To report a case of late diagnosis of a classical familial homocystinuria based on an ophthalmologic examination. A 35-year-old male with Marfan-like phenotype complained of a progressive increase of myopia during the previous 2 years. Ophthalmologic exploration showed a bilateral subluxation of the lens with inferior and nasal displacement. Biochemical study detected a profile of increased amino acid levels (homocysteinemia) consistent with suspected homocystinuria. Vascular and skeletal studies ruled out Marfan syndrome. Response to treatment demonstrated B(6)-non-responsive homocystinuria. Molecular study showed compound heterozygous T353 N and D444 N mutations of the cystathionine beta-synthase (CBS) gene, and also a C667T homozygous mutation of the methylenetetrahydrofolate-reductase (MTHFR) gene. Family study showed classical homocystinuria in his father and sister, although they did not present any systemic or ocular features of the disease. Homocystinuria is a metabolic disease usually presenting at an early age as vascular, skeletal and neuropsychiatric abnormalities, as well as ectopia lentis. Our case is atypical because of the absence of thromboembolism and the mild phenotype, in spite of being B(6)-non-responsive, and the association of a rare compound heterozygous mutation of the CBS gene and also an homozygous mutation of the MTHFR gene. It is necessary to rule out homocystinuria in patients with ectopia lentis, even in the absence of systemic symptoms.

The risk of visual loss after nonocular surgeries is very low, between 0.2% and 4.5%. According to the American Society of Anesthesiologists, ischemic optic neuropathy has been reported mostly after spinal surgery (54.2%), followed by cardiac surgery and radical neck dissection (13.3%). It may occur in association with some conditions that include systemic hypotension, acute blood loss and hypovolemia. Case report: A 46-year-old woman, whose diagnosis was laryngeal squamous cell carcinoma, complained of visual loss in her right eye two days after surgery (laryngectomy with bilateral radical neck dissection and left jugular ligature) and one day later in her left eye. The diagnosis was nonarteritic anterior ischemic optic neuropathy. Conclusion: Anterior ischemic optic neuropathy related to nonocular surgery is usually bilateral and its prognosis is very poor, resulting in blindness or severe visual loss. Although rare, patients should be warned about this complication, which has a profound impact on quality of life, since no therapeutic measure, including correction of hypotension and anemia, seems to improve the prognosis of this complication.