7
nylon suture. A partial thickness scleral flap, harvested from a gentamycin soaked donor eye,
and fashioned to cover the tube, was sutured to the cornea anteriorly and to the sclera
posteriorly using 10-0 nylon sutures. If necessary, a notch was cut in the posterior edge of the
flap to ensure that the Vicryl suture around the tube was not covered and thus subject to an
inflammatory response that would promote its eventual dissolution. Conjunctiva was
reapposed using 10-0 Vicryl sutures at least two of which were through clear cornea nasally
and temporally, so that the scleral patch was completely covered. Air was injected into the
anterior chamber through the paracentesis. Subconjunctival injections of gentamycin and
dexamethasone were given inferiorly and the eye was patched and shielded after the
instillation of atropine 1% and combined steroid/antibiotic ointments.
Statistical Analysis
Kaplan-Meier survival curves were generated and the log-rank test statistic was used
to determine if there was a difference in survival profiles for different diagnoses. Proportional
hazards regression was conducted to generate a survival model that compared patients who
did not have any prior surgery as opposed to the rest and patients younger than 18 months as
opposed to those older than 18 months. Fisher's Exact Test was used to assess the association
between tube exposure and uveitis. SAS software (SAS Institute Inc., SAS/STAT User's
Guide, Version 8. Cary, NC, USA: SAS Institute Inc., 1999.) was used for the statistical
analysis.
