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Scleral tunnel may be safer than clear corneal wound
Clear corneal incisions may be a risk factor for endophthalmitis, study shows.
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ST. LOUIS — Clear corneal incisions were associated with a higher rate of postcataract endophthalmitis than scleral tunnel incisions in a study here. The scleral site may be the safer choice, the study authors said.
“When compared to scleral tunnel incisions, clear corneal incisions were found to be a statistically significant risk factor for acute postcataract surgery endophthalmitis,” said George Bohigian, MD, in practice here.
Dr. Bohigian, Nancy M. Holekamp, MD, and Blake A. Cooper, MD, from the department of ophthalmology and visual sciences at the Washington University School of Medicine in St. Louis, compared the incidence of postcataract surgery endophthalmitis when two types of incisions were used.
A retrospective, case-controlled study of all culture-positive endophthalmitis cases following cataract surgery was performed. Dr. Bohigian said the procedures were studied at a tertiary referral center from January 1997 through December 2000 in St. Louis.
Control group in the community
“A control group was established by studying the practice pattern of types of wound closures used in the referring community during the same time period,” Dr. Bohigian said.
Investigators identified 38 cases of culture-positive endophthalmitis over the 4-year period of this study. “The types and distribution of bacteria is as one would expect,” Dr. Bohigian said. “Staphylococcus organisms were found in about 87% of patients in this cohort of 38 eyes.”
Of the cohort, 45% or 17 had clear corneal incisions and 55% or 21 had scleral tunnel incisions. “We further broke it down into stitch and no-stitch techniques,” he said.
Dr. Bohigian said 371 operative reports of cataract surgery were randomly selected from various surgical centers in the community as a control group.
“We found that during that 4-year period, 20% or 76 cases were clear corneal, and about 80% or 95 cases were scleral tunnel, again broken down into stitch and no stitch,” he said.
Disproportionately seen
“Endophthalmitis was seen in a disproportionately higher number of clear corneal incision cases versus the control base of the community practice pattern,” Dr. Bohigian said. Even though the ratio of clear corneal incision to scleral tunnel was close to 1:4, the incidence of endophthalmitis was almost 1:1.
“The relative risk of endophthalmitis was higher in patients with clear corneal versus a scleral tunnel incision,” Dr. Bohigian said. When compared to a scleral tunnel incision, a clear corneal incision was found to be a risk factor for developing endophthalmitis (P = .0017). Dr. Bohigian added that the results indicated that the presence of a stitch did not have an effect on the risk of endophthalmitis.
Identify risk factors
“As a case-controlled study, our work was not intended so much as to report incidence of endophthalmitis but rather to try to identify risk factors,” Dr. Bohigian said.
“There is an increasing preference for clear corneal incision over scleral tunnel incisions. Whenever a new surgical technique is introduced, a learning curve is experienced by the surgeons.”
Hypothetically, he continued, many factors associated with clear corneal incisions could cause the higher risk. There may be more abnormalities associated with clear corneal procedures, he said, or perhaps it may be technically more difficult to do a stable incision in the cornea than the sclera.
For Your Information:
- George Bohigian, MD, can be reached at 450 N. New Ballas Road, Suite 201, St. Louis, MO 63141; (314) 569-1155; fax: (314) 569-3208.