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Biomedical subjects

Louis D Nichamin

Publications and source records attributed to Louis D Nichamin.

7 recordsLinked to original sources
PubMed2006

Astigmatism control.

Refractive cataract surgery has become a reality for the modern phacosurgeon, and control of astigmatism plays a vital role in this quest for optical refractive outcomes. Fortunately, a number of effective options exist to minimize postoperative cylinder. These include placing the cataract incision on the steep corneal meridians; use of adjunctive corneal or limbal relaxing incisions; or even using advanced technology, such as the excimer laser. Careful attention must be directed to the measurement of pre-existing astigmatism, and a detailed surgical strategy must then be formulated. Finally, one must be able to avail themselves of enhancement techniques to address residual astigmatism.

Astigmatism↗
PubMed2005

Optical performance of 3 intraocular lens designs in the presence of decentration.

PURPOSE: To study the theoretical optical performance of 3 intraocular lens (IOL) designs in the presence of IOL decentration. SETTING: Optics Center, Bausch & Lomb, Rochester, New York, USA. METHODS: A ray-tracing program was used to evaluate the effect of IOL decentration on the optical performance of 3 silicone IOLs (LI61U, Bausch & Lomb; Tecnis Z9000, Advanced Medical Optics; and a new aberration-free IOL [SofPort AO, Bausch & Lomb]) in an experimental model eye. The study was done using pupil diameters of 3.0 mm, 4.0 mm, and 5.0 mm and IOL decentrations of 0 mm, 0.25 mm, 0.50 mm, 0.75 mm, and 1.00 mm. The modulation transfer functions were computed and plotted. A Monte Carlo simulation analysis with 1000 trials with IOL decentration randomly varying for each pupil size was performed. RESULTS: Decentration of LI61U and Tecnis Z9000 IOLs led to asymmetrical higher-order aberrations that adversely affected the optical performance of the model eye; performance was not affected with the aberration-free IOL because it lacks inherent spherical aberration. Optical performance with the aberration-free IOL was better than with the LI61U IOL as the former has less spherical aberration and did not introduce other aberrations when decentered. Performance with the aberration-free IOL was better than with the Tecnis Z9000 IOL for 3.0 mm, 4.0 mm, and 5.0 mm pupils when decentration exceeded 0.15 mm, 0.30 mm, and 0.38 mm, respectively. Performance with the LI61U IOL was better than with the Tecnis Z9000 IOL for 3.0 mm, 4.0 mm, and 5.0 mm pupils when decentration exceeded 0.3 mm, 0.5 mm, and 0.5 mm, respectively. Monte Carlo simulations showed the expected postoperative results of the LI61U IOL and aberration-free IOL would be repeatable and predictable, whereas the outcomes with the Tecnis Z9000 IOL would vary widely. CONCLUSIONS: The optical performance of the model eye was not affected by decentration of an aspheric IOL designed to have no inherent spherical aberration. With decentration, the performance with the new IOL was better than with a conventional spherical IOL and an aspheric IOL designed to offset the spherical aberration of an average cornea.

Biocompatible Materials↗
PubMed2003

Treating astigmatism at the time of cataract surgery.

An increasingly important goal of modern cataract and implant surgery is to obtain the most desirable refractive outcome for our patients, and in so doing, decrease their dependence upon spectacle correction. Refined spherical outcomes are now achieved by directing close attention to biometry technique, through the use of third generation intraocular lens (IOL) power formulae, and refinements in technology such as partial coherence interferometry. Similarly, improvements in astigmatic outcomes are now possible by focusing upon and obtaining more accurate preoperative cylinder measurements, careful surgical planning particularly in regard to incision(s) design, use of toric IOLs, and employing advanced postoperative enhancement techniques. Because of these refinements in technique and technology, the field of cataract and implant surgery has emerged as a true and recognized form of refractive surgery.

Astigmatism↗