Aqueous shunts for glaucoma

Full citation: Jin C, Chen X, Law A, Kang Y, Wang X, Xu W, Yao K. Different-sized incisions for phacoemulsification in age-related cataract. Cochrane Database of Systematic Reviews 2017, Issue 9. Art. No.: CD010510. DOI: 10.1002/14651858.CD010510.pub2

Review aim
The aim of this Cochrane Review was to find out if the size of the incision (cut in the eye) during cataract surgery results in a difference in outcome of cataract surgery. We found 26 studies that answered this question.

Key messages
Some, but not all, surgical techniques using smaller incisions were associated with less astigmatism; however, the differences were small and the evidence was uncertain. There was little evidence to suggest any important effects on vision. There were limited data on adverse effects and no evidence on the effects of different-sized incisions on quality of life.

What was studied in this review?
As people age the clear lens in the eye can become cloudy, which is known as a cataract. An operation can be performed to remove the cataract and replace the cloudy lens with a clear artificial lens. This surgery is safe and restores sight in almost all cases. Age-related cataract is one of the leading causes of blindness worldwide.

One problem that can occur after cataract surgery is that due to the surgery the front of the eye is no longer a perfectly curved shape. This can result in blurred or distorted vision and is known as astigmatism. The vision problems arising from astigmatism can be corrected with spectacles. It is commonly believed that the smaller the cut or incision made in the eye during cataract surgery, the less chance of astigmatism.

Key results
We searched for studies that compared different-sized incisions for cataract surgery in people with age-related cataract. This review includes 26 studies from Europe and Asia.

We found the following results.

• Some, but not all, surgical techniques using smaller incisions were associated with less astigmatism, however the differences were small and the evidence was uncertain (low- and very low-certainty evidence).
• In general, there may be little or no difference in visual acuity based on whether a smaller or larger incision is made (low-certainty evidence).
• There were no consistent effects on other signs such as thickness of the cornea (front of the eye) and number of cells in the front of the eye (low- and very low-certainty evidence).
• Adverse effects were not reported by most of the included studies.
• None of the studies reported on the quality of life of participants.

How up-to-date is this review?
We searched for studies published up to 28 October 2016.