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Web Exclusive: A Look at Lattice Corneal Dystrophy

An overview of its diagnosis and management
 
by Steve Lenier, contributing editor
 
            Recently, a patient of Dr. Danielle Trief brought his daughter to see her as a new patient. The daughter’s chief complaint: some light sensitivity and a little ocular irritation. The patient’s father has a history of PK for lattice corneal dystrophy.      
            “I examined her at the slit lamp, and I could see a very subtle retractile branching lesion in her anterior stroma,” Dr. Trief, assistant professor of ophthalmology at Columbia University Medical Center, explains. “Given her father’s history and the fact that this is an autosomal dominant condition, I had a high suspicion that this patient would develop lattice dystrophy.” 
            Lattice corneal dystrophy (LCD) is one of several types of dystrophies of the cornea. It is in the category of stromal dystrophies, meaning it affects the stromal layer of the cornea. 
            Here, Drs. Trief and Robert S. Feder, MD, professor of ophthalmology and chief of the Cornea Service at the Feinberg School of Medicine, Northwestern University, discuss the diagnosis and management of lattice dystrophy to facilitate the care of these patients.
 
Diagnosis
            The symptoms of LCD are a continuous and progressive loss of vision and ocular irritation, which can appear in the first decade of life and inflict vision issues between the fourth and sixth decade of life. 
Clinically, the patient often presents with recurrent epithelial erosions. Of note:  
The erosions can appear at the slit lamp, before amyloid deposits in the stroma and cloud the cornea, leading to vision impairment. The amyloid deposits form as delicate, branching structures that create a lattice pattern. Although LCD is usually bilateral, it may not be symmetrical, and may occur unilaterally.
            Dr. Feder says that when LCD occurs in children, it appears as subtle lines, dots, or haze rather than lattice lines. These same findings can be seen after keratoplasty.
            “The haze might first be thought to be a graft rejection, but it will not clear with use of a topical steroid,” he explains.  
            Dr. Trief notes that family history is significant for the LCD diagnosis.
            “It’s an autosomal dominant condition, so most of my patients that have it have a family history of lattice dystrophy. I think if you were just examining someone without the family history, you might not make much of it; you might think it’s an old corneal scar.”
 
         The symptoms of LCD are a continuous and progressive loss of vision and ocular irritation, which can appear in the first decade of life and inflict vision issues between the fourth and sixth decade of life. 
 
            Some other information to consider:
            LCD is classified by the International Classification of Corneal Dystrophies (IC3D) as an Epithelial-Stromal TGFBI dystrophy. Reis Bucklers, Thiel-Behnke and granular dystrophy are also in this category. These dystrophies all share a common gene, transforming growth factor beta-induced, Dr. Feder explains. 
            Dr. Trief points out that LCD can be mistaken for Ehlers-Danlos syndrome, as a result of the skin laxity seen in both conditions, and its symptoms of ocular dryness can make an ophthalmologist mistake it for Sjögren’s syndrome. Systemic amyloidosis can manifest in the cornea with findings similar to LCD, but the lesions are typically heavier in the corneal periphery, and follow the corneal nerves, Dr. Feder points out. Additionally, the condition can be confused with polymorphic amyloid degeneration (PAD). 
            “This degeneration occurs in older people. It is usually bilateral like LCD, and the crystalline opacities are confined to the central and paracentral cornea,” explains Dr. Feder. “In contrast to LCD, the crystals are noted to be deep in the stroma and may even indent Descemet membrane without causing corneal edema. The crystals in PAD are typically shorter than in LCD and may even appear punctate.”
            He notes that PAD is not associated with corneal erosions, and visual compromise with PAD is not typical.
 
Management
            Dr. Trief says her initial approach is to follow these patients. Specifically, roughly every 6 months if it’s subtle, and more frequently for patients who have advanced disease or who underwent a PK.  
            “LCD could go on for many years before requiring intervention, and some patients won’t need an intervention if it’s more on the mild side,” she explains.
            Should she note corneal erosion, she says she’ll intervene:
            “A lot of times in lattice dystrophy we’re treating corneal erosion with lubrication — sometimes sodium chloride ointment helps reduce the incidence of erosions, and a bandage contact lens can help as well,” she says. “Recently, I’ve had success with specialty contact lenses, such as scleral lenses, as they vault over the cornea, so the cornea stays in a fluid pocket, which can help with lubrication and, thus, help with vision because it aids in eliminating some of the irregular astigmatism when the contact lens is on. It also provides a barrier, so that you don’t still have this erosion.”
 
“LCD could go on for many years before requiring intervention, and some patients won’t need an intervention if it’s more on the mild side.” – Danielle Trief, MD
 
            For more serious cases, in which a lot of deposits are seen, surgical intervention may be  required, says Dr. Trief. This can be either be a PK, replacing the whole cornea in the traditional way, or a deep anterior lamellar keratoplasty (DALK), where the patient’s endothelium is retained. This is effective because LCD affects the stroma, but it doesn’t affect the corneal endothelium. Dr. Trief adds that LCD frequently recurs following transplant, with variable times to recurrence.
            Prior to considering keratoplasty, some clinicians prefer to try PTK with the excimer laser. This is reasonable if the pathology does not exceed 100 μm, as measured with anterior segment OCT. Typically, a topical masking agent, such as methylcellulose, is used for best results. Some clinicians feel that the laser increases amyloid deposition, and it should not be used for correcting refractive error. The patient should be warned that there might be significant change in refractive error. A diamond burr can be used to smooth the cornea; however, this technique may result in irregular astigmatism.  
 
That Patient
            Because the patient mentioned above has good vision and her symptoms are mild, Dr. Trief says she continues to monitor her. CP