INTRODUCTION — Lens dislocation (ectopia lentis) in children may occur after trauma or in association with ocular or systemic disease. Dislocated lens in children will be discussed here. Cataracts and optical/visual rehabilitation of aphakic children are discussed separately. (See "Cataract in children".)
TERMINOLOGY — Subluxation is the term used when the lens is partially dislocated but remains attached to the ciliary body (figure 1) . Luxation is the term used when the lens is completely detached from the ciliary body. Luxated lenses may dislocate into either anterior or posterior chamber.
EPIDEMIOLOGY — The prevalence of dislocated lenses is not known .
ETIOLOGY — Lens dislocation (ectopia lentis) in children may occur after trauma or in association with ocular or systemic disease. It is important to determine the etiology because the associated disorders have different requirements for monitoring and/or therapy.
Trauma — Dislocation of the lens (picture 1) may occur after blunt trauma to the head, orbit, or eye . It occurs most commonly when the eye/orbit is hit directly with a high-energy projectile (eg, ball-bearing [BB], golf ball, baseball).
Lens dislocation may be associated with other ocular injury (eg, iris trauma, sphincter tear, anterior chamber angle recession, hyphema, cataract, vitreous hemorrhage, choroidal rupture, ruptured globe, and orbital fracture). (See "Orbital fractures" and "Open globe injuries: Emergency evaluation and initial management" and "Traumatic hyphema: Clinical features and diagnosis".)
Ocular causes — Ocular causes of ectopia lentis include simple ectopia lentis, ectopia lentis et pupillae, and aniridia.
●Simple ectopia lentis – Familial isolated ectopia lentis may be autosomal dominant (ectopia lentis 1, caused by mutation in the FBN1 gene [MIM #129600]) or autosomal recessive (ectopia lentis 2, caused by mutation in the ADAMTSL4 gene [MIM #225100]). ADAMTSL4 mutations seem to be the most common cause of isolated ectopia lentis . It may be present at birth or appear later in life. It is usually bilateral and progressive with superotemporal lens dislocation.
●Ectopia lentis with ectopia of pupil – Ectopia lentis with ectopia of pupil (ectopia lentis et pupillae [MIM #225200]) is a rare autosomal recessive condition also caused by mutation in the ADAMTSL4 gene. It is characterized by displacement of the pupil to a noncentral location (usually temporal) and displacement of the lens in the opposite direction. The pupil may be paracentral or near the limbus.
●Aniridia – Aniridia is a bilateral ocular condition manifested by a rudimentary iris, acquired cataract, lens dislocation, and hypoplasia of the optic nerve and fovea . It may be sporadic or inherited in an autosomal dominant fashion (MIM #106210) with complete penetrance but variable expressivity. The sporadic form can be associated with genitourinary problems (particularly Wilms tumor), intellectual disability, and deletion of the short arm of chromosome 11 (Wilms tumor, Aniridia, Genitourinary anomalies, and mental Retardation syndrome [WAGR]). (See "Presentation, diagnosis, and staging of Wilms tumor".)
Systemic causes — Systemic causes of ectopia lentis include Marfan syndrome, homocystinuria, sulfite oxidase deficiency, and Weill-Marchesani syndrome.
●Marfan syndrome – Marfan syndrome (MIM #154700), an autosomal dominant condition, is the most common systemic condition associated with ectopia lentis (picture 2). Ectopia lentis is present in 50 to 80 percent of cases. In approximately two-thirds of cases, subluxation is superior, but it may occur in any direction [4-6]. Other features include tall stature with increased arm span, arachnodactyly, mitral valve prolapse, aortic dilation and dissection, scoliosis, and hyperextensible joints. (See "Genetics, clinical features, and diagnosis of Marfan syndrome and related disorders", section on 'Ocular abnormalities'.)
●Homocystinuria – Homocystinuria (MIM #236200) is an autosomal recessive metabolic disorder associated with intellectual disability, chest deformities, osteoporosis, and increased risk of thrombotic episodes. Ectopia lentis occurs in 90 percent of patients, usually between 3 and 10 years of age. In approximately 60 percent of cases, subluxation is inferior or nasal [4,7] Patients with homocystinuria who require anesthesia should be admitted preoperatively for hydration and medical evaluation due to the high risk of thrombotic events .
●Sulfite oxidase deficiency – Sulfite oxidase deficiency (sulfocysteinuria, MIM #272300) is a rare, autosomal recessive cause of lens dislocation and intellectual disability. Sulfite oxidase converts sulfite to sulfate; deficiency of sulfite oxidase results in increased urinary sulfite. Additional clinical manifestations include delayed dental eruption and neurologic abnormalities . The diagnosis is confirmed by the absence of sulfite oxidase activity in skin fibroblasts.
●Weill-Marchesani syndrome – Weill-Marchesani syndrome is a connective tissue disorder that has both autosomal dominant (MIM #608328) and autosomal recessive (MIM #277600) forms . It is characterized by short stature, short limbs, joint stiffness, and lens abnormalities . In addition to lens dislocation, which occurs in 90 percent of cases, the lens may be microspherophakic (small and spherical with an increased anteroposterior thickness). Pupil block glaucoma is common and prophylactic laser iridotomy may be indicated.
CLINICAL FEATURES — Children with ectopia lentis usually present with complaints of poor or variable vision . Tremulousness of the iris (iridodonesis) occurs in most cases and is a helpful clinical sign . Lenses that are mobile beneath the iris can rub against the pigment epithelium and cause shedding of pigments, which can lead to pigmentary glaucoma. The pupil is small and may be difficult to dilate .
Additional clinical features depend upon the type and degree of dislocation.
●If the zonules (collagen fibers that hold the lens in place behind the iris) (figure 1) are uniformly loosened, the lens assumes a spherical shape (spherophakia). The focal point of the image occurs anterior to the retina (lenticular myopia). (See "Refractive errors in children", section on 'Myopia'.)
●If the zonular abnormality is localized to one area, the optical system is not perfectly spherical, and astigmatism results. (See "Refractive errors in children", section on 'Astigmatism'.)
●If the lens shifts off center, both myopia and astigmatism may result. Myopic astigmatism is best demonstrated with streak retinoscopy.
●If the dislocation is extensive, significant refractive shifts occur, particularly if the lens edge crosses the pupil aperture. In some cases, the lens may shift out of the pupillary aperture entirely (resulting in aphakia).
●Complete dislocation of the lens into the anterior chamber may cause acute angle closure glaucoma, a surgical emergency. (See "Overview of glaucoma in infants and children", section on 'Angle anomalies'.)
●Dislocation into the vitreous can cause retinal detachment.
In younger children, examination with a penlight may demonstrate tremulousness of the iris (iridodonesis).
After dilation of the pupils, the edge of the lens may be seen directly or on retroillumination. However, the pupil is often small and difficult to dilate, even with a combination of dilating agents .
If a child has a history of intermittent eye pain and a condition associated with lens subluxation, the eye pain may represent intermittent angle closure glaucoma secondary to lens subluxation into the anterior chamber. In this situation, dilation of the pupil and assessment for glaucoma should be performed by an ophthalmologist.
MANAGEMENT — Children with any type of subluxable or dislocated lens should be managed by an ophthalmologist. Depending upon the extent of dislocation, management may involve correction of myopic astigmatism, aphakia correction, or lensectomy/vitrectomy, or, in some cases, intraocular lens implantation.
Initially, spectacle correction is sufficient, but progressive lens dislocation results in significant refractive errors, which, if left untreated, will cause amblyopia. The eccentrically displaced lens results in myopic astigmatism that is difficult to completely correct .
When the lens is so displaced that the edge of the lens is in the pupillary aperture, optical correction becomes impossible, as one-half of the pupil is aphakic and the other one-half has a large degree of myopia and astigmatism.
If the best corrected visual acuity does not permit the child to function at the level necessary for normal activity and education, surgical removal of the lens may be warranted . Progressive lens dislocation has traditionally been managed conservatively . However, several case series suggest that satisfactory visual outcome may be obtained with surgical intervention [14-16].
Surgery — Surgery for ectopia lentis usually involves lensectomy/vitrectomy with optical rehabilitation with a contact lens. The inherent deficit in the lens capsule usually precludes implantation of an intraocular lens. The Artisan iris clip lens, which sits on the iris, is an alternative to contact lenses. It has been used in aphakic patients with encouraging results [17-19] but has not been used much in children. Alternatively, a scleral-sutured posterior intraocular lens may be used, but there is a definite risk of suture breakage over time. Another option is the use of a capsular tension ring combined with lens aspiration and in the bag placement of an intraocular lens . The capsular tension ring may provide additional support to the capsular bag and requires suturing to the sclera [21,22]. This procedure, however, carries a risk of further intraocular surgical intervention, with 15 percent of eyes requiring pars plana vitrectomy and posterior capsulectomy .
Most patients who undergo surgery for dislocated lens have a satisfactory visual outcome, with over 90 percent achieving visual acuity of 20/40 or better [1,14-16,23]. However, the risk of long-term complications (eg, retinal detachment and glaucoma) have not been well determined .
SUMMARY AND RECOMMENDATIONS
●Lens dislocation in children may occur after trauma or in association with ocular or systemic disease. It is important to determine the etiology because the associated disorders have different requirements for monitoring and/or therapy. (See 'Etiology' above.)
●Dislocation of the lens (picture 1) may occur after blunt trauma to the head, orbit, or eye, which may be associated with other ocular injury. Lens dislocation that occurs after minor trauma should prompt consideration of an underlying ocular or systemic condition. (See 'Trauma' above.)
●Ocular causes of ectopia lentis include simple ectopia lentis, ectopia lentis et pupillae, and aniridia. (See 'Ocular causes' above.)
●Systemic causes of ectopia lentis include Marfan syndrome (picture 2), homocystinuria, sulfite oxidase deficiency, Weill-Marchesani syndrome, and Ehlers-Danlos syndrome. (See 'Systemic causes' above.)
●Children with ectopia lentis usually present with complaints of poor vision. Tremulousness of the iris (iridodonesis) occurs in most cases and is a helpful clinical sign. Complete dislocation of the lens into the anterior chamber may cause acute angle closure glaucoma, which is a surgical emergency. (See 'Clinical features' above and "Overview of glaucoma in infants and children", section on 'Angle anomalies'.)
●The diagnosis of dislocated lens can be made by slit lamp examination (picture 1), penlight examination demonstrating iridodonesis (tremulousness of the iris), or by visualization of the edge of the lens after dilation of the pupil. (See 'Diagnosis' above.)
●Children with dislocated lens should be managed by an ophthalmologist. The goal of management is realization of full visual potential. Depending upon the extent of dislocation, management may involve correction of the refractive error, lensectomy/vitrectomy, and on occasion, intraocular lens placement. (See 'Management' above.)