Adenovirus Punctate epithelial keratitis is most often seen after adenoviral infection and is due to subepithelial immune complex deposition.

Noninfectious causes

Punctate epithelial erosions are most commonly seen in patients with lagophthalmos or dry eye disease. Peripheral (marginal) keratitis is usually associated with blepharokeratoconjunctivitis secondary to meibomian gland disease.

Thygeson superficial punctate keratitis The etiology of this condition is unclear, but it is thought to be immune mediated. It can occur in children and presents with tearing, photophobia, and reduced vision. It is bilateral but often asymmetric. Characteristic features include slightly elevated gray corneal epithelial lesions that do not stain. It is treated with mild steroids (eg, fluorometholone 0.1%) or topical cyclosporine 0.05%.

Cogan syndrome Cogan syndrome is a rare vasculitis that presents with ocular, audiovestibular, and systemic features. Interstitial keratitis, uveitis, conjunctivitis, episcleritis, or a combination of these features may be seen.

Systemic Diseases Affecting the Cornea or Iris

Metabolic Disorders Affecting the Cornea or Iris

See the section Inborn Errors of Metabolism in Chapter 28 for additional discussion of some of the disorders covered here.

Mucopolysaccharidosis

Corneal haze may be present in early life in 3 lysosomal disorders: by age 6 months in mucopolysaccharidosis I H (Hurler syndrome); by age 12–24 months in mucopolysaccharidosis I S (Scheie syndrome); and as early as age 6 weeks in mucopolysaccharidosis IV (Morquio syndrome). Treatment options for significant opacities include penetrating keratoplasty and DALK.

Cystinosis

Cystinosis is a rare metabolic disease characterized by elevated levels of cystine within the cell. Cystine crystals are deposited in various places throughout the body. The major presenting symptoms of the infantile form of cystinosis are failure to thrive, rickets, and progressive renal failure, collectively resulting in Fanconi syndrome. The ocular findings of cystinosis are pathognomonic. Iridescent elongated corneal crystals appear at approximately age 1 year, first in the peripheral part of the cornea and the anterior part of the stroma (Fig 20-14). Severe photophobia can make slit-lamp examination difficult. These crystals are also present in the uvea and on the surface of the iris. As survival has improved, reports of angle-closure glaucoma secondary to crystal deposition in the ciliary body have increased. Oral cysteamine has been shown to alleviate the systemic problems but not the corneal crystal deposition. Topical cysteamine can reduce crystal deposition in the cornea. However, the medication may be difficult to obtain and has an unpleasant odor, and treatment is complicated by the need for frequent application.

Figure 20-14 Cystinosis with corneal involvement. (Courtesy of Gregg T. Lueder, MD.)

Tyrosinemia

Children with tyrosinemia often present with photophobia, pseudodendritic ulcers on the cornea, and ulceration on the palms and soles. Systemic problems include liver and kidney dysfunction.

Hepatolenticular degeneration

Hepatolenticular degeneration (Wilson disease), an autosomal recessive inborn error of metabolism, results in excess copper deposition in the liver, kidneys, and basal ganglia of the brain, leading to cirrhosis, renal tubular damage, and a Parkinson-like disorder of motor function. The characteristic copper-colored Kayser-Fleischer ring is limited to Descemet membrane and can be several millimeters in width. It may resolve with treatment. Because this ring can develop fairly late, laboratory tests for serum copper and ceruloplasmin are better than an eye examination for early diagnosis.

Fabry disease

Fabry disease is a rare X-linked lysosomal storage disease due to α-galactosidase deficiency. Vortex keratopathy (verticillata) can be seen in affected males and in female carriers.

Schnyder crystalline dystrophy

Schnyder crystalline dystrophy is caused by mutations in the UBIAD1 gene and is thought to be a local disorder of corneal lipid metabolism.

Other Systemic Diseases Affecting the Cornea or Iris