Intacs (Corneal Implants)

12 sources cited
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What are Intacs®?

Intacs® or intracorneal ring segments (ICRS) are thin, crescent-shaped, clear plastic rings inserted into the cornea to restore their shape. 

They are made of the same biocompatible material used in intraocular lenses (IOLs) for cataract surgery. Intacs have a low chance of complications.


What Conditions Can Intacs Treat? 

Intacs are inserted into the eyes during eye surgery to correct refractive errors associated with keratoconus, myopia (nearsightedness), and astigmatism.7

Intacs flatten the cornea in people with myopia. This refocuses light rays in the retina to improve vision. The retina is the part of the eye that senses light and sends images to the brain for interpretation.

In people with keratoconus, Intacs flatten the steep parts of the bulging cornea to correct vision distortions.

What is Keratoconus?

Initially, Intacs were used to correct mild myopia or nearsightedness (−1.0 to −3.0 diopters).1 In 2004, the U.S. Food and Drug Administration (FDA) granted a Humanitarian Device Exemption (HDE) to Intacs, which then allowed their use in treating keratoconus.

Keratoconus is the thinning and bulging of your cornea, the clear front layer of your eye. It commonly affects young people (ages 15 to 25) and progresses over time.

Someone suffering from keratoconus has a cone-shaped cornea and may experience vision problems. The condition commonly affects both eyes. However, one eye may be affected more than the other.

How Do Intacs Fix Keratoconus?

Intacs were approved to complement the few existing treatments for keratoconus, such as scleral lenses, corneal collagen cross-linking, and corneal transplant (keratoplasty).2 They can reduce or eliminate myopia or astigmatism in keratoconus patients who can no longer benefit from prescription eyeglasses or contact lenses.

According to eye experts, Intacs, in combination with corneal collagen cross-linking, effectively reduce astigmatism in myopic eyes.3 The combination of the two also offers the best treatment outcome in progressive keratoconus. 

The corneal cross-linking (CXL) procedure involves using vitamin B (riboflavin) and controlled UV rays to strengthen the corneal collagen fibers.4 This flattens and stabilizes the bulging cornea.

Recently, Intacs SK has been proven effective in correcting higher myopic and astigmatic refractive errors. This version of corneal inserts has a diameter of 6 mm and a round design to minimize glare.5 As a result, they're much smaller in diameter compared to the standard Intacs, which measure 6.8 mm in diameter.

Intacs are available in different thicknesses, ranging from 0.25 to 0.45 mm. Intacs SK are available in 0.21, 0.40, 0.45, and 0.50 mm thickness.6 They have a long-lasting outcome, just like intraocular lenses (IOLs).

Intacs Procedure: What to Expect

The Intacs procedure occurs on an outpatient basis, meaning you'll return home immediately afterwards. However, your ability to perform normal functions, such as driving, will be impaired for a few days. Ask someone to drive you to and from the surgeon's office.

Below is what to expect before, during, and after surgery:

Before Surgery

Before surgery, your doctor will ask you questions and conduct examinations to ensure you're fit for the procedure.8 The ideal candidate for Intacs:

  • Is at least 21 years or older
  • Has myopia or astigmatism
  • Has mild to moderate keratoconus
  • Has had a stable eye prescription for at least a year
  • Doesn’t have any underlying health conditions that affect the eyes

If you meet the above requirements, your surgeon will likely recommend surgery.

During Surgery

The procedure will take place in your doctor's office, where you’ll sit in a reclining chair. Your doctor will numb your eyes with topical anesthetic. They will then hold your eyelids open with a speculum to prevent blinking. 

Your surgeon will make a small incision on the surface of the cornea and place a centering guide to stabilize the eye. They will then separate the cornea's inner layers to create room for the Intacs.

After separating the layers, your doctor will insert the Intacs and close the incision with tiny stitches or tissue glue. The procedure takes about 15 minutes.

After Surgery

After surgery, your surgeon will apply eye drops to prevent infection or inflammation. They may also place clear plastic shields over your cornea for protection as it heals. 

You won't feel the Intacs because they're placed beneath the nerve endings. Intacs are also not noticeable to other people unless they look closely.

Your doctor will provide post-op care instructions to enhance your healing process. They will also prescribe pain medication and lubricating eye drops to ease discomfort after surgery.

A follow-up visit is highly recommended so your surgeon can monitor the healing process.

Note: The Intacs procedure is reversible in the case of unsatisfactory outcomes. Once removed, your eyes will return to their preoperative refractive errors.9

Outcomes and Success Rates of Intacs

The results of the procedure will depend on the extent of keratoconus. People with mild keratoconus may not need additional vision correction or the use of eyeglasses.

People with moderate keratoconus will require glasses or soft contact lenses after Intacs.

According to eye experts, Intacs have a success rate of about 90% in cases of progressive keratoconus. When combined with corneal collagen cross-linking, the results are remarkable in nearly all operated eyes.10

A European clinical evaluation of Intacs use also concluded that Intacs were safe and effective in keratoconus. According to the study, 74% of the Intacs recipients achieved a visual acuity of 20/40.11 Only 12% of recipients were dissatisfied with the procedure, requiring removal.

Studies conducted on Asian eyes also support these findings. They found that the Intacs procedure was safe and had positive outcomes among the study population.12 And, there were no significant complications with Intacs removal.

What are the Risks of Intacs?

Possible risks after an Intacs procedure include:

  • Eye infection
  • Problems with night vision
  • Halos or glares around lights
  • Blurry or fluctuating vision

Note: Pregnant women, people with systemic diseases, and people taking medications likely to interfere with surgery or healing are not eligible for Intacs.

How Much Do Intacs Cost?

The cost of Intacs is about $2,000 to $2,500 per eye. Cost may increase or decrease based on your location, the facility, and your surgeon's experience. 

Most insurance providers cover Intacs for treating keratoconus. So, expect to pay less if you have insurance coverage. Talk with your doctor and insurance company to determine the exact cost of the procedure.

Other Treatment Options

Here are six possible alternatives to Intacs:

  1. Eyeglasses or soft contact lenses. These correct vision problems in early-stage keratoconus.
  2. Gas permeable contact lenses (GP lenses). GP lenses replace the irregular curvature of the cornea with a smooth, uniform refracting surface that improves visual acuity.
  3. Piggyback lenses. These are hard contact lenses placed on soft ones to improve comfort.
  4. Hybrid contact lenses. These have a firm center with a soft ring around the circumference to increase comfort.
  5. Scleral contact lenses. These are placed on the sclera or white of the eye. They cover the cornea without contact to enhance comfort and improve visual acuity.
  6. Prosthetic lenses. These are specially designed through 3D imaging to match the exact impression of your sclera. They correct vision in a manner similar to scleral lenses.
12 Cited Research Articles
  1. Jackson M.,“Intacs: Do they work and whatever happened to them?,”  Healio, 06 May. 2019
  2. Boyd K.,“About Corneal Transplantation,” American Academy of Ophthalmology, 13 Sep.2021
  3. Lindstrom R.,“Intacs, cross-linking together reduce astigmatism,” Healio,  28 Oct. 2019
  4.  Skinner, A.,“Non Cross-linking Options for Keratoconus,” Review of Ophthalmology, 10 Jun. 2019
  5. Kotb A. and Hantera M.,“Efficacy and Safety of Intacs SK in Moderate to Severe Keratoconus,” National Center for Biotechnology Information (NCBI), Mar. 2013
  6. Shetty et al.,“Decision making nomogram for intrastromal corneal ring segments in keratoconus,” Indian Journal of Ophthalmology,  Jan. 2014
  7.  Levinger S. and Pokroy R. “Keratoconus Managed With Intacs:One-Year Results,” American Medical Association. 01 Oct. 2005
  8. American Medical Association,”  The University of Texas Southwestern Medical Center
  9. Intacs refractive effect can be easily ‘reversed,” Healio 01 Sep. 2000
  10. Joubert K.,“Reviving the lost art of manual Intacs implantation,” Healio 09 Oct. 2019
  11. Joseph C., “European clinical evaluation: Use of Intacs for the treatment of keratoconus,” JCRS
  12. Shetty et al.,“Safety and efficacy of Intacs in Indian eyes with keratoconus: An initial report,” Indian Journal of Ophthalmology, Mar. 2009
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