Patent ID: 8733932

Claim:
A method for measuring an ocular axial length of an examinee's eye with an ophthalmic ultrasonic diagnosing apparatus, the apparatus comprising: an ultrasonic probe for A-mode measurement comprising a transducer that is arranged to emit an ultrasonic wave toward the inside of the eye, and receive return echoes from constituent parts inside the eye; and an analysis unit that is arranged to identify, by analyzing signals of the received return echoes, the respective return echo signals as a return echo signal from a cornea of the eye, a return echo signal from an intraocular lens that is implanted in the eye, multiple return echo signals that are produced from the return echo signals that repeatedly return between the intraocular lens and the transducer, and a return echo signal from a retina of the eye, while distinguishing the retinal return echo signal from the multiple return echo signals based on at least one of a property shown by the multiple return echo signals and a property shown by the retinal return echo signal, and calculate the ocular axial length based on the corneal return echo signal and the retinal return echo signal, the method comprising: identifying, via the analysis unit, the retinal return echo signal by at least one of: a first method for distinguishing, based on periodicity of the return echo signals that appear subsequent to the intraocular lens return echo signal and at a retinal side, the retinal return echo signal from the multiple return echo signals; a second method for distinguishing, based on a property shown by the retinal return echo signal that is obtained by making a search of the return echo signals sequentially from the retinal side to an intraocular-lens side, the retinal return echo signal from the multiple return echo signals; and a third method for distinguishing, based on a difference in attenuation between the retinal return echo signal and the multiple return echo signals, the difference being made when gains of the signals are adjusted, the retinal return echo signal from the multiple return echo signals, wherein the multiple return echo signals appear subsequent to the return echo signal from the intraocular lens and prior to a boundary position between the retina and a vitreous body, and wherein the retinal return echo signal appears subsequent to the boundary position.