Comparisons of postoperative uncorrected visual acuity of spherical and aspheric Toric intraocular lens implantation

Abstract:

AIM: To evaluate the uncorrected visual acuity after implantation of spherical astigmatism intraocular lens(IOL)and aspheric astigmatism intraocular lens in cataract surgery of patients with preoperative corneal astigmatism.

METHODS: Fifty-seven eyes of 44 patients were divided into two groups according to Toric intraocular lens types: spherical group with 23 patients(27 eyes), aspheric group with 21 patients(30 eyes). Uncorrected distance visual acuity(UDVA)preoperatively and at postoperative 1d, preoperative corneal astigmatism, intraocular lens type and spherical equivalent, IOL cylinder axis position were recorded. We compared the two groups of uncorrected distance logMAR visual acuity visual differences at preoperative and postoperative 1d and calculated the proportion of patients with UDVA over 0.4 at postoperative 1d, then divided patients into two layers in accordance with astigmatism degree with less than 2.0D as low astigmatism layer and more than 2.0D as high astigmatism layer and compared the improving effect of two groups of postoperative UDVA according to the preoperative corneal astigmatism.

RESULTS: In spherical and aspheric group, the rate of patients at postoperative 1d with UDVA better than 0.4 were 92.6% and 93.3%, which were significantly increased compared with preoperative 14.8% and 13.3% respectively. The LogMAR UDVA of two groups at postoperative 1d compared with preoperative were significantly improved, and the differences were statistically significant(P<0.01). There was no significant difference in LogMAR UDVA at preoperative and postoperative 1d between two groups(P>0.05). Within every astigmatism layer, there was no statistical significance between two intraocular lens in improved degree of the postoperative UDVA(P>0.05); the LogMAR UDVA of every group at postoperative 1d compared with its preoperative were significantly improved, the difference was statistically significant(P<0.01). Within every group, the difference of improving effect of postoperative UDVA between different preoperative astigmatism had no statistical significance(P>0.05); the LogMAR UDVA of every layer at postoperative 1d compared with its preoperative were significantly improved, the difference was statistically significant(P<0.01).

CONCLUSION: Spherical and aspheric Toric IOL implantation can both effectively improve the UDVA in cataract surgery of patients with preoperative corneal astigmatism. But in terms of improving the UDVA, aspheric Toric intraocular lens is not better than that of spherical.

Key words:cataract; corneal astigmatism; Toric intraocular lens; spherical; aspheric