Keratometry and post-operative astigmatism

Abstract

SUMMARYTotal post-operative refractive astigmatism and kerato metric corneal astigmatism were determined in patients following cataract surgery. By comparing the results of the two methods, the value of keratometry as a simple and quick procedure for identification of surgically induced astigmatic errors was established. It is proposed that this method should be used before final refraction in an attempt to increase clinic efficiency and reduce further appointments resulting from surgically induced astigmatism.A frequent complications of cataract extraction is sur gically induced astigmatism I. This is predominantly cor neal although other factors may contribute such as intraocular lens decentration and tilt.2 In the majority of cases the astigmatism is amenable to correction by selec tive suture removal. 3 In many units it is routine for post-operative cataract patients to be sent to non-hospital based optometrists for refraction. If patients are not refracted in clinic, detection of high astigmatism requires further out-patient appoint ments thereby reducing clinic efficiency.The purpose of this study was to determine the value of keratometry as a screening method for high degrees of astigmatism following cataract surgery. The total astig matism determined by refraction was compared with cor neal astigmatism determined by keratometry.As a result of the relationship between irregular suture tension and corneal astigmatism, this study further assesses the role of keratome try in identification of tight sutures requiring removal. PATIENTS AND METHODSA randomly selected sample of 77 eyes of 69 patients was taken at six to eight weeks following extracapsular catar act surgery and posterior chamber intraocular lens implan tation. Cataract surgery was performed by the consultants and resident staff at the Birmingham and Midland Eye Hospital and Selly Oak Hospital, Birmingham. Of the