Maul et al. first reported the use of this procedure in 1980, for a child with severe bilateral primary congenital glaucoma who had not been controlled with initial goniotomy. After that, the results of this procedure have been mostly reported in Middle Eastern and Indian populations, where it was used preferentially because it was felt that congenital glaucoma did not respond as well to angle surgery as previously described in western populations. The intended mechanism of action for combining these two procedures is to gain access to dual outflow, through Schlemm’s canal and/or the trabeculectomy fistula. One study in Saudi Arabia which prompted an institution to search for other options, such as this combined procedure, reported a disappointing 67% success rate with trabeculotomy alone at one year follow-up. They hypothesized that the poor results compared with those from the western literature were because these patients had more severe degree of disease due to a higher rate of consanguinity and poor prognostic indicators such as larger corneal diameters, presentation since birth, and higher intraocular pressures.

A small study of nine Arab children, with primary congenital glaucoma, who underwent primary trabeculotomy/trabeculectomy before one year of age, demonstrated a much better success rate of 93.5% in contrast with 72% of those that underwent trabeculectomy alone. A theoretical advantage of the combined procedure is that it provides two major outflow pathways, the incised trabecular meshwork by the trabeculotome and the excised trabecular meshwork block and filtering bleb by the trabeculectomy. A practical advantage was that in those cases where Schlemm’s canal could not be identified, something that has been reported in up to 11–15% of trabeculotomies, the procedure would not result in failure, since the trabeculectomy pathway could still function.

Mandal et al. reported a 94.4% success rate of primary trabeculotomy-trabeculectomy in 122 eyes with primary congenital glaucoma operated in India, with a mean follow-up of approximately a year. Complications included one case each of premature penetration into anterior chamber, vitreous prolapse and Descemet detachment, plus 10 cases of shallow anterior chamber from which only two required surgical reformation.

trabeculectomy presents special difficulties in childhood glaucoma. The eye is large and the limbal anatomy is frequently distorted, and lack of familiarity with these unusual eyes can lead to complications such as iris and ciliary body incarceration and vitreous loss. Another problem is that the superior conjunctival area is utilized, and even after successful surgery, with a normal life expectancy, there is a high likelihood that a significant proportion of these patients will need further surgery within their lifetimes.

Currently, there are numerous choices for the treatment of pediatric glaucoma depending on the type of glaucoma, the age of the patient, and other particularities of the condition discussed in this review. Traditionally, goniotomy and trabeculotomy ab externo have been the preferred choices of treatment for congenital glaucoma, and a variety of adult procedures adapted to children have been utilized for other types of pediatric glaucoma with variable results and complications. More recently, seton implantations of different types have become more popular to use in children, and newer techniques have become available including visualized cannulation and opening of Schlemm’s canal, deep sclerectomy, trabectome, and milder more directed cyclodestructive procedures such as endolaser and transcleral diode laser cyclophotocoagulation.

Thank you for your reply. In Hong Kong or in your institution, at least , would you do combined surgery in an advanced case straight away or would you be guided by certain factors?

Please follow Dr A K Mandal's (LV Prasad Eye Institute, India) work. He has extensively reported his results of Combined Trabeculotomy with Trabeculectomy in children with PCG, Aniridia, SWS. It works best for children

I decide to do combined or simple 360 trabeculotomy based on gonioscopy.

If part of the trabecular meshwork is visible (Type 1 angle, according to Sampaolesi), then a trabeculotomy is sufficient, although I really try to get 360 degrees of treatment. In type 2, the iris is so anteriorly pulled forward that a simple trabeculotomy might not be sufficient, and a combined trabeculectomy-trabeculotomy is a better option.