Intacs is the trademark name for micro-thin implantable intracorneal ring inserts – a procedure used to improve mild myopia, also studied to determine its usefulness in reducing hyperopia, astigmatism and helping improve vision for those with keratoconus.
They are an alternative to laser surgery, and are tiny, crescent-shaped prescription devices made of plastic polymer which is a contact lens-like material (PMMA, also known as ICRS).
How many types are there?
There are three: Intacs, Ferrara and Bisantis. They differ by their size and shape. All are made in segments of Perspex (originally a full 360 degree ring when first developed).The differences are in diameter and shape. Intacs are the largest in diameter, Ferrara in between and Bisantis the smallest. Intacs are hexagonal in cross-section, Ferrara rings are triangular and Bisantis are oval.
Intacs have been used for Keratoconus since around 1999 and were originally FDA approved in 2004, and achieved CE status in Europe and NICE in the UK with some studies lasting more than 10 years, for the treatment of keratoconus. Results of Intacs for keratoconus treatment have been encouraging, especially in patients unable to tolerate contact lenses or in need of a corneal transplant/graft.
In US clinical studies, 97% of patients saw 20/40 or better with Intacs®, 74% saw 20/20 or better, and 53% saw 20/16 or better.
Similarly, in Iran, researchers found Intacs to be a safe and effective treatment option for patients who have keratoconus and contact lens intolerance. In this study, 37 eyes of 36 patients with moderate to severe keratoconus, clear central cornea and contact lens intolerance underwent Intacs placement. Postoperative examinations demonstrated a clinically significant improvement in both uncorrected distance visual acuity and best-corrected distance visual acuity. Both had a continuous improvement throughout the follow-up period – See more at: http://www.revophth.com/content/t/cornea/c/37805/#sthash.yLxanUyy.dpuf
Who is suitable and who is not?
Those with clear central corneas (although some reports of benefits in eyes with small scars), corneal thickness of 0.45mm or more at the insertion site, those with corneas flatter than 57D (best about 53D with a relatively low level of short sight) for Intacs, although the new SK type is designed for levels above this (including over 60D).
The inserts are surgically implanted in the periphery of the cornea at the outer edge of the cornea so that the centre of the cornea remains untouched. They are usually not noticeable and require no maintenance, unlike contact lenses. The effect they have is to flatten the cornea, allowing better focusing and providing crisp vision. Intacs inserts can be removed safely and replaced if a prescription changes. Removal of Intacs causes a patient’s eyes to regress to the condition they were in before insertion in most cases.
Unlike procedures such as LASIK, the insertion of Intacs causes the cornea to generally flatten. In addition, Intacs can decrease the irregular astigmatism found in keratoconus, but Intacs do not generally correct astigmatism, so if you have significant astigmatism they will not correct your vision without you needing to wear a contact or spectacles postoperatively. The primary goal of Intacs in keratoconus is to make the eye tolerant of wearing contact lenses and to avoid corneal transplantation. Other goals are to improve vision with glasses as well as uncorrected vision (without glasses or contact lenses). The goal of Intacs varies with the severity of your problem.
People with post LASIK corneal ectasia may also benefit from having Intacs fitted. Those who should not undergo an Intacs procedure include people who are under 21 years old, pregnant women, people who can still see well with contact lenses, people whose central corneas are not clear, people who have other eye health problems that may cause future problems and people taking certain medications that may impair healing of the eye.
THE INTACS PROCEDURE
At the beginning of the procedure, topical numbing eye drops are used. An holder supports your eyelids to stop you blinking during the operation. A channel within the cornea is then prepared, into which the Intacs are inserted. This is done with a laser called an Intralase or with a special intra-corneal tunnelling instrument. Either way a suction ring is placed to stabilise the eye, and the channel is prepared for the Intacs, which are then inserted.
Some patients may have 2 Intacs placed in each eye, others may have only one placed depending on the individual cornea. At the end of the procedure, a stitch or contact lens bandage is placed, more eye drops are given, and a plastic eye shield is offered for short term protection particularly at night. The eye drops used are to avoid infection and inflammation for at least a week and are usually cortisteroids.
Vision can start to improve the day after the procedure but may change for several days. Most people can go back to work a few days after the procedure. During your subsequent check ups, they might look to change the Intacs size or position, or doing other procedures such as CK, and other techniques. Intacs are not necessarily a one off procedure, other treatment might be necessary over time to enhance and optimise the final results.
Can you feel them after they are implanted?
No, although there can be a temporary feeling of ‘stiffness’ associated with nerve damage at insertion. The nerve damage will heal over a period of several weeks.
- Can be removed and replaced with new prescription if needed
- Improvement in vision occurs for most people within the first day
- No tissue removal
- No ongoing maintenance, unlike contact lenses
- Does not change curvature of cornea, may even flatten it
- The patient cannot feel the implants once they are inserted
- 97 percent of people who have Intacs have driver’s license vision without the need for eyeglasses or contact lenses
- Over 50% of people who have Intacs have 20/20 vision or better
- Free in the UK on the NHS
- Not suitable for everyone with keratoconus, especially advanced cases
- Risks are involved with the actual procedure, but not more than with any other type of eye surgery. For example, there is a risk of infection, overcorrection, blurry vision, double vision, corneal blood vessels, halos, glare, and fluctuating distance vision.
- Surgery does not work on all patients, and new treatment methods may need to be explored.
- Expensive; usually not covered by vision insurance plans (USA)
Possible side effects with Intacs
As with all surgery there are many, but most are rare or very rare. Discomfort/ pain up to 48hrs which can be treated with medication, blurred or fluctuating vision and tearing with light sensitivity and dryness. The rings may move and need repositioning. Infection is very rare.
Some may have to be removed after a while (5.0% to 10.0%) and the eye should return fully to how it was before surgery, which was its main attraction in surgery for short sight. Because some patients respond and heal differently, results can vary. In addition, other optical side effects include halos around lights and glare, especially at night.
Intacs with collagen cross linking cxl
Collagen cross-linking (CXL) aims to strengthen a thinning cornea and stop the keratoconus progressing. CXL can be combined with Intacs to further flatten the corneal curvature. The Intacs inserts effectively reverse whatever keratoconus steepening had occurred before the treatment, and the CXL stops it getting worse.
In the USA Holcomb C3-R is used by some doctors which is epi on CXL, followed by Intacs insertion to further improve vision. The European standard (thought to be more effective long term is epi off CXL, and sometimes Intacs are also added before of after the CXL procedure.
Majid Moshirfar, MD, notes that questions remain regarding which procedure should be done first. “For mild keratoconus, especially if a patient is young, I will do collagen cross-linking,” he says. “On the other hand, if the patient is middle-aged and has moderate keratoconus, I will most likely place the Intacs first. Some surgeons are creating the channels for the Intacs with the femtosecond laser or their mechanical system, and then they inject the riboflavin into the channels and then they put the rings in simultaneously,” says Dr. Moshirfar, a professor of ophthalmology at the John A. Moran Eye Center in Salt Lake City, Utah.
A study conducted in Turkey has found that combined Intacs placement and corneal collagen cross-linking treatment with intracorneal riboflavin injection was effective in keratoconic eyes. The study concluded that “intracorneal riboflavin injection into the tunnel was safe and may provide more penetration without epithelial removal.”
This study included 131 eyes in 105 patients with a mean follow-up of 7.07 months. The mean improvement was 0.26 ±0.16 logMAR in uncorrected distance visual acuity and 0.24 ±0.16 logMAR in corrected distance visual acuity.
A recent study conducted in Canada found that the combination of Intacs placement followed by sequential same-day PRK and collagen cross-linking may be a reasonable option for improving visual acuity in some patients with keratoconus.
The study included five eyes in four patients. All eyes first underwent laser-enabled placement of Intacs, followed by same-day PRK and collagen cross-linking. Six months after the procedures, significant improvements were seen with regard to uncorrected and corrected distance visual acuity, spherical equivalent refraction, keratometry and total aberrations. None of the patients lost lines of corrected distance visual acuity or developed haze.
Intacs are not right for everyone but certainly worth asking about to see if they can help you. To chat to people who have had Intacs join KeratoconusGB on Facebook and Twitter @keratoconusGB