Keratoconus
Keratoconus is a progressive degeneration of the cornea in which the cornea will get thinner and thinner and bulge out like a cone. People who are at high risk of developing the disease include: presence of eye allergies[1], RGP wearer[2], vigorous eye rubbing[1] and have family history of the disease[2]. This disease affects both male and female, often presents at teenage and progresses until mid-age.
Early keratoconus is difficult to detect. When the disease progresses, the amount of shortsightedness and astigmatism also increase. The vision with glasses becomes worse and image becomes distorted as the cornea changes from a regular surface to a very irregular surface. RGP can help to restore vision but in advanced situation, RGP may be intolerant and corneal transplant is required.
Treatments
Rigid gas permeable contact lens (RGP/ GP)
RGP, due to its rigid nature, tear is trapped between the lens and the irregular cornea surface which allows the smooth lens surface to provide clear vision to the patient. Despite it is less comfortable, a good fit RGP can greatly reduce the impact to vision due to keratoconus. RGP fitting in keratoconic eye can be very challenging and time consuming. Therefore, frequent revisits are expected especially when the disease progresses.
Hybrid contact lens
By combining a RGP (central) with a soft contact lens (peripheral), the hybrid contact lens is a new approach in treating keratoconus. ClearKone hybrid lens (SynergEyes Inc., CA, USA) not only provides the visual correction of RGP, it also provides high comfortability of soft contact lens. Since the soft lens skirt is in good contact with the eye, the lens fitting is much better than RGP and vision is more stable.
Corneal cross-linking (CXL)
Corneal cross-linking is a surgical procedure aims to strength the cornea in order to stop/slow down the degeneration of the cornea. It is proven effective in stabilizing the disease and improving vision.[3] All the patient has to do is to look at a blue light. The ophthalmologist will instill riboflavin frequently on the eye. The whole procedure takes about 30 minutes. Patients are advised to receive CXL treatment as soon as they are diagnosed with keratoconus. The earlier the treatment, the better the prognosis. When the cornea is getting too thin, CXL is not possible.
Intracorneal ring (ICR)
Intracorneal ring segments are implanted in the deep stromal cornea which aim to flatten the cone area and hence reduce astigmatism. It is again a surgical procedure in which the outcome is less predictable.
To help patient in visual and refractive rehabilitation, ophthalmologists may offer combination of treatments. For example, CXL with ICR or RGP/Hybrid lens. With a stable cornea after CXL, LASIK to correct residual refractive error may also possible.