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Editors Selection IGR 16-1

Surgical Treatment: Pediatric glaucoma

Comment by Franz Grehn on:

60800 Comparison of 360-degree versus traditional trabeculotomy in pediatric glaucoma, Lim ME; Neely DE; Wang J et al., Journal of AAPOS, 2015; 19: 145-149

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Pediatric glaucoma has always been a challenging therapeutic issue as it needs specific surgery at a very early age in a rare disease. Although most of the cases are being treated in tertiary care centers, the low frequency of these surgical procedures have made innovative changes in surgical techniques difficult. Hitherto, goniotomy and traditional trabeculotomy were the two procedures used in most centers, as these operations aim at opening the malformed trabecular meshwork as the primary site of outflow resistance.

Three hundred-sixty-degree trabeculotomy is a logical approach that opens up the complete circumference of the malformed trabecular meshwork. It has been performed by a few centers since its introduction in 1960 using a suture for trabeculotomy. However, the visibility is of the suture during probing of Schlemm's canal is limited and specific serious complications by misdirection of the suture may occur. The introduction of an illuminated catheter as used for canaloplasty has now facilitated the technique and many pediatric glaucoma surgeons have adopted this technique.

360-degree trabeculotomy is a logical approach that opens up the complete circumference of the malformed trabecular meshwork.

The present paper compares 77 eyes treated with traditional trabeculotomy to 14 eyes treated with 360-degree catheter trabeculotomy in a non-randomized comparison of the two techniques. The success criteria was absence of additional surgery at the one-year follow-up. In the traditional trabeculotomies, 37 of 77 eyes completed the one-year follow-up (IOP 17.05 ± 5,92 mmHg) and the success rate as defined above was 58.44% (all eyes). In the 360-degree trabeculotomy group, seven of 14 eyes completed the one-year follow up (IOP 11.00 ± 2.31 mmHg) and the success rate as defined above was 85.71% (all eyes). In three eyes, 360-degree trabeculotomy was attempted but could not be completed due to a block along the circumference of Schlemm's canal. These eyes received a partial catheter cut-down trabeculotomy or a traditional trabeculotomy. Two of them were failures and required additional surgery.

If the results relating to primary congenital glaucoma only (PCG) were analyzed separately, all 11 PCG eyes treated with 360-degreee trabeculotomy were successful (100%) but only 32 of 58 PCG eyes treated with traditional trabeculotomy were successful (55,17%). The circumferential introduction of the catheter was possible in all PCG glaucoma eyes.

The rate of additional medication at one-year follow-up was approx. 0.5 in either technique for all eyes, and 0.2 (360-degree trabeculotomy) and 0.3 (traditional trabeculotomy) in the PCG only group, respectively.

The comparison of the two techniques results in a better outcome after 360-degree illuminated catheter trabeculotomy, in particular in primary congenital glaucoma. However, due to the non-randomized design of this comparison and the unequal number of eyes in the compared groups (five times more traditional trabeculotomies), the favorable results of 360-degreee trabeculotomy must be considered still somewhat preliminary. Another challenge is the fact that three eyes (non PCG eyes) could not be probed circumferentially, but were not counted as failures of the 360-degree trabeculotomy group. In contrast, they were included into the traditional trabeculotomy group. If one includes these three eyes as failures into the 360-degree trabeculotomy group (as they were intended to receive 360-degree trabeculotomy), five out of 17 eyes were failures (29.41%) in an intention-to-treat analysis, although one eye was successful as a traditional trabeculotomy. This critical view underlines the authors' comments that 360-degree trabeculotomy is particularly successful in primary congenital glaucoma but still has some challenges in secondary pediatric glaucoma.

This paper is a very valuable contribution to the increasing experience with 360-degree catheter trabeculotomy and supports the results of other studies showing high efficacy of 360-degree trabeculotomy when compared to goniotomy or combined MMC trabeculotomy/trabeculectomy.

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