The routine use of topical anesthesia for cataract surgery appears to be safe, inducing yearly endothelial cell count reductions comparable with those seen in healthy eyes not undergoing the operation.
Monza, Italy-The routine use of topical anesthesia for cataract surgery appears to be safe, inducing yearly endothelial cell count reductions comparable with those seen in healthy eyes not undergoing the operation, according to Matteo Piovella, MD, director, Centro Microchirurgia Ambulatoriale, Monza, Italy.
"Cataract surgery is the main surgery in ophthalmic practice, and it is very well known that we can get intraoperative endothelial damage," said Dr. Piovella. Damage can result from contact with surgical instruments in the posterior part of the cornea and from free radical formation caused by the interaction of chemicals in irrigation fluids with ultrasound, he added.
He discussed the results of a retrospective evaluation of 104 eyes in 69 patients who underwent phaco with 2% lidocaine topical anesthesia. Patients were followed for 9 years.
Foldable or rigid IOLs were implanted via a 3.2-mm three-step temporal clear-corneal incision. Ten models of lenses were used. Mean duration of the surgery was 14 minutes, and mean ultrasound time was about 1 minute, 45 seconds.
"It is important to remember that all of these data are related to a surgery that was performed 10 years ago-so with the technology of 10 years ago and with the knowledge of 10 years ago," Dr. Piovella noted.
Postoperatively, the study cases were described as uneventful and showed no Tyndall effect or corneal edema at day 7 or later. Patients underwent complete ophthalmologic examination after years 1, 2, 4, and 9. Using Student's t test for paired samples, researchers compared endothelial cells obtained in the central cornea preoperatively using a clinical, automatic, noncontact specular microscope (Noncon Robo-CA, Konan) with those obtained at the follow-up intervals.
Best spectacle-corrected visual acuity and the spherical equivalent remained relatively stable over the 9-year period, he said.
Preoperatively, the mean endothelial cell count was 2,422 ± 431 cells/mm2 . The decrease in endothelial cell count was 5.73% after 1 year, 5.13% at 2 years, 7.44% at 4 years, and 8.08% at 9 years. In year 9, the mean endothelial cell count was 2,212 cells/mm2 .
The eyes that underwent phaco with topical anesthesia experienced a yearly endothelial cell loss of 0.97%, with an annual loss of 0.3% after year 1. Research by Bourne has shown that the endothelial cell loss in healthy eyes that have not undergone cataract surgery averages 0.6% per year (range, 0.3% to 1%), Dr. Piovella noted.
"Nowadays, we have earlier-in-life cataract surgery, and the surgical goal is achieving limited postoperative endothelial cell loss and maintaining yearly loss similar to natural, age-related decrease," Dr. Piovella noted.
Research that he and colleagues presented at the American Academy of Ophthalmology annual meetings in 1995 and 1996, as well as the results of studies by Galin and Dick, have demonstrated the importance of managing endothelial cell loss within the first year after cataract surgery, he said.
Reducing the surgical time can limit endothelial damage, and choosing the proper viscoelastic and using it correctly also can help preserve endothelial cells, he said.
Intraoperative trauma could lead to mild central cornea edema on the first postoperative day that may indicate a 35% reduction in endothelial cells, Dr. Piovella said, based on a separate study of 24 eyes in 21 patients that he conducted. Mean surgical time was 21 minutes, and mean phaco time was more than 2.5 minutes.
"I found a loss of 0.55%, with a standard deviation of 25 cells/mm2 ," he said.