Gradient refractive index optics IOL: Theoretical background and clinical results

Abstract

Purpose:To present the theoretical optical background and clinical results of a new multifocal intraocular lens (MIOL) concept–gradient refractive index optics (Gradiol).Patients and Methods:Original mathematical modeling software was used to calculate optimal construction of the MIOL optic constructed from two polymer materials with different refractive indices. Gradiol lenses were manufactured from hydrophobic acrylic utilizing original step-by-step polymerization technology with the final power difference of of 3.5 D between optic components. Non-comparative prospective clinical study included 26 patients (29 eyes) who were candidates for MIOL implantation. All surgeries were performed at the S. Fyodorov Eye Microsurgery Complex State Institution, Moscow, Russia. After implantation of the Gradiol lenses, the postoperative evaluations included distance (best corrected visual acuity (BCVA)) and near visual acuity (NVA), contrast sensitivity (CS), and amplitude of pseudoaccommodation. Subjective patient's satisfaction was assessed using a questionnaire (VF-14).Results:The mean age of the patients was 62.5 ± 5.7 years (range 27-82 years). All surgical procedures were uneventful. At 6 months postoperatively, the mean uncorrected distance VA was 0.73 ± 0.18, mean uncorrected near VA was 0.57 ± 0.19, mean corrected distance VA was 0.89 ± 0.15, mean corrected near VA was 0.84 ± 0.07, and amplitude of pseudoaccommodation was 4.75 ± 0.5 D. Eighty-six percent of patients were spectacle independent for daily activities and reading. Optical disturbances that were functionally significant were reported by 10.7% of patients postoperatively.Conclusion:The clinical outcomes of this study confirmed the theoretical calculations of constructing MIOL optics from materials with different refractive indices.

Current State of the Art and Next Generation of Materials for a Customized IntraOcular Lens according to a Patient-Specific Eye Power

“…Another class of materials consists of materials known by the acronym GRIN (GRadient INdex—with variable refractive index). Ophthalmic lenses could be made with such materials that make greater use of the variation in the refractive index rather than the curvature to optimally direct the light onto the retina [ 69 , 70 ]. A traditional lens designer can vary the curvatures, the thickness, and the refractive index of the material.…”

“…GRIN-MIOLs’ main advantage is determined by the gradient optics obtained by changing the refractive index in the inner structure of the IOL. In this way, optical side effects are diminished, also improving functional results [ 69 ]. Nevertheless, gradient IOLs show some advantages compared to MIOL design, such as mimicking normal physiology; a smooth optical surface that allows to decrease the mechanical damage to the lens optic during implantation; postoperative better retinal image quality; and functional vision achieved at near and intermediate distances and under varying light conditions (photopic, mesopic, and scotopic).…”

Compuestos de PMMA y Nanopartículas de TiO2 para posibles aplicaciones Ópticas

“…Propone que esta condición ocurre debido a cambios en el índice de refracción promedio equivalente, y la tasa de crecimiento anual del lente cristalino natural del ojo [1]. En esta idea es el principio en el que se basan los diferentes tipos de lentes.…”