Maximizing depth of field

February 15, 2011

Patients can achieve adequate uncorrected far and near vision with an increase of the depth of field with Q-adjustment and monovision.

Tanta, Egypt-Patients can achieve adequate uncorrected far and near vision with an increase of the depth of field with Q-adjustment and monovision.

Dr. Khalifa and his colleagues conducted a study in which they evaluated modifications of the corneal asphericity and monovision correction in patients with myopia and hyperopia with the aspheric ablation profile and custom-Q adjustments in the correction of presbyopia. A total of 56 patients (112 eyes) were included; 32 patients had hyperopia and 24 patients had myopia.

Preoperative and postoperative corrected and uncorrected near and distance visual acuity levels were evaluated in all patients monocularly and binocularly. The mesopic contrast sensitivity and higher-order aberrations were measured in all patients.

Patients were followed for 3 months and were surveyed regarding their level of satisfaction with the procedure and dependence on glasses.

Dr. Khalifa discussed the highlights of the results. The mean postoperative uncorrected distance visual acuity levels in the patients with hyperopia improved from 0.6 to 0.9 and improved from 0.5 to 0.9 for the patients with myopia. The best-corrected distance visual acuity did not change in the patients with hyperopia, but the patients with myopia lost a mean of 1 line of vision.

Uncorrected near visual acuity in patients with hyperopia improved from 0.4 preoperatively to 1.2 postoperatively. In patients with myopia, however, vision decreased from 0.9 preoperatively to 0.8 postoperatively, Dr. Khalifa said.

"Among the patients with myopia, three eyes lost 2 lines of best-corrected vision and eight eyes lost 1 line of best-corrected vision," he said. "No lines of vision were lost among the [patients with] hyperopia."

The mean higher-order aberration did not change significantly in either group. The mean spherical aberration, however, shifted significantly to the negative side in both groups.

Patient satisfaction with the far and near visual function was not surprisingly lower among the patients with myopia than among the patients with hyperopia, 86% and 100%, respectively, according to Dr. Khalifa.

The mesopic contrast sensitivity improved significantly in the eyes of patients with hyperopia and did not change in the eyes of patients with myopia.