Reversal of optic disc cupping after trabeculotomy in primary congenital glaucoma

Abstract

Background: The phenomenon of reversal of glaucomatous cupping of the optic disc following lowering of the intraocular pressure (IOP) was originally recognized in infants. We evaluated the change in optic disc cupping with normalization of the IOP after trabeculotomy in primary congenital glaucoma and assessed the factors associated with reversal of cupping.Methods: We reviewed the records of 17 patients (24 eyes) who underwent trabeculotomy between July 1993 and June 1999 and who had been followed for at least I year. Surgical success was defined as IOP less than 22 mm Hg without antiglaucoma medication, stable or reduced optic disc cupping, and lack of further corneal enlargement disproportionate to normal growth. Patients who required more than one surgical procedure to control the IOP and those with cloudy media that precluded documentation of cupping were excluded from analysis. Optic disc cupping was assessed independently before and after surgery by two clinicians. The cup:disc ratio was estimated as the percentage of surface area of the optic disc occupied by cupping in the vertical axis. We accepted a difference of 0.1 or 0.2 in the cup:disc ratio between the two observers in each subjective assessment and used the mean value of the two results for data analysis. If the difference was more than 0.2, the eye was excluded from further study.Results: Of the 17 patients 4 were excluded: 2 because they received antiglaucoma medication to control the IOP postoperatively, I because he underwent more than one surgical procedure to control the IOP during follow-up, and I owing to disagreement in the assessment of the cup:disc ratio between the two observers. Eighteen eyes of 13 patients were thus included in the analysis. Twelve eyes were from boys and six, from girls. The patients were followed for a mean of 43.2 (standard deviation [SD] 30.4) months (range 12 to 90 months). The mean cup:disc ratios pre- and postoperatively were 0.74 (SD 0.20) and 0.60 (SD 0.2 I) respectively (p = 0.003). Of the 18 eyes I I (61. I %) had documented reduction in optic disc cupping. The mean time to stabilization of cupping reversal was 4.8 (SD 2.8) months (range 2 to 12 months). In multivariable analysis the age of the patient at surgery was the only variable significantly associated with reversal of cupping (p = 0.027). The mean age at surgery for the I I eyes with reduction in cupping was 6.9 (range 3 to 15) months, compared with 23.4 (range 12 to 42) months for the 7 eyes with unchanged cupping. The mean preoperative cup:disc ratio was 0.67 (SD 0.17) in the former group and 0.83 (SD 0.17) in the latter group. Six of the seven eyes with unchanged cupping had advanced cupping.Interpretation: Optic disc cupping can be reversed at an early stage of primary congenital glaucoma following successful reduction of IOP. Younger age at surgery was associated with reversal of cupping.