ABSTRACT
Background Toric intraocular lens (Toric IOL) is a well accepted method of correct of corneal astigmatism.Axial misalignment,including the error of intraocular lens alignment during surgery and rotation of Toric IOL,is the main barrier to the precise alignment of Toric intraocular lenses.Therefore,the angle of axial misalignment is a main index to evaluate the effectiveness of Toric IOL implantation.Objective The present study is to describe a method of precisely detecting Toric IOL misalignment using postoperative digital photograph.Methods A measuring template (polar coordinates) was constructed using Adobe Photoshop software.Minimum graduate to detect the Toric axis was 1° (maximum error 0.5°).The clinical data of 24 eyes undergone Toric IOL implantation was retrospectively analyzed.Corneal astigmatism was detected by rotating Scheimpflug camera (Pentacam) or slit scan (Orbscan).Digital retro illumination picture was photographed after mydriasis.The picture was analyzed by our derived template.The steepest corneal axis and the axis of Toric IOL were then determined.The misalignment of Toric IOL was determined as the angle between the steepest corneal axis and the axis of Toric IOL.Misalignment of Toric IOL and its distribution were analyzed by statistical means.Results A method using polar coordinates and digital photo to precisely detect Toric IOL misalignment was derived.Mean Toric IOL misalignment was 10.93±6.90 degrees (0-24 degrees) in the 24 cases.The axial misalignment in all of cases were within 25 degrees,including clockwise in 14 eyes(58.33%),anticlockwise in 10 eyes (41.67%).In this study,the misalignment angle of 4 eyes were within 5 degrees;11 eyes were 5 to 10 degrees;1 eye was 10 to 15 degrees;6 eyes were 15 to 20 degrees;2 eyes were 20 to 25 degrees.Conclusion The method is feasible to the direction of Toric IOL misalignment in clinic.