BlueCross and BlueShield of Montana Medical Policy/Codes
Ophthalmologic Techniques for Evaluating Glaucoma
Chapter: Vision
Current Effective Date: July 18, 2013
Original Effective Date: October 13, 2011
Publish Date: July 18, 2013
Revised Dates: March 22, 2012; April 10, 2013

Glaucoma is a disease characterized by degeneration of the optic disc.  Elevated intraocular pressure has long been thought to be the primary etiology, but the relationship between intraocular pressure and optic nerve damage varies among patients, suggesting a multifactorial origin.  For example, some patients with clearly elevated intraocular pressure will show no optic nerve damage, while other patients with marginal or no pressure elevation will, nonetheless, show optic nerve damage.  The association between glaucoma and other vascular disorders such as diabetes or hypertension suggests vascular factors may play a role in glaucoma.  Specifically, it has been hypothesized that reductions in blood flow to the optic nerve may contribute to the visual field defects associated with glaucoma.

Conventional management of the patient with glaucoma principally involves drug therapy to control elevated intraocular pressures and serial evaluation of the optic nerve.  Standard methods of evaluation include careful direct examination of the optic nerve using ophthalmoscopy or stereophotography, or evaluation of visual fields.  There has been interest in developing more objective, reproducible techniques both to document optic nerve damage and to detect early changes in the optic nerve and retinal nerve fiber layer (RNFL) before the development of permanent visual field deficits.  Specifically, evaluating changes in the thickness of the RNFL has been investigated as a technique to diagnose and monitor glaucoma.  In addition, there has been interest in measuring ocular blood flow as a diagnostic and management tool for glaucoma. Several new techniques have been developed, and are described below:

Techniques to Evaluate the Optic Nerve/Retinal Nerve Fiber Layer

  • Confocal Scanning Laser Ophthalmoscopy:  Confocal scanning laser ophthalmoscopy (CSLO) is a laser-based image acquisition technique, which is intended to improve the quality of the examination compared to standard ophthalmologic examination. A laser is scanned across the retina along with a detector system. Only a single spot on the retina is illuminated at any time, resulting in a high-contrast image of great reproducibility that can be used to estimate the thickness of the RNFL. In addition, this technique does not require maximal mydriasis, which may be a problem in patients with glaucoma. The Heidelberg Retinal Tomograph is probably the most common example of this technology.
  • Scanning Laser Polarimetry:  The RNFL is birefringent, causing a change in the state of polarization of a laser beam as it passes.  A 780-nm diode laser is used to illuminate the optic nerve.  The polarization state of the light emerging from the eye is then evaluated and correlated with RNFL thickness.  Unlike CSLO, scanning laser polarimetry (SLP) can directly measure the thickness of the RNFL.  GDx® is a common example of a scanning laser polarimeter.  GDx® contains a normative database and statistical software package to allow comparison to age-matched normal subjects of the same ethnic origin.  The advantages of this system are that images can be obtained without pupil dilation, and evaluation can be done in about 10 minutes.  Current instruments have added enhanced and variable corneal compensation technology to account for corneal polarization.
  • Optical coherence tomography (OCT) uses near-infrared light to provide direct cross-sectional measurement of the RNFL. The principles employed are similar to those used in B-mode ultrasound except light, not sound, is used to produce the 2-dimensional images. The light source can be directed into the eye through a conventional slit-lamp biomicroscope and focused onto the retina through a typical 78-diopter lens. This system requires dilation of the patient’s pupil. OCT® is an example of this technology.
  • Doppler Ultrasonography:  Color Doppler imaging has also been investigated as a technique to measure the blood velocity in the retinal and choroidal arteries.

(Note: This policy only addresses uses of these techniques related to glaucoma.


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 are any exclusions 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

BCBSMT may consider analysis of the optic nerve (retinal nerve fiber layer) in the diagnosis and evaluation of patients with known or suspected glaucoma medically necessary when using scanning laser ophthalmoscopy, scanning laser polarimetry, and optical coherence tomography.


BCBSMT considers the measurement of ocular blood flow, pulsatile ocular blood flow or blood flow velocity with Doppler ultrasonography  experimental, investigational and unproven in the diagnosis and follow-up of patients with glaucoma.


The use of various techniques of retinal nerve fiber layer (RNFL) analysis, (confocal scanning laser ophthalmoscopy [CSLO], scanning laser polarimetry [SLP], and optical coherence tomography [OCT]) for the diagnosis and management of glaucoma were addressed by Blue Cross Blue Shield Association (BCBSA) Technology Evaluation Center (TEC) in 2001 and again in 2003.  The 2003 BCBSA TEC Assessment offered the following observations:

  • A variety of techniques to evaluate the RNFL were considered, including CSLO, SLP, and OCT.  All three devices use different principles to directly evaluate the RNFL.  All three devices give multiple specific measurement of the RNFL that can be followed up over time to evaluate a rate of change in the RNFL.  In theory, they are highly sensitive and can detect subtle changes to the RNFL earlier than standard qualitative evaluations.  The major potential benefit of these technologies is that they can provide a quantitative objective evaluation in contrast with the subjective evaluation provided by other methods of diagnosing and monitoring primary open angle glaucoma (POAG).
  • The BCBSA TEC Assessment evaluated whether adding RNFL analysis to other tests improves health outcomes.  It is assumed that RNFL analysis would not influence decisions to begin treatment for suspected POAG when intraocular pressure is elevated or results of two of three conventional tests are positive.  Conventional tests include ophthalmoscopic detection of atrophy of the optic nerve, visual field defect on perimetric testing, and increased intraocular pressure on tonometry.  In patients without clear indications for topical medication, signs of optic nerve atrophy on RNFL analysis seen in advance of meeting other current diagnostic criteria for POAG may be used to begin early treatment.  Using RNFL analysis to initiate early topical medication requires knowing how well RNFL results predict the development of visual loss.  If the RNFL analysis is a poor predictor of future visual loss, its use could lead to errors in management, leading, for example, to over treatment.
  • RNFL analysis may also play a role in monitoring patients who have already begun treatment for POAG.  Patients showing a failed response to treatment on RNFL analysis may be referred to take a different class of topical medication or to undergo laser trabeculoplasty.
  • The best evidence would be direct evidence comparing outcomes of management guided by conventional tests with and without RNFL analysis.  As this evidence is not available, the BCBSA TEC Assessment sought indirect evidence regarding diagnostic performance and whether use of RNFL analysis could influence management decisions and outcomes.  At a minimum, the BCBSA TEC Assessment concluded that there must be strong evidence that RNFL analysis predicts the development of visual field defects.  Only longitudinal studies can assess the ability of RNFL analysis to predict the development of visual loss.  However, cross-sectional studies can be informative about the occurrence of false-negative results on RNFL analysis.

The 2003 BCBSA TEC Assessment provided the following conclusions:

  • No randomized trials compare the health outcomes of management guided by conventional tests alone to outcomes of management guided by conventional tests plus RNFL analysis in the detection or monitoring of POAG.
  • The best available evidence on using RNFL analysis to predict visual loss comes from a study of scanning laser ophthalmoscopy (i.e., Heidelberg retinal tomography, HRT), in which 21 patients progressed from ocular hypertension to glaucoma (converters) and 164 patients did not progress (nonconverters).  Of the 21 converters, 13 had abnormal HRT results and in 11 of these the tests were positive before development of visual field defects (average lead time was 5.4 months).  Of the 164 nonconverters, 47 had abnormal results.
  • The positive predictive value of HRT, given the available data, was 22%.  The frequency of true positives and false positives in the Kamal et al. study may depend on the duration of follow-up completed in this study, which was a mean of at least 33 months.  If the frequency of true and false positives stays the same with more adequate follow-up, the consequence would be over treatment in 78% of patients with a positive HRT finding.  Additional follow-up is needed to show whether some false positives are late converters who become true positives.
  • Cross-sectional studies do not inform the prediction of future visual loss.  These studies can reveal whether RNFL analysis can detect prevalent cases of glaucoma.  RNFL analysis does not detect all prevalent cases; it is falsely negative in 14%–36% of cases among recent cross-sectional studies using predetermined diagnostic criteria or blinded test interpretation.
  • The available evidence does not permit conclusions on whether RNFL analysis predicts visual loss or whether its use would improve health outcomes by preserving vision.

Regarding optic nerve head analyzers, pulsatile ocular blood flow, or blood flow velocity (techniques not addressed by the TEC Assessment), there are similar deficiencies reported in the published literature.  Specifically, no data from published clinical trials document how these devices should be incorporated into clinical practice and whether treatment decisions based on the use of these devices result in improved patient outcomes compared with the conventional methods of evaluation.  Additional information is also needed to; 1) document the association between blood flow and glaucoma; 2) determine the relevant vessels for study considering the complex blood supply to the optic nerve; and  3) establish the range of normal values, particularly in relation to other factors such as blood pressure, heart rate, and compliance of the blood vessels.

A literature search was performed to identify relevant evidence focusing on longitudinal results, as emphasized in the BCBSA TEC Assessment.  Results are summarized below.

The CSLO Ancillary Study, a subset of the Ocular Hypertension Treatment Study (OHTS), was designed to determine whether annual optic disc topographic measurements can accurately predict visual field loss.  The OHTS randomized patients with elevated intraocular pressure to either topical hypotensive medication or observation.  Baseline data reported from the CSLO Ancillary Study did not allow reaching conclusions about how well RNFL analysis measurements predict visual loss over time.

Follow-up of the CSLO Ancillary Study was reported in 2005.  Of 438 participants, 34% had abnormal CSLO values according to HRT criteria.  The average interval between CSLO exams to POAG was 48.4 months (SD 25.2).  Eyes not developing POAG were followed up a mean of 79.5 months (SD 20.8).  Sensitivity of CSLO for development of POAG using HRT criteria was 55.6% (95% CI: 39.6 to 70.5), specificity 68.2% (95% CI: 63.5 to 72.5), and positive predictive value 13.5% (95% CI: 8.9 to 20.0).  The investigators concluded that "the current analysis did not directly determine whether the prediction model that includes baseline CSLO measurements is improved over the OHTS prediction model that includes baseline stereophotographic cup-disc ratio measurements…. Longer follow-up is required to evaluate the true predictive accuracy of CSLO measures."

Longitudinal results have also been reported from the University of California, San Diego Diagnostic Innovations in Glaucoma Study (DIGS).  In the first publication, eyes from 160 glaucoma suspects evaluated with scanning laser polarimetry (SLP) were followed up for 1.7 to 4.1 years.  Visual field damage developed in 16 (10%) participants.  Only relative risks for visual field damage were reported as opposed to sensitivities, specificities, and predictive values.  From 12 SLP parameters and a 13th calculated from those parameters, three were significantly associated with the visual field outcome in multivariate analyses (models were incorrectly specified owing to the small number of outcomes).  In a subsequent report, 114 glaucoma suspects were examined with OCT (one eye per patient).  Over a 4.2-year average follow-up, 23 (20%) developed changes consistent with glaucoma.  While the relative risk of developing glaucomatous changes was increased with thinner RNFL results (1.5-fold per 10 micrometers), sensitivities and specificities were not reported demonstrating clinical utility.

At Manchester Royal Eye Hospital, United Kingdom (UK), HRT and GDx systems were evaluated in cross-sectional (98 normal controls and 152 patients with POAG) and longitudinal studies (240 at risk of developing glaucoma due to high intraocular pressure or fellow eye with POAG and 75 with POAG).  With specificity set at 95%, sensitivities of the HRT and GDx in detecting POAG were 59% and 45%, respectively, in the cross-sectional study.  In the longitudinal study, patients were evaluated biannually over an average 3.5 year follow-up.  Evidence of visual field defects developed in 72 of the at risk group. 

Poor agreement was found between the HRT and GDx for development of visual field abnormalities.  Although sensitivities might vary according to definitions for conversion to a visual field defect, among patients with baseline HRT and GDx abnormalities, sensitivities could be as low as 13% to 39%.  The authors concluded that “on account of the fact that the HRT and GDx fail to detect a significant number of cases of conversion, they cannot provide a replacement for visual field examination.”

Kalaboukhova et al. enrolled 55 patients with OHT and POAG (34 and 25, respectively) who followed a median of 47 months (range, 22–86 months).  HRT was performed at entry (1998–2002) and re-examined between 2001 and 2005.  Based on optic disc photographs, eyes were classified as progressive or stable—22 showed progression.  From 25 parameters evaluated, five were accompanied by statistically significant areas under the receiver operating characteristic (ROC) curve.  However, no adjustments were made for multiple comparisons; the sample was small and one of convenience.

Finally, the American Academy of Ophthalmology (AAO) POAG Suspect and POAG Preferred Practice Patterns recommend evaluating the optic nerve and retinal nerve fiber layer.  The documents also state that “the preferred technique for optic nerve head and retinal nerve fiber layer evaluation involves magnified stereoscopic visualization (as with the slit-lamp biomicroscope), preferably through a dilated pupil.”

A technology assessment issued by the AAO in 2007 reviewed 159 studies published between January 2003 and February 2006, evaluating optic nerve head and RNFL devices used to diagnose or detect glaucoma progression.  A three-level rating scale appraisal of “evidence level” (following) was applied to each study.

  • Level I—studies reporting independent and blinded comparison of a cohort of consecutive patients with and without glaucoma all receiving the diagnostic test and reference standard.
  • Level II—studies reporting either independent masked or objective comparison in a sample of either nonconsecutive patients or a narrow spectrum of patients undergoing the diagnostic test and reference standard, or an independent blinded comparison of an appropriate patient spectrum but the reference standard not applied to all patients.
  • Level III—studies where the reference standard was not objective, unblinded, or independent; positive and negative tests were verified using different reference standards; or the study enrolled an inappropriate spectrum of patients.

Medeiros and colleagues compared case-control (cross-sectional) to longitudinal results assessing diagnostic accuracy of CSLO.  They concluded that results from case-control studies “may not be applicable to the clinically relevant population.”  No relevant publications of longitudinal studies were identified.

Numerous articles continue to describe findings from patients with known and suspected glaucoma using scanning laser ophthalmoscopy, scanning laser polarimetry, and optical coherence tomography.  Studies note that abnormalities may be detected on these examinations before functional changes are noted.  These techniques have become incorporated into glaucoma care and are viewed as an additional piece of information that may be useful in the clinical management of these patients.

The data for use of ocular blood flow or blood flow velocity remain limited.  Some recent publications described their use in studies comparing medication regimens in glaucoma.  Others have suggested that these parameters may be helpful in understanding the variability in visual field changes in patients with glaucoma, i.e., this may help explain why patients with similar levels of intraocular pressure may develop markedly different visual impairments.

2011 Update

The policy was updated with a literature search using MEDLINE through November 2010.

Studies continue to report on use of diagnosis and management techniques in patients with known and suspected glaucoma.  In addition, studies report correlation of changes in retinal nerve fiber analysis and changes in visual fields.

The literature review did not identify studies that demonstrate the clinical utility for use of pulsatile ocular blood flow or blood flow velocity in patients with glaucoma.  These techniques are used in evaluating various glaucoma treatments.  A recent publication reported on color Doppler imaging (CDI) in normal and glaucomatous eyes.  Using data from reported studies, a weighted mean was derived for the peak systolic velocity, end diastolic velocity and Pourcelot's resistive index in the ophthalmic, central retinal and posterior ciliary arteries.  Data from 3061 glaucoma patients and 1072 controls were included.  The mean values for glaucomatous eyes were within one standard deviation of the values for controls for most CDI parameters. Methodological differences created inter-study variance in CDI values, complicating the construction of a normative database and limiting its utility.  The authors noted that because the mean values for glaucomatous and normal eyes have overlapping ranges, caution should be used when classifying glaucoma status based on a single CDI measurement.  These techniques remain investigational.

Finally, measurement of ocular blood flow has also been studied as a technique for evaluating patients with glaucoma.  While reports of use have been longstanding, the report by Bafa from 2001 is one example, the clinical impact of this technique is not known.  Reports have commented on the complexity of these parameters and have also noted that these technologies are not commonly used in clinical settings.  Thus, because the impact on health outcomes is not known, measurement of ocular blood flow is an investigational technique.


In summary, optic nerve analysis using SCLO, SLP, and OCT has become one additional test that may be used in the diagnosis and management of patients with glaucoma and those who are glaucoma suspects.  These results are often considered along with other findings to make diagnostic and therapeutic decisions about glaucoma care.  Thus, this testing may be considered medically necessary.

In contrast, data on use of ocular blood flow, pulsatile ocular blood flow, and/or blood flow velocity are currently lacking.  Their relationship to clinical outcomes is not known; their use remains 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. 

Rationale for Benefit Administration
ICD-9 Codes

16.21, 38.24, 38.25, 88.90, 365.0- 365.89

ICD-10 Codes

H40-H40.9, H42

Procedural Codes: 92120, 92133, 93875, 0198T
  1. Rankin, S.J., Walman, B.E., et al.  Color Doppler imaging and spectral analysis of the optic nerve vasculature in glaucoma.  American Journal of Ophthalmology (1995) 119(6):685-93.
  2. Kaiser, H.J., Schoetzau, A., et al.  Blood-flow velocities of the extraocular vessels in patients with high-tension and normal-tension primary open-angle glaucoma.  American Journal of Ophthalmology (1997) 123(3):320-7.
  3. Cioffi, G.A.  Three assumptions: ocular blood flow and glaucoma.  Journal of Glaucoma (1998) 7(5):299-300.
  4. Fontana, L., Poinoosawmy, D., et al.  Pulsatile ocular blood flow investigation in asymmetric normal tension glaucoma and normal subjects.  British Journal of Ophthalmology (1998) 82(7):731-6.
  5. James, C.B.  Pulsatile ocular blood flow.  British Journal Ophthalmology (1998) 82(7):720-1.
  6. Kamal, D.S., Garway-Heath, D.F., et al.  Use of sequential Heidelberg retina tomograph images to identify changes at the optic disc in ocular hypertensive patients at risk of developing glaucoma.  British Journal of Ophthalmology (2000) 84(9):993-8.
  7. Retinal nerve fiber analysis for the diagnosis and management of glaucoma. Blue Cross Blue Shield Association Technology Evaluation Center Assessment.  Chicago, Illinois:  (2001 November) Volume 16, Tab 13.
  8. Bafa, M., Lambrinakis, I., et al.  Clinical comparison of the measurement of the IOP with the ocular blood flow tonometer, the Tonopen XL and the Goldmann applanation tonometer.  Acta Ophthalmol Scand (2001) 79(1):15-8.
  9. Evidence Based Guideline for Ophthalmologic Techniques to Evaluate Glaucoma.  Blue Cross Blue Shield Association Technology Evaluation Center Assessment.  Chicago, Illinois.  (2003 August) Volume 18, Tab 7.
  10. Mohammadi, K., Bowd, C., et al.  Retinal nerve fiber layer thickness measurements with scanning laser polarimetry predict glaucomatous visual field loss.  American Journal of Ophthalmology (2004) 138(4):592-601.
  11. Zangwill, L.M., Weinreb, R.N., et al.  The confocal scanning laser ophthalmoscopy ancillary study to the ocular hypertension treatment study: study design and baseline factors.  American Journal of Ophthalmology (2004) 137(2):219-27.
  12. Zangwill, L.M., Weinreb, R.N., et al.  Baseline topographic optic disc measurements are associated with the development of primary open-angle glaucoma:  the Confocal Scanning Laser Ophthalmoscopy Ancillary Study to the Ocular Hypertension Treatment Study.  Archives of Ophthalmology (2005) 123(9):1188-97.
  13. American Academy of Ophthalmology.  Primary open-angle glaucoma suspect.  Preferred practice pattern.  San Francisco: American Academy of Ophthalmology; (2005). Available at: . (accessed 2007 December).
  14. Lalezary, M., Medeiros, F.A., et al.  Baseline optical coherence tomography predicts the development of glaucomatous change in glaucoma suspects.  American Journal of Ophthalmology (2006) 142(4):576-82.
  15. Kalaboukhova, L., Fridhammar, V., et al.  Glaucoma follow-up by the Heidelberg Retina Tomograph. Graefes Arch Clin Exp Ophthalmology (2006 June) 244(6):654-62.
  16. Medeiros, F.A., Ng, D., et al.  The effects of study design and spectrum bias on the evaluation of diagnostic accuracy of confocal scanning laser ophthalmoscopy in glaucoma.  Invest Ophthalmology Visual Science (2007) 48(1):214-22.
  17. Lin, S.C., Singh, K., et al.  Optic nerve head and retinal nerve fiber layer analysis: a report by the American Academy of Ophthalmology. Ophthalmology (2007) 114(10):1937-49.
  18. Harris, A., Kagermann, L., et al.  Measuring and interpreting ocular blood flow and metabolism in glaucoma. Can J Ophthalmol (2008) 43(3):328-36.
  19. Chauhan, B.C., Hicolela, M.T., et al.  Incidence and rates of visual field progression after longitudinally measured optic disc change in glaucoma.  Ophthalmology (2009) 116(11):2110-8.
  20. Ophthalmologic Techniques of Evaluating Glaucoma.  Chicago, Illinois:  Blue Cross Blue Shield Association Medical Policy Manual (2009 November) Vision 9.03.06.
  21. Grewal, D.S., Sehi, M., et al.  Comparing rates of retinal nerve fibre layer loss with GDxECC using different methods of visual-field progression. Br J Ophthalmol (2010 September 9) ((Epub ahead of print).
  22. Rusia, D., Harris, A., et al.  Feasibility of creating a normative database of colour Doppler imaging parameters in glaucomatous eyes and controls.  Br J Ophthalmol (2010 November 24) (Epub ahead of print).
  23. Ophthalmologic Techniques of Evaluating Glaucoma.  Chicago, Illinois:  Blue Cross Blue Shield Association Medical Policy Manual (2011 January) Vision 9.03.06.
October 2011 New Policy:
March 2012 Policy updated with literature review through November 2011, Rationale revised; references added and reordered; policy statements unchanged
April 2013 Policy formatting and language revised.  Policy statement unchanged.
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Ophthalmologic Techniques for Evaluating Glaucoma