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Woman presents with worsening vision, family history of similar problems
Slit lamp exam of both corneas found networks of refractile, branching, grayish white lines within the stroma.
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| Jane Loman | Zinaria Williams |
A 60-year-old woman presented to the New England Eye Center complaining of progressively worsening vision, greater in the right eye than left, for the past 6 months. She also reported light sensitivity, halos and glare in both eyes.
History
The patient’s ocular history was unremarkable. Her medical history included asthma, emphysema and osteoporosis. Her medications included TheraTears (Schepens Eye Research Institute), Singulair (montelukast sodium, Merck), Advair (fluticasone propionate/salmeterol, GlaxoSmithKline) and Protonix (pantoprazole sodium, Wyeth Pharmaceuticals). She was allergic to codeine, sulfur and erythromycin. Her family history was notable for a sister and father who had corneal transplants and a niece and nephew with similar corneal problems. She was retired, reported a 40-year smoking history and denied alcohol consumption.
Examination
On ophthalmic examination, the patient’s best corrected visual acuity was 20/25 in the right eye and 20/20 in the left eye. Her IOP, pupil reactivity, extraocular muscle movements and visual fields to confrontation were all normal. Her external exam was normal.
On slit lamp examination of the right cornea, there was a network of refractile, branching, grayish white lines within the stroma (Figure 1a). There were also similar findings in the left cornea but to a lesser extent (Figure 1b). Retroillumination of both eyes revealed a glassy, clear outline of the branching lines and subepithelial dots (Figure 2). The rest of the exam was unremarkable except for nuclear, cortical and posterior subcapsular cataracts, right eye greater than left.
| Color photographs of the right eye (1a) reveal a network of refractile, branching, grayish white lines within the stroma. The left eye (1b) has similar findings but to a lesser extent. | |
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Retroillumination of the right (2a) and left (2b) eyes shows a glassy, clear outline of the branching lines, as well as subepithelial dots. Images: Nguyen MHT, Wu H | |
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What is your diagnosis?
Corneal findings
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The most likely diagnosis of the corneal findings based on clinical history and examination is lattice corneal dystrophy. However, these exact corneal findings may be seen in polymorphic amyloid degeneration, which is a degeneration (not dystrophy) of the corneal stroma that occurs later in life and does not affect visual acuity. Linear stromal lines are also seen in Avellino dystrophy, which is a combination of lattice and granular dystrophies. There are a few case reports in the literature of epithelial trauma from contact lens wear and trichiasis, as well as recurrent corneal erosion from anterior basement membrane dystrophy, resulting in lattice-like changes in the corneal stroma. In addition, prominent corneal nerves and ghost vessels may appear as lines in the stroma.
Clinical features
Lattice corneal dystrophy was first described in 1890 by Hugo Biber, a Swiss ophthalmologist. It is the most common of the corneal stromal dystrophies. It is typically bilateral, affects both men and women, and is characterized by an accumulation of amyloid in the cornea, white lines in the stroma and white dots in the central subepithelium. Patients may be asymptomatic for years before presenting with decreased vision or pain and photophobia from recurrent corneal erosions. The decline in visual acuity is secondary to the coalescence of lattice lines and white opacities, and the formation of stromal haze.
There are three subtypes of lattice corneal dystrophy.
Type 1 (Biber-Haab-Dimmer type) is the most common form. It is autosomal dominant in inheritance and mainly affects the central, anterior stroma of patients in their first or second decade of life. These patients typically experience decreased vision in their fourth decade that progressively worsens. Painful, recurrent corneal erosions are frequent.
Type 2 (Finnish or Meretoja type) is also autosomal dominant in inheritance. This form initially affects the peripheral stroma with progression to involve the visual axis. Typically, the onset of corneal findings is during the third decade and of symptoms is during the fifth decade of life. Corneal erosions are infrequent, and there is systemic amyloid involvement, including facial nerve palsy, peripheral neuropathy, skin changes and cardiac complications leading to heart failure.
Type 3 (Hida type) is autosomal recessive and characterized by thick, ropy lattice lines that extend from limbus to limbus in the mid stroma. These patients are typically older than those of types 1 and 2 and do not experience corneal erosions.
Type 3A is a variant of type 3 with identical thick, ropy lattice lines, but the inheritance is autosomal dominant and recurrent corneal erosions are common.
Histopathological examination of lattice corneal dystrophy reveals deposits of amyloid in the stroma. On hematoxylin and eosin (H&E) stain, these deposits are pink, amorphous, acellular and glassy in appearance (Figure 3). Staining with Congo red, these subepithelial and stromal amyloid deposits appear red (Figure 4) and manifest an apple-green birefringence when examined under polarized light.
Genetics
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Lattice corneal dystrophy is inherited in an autosomal dominant fashion, except for type 3.
The mutation is believed to be in the keratoepithelin or BIG-H3 gene on chromosome 5q31. This gene is involved in cell adhesion and blocking of epithelial proliferation. The specific mutations identified for each subtype is shown in the Table.
Management
Treatment includes measures for the recurrent corneal erosions, including lubricants, hypertonic saline, bandage contact lenses and patching. When advanced disease compromises visual acuity, phototherapeutic keratectomy and penetrating keratoplasty may be employed.
Our patient’s lattice corneal dystrophy was moderate and not yet visually significant. She had significant nuclear sclerotic, cortical and posterior subcapsular cataracts, right eye greater than left eye, which explained her visual complaints. She underwent cataract surgery in both eyes and is currently 20/20 in both eyes. We are closely following the progression of her lattice dystrophy.
For Your Information:
- My Hanh T. Nguyen, MD, and Helen Wu, MD, and can be reached at New England Eye Center, Tufts University School of Medicine, 750 Washington St., Box 450, Boston, MA 02111; 617-636-4219; fax: 617-636-4866; Web site: www.neec.com.
References:
- Edited by Jane Loman, MD, and Zinaria Williams, MD. Drs. Loman and Williams can be reached at New England Eye Center, Tufts University School of Medicine, 750 Washington St., Box 450, Boston, MA 02111; 617-636-4219; fax: 617-636-4866; Web site: www.neec.com. Drs. Loman and Williams have no direct financial interest in the products mentioned in this article, nor are they paid consultants for any companies mentioned.
- Aldave AJ, Lin DY, et al. Anterior basement membrane corneal dystrophy and pseudo-unilateral lattice corneal dystrophy in a patient with recurrent corneal erosions. Am J Ophthalmol. 2004;137(6):1124-1127.
- Aldave AJ, Principe AH, et al. Lattice dystrophy-like localized amyloidosis of the cornea secondary to trichiasis. Cornea. 2005;24(1):112-115.
- Chakravarthi SV, Kannabiran C, Sridhar MS, Vemuganti GK. TGFBI gene mutations causing lattice and granular corneal dystrophies in Indian patients. Invest Ophthalmol Vis Sci. 2005;46(1):121-125.
- Kanski JJ. Disorders of the cornea and sclera. In: Clinical Ophthalmology. 4th ed. Elsevier Science; 2002:124-134.
- Warren JF, Abbott RL, et al. A new mutation (Leu569Arg) within exon 13 of the TGFBI (BIGH3) gene causes lattice corneal dystrophy type I. Am J Ophthalmol. 2003;136(5):872-878.