BlueCross and BlueShield of Montana Medical Policy/Codes
Implantation of Intrastromal Corneal Ring Segments
Chapter: Surgery: Procedures
Current Effective Date: August 27, 2013
Original Effective Date: November 07, 2008
Publish Date: August 27, 2013
Revised Dates: December 21, 2010; November 12, 2012; June 28, 2013

Intrastromal corneal ring segments consist of micro-thin soft plastic inserts of variable thickness that are placed in the periphery of the cornea.  Intrastromal corneal ring segments have been investigated as a means of improving vision in diseases such as keratoconus and pellucid marginal degeneration, and for refractive surgery to correct mild myopia.

Intrastromal corneal ring segments are flexible, crescent-shaped rings of polymethylmethacrylate that are placed in the periphery of the cornea.  An incision is made in the cornea and channels are created in it by rotating a lamellar dissector or by using a femtosecond laser.  One or two corneal implant segments are introduced to each channel, and various implants with a range of implant thicknesses are available for different degrees of correction.  They affect refraction in the eye by physically changing the shape of the cornea (flattening the front of the eye), thereby correcting the irregular corneal shape.  If required, the implants can be removed at a later date.

In myopia, 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 patients who develop intolerance to contact lenses.  While visual acuity is typically improved with keratoplasty, perioperative complications are an associated risk; long-term topical steroid use is required; and endothelial cell loss occurs over time, which is a particular concern in 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 in which the implants are intended to reinforce the cornea, prevent further deterioration, and potentially obviate the need for a penetrating keratoplasty.  This technique has primarily been investigated in patients in whom the cornea has remained transparent and who are intolerant of contact lenses.

Pellucid marginal degeneration is a non-inflammatory progressive degenerative disease, typically characterized by bilateral peripheral thinning (ectasia) of the inferior cornea.  Deterioration of visual function results from the irregular astigmatism induced by asymmetric distortion of the cornea, and visual acuity typically cannot be restored by using spherocylindrical lenses.  Rigid gas permeable contact lenses may be used to treat pellucid marginal degeneration.  Intracorneal ring segment implantation, crescentic lamellar keratoplasty, penetrating keratoplasty, and corneal wedge excision have also been proposed.

Regulatory Status

INTACS® represent an intrastromal corneal ring that has received approval by the U.S. Food and Drug Administration (FDA) for two indications.

In 1999, INTACS inserts were approved through a premarket approval process (PMA) for the following labeled 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:

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

In 2004, INTACS received an additional approval by the FDA through the humanitarian device exemption (HDE) process.

The INTACS 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 patients:

  • that 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 spectacles;
  • that are 21 years of age or older;
  • that have clear central corneas;
  • that have a corneal thickness of 450 microns or greater at the proposed incision site; AND
  • have corneal transplantation as the only remaining option to improve their functional vision.

NOTE: HDE does not require the manufacturer to provide data confirming the efficacy of the device, but rather data that supports its “probable” benefit.  The HDE process is available for devices treating conditions that affect fewer than 4,000 Americans per year.


Each benefit plan, summary plan description or contract defines which services are covered, which services are excluded, and which services are subject to dollar caps or other limitations, conditions or exclusions.  Members and their providers have the responsibility for consulting the member's benefit plan, summary plan description or contract to determine if there is any exclusion or other benefit limitations applicable to this service or supply.  If there is a discrepancy between a Medical Policy and a member's benefit plan, summary plan description or contract, the benefit plan, summary plan description or contract will govern.

Medically Necessary

Blue Cross and Blue Shield of Montana (BCBSMT) may consider implantation of intrastromal corneal ring segments medically necessary for the treatment of keratoconus in patients 21 years of age or older who meet the following criteria:

  • The patient has experienced a progressive deterioration in their vision, such that they can no longer achieve adequate functional vision with contact lenses or spectacles; AND
  • Corneal transplantation is the only alternative to improve their functional vision; AND
  • The patient has a clear central cornea with a corneal thickness of 450 microns or greater at the proposed incision site.

Not Medically Necessary

BCBSMT considers implantation of intrastromal corneal ring segments not medically necessary as a treatment of myopia.


BCBSMT considers implantation of intrastromal corneal ring segments experimental, investigational and unproven for all other conditions.

Policy Guidelines

Any pre and post-operative evaluations and/or measurement (echography, keratometry, pachometry, etc.) performed in conjunction with ineligible procedures should be denied.


Approval by the U.S. Food and Drug Administration (FDA) for the INTACS device was based on results of a multi-institutional study involving 361 subjects with mild myopia.  Subsequently, the two-year results of this study were published in the peer- reviewed literature.  These data suggest that the intrastromal rings predictably and effectively reduced or eliminate mild myopia (-1.00 to -3.00 diopter) and that the refractive effect was stable over time.  However, mild myopia is effectively treated with either spectacles or contact lenses.  Therefore, this application of INTACS is considered not medically necessary.  

The published data regarding INTACS for keratoconus consisted of single institution case series, with the largest case series including 74 subjects. The data available at this time were considered inadequate to permit scientific conclusions, due to the limited follow-up of one year.  Longer-term outcomes, and the key outcome of whether or not the use of the inserts will significantly delay or obviate the need for a corneal transplant, could not be evaluated.  For example, Boxer Wachler and colleagues reported on the outcomes in 74 eyes of 50 subjects with a mean follow-up of nine months.  A total of 45% gained at least two lines of best spectacle corrected visual acuity (BSCVA), 51% of patients had no change in vision, and 4% lost BSCVA.  Siganos and colleagues studied 33 eyes in 26 patients at a mean follow-up of 11.3 months.  In this study, 25 eyes recorded a 1- to 6-line gain in BSCVA, while four eyes remained unchanged and four eyes experienced a loss.  Colin and colleagues reported the one-year results in a series of 10 patients.  The mean values for BSCVA improved progressively over time, and at the 12-month follow-up, average visual acuity was two lines better than baseline.

From the published studies, a number of findings could be summarized:

  • A substantial proportion of patients with keratoconus treated with this system have improved vision.  Several studies report improvements (in uncorrected or corrected visual acuity) in 75% to 80% of patients in whom changes in 2–3 lines of corrected or uncorrected visual acuity were considered success.  One study reported improvement in just 42% (25/58); this study required an uncorrected visual acuity of 20/40 or better.
  • About 10% of patients (6 of 58) required a second procedure because of an unsatisfactory initial result.  Also, another study reported removal of 7 of 57 (12%) devices because of unsatisfactory results.
  • Complications do occur.  In one study, 6 of 20 eyes had “significant” postoperative problems with regards to thinning and ring exposure, and a dense corneal infiltrate developed in one patient at seven months.
  • There is limited published information about durability beyond 12 months.  In one report of 13 eyes followed up to 36 months, best corrected visual acuity remained stable and keratometric measurements increased by 36 months but did not reach pretreatment levels.
  • Studies also note that the procedure works best in those with mild to moderate disease compared to those with severe disease.
  • Alternative approaches (laser) are being used to place this type of ring.

In 2007, Colin and Malet reported two-year follow-up from a prospective, single-center European study in 100 eyes with keratoconus (82 consecutive patients) and INTACS implantation.  Patients had been referred for a penetrating keratoplasty procedure due to contact lens intolerance for correction of myopia and irregular astigmatism.  INTACS inserts were removed from four eyes (4%) due to poor visual outcome or extrusion, and 14 eyes were lost to follow-up.  Of the 82 remaining eyes (68 patients), both corrected and uncorrected visual acuity remained relatively stable between one- and two-years follow-up.  Central corneal thickness decreased from 478 microns pre-operatively to 434 microns at one year and 421 microns at two years.  The authors note that this finding may have resulted from slight stretching of the corneal tissue by the segments rather than a disease-related progressive thinning of the cornea.

Histopathologic examination of eight eyes that underwent penetrating keratoplasty after removal of INTACS inserts revealed keratocyte apoptosis.  The authors noted that further study is needed to determine whether INTACS accelerate corneal thinning and progression of keratoconus. Another study from 2007 reported five-year follow-up on 28 patients (36 eyes) who had initially participated in a clinical trial for safety and efficacy of INTACS implantation in patients with keratoconus.  In five patients (seven eyes), the INTACS segments were removed due to patient dissatisfaction.  An additional eight patients (12 eyes) were unable to attend follow-up appointments.  Five-year follow-up was reported for the remaining 17 eyes (59%).  Refractive stability was obtained at the six-month follow-up (spherical equivalent error at baseline -5.54 to -2.68 at six months) and remained stable throughout the five-year follow-up (-3.02).  With the exception of one eye that had a decrease of three lines, the best-corrected visual acuity was maintained to the pre-INTACS level.  Keratometric values showed a mean reduction of 1.57 diopters (49.59 to 48.02 diopters).

A small case series from Europe identified nine patients that received intrastromal ring segments (Kerarings) for high astigmatism (> 4 diopters) after penetrating keratoplasty.  Mean keratometry decreased 4.17 diopters (from 46.28 to 42.11).  Of the nine patients, one reported night halos and two had the implant removed due to compulsive eye rubbing and vascularization in the stromal tunnel.  The authors noted that in patients with a corneal transplant with a diameter of 7.5 mm or smaller, INTACS should not be used because the segments would be close to the graft-host junction.

Pellucid Marginal Degeneration

In 2009, Pinero and colleagues published a European multicenter retrospective analysis of 21 consecutive eyes (15 patients) with intrastromal corneal ring implantation (three INTACS and 18 KeraRings) for pellucid marginal degeneration that had reduced best-corrected visual acuity and/or contact lens intolerance or dissatisfaction.  At six months after surgery, uncorrected visual acuity had not changed, 17% of eyes lost lines of best-corrected visual acuity and 44% of eyes gained > 2 lines of best-corrected visual acuity.  Ring explantation was performed in four eyes (19%) due to visual deterioration during the follow-up.  Mean keratometry decreased 1.76 diopters, from 44.95 diopters to 43.19 diopters at six-months postoperatively.

Adverse events

Updated literature searches, the most recent performed in August 2010, have identified a number of case reports of adverse events following implantation of intrastromal corneal ring segments, including persistent pain, extrusion, traumatic shattering, bacterial keratitis, fungal keratitis, corneal edema, deep corneal vascularization, Descemet membrane’s detachment, and alterations of extracellular matrix components and proteinases.  In a multicenter series of 251 intrastromal corneal ring segment implantations, 58 eyes of 47 patients (23%) had the devices explanted.  The main cause was found to be extrusion (48%), followed by poor refractive outcome (38%), keratitis (7%), and corneal melting and perforation (7%).  The time from implantation to explanation ranged from 0.1 to 82 months.

Clinical Trials

A search of in August 2010 identified two randomized trials on the treatment of keratoconus with combined use of intrastromal corneal ring segments and collagen cross-linking.  A phase II/III randomized trial (NCT01081561) will compare corneal collagen cross-linking in eyes with INTACS compared to eyes without INTACS.  The study has an estimated enrollment of 400 subjects with an estimated completion date for the primary outcome measure in 2015.  Another phase III trial (NCT01112072) will randomize subjects to receive collagen cross linking immediately after, or three months after INTACS implantation.  Estimated enrollment is 160 subjects with an estimated completion date for the primary outcome measure in April 2011.


Clinical input strongly supports the use of INTACS in a select group of patients with advanced keratoconus whose only other option for restoration of visual function is the more invasive penetrating keratoplasty.  Although questions remain regarding the impact of this procedure on long-term health outcomes, the risk of adverse events is decreased in comparison with the existing alternative (corneal transplant), and there is a potential (as yet unproven) to delay the need for the more invasive procedure.  Therefore, use of INTACS may be considered medically necessary in patients who meet the FDA-HDE criteria for use of this device.

The United Kingdom’s National Institute for Health and Clinical Excellence (NICE) issued guidance in 2007 on corneal implants for keratoconus.  The guidance, based on nine case series, one non- randomized controlled trial and specialist advisors’ opinion concluded that “current evidence on the safety and efficacy of corneal implants for keratoconus appears adequate to support the use of this procedure provided that normal arrangements are in place for consent, audit and clinical governance.”

There is insufficient evidence to evaluate health outcomes in patients with pellucid marginal deterioration.  Therefore, INTACS in this population are considered investigational.


Disclaimer for coding information on Medical Policies           

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy. They may not be all-inclusive.           

The presence or absence of procedure, service, supply, device or diagnosis codes in a Medical Policy document has no relevance for determination of benefit coverage for members or reimbursement for providers. Only the written coverage position in a medical policy should be used for such determinations.           

Benefit coverage determinations based on written Medical Policy coverage positions must include review of the member’s benefit contract or Summary Plan Description (SPD) for defined coverage vs. non-coverage, benefit exclusions, and benefit limitations such as dollar or duration caps. 

ICD-9 Codes
11.79, 367.1, 371.60 – 371.62; Investigational for all other diagnoses.
ICD-10 Codes
H18.601-H18.629, 08U80JZ, 08U83JZ, 08U8XJZ, 08U90JZ, 08U93JZ, 08U9XJZ
Procedural Codes: 0099T
  1. U.S. Food and Drug Administration. PMA - Premarket Approval. (1999) <>. (accessed October 2010).
  2. Schanzlin, D.J., Abbott, R.L., et al.  Two-year outcomes of intrastromal corneal ring segments for the correction of myopia. Ophthalmology (2001) 108(9):1688-94.
  3. Colin, J., Cochener, B., et al.  INTACS inserts for treating keratoconus: one-year results. Ophthalmology (2001) 108(8):1409-14.
  4. Boxer Wachler, B.S., Christie, J.P., et al.  Intacs for keratoconus. Ophthalmology (2003) 110(5):1031-40.
  5. Siganos, C.S., Kymionis, G.D., et al.  Management of keratoconus with Intacs. American Journal of Ophthalmology (2003) 135(1):64-70.
  6. Levinger, S., and R. Pokroy.  Keratoconus managed with intacs: one-year results. Archives of Ophthalmology (2005) 123(10):1308-14.
  7. Alio, J.L., Shabayek, M.H., et al.  Analysis of results related to good and bad outcomes of Intacs implantation for keratoconus correction.  Journal of Cataract Refractive Surgery (2006) 32(5):756-61.
  8. Colin, J.  European clinical evaluation: use of Intacs for the treatment of keratoconus.  Journal of Cataract Refractive Surgery (2006) 32(5):747-55.
  9. Kanellopoulos, A.J., Pe, L.H., et al.  Modified intracorneal ring segment implantations (INTACS) for the management of moderate to advanced keratoconus: efficacy and complications. Cornea (2006) 25(1):29-33.
  10. Alio, J.L., Shabayek, M.H., et al.  Intracorneal ring segments for keratoconus correction: long-term follow-up.  Journal of Cataract Refractive Surgery (2006) 32(6):978-85.
  11. Rabinowitz, Y.S., Li, X., et al.  INTACS inserts using the femtosecond laser compared to the mechanical spreader in the treatment of keratoconus. Journal Refractive Surgery (2006) 22(8):764-71.
  12. Colin, J., and F.J. Malet.  Intacs for the correction of keratoconus: two-year follow-up. Journal of Cataract and Refractive Surgery (2007) 33(1):69-74.
  13. Samimi, S., Leger, F., et al.  Histopathological findings after intracorneal ring segment implantation in keratoconic human corneas.  Journal of Cataract Refractive Surgery (2007) 33(2):247-53.
  14. Kymionis, G.D., Siganos, C.S., et al.  Long-term follow-up of Intacs in keratoconus.  American Journal of Ophthalmology (2007) 143(2):236-44.
  15. Arriola-Villalobos, P., Diaz-Valle, D., et al.  Intrastromal corneal ring segment implantation for high astigmatism after penetrating keratoplasty.  Journal of Cataract and Refractive Surgery (2009) 35(11):1878-84.
  16. Pinero, D.P., Alio, J.L., et al.  Refractive and corneal aberrometric changes after intracorneal ring implantation in corneas with pellucid marginal degeneration. Ophthalmology (2009) 116(9):1656-64.
  17. Ferrer, C., Alio, J.L., et al.  Causes of intrastromal corneal ring segment explantation: clinicopathologic correlation analysis.  Journal of Cataract and Refractive Surgery (2010) 36(6):970-7.
  18. National Institute for Health and Clinical Excellence (NICE).  Guidance on corneal implants for keratoconus.  (2007) . (accessed 2010 October).
  19. Implantation of Intrastromal Corneal Ring Segments.  Chicago, Illinois:  Blue Cross Blue Shield Association Medical Policy Reference Manual (2010 October) Surgery 9.03.14.
December 2010  Policy statement changed to include medically necessary criteria for coverage. Previously considered not medically necessary. Rationale and references updated. 
November 2012  Policy updated with literature review through July 2012; Rationale section revised; references 6, 8, and 17 added; some references removed; policy statements unchanged. 
August 2013 Policy formatting and language revised.  Policy statement unchanged.
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Implantation of Intrastromal Corneal Ring Segments