Ectopia lentis is defined as displacement or malposition of the crystalline lens of the eye.[1, 2, 3]
Berryat described the first reported case of lens dislocation in 1749, and Stellwag subsequently coined the term ectopia lentis in 1856 (describing a patient with congenital lens dislocation).
The lens is considered dislocated or luxated when it lies completely outside the lens patellar fossa, in the anterior chamber, free-floating in the vitreous, or directly on the retina. The lens is described as subluxed when it is partially displaced but contained within the lens space. In the absence of trauma, ectopia lentis should evoke suspicion for concomitant hereditary systemic disease or associated ocular disorders.[4, 5]
Disruption or dysfunction of the zonular fibers of the lens, regardless of cause (trauma or heritable condition), is the underlying pathophysiology of ectopia lentis. The degree of zonular impairment determines the degree of lens displacement.
Ectopia lentis is a rare condition. Incidence in the general population is unknown. The most common cause of ectopia lentis is trauma, which accounts for nearly one half of all cases of lens dislocation.
Mortality/Morbidity
Ectopia lentis may cause marked visual disturbance, which varies with the degree of lens displacement and the underlying etiologic abnormality.
Sex
Males appear more prone to ocular trauma than females; therefore, a male preponderance has been reported. Male and female frequency varies with the etiology of the lens displacement.
Age
Ectopia lentis can occur at any age.[6] It may be present at birth, or it may manifest late in life.
Patients with ectopia lentis associated with a heritable condition need to be educated on the importance of following up with a primary care physician to rule out life-threatening disorders.
Safety glasses are advocated when risk of eye injury is possible.
Common presenting symptoms (visual disturbance) include the following:
Red painful eye (secondary to trauma)
Decreased distance visual acuity (secondary to astigmatism or myopia)
Poor near vision (loss of accommodative power)
Monocular diplopia
Determine if there is a history of ocular trauma.
Obtain a detailed history investigating possible systemic disease associations, as follows:
Cardiovascular disease (eg, Marfan syndrome)
Skeletal problems -Marfan syndrome, Weil-Marchesani syndrome, or homocystinuria
Pertinent family history - Consanguinity, mental retardation, or unexplained deaths at young age (eg, autosomal recessive conditions, including homocystinuria, hyperlysinemia, ectopia lentis et pupillae,[7] or sulfite oxidase deficiency)
A pediatrician or an internal medicine physician should perform a comprehensive physical examination of patients with ectopia lentis of undetermined etiology because of the commonly associated hereditary systemic disorders.
The ocular examination should include the elements listed below.
Vision
Ectopia lentis is potentially visually debilitating.
Visual acuity varies with the degree of malpositioning of the lens.
Amblyopia is a common cause of decreased vision in congenital ectopia lentis and is preventable and treatable.
External ocular examination
Attention to orbital anatomy is important to evaluate for hereditary malformations (eg, enophthalmos with facial myopathic appearance seen in patients with Marfan syndrome).[8]
Measure corneal diameter (megalocornea is associated with Marfan syndrome).
Strabismus is not uncommon (secondary to amblyopia).
Retinoscopy and refraction
Careful retinoscopy and refraction is essential, often revealing myopia with astigmatism.
Keratometry may help ascertain degree of corneal astigmatism.
Slit lamp examination
Evaluate lens position, and identify phacodonesis or cataract.
Measure intraocular pressure. Elevation may indicate secondary glaucoma. Causes of glaucoma in ectopia lentis include the following: (1) pupillary block, (2) phacoanaphylaxis or phacolytic, (3) posttraumatic angle recession, (4) poorly developed angle structures, and (5) lens in the anterior chamber.
Dilated fundus examination
Retinal detachment is one of the most serious consequences of a dislocated lens.
The numerous causes of ectopia lentis are discussed below.
Traumatic dislocation
Traumatic dislocation is the most common cause.
Hereditary ectopia lentis without systemic manifestations
Single (isolated) ectopia lentis is characterized by autosomal dominant inheritance with the genetic defect located on chromosome 15, causing a dysfunctional zonular apparatus. Microspherophakia is common. Although most often present at birth, late onset has been described. Typically, the lens is displaced supertemporally.
Ectopia lentis et pupillae is characterized by asymmetric eccentric pupils that are displaced in the opposite direction of the lens dislocation (toward the most dysfunctional zonular fibers). The condition usually is bilateral and typically autosomal recessive. The irides often appear atrophic with transillumination defects on slit lamp examination.[7] Cataracts commonly are seen.[9]
Systemic conditions commonly associated with ectopia lentis
Marfan syndrome is the most frequent cause of heritable ectopia lentis. The syndrome is transmitted as an autosomal dominant trait with variable expressivity and has a prevalence of approximately 5 per 100,000. Several point mutations involving the fibrillin gene on chromosomes 15 and 21 have been described and may relate to incompetent zonular fibers. Salient features of Marfan syndrome include tall stature, arachnodactyly, joint laxity, mitral valve prolapse, aortic dilatation, axial myopia, and increased incidence of retinal detachment. Lens dislocation occurs in about 75% of patients with Marfan syndrome and usually is bilateral, symmetrical, and supertemporal.[10]
View Image
Ectopia lentis. Supertemporal dislocation of a lens in the right eye of a patient with Marfan syndrome. Note the attached zonular fibers.
Homocystinuria is the second most common cause of hereditary ectopia lentis. It is an inborn error of metabolism most often caused by a near absence of cystathionine b-synthetase (the enzyme that converts homocysteine to cystathionine). Patients typically have fair skin with coarse hair, osteoporosis, mental retardation (nearly 50%), seizure disorder, marfanoid habitus, and poor circulation. Thromboembolic events constitute the major threat to survival, especially following general anesthesia. Lens luxation usually is bilateral, symmetrical, and inferonasal, and presents in nearly 90% of patients. Deficient zonular integrity secondary to the enzymatic defect has been implicated as the primary cause of lens displacement.
Weil-Marchesani is a rare syndrome characterized by skeletal malformations (eg, short stature, brachycephaly, limited joint mobility, well-developed muscular appearance) and ocular abnormalities (eg, ectopia lentis, microspherophakia, lenticular myopia). The inheritance pattern is not well understood. Microspherophakia is the most prominent feature of this syndrome. High incidence of lens subluxation occurs inferiorly, often progressing to complete dislocation. Pupillary block glaucoma is common; therefore, prophylactic laser peripheral iridotomies are recommended.[11]
View Image
Ectopia lentis. Microspherophakia and spontaneous inferior dislocation of a lens in a patient with Weil-Marchesani syndrome.
Sulfite oxidase deficiency is an extremely rare disorder caused by a defect in sulfur metabolism. Salient features include progressive CNS abnormalities that develop within the first year of life in concert with ectopia lentis.
Hyperlysinemia is an extremely rare autosomal recessive enzymatic defect of amino acid metabolism that is characterized by mental retardation and lens dislocation. Diagnosis is made by demonstration of increased plasma levels of lysine.
Primary ocular disorders associated with ectopia lentis
These include the following:
Congenital glaucoma/buphthalmos
Pseudoexfoliation syndrome
Syphilis/chronic uveitis
Retinitis pigmentosa
Megalocornea
Aniridia
Hypermature cataract
Intraocular tumor
High myopia
Systemic diseases rarely associated with ectopia lentis
These include the following:Ehlers-Danlos syndrome
The most common ocular complications of ectopia lentis include amblyopia, uveitis, glaucoma, and retinal detachment; appropriate treatment for these specific entities should be implemented.
Perform appropriate diagnostic and laboratory evaluation, if a hereditary condition is suspected (eg, cardiac evaluation for Marfan syndrome, check serum and urine levels of homocysteine or methionine for homocystinuria).
Without an antecedent history of trauma, patients with ectopia lentis may possess a systemic disease with potentially deleterious effects; therefore, comanagement with the patient's pediatrician or internist is essential. Dietary restriction may be partially effective in patients with homocystinuria. Repair of an impending dissecting aortic aneurysm in Marfan syndrome may be life saving. If a hereditary condition is discovered, appropriate genetic counseling should be given. Moreover, all relatives with potential risk should be examined.
Treatment of glaucoma is dependent on the etiologic mechanism.
In pupillary block (eg, patients who have Weil-Marchesani with microspherophakia), laser peripheral iridotomy or iridectomy should be performed, and intraocular pressure elevation should be treated medically. Prophylactic laser iridotomy in patients with microspherophakia is beneficial.
Treatment of a lens dislodged into the anterior chamber is initially pharmacological with mydriasis/cycloplegia (to permit posterior migration of the lens behind the iris) in conjunction with ocular massage through a closed lid to promote this posterior migration. Surgical treatment will then be needed to prevent further complications.
Treatment of a dislocated lens in the vitreous is surgical; however, many vitreoretinal surgeons may advocate observation if no visual disturbance or impending retinal complication is apparent.
Charles W Eifrig, MD, Vitreoretinal Surgeon, Retina Associates of Orange County
Disclosure: Nothing to disclose.
Specialty Editors
Simon K Law, MD, PharmD, Clinical Professor of Health Sciences, Department of Ophthalmology, Jules Stein Eye Institute, University of California, Los Angeles, David Geffen School of Medicine
Disclosure: Nothing to disclose.
J James Rowsey, MD, Former Director of Corneal Services, St Luke's Cataract and Laser Institute
Disclosure: Nothing to disclose.
Chief Editor
Hampton Roy, Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences
Disclosure: Nothing to disclose.
Additional Contributors
Richard W Allinson, MD, Associate Professor, Department of Ophthalmology, Texas A&M University Health Science Center; Senior Staff Ophthalmologist, Scott and White Clinic
Disclosure: Nothing to disclose.
Acknowledgements
The authors and editors of Medscape Reference gratefully acknowledge the contributions of previous coauthor, David E Eifrig, MD, to the development and writing of this article.
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