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Biomedical subjects

Y Kora

Publications and source records attributed to Y Kora.

8 recordsLinked to original sources

Long-term study of children with implanted intraocular lenses.

We studied children between five and 15 years of age who were implanted with intraocular lenses (IOLs). The subjects comprised eight cases of traumatic cataract, 11 of congenital cataract, and six of steroid cataract. The follow-up ranged from four months to nine and one half years. Twenty of the eyes studied achieved a postoperative visual acuity of equal to or better than 20/40. Binocular function was retained in most cases. Postoperative complications included seven cases of posterior iris synechia, three of iris capture, one of transitory elevated intraocular pressure, and one of cystoid macular edema. Corneal endothelial studies were normal in the eyes in which posterior chamber IOLs were implanted.

Adolescent

Modified SRK formula for axial myopia (24.5 mm < or = axial length < 27.0 mm).

When used for eyes with greater than average axial length (AXL), the SRK formula has been reported to have a tendency to yield more myopic refractions than those predicted. To further evaluate such findings, we studied 609 eyes with AXLs between 24.5 and 27.0 mm. Comparing the predicted with the actual refractions and calculating the range of errors, we found that the postoperative refractions were more myopic than predicted. Then, based on our evaluation of the relationship between the postoperative refractions and the powers of the implanted intraocular lenses (IOLs), we devised the following formula: R = 0.8 x (P - I) + 0.57 (P < .01) in which R = the postoperative refraction; P = the emmetropic IOL power; and I = the actual IOL power. Testing this modified SRK formula in 55 additional eyes, we found that the predicted postoperative refractions it yielded were more accurate than those calculated using five earlier formulas.

Cataract Extraction

A new endoscope for ophthalmic microsurgery.

We present an endoscope designed for ophthalmic microsurgery. The handpiece contains a charge-coupled device, a solid-state imager (250,000 pixels), and a probe (either 0.89 or 1.5 mm in diameter), including the light guide. The light source is a halogen lamp. The clear views the instrument provides of the ciliary sulcus and ciliary body behind the iris make it useful in secondary posterior chamber intraocular lens implantation using the ciliary sulcus suturing technique, and in endolaser photocoagulation of the ciliary body in end-stage glaucoma. It also is useful in performing vitrectomy in cases in which visualization is difficult because of corneal opacification or fluid-gas exchange.

Cataract Extraction

Sulcus fixation of posterior chamber lenses by transscleral sutures.

Sulcus fixation of posterior chamber lenses by transscleral sutures was performed in 23 cases. We used new techniques to be sure that the sulcus was pierced accurately and the suture was placed in the posterior chamber instead of the ruptured capsule. This paper describes these techniques and the clinical results of 23 cases.

Aged

Errors in IOL power calculations for axial high myopia.

We studied 115 eyes with axial lengths of 27 mm or more after implantation of a posterior chamber intraocular lens in order to determine discrepancies between the predicted refractions and the actual postoperative refractions. We then reviewed the three major variables used to predict refractions in these eyes--corneal curvature, anterior chamber depth, and axial length measurements--in an attempt to determine whether any of these variables were correlated with the discrepancies. We found that the main reason for postoperative refractive error was inaccurate measurements of preoperative axial length.

Eye

A simple modified SRK formula for severely myopic eyes.

We describe our modification of the most accurate intraocular lens power calculation formula currently used, the SRK formula, to improve the accuracy with which it can be used to calculate the power of IOLs that are implanted in severely myopic eyes, especially in those with exceptional axial length. This modified formula, which we call the L-SRK, is I = A - 2.5 L - 0.9 K - 1.69R - 1.69 (where I = the actual implanted IOL power; A = the A-constant; L = the axial length; K = the average keratometer reading; and R = the predicted postoperative refraction). The results achieved using this modified formula demonstrate its superior accuracy in calculating lens powers for severely myopic eyes.

Humans