Document Detail

Natural history of central topographic islands following excimer laser photorefractive keratectomy.
MedLine Citation:
PMID:  8972365     Owner:  NLM     Status:  MEDLINE    
PURPOSE: To assess the incidence and natural history of central corneal topographic islands following excimer laser photorefractive keratectomy (PRK) and photoastigmatic refractive keratectomy (PARK). SETTING: A dedicated corneal diseases and refractive surgery unit within a National Health Service Trust ophthalmology unit in the United Kingdom. METHODS: Corneal topographic analysis was performed in a prospective study of 100 eyes of 75 consecutive patients who had PRK. All PRK/PARK excimer laser photorefractive procedures were performed by two surgeons observing a standardized protocol using a VISX 20/20 excimer laser. Mean preoperative myopic error was 5.54 diopters (D) +/- 3.44 (SD). Corneal topographic analysis was performed on all eyes preoperatively, 1 week postoperatively, and monthly thereafter for a minimum of 6 months or until central islands, if present, resolved. All patients had a minimum 12 months follow-up. RESULTS: Postoperatively, 29 eyes (29%) demonstrated central corneal topographic islands of greater than 3.00 D topographic power by computerized videokeratography (CVK). All central islands were identified in the first 4 weeks postoperatively. In all cases the differential dioptric power, created by the central islands within the ablation zone, decreased rapidly; within 6 months, 26 (90%) central islands had fully resolved without further treatment, and the remaining 3 (10%) resolved within 1 year of photorefractive surgery. The occurrence of central islands was related to higher preoperative myopic spherical equivalent (P = .01), greater attempted laser correction (P = .01), and greater projected depth of ablation (P = .01) (Student's two-tailed t-test). CONCLUSIONS: Central corneal topographic islands occurred in a significantly higher proportion of eyes having excimer laser photorefractive surgery than previously believed. The islands were associated with decreased unaided vision, reduced best spectacle-corrected acuity, and other troublesome visual symptoms; however, the central islands, along with their associated visual effects, usually resolved without surgical intervention within 6 months postoperatively.
C N McGhee; I G Bryce
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of cataract and refractive surgery     Volume:  22     ISSN:  0886-3350     ISO Abbreviation:  J Cataract Refract Surg     Publication Date:  1996 Nov 
Date Detail:
Created Date:  1997-02-26     Completed Date:  1997-02-26     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8604171     Medline TA:  J Cataract Refract Surg     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1151-8     Citation Subset:  IM    
Corneal Diseases and Excimer Laser Unit, Sunderland Eye Infirmary, United Kingdom.
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MeSH Terms
Astigmatism / surgery*
Cornea / pathology*,  surgery
Corneal Diseases / etiology*,  pathology
Image Processing, Computer-Assisted
Lasers, Excimer
Middle Aged
Myopia / surgery*
Photorefractive Keratectomy / adverse effects*
Postoperative Complications / etiology,  pathology
Prospective Studies
Comment In:
J Cataract Refract Surg. 1999 Mar;25(3):302-4   [PMID:  10079427 ]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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