Unilateral and Spontaneous Complete Anterior Dislocation of the Crystalline Lens in a Patient With Homocystinuria

Homocystinuria is a metabolic disorder caused by a deficiency of cystathionine beta-synthase with autosomal recessive inheritance. Clinically it is characterized by lens subluxation, skeletal abnormalities, and thromboembolic accidents. We present a 6-year-old boy who was a known case of homocystinuria. The patient had a previous history of thrombotic cerebrovascular infarction at the age of 3. He had mild and vague pain in the left eye two weeks before presentation without being exposed to trauma. Ophthalmic examination revealed the dislocation of the crystalline lens into the anterior chamber with diffuse corneal stromal edema in the affected eye. The patient was treated with topical atropine and betamethasone eye drops, but due to the corneo-lenticular contact and corneal edema, he underwent lens extraction and placement of iris-fixated intraocular lens after 48 hours. Corneal edema exhibited improvement at follow-up visits. Early age onset and unilateral complete lens dislocation to the anterior chamber in the absence of a history of trauma is a less common presentation of homocystinuria. In patients with systemic diseases including homocystinuria that cause zonulysis, lens dislocation is usually symmetric and bilateral. Nevertheless, in unilateral cases especially in those who did not have any history of trauma, evaluation for systemic diseases like homocystinuria is necessary for early diagnosis and prevention from other systemic involvements.