Keratoconus (KC) is a disease in which the central portion of the cornea ( the so called ‘black portion of the eye’) begins to thin and bulge out. The cornea is responsible for focusing accurately most of the light coming into the eye and providing us with clear vision. Therefore, abnormalities of the cornea severely affect the way we see the world i.e haloes, double vision, ghost images, sensitivity to light may occur making simple tasks, like driving, watching TV or reading a book difficult.
What is the usual age of onset of keratoconus? How fast does it progress?
The age of onset of keratoconus can vary from early teens to people in their 40′s or older. Although cases in which keratoconus is first diagnosed at an earlier age usually result in more rapid progression, it is not unusual for the disease to progress upto a certain point and then stabilize on its own. The continued thinning of the cornea usually progresses slowly for 5 to 10 years and then tends to stop. Occasionally, it is rapidly progressive.
Does keratoconus affect both eyes?
Yes, in approximately 90% of keratoconus cases the disease will occur in both eyes. The rate of progression and the timing of the onset of the disease however is typically different for each eye.
What are the symptoms of keratoconus?
In its earliest stages, keratoconus causes slight blurring and distortion of vision and increased sensitivity to glare and light. These symptoms usually first appear in the late teens and early twenties.. Keratoconus patients can also experience light sensitivity, disturbed night vision, headaches from eye strain and reading problems. They may require frequent chane of glasses.
In the advanced stage, the patient may experience a sudden clouding of vision in one eye that clears over a period of weeks or months. This is called “acute hydrops” and is due to the sudden entry of fluid into the stretched cornea. In advanced cases, superficial scars form at the apex of the corneal bulge resulting in more vision impairment.
Can keratoconus cause blindness?
No, very few if any persons suffer from total blindness from keratoconus alone. But in severe cases, one’s vision can be significantly impaired and normal everyday activities may be difficult. However with the currently available treatment options most patients retain useful vision enabling them to lead normal productive lives.
What causes keratoconus?
The cause of keratoconus is still unknown despite our long experience with it. One scientific view is that keratoconus is developmental (i.e., genetic) in origin. This suggests that it is the consequence of an abnormality of growth, essentially a congenital defect. Another view is that KC represents a degenerative condition. A less widely held hypothesis suggests that the endocrine system may be involved because the disease usually is detected around puberty when a lot of hormonal changes usually occur in the body.Heredity influences in KC are suggested by studies that show that approximately 13% of patients have other family members with the disease.
What are the treatment options available?
Treatment options for keratoconus include:
- Spectacles / soft contact lenses in the initial stages.
- RGP (‘semi soft’) contact lenses in slightly more advanced cases when vision cannot be fully corrected with glasses or soft contact lenses.
- Customized lenses i.e Rose K contact lenses or Boston Scleral lenses ( these are useful for more advanced keratoconus in which regular RGP lenses do not fit well and tend to keep falling off),
- INTACS in which very thin rings are inserted in the cornea, to make its shape more regular. These help in better fitting of contact lenses or spectacles and also improve the quality of vision e.g in some cases as the cornea is very steep the lenses may keep falling off. But after INTACS the shape of the cornea becomes more regular and a good contact lens fit may now be possible.
- Collagen crosslinking with riboflavin and UVA light ( commonly known as C3R, CCL) is the only procedure available today to stop the progression of keratoconus. All other options listed above only treat the symptoms, but do not stop the disease process. In C3R vitamin B1( riboflavin) drops are put on the eye for 30 minutes and then the eye is exposed to ultra violet A light for the next 30 minutes. This procedure stiffens ie. strengthens the cornea by increasing the number of attachments between the fibres of the cornea. It is done only in cases where the keratoconus appears to be progressing.
- The standard procedure followed widely today takes about an hour. However more rapid variations of the procedure will soon become available, where the strength of UVA light is increased by about 3 times, and the duration of exposure reduced , so that the whole procedure may take only around 10 minutes or so.
- Corneal transplants i.e replacing the diseased cornea with the healthy cornea from a donor is required only in very advanced cases, where other treatment options are unable to improve vision. A lot of advancement has been made in this field so that highly customized surgery( i.e replacing only the diseased layer of the cornea , or using laser technology to cut the cornea) is possible with excellent and predictable results.