Purpose: To investigate the stereopsis after single focus intraocular lens (SIOL) implantation in patients aged <40 years with unilateral cataract.
Methods: In total, 36 patients (36 eyes) were divided into emmetropia and myopia groups. Twenty seven subjects with good uncorrected distance visual acuity (UCDVA) after surgery were enrolled in the emmetropia group. The myopia group consisted of 9 subjects whose one eye had mild myopia postoperatively and the other was emmetropic or myopic. Visual acuity, distance and near stereoacuity were measured post-operatively.
Results: In the emmetropia group, uncorrected near visual acuity (UCNVA) did not differ significantly between eyes (t=1.87, P>0.05). The LogMAR UCNVA of the operated and fellow eyes were (0.71±0.12) and (-0.05±0.07, t = 28.4, P<0.001) respectively. Distance stereoacuity was 60"; the near stereoacuity with uncorrected visual acuity and BCNVA in the operated eyes were 200" and 30" respectively (Z=－4.121, P<0.001). In the myopia group, the BCDVA did not differ significantly between the operated and fellow eyes (t =-0.636, P>0.05). The UCNVA of the operated eyes (0.18±0.12) was significantly better compared with that of the fellow eyes (-0.04±0.10, t = 4.2252, P<0.001). The distance stereoacuity with uncorrected visual acuity and BCDVA in the operated eyes were 200" and 60" respectively (Z =-2.371, P<0.05). The near stereoacuity with uncorrected visual acuity was 50".
Conclusion: For patients with unilateral cataract aged <40 years, stereopsis is closely associated with refractive status after IOL implantation. Near stereoacuity in emmetropic eyes can be improved with refraction, and that in mildly myopic eyes can be enhanced by leaving myopia uncorrected.