Document Detail

An improved universal theoretical formula for intraocular lens power prediction.
MedLine Citation:
PMID:  8271166     Owner:  NLM     Status:  MEDLINE    
Although available empirically derived and theoretical formulas perform adequately for eyes of average axial length, both have been shown to be deficient for eyes that have unusually short and long axial lengths. I developed a formula based on a theoretical model eye in which anterior chamber depth is related to axial length and keratometry. A relationship between the A-constant and a "lens factor" is also used to determine anterior chamber depth. The location of the intraocular lens' principle planes of refraction is retained as a relevant variable in the formula, and the user need not know the material and construction of the lens and or its constant. I compared the new formula with the SRK II, Holladay, and SRK/T formulas in a group of 100 unselected patients and in selected subgroups of patients with average, short, and long axial lengths. The new formula was significantly more accurate than the other third-generation formulas and maintained its accuracy in the subgroups. The formula can be described as universal because it can be used for different lens styles and for eyes with short, medium, and long axial lengths.
G D Barrett
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Journal of cataract and refractive surgery     Volume:  19     ISSN:  0886-3350     ISO Abbreviation:  J Cataract Refract Surg     Publication Date:  1993 Nov 
Date Detail:
Created Date:  1994-02-01     Completed Date:  1994-02-01     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:  713-20     Citation Subset:  IM    
Lions Eye Institute, Perth, Western Australia.
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MeSH Terms
Anterior Chamber / anatomy & histology
Cataract Extraction
Eye / anatomy & histology
Lenses, Intraocular*
Models, Anatomic
Optics and Photonics*
Refraction, Ocular
Regression Analysis*
Retrospective Studies

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