Automated keratometry in routine cataract surgery: Comparison of Scheimpflug and conventional values

• Published in: Journal of cataract and refractive surgery Vol. 37; no. 2; pp. 295 - 301
• Main Authors: Symes, Richard J., BSc, MRCOphth, Ursell, Paul G., MD, FRCOphth
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-02-2011; Elsevier
• Subjects: Adult; Aged; Aged, 80 and over; Automation; Biological and medical sciences; Cataract Extraction; Cohort Studies; Cornea - pathology; Diagnostic Techniques, Ophthalmological - standards; Humans; Lens diseases; Medical sciences; Middle Aged; Ophthalmology; Photography - methods; Photography - standards; Preoperative Care - standards; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgery of the eye and orbit; Eye disease; Cataract; Lens disease; Treatment; Surgery; Value; Ophthalmology; Anterior segment disease; Comparative study; Keratometry
• ISSN: 0886-3350; 1873-4502
• DOI: 10.1016/j.jcrs.2010.08.050

Purpose To compare the mean keratometry (K) readings obtained with a conventional automated keratometer (IOLMaster) and a Scheimpflug keratometer (Pentacam) in eyes having preoperative assessment for routine cataract surgery. Setting Epsom and St. Helier University Hospitals, London, United Kingdom. Design Evaluation of diagnostic technology. Methods Mean K values were obtained with the conventional and Scheimpflug keratometers. The following Scheimpflug readings were evaluated: anterior K, true net power, and Holladay equivalent K measured at 1.0 to 7.0 mm corneal diameters. Mean readings for each type of keratometry were compared. Bland-Altman plots were used to determine the 95% limits of agreement (LoA) for the conventional and Scheimpflug keratometers. Results The mean conventional K was statistically significantly greater than the mean Scheimpflug K for true net power and equivalent K at 1.0 mm, 2.0 mm, 3.0 mm, and 4.0 mm corneal diameters. The mean conventional K was significantly less than the equivalent K at 5.0 mm, 6.0 mm, and 7.0 mm. The smallest mean difference was for equivalent K at 4.5 mm (0.02 diopters [D]). The smallest 95% LoA were −0.68 to 1.16 D (equivalent K at 5.0 mm) and −0.91 to 0.95 D (equivalent K at 4.5 mm). Conclusions Overall, the equivalent K at 4.5 mm had the closest match with the conventional K values. The degree of interdevice variability with the conventional keratometer was lowest for the equivalent K at 4.5 mm and 5.0 mm, although this variability would be sufficient to influence intraocular lens power selection. Financial Disclosure Neither author has a financial or proprietary interest in any material or method mentioned.