Objectives:

Surgery for age-related cataract is the highest volume surgical procedure in the Medicare population. In the United States, approximately 1.5 million cataract operations were performed on Medicare beneficiaries in 1996. Cataract surgery is almost exclusively performed as an outpatient procedure and usually involves the administration of a local anesthetic in addition to systemic sedation administered by an anesthesiologist or nurse anesthetist. There is considerable national and international variation in anesthesia management strategies for cataract surgery. The principal objectives of this Evidence Report are to summarize the published literature on (1) the risks and benefits associated with the use of one form of regional anesthesia over another and (2) the risks and benefits associated with different approaches to sedating the patient for cataract surgery.

Search Strategy:

The primary sources for the literature review were PubMed and the Cochrane Collaboration's database of controlled clinical trials. Medical subject heading (MeSH) terms used in the searches included cataract, anesthesia, and hypnotics or sedatives. All included studies were published between 1968 and 1999.

Selection Criteria:

An article was included in the Evidence Report if it (1) addressed cataract surgery using local anesthesia (with or without sedation) in an adult population, (2) was a controlled trial or a case series with more than 100 cases, and (3) provided outcomes specifically related to the research questions.

Data Collection and Analysis:

After assessment of 739 potentially relevant citations, by abstract or full manuscript review, 141 were identified that met eligibility criteria. Study quality was assessed and data abstracted by pairs of reviewers. Results are presented in evidence tables and the quality of evidence for specific questions graded as strong, moderate, weak, or insufficient. Supplemental analyses include a decision analysis comparing alternative management strategies, an analysis of early postoperative morbidity and mortality based on Medicare claims data, and an analysis of patient perceptions of different anesthesia strategies from the Study of Medical Testing for Cataract Surgery.

Main Results:

Of the 141 reviewed studies, 122 focused on local anesthesia techniques either alone or in combination with sedation strategies. Of these, 86 were randomized clinical trials and 36 were noncontrolled studies. Nineteen studies, all of which were randomized clinical trials, specifically focused on issues relating to sedation. The mean overall methodology quality score (maximum = 100) was 46 for randomized clinical trials and 33 for noncontrolled studies.

The effectiveness of a regional block for cataract surgery has traditionally been assessed by describing the completeness and adequacy of globe akinesia (i.e., prevention of eye movement) and pain control.

Regarding globe akinesia, there was strong evidence of equivalent effectiveness of peribulbar and retrobulbar anesthesia. There was insufficient evidence to compare subconjunctival/sub-Tenon's anesthetic block with peribulbar and retrobulbar blocks regarding akinesia. However, the rates of adequate akinesia appeared similar across the three techniques. There was weak evidence that adding hyaluronidase or using certain specific anesthetic agents over others produced superior akinesia. There was insufficient evidence to reach any conclusion regarding the relationship between akinesia and the volume of anesthetic used or the speed of injection.

Regarding pain associated with administration of the block, there was weak evidence to suggest that peribulbar injection was slightly less painful than retrobulbar injection, moderate evidence that subconjunctival/sub-Tenon's block was less painful than retrobulbar block, and insufficient evidence that subconjunctival/sub-Tenon's block was less painful than peribulbar block.

Regarding pain control during surgery, all of the major classes of techniques reported yielded good or excellent intraoperative pain control. The evidence was strong that retrobulbar and peribulbar techniques produce equivalent pain control during cataract surgery, and there was moderate evidence indicating superiority of pain control using subconjunctival/sub-Tenon's approaches compared with retrobulbar block. There was insufficient evidence to determine whether peribulbar or subconjunctival/sub-Tenon's anesthesia results in better pain control during surgery. There was strong evidence that retrobulbar block results in less pain during cataract surgery than topical anesthesia, moderate evidence that peribulbar block results in less pain during cataract surgery than topical anesthesia, and weak evidence that subconjunctival/sub-Tenon's block produces better pain control than topical anesthesia during cataract surgery.

Regarding specific agents used for local anesthesia, virtually all agents reported had high rates of excellent pain control, and there was insufficient evidence to determine if some agents produced better pain control during surgery than others.

Complications related to different anesthesia techniques were rarely and not systematically reported in the literature. The most important ocular and systemic complications are sufficiently rare that the reported frequency in the reviewed studies was almost invariably zero. Comparison of complication rates was also limited by wide variation in outcome definitions.

Regarding sedation strategies, weak evidence was found that intravenous or intramuscular sedation or analgesia is associated with improved anxiety control, pain relief, and patient satisfaction. There was insufficient evidence to suggest that one sedative or analgesic regimen was superior to another.

An analysis of a large Medicare claims data set was directed at ascertaining risk factors for readmission within 1 week following cataract surgery. Increasing age, medical comorbidity, and inpatient surgery were found to be predictive of readmission. Risk of readmission was greater for surgery performed in an office-based setting, but the relatively small number of individuals undergoing surgery in this setting limited the significance of this finding.

A decision analysis of alternative anesthesia management strategies indicated that strategies employing retrobulbar or peribulbar block yielded higher respondent preference values from medical experts than strategies employing topical anesthesia. In addition, among strategies employing retrobulbar or peribulbar block, the availability of an anesthesiologist either on call or present to provide intravenous sedation was preferred over having no anesthesiologist present. Having an anesthesiologist present for every case was associated with increased costs, albeit at increased preference values relative to simply having an anesthesiologist on call. Additional input from patients regarding their preferences and further clinical research are needed to validate the findings of the decision analysis.

An analysis of data on patient reports of their cataract surgical experience based on 19,250 surgeries from the Study of Medical Testing for Cataract Surgery indicated a high level of satisfaction with anesthesia management regardless of strategy, greater intraoperative pain with topical than injection anesthesia, and a greater rate of postoperative drowsiness and nausea when intravenous agents were used.

High priorities for additional research are improving the methodological quality of studies in the field, assessing patient (and surgeon) preferences (utilities) for different anesthesia management strategies and outcomes, and assessing the cost-effectiveness of intravenous sedation and monitoring by anesthesia personnel.

Conclusions:

A variety of commonly employed anesthesia management strategies for cataract surgery appear to be safe and highly effective. Topical anesthesia does not provide as complete pain control as do the various injection techniques, although this technique is clearly quite effective and avoids rare complications potentially associated with injection techniques. There is only weak evidence that intravenous or intramuscular sedation or analgesia improve anxiety control, pain relief, and patient satisfaction with cataract surgery.