1. Aetna considers computerized corneal topography medically necessary for any of the following conditions:

   • Central corneal ulcer; or
   • Corneal dystrophy, bullous keratopathy and complications of transplanted cornea; or
   • Diagnosing and monitoring disease progression in keratoconus or Terrien's marginal degeneration; or 
   • Difficult fitting of contact lens (see CPB 0126 - Contact Lenses and Eyeglasses)*; or 
   • Post-traumatic corneal scarring; or
   • Pre- and post-penetrating keratoplasty and post kerato-refractive surgery for irregular astigmatism (subject to medical necessity criteria for these procedures - see CPB 0023 - Corneal Remodeling); or 
   • Pterygium or pseudo pterygium.

   * Generally, 1 testing for each eye is sufficient for fitting, unless there is some reason for repeat testing conducted in the medical record, such as a change in the member's condition from the prior examination.  Repeat testing to monitor disease progression in keratoconus or Terrien's marginal degeneration may be necessary over time.

2. Note: Aetna does not cover corneal topography if it is performed pre- or post-operatively in relation to a non-covered procedure (i.e., refractive eye surgery).  Most Aetna benefit plans exclude coverage of refractive surgery.  Please check benefit plan descriptions for details.

3. Aetna considers corneal topography experimental and investigational if it is performed as part of pre-operative assessment of members with cataracts (see CPB 0508 - Cataract Removal Surgery).

4. Aetna considers corneal topography experimental and investigational for the management of members with the following indications (not an all-inclusive list) because corneal topography has not been shown to alter the clinical management of these conditions such that clinical outcomes are improved.

• Acanthomoeba keratitis
• Epithelial ingrowth following laser in situ keratomileusis (LASIK)
• Interstitial keratitis
• Lens subluxation (e.g., in Marfan syndrome)
• Limbal dermoids
• Nodular degeneration of the cornea (e.g., Salzmann's corneal degeneration)
• Ocular graft-versus-host disease
• Open-angle glaucoma
• Superficial punctate keratopathy.

Computerized corneal topography (also known as computer assisted corneal topography, computer assisted keratography, or videokeratography) is a computer- assisted diagnostic technique in which a special instrument projects a series of light rings on the cornea, creating a color-coded map of the corneal surface as well as a cross-section profile.  This test is used for the detection of subtle corneal surface irregularities and astigmatism as an alternative to manual keratometry.

The American Academy of Ophthalmology’s guidelines on “Primary open-angle glaucoma” (AAO, 2010) mentioned no role for corneal topography in the management of patients with open-angle glaucoma.

Choi and Kim (2012) examined the longitudinal changes in corneal topographic indices over time in patients with mild keratoconus (KC) and determined predictive factors for the increase in corneal curvature.  These investigators retrospectively reviewed the data of 94 eyes of patients with mild KC who had undergone computerized video-keratography (Orbscan IIz; Bausch & Lomb Surgical, Rochester, NY) at least twice at an interval of greater than or equal to 1 year.  Patients with an increase of greater than or equal to 1.50 diopters (D) in the central keratometry (K) were placed in the progression group, and the others were placed in the non-progression group.  In each group, the quantitative topographic parameters were compared and tested as predictive factors for KC progression.  Additionally, corneal astigmatic changes were evaluated by means of vector analysis.  In total, 94 eyes of 85 patients were included -- 25 of 94 (26.5 %) eyes showed progression of the central K greater than or equal to 1.50 D; progression took 3.5 years on average.  Median time to progression by Kaplan-Meier analysis was 12 years.  Significant predictors for KC progression were as follows: highest point on the anterior elevation from the anterior best-fit sphere (BFS), greater than or equal to 0.04 mm; irregularity index at 3 mm, greater than or equal to 6.5 D; irregularity index at 5 mm, greater than or equal to 6.0 D; thinnest pachymetry, less than 350 μm at baseline examination; yearly change rate of anterior BFS, greater than or equal to 0.1 D/year; central K, greater than or equal to 0.1 D/year; simulated K in maximum, greater than or equal to 0.15 D/year; simulated K in minimum, greater than or equal to 0.2 D/year; and anterior chamber depth, greater than or equal to 0.0 mm/year.  The dominant with-the-rule pattern of astigmatism at the baseline examination was changed to an oblique pattern of astigmatism at the last examination.  The authors concluded that mild KC tended to be progressive in approximately 25 % of patients, and progression lasted 3.5 years on average.  They stated that longitudinal changes in the corneal topography quantitative indices can be used as predictors of KC progression.