A releasable scleral-flap tamponade suture for guarded filtration surgery.

Postoperative complications of filtering surgery are generally associated with overfiltration. We describe a technique that employs an externalized releasable suture in partial-thickness filtering surgery. This suture acts as a tamponade on the anterior surface of the scleral flap, assisting in maintenance of anterior-chamber depth during the early postoperative period. After using this technique, anterior-chamber depths preoperatively and 1 day after surgery were compared in 35 phakic patients. A mean (+/- SD) decrease in anterior chamber depth of 4.6% +/- 12% was found on the first postoperative day. One patient had iridocorneal apposition. The mean intraocular pressure 1 day after surgery was 7.0 +/- 7.0 mm Hg, with one patent having an intraocular pressure of 28 mm Hg. This "tamponade suture" appears to be useful in maintaining the anterior chamber depth in the early postoperative period while permitting satisfactory filtration.

Contrast sensitivity in extended wear of the Boston IV lens.

Over a one-year period we evaluated subjective and objective factors associated with extended wear of Boston IV rigid gas permeable contact lenses. Patients wore the lens on an extended wear schedule, with removal at 2-week intervals for cleaning. We performed keratometry and endothelial cell counts and measured visual acuity, contrast sensitivity, refraction, and corneal thickness at the initial visit (with patients wearing their former glasses or soft or hard lenses) and again at 6 and 12 months (with patients wearing the Boston IV lens). Twenty-four of 31 patients (77%) completed the study. All measured parameters were checked for statistically significant change over time. Contrast sensitivity increased at all spatial frequencies tested, with the largest increments occurring at higher frequencies (P less than .001). The other parameters showed no significant changes (P greater than .05). Our data support the use of contrast sensitivity for qualitative assessment of visual function among contact lens wearers and suggest that contrast sensitivity testing may prove to be a more effective means of evaluating visual acuity in contact lens wearers over time than Snellen acuity.