Nontraumatic bilateral inferior ectopia lentis

An11-year-old myopic boy with left esotropia and amblyopia and no previous ocular and head trauma presented with deteriorating vision and bilateral lens subluxation causing index myopia and astigmatism. His right best-corrected visual acuity (BCVA) had declined from 6/12 to 6/18 (spherical equivalent [SE] −10.75 D), and left BCVA remained 6/36 (SE −9.00 D). Examination showed bilateral marked phacodonesis of crystalline lenses subluxed inferiorly [Figures 1 and 2]. Bilateral vitreolensectomies were performed with postoperative aphakia and contact lenses (CLs) correction, with a recovery of BCVA to 6/7.5 right (SE +13.00) and final left VA 6/50 (SE +12.50) at 1 year. Systemic workup showed mild learning disabilities only.

Figure 1:

Right eye anterior segment photographs showing marked phacodonesis of right crystalline lens dislocated inferiorly

Figure 2:

Left eye anterior segment photographs showing marked phacodonesis of left crystalline lens dislocated inferiorly

Questions

1. What is the most likely diagnosis based on history, examination, and systemic findings?

2. What systemic and ocular disorders need to be considered in the differential diagnosis?

3. What are the management options?

Answers for Clinical Quiz

Answers

1. Homocystinuria.

2. Marfan syndrome, Weill–Marchesani syndrome, Ehlers–Danlos syndrome, Sturge–Weber syndrome, aniridia, congenital glaucoma, Axenfeld–Rieger syndrome, retinitis pigmentosa, megalocornea, and pseudoexfoliation syndrome.

3. Stable correction of refractive error (RE) with spectacles or CLs, bilateral vitreolensectomies with postoperative aphakia and RE correction with spectacles or CLs, or bilateral vitreolensectomies and intraocular lenses (IOLs) implant with different techniques (scleral-fixated IOL and anterior or retropupillary iris–claw IOL).

Discussion

Ectopia lentis (EL) is a hereditary or acquired displacement of the crystalline lens due to defective zonular filaments. EL may be secondary to trauma,[1] inflammation, or hypermature cataract; however, genetic etiologies account for up to 80% of cases.

Homocystinuria caused by cystathionine-β-synthase deficiency is an autosomal recessive disorder, resulting in elevated homocysteinemia. Bilateral EL is the main ocular feature in 90% of patients, with decreased zonular integrity resulting from the enzymatic defect, and lenses are usually displaced inferonasally. Systemic findings include intellectual disability, skeletal abnormalities, and increased risk of thrombosis.[2]

The management of EL remains challenging to maximize BCVAs, prevent amblyopia, and correct RE with spectacles, CLs, or IOLs implants. Pars plana vitrectomy is an established treatment for eyes with rhegmatogenous retinal detachment (including challenging cases complicated by proliferative vitreoretinopathy) and with vitreoretinal interface syndrome and with aqueous misdirection.[3,4,5,6] but less so for different conditions.[7,8,9,10] Anterior iris–claw or retropupillary iris–claw IOL implant after vitreolensectomy has been suggested in EL eyes without capsular support;[11,12] decrease in the average endothelial cells density and cystoid macular edema are the main long-term complications described. Alternative techniques include scleral-fixated IOLs (postoperative increase in BCVAs in 83% of treated eyes and high incidence of residual RE in 94% of operated eyes have been reported)[13] and transscleral fixation of capsular bag with capsular tension ring and IOL into the bag (postoperative increase in BCVAs in 78.5% of treated eyes and incidence of posterior capsule opacification in 52% of operated eyes have been reported).[14]

Homocystinuria should be suspected in young children presenting with bilateral inferior EL and learning disabilities. We recommend early surgical treatment if adequate or stable correction of RE is impaired to minimize the risk of amblyopia.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.