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Susana Marcos, Sergio Barbero, Lourdes Llorente, Carlos Dorronsoro, Patricia Rosales, Ignacio Jiménez-Alfaro; Optical aberrations with aspheric intraocular lenses. Journal of Vision 2003;3(12):39. doi: 10.1167/3.12.39.
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Purpose: In a cataract procedure the crystalline lens is replaced by an Intraocular Lens (IOL), modifying the corneal (by the incision) and the internal aberration pattern (by the IOL). We studied ocular optical quality in patients with aspheric (Tecnis, Pharmacia) IOLs. We measured the change of corneal aberrations with cataract surgery and the aberrations of the aspheric IOLs in vivo.
Methods: Corneal and total aberrations were measured on 10 eyes before and after phacoemulsification with aspheric IOL implantation. Corneal aberrations were measured using corneal elevation from corneal topography and custom software. Total aberrations were measured with a 2nd-generation custom-made laser ray tracing (LRT). Sampling pupil diameters ranged from 4.5 to 6-mm, centered at the natural pupil. Decentration of the IOL was assessed from images captured by the back-illumination channel of the LRT system.
Results: 1) The mean corneal spherical aberration (S.A) after surgery was 0.12±0.15 microns, the mean internal S.A. was −0.18±0.19 microns, and mean post-operative total S.A. was −0.01±0.05 microns. Unlike spherical IOLs (with positive S.A)1, aspheric IOLs tend to balance the corneal S.A., producing total S.A. closer to a younger eye. 2) Third-order aberrations (0.33±0.17 microns) are higher than those reported for younger eyes. Vertical coma is highly correlated with vertical decentrations. 3) Corneal aberrations increase significantly after surgery, particularly astigmatism and trefoil. This increase must be associated with the incision and the implantation procedure.
Conclusions: Aspheric IOLs are effective at compensating corneal spherical aberration. However, optical quality with aspheric IOLs is lower than in young eyes (mainly due to third order aberrations caused by IOL tilt and decentration, and increased corneal aberrations). On average, 3rd order and higher aberrations are lower with aspheric than with spherical IOLs, but overall image quality (including astigmatism) is not significantly different between both type of lenses.
BarberoS.MarcosS.Jiménez-AlfaroI.. “Optical aberrations of intraocular lenses measured in vivo and in vitro”. Journal of the Optical Society of America. In press (2003)
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