ABSTRACT
PURPOSE: To assess photopic and mesopic vision in patients implanted with the Bi-Flex® M 677 MY bifocal intraocular lens (IOL). METHODS: In this prospective clinical study, 25 patients with cataract in both eyes were subjected to cataract surgery and bilateral implantation of the Bi-Flex® M 677MY (Medicontur, Hungary) IOL. Three months after surgery, high-contrast photopic uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) were determined. Intermediate at 65 cm (DCIVA) and near at 40 cm (DCNVA) visual acuity were also measured, both with best distance correction. The CSV-1000 test chart was used to assess contrast sensitivity (CS). Defocus curves were constructed under photopic and mesopic conditions, determining binocular best-corrected visual acuity over the range +1.50 D to -4.00 D in 0.50-D steps. A KR-1W Wavefront Analyzer was used to measure pupil size and aberrometric outcomes. Presence and type of dysphotopsia were evaluated with the Likert scale. RESULTS: Mesopic mean pupil diameter was 4.58 ± 0.73 mm. The mean values at 3 months were UDVA 0.03 ± 0.09, CDVA -0.05 ± 0.06, DCIVA 0.20 ± 0.07, and DCNVA 0.11 ± 0.08. Mean CS for the 4 frequencies examined were 1.66 ± 0.16, 1.75 ± 0.14, 1.39 ± 0.22, and 0.96 ± 0.19. Significant differences were observed in defocus curves for photopic and mesopic conditions. A significant correlation between pupil diameter and the dysphotopic photopic was found (r = 0.62; p = 0.02). CONCLUSIONS: The evaluated progressive apodized diffractive design IOL provides effective restoration of visual function in far and near vision distance with an adequate intermediate visual quality between -1.00 and -1.50 focus.
Subject(s)
Color Vision/physiology , Lens Implantation, Intraocular , Mesopic Vision/physiology , Multifocal Intraocular Lenses , Phacoemulsification , Pseudophakia/physiopathology , Aged , Aged, 80 and over , Contrast Sensitivity/physiology , Female , Humans , Male , Middle Aged , Prospective Studies , Prosthesis Design , Pupil/physiology , Visual Acuity/physiologyABSTRACT
PURPOSE: This study was designed to establish variations in the biometry of the ocular globe according to refractive state, and to determine the extent to which these characteristics contribute to the appearance and degree of myopia. METHODS: Subjects recruited for the study were 583 university students of mean age 20.32 +/- 2.82 years. Objective refraction without cycloplegia and the corneal radius (CR) of curvature were determined using an autokeratorefractometer. The axial length (AL) of the eye was measured by ultrasound biometry. The population was then characterized according to these three variables to establish relationships among them. Data were stratified by both refractive state and age of onset of myopia. RESULTS: The prevalence of myopia (more minus than 0.50 D) was 57.78%; half the refractive defects being less minus than -3.00 D. The AL of the eye was found to be more related to the refractive error than the CR, especially in subjects with moderate myopia. In emmetropes or subjects with low myopia, the CR was directly correlated with AL, although this correlation was somewhat diminished in moderate myopias. Nonetheless, in the latter and in juvenile-onset myopia, a trend towards a shorter radius of curvature was observed. CONCLUSIONS: The AL of the eye is the main morphological variable related to myopia. The function of the cornea seems to compensate the possible myopizing effects of slight increases in AL. When increases in AL are excessive, this effect of the cornea tends to disappear.
