نتایج جستجو برای: corneal optical power

تعداد نتایج: 761214  

Journal: :Investigative ophthalmology 1975
A J Mash J P Hegmann B E Spivey

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...

Journal: :journal of current ophthalmology 0
سیدمحمدرضا طاهری seyed-mohammad-reza taheri آزیتا خیلتاش azita kheiltash

purpose : to compare results of different methods for true corneal power determination and intraocular lens (iol) power calculation formulas in 10 eyes of 7 patients with previous radial keratotomy (rk) with or without astigmatic keratotomy methods : in this case series study, we determined the corneal power of 10 eyes of 7 patients who had undergone rk with or without astigmatic keratotomy wit...

پایان نامه :دانشگاه تربیت معلم - تهران - دانشکده علوم 1393

in this thesis, structural, electronical, and optical properties of inverse pervskite(ca3pbo) in cubic phase have been investigated.the calculation have been done based on density functional theory and according to generalized gradiant approximate (gga) as correlating potential. in order to calculate the configurations, implementing in the wien2k code have been used from 2013 version. first of ...

Journal: :journal of lasers in medical sciences 0
aziza ahmed hassan ophthalmic department, national institute of laser enhanced science, cairo university, egypt. dina foad ghoneim ophthalmic department, national institute of laser enhanced science, cairo university, egypt. amr el-dib ophthalmic department, national institute of laser enhanced science, cairo university, egypt. salwa ahmed abdelkawi department of vision science, biophysics and laser science unit, research institute of ophthalmology, giza, egypt. ahmed medhat abdel-salam ophthalmic department, national institute of laser enhanced science, cairo university, egypt.

introduction: the aim of the present study was to evaluate the effect of photodynamic therapy in the treatment of experimental corneal neovascularization (nv) with benzoporphyrin derivative (bpd). methods: one group was considered as control (n=6 eyes) then, corneal nv was induced in 30 new zealand male rabbits (n=60 eyes) by placing 7.0 silk sutures at midstromal depth approximately1mm from th...

Journal: :Investigative ophthalmology & visual science 2002
Damien Gatinel Jacques Malet Thanh Hoang-Xuan Dimitri T Azar

PURPOSE To determine the ablation depths of customized myopic excimer laser photoablations performed to change corneal asphericity after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). METHODS A mathematical model of aspheric myopic corneal laser surgery was generated. The initial corneal surface was modeled as a conic section of apical radius R(1) and asphericity ...

2005

The use of a laser in place of a mechanical keratome for flap creation was a turning point in the field of refractive surgery. Visible and near infrared laser light are absorbed by the refractive structures of the eye and allowed to pass freely into the eye without effect at low-power densities. At high-power densities, the nonlinear optical properties of the cornea lead to absorption, generati...

Journal: :Physics in medicine and biology 2004
Young L Kim Joseph T Walsh Thomas K Goldstick Matthew R Glucksberg

We report the effect of changes in the corneal hydration on the refractive index of the cornea. Using optical coherence tomography (OCT), the geometrical thickness and the group refractive index of the bovine cornea were derived simultaneously as the corneal hydration was varied. The corneal hydration was then calculated from the corneal thickness. The group refractive index of the cornea incre...

2012
Sanja Masnec Olujić

In astigmatism variations in the curvature of the cornea or lens along different meridians prevent the light rays from focusing onto a single point. Corneal refraction depends on the corneal curvature. If the cornea is more curved, the power of refraction is higher and vice versa. Corneal and lenticular astigmatism can complement or cancel each other. Their summation represents the so called “t...

2012
Atsushi Nakazawa Christian Nitschke

Eye gaze tracking (EGT) is a common problem with many applications in various fields. While recent methods have achieved improvements in accuracy and usability, current techniques still share several limitations. A major issue is the need for external calibration between the gaze camera system and the scene, which commonly restricts to static planar surfaces and leads to parallax errors. To ove...

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