Dystrophy, corneal

Dastgheib KA, Clinch TE, Manche EE, Hersh P, Ramsey J. Sloughing of corneal epithelium and wound healing complications associated with laser in situ keratomileusis in patients with epithelial basement membrane dystrophy. Am J Ophthalmol 130 297-303 (2000). 

In humans, mutations in the a2(VIII) gene result in corneal endothelial dystrophies, Fuchs endothelial dystrophy (FECD), and posterior polymorphous comeal dystrophy (PPCD). Recently, it was reported that the mutation L450W in COL8A2 causes an early-onset subtype of Fuchs corneal dystrophy. ... 

In the clinical study, perioperative complications were highlighted by two cases of early and unexplained emulsification, impairing fundus visualisation but not precluding reapplication. Post-operative complications were emulsification in seven case, including one very severe one. No corneal dystrophy and no ocular hypertonia were reported. 

One type of familial amyloidosis first identified in the Finnish population is caused by deposition of gelsolin (Maury et al., 2000 Maury et al., 2001). This Finnish type familial amyloidosis (FAF) is a hereditable autosomal dominant amyloid polyneuropathy, characterized by corneal lattice dystrophy, progressive cranial and peripheral neuropathy as well as skin changes (Chen et al., 2001 Maury et al., 2001). 

Topical application of glycerin in concentrations from 50% to 100% results in a significant reduction of corneal edema within 1 to 2 minutes. Because application to the eye is painful, a topical anesthetic must be instilled before use. It is useful in ophthalmoscopic and gonioscopic examination of the eye in acute angle-closure glaucoma, bullous keratopathy, and Fuchs endothelial dystrophy. 

New Classification System for Corneal Dystrophies Including Current Name, Alternate Name, Gene Affected, and Inheritance Pattern... 

Corneal dystrophy of Bowman s layer type 1 Reis-Biicklers TGBFI AD Comeal surface appears rough and irregular with accumulation of opacities at Bowman s layer in annular, crescent, polygonal, or map-like formations. Opacities are confined to central and mid-peripheral cornea, whereas the extreme periphery remains transparent. RCE common with surgery often required in second or third decades due to severe vision loss. 

Corneal dystrophy of Bowman s layer type 11 Thiel-Behnke TGFBI AD Characteristic superficial opacification in a honeycomb pattern. RCE common, though symptoms and opacification not as severe as in Bowman s type I. 

The following discussion focuses on the specific corneal dystrophies and degenerations that are most commonly encountered clinically. 

Fuchs (endothelial) dystrophy has a component of guttata, but the involvement is such that corneal physiology is affected adversely. Fuchs dystrophy occurs bilaterally, has been reported to be transmitted dominantly (with incomplete penetrance), and females are three times more likely to develop the condition. Prominent guttata initially occur centrally and then become extensive enough to involve the peripheral cornea. In Fuchs dystrophy the... 

Figure 26-8 Diagram of the deep lamellar endothelial keratoplasty procedure for patients with Fuchs corneal dystrophy and pseudophakic bullous keratopathy. (Diagram courtesy of Dr. Mark Terry of the Devers Eye Institute in Portland, Oregon.)...

Keratoconus is an ectatic corneal dystrophy that tends to be bilateral but may be asymmetric and generally manifests in the second or third decade of life. There is evidence that keratoconus is a hereditary condition, with a family history reported in 6% to 8% of patients with the disease.The prevalence in first-degree relatives is 15% to 67% higher than in the general population, and the incidence has been reported at approximately 1 in 2,000. The inheritance pattern has been variably reported as sporadic, autosomal recessive, and autosomal dominant. Keratoconus is likely a multigenic disease with a complex mode of inheritance, and its manifestation likely involves environmental factors. 

Although cataract surgery is a potential precursor to bullous keratopathy, there are many other causes. Fuchs endothelial dystrophy, infection, trauma, retained foreign body, posterior polymorphous dystrophy, chronic uveitis, chronically elevated intraocular pressure (lOP), and vitreous touch are all known causes of bullous keratopathy. Other less common causes of bullous keratopathy include corneal thermal injury secondary to carbon dioxide laser skin resurfacing, air bag trauma, the use of topical dorzolamide hydrochloride in glaucoma patients with endothelial compromise, and use of mitomycin C during trabeculectomy surgery. 

Patients with bullous keratopathy should have their lOP measured (even though corneal edema results in underestimated lOP) because angle-closure glaucoma can cause similar corneal edema. In addition, patients with Fuchs dystrophy have an increased risk of developing open-angle glaucoma in addition to the bullous keratopathy. Topical carbonic anhydrase inhibitors should be avoided in these patients because of the potential of worsening the corneal decompensation. 

Approximately 16% to 46% of RCEs are associated with ABMD. Other corneal dystrophies associated with RCE include Fuchs , Reis-Biicklers, lattice, and granular. Dystrophic RCEs are typically bilateral and less severe. 

Rosenberg ME, Tervo TM, PetroU WM, Vesaluoma MH. In vivo confocal microscopy of patients with corneal recurrent erosion syndrome or epitheUal basement membrane dystrophy. Ophthalmology 2000 107 565-573. 

Sridhar MS, Rapuano CJ, Cosar CB, et al. Phototherapeutic keratectomy versus diamond burr polishing of Bowman s membrane in the treatment of recurrent corneal erosions associated with anterior basement membrane dystrophy. Ophthalmology 2002 109 674-679. 

Vincent, AL, Rootman D, Munier FL, Heon E. A molecular perspective on corneal dystrophies. Dev Ophthalmol 2003 37 50-66. 

Serious Side Effects. Corneal decompensation in patients with preexisting endothelial compromise (e.g., Fuchs endothelial dystrophy) and hypotony have been reported with topical CAIs. Common adverse reactions to oral CAIs are summarized in Box 34-6. 

Phosphatidylinositol 3,5-bisphosphate (PI-3,5-P2, 6) is the low abundance, newest member of PIPn family (33). It is involved in mediation of several cellular processes such as vacuolar homeostasis, membrane trafficking, and vesicular protein sorting (36, 38). The recently discovered PI-3,5-P2 effectors include a family of -propeller, epsin, and CHMP protein families (39). The importance of PI-3,5-P2 in human physiology is demonstrated by its role in insulin signaling, myotubular myopathy, and corneal dystrophy (38). 

Hereditary lattice corneal dystrophy Mainly C-terminal fragments of kerato-epithelin Systemic... 

C-GlcNAc6ST Human 1 Macular corneal dystrophy type 1, II Loss of vision 50... 

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