Glaucoma is characterized by degeneration of the optic nerve (optic disc). Elevated intraocular pressure (IOP) has long been thought to be the primary etiology, but the relation between IOP and optic nerve damage varies among individuals, suggesting a multifactorial origin. The association between glaucoma and other vascular disorders such as diabetes or hypertension suggests vascular factors may play a role in glaucoma.

A comprehensive ophthalmologic exam is required for the diagnosis of glaucoma, but no single test is adequate to establish diagnosis. 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.

Optic Nerve/Retinal Nerve Fiber Layer (RNFL) Evaluation Techniques:

Confocal Scanning Laser Ophthalmoscopy (CSLO) - A laser-based image acquisition which produces a high contrast reproducible image that is used to estimate the thickness of the RNFL.
Scanning Laser Polarimetry (SLP) - A polarized laser beam used to estimate the thickness of the RNFL by comparing the results to a normative database.
Optical Coherence Tomography (OCT) - non-contact technique that uses near-infrared light to provide automated, objective images of the retina, optic nerve head, and RNFL.

Techniques to measure ocular blood flow or ocular blood velocity have been proposed as evaluation tools for glaucoma; however, data for these techniques remain limited. Ocular blood flow and pulsatile ocular blood flow involve continuous monitoring of intraocular pressure that is converted into a volume measurement using the known relationship between ocular pressure and ocular volume.

POLICY

Analysis of the optic nerve (retinal nerve fiber layer) in the diagnosis and evaluation of individuals with glaucoma or glaucoma suspects using the following techniques is considered medically necessary:
- Confocal Scanning Laser Ophthalmoscopy (CSLO)
- Scanning Laser Polarimetry (SLP)
- Optical Coherence Tomography (OCT)
The measurement of ocular blood flow, pulsatile ocular blood flow or blood flow velocity in the diagnosis and evaluation of glaucoma is considered investigational.

IMPORTANT REMINDERS

Any specific products referenced in this policy are just examples and are intended for illustrative purposes only. It is not intended to be a recommendation of one product over another, and is not intended to represent a complete listing of all products available. These examples are contained in the parenthetical e.g. statement.
We develop Medical Policies to provide guidance to Members and Providers. This Medical Policy relates only to the services or supplies described in it. The existence of a Medical Policy is not an authorization, certification, explanation of benefits or a contract for the service (or supply) that is referenced in the Medical Policy. For a determination of the benefits that a Member is entitled to receive under his or her health plan, the Member's health plan must be reviewed. If there is a conflict between the Medical Policy and a health plan or government program (e.g., TennCare), the express terms of the health plan or government program will govern.

ADDITIONAL INFORMATION

Although associations between ocular blood flow parameters and glaucoma have been described, evidence remains insufficient to establish their clinical utility or to demonstrate an improvement in clinical outcomes.

SOURCES

American Academy of Ophthalmology. (2025). Preferred Practice Pattern. Primary open-angle glaucoma. Retrieved April 17, 2026 from http://aao.org.

American Academy of Ophthalmology. (2025). Preferred Practice Pattern. Summary benchmarks for preferred practice pattern guidelines. Retrieved April 17, 2026 from http://aao.org.

American Academy of Ophthalmology. (2025). Preferred Practice Pattern. Primary open-angle glaucoma suspect. Retrieved April 17, 2026 from http://www.aao.org.

BlueCross BlueShield Association. Evidence Positioning System. (4:2026). Ophthalmologic techniques that evaluate the posterior segment for glaucoma. (9.03.06). Retrieved April 17, 2026 from www.bcbsaoca.com/eps/. (34 articles and/or guidelines reviewed)

CMS.gov: Centers for Medicare & Medicaid Services. Palmetto GBA. (2021, August). Scanning computerized ophthalmic diagnostic imaging (SCODI) (LCD ID L34431). Retrieved September 13, 2021 from https://www.cms.gov.

Mohindroo, C, Ichhpujani, P., & Kumar, S. (2016). Current imaging modalities for assessing ocular blood flow in glaucoma. Journal of Current Glaucoma Practice, 10 (3), 104-112. (Level 4 evidence)

U.S. Food and Drug Administration. (2006, October). Center for Devices and Radiological Health. 510(k) Premarket Notification Database. K063191. Retrieved February 24, 2012 from http://www.accessdata.fda.gov.

U.S. Food and Drug Administration. (2009, August). Center for Devices and Radiological Health. 510(k) Premarket Notification Database. K082016. Retrieved February 24, 2012 from http://www.accessdata.fda.gov.

U.S. Food and Drug Administration. (2010, April). Center for Devices and Radiological Health. 510(k) Premarket Notification Database. K091404. Retrieved November 11, 2013 from http://www.accessdata.fda.gov.

WuDunn, D., Takusagawa, H. L., Sit, A. J., Rosdahl, J. A., Radhakrishnan, S., Hoguet, A., et al. (2021). OCT angiography for the diagnosis of glaucoma: A report by the American Academy of Ophthalmology. Ophthalmology, 128 (8), 1222-1235, doi: 10.1016/j.ophtha.2020.12.027. (Level 2 evidence)

ORIGINAL EFFECTIVE DATE: 7/14/2012

MOST RECENT REVIEW DATE: 5/14/2026

ID_BA

Policies included in the Medical Policy Manual are not intended to certify coverage availability. They are medical determinations about a particular technology, service, drug, etc. While a policy or technology may be medically necessary, it could be excluded in a member's benefit plan. Please check with the appropriate claims department to determine if the service in question is a covered service under a particular benefit plan. Use of the Medical Policy Manual is not intended to replace independent medical judgment for treatment of individuals. The content on this Web site is not intended to be a substitute for professional medical advice in any way. Always seek the advice of your physician or other qualified health care provider if you have questions regarding a medical condition or treatment.

This document has been classified as public information.