Premium Wordpress Themes by UFO Themes
ANTERIOR CORNEAL DYSTROPHIES
EPITHELIAL BASEMENT MEMBRANE DYSTROPHY (ANTERIOR BASEMENT MEMBRANE DYSTROPHY, MAP-DOT-FINGERPRINT DYSTROPHY, AND COGAN MICROCYSTIC DYSTROPHY)
Epithelial basement membrane (EBM) dystrophy is a common epithelial dystrophy that can cause painful recurrent corneal erosions and/or decreased vision.
Etiology and Pathology
• EBM dystrophy is caused by an abnormality of production of EBM that extends into the epithelium, leading to multiple basement membrane layers in the corneal epithelium. Trapped epithelial cells can form “Cogan microcysts.”
• Typically degenerative, occasionally autosomal dominant (transforming growth factor beta-induced [TGFBI] gene of chromosome 5q31)
• Most commonly asymptomatic
• Recurrent erosion syndrome: may have unilateral or bilateral recurrent episodes of pain in the middle of the night or upon opening the eyes after sleep. Can occur after trauma with a sharp object, such as a fingernail, tree branch, or paper edge.
• May note painless distortion of vision, including monocular “shadow” vision or multiple images, when the central cornea is involved
• Slit-lamp examination shows map-like lines, dots (microcysts), and/or fingerprint-like epithelial lesions, which may occur singly or in various combinations (Fig. 5-1, eFig. 5-1A-J). These findings are best seen with retroillumination and with a broad slit beam from the side. “Negative staining” from slightly elevated areas of epithelium may be seen with fluorescein dye.
• Eyes with recurrent erosions may have minimal clinical findings, localized areas of loose epithelium, or a frank epithelial defect.
• Other anterior corneal dystrophies, such as Meesmann dystrophy and Reis-Bücklers and Thiel-Behnke dystrophies
• If vision is decreased owing to central involvement, the irregular epithelium can be debrided, with or without a diamond burr polishing or excimer laser phototherapeutic keratectomy (PTK).
• Painful erosions can be treated with lubrication, hypertonic drops and ointment (sodium chloride 5%), pressure patching, topical corticosteroids and oral doxycycline, bandage soft contact lens, epithelial debridement, anterior stromal micropuncture, diamond burr polishing of Bowman membrane, or excimer laser PTK.
• Very good with appropriate treatment, although some patients have recalcitrant recurrent erosions.
FIGURE 5-1. (continued) C. Map-like changes in this eye are almost confluent centrally, resulting in significant visual distortion. D. The map-like changes here are often referred to as a “mare’s tail” pattern.
FIGURE 5-1. (continued) G. A large area of epithelial microcysts is seen superiorly. H. Retroillumination view of the same eye seen in G highlights the epithelial microcysts.
MEESMANN CORNEAL DYSTROPHY (JUVENILE HEREDITARY EPITHELIAL DYSTROPHY)
Meesmann dystrophy is a rare bilateral epithelial disorder that can cause ocular irritation and photophobia.
Etiology and Pathology
• Meesmann dystrophy is an autosomal dominant (keratin K3 and keratin K12 genes of chromosomes 12q13 and 17q12, respectively) condition in which hundreds of tiny vesicles containing periodic acid-Schiff (PAS)-positive “peculiar substance” are found in the epithelium.
• Patients are usually asymptomatic but may note irritation, glare, and photophobia. Mild pain may develop in adulthood as a result of recurring corneal erosions.
• Most patients require no treatment. Consider lubrication and sunglasses for mild symptoms. Rarely, a bandage soft contact lens can be used or a superficial keratectomy can be performed for severe symptoms, but the dystrophy will recur.
• Good, although some patients will have chronic symptoms.
LISCH CORNEAL DYSTROPHY
Lisch corneal dystrophy is a rare, typically bilateral, epithelial disorder that can cause decreased vision if the visual axis is involved.
Etiology and Pathology
• Lisch corneal dystrophy is an X-linked dominant condition (chromosome Xp22.3) in which PAS-positive vacuolated cells are found in the epithelium.
• Patients are usually asymptomatic but may note some decreased vision if the abnormal cells are centrally located.
• Most patients require no treatment. Consider lubrication and sunglasses for mild symptoms. Rarely, a superficial keratectomy can be performed for severe symptoms, but the dystrophy will recur.
• Good, although rare patients will have chronic symptoms.
REIS-BÜCKLERS AND THIEL-BEHNKE DYSTROPHIES
Reis-Bücklers (corneal dystrophy of Bowman layer, type I-CDB 1) and Thiel-Behnke (corneal dystrophy of Bowman layer, type II-CDB 2) dystrophies are uncommon, bilateral, symmetric, very similar dystrophies of Bowman membrane that cause pain and decreased vision early in life.
Reis-Bücklers and Thiel-Behnke dystrophies are autosomal dominant (TGFBI gene of chromosome 5q31) disorders that cause damage and scarring to Bowman membrane and the anterior stroma.
• Severe recurrent corneal erosions from a young age, even soon after birth; may be somewhat more severe for Reis-Bücklers dystrophy than Thiel-Behnke dystrophy.
• Progression of the condition leads to reduced vision that occurs in the second to third decades of life, although in severe cases, it can occur in the first decade.
• Honeycomb appearance because of reticular, ring-shaped, subepithelial opacities that are most dense centrally but may involve the entire cornea. With time, they can progress deeper into the stroma (Fig. 5-4A-G, eFig. 5-4A and B).
• Although difficult to distinguish clinically, Reis-Bücklers displays more irregular diffuse opacities with clear interruptions, whereas Thiel-Behnke exhibits multiple flecks with reticular formation.
• On electron microscopy, Reis-Bücklers demonstrates subepithelial electron-dense, rod- or trapezoidal-shaped bodies, as opposed to Thiel-Behnke, which demonstrates curly fibers.
• Other anterior or stromal dystrophies (e.g., EBM dystrophy, granular dystrophy, macular dystrophy)
• Mild cases: lubrication
• More severe cases: bandage soft contact lenses, superficial keratectomy, excimer laser PTK, midstromal or deep anterior lamellar keratoplasty, or penetrating keratoplasty may be necessary.
• Excimer laser PTK can be quite successful in improving vision and decreasing painful episodes in many cases. Keratoplasty may be required in advanced cases. Recurrence in the donor graft is common after corneal transplantation and also after PTK (Fig. 5-4H and I, eFig. 5-4H and I). Excimer laser PTK can often be repeated or performed for recurrence after keratoplasty.
GELATINOUS DROP-LIKE CORNEAL DYSTROPHY
Gelatinous drop-like corneal dystrophy is a rare condition that causes significant symptoms early in life.
Etiology and Pathology
• Gelatinous drop-like corneal dystrophy is an autosomal recessive condition (tumor-associated calcium signal transducer 2 gene of chromosome 1p32).
• Histopathology: subepithelial and stromal amyloid deposits
• Severe decreased vision, pain, redness, photophobia, and tearing beginning in the first two decades of life
• There are a variety of presentations, including relatively flat subepithelial opacities similar to band keratopathy, small or large groups of elevated nodules (“mulberry” pattern) (Fig. 5-5A), and larger nodular lesions (“kumquat” pattern).
• Superficial and deep neovascularization may develop.
• Superficial and deep stromal opacification may also develop.
• Other anterior or stromal dystrophies (e.g., macular dystrophy, Reis-Bücklers dystrophy, granular dystrophy)
WordPress theme by UFO themes