Labrador keratopathy

Labrador keratopathy: Description, Causes and Risk Factors:A bilateral, symmetrical corneal dystrophy caused by prolonged exposure to extremes of heat or cold; nodular opacities are limited to the interpalpebral area and vision is only mildly affected.Labrador keratopathyLabrador keratopathy (LK) is an acquired disease in people who have spent most of their lives outdoors exposed to ultraviolet irradiation. There is an almost unanimous opinion among the authors that climatic conditions and aging are the main factors of this acquired corneal degeneration. The theory is that UV exposure results in altered proteins depositing at the limbus. The proteins contain a high content of sulfur.Stages:Stage 1. Small oil-like droplets are seen in the corneal epithelium, beginning at the limbus in the interpalpebral area. The central corneal epithelium is not yet involved. Vision is not yet impaired. This stage is difficult to demonstrate photographically.
  • Stage 2. This is characterised by the spreading of these droplets across the cornea to involve the epithelium of the central area and the lower half of the cornea. Vision is 6/12 or less. In some cases there is pigment migration from the conjunctiva on to the cornea in the interpalpebral area.
  • Stage 3. This is characterised by an increase in the size of the droplets, which begin to invade the deeper part of the epithelium and the superficial parts of the stroma. These droplets now form yellow nodules which protrude above the surface of the epithelium. Vision is 6/24 or less.
  • Stage 4. In this stage the nodular swellings erode through the epithelium, causing deep ulcers involving epithelium and stroma. Corneal sensation is diminished or absent in the involved area and vision is severely impaired (6/60 or less). The lesions remain painless and the cornea is not vascularized.
  • Stage 5. The corneal lesions become denser and deeper and the involved cornea shows vascularization which is a result of recurrent secondary infections. Vision is less than 1/60.
Typically, the lesions are associated with high UV exposure climates and/or reflected light such as observed in desert, ocean and snow. The incidence rises with age. Prevalence is 7% in areas of South Africa. The prevalence is higher in Greenland than Copenhagen.Seventeen black patients with Labrador keratopathy and mature cataracts underwent extracapsular cataract extraction. The severity of the Labrador keratopathy was recorded photographically pre-and post-operatively. The follow-up ranged from 6 to fifteen months. A 92% showed regression of the LK. The reduction in exposure to ultraviolet light as a result of aphakic photophobia could be one of the factors which have led to the regression of the Labrador keratopathy.Symptoms:Photophobia. Diagnosis:The diagnosis is based on Histopathology, amorphous mauve colored globules are seen in the superficial corneal stroma or substantia propria close to the limbus in hematoxylin and eosin stain (H&E stain). The globules are often confluent. The globules are not dissolved by elastase. It is very easy to confuse these globules with calcification especially when they are in the cornea near Bowman's layer. However, careful examination shows that they lack the granular quality and deep purple color of calcium crystals but rather are amorphous centrally homogeneous deposits. The globules may stain focally and usually peripherally with Congo red. This may lead to misconclusions that the deposits are amyloid but there is no dichroism with polarized light.Treatment:Sunglasses and artificial tears are suggested for lesser degree of Labrador keratopathy, and for advanced cases superficial keratectomy and lamellar corneal grafts may be indicated.Superficial keratectomy is usually done under topical anesthesia (drops or ointments that numb the eye) and usually no shots or injections are needed nor is it done under general anesthesia. A special knife is inserted partially through the cornea and a dissection carried out to remove the growth. This leaves a raw spot on the cornea and a bandage contact lens is generally worn for 7-10 days while the tissue heals. Pain varies but usually is not severe and relived with medication.NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.


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