[Hypotonia bulbi and gonadotropins in myotonic dystrophy]

Patients with myotonic dystrophy show ocular hypotony associated with primary hypogonadism and a secondary increase in the gonadotropins FSH and LH. By examining ten patients (nine men, one woman) with myotonic dystrophy and determining serum FSH and LH concentrations by radioimmunoassay, the authors tried to evaluate whether the decrease in intraocular pressure (IOP) seen in myotonic dystrophy might be related to increase levels of gonadotropins. The IOP of the patients with myotonic dystrophy (mean 10.6 mm Hg, SD 3.9 mm Hg) was significantly lower (P less than 0.0005) than that of a randomly selected control group. In all nine male patients serum FSH concentrations (mean 41.7 mIU/ml, SD 18.9 mIU/ml, normal range 0.9-9.8 mIU/ml) and serum LH concentrations (mean 18.6 mIU/ml. SD 6.8 mIU/ml, normal range 2.2-12.0 mIU/ml) were significantly higher (FSH: P less than 0.0005, LH: P less than 0.05) than those of a control group of four normal men. The female patient's FSH was elevated (11.5 mIU/ml, normal range 1.7-8.5 mIU/ml), her LH concentration was slightly elevated (15.5 mIU/ml, normal range 2.5-15.4 mIU/ml). A statistically significant correlation was found between elevated LH concentrations and decreased IOP (P less than 0.05) but no such correlation between FSH and IOP (P less than = 0.17). Endogenous circulating gonadotropins may play an important role in regulating aqueous inflow via cyclic AMP which is produced by ciliary epithelia and causes a decrease in the rate of aqueous humor production. This theory is corroborated by humor production. This theory is corroborated by the authors' data and by experimental studies by Sears and co-workers.