Prospective interventional (QUASI experimental) comparative study~This study will be conducted on high myopic cataractous patients scheduled for phacoemulsification and IOL implantation in department of ophthalmology, Sohag university~patients will be divided into 2 groups one will be subjected to intraocular lens (IOL) calculation by optical biometry the second one will be subjected to intraocular lens (IOL) calculation by ultrasonic biometry~postoperative auto refraction after I month
the purpose of the study is to compare the accuracy of optical and ultrasonic biometry in intraocular lens (IOL) calculation in high myopic cataractous patients