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Ophthalmology > CORNEA
Keratopathy, Band
Article Last Updated: Feb 15, 2006
AUTHOR AND EDITOR INFORMATION
Section 1 of 10  
Author: Michael Taravella, MD, Director of Cornea and Refractive Surgery, Rocky Mountain Lions Eye Institute; Associate Professor, Department of Ophthalmology, University of Colorado School of Medicine
Michael Taravella is a member of the following medical societies: American Academy of Ophthalmology, American Medical Association, American Society of Cataract and Refractive Surgery, Association for Research in Vision and Ophthalmology, Contact Lens Association of Ophthalmologists, and Eye Bank Association of America
Editors: Stephen D Plager, MD, FACS, Chief, Department of Ophthalmology, Dominican Hospital; Assistant Clinical Professor, Department of Ophthalmology, Stanford University Hospital; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Christopher J Rapuano, MD, Professor, Department of Ophthalmology, Jefferson Medical College; Co-Chairman of the Cornea Service, Co-Chairman of Refractive Surgery Department, Wills Eye Hospital; Lance L Brown, OD, MD, Ophthalmologist, Affiliated With Freeman Hospital and St John's Hospital, Regional Eye Center, Joplin, Missouri; Hampton Roy Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences
Author and Editor Disclosure
Synonyms and related keywords:
band keratopathy, calcific band keratopathy, corneal degeneration, calcium deposition, cornea
Background
Band keratopathy derives its name from the distinctive appearance of calcium deposition in a band across the central cornea. This corneal degeneration can occur from a variety of causes, both systemic and local.
Pathophysiology
Band keratopathy is the result of precipitation of calcium salts on the corneal surface (directly under the epithelium). Serum and normal body fluids (eg, tears, aqueous humor) contain calcium and phosphate in concentrations that approach their solubility product. Evaporation of tears tends to concentrate solutes and to increase the tonicity of tears; it is especially true in the intrapalpebral area where the greatest exposure of the corneal surface to ambient air occurs. Elevated serum calcium or serum phosphate can tip the balance in favor of precipitation. Topical medications that contain phosphates also may contribute to this problem. Finally, elevation of the surface pH out of the physiologic range changes the solubility product and favors precipitation. This type of tissue pH change can be seen in chronically inflamed eyes and may explain, in part, why patients with uveitis are at risk for the development of this problem.
Endothelial function may play a role in the formation of calcium deposition. Compromise of endothelial function and corneal edema are sometimes seen in patients who have silicone oil inside the eye when it comes into contact with the posterior cornea. Although this association has been noted, the exact reasons remain uncertain.
Frequency
United States
Exact incidence of calcific band keratopathy is unknown.
Mortality/Morbidity
Patients with band keratopathy may experience a decrease in vision as the deposition progresses across the visual axis. A foreign body sensation and irritation associated with an irregular surface are common symptoms. The ocular discomfort may worsen to the point of becoming disabling. The plaque itself often is visible and of cosmetic concern to the patient and family members.
Sex
No known difference exists in the incidence of band keratopathy between men and women.
Age
No known association of band keratopathy exists with increasing age.
History
- Patients with band keratopathy complain of the following:
- Decreased vision
- Foreign body sensation
- Ocular irritation
- Redness (occasionally)
Physical
Visual acuity will be decreased in proportion with the density of deposition of calcium salts in the central cornea. Slit lamp examination often reveals a whitish-grayish plaquelike deposition that occurs in a band across the cornea. The very periphery of the cornea may be spared because of the buffering effect of limbal blood vessels. Holes in the plaque may be apparent; these holes represent spaces where the corneal nerves are traversing the Bowman membrane to the epithelial surface.
- The calcium deposition typically begins in the periphery and progresses centrally but, occasionally, may begin centrally.
- The calcium may be very fine or thick and plaquelike. When it is thick, it may flake off, causing epithelial defects and painful symptoms.
Causes
- The following systemic conditions are associated with band keratopathy:
- Hypercalcemia due to the following:
- Hyperparathyroidism
- Excessive vitamin D intake
- Renal failure
- Hypophosphatasia
- Milk-alkali syndrome
- Paget disease
- Sarcoidosis
- Other systemic conditions
- Discoid lupus erythematosus
- Tuberous sclerosis
- Local ocular conditions
- Chronic uveitis
- Juvenile rheumatoid arthritis with uveitis
- Phthisis bulbi
- End stage glaucoma
- Anterior mosaic dystrophy
- Drug-associated calcium deposition
- Steroid phosphate preparations
- Pilocarpine containing mercurial based preservatives
- Viscoelastic agents (rare, early formulations; may be related to phosphate buffers)
- Silicone oil
- Chemical fume related
- Mercury vapor
- Calcium bichromate vapor
- Intraocular use of recombinant tissue-plasminogen activator (rt-PA)
Keratitis, Interstitial
Other Problems to be Considered
Primary and secondary calcareous degeneration of the cornea
Calciphylaxis (an ocular and systemic hypersensitivity response characterized by calcium deposition in response to specific antigens or agents)
Gout (urate crystal deposition may occur in a band pattern)
Spheroidal degeneration (bandlike deposition of hyaline)
Lab Studies
- Patients who present with band keratopathy should have a serum calcium and phosphate level drawn unless the deposition has been documented previously and a known underlying cause exists.
- If sarcoid is suspected, an angiotensin-converting enzyme (ACE) should be obtained.
- Parathyroid hormone levels should be checked in otherwise idiopathic cases.
Histologic Findings
Band keratopathy is characterized by calcium deposition involving the Bowman layer and the superficial stroma of the cornea. The earliest changes include basophilic staining of the Bowman layer. Amorphous eosinophilic connective tissue and a fibrous pannus often are present between the calcium deposition and the overlying epithelium in more advanced cases. Calcium is deposited intracellularly when hypercalcemia is the cause; extracellular deposits are characteristic of local ocular disease.
Medical Care
Medical therapy is ineffective in treating this condition. However, underlying conditions associated with elevated calcium or phosphate should be treated to prevent deposition from recurring (eg, patients on dialysis who subsequently undergo renal transplantation often have a more normal phosphate level).
Surgical Care
Surgical debridement of band keratopathy is usually effective in restoring normal vision.
- The procedure can be performed in a minor operating room under topical anesthesia. Proparacaine or tetracaine drops can be used for this purpose. Use of an operating microscope is recommended.
- Place a lid speculum to hold open the eyelids.
- Debride the epithelium overlying the calcium with an ophthalmic surgical blade or spatula.
- Apply 0.05 mol, 1.5% neutral disodium ethylenediaminetetraacetic acid (EDTA) to the corneal surface. Weck-cel sponges soaked in this solution can be used for this purpose. Alternatively, the solution can be placed in a water bath over the cornea to limit ocular exposure.
- Then, remove calcium deposits with firm scraping of the corneal surface with a blunt spatula. (A Paton spatula works well.) Often, it is necessary to apply solution, followed by scraping several times to remove the plaque. The primary goal is to clear the visual axis. Thin calcium deposits may come off in 5 minutes, while thick plaques may take 30-45 minutes to dissolve.
- Once this has been accomplished, an assessment of the smoothness of the underlying stroma can be made. If the surface is very irregular, phototherapeutic keratectomy with an excimer laser can be performed to smooth the surface. Ideally, this procedure is performed in the same setting. Note that the excimer laser should not be used to remove calcium. Attempting to remove band keratopathy with the excimer laser alone will result in significant irregular astigmatism since the cornea, not calcium, will be ablated preferentially. The role of the excimer is to polish the surface after the plaque has been removed.
- Irrigate the eye thoroughly following the procedure to remove EDTA solution from the conjunctival surface and fornices.
- Place a bandage contact lens over the cornea. Alternatively, pressure patching or frequent antibiotic ointment can be used.
- Postoperative care includes the insertion of a bandage contact lens that is left in place until the epithelium heals. Topical nonsteroidal agents are useful for pain control immediately following the procedure and for the first few days afterwards. An antibiotic drop should be prescribed with the bandage lens in place. Use of a topical steroid drop (eg, prednisolone acetate [not phosphate]) is helpful for comfort and treatment of the inflammation and corneal edema that often is present in the early postprocedure period. These medications can be stopped when the epithelium is healed, and the bandage lens is removed (usually within the first 1-2 wk).
- Occasionally, mild subepithelial haze can be seen weeks after EDTA chelation. This may resolve on its own. A mild topical steroid (eg, fluorometholone 0.1%) may help to resolve this haze. If there is significant damage to the Bowman membrane, the haze may be permanent.
Diet
As noted, excessive vitamin D intake has been associated with band keratopathy, as has milk-alkali syndrome. Excessive absorption and serum elevation of calcium is the consequence of these 2 diet-related problems.
Further Outpatient Care
- Patients should receive follow-up care as needed.
Complications
- The main complications related to removal of calcium deposits on the corneal surface include the following:
- Pain
- Recurrence of the band
- Corneal scarring
- Corneal edema
- Infection
- Incidence of adverse outcomes following this superficial debridement is very low.
Prognosis
- Unless underlying conditions have been addressed, removing the calcium deposits will be associated with a high incidence of recurrence. However, in general, superficial debridement restores vision and comfort for most patients with this condition.
Medical/Legal Pitfalls
- As with all surgical procedures, informed consent should be obtained prior to removal of calcium plaques or band keratopathy. Specific risks should include loss or decrease of vision, corneal scarring, pain, infection, and need for further procedures.
| Media file 1:
Band keratopathy. Note the bandlike whitish-grey lesion across the corneal surface, sparing the superior and inferior cornea. |
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| Media file 2:
Calcium deposition associated with the use of dexamethasone phosphate. The calcium plaques appear as elevated white lesions at the edge of a persistent epithelial defect. |
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| Media file 3:
Total calcification of the cornea. Deep and superficial layers of the cornea are involved with this process. |
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| Media file 4:
The image shown is of a patient who developed a calcium plaque following a corneal transplant and the use of a topical steroid phosphate preparation. |
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Keratopathy, Band excerpt Article Last Updated: Feb 15, 2006
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