We describe a 36-year-old female who suffered from presenile cataract (nuclear sclerosis and posterior subcapsular opacity, with more-severe disease in the right eye than in the left) and report the use of some ophthalmologic examinations to evaluate the anatomic structures and visual functions of both eyes. Slit-lamp biomicroscopy showed increasing horizontal and vertical corneal diameters (14.0/13.5 mm) and iridodonesis. The pupils could not be fully dilated, and the lenses exhibited cataractous changes. The postlimbal depths were 1.772 mm (OD) and 1.690 mm (OS) (normal value, < 0.20 mm). The results of gonioscopy, specular microscopy, Goldmann visual field, and intraocular pressure evaluation were all within normal limits. Because the patient had bilateral megalocornea in the absence of glaucoma, a very deep anterior chamber depth, secondary effects of iridodonesis, and changes to cataractous lenses, anterior megalophthalmos was diagnosed. This disease is rare. Secondary effects such as iridodonesis, miosis, atrophy of the iris stroma lens subluxation, and occurrence of cataractous lens should be kept in mind.