Woman presents with 1-year history of worsening blurred vision in left eye
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A 42-year-old woman presented to Lahey Hospital and Medical Center for 1 year of progressively worsening blurred vision in the left eye.
She also reported occasional stabbing pain in her left eye, especially when attempting to read or looking downward, as well as seeing translucent floaters in both eyes that were more noticeable in bright lights.
The patient had no medical history and did not take any medications. Social history was noncontributory. Ocular history included myopic LASIK surgery more than a decade before presentation.
Examination
On examination, the patient’s best corrected visual acuity was 20/20-1 in the right eye and count fingers at 3 feet, which improved to 20/70 with pinhole. IOP was 10 mm Hg and 11 mm Hg in the right and left eyes, respectively. Pupils were normal and without afferent pupillary defect. Confrontational visual fields and extraocular movements were full.
Anterior examination in the right eye was unremarkable with the exception of trace posterior subcapsular cataract. In the left eye, the anterior chamber was noted to be very shallow (Figure 1) and demonstrated phacodonesis. Posterior subcapsular cataract was also noted in the left eye. On gonioscopy of the left eye, there were some areas of visible pigmented trabecular meshwork, but the iris was extremely anteriorly bowed (Figure 2). The dilated fundus exam of both eyes was unremarkable, with flat retina free of any breaks or tears.
Testing
When the patient was autorefracted, the right eye was +1.00 –0.25 × 097; however, the left eye was unable to be measured. When manifest refraction was performed, the right eye had a prescription of +0.5 and spherical; the left eye was –4.00 –1.00 × 085 and corrected to 20/60. Color fundus photos (Figure 3) were obtained and demonstrated normal-appearing retina, although the left eye appeared to have media opacification. OCT (Figure 4) showed normal foveal contour and no abnormal appearance of the inner or outer retinal layers; however, the left eye similarly showed slightly decreased signal transmission diffusely. B-scan ultrasonography was unremarkable and without evidence of mass or detachment.
What is your diagnosis?
Worsening blurred vision
The patient was diagnosed with spontaneous anterior lens dislocation of the left eye. Biometry performed at the time of IOL calculations demonstrated clear anterior dislocation of the left crystalline lens (Figure 5). The episodes of occasional significant left eye pain elicited with reading and leaning head down were thought to be attributed to intermittent subacute angle closure from the dislocated lens. Upon further investigation, it was revealed that the patient had a strong family history of Marfan syndrome, although she did not have suggestive features; the patient was of average height and did not have significant joint laxity nor a highly arched palate. She additionally had no history of cardiac abnormalities and had not received any kind of workup nor genetic testing up to this point.
Management
Given the concern for acute angle closure of the left eye, the patient was counseled to avoid dimly lit lighting conditions and use of cold medicines and antihistamines. She was referred to see a glaucoma specialist for a laser peripheral iridotomy of the left eye to mitigate the risk for angle closure secondary to pupillary block. Definitive surgical management with cataract extraction and possible pars plana vitrectomy was planned given the shallowness of the anterior chamber.
One month later, the patient underwent cataract extraction and IOL insertion by intrascleral haptic fixation (Yamane technique). Intraoperatively, there was extensive zonular loss (approximately 270°), and capsular bag instability was noted, requiring placement of three capsule hooks before proceeding with phacoemulsification. A combined pars plana vitrectomy with endolaser was performed for an incidentally found small retinal hole at 12 o’clock, with removal of the capsular bag. The surgery was well tolerated and completed without complication. At the 1-month postoperative appointment, vision was 20/30 in the left eye, and the patient was healing well.
Discussion
Ectopia lentis is the displacement of the native crystalline lens. Radially oriented zonular fibers extend from the lens to the ciliary body band and are the primary support structure that maintains the centered position of the lens within the visual axis. Ectopia lentis is most commonly caused by trauma; however, several systemic disorders predispose patients to this condition.
When blunt force trauma to the eye (and in some cases the head) occurs, rapid deformation of the globe can cause expansion at the equator. The radially oriented zonules are at risk of damage when such an insult occurs. Clinical suspicion for systemic disorders should be raised when lens dislocation occurs in the case of minimal or no trauma.
The most common systemic disorders associated with ectopia lentis are Marfan syndrome, homocystinuria and Weill-Marchesani syndrome, although this list is not exhaustive. Briefly, Marfan syndrome is an autosomal dominant disorder caused by mutations in the FBN1 gene, which encodes for fibrillin-1, a structural macromolecule in connective tissue. Characteristic features include tall stature and long limbs, extreme joint flexibility, mitral valve prolapse and aortic root aneurysm. In the eyes, myopia frequently occurs, and lens dislocation is common as the zonular fibers are principally composed of polymerized fibrillin. Homocystinuria is an inherited metabolic disorder caused by a deficiency of cystathionine beta-synthase activity that results in abnormally high levels of methionine and homocysteine. Patients may have a similar body habitus as those with Marfan syndrome, although they can also present with a history of thromboembolism and development delay. Despite a fundamentally dissimilar etiology, homocystinuria shares many similarities with Marfan syndrome due to the disruption of the function of fibrillin in the presence of high concentrations of homocysteine. Lastly, Weill-Marchesani syndrome is a connective tissue disorder that is conversely characterized by short stature, brachydactyly and brachycephaly, in addition to ocular manifestations such as ectopia lentis. It is typically driven by mutations in the ADAMTS10 or, less commonly, FBN1 genes, although its pathomechanism leading to ectopia lentis is not fully understood.
In all patients suspected of ectopia lentis, a thorough history including family history and physical examination are indicated. The degree of lens dislocation may be classified based on how far the lens edge is visible within a dilated pupil. While systemic workup is ongoing, management is directed at the complications of the dislocated lens. Mild zonular instability resulting in a lens that remains within the visual axis may require only refractive correction. Dislocation into the anterior chamber may warrant mydriatic drops to promote lens repositioning within the posterior chamber. In patients where the degree of dislocation is severe enough to cause pupillary block, referral for a laser peripheral iridotomy is indicated. Otherwise, elevations in IOP may be managed with topical medications. Optimal surgical management is not universally agreed upon, and individual, case-based factors should inform subsequent management. As the lens-capsular bag complex is inherently unstable, several strategies have been employed to increase stability or circumvent the need to use the capsular bag, including use of capsular retractors or tension rings, as well as iris or scleral fixated IOLs. Lensectomy and vitrectomy may be indicated in the case of posterior displacement of the lens into the vitreous chamber, especially when accompanied by concomitant retinal detachment.
- For more information:
- Edited by Jonathan T. Caranfa, MD, PharmD, and Angell Shi, MD, of New England Eye Center, Tufts University School of Medicine. They can be reached at jcaranfa@tuftsmedicalcenter.org and ashi@tuftsmedicalcenter.org.
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