RESUMEN
To determine corneal power for intraocular lens [IOL] power calculation in eyes with previous keratorefractive surgery. 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 7 cases. SRK-T formula with applanation method was used. Final refractions [SE] are presented. Patients included 7 male and 2 female subjects aged 51.2 +/- 9.3 [range 41-70 years]. Postoperative refraction was hyperopic [+1.5 D] in eyes with the CHM, variable and unpredictable in cases with the MKR and SimK and more desirable [-0.35 +/- 0.39 D] in cases of flattest K. In this latter group the best postoperative refraction was achieved in cases which 0.5 to 1.00 D was added to the calculated IOL power. It seems using topographically derived flattest K for IOL power calculation and adding 1.00 D to the calculated IOL power in eyes with previous myopic-refractive surgery, and using the steepest K together with subtracting 1.00 D from the calculated IOL power in eyes with previous hyperopic-refractive surgery is useful when pre-refractive surgery data are not available
RESUMEN
With the increasing number of keratorefractive surgical procedures in the past years, an increasing number of cataract operations in eyes with previous keratorefractive surgery is anticipated. Although cataract extraction seems to be feasible without major technical obstacles, intraocular lens [IOL] power calculation remains problematic. Insertion of measured k-readings after myopic photorefractive keratectomy [PRK], or laser in situ keratomileusis [LASIK] into standard IOL power-predictive formulas commonly results in substantial under correction and postoperative hyperopic refraction or anisometropia. Several methods have been developed to provide accurate measurements of corneal power which include: clinical history method, contact lens method, Feiz-Mannis formula, aphakic refraction technique, cornea bypass method and the BESSt formula. Newer methods such as the BESSt formula represent a significant step toward greater accuracy in IOL power calculation in eyes with previous laser refractive surgery, especially when prerefractive surgery data is unavailable. The "clinical history method" should be applied whenever refraction and k-reading before the keratorefractive procedure are available, however if the pre- refractive surgery data is unknown, the use of the flattest K value in the central 3 mm region of the topography map will be useful. This article briefly reviews each of the above-mentioned methods
RESUMEN
To report the clinico-pathologic features of an opacified single-piece hydrophilic acrylic intraocular lens [IOL]. A 48-year-old male patient was evaluated for glare and markedly decreased vision in his left eye four years after phacoemulsification and implantation of a single-piece hydrophilic acrylic IOL [Ophthalmed]. Best-corrected visual acuity was 20/60 and there was diffuse milky white opalescence of the IOL on slitlamp biomicroscopy. IOL explantation and exchange was performed and the explanted IOL was evaluated at the Eye Bank pathology laboratory by light microscopy. Full-thickness sections of the optic were stained with Hematoxylin and Eosin [H and E], Von Kossa and Gram Twort's staining methods. Gross examination of the IOL disclosed opacification of the optic and haptics. Microscopic analysis of the sections revealed diffuse fine basophilic granular deposits of variable size within the lens optic parallel to the lens curvature with a clear zone from the optic surface. The deposits were of high calcium content based on the dark brown appearance on Von Kossa staining. This is the first clinico-pathological report of IOL calcification with involvement of optic and haptics in Iran. IOL exchange is an effective treatment in cases with calcified hydrogel IOLs