Homocystinuria And Bilateral Ectopia Lentis – Perfect Timing For Surgery?: A Case Report

Ocular complications of homocystinuria include subluxation of lens, caused by the accumulation of cross-linked sulfhydryl groups in proteins such as elastin and the low levels of cysteine that weaken the lens zonules. Rupture of zonular fibers and lens displacement worsen with age and can lead to complete anterior dislocation with acute pupillary block glaucoma and trauma to the corneal endothelium. The purpose of this case report is to present a case of a bilateral anterior lens dislocation in a child with known homocystinuria and discuss the best possible surgery planning.

Pediatric ophtalmology department (CRI-OftaPed), Centro Hospitalar Universitário de Lisboa Central, Lisbon, Portugal

A 10-year-old boy had routine ophthalmology visits since the diagnosis of homocystinuria at age 8, presenting with bilateral infero-nasal lens subluxation. Correction surgery was contemplated but postponed as the last follow-up visit revealed a stable best corrected visual acuity (BCVA) of 20/40 for the right eye (OD) and 20/60 for the left eye (OS) and scored 3 at Jaeger chart for near vision.

Two months after the last follow-up visit, he presented with acute binocular pain, photophobia and vision loss. There was no history of trauma. Upon examination, BCVA was impossible to quantify due to poor collaboration. Slit-lamp examination revealed bilateral anterior lens luxation with visible ruptured zonular fibers, with diffuse ocular hyperemia, corneal oedema and narrow anterior chamber on OS. Pupillary block was not present. Fundus examination was unremarkable in both eyes. Repositioning of the lens behind the pupil was attempted with pharmacological mydriasis and dorsal decubitus, being successful only on the right eye. Our patient underwent bilateral sequential surgery under general anesthesia (left eye first) with lensectomy, anterior vitrectomy and implantation of an iris-fixated intraocular lens. There was no complication during the procedure.

Anterior lens dislocation is a frequent complication in homocystinuria patients with chronic lens subluxation. Lensectomy and refractive correction are inevitable, but perfect timing is difficult to determine. It is important to act before anterior lens luxation can traumatize corneal endothelial cells and cause permanent damage. On the other hand, premature surgery may be associated with greater surgical risks and less predictable refractive outcomes in a child.