction. We contacted all trial authors to request more information on the trials, but the data were not available.
Moderate quality studies reported greater participant and surgical satisfaction with hyaluronidase.
Analgesia alone does not take into account the full spectrum of the beneficial effects of hyaluronidase. Patient comfort with the eye surgery is also likely to be improved by a speedy onset and reduced eye movements due to hyaluronidase.