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«PacifiCare’s medical management guidelines represent the recommendation of the PacifiCare Medical Management Guideline (MMG) committee. They are ...»

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- keratoconus Laser In Situ Keratomileusis (LASIK), Laser-Assisted Subepithelial Keratectomy (LASEK), and Photorefractive Keratectomy (PRK) When used according to U.S. Food and Drug Administration (FDA) indications, ophthalmologic excimer laser surgery with laser in situ keratomileusis (LASIK), laser-assisted subepithelial keratectomy (LASEK), or photorefractive keratectomy (PRK) is proven for the treatment of surgically induced astigmatism or surgically induced anisometropia with all of the

following:

- Inability to wear eyeglasses or contact lenses after surgery due to anisometropia (eyes having unequal refractive power) and/or high astigmatism.

- Documented attempts to correct the surgical error with historical means of refraction and/or contact lens fitting

- 2.5 diopter or more increase in astigmatism and/or anisometropia from the pre to the postoperative state.

- Functional disability due to the increased astigmatism and a reasonable expectation that the laser will improve the patient's function.

Computerized Corneal Topography-Guided Customized Excimer Laser Ablation Computerized corneal topography-guided customized excimer laser ablation is unproven for the correction of decentered ablation. Insufficient evidence exists to support the use of

Excimer Laser- Commercial Medical Management Guideline

computerized corneal topography (CCT)-guided customized ablation with excimer laser.

Conclusions regarding topography-guided laser ablation are limited by the small number of studies with very small sample sizes and the lack of objective methods for assessing patients' experience of higher order aberrations. Additional studies are needed to establish efficacy and safety, and to define patient selection criteria.

–  –  –

Regulatory Requirements U.S. Food and Drug Administration (FDA): Excimer laser systems for ophthalmic surgery are regulated by the FDA as Class III devices, a classification that indicates that these devices are subject to the most extensive regulations enforced by the FDA. Several manufacturers have completed the FDA Premarket Approval (PMA) process for excimer lasers and related devices. See the following Web sites for more information: http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfPMA/pma.cfm.

(Use product code LZS: excimer laser system) Accessed March 2009.

http://www.fda.gov/CDRH/LASIK/lasers.htm. Accessed March 2009.

VISX Technology was granted a Humanitarian Use Device (HUD) designation for the Custom Contoured Ablation Pattern (C-CAP) Method™ on December 19, 2001. To be regarded a HUD, a device must be intended to benefit patients by treating or diagnosing a disease or condition that affects fewer than 4000 individuals in the United States per year. C-CAP is approved for use in the treatment of asymmetrical ablation patterns from previous laser refractive surgery caused by decentration of the treatment as viewed on the Humphrey® Atlas™ (Carl Zeiss Meditec) topography unit and treated with the STAR S3 ActiveTrak™ Excimer Laser System (VISX Technology) in

patients who meet the following criteria:

- exhibit symptomatology supportive of visual defect: reduced best spectacle-corrected visual acuity, debilitating glare, monocular diplopia (double vision), and/or debilitating halos; and,

- preoperatively have at least a 6-difference on the elevation topography, from the lowest point to the highest point, over a 6.5-mm diameter or over the patient's pupil diameter as measured by the Zeiss

Humphrey topographer, whichever is larger. See the following Web site for more information:

http://www.fda.gov/cdrh/ode/H000002sum.html. Accessed March 2009.

Research Evidence Background Surgical techniques involving instruments such as scalpels, spatulas, or microkeratomes have been used for correction of refractive errors and treatment of some types of corneal disorders. For most Excimer Laser- Commercial Medical Management Guideline patients who have refractive disorders, normal vision can be obtained with a corrective aid such as eyeglasses or contact lenses.

A number of corneal disorders can cause lesions on the eye or in a specific layer of corneal tissue.

Recurrent corneal erosion can arise from a number of causes including ocular trauma; contact lensinduced keratopathy; anterior basement membrane dystrophy, also known as map-dot-fingerprint dystrophy; bullous keratopathy; Reis-Buckler's dystrophy, an epithelial detachment and development of subepithelial opacities; and granular and lattice dystrophies, characterized by noninflammatory development of corneal opacities. Scars on the cornea can result from disorders such as ocular trauma or ulceration, band keratopathy, pterygia, and Salzmann's degeneration (formation of nodules containing clumped collagen fibrils). Two other corneal disorders that can arise are keratoconus, corneal thinning that results in corneal surface distortion, and Fuchs' dystrophy, corneal edema that can lead to an accumulation of subepithelial scar tissue. Treatment of corneal scars, recurrent corneal erosions, and other corneal disorders depends on the specific disorder but may include conservative therapies such as topical lubricants, bandage soft contact lenses, and for band keratopathy, agents to chelate calcium. If treatments such as these are unsuccessful, surgical procedures such as superficial keratectomy, epithelial debridement, stromal puncture, or a corneal transplantation procedure such as penetrating keratoplasty may be required.





Excimer lasers that use ultraviolet light are now being utilized as a nonmechanical means of cutting and ablating ocular tissue in the correction of refractive errors and corneal disorders. For corneal disorders that cause corneal erosion and scarring, phototherapeutic keratectomy (PTK) is used to cut through the epithelium or ablate specific corneal lesions. PTK uses an excimer laser, but does not change the refractive state of the eyes.

For refractive disorders such as astigmatism and anisometropia (eyes have unequal refractive power), the laser-based treatments that have been developed to reshape the cornea include laser in situ keratomileusis (LASIK), laser-assisted subepithelial keratectomy (LASEK), and photorefractive keratectomy (PRK). Although LASIK, LASEK, and PRK involve removal of the corneal epithelium and laser ablation of subepithelial tissue, they differ in that the epithelium is reattached after LASIK and LASEK. LASEK uses an ethanol solution and special instruments for removal of the corneal epithelium.

According to proponents of excimer laser surgery, an advantage of the laser is that it causes less deformation of ocular tissue than do mechanical instruments.

Customized excimer laser ablation based on computerized corneal topography (CCT) is used in retreatment of visual disorders, such as decentered ablation. Decentered ablation, also referred to as eccentric or off-center ablation, occurs when the center of a surgical ablation (the flat zone) does not correspond to the center of the optical axis (center of entrance to the pupil). Visual problems associated with decentered ablations, a type of irregular astigmatism, are halos, glare, or double

Excimer Laser- Commercial Medical Management Guideline

vision. Symptoms tend to be worse at night and whenever lighting is reduced. Laser surgery is a common cause of decentered ablation. Correction of decentered ablation consists of balancing the decentration and may be attempted by either laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK). Customized ablation based on computerized corneal topography (CCT) seeks to improve predictability and is used to generate a map of the corneal surface for planning the corrective tissue removal. The computerized plan is then programmed into the excimer laser device.

Research Evidence Excimer Laser Phototherapeutic Keratectomy (PTK) Ohman and Fagerholm (1998) conducted a randomized study that evaluated excimer laser treatment as an adjunct to manual epithelial debridement for corneal erosions. Excimer laser therapy was associated with a statistically significant decrease in recurrence of erosions, compared with a control group that underwent manual epithelial debridement alone. Although this study provided 12 months of follow-up, it had certain limitations, including a small sample size (n=56) and incomplete followup for 9% of patients.

Several uncontrolled studies evaluated PTK for corneal dystrophy. Pogorelov et al. (2006) assessed PTK for corneal map-dot-fingerprint dystrophy in 15 eyes of 11 patients that resulted in complete epithelial closure in an average of 3.5 days. Best corrected visual acuity increased from 0.7 preoperatively to 0.9 postoperatively. Das et al. (2005b) evaluated 62 eyes of 40 patients with granular and lattice dystrophy who underwent PTK. Best spectacle-corrected visual acuity improved in 79% and 62% of eyes with granular and lattice dystrophy, respectively. The investigators concluded that PTK may be tried in patients with granular and lattice corneal dystrophy before undergoing a more invasive procedure. Das et al. (2005c) found that 6 of 19 eyes with lattice dystrophy experienced delayed healing after PTK.

A prospective study assessed 31 consecutive PTK procedures for superficial corneal scars. After a mean follow-up of 2 years, best corrected visual acuity increased preoperatively from 0.3+/-0.2 to 0.5+/-0.3 (increase 87%, decrease 3%, no change 10%). Corneal surface topography regularized significantly. (Hafner et al., 2004) A retrospective study included 22 eyes in 14 patients who underwent phototherapeutic keratectomy (PTK) for treatment of Salzmann's nodular degeneration. Visual acuity improved in 86% of the eyes after PTK. The investigators concluded that PTK is safe and effective for treatment of Salzmann's nodular degeneration. (Das et al., 2005a) Two case series evaluated excimer laser therapy for bullous keratopathy. Both of these studies were small (n=8; n=13 eyes) and both reported that laser therapy was beneficial. Over a mean follow-up period of 14 months, Thomann et al. (1995) found that laser treatment relieved pain for all patients, although 38% of patients required 2 sessions of laser treatment to obtain adequate pain relief.

Likewise, Lin et al. (2001) reported that all patients experienced pain relief over a mean of 11 months follow-up. However, these studies were small and uncontrolled.

Excimer Laser- Commercial Medical Management Guideline

Elsahn et al. (2009) reported the outcomes of 15 contact lens-intolerant patients with keratoconus (KCN) with subepithelial nodules treated with excimer laser phototherapeutic keratectomy (PTK).

Preoperative and postoperative visual acuity and method of correction, surgical treatment, epithelial healing, complications, and KCN nodule recurrence were analyzed. Mean follow-up time was 23.1 months. Three patients had a recurrence of the KCN nodule at 3, 8, and 23 months postoperatively.

The investigators concluded that PTK effectively removed KCN nodules without recurrences in most patients and can be a successful modality to improve contact lens tolerance and delay or avoid more invasive surgery.

Laser In Situ Keratomileusis (LASIK), Laser-Assisted Subepithelial Keratectomy (LASEK), or Photorefractive Keratectomy (PRK) Kato et al. (2008) examined 779 eyes in 402 patients with myopia or myopic astigmatism who underwent LASIK to correct their refractive errors and received regular postoperative assessments for 5 years. Preoperative uncorrected visual acuity (UCVA) of 1.27 improved to -0.03 at 1 day after surgery and -0.08 at 1 month and revealed minimal but significant decreases thereafter. The investigators concluded that LASIK surgery is an effective and safe procedure for correcting myopia/myopic astigmatism as long as inclusion and exclusion criteria are strictly respected.

Minimal regression occurred during the 5-year investigative period.

A randomized study (n=179) evaluated mechanical trephination versus excimer laser trephination as part of a penetrating keratoplasty (PK) procedure that included corneal transplantation. This study included patients with keratoconus and Fuchs' dystrophy and was described in 6 articles. The study found that excimer laser trephination provided statistically significant improvements in bestcorrected visual acuity, astigmatism, and corneal surface regularity. Although the randomized trial of excimer laser trephination involved a mean of 37 months of follow-up, it does have shortcomings, including failure to report outcomes separately for patients with keratoconus and Fuchs' dystrophy, and performance of all procedures by a single surgeon who may have a level of expertise that cannot be readily duplicated by other practitioners. (Seitz, et al., 1999; Kuchle et al, 1998; Langenbucher et al., 1998; Behrens et al., 2000; Seitz et al., 2001; Seitz et al., 2002) Hardten et al. (2004) evaluated the long-term safety and effectiveness of laser-assisted in situ keratomileusis (LASIK) in the treatment of refractive errors following penetrating keratoplasty. A retrospective review was done in 57 eyes of 48 patients with anisometropia or high astigmatism who were unable to wear glasses or a contact lens after penetrating keratoplasty and who underwent LASIK for visual rehabilitation. The mean follow-up after the LASIK was 21.4 +/- 14.2 months.

Mean preoperative spherical equivalent (SE) was -4.19 +/- 3.38 diopters (D). Mean preoperative astigmatism was 4.67 +/- 2.18 D. Preoperative best spectacle-corrected visual acuity (BCVA) was 20/40 or better in 42 eyes (74%). At 2 years the mean SE was -0.61 +/- 1.81 D and mean astigmatism was 1.94 +/- 1.35 D for the 28 eyes with follow-up. UCVA was 20/40 or better in 12 eyes (43%), and BCVA was 20/40 or better in 24 eyes (86%) at 2 years. A gain in BCVA of one line or more was

Excimer Laser- Commercial Medical Management Guideline

seen in eight eyes (29%). Two eyes (7%) had loss of two or more lines of BCVA at 2 years. Nine eyes (16%) developed epithelial ingrowth. Five eyes (9%) in this series had repeat corneal transplants. The investigators concluded that LASIK is effective for reducing ametropia after penetrating keratoplasty. Proper patient counseling is necessary because the results of LASIK after penetrating keratoplasty are not as good as, and complications are more frequent than, in eyes with naturally occurring myopia and astigmatism.



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