Surgery Section - Implantation of Intrastromal Corneal Ring Segments

IMPORTANT REMINDER

This Medical Policy has been developed through consideration of medical necessity, generally accepted standards of medical practice, and review of medical literature and government approval status.

Benefit determinations should be based in all cases on the applicable contract language. To the extent there are any conflicts between these guidelines and the contract language, the contract language will control.

The purpose of medical policy is to provide a guide to coverage. Medical Policy is not intended to dictate to providers how to practice medicine. Providers are expected to exercise their medical judgment in providing the most appropriate care.

Description

Intrastromal corneal ring segments consist of micro-thin methylmethacrylate inserts of variable thickness that are placed circumferentially into two thirds depth of the peripheral corneal stroma. They have been investigated for two indications: a refractive surgery to correct mild myopia, and as a treatment of keratoconus.

In myopia, the intrastromal inserts correct myopia by flattening the center of the cornea and represent an alternative to laser in situ keratomileusis (LASIK) and other refractive surgeries. The proposed advantages of the intrastromal corneal rings are that their insertion does not affect the central cornea and thus their effect is not related to the healing process in the cornea. No corneal tissue is removed and the implants are reversible.

Keratoconus is a progressive bilateral dystrophy that is characterized by paracentral steepening and stromal thinning that impairs visual acuity. Initial treatment often consists of hard contact lenses. A penetrating keratoplasty (i.e., corneal grafting) is the next line of treatment in those patients who develop intolerance to contact lenses. While visual acuity is typically improved with a keratoplasty, there is an associated risk of perioperative complications, long term topical steroid use is required and endothelial cell loss occurs over time, which is a particular concern for younger patients. As an alternative, a variety of keratorefractive procedures have been attempted, broadly divided into subtractive and additive techniques. Subtractive techniques include photorefractive keratectomy or LASIK, but in general results of these techniques have been poor. Implantation of intrastromal corneal ring segments represents an additive technique where the implants are intended to reinforce the cornea, prevent further deterioration and potentially obviate the need for penetrating keratoplasty. This technique has primarily been investigated in patients in whom the cornea has remained transparent and who are intolerant of contact lenses.

INTACS®® represent an intrastromal corneal ring that has received FDA approval for two indications:

1. In 1999, INTACS® were approved through a pre market approval process (PMA) for the following indication:

"The KeraVision INTACS® are intended for the reduction or elimination of mild myopia (-1.00 to -3.00 diopters spherical equivalent at the spectacle plane) in patients:

1. Who are 21 years of age or older
2. With documented stability of refraction as demonstrated by a change of less than or equal to 0.50d for at least 12 months prior to the preoperative examination; and
3. Where the astigmatic component is +1.00 diopter or less."

2. In 2004, INTACS® received an additional FDA approval through the Humanitarian Device Exemption (HDE) process for the following indication:

"This device is indicated for the reduction or elimination of myopia and astigmatism in patients with keratoconus, who are no longer able to achieve adequate vision with their contact lenses or spectacles, so that their functional vision may be restored and the need for a corneal transplant procedure may potentially be deferred. The specific set of keratoconic patients proposed to be treated with INTACS® prescription inserts are those patients:

1. Who have experienced a progressive deterioration in their vision, such that they can no longer achieve adequate functional vision on a daily basis with their contact lenses or spectacle.
2. Who are 21 years of age or older
3. Who have clear central cornea
4. Who have a corneal thickness of 450 microns or greater at the proposed incision site; AND
5. Who have whole corneal transplantation as the only remaining option to improve their functional vision.

Note: The humanitarian device exemption (HDE) does not require the manufacturer to provide data confirming the efficacy of the device, but rather data supporting its “probably” benefit. The HDE process is available for devices treating conditions that affect less than 4,000 Americans per year.

Policy/Criteria

1. Implantation of intrastromal corneal ring segments may be considered medically necessary for the treatment of keratoconus when all of the following criteria are met:
   1. Functional vision cannot be achieved with contact lenses or spectacles
   2. Twenty-one years of age or older
   3. Clear central cornea
   4. Corneal transplantation is the only other remaining option to improve functional vision
2. Implantation of intrastromal corneal ring segments is considered not medically necessary as a treatment of myopia.

Scientific Background

Myopia

The FDA approval for the INTACS® device was based on results of a multi-institutional study involving 361 subjects with mild myopia. (2) Subsequently, the two-year results of this study were published in the peer reviewed literature. (3) This data suggested that the intrastromal rings predictably and effectively reduced or eliminated mild myopia (-1.00 to -3.00 d); the refractive effect was stable over time. However, mild myopia is effectively treated with either spectacles or contact lenses. Therefore, this application of intrastromal corneal implants is considered not medically necessary. Additionally, as noted in the Important Reminder section, benefit determinations are based on the applicable contract language. Many Plan benefits contain a specific exclusion for refractive eye procedures.

Keratoconus

The published data regarding intrastromal corneal implants for keratoconus consist of  prospective and retrospective case series, with the largest case series including 127 patients. (4) Ibrahim reported on the five year outcomes in 186 eyes of 127 patients with a follow-up of five years.  The average age was 28.9 years and all patients were unable to achieve functional vision with spectacles or contact lenses prior to implantation of corneal ring segments.  In terms of uncorrected visual acuity at three months and five years a total of 85.3% and 85.2% gained lines on vision exams.  In terms of best-corrected visual acuity 87.9% and 86.1% respectively gained at least one line at three months and five years.   Boxer Wachler and colleagues reported on the outcomes in 74 eyes of 50 patients with a mean follow up of nine months. (5) A total of 45% gained at least two lines of best spectacle corrected visual acuity (BSCVA), 51% of patients had no change and 4% lost BSCVA.  Siganos and colleagues studied 33 eyes in 26 patients at a mean follow up of 11.3 months. (6) In this study 25 eyes recorded a one to six line gain in BSCVA, while four eyes remained unchanged and four eyes experienced a loss.  Colin and colleagues reported statistically significant improvement in BSCVA up to 24 months in 96% of patients.  A number of patients in this study showed progressive improvement over time. (7)  Alio and colleagues published three year outcomes in 13 eyes of eleven patients. (8) The BSCVA improved significantly at six months and remained stable throughout the 36 month.

Given the rare occurrence of keratoconus it is not expected that well-designed, randomized trials are possible.  The small studies that are available consistently report excellent outcomes with corneal ring segments for up to five years with few patients requiring corneal transplant.  Corneal ring segment implantation is less invasive and is associated with significantly less morbidity than corneal transplant.  Given these conditions it is determined that the technology evaluation criteria are met for implantation of corneal ring segments in the treatment of keratoconus in patients whose only remaining option for functional vision is corneal transplantation.

An updated search of the literature through September 8, 2008 did not return any new clinical trial data that would result in a policy change.

References

1. BlueCross and BlueShield Association Medical Policy Reference Manual, Policy No. 9.03.14
2. www.fda.gov/cdrh/pdf/p980031b.pdf   (Verified 09/08/08)
3. Schanzlin DJ, Abbott RL, Asbell PA et al. Two year outcomes of intrastromal corneal ring segments for the correction of myopia. Ophthalmol 2001;108:1688-1694
4. Ibrahim TA. After 5 years follow-up: Do Intacs help in keratoconus? J  Cataract Refract Surg 2006:45-48
5. Boxer Wachler BS, Christie JP, Chandra NS, et al. INTACS for keratoconus. Ophthalmology 2003;110(5):1031-40
6. Siganos CS, Kymionis GD, Kartakis N, et al. Management of keratoconus with INTACS®. Am J Ophthalmol 2003;135(1):64-70
7. Colin J. European clinical evaluation: Use of Intacs for the treatment of keratoconus. J Cataract Refract Surg 2006;32(5):747-55
8. Alio JL, Shabayek MH, Artola A. Intracorneal ring segments for keratoconus correction: Long-term follow-up. J Cataract Refract Surg 2006;32(5):978-85

Cross References

Phototherapeutic Keratectomy, Regence Medical Policy Manual, Surgery, Policy No. 95

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