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A-Scan Ultrasound: Biometry

A-Scan Ultrasound: Biometry Biometry is used to determine axial length of the eye and to determine the depth of the anterior chamber, lens and vitreous cavity.  The A-scan ultrasound is the most commonly employed, since it is an essential part of the preoperative evaluation of cataract surgery patients.  It is used to determine the appropriate dioptric power of the intraocular lens (IOL) implanted at the time of cataract extraction surgery.  This allows the correct selection of an intraocular lens (IOL) implant through a series of calculations.  The A-scan technique takes multiple, accurate readings on both eyes.