PURPOSE To study the relationships between the refractive power of the crystalline lens, overall refractive error of the eye, and degree of nuclear cataract. METHODS All phakic participants of the population-based Central India Eye and Medical Study with an age of 50+ years were included. Calculation of the refractive lens power was based on distance noncycloplegic refractive error, corneal r...

Purpose To evaluate the accuracy of IOL power calculation using adjusted corneal power according to the posterior/anterior corneal curvature radii ratio. Methods Nine hundred twenty-eight eyes from 928 reference subjects and 158 eyes from 158 cataract patients who underwent phacoemulsification surgery were enrolled. Adjusted corneal power of cataract patients was calculated using the fictitio...

Intraocular lens (IOL) power calculations are known to be difficult in eyes that have had corneal refractive surgery and several methods have been proposed to estimate IOL power. Among the methods not requiring preoperative data, the apahakic refraction technique has been successfully used to calculate IOL power in post-refractive cases and other conditions that cause unreliability in standard ...

AIM To compare postoperative keratometric corneal refractive changes after phacoemulsification surgery between pre-incision and single stepped clear corneal incision techniques. PATIENTS AND METHODS This prospective clinical study included 40 eyes of 40 patients who underwent clear corneal cataract surgery. Twenty eyes were operated using pre-incision technique (Group A), and 20 eyes using si...

In the optical system of the human eye, total refractive power consists mainly of corneal and lenticular components. Approximately two-thirds of the eye's converging power is at the air–cornea (tear film) interface; one-third is in the lens. Total corneal power is determined by corneal anterior and posterior curvature, corneal thickness, and the corneal refractive indices. Traditionally, anteri...

Heritability estimates for corneal power were found to be high and similar for two populations which differed in their incidence of esotropia. This similarity suggest (1) that genetic differences for corneal power do not contribute to the difference in heritability for spherical refractive error reported for these populations and (2) that this character is not a critical variable contributing t...

PURPOSE To quantify the error introduced by videokeratographic corneal topography devices in using a paraxial formula to calculate power over the entire corneal surface, including areas removed from the central paraxial region where the formula is known to be invalid. METHODS Corneal refractive power and two paraxial power approximations were computed as a function of distance from the apex f...

To evaluate the ability of assessing the refractive change induced by myopic laser surgery using the intrinsic data, obtained from a reference intrinsic to the cornea. Twenty-nine eyes with laser in situ keratomileusis for myopia were included in the study. Statistical analyses were performed to determine the relationship between refractive changes and two kinds of corneal power: KIP_value (obt...

Results of intraocular lens power calculation were lower than actual required power in eyes with previous corneal refractive surgery because the inaccurate readings of corneal power obtained from standard keratometry. This causes the unacceptable hyperopia after cataract surgery. With increasing of population undergone excimer laser refractive surgery, this problem will be an obvious problem in...

The porcine eye is often used as an ex vivo animal model in ophthalmological research. It is well suited for investigations concerning refractive surgery; however, corneal topography data are scarce. This study investigated the corneal topography and pachymetry of the porcine eye to provide further reproducible data. We evaluated freshly enucleated porcine eyes (n = 16) by performing computeriz...