Biomedical subjects

M G Raanan

Publications and source records attributed to M G Raanan.

22 records · Page 2Linked to original sources

PubMed1987

A consecutive series (1982-1985) of radial keratotomies performed with the diamond blade.

The refractive and visual results of a consecutive series of diamond knife radial keratotomy procedures were evaluated at one year after surgery as part of an ongoing prospective study of radial keratotomy. Of the 972 procedures performed, 656 eyes (67.5%) were examined one year or more after surgery. The average amount of preoperative myopia was 4.4 diopters with a range of 0.6 to 11.9 diopters; 638 (97%) of the eyes had a preoperative uncorrected visual acuity of 20/100 or worse. The mean change in spherical equivalent after one year was 4.5 diopters. One year after surgery, 496 (76%) of the eyes were within 1 diopter of emmetropia; 310 (47%) had uncorrected distance visual acuity of 20/20 or better, 579 (88%) were 20/40 or better, and all but one eye had uncorrected visual acuity improved by at least two Snellen lines. Evaluation of refractive and visual results at the final available examination of those eyes not examined one year after surgery showed that 256 (81%) of the eyes were within 1 diopter of emmetropia; 176 (56%) had uncorrected distance visual acuity of 20/20 or better, and 287 (91%) were 20/40 or better.

Adolescent↗

PubMed1986

A survey of intraocular lens explantations.

A survey of intraocular lens (IOL) explantations performed during the 1984 calendar year requested dates of implantation and explantation, lens manufacturer, and lens style for anterior chamber, posterior chamber, and iris-supported lenses. The survey was distributed to 3,640 members of the American Society of Cataract and Refractive Surgery and was published in the September 15, 1985, issue of Ocular Surgery News. Information on 1,087 IOL explantations performed during 1984 by approximately 530 surgeons was received. Extrapolation of our survey's responses to the universe of ophthalmic surgeons suggests that the number of IOL explantations ranges from 7,000 to 11,000 each year. The actual numbers and percentages of explantations as well as reported complications vary with the relative percentage of any given manufacturer's lenses implanted and with the popularity of lens styles during the preceding years of implantation. For these reasons, the individual performance of various lenses should be read in the context of this report, considering the time of implantation and the practices that were then in vogue. This survey provides a general picture of IOL explantation but, more importantly, it provides a better structure for a report on 1985 explantations, which will follow.

Corneal Diseases↗

PubMed1986

Progressive hyperopia in radial keratotomy. Long-term follow-up of diamond-knife and metal-blade series.

In an earlier report, the authors demonstrated a trend toward progressive hyperopia in radial keratotomy (RK) patients examined between one and three to four years postoperatively. In those 109 cases, the surgeries were performed using a metal-blade instrument. In the following study, the metal-blade series was updated to a total of 225 procedures, and a more recent series of 300 procedures performed on 228 patients was examined in which a diamond-knife cutting instrument was used. Patients had uncorrected visual acuity determination, cycloplegic refractions with best corrected visual acuity measurements and keratometry measurements. The authors demonstrated a hyperopic shift in the distribution of postoperative spherical equivalent (SE) values across time such that higher proportions of cases in both metal-blade and diamond-knife series were at least 1.0 diopter (D) away from emmetropia at 24 and 48 months than was the case at 12 months after surgery. Regression analysis determined that none of the preoperative or surgical variables known to affect refractive outcome of RK (alone or in combination) could account for the changes in refraction seen during the course of postoperative time. In general, changes in keratometry paralleled refractive changes, but were somewhat smaller in magnitude.

Cornea↗

PubMedDate not supplied

Efficacy and safety of excimer laser photorefractive keratectomy and radial keratotomy for bilateral myopia.

PURPOSE: To compare the safety and efficacy of radial keratotomy (RK) and photorefractive keratectomy (PRK) to correct myopia. METHODS: In this randomized, prospective, parallel-group study, 33 patients with bilateral myopia of 1.00 to 5.00 diopters (D) had PRK in one eye and RK in the other. The order of surgeries and treatment assignments were randomized, and the bilateral surgeries were within 1 week for each patient. Data were collected using standardized procedures. Clinical measurements and satisfaction surveys were taken in masked fashion. RESULTS: Eyes that had PRK had statistically significantly more residual myopia than RK-treated eyes at 3, 6, and 12 months postoperatively. This result was attributed to the use of an older excimer laser PRK algorithm that was used at the initiation of the study. No eye that had PRK was overcorrected by 0.50 D or more at 1 year postoperatively, while seven eyes that had RK were overcorrected by at least 0.50 D and six were overcorrected by 1.00 D. Eyes that had PRK had a statistically significant mean shift in the myopic direction between 6 and 12 months postoperatively; two RK eyes had hyperopic shifts of 1.00 D. Three RK eyes and two PRK eyes failed to achieve an uncorrected visual acuity of 20/40 or better by 12 months postoperatively. No eye lost any best corrected visual acuity. CONCLUSION: The two procedures were comparably safe and effective in treating mild to moderate myopia under this protocol. Eyes that had PRK were somewhat more myopic at 1 year after surgery, attributable to the older PRK ablation algorithm. Adoption of newer (current) laser algorithms has improved the predictability of PRK. There was also evidence of reduced variability of outcome in the PRK group. The PRK eyes did not exhibit hyperopic shifts during the 1 year follow-up.

Adolescent↗