Woman presents with gradually worsening vision
Both eyes featured 360° corneal pannus with multiple Salzmann's nodules and diffuse punctate epithelial erosions.
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A 45-year-old woman presented to the New England Eye Center comprehensive ophthalmology clinic for evaluation of gradually worsening blurry vision in both eyes over the past 1 to 2 years.
The blurry vision was associated with worsening glare under bright light conditions. She also had occasional eye irritation and foreign body sensation, worse in the right eye. She did not have diplopia, new floaters, flashes or a curtain over her vision.
Her ocular history included congenital aniridia and bilateral strabismus surgery. She was previously followed at an outside clinic where she had normal glaucoma testing 2 years ago but had not been seen recently. She was otherwise healthy and had a history of a cesarean section. She worked as a teacher, did not smoke and drank alcohol occasionally. Her family history was significant for two sons with aniridia.
Examination
On examination, the patient’s best corrected visual acuities were 20/400 in the right eye and 20/200 in the left eye. Pupil exam showed iris stumps in both eyes that were not reactive to light. IOPs were 18 mm Hg bilaterally. Confrontation visual fields were full. Extraocular movements were full; nystagmus was present. She correctly identified all of the Ishihara color plates in both eyes.
Source: Teresa P. Horan, MD, and Helen K. Wu, MD
Anterior segment exam was notable for 360° corneal pannus with multiple Salzmann’s nodules and diffuse punctate epithelial erosions in both eyes (Figure 1). The Salzmann’s nodules involved the central visual axis in the left eye. No frank epithelial defects were noted. She had bilateral 1+ nuclear sclerotic, 3+ cortical spoking and 1+ posterior subcapsular cataracts. There was slight superior displacement of bilateral lenses, more in the right eye than the left, without evidence of phacodonesis. Gonioscopy showed the angle open to the ciliary body band in both eyes with 360° of residual iris stump. The view was hazy on dilated fundus examination, but both optic nerves were pink with sharp margins and a 0.45 cup-to-disc ratio. The retina appeared flat. Ultrasound biomicroscopy of both eyes demonstrated iris hypoplasia (Figure 2).
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Worsening vision
The differential for progressive worsening vision in this patient with aniridia is broad.
The patient’s cataracts were significant and could explain her decreased vision and glare symptoms. In addition, the keratopathy and Salzmann’s nodules were likely affecting her vision, especially given the Salzmann’s nodules located in the visual axis of the left eye. Corneal pannus in both eyes with an irregular epithelium made aniridia-associated keratopathy a possibility. In the setting of aniridia, superior displacement of the lens could affect the optical system of her eyes, causing aberrations perceived as worsening vision and glare. This lens displacement associated with aniridia is thought to be due to molecular changes in the zonules. Although the posterior pole was difficult to evaluate due to the hazy view, she likely had underlying foveal hypoplasia in the setting of her aniridia.
Case continued
The patient was referred to the cornea department and underwent cataract extraction and IOL implantation with superficial keratectomy in both eyes. Pathology of corneal specimens from both eyes showed Salzmann’s nodular degeneration and stromal fibrosis. On postop day 1 in both eyes, she had large epithelial defects that healed by the first postoperative week with a bandage contact lens (BCL) in place. The corneal epithelium remained intact until postop month 1 when she developed a new epithelial defect in the right eye. The following month, she had two epithelial defects in each eye, requiring an amniotic membrane in the right eye for central epithelial defects and a BCL in the left eye for peripheral defects. These resolved but recurred again 1 week later, requiring BCLs in both eyes.
This cycle occurred for several months with persistent epithelial defects in both eyes that required amniotic membranes. The patient was started on autologous serum tears. The epithelium healed first in the left eye, and visual acuity improved to 20/70 with a scleral lens. She required multiple amniotic membranes for the right eye with vision deteriorating to counting fingers at its worst. Eleven months after cataract surgery, her epithelium was stable enough for scleral lenses in both eyes. Her most recent exam, now 3 years after surgery, showed visual acuities of 20/200 in the right eye and 20/100 in the left eye. Her near vision improved to 20/50 in the left eye. Slit lamp exam showed inferior displacement of the IOL in the right eye, which was stable since 1 year after cataract surgery. There were no epithelial defects. However, the epithelium appeared whorled with 360° of neovascularization in both eyes, encroaching centrally in the right eye.
Discussion
Congenital aniridia is a rare panocular disorder that can cause iris and foveal hypoplasia. Secondary complications include nystagmus, cataract, keratopathy and glaucoma. The prevalence is about 1:64,000 to 1:96,000. Congenital aniridia is caused by a mutation in the PAX6 gene, which regulates eye development. Two-thirds of cases are due to autosomal dominant inheritance, and one-third are sporadic. Aniridia can be an isolated disorder or associated with WAGR or Gillespie syndromes.
Patients with aniridia can have poor vision due to foveal hypoplasia, although later in life they can develop worsening visual acuity due to progressive aniridia-associated keratopathy (AAK). Symptoms of AAK include dry eye, redness, photophobia and epiphora. The incidence increases with age and is projected to be up to 90% of patients with aniridia. AAK is caused by deficiency of limbal stem cells as well as impaired epithelial cell adhesion, migration and differentiation.
First, conjunctivalization and vascularization occur in the peripheral cornea, which slowly advance onto the central cornea. Lopez-Garcia and colleagues classified AAK into three phases: slight limbal insufficiency that involves two erosions or ulcers within 6 months with vascular pannus no more than 1 mm from the limbus; moderate limbal insufficiency that includes three or more erosions or ulcers within 6 months with vascular pannus involving at least the peripheral half of the cornea; and severe limbal insufficiency that shows permanent signs of corneal erosion and pannus involving the central cornea. Clinically, patients with AAK have recurrent erosions, corneal ulceration, chronic pain and decreased vision. Our patient likely had AAK given her history of recurrent erosions and decreased vision. AAK may be exacerbated after surgery that involves manipulation of the limbus, as in our patient, or after application of topical antimetabolites.
Management depends on the severity of AAK. Mild disease can be treated with supportive therapy such as lubricants. Moderate disease can be treated with autologous serum drops or temporary amniotic membrane transplants to support the limbal stem cells. Severe disease may require limbal stem cell transplantation. Penetrating keratoplasty is ineffective as corneal decompensation recurs due to limbal stem cell insufficiency. The Boston keratoprosthesis has been successful in a small study. Although aniridia and its associated keratopathy are rare, it is important to recognize the corneal findings and manage them appropriately to avoid further vision loss.
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- For more information:
- Teresa P. Horan, MD, and Helen K. Wu, MD, can be reached at New England Eye Center, Tufts University School of Medicine, 800 Washington St., Box 450, Boston, MA 02111; website: www.neec.com.
- Edited by Christine Benador-Shen, MD, and Malgorzata Dymerska Peterson, MD. They can be reached at New England Eye Center, Tufts University School of Medicine, 800 Washington St., Box 450, Boston, MA 02111; website: www.neec.com.