Corneal Pachymetry

Number: 0681

Policy

  1. Aetna considers ultrasound corneal pachymetry medically necessary for the following indications:

    1. Anatomical narrow angles; or
    2. Bullous keratopathy; or
    3. Corneal edema; or
    4. Corneal refractive surgery (pre- and post-operative evaluation)Footnotes for aetna coverage plans*; or
    5. Corneal transplant (penetrating keratoplasty) (pre- and post-operative evaluation); or
    6. Evaluation of complications of corneal refractive surgery (once); or
    7. Evaluation of corneal rejection post penetrating keratoplasty; or
    8. Fuchs' endothelial dystrophy; or
    9. Persons with glaucoma or glaucoma suspects (testing is considered medically necessary once per lifetime); or
    10. Posterior polymorphous dystrophy

    Aetna considers repeat ultrasound corneal pachymetry for corneal diseases and injuries (indications D through I) not medically necessary if performed more frequently than once every 6 months.

  2. Aetna considers corneal pachymetry to be of no proven value in the work-up of persons prior to cataract surgery unless corneal disease is documented. See CPB 0508 - Cataract Removal Surgery.

  3. Aetna considers corneal pachymetry experimental and investigational for the following indications (not an all-inclusive list) because its effectiveness for these indications has not been established.

    • As a screening test for glaucoma for persons without signs or symptoms of glaucoma or elevated intra-ocular pressure
    • Diagnosis of Marfan syndrome
    • Diagnosis or monitoring of Terrien's corneal marginal degeneration
    • Evaluation of persons with keratoconus
    • Monitoring of persons on hydroxychloroquine (Plaquenil)

Footnotes*Note: Most Aetna benefit plans exclude coverage of refractive surgery.  Please check benefit plan descriptions for details.  Corneal pachymetry for evaluation of persons undergoing corneal refractive surgery is excluded from coverage under plans with these provisions.

Note: For purposes of this policy, only the ultrasound method of corneal pachymetry is considered.

Background

Corneal pachymetry is a non-invasive ultrasonic technique for measuring corneal thickness, and has been used primarily in the evaluation of persons with corneal diseases and in the assessment of persons at risk for glaucoma.  Ultrasonic corneal pachymetry is performed by placing an ultrasonic probe on the central cornea, after the cornea has been anesthetized with a topical anesthetic.  A technician can operate the pachymeter and it normally takes less than 30 seconds per eye to complete measurements.

The Ocular Hypertension Treatment Study (Kass et al, 2002; Gordon et al, 2002), a prospective randomized controlled clinical trial of glaucoma treatment in persons with elevated intra-ocular pressure (IOP) greater than or equal to 24 mm Hg, found central corneal thickness a statistically significant predictor of development of glaucoma.  Corneal thickness was measured only after the study was initiated, and was not used to guide therapy.  For the enrolled patients, the Ocular Hypertension Treatment Study results identified central corneal thickness less than 556 microns and a vertical or horizontal cup to disc ratio greater than 0.4 (vertical or horizontal) as risk factors for glaucomatous damage.

The Ocular Hypertension Treatment Study (Kass et al, 2002: Gordon et al, 2002) results suggested that IOP measurements need to be adjusted for abnormally thick or thin corneas.  The target IOP is lower for a thin cornea and higher for a thick cornea.  Eyes with thick corneas have a true IOP that is lower than the measured IOP.  Conversely, eyes with thin corneas have a true IOP that is greater than the measured IOP.  Thus, individuals with thicker corneas may be mis-classified as having ocular hypertension.

The Ocular Hypertension Treatment Study is the first to establish corneal thickness as a risk factor for glaucoma.  However, the conclusions of OHTS are limited to persons with ocular hypertension (greater than 24 mm Hg), and do not establish the value of corneal pachymetry for screening persons without ocular hypertension.  In addition, there are no prospective clinical outcome studies demonstrating the clinical utility of corneal pachymetry in selecting patients for therapy, for guiding therapy and improving clinical outcomes.

Based on the results of this study, the American Academy of Ophthalmology Preferred Practice Pattern on Evaluation of the Glaucoma Suspect (2005) recommended measurement of corneal thickness with electronic pachymetry in evaluating the glaucoma suspect.

Repeat measurements of corneal thickness for glaucoma are not necessary unless the patient has corneal diseases or surgery affecting corneal thickness.  Changes in corneal thickness with age are minimal in adulthood, with estimated changes of 0.006 to 0.015 mm per decade (Doughty and Zaman, 2000).

Corneal pachymetry may be useful in assessing candidates for penetrating keratoplasty (corneal transplant), and assessing graft failure and the need for regrafting in corneal transplant recipients by aiding in the early diagnosis and treatment of graft rejection.  Corneal pachymetry may also be useful in assessing the response to treatment of corneal transplant rejection.  Corneal pachymetry has also been used to assess progression of disease in patients with certain corneal dystrophies and degenerative diseases.

Although keratoconus is associated with corneal thinning, available evidence indicates that ultrasonic corneal pachymetry is not as accurate as videokeratography in diagnosing keratoconus.  Rabinowitz et al (1998) compared the accuracy of ultrasonic pachymetry measurements and videokeratography-derived indices in distinguishing keratoconus patients from those with normal eyes.  The investigators measured corneal thickness by ultrasonic pachymetry at the center and inferior margins of the pupil of 142 normal and 99 keratoconus patients.  The corneal surface topography of patients was studied with videokeratography.  The investigators reported that the range of corneal thickness in normal and keratoconic eyes overlapped considerably.  The investigators reported that videokeratography indices provided a 97.5 % correct classification rate and pachymetry data, an 86.0 % rate (p < 0.01).  The investigators concluded that keratoconus is more accurately distinguished from the normal population by videokeratography-derived indices than by ultrasonic pachymetry measurements.  The investigators posited that this may be due to the large variation in corneal thickness in the normal population or the inability of ultrasonic pachymetry to accurately detect the location of corneal thinning in keratoconus by measuring standard points on the cornea.  The investigators concluded that pachymetry should not be relied on to exclude or diagnose keratoconus because the false-negative and false-positive rates are unacceptably higher than those obtained by videokeratography.

Sultan and colleagues (2002) examined corneal thickness, curvature, and morphology with the Orbscan Topography System I in patients with Marfan syndrome (MFS) and studied MFS with in-vivo confocal microscopy.  This prospective, clinical, comparative case series included 60 eyes of 31 patients with MFS and 32 eyes of 17 control subjects.  First, biomicroscopic examination was conducted to search for ectopia lentis.  Then, mean keratometry and ocular refractive power were calculated by the autokeratorefractometer.  In each group, the Orbscan System I mean (and mean simulated) keratometry and pachymetric measurements (at the central location and at 8 mid-peripheral locations) were obtained and compared, and correlations were established.  In-vivo confocal microscopy was performed to evaluate tissue morphology and Z-scan analysis of 14 thin MFS corneas compared with 14 control corneas.  A significant decrease (ANOVA, p < 0.0001) of mean simulated keratometry measurement appeared in the MFS group (sim K, 40.8 +/- 1.4 D) compared with the control group (42.9 +/- 1.1 D).  Pachymetry in the MFS group was significantly decreased (p < 0.0001) compared with that in the control group, in the center (respectively, 502 +/- 41.9 microm and 552 +/- 23.6 microm) and the 8 mid-peripheral locations.  Ectopia lentis was highly linked with mean keratometry and pachymetry (p < 0.0001).  Confocal microscopy performed on MFS-affected thin corneas confirmed the corneal thinning and showed an opaque stromal matrix, and Z-scan profiles were abnormal with increased stromal back scattering of light.  The authors concluded that MFS is known to be associated with a flattened cornea.  This study demonstrated an association with corneal thinning and described confocal microscopy findings in MFS.  While the finding of this study that used the Orbscan System (a slit-scanning light method) is interesting, there is currently a lack of evidence to support the use of ultrasound pachymetry in the diagnosis of MFS.

Table: CPT Codes / HCPCS Codes / ICD-10 Codes
Code Code Description

Information in the [brackets] below has been added for clarification purposes.   Codes requiring a 7th character are represented by "+":

CPT codes covered if selection criteria are met:
76514 Ophthalmic ultrasound, diagnostic; corneal pachymetry, unilateral or bilateral (determination of corneal thickness)

CPT codes not covered for indications listed in the CPB:
66830 - 66984 Removal of cataract

Other CPT codes related to the CPB:
65710 - 65775 Keratoplasty
65820 Goniotomy
92020 Gonioscopy (separate procedure)
92100 - 92130 Serial tonometry and tonography

Other HCPCS codes related to the CPB:
G0117 Glaucoma screening for high risk patients furnished by an optometrist or ophthalmologist
G0118 Glaucoma screening for high risk patients furnished under the direct supervision of an optometrist or ophthalmologist
S0800 Laser in situ keratomileusis (LASIK)
S0810 Photorefractive keratectomy (PRK)
S0812 Phototherapeutic keratectomy (PTK)

ICD-10 codes covered if selection criteria are met:
H18.10 - H18.239 Corneal edema and bullous keratopathy
H18.51 Endothelial corneal dystrophy [Fuchs' only]
H18.59 Other hereditary corneal dystrophies [posterior polymorphous corneal dystrophy]
H40.001 - H40.33x4
H40.50x0 - H42		 Glaucoma
H40.40x0 - H40.43x4 Glaucoma secondary to eye inflammation
H47.231 - H47.239 Glaucomatous optic atrophy [cupping]
Q15.0 Congenital glaucoma [Buphthalmos]
T86.840 Corneal transplant rejection
Z94.7 Corneal transplant status

ICD-10 codes not covered for indications listed in the CPB [not all-inclusive]:
B50.0 - B54 Malaria
H18.461 - H18.469 Peripheral corneal degeneration [Terrien's corneal marginal degeneration]
H18.601 - H18.629 Keratoconus
H25.011 - H26.9
H28		 Age-related and other cataract
M05.40 - M06.9 Rheumatoid arthritis [not covered for monitoring plaquenil]
M32.0 - M32.0 Systemic lupus erythematosus (SLE) [not covered for monitoring plaquenil]
Q12.0 Congenital cataract
Q87.40 - Q87.43 Marfan's syndrome
T37.2x1+ - T37.2x4+ Poisoning by antimalarials and drugs acting on other blood protozoa
Z13.5 Encounter for screening for eye and ear disorders

The above policy is based on the following references:

  1. American Academy of Ophthalmology Refractive Management/Intervention Panel. Refractive errors and refractive surgery. Preferred Practice Pattern. San Francisco, CA: American Academy of Ophthalmology; 2007.
  2. Canadian Ophthalmological Society. Practice guidelines for refractive surgery. Policy Statements and Guidelines. Ottawa, ON: Canadian Ophthalmological Society; June 2000.
  3. American Academy of Ophthalmology Glaucoma Panel. Primary open-angle glaucoma suspect. Preferred Practice Pattern. San Francisco, CA: American Academy of Ophthalmology; 2005.
  4. American Academy of Ophthalmology Glaucoma Panel. Primary angle closure. Preferred Practice Pattern. San Francisco, CA: American Academy of Ophthalmology; 2005.
  5. American Academy of Ophthalmology Glaucoma Panel. Primary open-angle glaucoma. Preferred Practice Pattern. San Francisco, CA: American Academy of Ophthalmology; 2005.
  6. Palmberg P. Answers from the ocular hypertension treatment study. Archiv Ophthalmol. 2002;120 (6):829-830.
  7. Doughty MJ, Zaman ML. Human corneal thickness and its impact on intraocular pressure measures: A review and meta-analysis approach. Surv Ophthalmol. 2000;44(5):367-408.
  8. Whitacre MM, Stein RA, Hassanein K. The effect of corneal thickness on applanation tonometry. Am J Ophthalmol. 1993;115:592-596.
  9. Gordon MO, Beiser JA, Brandt JD, et al. The Ocular Hypertension Treatment Study: Baseline factors that predict the onset of primary open angle glaucoma. Arch Ophthalmol. 2002;120(6):714-719.
  10. Kass MA, Heuer DK, Higginbotham EJ, et al. The Ocular Hypertension Treatment Study: A randomized trial determines that topical ocular hypertensive medication delays or prevents the onset of primary open-angle glaucoma. Archiv Ophthalmol. 2002;120(6):701-713.
  11. Singh RP, Goldberg I, Graham SL, et al. Central corneal thickness, tonometry and ocular dimensions in glaucoma and ocular hypertension. J Glaucoma. 2001;10(3):206-210.
  12. Lee GA, Khaw PT, Ficker LA, Shah P. The corneal thickness and intraocular pressure story: Where are we now? Clin Experiment Ophthalmol. 2002;30(5):334-337.
  13. Bechmann M, Thiel MJ, Neubauer AS, et al. Central corneal thickness measurements with retinal optical coherence tomography device versus standard ultrasonic pachymetry. Cornea. 2001;20(1):50-54.
  14. Brandt JD, Beiser JA, Kass MA, et al. Central corneal thickness in the Ocular Hypertension Treatment Study (OHTS). Ophthalmology. 2001;108(10):1779-1788.
  15. Rainer G, Petternel V, Findl O, et al. Comparison of ultrasound pachymetry and partial coherence interferometry in the measurement of central corneal thickness. J Cataract Refract Surg. 2002;28(12):2142-2145.
  16. Reinstein DZ, Silverman RH, Raevsky T, et al. Arc-scanning very high-frequency digital ultrasound for 3D pachymetric mapping of the corneal epithelium and stroma in laser in situ keratomileusis. J Refract Surg. 2000;16(4):414-430.
  17. Giraldez Fernandez MJ, Diaz Rey A, Cervino A, Yerbra-Pimentel E. A comparison of two pachymetric systems: Slit-scanning and ultrasonic. CLAO J. 2002;28(4):221-223.
  18. Phillips LJ, Cakanac CJ, Eger MW, Lilly ME. Central corneal thickness and measured IOP: A clinical study. Optometry. 2003;74(4):218-225.
  19. Taravella M, Walker M. Corneal edema, postoperative. eMedicine Ophthalmology Topic 64. Omaha, NE: eMedicine.com; updated September 19, 2001.
  20. Brandt JD. Corneal thickness in glaucoma screening, diagnosis, and management. Curr Opin Ophthalmol. 2004;15(2):85-89.
  21. Rabinowitz YS, Rasheed K, Yang H, Elashoff J. Accuracy of ultrasonic pachymetry and videokeratography in detecting keratoconus. J Cataract Refract Surg. 1998;24(2):196-201.
  22. Weissman BA, Yeung KK. Keratoconus. eMedicine Ophthalmology Topic 104. Omaha, NE: eMedicine.com; updated January 29, 2005. 
  23. Sultan G, Baudouin C, Auzerie O, et al. Cornea in Marfan disease: Orbscan and in vivo confocal microscopy analysis. Invest Ophthalmol Vis Sci. 2002;43(6):1757-1764.
  24. Shih CY, Graff Zivin JS, Trokel SL, Tsai JC. Clinical significance of central corneal thickness in the management of glaucoma. Arch Ophthalmol. 2004;122:1270-1275.
  25. Li EY, Mohamed S, Leung CK, et al. Agreement among 3 methods to measure corneal thickness: Ultrasound pachymetry, Orbscan II, and Visante anterior segment optical coherence tomography. Ophthalmology. 2007;114(10):1842-1827.
  26. Ciolino JB, Khachikian SS, Belin MW. Comparison of corneal thickness measurements by ultrasound and scheimpflug photography in eyes that have undergone laser in situ keratomileusis. Am J Ophthalmol. 2008;145(1):75-80.
  27. Cheng AC, Rao SK, Lau S, et al. Central corneal thickness measurements by ultrasound, Orbscan II, and Visante OCT after LASIK for myopia. J Refract Surg. 2008;24(4):361-365.
  28. Schiano Lomoriello D, Lombardo M, et al. Repeatability of intra-ocular pressure and central corneal thickness measurements provided by a non-contact method of tonometry and pachymetry. Graefes Arch Clin Exp Ophthalmol. 2011;249(3):429-434.
  29. Modis L Jr, Szalai E, Nemeth G, Berta A. Reliability of the corneal thickness measurements with the Pentacam HR imaging system and ultrasound pachymetry. Cornea. 2011;30(5):561-566.
  30. Garcia-Medina JJ, Garcia-Medina M, Garcia-Maturana C, et al. Comparative study of central corneal thickness using Fourier-domain optical coherence tomography versus ultrasound pachymetry in primary open-angle glaucoma. Cornea. 2013;32(1):9-13.
  31. Wu W, Wang Y, Xu L. Meta-analysis of Pentacam vs. ultrasound pachymetry in central corneal thickness measurement in normal, post-LASIK or PRK, and keratoconic or keratoconus-suspect eyes. Graefes Arch Clin Exp Ophthalmol. 2014;252(1):91-99.
  32. Nassiri N, Sheibani K, Safi S, et al. Central corneal thickness in highly myopic eyes: Inter-device agreement of ultrasonic pachymetry, Pentacam and Orbscan II before and after photorefractive keratectomy. J Ophthalmic Vis Res. 2014;9(1):14-21.
  33. Bayhan HA, Aslan Bayhan S, Can I. Comparison of central corneal thickness measurements with three new optical devices and a standard ultrasonic pachymeter. Int J Ophthalmol. 2014;7(2):302-308.
  34. Khaja WA, Grover S, Kelmenson AT, et al. Comparison of central corneal thickness: Ultrasound pachymetry versus slit-lamp optical coherence tomography, specular microscopy, and Orbscan. Clin Ophthalmol. 2015;9:1065-1070.
  35. Sadoughi MM, Einollahi B, Einollahi N, et al. Measurement of central corneal thickness using ultrasound pachymetry and Orbscan II in normal eyes. J Ophthalmic Vis Res. 2015;10(1):4-9.
  36. Jacobs DS. Open-angle glaucoma: Epidemiology, clinical presentation, and diagnosis. UpToDate [online serial], Waltham, MA: UpToDate; reviewed May 2016.
  37. Shajari M, Jaffary I, Herrmann K, et al. Early tomographic changes in the eyes of patients with keratoconus. J Refract Surg. 2018;34(4):254-259.
  38. Bohm M, Shajari M, Remy M, Kohnen T. Corneal densitometry after accelerated corneal collagen cross-linking in progressive keratoconus. Int Ophthalmol. 2019;39(4):765-775.