| Topographic changes in corneal asphericity and effective optical zone after laser in situ keratomileusis. | |
| | |
MedLine Citation:
|
PMID: 12036634 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
|
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. |
| | |
Authors:
|
Jack T Holladay; Joseph A Janes |
Related Documents
:
|
15313284 - Clinical course of severe central epithelial defects in laser in situ keratomileusis. 23038944 - Oral hygiene education in adolescence based on the precaution adoption process model. 17965754 - Modified cataract surgery with telescopic magnification for patients with age-related m... 18251434 - De novo cataract development following a standard course of hyperbaric oxygen therapy. 19150214 - Does discharge disposition after primary total joint arthroplasty affect readmission ra... 20735904 - Association between erectile function and lower urinary tract symptoms in patients trea... |
Publication Detail:
|
Type: Comment; Journal Article |
Journal Detail:
|
Title: Journal of cataract and refractive surgery Volume: 28 ISSN: 0886-3350 ISO Abbreviation: J Cataract Refract Surg Publication Date: 2002 Jun |
Date Detail:
|
Created Date: 2002-05-30 Completed Date: 2002-07-29 Revised Date: 2004-11-17 |
Medline Journal Info:
|
Nlm Unique ID: 8604171 Medline TA: J Cataract Refract Surg Country: United States |
Other Details:
|
Languages: eng Pagination: 942-7 Citation Subset: IM |
Affiliation:
|
Baylor College of Medicine, Houston, Texas, USA. holladay@docholladay.com |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
Cornea
/
pathology*,
physiopathology* Corneal Topography* Humans Keratomileusis, Laser In Situ* Myopia / physiopathology, surgery* Postoperative Care Preoperative Care Refraction, Ocular |
| Comments/Corrections | |
Comment On:
|
J Cataract Refract Surg. 2002 Jun;28(6):948-53
[PMID:
12036635
]
|
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: Photorefractive keratectomy in children.
Next Document: Evaluation of corneal functional optical zone after laser in situ keratomileusis.