Most people who undergo LASIK (laser in situ keratomileusis) can usually expect a quick recovery with few or no lasting complications. Even when negative side effects do occur following LASIK, they are usually not severe. Unfortunately, one exception to this is the incidence of post-LASIK ectasia.
Like keratoconus, post-LASIK ectasia is a form of corneal distortion in which the cornea is weak, thin and bulging. In keratotconus, this deterioration occurs naturally. But in cases of post-LASIK ectasia, the corneal tissue undergoes changes as a result of the procedure. In either case, the outcome is visual deterioration due to irregularities in the front refracting surface of the eye, called the cornea.
The good news is that, thanks to newer technology, ectasia is far less common than it was in the early days of refractive surgery. Furthermore, when it does occur, doctors are better equipped to treat it.
What Causes Post-LASIK Ectasia?
Some areas of the cornea are stronger than others. During LASIK, a corneal flap is created and part of the corneal tissue is removed. This reduces corneal biomechanical strength. In most patients, this does not pose a problem, but in those with certain risk factors, the depth and diameter of this cutting is more than the cornea can bear. The result is a weakened, misshapen cornea.
Over the years, surgeons have gotten much better at identifying which patients are at greatest risk of having this negative response. For example, if you have a thin cornea to begin with, you will likely be disqualified from having LASIK. Diagnostic instruments, called topographers, map the cornea and offer other important clues about the integrity of its surface. Other risk factors include high myopia, young age at the time of surgery, and high intraocular pressure (IOP).
How Is Post-LASIK Ectasia Diagnosed?
People who have LASIK surgery are required to return to their eye doctor several times in the days and months following the procedure. During this time, you will be monitored closely for any abnormal corneal changes. Signs of post-LASIK ectasia that would concern your doctor include increasing myopia, astigmatism, loss of uncorrected visual acuity, loss of best-corrected visual acuity, keratometric steepening, central and paracentral corneal thinning, and topographic evidence of asymmetric inferior corneal steepening. These signs may begin to appear as soon as one week after surgery, though in some cases, the changes occur more slowly and are noticeable several years after you have had LASIK.
If you start to notice vision loss, glare or ghosting around images after you’ve had LASIK, notify your doctor so you can be evaluated for ectasia.
Scleral Lenses for Post-LASIK Ectasia
Since glasses can not compensate for significant corneal irregularities, for years people suffering with post-LASIK corneal ectasia have turned to specialty contact lenses to address their unique visual needs. Gas permeable (GP) lenses, commonly referred to as “rigid” or “hard” lenses, are often used for this purpose. These lenses act as the primary optical surface of the eye and mask corneal surface irregularities.
More recently, scleral lenses are offering new hope for people with post-LASIK corneal ectasia. A scleral lens is a type of GP lens, featuring a large-diameter that allows the lens to rest on the white part of the eye, known as the sclera. Unlike traditional, small diameter GP lenses that rest on the highly innervated and sensitive cornea, the scleral lens vaults over the cornea and is much more comfortable than its smaller diameter counterpart.
Another feature that adds to comfort with a scleral lens is the liquid buffer that exists between the back of the lens and the front of the eye. Liquid fills this space and can help protect your corneal tissue.
Surgical Treatments and Interventions for Post-LASIK Ectasia
There are also a number of surgical options for the management post-LASIK ectasia. These include intracorneal ring segments such as Intacs, penetrating keratoplasty, and corneal collagen crosslinking.
If you have been diagnosed with post-surgical ectasia, you may be a good candidate for scleral lenses. Your eye doctor will work with you to help determine the most appropriate and least invasive management strategy to help provide stable, comfortable vision.