Others likely also exist.Patients with a parent, sibling, or child who has keratoconus have 15 to 67 times higher risk in developing corneal ectasia compared to patients with no affected relatives. Pathophysiology
Despite considerable research, the cause of keratoconus remains unclear. Several sources suggest that keratoconus likely arises from a number of different factors: genetic, environmental or cellular, any of which may form the trigger for the onset of the disease. Once initiated, the disease normally develops by progressive dissolution of Bowmans layer, which lies between the corneal epithelium and stroma. As the two come into contact, cellular and structural changes in the cornea adversely affect its integrity and lead to the bulging and scarring characteristic of the disorder. Within any individual keratoconic cornea, regions of degenerative thinning coexisting with regions undergoing wound healing may be found. Scarring appears to be an aspect of the corneal degradation; however, a recent, large, multicenter study suggests abrasion by contact lenses may increase the likelihood of this finding by a factor over two.A number of studies have indicated keratoconic corneas show signs of increased activity by proteases, a class of enzymes that break some of the collagen cross-linkages in the stroma, with a simultaneous reduced expression of protease inhibitors. Other studies have suggested that reduced activity by the enzyme aldehyde dehydrogenase may be responsible for a build-up of free radicals and oxidising species in the cornea. Whatever the pathogenetical process, the damage caused by activity within the cornea likely results in a reduction in its thickness and biomechanical strength.
This impingement can cause pain in both upper and lower limbs and a numbness or tingling sensations in the hands and feet because the nerves are supplying sensation to their dermatomes.Osteophytes on the fingers or toes are known as Heberdens nodes (if on the distal interphalangeal joint) or Bouchards nodes (if on the proximal interphalangeal joints). Treatments
Normally, asymptomatic cases are not treated. Non-steroidal anti inflammatory drugs and surgery are two typical options for cases requiring treatment. References
External links

Mayo Clinic website concise information on bone spurs