PubMed · 9850884
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D D Koch. 1998. Reporting astigmatism data.. https://doi.org/10.1016/s0886-3350(98)80335-0
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OBJECTIVE: To determine the incidence and severity of complications from laser in situ keratomileusis (LASIK) for the correction of myopia by experienced and inexperienced surgeons. DESIGN: Prospective, observational clinical study. PARTICIPANTS: Fourteen surgeons and 1062 eyes of 574 myopic patients who desired surgical correction of myopia ranging from -2.00 to -22.50 diopters (D; mean, -7.57 D) and astigmatism no greater than 4.00 D participated in this study. INTERVENTION: Myopia was corrected with LASIK. Astigmatism was corrected with arcuate keratotomy at the same time as the initial procedure or subsequently. MAIN OUTCOME MEASURES: Primary outcome measures were change in best spectacle-corrected visual acuity (BSCVA) and the incidence of complications. RESULTS: Eyes were followed for a mean of 9.5 months after their last surgical procedure (range, 2 weeks-21 months). Three hundred eighty-one eyes (36%) underwent 468 enhancement procedures 3 months or more after the initial treatment. There were 27 (2.1%) intraoperative and 40 (3.1%) postoperative complications. Laser ablation was not performed during the initial treatment of 17 (1.6%) eyes because of intraoperative complications. Seventy-four eyes gained 2 or more lines of BSCVA, while 50 eyes lost 2 or more lines of BSCVA. Only three eyes lost two or more lines of BSCVA to a level worse than 20/40. One eye with a flap buttonhole (BSCVA 20/50) also had an epiretinal membrane. The second eye (BSCVA 20/60) had a flap buttonhole that may have been related to a previous corneal transplant. The third eye (-22.50 D before surgery) had a rhegmatogenous retinal detachment develop, reducing BSCVA from 20/60 to 20/200. The incidence of intraoperative complications decreased from 3.1% during the first 3 months to 0.7% during the last 9 months of the study (P = 0.02). CONCLUSIONS: LASIK is acceptably safe for the correction of myopia. Although complications occur in approximately 5% of cases, these rarely lead to visual loss of more than two Snellen lines and postoperative acuity below 20/40. Flap buttonholes were more likely to cause loss of BSCVA than free or incomplete flaps (P = 0.02); flap buttonholes may be more likely in eyes that have undergone previous surgery. Complication rates can be reduced as the surgical team gains experience.
PURPOSE: To evaluate a computer program to modulate the visual impairment caused by intraocular lens (IOL) misalignment and visualize results obtained by numerical calculations. SETTING: Department of Ophthalmology, Medical Faculty of Charles University, Prague, Czech Republic. METHODS: The optic imagery of a Landolt circle was calculated using a ray-tracing computer program. Visual aberrations resulting from a decentered and/or tilted IOL were studied using this program and compared with theoretical calculations. RESULTS: The IOL decentration and/or tilt shifted the postoperative refractive errors toward myopia and astigmatism (oblique). The combination of IOL decentration and tilt produced a refractive error that depended on the relationship between the geometrical axes of the decentration and tilt. The refractive error can be enhanced or diminished depending on the relationship of these axes. CONCLUSIONS: These findings verify the results calculated by paraxial vergence equations. A ray-tracing program simulated the optic imagery for various kinds of IOL misalignment and IOL optic properties.
PURPOSE: To assess whether a unilateral asymmetric radial enlargement of a corneal tunnel incision for implantation of foldable intraocular lenses yields advantages over conventional linear enlargements. SETTING: Department of Ophthalmology, University of Brussels, VUB, Belgium. METHODS: Asymmetric corneal tunnel incisions with an L-shaped entrance and a concave exit were compared with equivalent conventional linear incisions in patients and in postmortem eyes. RESULTS: The asymmetric no-stitch L-designs scored consistently better than the symmetric linear designs in induced astigmatism, postoperative astigmatic shift, complications, and pressure resistance. CONCLUSION: An asymmetric corneal L-incision is superior to a conventional symmetric linear incision.