ectoderm before the fourth week of gestation could account for the brain, skull, and ocular abnormalities. The nevus sebaceous itself may reflect abnormal ectodermal development at a later stage of embryonic life with mesenchymal cells displaced during closure of the facial fissure accounting for differentiation into cartilage and bone.—Thomas J. Liesegang

♦Wills Eye Hospital, Ninth & Walnut Sts, Philadelphia, PA 19107.

• The use of computerized videokeratography as an aid in fitting rigid gas permeable contact lenses. Donshik PC*, Reisner DS, Luistro AE. Trans Am Ophthalmol Soc 1996;94:135-145.

SOFTWARE PROGRAMS ARE AVAILABLE THAT CAN DE-

termine the parameters of rigid gas-permeable contact lenses from videokeratography images and also allow one to study simulated fluorescein patterns. The authors assessed the efficacy of EyeSys computer­ized corneal topography in fitting cosmetic rigid gas-permeable contact lenses on normal corneas and in patients who have keratoconus. Thirteen patients were fit initially with a cosmetic rigid gas-permeable lens chosen on the basis of corneal topography using the EyeSys videokeratoscope and contact lens soft­ware. Thirteen control patients were fitted with a cosmetic rigid gas-permeable contact lenses by means of diagnostic contact lenses. In 38% of patients fitted using the corneal topography program, the first lens chosen was correct, with no additional changes in lens parameters required. In the remaining 62%, 21 parameter changes were required. In the group fit initially with diagnostic lenses, 53% required no additional change parameters from the original con­tact lens. In the remaining 47%, 12 parameter changes were required. In the keratoconus group, retrospective videokeratography data were analyzed from multiple points in patients who were successfully fit with a rigid gas-permeable lens. The final base curve of the patient's rigid gas-permeable lenses were correlated most closely with the average flat corneal curvature at the 3-mm central zone. The authors conclude that fitting cosmetic rigid gas-permeable contact lenses with the EyeSys videokeratography and

software was inferior to diagnostic lenses. In patients with irregular corneas, corneal topography was help­ful in determining the initial base curve of the contact lens; in patients with keratoconus, it appears to be the average flat corneal curvature at the 3.0 mm zone.—Thomas J. Liesegang

Twenty-nine North Main St, West Hartford, CT 06107.

• Long-term results of trabeculectomy in eyes that were initially successful. Wilensky JT*, Chen TC. Trans Am Ophthalmol Soc 1996;94:147-164.

THERE IS LITTLE PUBLISHED INFORMATION REGARD-

ing outcomes of glaucoma filtering surgery beyond 10 years. In this retrospective study, the authors identified 40 patients who had successful primary trabeculectomy surgery at 1 year and were available for follow-up 10 years later. Twenty-four of the 40 patients were black; antimetabolites were not used. With respect to intraocular pressure (IOP) control, 83% were still considered to be successful at 5 years, 73% at 10 years, but only 42% at 15 years. Ten percent required additional glaucoma surgery by 5 years, 25% by 10 years, and 58% by 15 years. Forty percent of the eyes had cataract surgery by the time of the last follow-up examination. If adequate control of IOP is achieved at 1 year, control tends to remain for up to 10 years, after which successful control is difficult to maintain without reoperation in over half of the patients. There was a small percentage of patients with successful control of IOP but without control of disease progression. Trabeculectomy was associated with a decrease in the number of medica­tions needed to control disease progression. Trabecu­lectomy was associated with subsequent cataract ex­traction in 40% of patients and with stable visual acuity in up to two-thirds of patients at last follow-up. There can be loss of IOP control after cataract extraction, which may necessitate additional glauco­ma surgery.—Thomas J. Liesegang

"University of Illinois Chicago Eye Center, 1855 West Taylor St, Chicago, IL 60612.

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