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Editors Selection IGR 7-3

Surgical Treatment: Phacotrab versus phacotrabeculotomy/deep sclerectomy

Comment by Louis Cantor on:

21762 A prospective trial of phaco-trabeculotomy combined with deep sclerectomy versus phaco-trabeculectomy, Lüke C; Dietlein TS; Lüke M et al., Graefe's Archive for Clinical and Experimental Ophthalmology, 2008; 246: 1163-1168

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Lüke et al. (1265) present a comparison of a consecutive series of patients undergoing combined glaucoma and cataract surgery. Patients received either phaco/trabeculectomy (PTE) versus phaco/trabeculotomy/deep sclerectomy (PDSTO). This is a limited consecutive series consisting of 43 patients. It is unclear from the methods how patients were chosen for one procedure over the other. In the end, 23 patients underwent the PDSTO procedure and 20 patients underwent the PTE procedure. Without proper randomization there may be significant bias introduced in to the author's results and subsequent conclusions. In addition, 39 of the 43 patients completed the study. One patient died during follow up and three patients were excluded due to difficulties during surgery. Reportedly, these three patients were subsequently replaced. Replacing patients who develop complications leads to bias in the study results as well. Surgical complications are an important aspect of evaluating any surgical technique. The authors failed to clarify if the three replacements were merely added the original total or simply replaced those that had a surgical problem. Based on the author's data, the aggregate 'success' at one year was poor in both groups. Only 35% of the PTE and 50% of the PDSTO patients were able to achieve an IOP less than 22 and the difference between the two was not significant. Allowing medications for a 'qualified success' improves the results to 80% and 89.5% respectively. However, this difference was also not significant. Twenty percent of the PTE and 50% of the PDSTO patients achieved an IOP less than 18 mmHg without medications which the authors did find to be statistically significant. The survival curves also appeared different between the groups and favored the PDSTO procedure. From the data presented, it is difficult to compare the two treatment groups in this study. At baseline the PDSTO group was on fewer medications than in the PTE group though it was not clear if this difference was significant. The high incidence of surgical complications suggests the surgical techniques employed in this study should be questioned. In addition, a significant percentage of combined phaco/trabeculectomy procedures are performed utilizing an adjunctive antimetabolite, which was not utilized in this study. The authors suggest that the comparison between the groups is more acceptable if antimetabolites are eliminated. However, this is not consistent with common surgical technique and biases the phaco/trabeculectomy to a higher rate of failure. In summary, while the authors present interesting data comparing two techniques for combined glaucoma and cataract surgery, questions regarding the methodology make the comparison difficult and render the authors conclusions to the suspect. A larger series of patients, utilizing a prospective masked randomization protocol and standardized common surgical techniques would be required to more fully determine the possible difference between these two procedures when combined with cataract surgery.

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