Radial keratotomy
Radial keratotomy is a refractive surgery procedure where the surgeon makes a spoke-like pattern of incisions into the cornea to modify its shape. This early surgical option for myopia has been largely superseded by LASIK and other similar procedures. LASIK is absolutely contraindicated in keratoconus and other corneal thinning conditions as removal of corneal stromal tissue will further damage an already thin and weak cornea. For similar reasons, radial keratotomy has also generally not been used for people with keratoconus. Prognosis
Patients with keratoconus typically present initially with mild astigmatism and myopia, commonly at the onset of puberty, and are diagnosed by the late teenage years or early 20s. The disease can, however, present or progress at any age; in rare cases, keratoconus can present in children or not until later adulthood. A diagnosis of the disease at an early age may indicate a greater risk of severity in later life. Patients vision will seem to fluctuate over a period of months, driving them to change lens prescriptions frequently, but as the condition worsens, contact lenses are required in the majority of cases. The course of the disorder can be quite variable, with some patients remaining stable for years or indefinitely, while others progress rapidly or experience occasional exacerbations over a long and otherwise steady course. Most commonly, keratoconus progresses for a period of 10 to 20 years before the course of the disease generally ceases in the third and fourth decades of life.
The topographical map indicates any distortions or scarring in the cornea, with keratoconus revealed by a characteristic steepening of curvature that is usually below the centerline of the eye. The technique can record a snapshot of the degree and extent of the deformation as a benchmark for assessing its rate of progression. It is of particular value in detecting the disorder in its early stages when other signs have not yet presented. Stages
Once keratoconus has been diagnosed, its degree may be classified by several metrics:
The steepness of greatest curvature from mild (< 45 D), advanced (up to 52 D) or severe (> 52 D);
The morphology of the cone: nipple (small: 5 mm and near-central), oval (larger, below-center and often sagging), or globus (more than 75% of cornea affected);
The corneal thickness from mild (> 506 μm) to advanced (< 446 μm).Increasing use of corneal topography has led to a decline in use of these terms. Treatment
Lenses
In early stages of keratoconus, glasses or soft contact lenses can suffice to correct for the mild astigmatism. As the condition progresses, these may no longer provide the person with a satisfactory degree of visual acuity, and most practitioners will move to manage the condition with rigid contact lenses, known as rigid, gas-permeable, (RGP) lenses.