Tetany cataract, also known as hypocalcemic cataract, is caused by abnormally low serum calcium levels. Patients with hypocalcemia often exhibit tetany in the extremities, leading to its name.
Etiology
The condition is commonly associated with congenital hypoparathyroidism, accidental damage to the parathyroid glands during thyroidectomy, or nutritional deficiencies that result in low serum calcium levels. Hypocalcemia increases the permeability of the lens capsule, disrupts the electrolyte balance within the lens, and interferes with lens metabolism.
Clinical Features
Patients typically present with three characteristic changes: tetany of the extremities, osteomalacia, and cataracts. In both eyes, there is radially or striated opacification in the anterior and posterior cortical regions of the lens, separated from the capsule by a transparent layer. Crystalline particles in red, green, or blue hues may also be observed beneath the lens capsule. The clouding gradually progresses to deeper cortical layers. In cases of intermittent hypocalcemia, layered opacities of the lens may develop, potentially advancing to complete cataracts or remaining in a stationary state.
Diagnosis
The diagnosis can often be supported by a history of thyroid surgery or nutritional disorders, along with clinical findings of low serum calcium, elevated serum phosphorus, and systemic and ocular manifestations.
Treatment
Adequate supplementation of vitamin D and calcium can help correct hypocalcemia and may slow the progression of cataracts.
When cataracts significantly impair vision, cataract extraction surgery may be performed. Hypocalcemia should be corrected prior to surgery. Bleeding tendencies during surgery require careful attention.