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Monovision and Asphericity With Light Adjustable Intraocular Lenses


Purpose: : To produce and evaluate monovision and aspheric-extended depth of focus, in patients implanted bilaterally with light adjustable intraocular lenses (LALs).

Methods: : Thirteen cataract patients were implanted bilaterally with LALs (Calhoun Vision, Pasadena, USA). Two weeks after surgery, the lenses were irradiated through the cornea with the appropriate spatial intensity profile to correct the patient’s astigmatism and to leave the desired value of defocus. The surgery and the light treatments were performed first in one eye (the one set for nearly zero defocus) and a few months later on the fellow eye (the one set for mild myopia). Five of the patients were also treated with aspheric light adjustments to induce additional depth of focus. Wavefront-guided refraction was determined for every eye during the entire adjustment process. Visual acuity (VA) was measured using a computer-assisted procedure both monocularly (each eye separately) and binocularly. All the VA measurements were performed for letters projected on a microdisplay placed at 10 m, 60 cm, 40 cm and 30 cm.

Results: : In the eight patients treated for pure monovision the eye intended for far vision displayed a residual defocus between -0.75-D and 0 D, and the eyes intended for near vision were between -1.75-D and -2.25-D. For the distance eye, the monocular uncorrected distance VA was on average 0.9 for far, decreasing to around 0.5 at 30 cm. The eyes targeted for near vision had an average distance VA of 0.35 increasing to 0.8 for 40 cm. The measured binocular VA was on average 0.9 for 10 m, 0.8 for 40 cm and 0.7 for 30 cm. At the end of the treatments process, every patient was spectacle independent and did not report any adverse effect. In the five subjects treated with aspheric adjustments, spherical aberration was around -0.1 microns for a 4-mm pupil diameter. The eyes of these subjects intended for near vision had a residual defocus between -0.5 and -1.0 D, with an average VA of 0.8 for both 10 m and 40 cm.

Conclusions: : The use of the LALs as an advanced and fully customized new approach to perform monovision in cataract patients was demonstrated. The LALs provide the ability to effectively set the final, desired refraction for each eye and can be reversed to emmetropia, in the event it is poorly tolerated by the patient. This approach offers a significantly improved version of standard monovision that assures good compromises of quality of vision and spectacle independence to the patients. As a combined alternative, aspheric adjustments which increase depth of focus may improve monovision performance.

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