Accuracy of intraocular lens power estimation in eyes having phacovitrectomy for macular holes.

Purpose: To report the accuracy of intraocular lens (IOL) power estimation in eyes having combined phacoemulsification and vitrectomy for macular holes and to compare the axial length (AL) in those eyes with that in the fellow eyes.

Setting: Calderdale Royal Hospital, Halifax, West Yorkshire, United Kingdom.

Method: The mean and standard deviation of the refractive aim, achieved refraction, and postoperative prediction error (calculated as difference between achieved refraction and refractive aim) were determined in 40 patients who had phacovitrectomy with gas tamponade for the treatment of idiopathic macular holes. The percentage of patients with an achieved refraction within +/-0.50 diopter (D), +/-1.00 D, and more than 2.00 D of the refractive aim was recorded. The mean absolute error (MAE) of the postoperative prediction error was calculated. In addition, the AL in eyes with macular holes was compared with that in fellow eyes. Axial lengths were measured using applanation A-scan ultrasound.

Results: Of eyes having phacovitrectomy, 45.0%, 67.5%, and 90.0% achieved a postoperative refraction within +/-0.50 D, +/-1.00 D, and +/-2.00 D, respectively, of the refractive aim; 10.0% of eyes were more than -2.00 D from the refractive aim. The overall postoperative prediction error ranged from +1.64 D to -2.51 D. The mean refractive aim was +0.30 +/- 0.72 D and the mean achieved refraction, -0.09 +/-1.25 D. There was no clinically significant difference between the means. The mean postoperative prediction error was -0.39 +/- 1.01 D, suggesting a myopic overcorrection occurred postoperatively. The MAE of the postoperative prediction error was 0.83 D. The mean AL was 23.40 mm in operated eyes and 23.46 mm in fellow eyes.

Conclusions: The achieved refraction after phacovitrectomy for macular holes was comparable to results after phacoemulsification alone. The myopic overcorrection after phacovitrectomy might be a result of the gas bubble causing forward displacement of the capsular bag and IOL or inaccuracies in AL and keratometry measurements. Aiming for residual hyperopia may counteract the overcorrection. There was no difference in AL between eyes with macular holes and fellow eyes.