Biomedical subjects
Publications and source records attributed to Jack T Holladay.
This article is the sixth annual printing of the International Intraocular Lens & Implant Registry. A total of 1548 intraocular lenses (IOLs) and nonoptical implants from 33 manufacturers are availabe to surgeons in 2004.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
This is the fifth annual printing of the International Intraocular Lens and Implant Registry. A total of 1498 intraocular lenses (IOLs) and nonoptical implants from 33 manufacturers are available to surgeons in 2003.
Explore the source record for details and available documents.
This article is the fourth annual update of the International Intraocular Lens & Implant Registry. A total of 1348 intraocular lenses or nonoptical implants from 34 manufacturers are available to surgeons in 2002.
PURPOSE: To determine the relationship between the spherical refractive change after myopic excimer laser surgery and the effective optical zone (EOZ) and corneal asphericity determined by corneal topography. SETTING: Baylor College of Medicine, Houston, Texas, USA. METHODS: Preoperative and postoperative topographies along with refractions were evaluated in all patients who had had laser in situ keratomileusis since January 1999 and had at least 6 months of follow-up. The VISX Smoothscan S2 excimer laser and the Hansatome microkeratome (Bausch & Lomb) were used in all cases. Because optical zones are oval with astigmatic treatments with the VISX laser, only patients with spherical refractions and treatments were included. Thirty-nine cases met the criteria; their treatments ranged from -1.50 to -18.00 diopters (D). The preoperative and postoperative corneal asphericities (Q-values) were taken directly from the Holladay Diagnostic Summary Report on the EyeSys 2000, version 4.0. The mean diameter of the optical zone was measured on the local radius of curvature map using the outer edge of the yellow zone, which corresponds to 2 color changes or approximately 0.50 D steepening from the mean central radius (green). RESULTS: The EOZ decreased as the amount of treatment increased. The decrease was slightly nonlinear, decreasing slightly more rapidly at higher treatments. For an "intended" 6.0 mm optical zone, the nominal EOZs from the least-squares second-order polynomial regression were 6.0 mm for -1.5 D, 5.4 mm for -5.0 D, 4.6 mm for -10.0 D, 3.8 mm for -15.0 D, and 3.2 mm for -18.0 D. The least-squares second-order polynomial regression yielded a standard error of the estimate (SEE) of +/- 0.22 mm (R(2) = 0.90). The asphericity increased nonlinearly in a positive direction (oblate) with the amount of treatment, indicating greater amounts of correction produced progressively more oblate corneal surfaces. The least-squares second-order polynomial regression yielded an SEE of +/- 0.42 (R(2) = 0.55). CONCLUSIONS: The EOZ decreased and the Q-value increased with the amount of myopic excimer laser treatment. The optical zone was approximately 4.3 mm with a spherical treatment of -12.0 D. These findings may explain the clinical studies that indicate high myopic treatments (above -12.0 D) are associated with poor visual outcomes.
PURPOSE: The aim of this study was to design and evaluate in the laboratory a new intraocular lens (IOL) intended to provide superior ocular optical quality by reducing spherical aberration. METHODS: Corneal topography measurements were performed on 71 cataract patients using an Orbscan I. The measured corneal surface shapes were used to determine the wavefront aberration of each cornea. A model cornea was then designed to reproduce the measured average spherical aberration. This model cornea was used to design IOLs having a fixed amount of negative spherical aberration that partially compensates for the average positive spherical aberration of the cornea. Theoretical and physical eye models were used to assess the expected improvement in optical quality of an eye implanted with this lens. RESULTS: Measurements of optical quality provided evidence that if this modified prolate IOL was centered within 0.4 mm and tilted less than 7 degrees, it would exceed the optical performance of a conventional spherical IOL. This improvement occurred without an apparent loss in depth of focus. CONCLUSION: A new IOL with a prolate anterior surface, designed to partially compensate for the average spherical aberration of the cornea, is intended to improve the ocular optical quality of pseudophakic patients.
PURPOSE: To describe a novel excimer laser ablation algorithm, termed optimized prolate ablation (OPA), that uses both topography and ocular aberrometry and maintains or improves the natural corneal shape postoperatively. METHODS: A descriptive article outlining the theory behind this OPA algorithm. RESULTS: The theoretical changes to the ablation algorithm described in this article will produce a prolate cornea postoperatively. CONCLUSIONS: OPA treated eyes will have equal or better visual quality than preoperatively because age-related changes from lenticular spherical aberration are measured and treated.