Peribulbar anaesthesia. A clinical evaluation of two different anaesthetic mixtures

Needle-based blocks for the 21st century ophthalmology

PURPOSE

This paper reviews history of the needle orbital blocks used in the earlier centuries and how they have evolved towards safer anaesthesia in the modern clinical practice.

METHODS

Material is derived from literature searches from major ophthalmic and anaesthetic journals on the use of orbital needle blocks over earlier centuries.

RESULTS

Needle-based anaesthetic techniques were described shortly after the invention of reliable medical needles. Atkinson popularized the classical retrobulbar block in a series of papers published in the early 20th century. This technique,which utilises a relatively long needle inserted towards the apex of the muscle cone behind the globe, has been criticized by some as unsuitable for modern 21st century ophthalmic surgery because of the extremely rare potential for serious complications. Satisfactory anaesthesia and akinesia can be obtained with short sharp or dull needles with slightly higher volumes of local anaesthetic agent placed in the farthest inferotemporal quadrant.

CONCLUSION

Aside from relative safety, modern needle blocks offer the advantage of lid akinesia without a need for a second injection for the seventh nerve that is often performed con-comitantly with retrobulbar block.

[Hyaluronidase: Here we go again]

OBJECTIVE

To summarize the benefits and lateral effects of hyaluronidase (H) use in ophthalmologic anaesthesia and to address its unavailability in current practice in France.

DATA SOURCES

The Medline data bank and the Cochrane database were consulted. The keywords employed separately or in combination were: H, regional anaesthesia, ophthalmologic surgery, local aneasthetics myotoxicity, diplopia.

STUDY SELECTION

Original articles since 1949 were selected. We also selected isolated clinical cases according to their relevance compared with the existing literature.

DATA SYNTHESIS

H is a "spreading factor" of animal origin used as an adjuvant in ophthalmic anaesthesia for more than half a century. It allows a moderate better block quality with a slightly quicker onset. It also limits the acute intraocular pressure increase secondary to periocular injection and seems to have a protective effect against local anaesthetics myotoxicity resulting in postoperative strabismus. However, during these last 50 years, numerous studies often ended in divergent results.

CONCLUSION

H seems to be a useful adjuvant in ophthalmologic anaesthesia in spite of his current unavailability in France. Recombinant H could be the solution in the near future.

The methodologic quality of clinical trials on regional anesthesia for cataract surgery

OBJECTIVE

To assess the methodologic quality of published randomized trials of regional anesthesia management strategies for cataract surgery.

DESIGN

Literature review and analysis.

METHOD

We performed a systematic search of the literature to identify all articles pertaining to regional anesthesia for cataract surgery on adults. Overall quality scores and scores for individual methodologic domains were based on the evaluations of two investigators experienced in methodologic research who independently reviewed all relevant articles using a quality abstraction form.

MAIN OUTCOME MEASURES

Study quality in each of five domains: representativeness, bias and confounding, intervention description, outcomes and follow-up, and statistical quality and interpretation.

RESULTS

Eighty-two randomized clinical trials were identified with a mean overall quality score of 44%. The mean domain scores ranged from 37% for representativeness to 58% for outcomes and follow-up. Forty percent or fewer studies received the maximum score for reporting the setting, the population, and the start and end dates; describing the inclusion and exclusion criteria; adequately randomizing subjects; and adequately masking individuals participating in the study. Key outcomes were often inadequately reported, including the distribution of patient-reported pain scores and the mean surgical time.

CONCLUSIONS

Greater attention to methodologic quality and detailed reporting of study results will improve the ability of readers to interpret the results of clinical trials assessing regional anesthesia for cataract surgery.

Synthesis of the literature on the effectiveness of regional anesthesia for cataract surgery

OBJECTIVE

To synthesize the findings of the randomized trials of regional anesthesia management strategies for cataract surgery.

DESIGN

Literature review and analysis.

METHOD

The authors performed a systematic search of the literature to identify all articles pertaining to regional anesthesia during cataract surgery on adults. One investigator abstracted the content of each article onto a custom-designed form. A second investigator corroborated the findings. The evidence supporting the anesthesia approaches was graded by consensus as good, fair, poor, or insufficient.

MAIN OUTCOME MEASURES

Evidence supporting the effectiveness of different forms of regional anesthesia.

RESULTS

There was good evidence that retrobulbar and peribulbar blocks provide equivalent akinesia and pain control during cataract surgery. Additionally, sub-Tenon's blocks were at least as effective as retrobulbar and peribulbar blocks. There was good evidence that retrobulbar block provides better pain control during surgery than topical anesthesia, and there was fair evidence that peribulbar block provides better pain control than topical anesthesia.

CONCLUSIONS

This synthesis of the literature demonstrates that currently used approaches to anesthesia management provide adequate pain control for successful cataract surgery, but there is some variation in the effectiveness of the most commonly used techniques. Data are needed on patient preferences to determine the optimal strategies for anesthesia management during cataract surgery.

Single injection peribulbar anaesthesia. Total upper eyelid drop as an end-point marker

A prospective, observer blinded study on 51 patients undergoing cataract surgery was conducted to assess Total Upper Eyelid Drop as a new end-point marker to single injection peribulbar block. At present, no such clinical marker exists to stop clinicians injecting more than necessary volumes of local anaesthetic and therefore to prevent dangerous increases in intra-ocular pressure. Using this technique, satisfactory ocular akinesia was achieved in 90% of eyes 10 min after injection. Operating conditions were satisfactory in 98% of cases. The mean (range) volume injected was 9.1 (4-15) ml. The mean increase in intra-ocular pressure immediately after injection was 6.9 mmHg, decreasing to 0.7 mmHg after 5 min without the application of ocular compression. We found a negative correlation between the increase in intra-ocular pressure and the volume of injection (p < 0.002), which has never previously been reported. We conclude that Total Upper Eyelid Drop is a reliable endpoint marker for producing satisfactory operating conditions for cataract surgery while minimising increases in intra-ocular pressure and its use may therefore avoid the risks associated with ocular compression.

Topical anesthesia: Proxymetacaine versus Amethocaine for clear corneal phacoemulsification

PURPOSE

To evaluate the use of proparacaine (Proxymetacaine) versus tetracaine (Amethocaine) as the topical anesthetic agent for phacoemulsification cataract surgery using a 3.5 mm clear corneal sutureless incision.

SETTING

Harold Wood Hospital, Romford, Essex, United Kingdom.

METHODS

This prospective study comprised 40 randomly selected patients. Twenty were given Proxymetacaine and 20, Amethocaine. The level of discomfort experienced during delivery of the topical anesthetic agent and during and immediately after surgery was measured using a pain score. During surgery, topical anesthesia was supplemented by intracameral lignocaine 1%.

RESULTS

Patients given Proxymetacaine experienced no stinging sensation during its administration; those given Amethocaine reported varying degrees of discomfort. The difference between groups was statistically significant (P < .01). There was no difference between groups in the amount of discomfort experienced intraoperatively or postoperatively.

CONCLUSION

Proxymetacaine is the topical analgesic of choice for phacoemulsification because it produced no discomfort on administration yet had the same analgesic properties as Amethocaine.

Topical anaesthesia for cataract surgery

First, do no harm. We believe that the analgesia provided by topical anaesthetic is adequate for small-incision cataract surgery and does not compromise the safety of the surgery. In addition, the lack of amaurosis is ideal for day-case surgery, which itself is increasingly popular. If preventable, why not prevented? The greatest attraction of topical anaesthesia is its complete absence of the complications described for injectional local anaesthetic techniques. We therefore recommend that our colleagues consider topical anaesthetic for patients undergoing small-incision cataract surgery under local anaesthesia. Our policy for the past 3 years has been to use only topical or general anaesthetics for cataract surgery.