Background
PCG is a type of childhood glaucoma, usually beginning in the first five years of life. PCG is caused by an abnormal drainage system in the eye in the absence of other eye or health problems. Fluid naturally produced by the eye builds up causing high pressure within the eye. In children younger than five years, the high fluid pressure can cause the eye to enlarge (distend) leading to a cloudy cornea (clear front part of the eye), decreased vision, tearing, and light sensitivity. Failure to treat this condition may result in partial or total blindness.
PCG is primarily treated by surgery to reduce the pressure in the eye. Some surgeries aim to open up the drainage system of the eye either from the inside (goniotomy) or the outside (trabeculotomy, viscocanalostomy). Other surgeries involve making a new drainage pathway for the eye (trabeculectomy, deep sclerectomy, implantation of a device). Drugs, such as mitomycin C, also may be used during surgeries to prevent the drainage openings from closing up.
Study characteristics
We found six trials comparing different surgeries for PCG. These trials included 102 eyes of 61 children. Two trials were conducted in the USA and one trial in each of these four countries: Egypt, Israel, Lebanon and Saudi Arabia. All trials enrolled infants younger than one year when diagnosed with PCG, and followed them from six months to five years after surgery. No two trials compared the same pair of surgical interventions. One trial compared trabeculotomy versus goniotomy; the second trial compared combined trabeculectomy-trabeculotomy with mitomycin C (CTTM) versus trabeculectomy-trabeculotomy with mitomycin C with deep sclerectomy (CTTM-DS); the third trial compared combined trabeculotomy-trabeculectomy versus trabeculotomy; the fourth trial compared one goniotomy versus two goniotomies; the fifth trial compared trabeculotomy versus viscocanalostomy; and the sixth trial compared goniotomy using a blade versus a laser. The evidence is current to 23 June 2014.
Key results
In our review, no two trials compared the same pair of operations. Further, there were small numbers of children included in each trial (average of 10 children per trial), thus limiting our ability to draw conclusions about the effectiveness of one surgery over another. Four trials reported adverse events, but no trial reported an important difference between pairs of operations. None of the trials reported quality of life or economic data.
Quality of the evidence
The overall quality of the evidence on our review topic was poor. All trials had some limitations in study design, reporting, or both. None of the trials enrolled enough participants to detect an evident difference between surgeries.
Authors' conclusions:
No conclusions could be drawn from the trials included in this review due to paucity of data. More research is needed to determine which of the many surgeries performed for PCG are effective.