Articles: PDF OnlyClinical evaluation of the Bio-Pen for axial length measurementShammas, John H. M.D.a, b, *; Swearingen, Michael O.D.bAuthor Information aDepartment of Ophthalmology, University of Southern California, Los Angeles bMilkie-Shammas Medical Eye Center, Lynwood, California. *Reprint requests to H. John Shammas, M.D., 3510 Century Boulevard, Lynwood, California 90262. The authors have no proprietary or financial interest in thr Bio-Pen instrument. Journal of Cataract & Refractive Surgery: January 1990 - Volume 16 - Issue 1 - p 120-122 doi: 10.1016/S0886-3350(13)80886-3 Free Metrics Abstract The axial length of 207 eyes was evaluated in a clinical comparison between the Bio-Pen biometric ruler and the Kretz 7200 MA A-scan unit. The overall correlation was 0.99. The Bio-Pen measurement averaged 0.056 mm shorter than the Kretz. The difference was statistically significant (P < .0001). The Bio-Pen was found to be a convenient and clinically accurate biometer. © Williams & Wilkins 1990. All Rights Reserved.