Keratitis is the generic name given to any kind of inflammation of the cornea, the dome shaped translucent membrane at the front of the eye that both covers and protects the eye as well as being part of the focussing function.
The cornea is made up of five individual layers which can all be subject to a variety of inflammations. In the case of Thygeson’s disease it’s the front layer – the epithelial layer – that is subject to the keratitis.
Phillips Thygeson first brought the disease to the attention of ophthalmologists in 1950 from work on his case studies. He defined it as a keratitis where the bouts of inflammation come and go and identified small lesions (punctures, cuts or grazes) on the surface made up of lots of tiny grey coloured dots, together giving a slightly cloudy appearance.
The disease now has been given the official medical name of “Thysgeson’s Superficial Punctate Keratitis” or TSPK.
Although bouts last from several days to a few weeks, returning again within weeks or months, the disease is chronic in that it can last for anything upwards of thirty years. In between bouts the eyes are fortunately normal.
What are the symptoms?
Symptoms are consistent with those for any keratitis:
• Dry and excessively watering eyes at varied times
• Sensitivity to light and glare
• Blurred vision
• The feeling of dirt or grit being in the eye
These symptoms in themselves cannot diagnose TSPK and a slit lamp test is required to provide confirmation by presence of the lesions and minute punctures. Whilst the lesions can cover the whole cornea, generally they seem to be concentrated around the central area.
Who gets it?
The disease is not infectious and quite rare; there is no information on whether or not gender, race or geographic location has any anything to do with it.
Causes of the disease are also somewhat vague, with various viral agents being considered, including the herpes simplex virus, but research is not conclusive.
It’s thought that TSPK might be associated with a variety of actions and conditions:
• Injuries due to arc welding overuse of lamps
• Exposure to chemicals
• Reactions to drugs prescribed for unrelated disorders
• Immune or allergic reaction
Eye drops used to act as artificial tears help lubricate the eye and prevent any bumps on the epithelial surface from causing pain and discomfort
Both antiviral and antibiotic medications have proven to be of little use.
Corticosteroids are often prescribed, but careful management of those drugs needs to be carried out in case they prolong the overall chronic nature of the disease. The fact that some immediate relief is obtained from corticosteroid use is indicative that an auto-immune deficiency of some kind is at work.
Soft contact lenses have been found to provide long term relief by comforting the punctures during blinking, but care and discipline with hygiene is essential, otherwise an alternative keratitis – microbial keratitis – may develop.
Refractive and laser surgery has been used to alleviate symptoms but there is little information available on success or otherwise.