purpose: in the present study we have tried to find the most reliable intraocular lens (iol) power calculation formula in patients with keratoconus (kcn) and cataract. methods: in a prospective case series between october 2010 and march 2012, eligible patients with cataract and kcn underwent phacoemulsification with iol implantation. preoperatively, based on iol master keratometric data iol pow...

purpose: to describe the biometric changes and their effect on intraocular lens (iol) power calculation after trabeculectomy and to compare the accuracy of four formulas namely srk/ii, srk/t, holladay and hoffer q for iol power calculation in these patients. methods: thirty-four eyes of 31 glaucoma patients who were scheduled for primary trabeculectomy were enrolled. a non-contact biometry devi...

The matrix calculation was applied to Gaussian optics. Matrices were defined for a single diopter, a lens, an association of two centered systems having the same axis when the origins are taken at the vertices of the first and last refracting surfaces. The matrix formula then was used to calculate the power of the emmetropizing lens implant, and its results compared with the ones obtained by fi...

purpose: to evaluate ocular biometric changes after phacotrabeculectomy and its effect on intraocular lens power calculation. methods: twenty six eligible eyes (24 patients) underwent phacotrabeculectomy. they were reexamined at least 6 months after the operation in a historical cohort study. main outcome measures included axial length (al) with contact a- scan (us-8000, nidek, gamaguri, japan)...

The theoretical basis for the calculation of corneal refractive power from anterior curvature is considered. It is shown that the power can be calculated with sufficient accuracy from one simple formula provided the refractive index of the 'cornea' is 1.3315. It is suggested that keratometer readings should be calibrated with this value in order to increase the accuracy in intraocular lens calc...

purpose: to determine corneal power for intraocular lens (iol) power calculation in eyes with previous keratorefractive surgery. methods: in 13 eyes of 9 patients with previous keratorefractive surgery undergoing phacoemulcification, iol power was calculated using the clinical history method (chm) in one case, manual keratometry (mkr) in 2, simk in 3, and flattest k (topographically derived) in...