Is Keratoconus Different from Corneal Ectasia?
January 10, 2025
If you have keratoconus, an eye doctor may have also mentioned that you have corneal ectasia. Confused? Read on to understand the difference.
Corneal ectasia is an umbrella term
Corneal ectasia, also called keratectasia, encompasses several different conditions where the cornea — the front clear dome of the eye — is abnormally thin, weak, and bulges outward. A distorted cornea bends light unevenly into the eye, causing reduced vision and commonly requiring custom rigid scleral contact lenses to rehabilitate vision. Keratoconus is just one type of corneal ectasia.
The different types of corneal ectasia
- Keratoconus. This is the most common corneal ectasia. Keratoconus is a naturally occurring eye disease affecting one in several hundred and it has a genetic predisposition. A minority with keratoconus shows a pattern of distortion called pellucid marginal degeneration. Although pellucid marginal degeneration used to be thought of as a separate eye disease, the global consensus today is that pellucid marginal degeneration is a variant of keratoconus.
- Post-LASIK ectasia. Also called post-LASIK keratectasia, LASIK-induced keratoconus, and iatrogenic keratectasia. This is one of the most feared complications of LASIK, and fortunately very few carefully selected patients experience this result. In post-LASIK ectasia, an otherwise healthy cornea responds abnormally to the laser vision correction, ending up thinner and weaker than expected and bulging outward. This is a disappointing outcome since most undergoing laser vision correction expect to reduce their dependency on eyeglasses and disposable soft contact lenses. Instead, most with post-LASIK ectasia end up needing custom rigid scleral contact lenses to regain sufficient vision. Post-LASIK ectasia is caused by surgery and is not naturally occurring.
- Keratoglobus. This is an extraordinarily rare corneal ectasia. Most eye doctors will not have a single patient with keratoglobus during their career. This is the one type of corneal ectasia where the eye is at risk of perforating.
- Terrien’s Marginal Degeneration. This form of corneal thinning is rare and occurs in the periphery of the cornea. The cause is unknown. Like all the other corneal ectasias, rigid surface contact lenses are the mainstay to restore vision.
Distinguishing post-LASIK ectasia from keratoconus is important
Knowing if you have post-LASIK ectasia or keratoconus influences likelihood of other family members getting your eye condition. It also can determine if you qualify for medically necessary contact lenses.
If you indeed have post-LASIK ectasia, your blood relatives are not at a higher risk for developing keratoconus. Yet if you have keratoconus, there is at least a 15 times greater risk that someone else in your family has keratoconus and you should inform the rest of your family to request screening for keratoconus during their eye examinations. What gets confusing is that some that develop corneal ectasia after LASIK could have had undetected mild keratoconus which was exacerbated by the surgery.
Since LASIK is an elective surgery, contact lens prescribing to manage complications from LASIK is not always covered by third-party payors including specific vision plans. In general, vision plans are apt to provide necessary contact lens approval for keratoconus. Proper diagnosis and documentation by your clinician and clinic staff are required for necessary contact lens authorization approval, which many offices do not routinely handle. If not done properly, these claims can get denied and clawed back in an audit, causing you frustration and increased cost in the long run.
ReVision Optometry is a referral-based practice in San Diego providing contact lens services for patients with keratoconus. To schedule an appointment, request your appointment online, or call our office at 619.299.6064.