Author: Dr Val Phua MBBS, MMed (Ophth), FRCOphth, FAMS
Photo by: Freepik
Astigmatism (散光) is a common refractive problem and majority of people have it to some degree. If present in small amounts, it may not be visually significant and can be left alone. Higher amounts of astigmatism can cause blurry vision and require correction to achieve clear, sharp vision.
Astigmatism typically arises due to an irregularly shaped cornea. Instead of a basketball, the cornea may be shaped more like a rugby ball with one “meridian” steeper than the other. This causes light to be poorly focused on the retina and as a result, vision is blurred when looking at near or distance objects. In some cases, astigmatism may rise due to irregularities on the natural lens in the eye on top of changes in the cornea. Astigmatism can occur with either short or long-sightedness and most people require glasses or specialised contacts lenses to correct them but those are not the only options.
Laser vision correction encompass a spectrum of procedures including PRK, LASIK and SMILE which are able to correct the short or long-sightedness together with astigmatism at the same sitting. Having astigmatism does not disqualify you from this chance to be free from glasses or contact lenses. There is however more than meets the eye.
If this astigmatism when detected with specialised scans of the cornea is found to be too high or too irregular (think half inflated rugby ball), it may point to a more serious disease of the eye that has gone undetected and proceeding with laser vision correction may result in more potential issues than it solves. More specifically, highly irregular astigmatism can point to ectatic disorders of the cornea like keratoconus. This condition is progressive and requires specialised treatment to restore vision. In severe cases a corneal transplant may be needed. Keratoconus may also be associated with other conditions like allergic eye and retinal degenerations and warrants a thorough evaluation by your friendly ophthalmologist.
In many cases, laser vision correction is a safe and effective option to treat astigmatism. However, before undergoing any of the procedures, a thorough ophthalmic history, examination and specialised tests which highlight the suitability for each procedure for your eye should be done before proceeding.