You will be provided with the titles and abstracts of a collection of medical RCT reports studying a clinical question -- for instance, the efficacy of an intervention on some medical outcome. Please write a few sentences synthesizing the findings of these reports, which could serve as a conclusion section for a systematic review article. Your response should not include any other text. The RCT reports are below.



Title 1:
Postcataract ptosis. A randomized, double-masked comparison of peribulbar and retrobulbar anesthesia.
Abstract 1:
A randomized, double-masked study of 317 patients was conducted to determine if the incidence of postcataract ptosis is greater with retrobulbar or two-injection peribulbar injection anesthesia.
                Surgery consisted of a planned extracapsular extraction with posterior chamber lens implantation, and no superior rectus bridle suture was used. Ptosis was quantitatively documented preoperatively and postoperatively at 1, 2, 5, and 90 days by the surgeon, photographically at 90 days by a masked observer, and subjectively by the patients. Postcataract ptosis was defined as a drop in the lid margin of 2 mm or greater after correcting for any change in the fellow eye.
                The incidence of ptosis at 90 days in patients given peribulbar anesthesia was 5.8% and in patients given retrobulbar anesthesia 5.5%, and this difference was not statistically significant (P = 0.90). Eighteen percent of patients in both groups reported a change in the appearance of their eyelids. There was a moderate, positive correlation among patients who reported a change in their lid position and objective measurements of ptosis. Preoperative clinical measurements of vertical lid fissure width and levator function, and the appearance of the lid crease or superior sulcus were not predictive for the development of postoperative ptosis at 90 days; the best predictor was the presence of ptosis in the immediate postoperative period.
                The incidence of postcataract ptosis is the same whether two injection peribulbar or retrobulbar anesthesia is used.


Title 2:
A comparison of retrobulbar and periocular anesthesia for cataract surgery.
Abstract 2:
Complications of retrobulbar anesthesia are rare but significant. Periocular anesthesia has been advocated as an alternative to retrobulbar injections. In a prospective, randomized, masked study of 79 consecutive cataract extractions with intraocular lens implantations, 40 patients received retrobulbar injections and 39 patients received periocular injections. In every instance, the volume of the injection was 5 mL. No significant difference in surgeon's assessment of akinesia and anesthesia was found. Supplemental anesthesia was required in eight (21%) of the patients who received retrobulbar injections and in 11 (28%) of the patients who received periocular injections. A significant increase in chemosis was found with periocular injections. There was one complication with retrobulbar anesthesia and none with periocular anesthesia. No significant difference in patient assessment of comfort was found. The efficacy of periocular anesthesia appears to be comparable to that of retrobulbar anesthesia.


Title 3:
A modified retrobulbar block for eye surgery.
Abstract 3:
A modified retrobulbar block (MRB) using a single superomedial injection was compared with the classical retrobulbar block (RB) and peribulbar block (PB) in a randomized, prospective, surgeon-blinded study involving 150 patients undergoing cataract surgery. No serious complication occurred in any of the patients. The MRB produced higher rates of total akinesia in the orbicularis and all the extraocular muscles, which were statistically significant for the orbicularis, superior, inferior and lateral rectus and oblique muscles when compared with RB, and for the superior rectus and oblique muscles when compared with PB. MRB required less supplemental blocks, provided good operating conditions for the surgeon, and achieved high patient acceptance. It is concluded that MRB is a useful alternative method of ocular block for cataract surgery.


Title 4:
One point low volume peribulbar anaesthesia versus retrobulbar anaesthesia. A prospective clinical trial.
Abstract 4:
A prospective trial was conducted on 142 patients who underwent cataract surgery, to compare the efficacy of a single point, low volume peribulbar with that of retrobulbar anaesthesia. It was found that peribulbar anaesthesia is as efficacious as retrobulbar anaesthesia without the associated complications. It also avoids the facial block used by most ophthalmologists to supplement a retrobulbar block, thus markedly reducing the post-operative patient discomfort as well as the total volume of anaesthetic used.


Title 5:
Regional anaesthesia for cataract surgery: comparison of three techniques.
Abstract 5:
Two methods of periocular anaesthesia (PI and PII) were compared with the traditional retrobulbar block in a prospective study of 450 patients undergoing elective cataract extraction and intraocular lens implantation. A solution of local anaesthetic containing equal amounts of 2% lignocaine and 0.5% bupivacaine was used in all the groups. Hyaluronidase (75 IU/10 ml of local anaesthetic solution) was added. Three groups of patients were studied, with 150 patients in each group. The retrobulbar injection (group R) was performed with 4 ml of the anaesthetic solution through the lower eyelid inferotemporally and a further 6 ml was injected for seventh cranial nerve block. In the first periocular technique (group PI) the local anaesthetic was injected inferotemporally (5 ml) through the lower lid and superonasally (5 ml) through the upper lid. In the second periocular technique (PII) the injections were performed inferotemporally (5 ml) and into the medial compartment (2 ml) of the orbit at the medial canthus. Satisfactory anaesthesia could be achieved with all of these methods. Additional block because of insufficient akinesia of the muscles was required in 12% (18/150) in group R, in 19% (28/150) in group PI, and in 11% (16/150) in PII. The medial compartment technique (PII) was associated with the highest percentage of total akinesia of the muscles and lowest reblock rate. All three methods produced sufficient analgesia during surgery and there were no differences in the requirements for additional analgesic drugs during surgery. It is concluded that the medial compartment technique represents a good alternative to retrobulbar block.


Title 6:
Regional anesthesia for cataract surgery: comparison of retrobulbar and peribulbar techniques.
Abstract 6:
METHODS. The features of retrobulbar and peribulbar blocks were compared prospectively in 300 patients undergoing elective, ambulatory cataract surgery. Both techniques were clinically applicable, but to achieve total akinesia of the eye muscles, an additional injection was needed in 13% of the patients with retrobulbar block and in 35% with periocular block. RESULTS. In younger patients (less than 65 years), the number of injections and the volume of the local anesthetic needed to produce a total akinesia of the eye were significantly higher when compared with the elderly.
There is little to choose between peribulbar and retrobulbar block in terms of anaesthesia and akinesia during surgery measuring acceptability to patients, need for additional injections and development of severe complications. Severe local or systemic complications were rare for both types of block.