Faculty Bibliography

We performed a retrospective study on 100 eyes of 55 consecutive patients to compare the stereoscopic quality of simultaneous stereoscopic disk photographs and the reproducibility of optic nerve assessments using the Nidek 3Dx system and the Donaldson fundus camera. Photographs were taken on the same eyes on the same dates and reviewed independently by one clinician three times in a randomized, masked fashion. Mean cup/disk ratios using the Nidek 3Dx system were similar to mean cup/disk ratios using the Donaldson camera. There was significantly less variability of disk analysis using the Nidek 3Dx system than the Donaldson camera (F = 1.6, P = .01, df = 99). Overall mean stereoscopic quality was significantly better with the Nidek system (3.2 +/- 1.15 S.D.) than with the Donaldson camera (2.5 +/- 1.27 S.D., P < .01). Age was the only variable that correlated with stereoscopic quality for both cameras. The new Nidek camera provided significantly better stereoscopic quality images than the Donaldson camera and with significantly more reproducible optic nerve head assessments.

Because mitomycin C reduces the resistance to aqueous outflow normally provided by postoperative subconjunctival fibrosis, we would expect to see more frequent hypotony after trabeculectomy with mitomycin C than after standard trabeculectomy. To evaluate the incidence of hypotony in trabeculectomy with intraoperative mitomycin C use, we performed a retrospective analysis on 52 eyes of 48 patients who underwent trabeculectomy with mitomycin C. Mitomycin C concentration was 0.4 mg/ml in all eyes, and treatment time ranged from 3 1/2 to seven minutes. We defined hypotony as intraocular pressure lower than 5 mm Hg on two examinations at least four weeks apart and six weeks or more postoperatively. Overall, average intraocular pressure was 22.7 +/- 10.7 mm Hg preoperatively and 10.4 +/- 5.0 mm Hg postoperatively (P < .001), a mean reduction in intraocular pressure of 12.3 +/- 11.5 mm Hg (47.0%). Hypotony occurred in 17 of 52 eyes (32.7%). Seven eyes required trabeculectomy revision for hypotony. Hypotonous eyes received longer treatment with mitomycin C intraoperatively, with a mean application time of 5.3 +/- 1.0 minutes for hypotonous eyes and 4.7 +/- 0.8 minutes for nonhypotonous eyes (P = .03). Sixteen of 43 eyes (37.2%) undergoing primary filtration became hypotonous, as compared to one of nine (11.1%) eyes that had previous filtering procedures (chi 2 = 2.30, P = .13). Nine of 17 hypotonous eyes (52.7%) and five of 35 nonhypotonous eyes (14.3%) had loss of two or more lines of Snellen visual acuity. Hypotony occurred in nearly one third of eyes treated with mitomycin C during trabeculectomy in our study. There was a statistically significant (P = .03) association of hypotony with longer application time of mitomycin C, and a trend toward increased incidence of hypotony in primary filtration.

PURPOSE: To investigate the safety and efficacy of holmium YAG laser sclerectomy, a new laser filtration procedure. METHODS: The authors performed holmium YAG laser sclerectomy on 49 eyes of 46 patients (mean follow-up, 12.3 +/- 1.1 months). RESULTS: Mean preoperative intraocular pressure (IOP) was 26.9 +/- 1.3 mmHg; postoperative mean IOP on last follow-up visit was 19.7 +/- 1.6 mmHg. Thirty (61%) of 49 eyes achieved a final IOP of 5 to 22 mmHg, 29 (59%) of 49 had a final IOP of 5 to 19 mmHg, and 21 (43%) of 49 had a final IOP of 5 to 15 mmHg. Sixteen (73%) of 22 eyes treated postoperatively with 5-fluorouracil (5-FU) had a final IOP of 21 mmHg or less. Twenty-seven percent of eyes lost one or more lines of vision, and 36% of eyes gained one or more lines of vision; there was no median change in visual acuity. Complications included suprachoroidal hemorrhage in 7 (14%) of 49 eyes and intraoperative vitreous hemorrhage in 2. Seventeen (35%) of 49 eyes required a second IOP-lowering procedure. CONCLUSION: Holmium YAG laser sclerectomy is an effective means to perform glaucoma filtration surgery. This is a full-thickness filtering procedure, with all of the risks attendant.

The picosecond neodymium:yttrium lithium fluoride laser, a high-power, short-pulse laser that uses low energy per pulse and has a high repetition rate and a highly coherent energy source of 1,053 nm, was used to perform sclerectomies by an ab externo approach in human cadaver eyes. We evaluated laser settings with regard to full-thickness scleral perforation and thermal damage to surrounding tissue. We studied energy per pulse, depth per burst (a present number of spots), spot and line separation of the pattern (spacing between spots of the laser in length [spot separation] and width [line separation]), and total energy required to perforate the sclera. Efficiency was determined by evaluating which settings required the fewest spots and least total energy to perforate the sclera. We studied histologic sections of the sclerectomy sites to determine thermal damage to the surrounding sclera. The picosecond neodymium:yttrium lithium fluoride laser is effective in performing full-thickness sclerectomy with minimal thermal damage to the surrounding tissue. The anterior chamber could be penetrated with an average total energy of 13.3 +/- 0.4 (SEM) J. The sclerectomy size was 545 +/- 11 microns externally and 163 +/- 4 microns internally. Successful sclerectomies were performed with as little as 3 to 5 microns of thermal damage to the surrounding scleral tissue with 250 microJ per pulse.