Biomedical subjects
Publications and source records attributed to M Van der Karr.
Interlenticular opacification (ILO) developed 7 months after secondary acrylic piggyback lens implantation in which the anterior lens was placed in the bag. This resulted in glare and a hyperopic shift. Treating the ILO with the neodymium:YAG laser successfully reduced the glare and corrected the hyperopic shift.
OBJECTIVE: To determine the safety and efficacy of implanting a second intraocular lens (IOL) to correct pseudophakic refractive error. DESIGN: Noncomparative, prospective, consecutive case series. PARTICIPANTS: Eight eyes of eight normal pseudophakes and seven eyes of seven postpenetrating keratoplasty (PK) pseudophakes were included in the study. INTERVENTION: A second intraocular lens (IOL) was implanted anterior to the first in each eye in the study. MAIN OUTCOME MEASURES: Efficacy was determined based on the achieved refractive correction and Snellen uncorrected visual acuity measurements. Safety was determined based on loss of best-corrected visual acuity and operative and postoperative complications. RESULTS: Before surgery, spherical equivalents ranged from -5.12 diopters (D) to 7.5 D, with a mean absolute deviation from emmetropia of 3.38 D (1.62). After surgery, spherical equivalents ranged from -2.75 D to 0.5 D, with a mean absolute deviation from emmetropia of 1.21 D (0.90). Before surgery, only 7% of patients had 20/40 or better uncorrected vision, whereas after surgery, 50% had that level of vision. CONCLUSIONS: Implanting a second IOL is a viable option for correcting pseudophakic refractive error.
Preoperative and postoperative anterior chamber reactions in a series of cataract surgery patients were measured with a Kowa FC-1000 laser flare/cell meter by two different technicians, and clinical assessments of inflammation were recorded. The average cell and flare readings by the two technicians were nearly identical at every time point, showing the laser flare/cell measurements to be highly reproducible. The correlations between laser flare/cell measurements and clinical assessments at postoperative time points were highly positive (P < .01), demonstrating the validity of the laser flare/cell measurements.
Preoperative and postoperative anterior chamber reactions in a series of patients who had undergone cataract surgery were measured with a laser flare/cell meter (Kowa FC-1000, Kowa Instrument Corp, Japan) by two different technicians (A.M. and T.M.M.), and clinical assessments of inflammation were recorded. The average cell and flare readings of the two technicians were nearly identical at every time point, showing the laser flare/cell measurements to be highly reproducible. The correlations between laser flare/cell measurements and clinical assessments at postoperative time points were all highly positive (P less than .01), demonstrating the validity of the laser flare/cell measurements.
In a unilateral prospective clinical trial, 77 cases were randomized to receive a 3M multifocal IOL or a conventional monofocal implant. Multifocal cases had better uncorrected near vision than monofocal cases at the two to four month visit. Thirty percent of the multifocal cases had near acuity J1, while only 4% of the monofocal cases had that acuity. Eighty-seven percent of multifocal cases and 71% of monofocal cases had near acuities of J1 to J3. With distance correction in place, 54% of multifocal cases had near acuities of J1 to J2, while only 28% of monofocal cases had comparable acuities (P = .04). There have been no serious postoperative complications in either group.
A cadaver eye model was used to evaluate and quantify the use of thermokeratoplasty for steepening the central cornea to correct hyperopia. Four groups of eye-bank eyes were treated with four separate surgical plans. Each plan involved the placement of controlled thermal burns (in the depths of the corneal stroma, using a cautery probe) applied in a radial pattern up to a premarked optical zone. The plans differed in the sequence of surgical steps. All plans progressively added radials and applications (to decrease optical zone) in various sequences. Corneal curvature was measured at baseline and at each surgical step. As more surgery was done within each plan, the corneas became progressively steeper. Total mean changes in corneal curvature ranged from 16.26 diopters to 19.76 diopters, depending on the plan. At each optical zone, as the number of radials increased, the effect increased. With progressively smaller optical zone size, the effect also increased.
BACKGROUND: A systematic method of performing radial keratotomy enhancements in undercorrected eyes may increase accuracy and predictability and decrease the number of procedures required. A consecutive series of 372 radial keratotomy procedures, including 110 eyes that received enhancements under a systematic protocol, was evaluated. METHODS: Radial keratotomy was performed using the Reliable Keratotomy software, which uses the Thornton nomogram for primary radial keratotomy and provides a systematic method of performing enhancements. RESULTS: Ninety eyes (24%) received one enhancement, 16 eyes (4%) received two enhancements, and four eyes (1%) received three enhancements. Mean final spherical equivalent refraction was -0.44 D (-4.00 to +1.875 D, SD 0.86) for eyes that did not receive enhancements and -0.44 D (-2.50 to +1.00 D, SD 0.61) for eyes that had enhancements. Mean final residual myopia for the entire cohort was -0.44 D (-4.00 to +1.875 D, SD 0.79). At final examination, 242 (65%) eyes had a refraction within +/- 0.5 D and 298 (80%) within +/- 1.00. Among eyes that received enhancements, 75 (68%) had a refraction within +/- 0.50 D, and 89 (81%) within +/- 1.00 D; 40 eyes (36%) had uncorrected visual acuity of 20/20 or better, 99 eyes (90%) 20/40 or better, and all but one eye (99%) 20/80 or better at the final postoperative examination. Among the entire cohort, 130 eyes (35%) had uncorrected visual acuity of 20/20 or better, 312 (84%) had 20/40 or better, and 350 (94%) had 20/80 or better. No eye lost more than one line of spectacle-corrected visual acuity. CONCLUSION: A systematic approach to enhancement of undercorrected eyes after radial keratotomy, combined with accurate surgery, may reduce the need for multiple enhancements as well as the overcorrection rate, and provide improved uncorrected visual acuity.