An ophthalmic apparatus for measuring spatial distances within a patient's eye is disclosed. The apparatus can be used to measure, for example, the capsular bag depth in an aphakic eye. The spatial measurement system can direct laser light into a patient's eye so that a portion of the light is scattered by the capsular bag. The scattered light can be directed to a detector where spots can be formed corresponding to the locations on the capsular bag from which the light was scattered. The distance from the cornea to the capsular bag can be determined based, for example, at least in part on the distance between the spots formed on the detector. In some embodiments, the apparatus can include a surgical microscope and/or a wavefront aberrometer. In some embodiments, an alignment system can be used to precisely position the apparatus relative to the patient's eye. The ophthalmic apparatus can be used for variety of ophthalmic procedures, such as predicting the postoperative position of an intraocular lens (IOL) and determining appropriate optical power for the IOL.