Lasik Eye Surgery for Astigmatism

Astigmatism is one of the most common eye disorders affecting huge swaths of the population where the skewed curvature of the corneal surface creates blurred images of near and distant objects. In the normal course, astigmatism goes hand in hand with varying degrees of nearsightedness (myopia) and farsightedness (hyperopia). All three eye problems are not diseases but different shades of refractive errors caused when light deviates abnormally through an imperfect cornea. Such disorders are normally corrected using glasses and contact lenses, but a third option is rapidly gaining popularity – laser surgery, more particularly Lasik (laser in situ keratomileusis) eye surgery.

FDA approves Lasik surgery for correcting refractive disorders

Lasik surgery became popular as an FDA approved technique for correction of refractive errors, a technique that uses a cold laser to vaporize layers of the corneal stroma to reshape the eye surface. The technique corrects the curvature of the cornea enabling normal 20/20 to near normal 20/40 vision without having to resort to prescription glasses and contacts. Lasik guarantees a quick and simple route to refractive error correction and near total freedom from the inconvenience of using eye-wear. This benefits people severely disadvantaged by eye-wear and who desire the comfort of near perfect vision without external aids that deglamorize their appearance.

The core reason for astigmatism – The misshapen cornea

The cornea is the glass-like transparent component of the eye which forms the outer dome-shaped layer protecting the inner iris, pupil and lens. It basically consists of three layers – an outer epithelium, a middle layer of thick stromal tissue and an inner endothelium that separates the cornea from the iris and pupil. The cornea normally appears like a dome with a smooth curving surface which is perfect for refracting incoming light accurately on the retinal wall at the back of the eye.

Changes occur in the cornea through aging, injury-related trauma or from eye disease. One such change is a condition called keratoconus where the cornea loses its thickness and dome-like shape becoming more conical. Instead of a spherical surface, we have a cornea with steeper sides that cause light rays to deviate abnormally.

As a result, light that would normally have refracted on a central point on the retina now refracts on multiple sites on the retina causing double images or blurred vision. This is the main reason why the eye strains to view distant and near objects in astigmatism.

Sometimes, the blurriness causes distant objects to remain unfocused as in nearsightedness (myopia). In certain cases, the person finds it difficult to focus on objects that are nearer to the eye as in farsightedness (hyperopia). In this manner, a slight difference in corneal curvature causes astigmatism combined with nearsightedness or farsightedness.

The difference in correcting astigmatism through eye-wear and lasers

Refractive errors are normally corrected using glasses and contacts which have their refractive index suitably calibrated to nullify the vision defect of the altered cornea. The vision appears normal only when the eye-wear is used, but the underlying cause of the refractive error and the altered cornea remains uncorrected. Lasik surgery changes all that by permanently reworking the curvature of the cornea using a laser to vaporize multiple layers of corneal stroma tissue. A cold beam of laser energy is programmed in an excimer laser to remove corneal tissues at predetermined locations. Pre-operation eye testing helps the surgeon pinpoint the precise locations where corneal vaporization is required. The procedure thins the cornea molding it into a spherical shape ideal for refracting incoming light correctly and accurately onto the retina.

How Laser scores over eye-wear in correcting astigmatism

People pursuing different careers may have severe misgivings about using eye-wear. Sports persons for example generally avoid eye-wear because it is cumbersome and difficult to handle, and may also result in injury, especially in close contact sports like wrestling and boxing. Industrial workers may also wish to avoid external aids as they need to be physically handled, maintained and serviced which may be impossible during working hours. For such people, correcting astigmatism through laser surgery is more appealing because of its permanency and freedom from the compulsion to use external aids.

In the majority of Lasik surgeries, the results are positive and the transformation in visual acuity is startling and immediate. This comes as a good news for people who are severely pressed for time and can safely resume their responsibilities within 24 hours of undergoing an outpatient surgery. The main precautions the doctor would advise is to use an eye shield for a few hours following the operation and sunglasses to keep out the glare. Eye drops will be necessary to keep the eyes moist and to protect the eye from infection and inflammation.

Many Lasik patients are thrilled that their astigmatism literally vanishes and they can go about their normal routine without having to reach for glasses or cumbersome contacts. It is a rewarding feeling to be in a position to drive your car safely and legally within 24 hours following Lasik surgery. People habituated in using contacts will be relieved of becoming free from the drudgery of applying, removing and servicing contacts while saving time.

Disadvantages of Lasik surgery as a cure for astigmatism

First of all, Lasik is not suited for all people and one has to qualify for the surgery by fulfilling certain conditions that could be ignored only at one’s peril.

It is widely believed that at a young age the eye is in a state of constant change and refractive errors if any, need time to stabilize before laser surgery is attempted. Astigmatism cannot be corrected in younger candidates for this reason.

You need to be free of eye diseases like glaucoma and cataract or conditions like keratoconus or corneal bulging. A diseased eye poses a genuine challenge – inconsistent and delayed healing. Corneal diseases frequently tend to change the surface curvature resulting in constant changes in the refractive error. Astigmatic error correction through surgery is feasible only if the underlying tissue remains stable and healthy.

Opting for Photorefractive keratectomy (PRK) over Lasik surgery to correct astigmatism

Lasik surgery requires a thicker cornea that can be safely reshaped leaving sufficient corneal tissues in reserve for contingencies. For patients who have much thinner corneas, a different kind of laser surgery called Photorefractive keratectomy (PRK) may be recommended to correct astigmatism. The basic difference is that PRK completely removes the outer epithelial covering of the cornea allowing the cells to regrow within a couple of days following surgery. This procedure requires more recovery time. In Lasik surgery, the epithelium is sliced and moved aside while it is still attached to the cornea like a flap which is then restored to its original position after surgery. It heals on its own. Both surgical techniques yield positive results and correct astigmatism but the caveat is that the eye must be in good overall health.  

The last word

Using eye-wear continues to be the simplest and the most practical method of correcting astigmatism, but one has to contend with frequent refractive changes that necessitate periodical checkups and changes in corrective eye-wear. Lasik offers an easy and practical solution – reshape the cornea in such a manner that astigmatism is permanently cured and become free from the compulsion to adjust to cumbersome contacts and deglamorizing glasses. The chief deciding factors will be your eligibility for Laser surgery, the cost benefit of availing laser treatment compared to regular eye-wear and the risks inherent in a major surgical procedure compared to the totally risk-free eye-wear option.