this study was conducted to define the prevalence and types of corneal astigmatism in relation with corneal optical power, axial length, sex and patient age. 641 cataract patients were included in a descriptive study. complete eye examinations were included in a descriptive study. complete eye examinations were performed. the data were analysed by standard procedures including analysis of varia...

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...

purpose: to evaluate the correlation between corneal power and corneal horizontal white to white diameter in myopic patients scheduled for lasik surgery. methods: overall, in 840 eyes of 420 myopic subjects scheduled for lasik, horizontal white to white diameter and mean corneal power were obtained using orbscan ii. pearson correlation test and regression analysis were used to detect any correl...

PURPOSE To investigate the refractive status and optical components of premature babies with or without retinopathy of prematurity (ROP) at 3-4 years old, and to explore the influence of prematurity and ROP on the refractive status and optical components. METHODS Premature babies receiving fundus examination were recruited into ROP group and non-ROP group, with age-matched full-term babies as...

We present a method, termed distributed scanning OCT (DSOCT), which reduces the effects of patient motion on corneal biometry utilizing current-generation clinically available spectral domain optical coherence tomography (SDOCT) systems. We first performed a pilot study of the power spectrum of normal patient axial eye motion based on repeated (M-mode) SDOCT. Using DSOCT to reduce the effects o...

Formulas For Intraocular lens Power calculatIon Modern cataract surgery replaces the natural lens of the eye with an intraocular lens (IOL). After surgery, the optical system of the eye will consist of two major refractive elements, the cornea and the newly inserted IOL. This two-lens system is at the basis of IOL power calculation. To facilitate calculations, both the cornea and the IOL are co...

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 ...

PURPOSE To compare the repeatability and reproducibility of ocular biometry and intraocular lens (IOL) power obtained with a new optical biometer (AL-Scan) and a standard optical biometer (IOLMaster 500). SETTING Siriraj Hospital, Mahidol University, Bangkok, Thailand. DESIGN Prospective comparative study. METHODS Two independent operators measured eyes with cataract using both biometers....