Cataract is the most common cause of low vision and blindness; it is usually due to the normal ageing process but may be found in younger people. Cataract occurs as loss of the natural clearness of the lens of the eye. A cataract is treated by surgery to remove the lens and replace it with an artificial one. Surgery ideally should be performed within six months of diagnosis to avoid further loss of vision. Debate continues as to which local anaesthetic technique provides better pain relief for the patient and facilitates the task of the surgeon at the same time.
Topical anaesthesia is provided by placing local anaesthetic drops or gel of local anaesthetics on the surface of the eye. Sub-Tenon's anaesthesia is provided by first numbing the surface of the eye with local anaesthetic drops, holding the tissue lining (conjunctiva and Tenon’s capsule) in front of the eye with blunt tweezers and making a small nick in it using curved blunt-ended scissors. A small blunt sub-Tenon's cannula is passed through this hole to inject local anaesthetic into sub-Tenon's space. Advantages of topical anaesthesia over sub-Tenon's block include reduced time in administration, less pain during administration and shorter duration of action, allowing the person to rapidly regain sight after surgery.
We included eight randomized controlled trials in the review, and we based our analysis on seven of these: two cross-over trials that included 125 participants, and five parallel trials involving 492 participants. The mean age of participants varied from 71.5 years to 83.5 years. Oral sedation was used for two trials only. No trial used oral analgesics before the operation, and no trials mentioned their source of funding. This review showed that sub-Tenon’s anaesthesia provided slightly better pain relief than topical anaesthesia during cataract surgery. The difference was equal to 1.1 on a scale from 0 to 10. Pain on the day after surgery was slightly lower for participants who received topical anaesthesia, and the difference was equivalent to 0.2 on a scale from 0 to 10. Both surgeons and participants preferred sub-Tenon’s anaesthesia. However, all trials were performed at a time when surgeons were only starting to use topical anaesthesia. There was not enough evidence from included trials to say whether one anaesthetic technique would be associated with a lower or higher incidence of important surgical complications during surgery (posterior capsular tear, iris prolapse) that may lead to postoperative complications and eventually to poorer vision. Topical anaesthesia and sub-Tenon’s anaesthesia therefore are accepted and safe methods of providing anaesthesia for cataract surgery.
Both topical anaesthesia and sub-Tenon's anaesthesia are accepted and safe methods of providing anaesthesia for cataract surgery. An acceptable degree of intraoperative discomfort has to be expected with either of these techniques. Randomized controlled trials on the effects of various strategies to prevent intraoperative pain during cataract surgery could prove useful.
Local anaesthesia for cataract surgery can be provided by sub-Tenon's or topical anaesthesia. Both techniques offer possible advantages. This review, which originally was published in 2007 and was updated in 2014, was undertaken to compare these two anaesthetic techniques.
Our objectives were to compare the effectiveness of topical anaesthesia (with or without intracameral local anaesthetic) versus sub-Tenon's anaesthesia in providing pain relief during cataract surgery. We reviewed pain during administration of anaesthesia, postoperative pain, surgical satisfaction with operating conditions and patient satisfaction with pain relief provided, and we looked at associated complications.
We searched the Cochrane Central Register of Controlled Trials, MEDLINE and EMBASE (last search in November 2014) and the reference lists of published articles. We looked for conferences abstracts and trials in progress and placed no constraints on language or publication status.
We included all randomized studies that compared sub-Tenon's anaesthesia versus topical anaesthesia for cataract surgery.
We assessed trial quality and extracted data in the format allowing maximal data inclusion.
We included eight studies in this updated review but could retain in the analysis only seven studies on 742 operated eyes of 617 participants. Two cross-over trials included 125 participants, and five parallel trials included 492 participants. These studies were published between 1997 and 2005. The mean age of participants varied from 71.5 years to 83.5 years. The female proportion of participants varied from 54% to 76%. Compared with sub-Tenon's anaesthesia, topical anaesthesia (with or without intracameral injection) for cataract surgery increases intraoperative pain but decreases postoperative pain at 24 hours. The amplitude of the effect (equivalent to 1.1 on a score from 0 to 10 for intraoperative pain, and to 0.2 on the same scale for postoperative pain at 24 hours), although statistically significant, was probably too small to be of clinical relevance. The quality of the evidence was rated as high for intraoperative pain and moderate for pain at 24 hours. We did find differences in pain during administration of local anaesthetic (low level of evidence), and indications that surgeon satisfaction (low level of evidence) and participant satisfaction (moderate level of evidence) were less with topical anaesthesia. There was not enough evidence to say that one technique would result in a higher or lower incidence of intraoperative complications compared with the other.