Ophthalmic Assistant

Answer: B - inaccurate.

If a patient has had any type of surgery where the surface of the cornea has been altered, the direct keratometry reading will be inaccurate. Since the readings are based on the index of refraction of the cornea and surgery has changed this, using the direct reading willlead to incorrect calculations for intraocular lens choice, for instance. A formula must be used toarrive at a more accurate estimation of the corneal power.