Corneal Ectasia: What Is It, Types & How to Treat

Corneal ectasia involves corneal thinning. It refers to a collection of uncommon corneal conditions that can cause the eye to bulge. 

Three of the most common causes are keratoconus, eye surgery, and poor-fitting contacts.

Corneal ectasia can be serious, so it is essential to seek a medical diagnosis and professional treatment.

Types of Corneal Ectasia Disorders

There are several disorders included in corneal ectasia. These uncommon conditions typically cause thinning of the cornea. 

• Keratoconus: This is bulging of the eye and the most common type of corneal ectasia disorder. 
• Keratoglobus: This is thinning of the cornea and a globular bulge of the cornea. Keratoglobus is a rare noninflammatory disorder.
• Post-LASIK ectasia: This can be a complication of LASIK surgery, typically because too much corneal tissue was removed.
• Pellucid marginal degeneration (PMD): This is a non-inflammatory disorder with thinning of the inferior cornea, affecting both eyes.
• Terrien’s marginal degeneration: This is a non-inflammatory progressive thinning of the peripheral corneal layers. 

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Causes

There are various causes of corneal ectasia, ranging from hereditary factors to injuries. Here are some of the most common:

Keratoconus

According to the Review of Optometry, keratoconus is the most common cause of ectasia and is found in between 50 to 230 people per 100,000. 

This is a condition where the collagen fibers of the cornea become weak. The progressive condition creates a cone shape in the eye, as the fibers cannot effectively hold the eye in its natural dome.

Postoperative Issues

Ectasia may be caused by eye surgeries, such as LASIK and PRK. The problem occurs if too much corneal tissue is removed during surgery. The cornea can become weak and due to thinning tissue, the eye bulges.

Poorly Fitting Contacts

If contact lenses do not fit properly, they can cause corneal ectasia. Contacts may be too soft or too rigid and affect the shape of the eye. This molding of the cornea creates further problems with vision.

Symptoms of Corneal Ectasia

Symptoms tend to progress from mild to moderate to severe. The signs of a bulging cornea are often accompanied with the following:

• Seeing shadows in the visual field
• Seeing ghostly images
• Squinting a lot to see clearly
• Changing prescriptions very frequently
• Not getting full vision correction with glasses or contacts
• Watery eyes
• Blurry vision

Diagnosis

Clinical tests are used to confirm the diagnosis of corneal ectasia and evaluate the underlying cause. Optometrists use precise and painless tests to measure the shape and thickness of the cornea. 

According to the American Academy of Ophthalmology, it is possible to evaluate ectasia risk with preoperative testing. Testing may include topography or tomography and pachymetry indexes to identify a risk score. 

Corneal topography is a diagnostic test that helps your doctor understand details about the thickness and steepness of the cornea. 

Optical coherence tomography (OCT) is a painless test that shows the profile of the cornea. Corneal tomography uses special rotating imaging to understand the curvature, thickness, and elevation variations in the cornea.

Specular microscopy involves another painless test that evaluates the health of cells at the back of the cornea. 

Diagnostic testing may also be combined with monitoring the condition to evaluate changes, progression rate, and treatment options. 

Post-LASIK Ectasia

Corneal ectasia is considered one of the most concerning complications that may occur after LASIK surgery. LASIK surgery has evolved, and technology continues to improve, so cases of corneal ectasia are rare, but there is still risk of this complication. 

Rigorous screening before a LASIK operation is essential to evaluate risks. Unfortunately, even with in-depth screening, ectasia may occur. According to research cited in the Review of Optometry, 32 percent of patients who develop ectasia had normal preoperative tests. 

Talk with your optometrist to evaluate your risk level before getting eye surgery. Discuss the possible outcomes with your surgeon to fully understand your risk assessment. 

Treatment strategies for corneal ectasia continue to evolve. Research confirms that early diagnosis and management are critical to prevent the condition from progressing and preserving vision.

Treatment for Corneal Ectasia

Treatment for corneal ectasia will depend on the severity of the condition. Options range from an observation approach to surgery.

Corneal Cross-Linking

Corneal cross-linking (CXL) is an outpatient procedure that strengthens and stabilizes the cornea. This is a minimally invasive procedure that uses exposure to UV light, eye drops, and gentle brushing of the corneal surface with a vitamin B2 solution. This all helps to strengthen the cornea.

INTACs

INTACs are tiny implants placed around the cornea to reduce the bulging shape. This is one alternative to a corneal transplant, which is considered to have more risks. 

After INTACs are placed in the eye, people may be able to comfortably wear contact lenses. While strengthening the shape of the eye, this procedure does not necessarily mean that you will be able to see without corrective eyewear.

Corneal Transplants

Corneal transplants may be a treatment choice for moderate and severe cases of corneal ectasia. Different approaches to corneal transplants are available depending on the individual diagnosis and the severity of the condition.

Corneal Ectasia FAQs

What is ectasia in the eyes? 

Ectasia is when the cornea is weakened and thin, and it starts bulging. The condition can occur due to a variety of causes, such as keratoconus or if too much tissue is removed during a LASIK procedure.

How do you treat corneal ectasia?

Treatment varies depending on the severity and progression of the condition, individual health, and underlying cause. Treatments include corneal cross-linking, INTACs, and corneal transplants.

How common is post-LASIK ectasia?

Corneal ectasia following LASIK is very rare. Studies show it occurs in 0.2 percent of cases. Preoperative diagnosis is essential to evaluate individual risk.

References

1. Keratoconus: Overview and Update on Treatment. (January–March 2010). Middle East African Journal of Ophthalmology.

2. Keratoglobus. (September 2013). Eye.

3. Ectasia After LASIK. (October 2021). American Academy of Ophthalmology.

4. Terrien’s Marginal Degeneration. American Academy of Ophthalmology.

5. Firm Up Your Approach to Corneal Ectasia. (April 2015). Review of Optometry.

6. Recognizing the Signs of Corneal Ectasia. (September 2005). Review of Ophthalmology.

7. Keratoconus. National Health Service.

8. Ectasia Risk in Topography. (May 2022). American Academy of Ophthalmology.

9. Corneal Topography. American Academy of Ophthalmology.

10. Corneal Tomography. American Academy of Ophthalmology.

11. Optical, Ultrasound Pachymetry Interchangeable in Glaucoma. (March 2019). Review of Optometry.

12. Corneal Ectasia Preferred Practice Pattern. (September 2018). American Academy of Ophthalmology.

13. Corneal Compromise: How to Assess the Risk of Post-LASIK Ectasia. (December 2018). Review of Optometry.

14. Treatment Strategies for Corneal Ectasia. (July 2010). Current Opinion in Ophthalmology.

15. Late Onset Corneal Ectasia After LASIK Surgery. (December 2011). Saudi Journal of Ophthalmology.