BILATERAL SPONTANEOUS ANTERIOR LENS DISLOCATION AS THE INITIAL PRESENTATION OF HOMOCYSTINURIA

To report a case of bilateral spontaneous anterior dislocation of the crystalline lens as the initial presentation of homocystinuria in a young male patient.

B Department, Hedi Rais Institute of Ophthalmology, Tunis, Tunisia. 

Case report

A 32-year-old male presented to our department with acute ocular pain in his left eye (LE) and severe headache. There was no history of trauma. Visual acuity (VA) was limited to counting fingers. Slit-lamp examination revealed mild conjunctival hyperemia and diffuse corneal stromal edema. The LE lens dislocated into the anterior chamber (AC),and the right one had stretched zonular fibers with inferior subluxation. Intraocular pressures (IOP) were 67mmHg and 15mmHg in the LE and right eye(RE), respectively. Fundus examination was unremarkable in the RE. The initial management included anti-glaucoma (dorzolamide, timolol, brimonidine) and dexamethasone eye drops. He was positioned supine and given analgesia and intravenous mannitol 1g/kg. Subsequently, his LE IOP dropped to 24 mmHg. The following morning, the patient underwent urgent lens extraction with anterior vitrectomy under general anesthesia and was left aphakic. At one-week follow-up, the patient reported an improvement of blurred vision and pain in the LE. The VA was 6/60 in the LE. The IOP was 14mmHg. Slit lamp examination demonstrated mild conjunctival hyperemia and clear cornea. Fundus examination of the same eye revealed superior temporal branch retinal vein occlusion. The patient agreed to elective RE lens extraction and implantation of an intraocular lens. Secondly, we scheduled iris-claw implantation in his LE. Two weeks later, the patient re-attended the emergency department, this time for severe pain in his RE. The lens has displaced into the AC. The IOP was 60mmHg. He again was admitted to the ophthalmic ward. The patient was treated with the same pharmacological regime as described previously. His IOP decreased to 20mmHg. The following day he underwent a lens extraction, anterior vitrectomy without implantation. These findings were consistent with the diagnosis of bilateral ectopia lentis, secondary to classical homocystinuria. The patient was reffered to internal medicine department for further investigations. His serum homocysteine levels were 200 mmol/l (reference range < 10 mmol/l). He was started on pyridoxine and advised intake of methionine restricted diet. A week later, he presented left lower extremity deep venous thrombosis.

In the absence of trauma, ectopia lentis should elicit a search for an underlying hereditary or systemic cause. In these cases, homocystinuria must be considered. Lens subluxation is usually posterior, bilateral, and inferonasal. Bilateral anterior dislocation is rare. Homocystinuria management requires collaboration between ophthalmologists and internists to prevent serious general and ocular complications.