Myotonic dystrophy is primarily a disease of the voluntary muscular system, the first manifestation of which usually occurs as a progressive distal weakness in the second or third decade.1 The myotonic phenomenon consists of a sustained muscle contraction with slow relaxation, most frequently observed on mechanical testing of the thenar eminence or tongue, or reflexly on hand shaking or forcible eye closure. Amyotrophy of the facial and sternomastoid muscles is often an early sign, and ptosis may be a prominent feature, though extraocular muscle palsies are less common and diplopia is rare.
Also commonly noted in this dominant heredofamilial degeneration2 are frontal baldness, atrophy of the testicles or ovaries, premature senility, mental enfeeblement,3 hypometabolism,1 hyperostosis interna,4 cardiac abnormalities,5 and atrophy of the pituitary and adrenal glands.6
The punctate multicolored subcapsular lens opacities were characterized as part of the disease by Greenfield.7 Other
SIMON KA. Diabetes and Lens Changes in Myotonic Dystrophy. Arch Ophthalmol. 1962;67(3):312-315. doi:10.1001/archopht.1962.00960020314007