Square and near-square incisions help prevent hypotony

Clear corneal wounds with square or nearly square surface architecture that are meticulously checked for incisional sealing are stable postoperatively, as demonstrated by the absence of hypotony and wound leakage. In a sealed clear corneal wound, IOP remains reasonably stable relative to the level set at the conclusion of the procedure, according to Shaleen Belani, MD, from Advanced Vision Care, Los Angeles.

Previous research has indicated that square incisions are more stable and more resistant to external deformation compared with rectangular incisions, she said. Besides shape, other factors that affect the wound construction are IOP, blade sharpness, substantial tissue rigidity, and the surgeon.

To address the question of proper wound construction after clear corneal incision cataract surgery, Dr. Belani and co-author Samuel Masket, MD, evaluated 2.2- and 3-mm clear corneal cataract incisions with square or nearly square surface architecture for stability. Investigators retrospectively reviewed the charts of 60 patients who had undergone clear corneal cataract extraction from January to September 2006. A square 2.2-mm incision had been used in 50 patients and a nearly square 3-mm incision had been used in 10 patients.

Mean IOP level postoperatively in the 50 eyes with a 2.2-mm square incision was 19.2 mm Hg and in the 10 eyes with a 3-mm nearly square incision the mean IOP was 16.6 mm Hg. No patient had an IOP less than 10 mm Hg. There was no hypotony or wound leakage in any patient, Dr. Belani reported.

"The IOP level early after surgery is a valid marker of wound stability," Dr. Belani reported. "An incompetent, poorly constructed clear corneal incision may be associated with hypotony, leakage, and an increased infection rate. Careful wound construction with appropriate architecture, square wound construction, should reduce this tendency."