Ectopia Lentis

Ectopia lentis is congenital or acquired displacement of the lens from its central position caused by abnormal or absent zonular fibres. In children it is usually inherited.

• Simple ectopia lentis (isolated): autosomal dominant FBN1 variants or autosomal recessive ADAMTSL4 variants; displacement is typically upward or temporal and bilateral, often symmetric.
• Ectopia lentis et pupillae: autosomal recessive; lens and pupil displaced in opposite directions, with slit like pupil and persistent pupillary membrane remnants.
• Systemic syndromes: Marfan syndrome (about 60 percent have ectopia lentis, superotemporal), homocystinuria (inferonasal, in over 90 percent by age 15), Weill-Marchesani syndrome (microspherophakia, anteriorly displaced lens, short stature, brachydactyly), sulphite oxidase and molybdenum cofactor deficiency, Ehlers-Danlos syndrome, hyperlysinaemia, Stickler syndrome, and aniridia.
• Acquired: trauma, pseudoexfoliation, hypermature cataract, uveitis, intraocular tumour, and high myopia.

• Reduced vision from high lenticular astigmatism, myopia and, in aphakic zones, high hypermetropia; amblyopia in children, strabismus.
• Iridodonesis and phacodonesis, deepened or asymmetric anterior chamber, visible lens margin within the dilated pupil, monocular diplopia.
• Microspherophakia: small spherical lens, lenticular myopia, pupillary block glaucoma.
• Associated: retinal detachment, glaucoma, cataract, high myopia.
• Systemic findings depend on the syndrome: tall stature, arachnodactyly, joint hypermobility, pectus excavatum, scoliosis, high arched palate (Marfan); thromboembolism, osteoporosis, developmental delay (homocystinuria).

• Dilated slit lamp examination, noting lens direction and the extent of zonular loss; ultrasound biomicroscopy.
• Cycloplegic refraction in children and axial length measurement.
• Systemic evaluation: echocardiogram (aortic root, mitral valve), plasma total homocysteine and methionine, urine nitroprusside test, FBN1 and ADAMTSL4 genetic testing, skeletal examination and Ghent criteria.
• Family examination and genetic counselling.

• Refractive correction using spectacles or contact lenses (phakic or aphakic portion) and amblyopia therapy (patching of the better eye 2 to 6 hours daily) in children. Aim to preserve the lens while visual development continues.
• Monitor annually for retinal detachment, glaucoma and cataract; advise to avoid contact sports and eye trauma.
• Surgery when optical correction fails or complications develop: pars plana lensectomy and vitrectomy (children), or phacoemulsification with capsular tension ring and segments in adults, then in-the-bag, scleral fixated (sutured or flanged intrascleral) or iris claw lens; in children, leave aphakia corrected with contact lenses until an intraocular lens can be placed (typically after early childhood).
• Perioperative care in homocystinuria: pyridoxine 200 to 1000 mg daily, betaine 100 mg/kg daily, folate 5 mg daily, hydration, thromboprophylaxis, avoid nitrous oxide and prolonged fasting.
• Marfan: beta blocker (atenolol 50 to 100 mg daily) or losartan 50 to 100 mg daily and annual echocardiography.
• Pupillary block in microspherophakia: cycloplegia (atropine 1 percent daily) and laser peripheral iridotomy, avoid miotics.