Relative anterior microphthalmos poses challenges in cataract surgery

Relative anterior microphthalmos can pose significant intraoperative challenges in cataract surgery, a study found. The surgical difficulties encountered in the study were attributed to the reduced working space in the small anterior chambers in these eyes, the study authors said.

Bharti R. Nihalani, MS, and colleagues at the Raghudeep Eye Clinic in Ahmedabad, India, evaluated 1,400 patients undergoing cataract surgery to determine the prevalence of relative anterior microphthalmos (RAM), defined as a horizontal corneal diameter of 11 mm or less and an anterior chamber depth of 2.2 mm or less in an eye with axial length of greater than 20 mm.

The horizontal corneal diameter was measured with calipers; the anterior chamber depth and axial length were measured with immersion ultrasound.

Among the 1,400 eyes, RAM was identified in 84 (6%). Two control groups with the same number of subjects were created for comparison. One group consisted of 84 subjects with horizontal corneal diameter of more than 11 mm, anterior chamber depth of more than 2.2 mm and axial length of more than 20 mm. A second control group of 84 subjects had horizontal corneal diameters of 11 mm or less, anterior chamber depths of more than 2.2 mm and axial lengths of more than 20 mm.

Intraoperative performance of the surgeon and postoperative outcomes were analyzed for the control groups and the RAM subjects.

The study found that RAM was associated with the presence of small pupil in 34 patients (41%), corneal guttae in 31 (37%); glaucoma in 29 (35%) and pseudoexfoliation in six (7%). Intraoperatively, RAM was associated with overall surgical difficulty because of less working space in 59 eyes compared with the control groups. Uveal trauma occurred in 12 eyes (14%), Descemet’s membrane detachment in five (6%) and posterior capsular rupture in two (2%).

Postoperatively, RAM was associated with transient corneal edema in 63 eyes on the first postoperative day. Postoperative edema cleared within 1 week of surgery, the authors said. None of the eyes developed corneal decompensation, nor did the researchers find significant uveal inflammatory response in the eyes.

“We found that RAM is not an uncommon condition,” the researchers said. “It is only that it is not recognized preoperatively by most cataract surgeons.”

The researchers said that eyes with RAM “pose a significant challenge” during phaco because of the shallow anterior chamber and a smaller working space created by the small corneal diameter.

“All intraoperative complications, including posterior capsule rupture, could be attributed to less working space,” they said.

The study is published in the August issue of Ophthalmology.