Medical policy: Ophthalmologic Techniques That Evaluate the Posterior Eye Segment

Policy number: MP 2.056

Effective date: 2/1/2026

Policy

Analysis of the optic nerve (retinal nerve fiber layer) may be considered medically necessary when using scanning laser ophthalmoscopy, scanning laser polarimetry, and optical coherence tomography in the diagnosis and evaluation of patients with any of the following:

• Glaucoma or glaucoma suspects;
• Multiple sclerosis;
• Increased intracranial pressure;
• Optic neuritis or optic nerve disorders.

Analysis of the optic nerve (retinal nerve fiber layer) for all other indications is considered investigational. There is insufficient evidence to support a general conclusion concerning the health outcomes or benefits associated with this procedure.

The use of a patient-initiated home optical coherence tomography device is considered investigational for all indications. There is insufficient evidence to support a general conclusion concerning the health outcomes or benefits associated with this procedure.

The measurement of ocular blood flow, pulsatile ocular blood flow, or blood flow velocity is considered investigational for all indications. There is insufficient evidence to support a general conclusion concerning the health outcomes or benefits associated with this procedure.

Cross-references:

• MP 2.028 Eye Care
• MP 2.085 Optical Coherence Tomography (OCT) of the Anterior Eye Segment
• MP 2.086 Retinal Telescreening for Diabetic Retinopathy

Product variations

This policy is only applicable to certain programs and products administered by Capital Blue Cross and subject to benefit variations. Please see additional information below.

FEP PPO - Refer to FEP Medical Policy Manual.

Description/Background

Several techniques have been developed to measure the thickness of the optic nerve/retinal nerve fiber layer (RNFL) as a method to diagnose and monitor glaucoma and other retinal diseases. Measurement of ocular blood flow is also being evaluated as a diagnostic and management tool for glaucoma.

Glaucoma

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 patients, suggesting a multifactorial origin. Some patients with chronically elevated IOP will show no optic nerve damage, while others with marginal or no pressure elevation will show optic nerve damage. The association between glaucoma and other vascular disorders (e.g., diabetes, 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.

Diagnosis and management of glaucoma

A comprehensive ophthalmologic exam is required for the diagnosis of glaucoma, but no single test is adequate to establish diagnosis. A comprehensive ophthalmologic examination includes assessment of the optic nerve, evaluation of visual fields, and measurement of ocular pressure. The presence of characteristic changes in the optic nerve or abnormalities in visual field, together with increased IOP, is sufficient for a definitive diagnosis. However, some patients will show ophthalmologic evidence of glaucoma with normal IOP. These cases of normal tension glaucoma (NTG) are considered to be a type of primary open-angle glaucoma (POAG). Angle-closure glaucoma is another type of glaucoma associated with an increase in IOP. The increased IOP in angle-closure glaucoma arises from a reduction in aqueous outflow from the eye due to a closed angle in the anterior chamber. Diagnosis of angle-closure glaucoma is detailed in MP 2.085.

Conventional management of patients with glaucoma principally involves drug therapy to control elevated IOPs and serial evaluation of the optic nerve to follow disease progression. Standard methods of evaluation include careful direct examination of the optic nerve using ophthalmoscopy or stereophotography, or evaluation of visual fields. There is 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 development of permanent visual field defects.

Specifically, evaluating changes in RNFL thickness has been investigated as a technique to diagnose and monitor glaucoma. However, IOP reduction is not effective in decreasing disease progression in significant numbers of patients with NTG, and in patients with NTG, there is never an increase in IOP. It has been proposed that vascular dysregulation is a significant cause of damage to the RNFL, and there is interest in measuring ocular blood flow as both a diagnostic and a management tool for glaucoma. Changes in blood flow to the retina and choroid may be particularly relevant for diagnosis and treatment of NTG. A variety of techniques have been developed, as described below. (Note: This policy only addresses techniques related to the evaluation of the optic nerve, RNFL, or blood flow to the retina and choroid in patients with glaucoma.)

Multiple sclerosis

This central nervous system disease involves an immune-mediated process, which directs an abnormal response from the body’s immune system to the central nervous system (the brain, spinal cord, and optic nerves). In up to 20% of multiple sclerosis (MS) patients, optic neuropathy may be the first demyelinating event. The most common type of involvement of the visual pathways is optic neuritis, which can result in varying degrees of visual loss.

Optic neuritis

Inflammation of the optic nerve. Often associated with MS, this demyelinating and inflammatory condition occurs in 50% of MS patients and is the presenting feature in 15 to 20 percent of patients. Typically, painful, monocular vision loss evolves over hours to a few days. OCT can detect RNFL thinning in 85% of patients with this condition.

Papilledema

Papilledema is optic disc swelling due to raised intracranial pressure. It occurs when raised intracranial pressure is transmitted to the optic nerve sheath. Typically bilateral, it is often discovered when individuals are evaluated for other symptoms. Visual symptoms are common, although rarely the presenting symptom. Diagnostic testing may include optical coherence tomography to monitor swelling and to determine changes surrounding the retina. Left untreated vision loss can occur.

Techniques to evaluate the optic nerve and RNFL

Confocal scanning laser ophthalmoscopy

Confocal scanning laser ophthalmoscopy (CSLO) is an image acquisition technique intended to improve the quality of the eye examination compared with standard ophthalmoscopic 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 RNFL thickness. In addition, this technique does not require maximal mydriasis, which may be problematic in patients with glaucoma. The Heidelberg Retinal Tomograph is probably the most common example of this technology.

Scanning laser polarimetry

The RNFL is birefringent (or biorefractive), meaning that it causes 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 SLP device. GDx contains a normative database and statistical software package that compare scan results with age-matched normal subjects and present the information in an advantage class. SLP and OCT have been studied for glaucomatous optic nerve changes and have demonstrated that abnormalities may be detected on these examinations before functional changes are noted.

Optical coherence tomography

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 analysis software is being developed to include optic nerve head parameters with spectral domain OCT, analysis of macular parameters, and hemodynamic parameters with Doppler OCT and OCT angiography.

Pulsatile ocular blood flow

The pulsatile variation in ocular pressure results from the flow of blood into the eye during cardiac systole. Pulsatile ocular blood flow can thus be detected by the continuous monitoring of intraocular pressure. The detected pressure pulse can then be converted into a volumetric measurement using the known relationship between ocular pressure and ocular volume. Pulsatile blood flow is primarily determined by the choroidal vessels, particularly relevant to patients with glaucoma, because the optic nerve is supplied in large part by choroidal circulation.

Techniques to measure ocular blood flow

A number of techniques have been developed to assess ocular blood flow. They include laser speckle flowgraphy, color Doppler imaging, Doppler Fourier domain OCT, laser Doppler velocimetry, confocal scanning laser Doppler flowmetry, and retinal functional imaging.

Laser speckle flowgraphy

Laser speckle is detected when a coherent light source such as laser light is dispersed from a diffusing surface such as retinal and choroidal vessels and the circulation of the optic nerve head. The varying patterns of light can be used to determine red blood cell velocity and retinal blood flow. However, due to differences in the tissue structure in different eyes, flux values cannot be used for comparisons between eyes. This limitation may be overcome by subtracting background choroidal blood flow results from the overall blood flow results in the region of interest.

Color Doppler imaging

Color Doppler imaging has also been investigated as a technique to measure the blood flow velocity in the retinal and choroidal arteries. This technique delivers ultrasound in pulsed Doppler mode with a transducer set on closed eyelids. The examination takes 30 to 40 minutes and is most effective for the mean velocity of large ophthalmic vessels such as the ophthalmic artery, the central retinal artery, and the short posterior ciliary arteries. However, total blood flow cannot be determined with this technique, and imaging is highly dependent on probe placement.

Doppler Fourier domain OCT

Doppler Fourier domain OCT is a noncontact imaging technique that detects the intensity of the light scattered back from erythrocytes as they move in the vessels of the ocular tissue. This induces a frequency shift that represents the velocity of the blood in the ocular tissue.

Laser Doppler velocimetry

Laser Doppler velocimetry compares the frequency of reflected laser light from a moving particle to stationary tissue.

Confocal scanning laser Doppler flowmetry

Confocal scanning laser Doppler flowmetry combines laser Doppler flowmetry with confocal scanning laser tomography. Infrared laser light is used to scan the retina, and the frequency and amplitude of Doppler shifts are determined from the reflected light. Determinations of blood velocity and blood volume are used to compute the total blood flow and create a physical map of retinal flow values.

Regulatory status

A number of confocal scanning laser ophthalmoscopy, scanning laser polarimetry, and optical coherence tomography (OCT) devices have been cleared by the U.S. Food and Drug Administration (FDA) through the 510(k) process for imaging the posterior eye segment. For example, the RTVue XR OCT Avanti™ (Optovue) is an OCT system indicated for the in vivo imaging and measurement of the retina, retinal nerve fiber layer, and optic disc as a tool and aid in the clinical diagnosis and management of retinal diseases. The RTVue XR OCT Avanti™ with Normative Database is a quantitative tool for comparing retina, retinal nerve fiber layer, and optic disk measurements in the human eye to a database of known normal subjects. It is intended as a diagnostic device to aid in the detection and management of ocular diseases. In 2016, the RTVue XR OCT with Avanti™ with AngioVue™ Software was cleared by FDA through the 510(k) process (K153080) as an aid in the visualization of vascular structures of the retina and choroid. FDA product code: HLI, OBO.

In 2012, the iExaminer™ (Welch Allyn) was cleared for marketing by FDA through the 510(k) process. The iExaminer™ consists of a hardware adapter and associated software (iPhone® App) to capture, store, send, and retrieve images from the PanOptic™ Ophthalmoscope (Welch Allyn) using an iPhone®. FDA product code: HKI.

Rationale

Summary of evidence

For individuals who have glaucoma or suspected glaucoma who receive imaging of the optic nerve and retinal nerve fiber layer, the evidence includes studies on diagnostic accuracy. Relevant outcomes are test accuracy, symptoms, morbid events, functional outcomes, and medication use. Confocal scanning laser ophthalmoscopy (CSLO), scanning laser polarimetry (SLP), and OCT can be used to evaluate the optic nerve and retinal nerve fiber layer in patients with glaucoma and suspected glaucoma. Numerous studies have described findings from patients with known and suspected glaucoma using CSLO, SLP, and OCT. These studies have reported that abnormalities may be detected on these examinations before functional changes are noted. The literature and specialty society guidelines have indicated that optic nerve analysis using CSLO, SLP, and OCT are established add-on tests that may be used to diagnose and manage patients with glaucoma and suspected glaucoma. The evidence is sufficient to determine that the technology results in a meaningful improvement in the net health outcome.

For individuals who have glaucoma or suspected glaucoma who receive evaluation of ocular blood flow, the evidence includes association studies. Relevant outcomes are test accuracy, symptoms, morbid events, functional outcomes, and medication use. Techniques to measure ocular blood flow or ocular blood flow velocity are used to determine appropriate glaucoma treatment options. The data for these techniques remain limited. Literature reviews have not identified studies addressing whether these techniques improve diagnostic accuracy or whether they improve health outcomes in patients with glaucoma. Some have suggested that these parameters may inform understanding of the variability in visual field changes in patients with glaucoma; however, data on use of ocular blood flow, pulsatile ocular blood flow, and blood flow velocity are currently lacking. The evidence is insufficient to determine the effects of the technology on health outcomes.

Definitions

Cup/disc ratio in ophthalmology is the mathematical relationship between the horizontal or vertical diameter of the physiologic cup and the diameter of the optic disc.

Diabetic retinopathy is a disorder of retinal blood vessels characterized by capillary microaneurysms, hemorrhage, exudates, and the formation of new vessels and connective tissue.

Intraocular pressure refers to the internal pressure of the eye regulated by resistance to the flow of aqueous humor through the fine sieve of the trabecular meshwork.

Disclaimer

Capital Blue Cross’ medical policies are used to determine coverage for specific medical technologies, procedures, equipment, and services. These medical policies do not constitute medical advice and are subject to change as required by law or applicable clinical evidence from independent treatment guidelines. Treating providers are solely responsible for medical advice and treatment of members. These polices are not a guarantee of coverage or payment. Payment of claims is subject to a determination regarding the member’s benefit program and eligibility on the date of service, and a determination that the services are medically necessary and appropriate. Final processing of a claim is based upon the terms of contract that applies to the members’ benefit program, including benefit limitations and exclusions. If a provider or a member has a question concerning this medical policy, please contact Capital Blue Cross’ Provider Services or Member Services.

Coding information

Note: This list of codes may not be all-inclusive, and codes are subject to change at any time. The identification of a code in this section does not denote coverage as coverage is determined by the terms of member benefit information. In addition, not all covered services are eligible for separate reimbursement.

Investigational; therefore, not covered:

Covered when medically necessary:

References

1. Mohindroo C, Ichhpujani P, Kumar S. Current imaging modalities for assessing ocular blood flow in glaucoma. J Curr Glaucoma Pract. Sep-Dec 2016; 10(3):104-112. PMID 27857490
2. Ervin AM, Boland MV, Myrowitz EH, et al. Screening for Glaucoma: Comparative Effectiveness (Comparative Effectiveness Review No. 59). Rockville, MD: Agency for Healthcare Research and Quality; 2012.
3. Michelson G, Lucente-Forte E, Oddone F, et al. Optic nerve head and fibre layer imaging for diagnosing glaucoma. Cochrane Database Syst Rev. Nov 30 2015; (11):CD008803. PMID 26618332
4. Lin SC, Singh K, Jampel HD, et al. Optic nerve head and retinal nerve fiber layer analysis: a report by the American Academy of Ophthalmology. Ophthalmology. Oct 2007; 114(10):1937-1949. PMID 17908595
5. Shiga Y, Omodaka K, Kunikata H, et al. Waveform analysis of ocular blood flow and the early detection of normal tension glaucoma. Invest Ophthalmol Vis Sci. Nov 2013; 54(12):7699-7706. PMID 24130177
6. Bafa M, Lambrinakis I, Dayan M, 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. Feb 2001; 79(1):15-18. PMID 11167279
7. Schmidl D, Garhofer G, Schmetterer L. The complex interaction between ocular perfusion pressure and ocular blood flow – relevance for glaucoma. Exp Eye Res. Aug 2011; 93(2):141-155. PMID 20866866
8. Harris A, Kagemann L, Ehrlich R, et al. Measuring and interpreting ocular blood flow and metabolism in glaucoma. Can J Ophthalmol. Jun 2008; 43(3):328-336. PMID 18443609
9. Abegao Pinto L, Willekens K, Van Keer K, et al. Ocular blood flow in glaucoma – the Leuven Eye Study. Acta Ophthalmol. Sep 2016; 94(6):592-598. PMID 26895610
10. Kuryseva NI, Parshunina OA, Shatalova EO, et al. Value of structural and hemodynamic parameters for the early detection of primary open-angle glaucoma. Curr Eye Res. Mar 2017; 42(3):411-417. PMID 27341295
11. Witkowska KJ, Bata AM, Czalietz G, et al. Optic nerve head and retinal blood flow relationship during isometric exercise as assessed with laser speckle flowgraphy. PLoS One. Sep 12 2017; 12(9):e0184722. PMID 28898284
12. Russo D, Harris A, Perri A, et al. Feasibility of creating a normative database of colour Doppler imaging parameters in glaucomatous eyes and controls. Br J Ophthalmol. Sep 2011; 95(9):1193-1198. PMID 21106991
13. Calvo P, Ferreras A, Polo V, et al. Predictive value of retrobulbar blood flow velocities in glaucoma suspects. Invest Ophthalmol Vis Sci. Jun 2012; 53(7):3875-3884. PMID 22589447
14. American Academy of Ophthalmology. Preferred Practice Pattern: Primary Open-Angle Glaucoma Suspect. 2015. (www.aaojournal.org)
15. Iorga RE, Moraru A, Ozturk MR, Costin D. The role of Optical Coherence Tomography in optic neuropathies. Rom J Ophthalmol. 2018; 62(1):3-14.
16. Lamirel C, Newman NJ, Biousse V. Optical coherence tomography (OCT) in optic neuritis and multiple sclerosis. Rev Neurol (Paris). 2010; 166(12):978-986. doi:10.1016/j.neurol.2010.03.024
17. Mollan SP, Davies B, Silver NC, et al. Idiopathic intracranial hypertension: consensus guidelines on management. Journal of Neurology, Neurosurgery & Psychiatry. 2018; 89:1088-1110.
18. Albrecht P, Blasberg C, Ringelstein M, et al. Optical coherence tomography for the diagnosis and monitoring of idiopathic intracranial hypertension. J Neurol. 2017; 264(7):1370-1380. doi:10.1007/s00415-017-8532-x
19. Scott CJ, Kardon RH, Lee AG, et al. Diagnosis and grading of papilledema in patients with raised intracranial pressure using optical coherence tomography vs clinical expert assessment using a clinical staging scale. Arch Ophthalmol. 2010; 128(6):705-711. doi:10.1001/archophthalmol.2010.94
20. Malhotra K, Padungkiatsagul T, Moss HE. Optical coherence tomography use in idiopathic intracranial hypertension. Ann Eye Sci. 2020; 5:7. doi:10.21037/aes.2019.12.06
21. Bierfang D. Overview and differential diagnosis of papilledema. In: UpToDate. Brazis P (Ed). UpToDate. Waltham, MA. Accessed April 6, 2022.
22. Olek MJ, Narayan RN, Frohman EM, et al. Manifestations of Multiple Sclerosis in Adults. In: UpToDate. Gonzalez-Scarano F (Ed). UpToDate. Waltham, MA. Accessed April 6, 2022.
23. Osborne B, Balcer L. Optic Neuritis: Pathophysiology, clinical feature, and diagnosis. In: UpToDate. Gonzalez-Scarano F (Ed). UpToDate. Waltham, MA. Accessed April 6, 2022.
24. Keenan TD, Goldstein M, Goldenberg D, Zur D, Shulman S, Loewenstein A. Prospective longitudinal pilot study: daily self-imaging with patient-operated home OCT in neovascular age-related macular degeneration. Ophthalmology Science. 2021; 2(1):100034.
25. JuDunn D, Takusagawa HL, Sit AJ, et al. OCT Angiography for the Diagnosis of Glaucoma: A Report by the American Academy of Ophthalmology. Ophthalmology. Aug 2021; 128(8):1222-1235. PMID 33632585
26. Gu C, Li A, Yu L. Diagnostic performance of laser speckle flowgraphy in glaucoma: a systematic review and meta-analysis. Int Ophthalmol. Nov 2021; 41(11):3877-3888.
27. Aizawa N, Yokoyama Y, Chiba N, et al. Reproducibility of retinal circulation measurements obtained using laser speckle flowgraphy-NAVI in patients with glaucoma. Clin Ophthalmol. 2011; 5:1171-1176. PMID 21887100
28. Gardiner SK, Cull G, Fortune B, et al. Increased Optic Nerve Head Capillary Blood Flow in Early Primary Open-Angle Glaucoma. Invest Ophthalmol Vis Sci. Jul 2019; 60(8):3110-3118. PMID 31323681
29. Iida Y, Akagi T, Nakanishi H, et al. Retinal Blood Flow Velocity Change in Parafoveal Capillary after Topical Tafluprost Treatment in Eyes with Primary Open-Angle Glaucoma. Sci Rep. Jul 10 2017; 7(1):5019. PMID 28694501
30. Association between mitochondrial DNA damage and ocular blood flow in patients with glaucoma. Br J Ophthalmol. Aug 2019; 103(8):1060-1065. PMID 30190366
31. Kiyota N, Kunikata H, Shiga Y, et al. Relationship between laser speckle flowgraphy and optical coherence tomography angiography measures of ocular microcirculation. Graefes Arch Clin Exp Ophthalmol. Aug 2017; 255(8):1633-1642. PMID 28462456
32. Kiyota N, Shiga Y, Suzuki S, et al. The Effect of Systemic Hyperoxia on Optic Nerve Head Blood Flow in Primary Open-Angle Glaucoma Patients. Invest Ophthalmol Vis Sci. Jun 01 2017; 58(7):3181-3188. PMID 28654983
33. Kiyota N, Kunikata H, Shiga Y, et al. Ocular microcirculation measurement with laser speckle flowgraphy and optical coherence tomography angiography in glaucoma. Acta Ophthalmol. Jun 2018; 96(4):e485-e492. PMID 29575676
34. Kobayashi W, Kunikata H, Omotaka K, et al. Correlation of optic nerve microcirculation with papilledema under normal tension glaucoma. J Ophthalmol. 2014; 2014:468908. PMID 25574382
35. Kohmoto R, Sugiyama T, Ueki M, et al. Correlation between laser speckle flowgraphy and optical coherence tomography angiography measurements in normal and glaucoma eyes. Clin Ophthalmol. 2019; 13:1799-1805. PMID 31571818
36. Kuroda F, Iwase T, Yamamoto K, et al. Correlation between blood flow on optic nerve head structure and functional changes in eyes with glaucoma. Sci Rep. Jan 20 2020; 10(1):729. PMID 31959837
37. Mursch-Edlmayr AS, Luft N, Podkowinski D, et al. Laser speckle flowgraphy derived characteristics of optic nerve head perfusion in normal tension glaucoma and healthy individuals: A Pilot Study. Sci Rep. Mar 28 2018; 8(1):5343. PMID 29593269
38. Mursch-Edlmayr AS, Luft N, Podkowinski D, et al. Differences in Optic Nerve Head Blood Flow Regulation in Normal Tension Glaucoma Patients and Healthy Controls as Assessed With Laser Speckle Flowgraphy During the Water Drinking Test. J Glaucoma. Jul 2019; 28(7):649-654. PMID 30959064
39. Mursch-Edlmayr AS, Pickl L, Calzetti G, et al. Comparison of Neurovascular Coupling between Normal Tension Glaucoma Patients and Healthy Individuals with Laser Speckle Flowgraphy. Curr Eye Res. Nov 2020; 45(11):1438-1442. PMID 32255706
40. Shiga Y, Kunikata H, Aizawa N, et al. Optic Nerve Head Blood Flow, as Measured by Laser Speckle Flowgraphy, Is Significantly Reduced in Preperimetric Glaucoma. Curr Eye Res. Nov 2016; 41(11):1447-1453. PMID 27159148
41. Takeyama A, Ishida K, Anraku A, et al. Comparison of Optical Coherence Tomography Angiography and Laser Speckle Flowgraphy for the Diagnosis of Normal-Tension Glaucoma. J Ophthalmol. 2018; 2018:1751857. PMID 29651339
42. Abegao Pinto L, Willekens K, Van Keer K, et al. Ocular blood flow in glaucoma – the Leuven Eye Study. Acta Ophthalmol. Sep 2016; 94(6):592-598. PMID 26895610
43. Kuryseva NI, Parshunina OA, Shatalova EO, et al. Value of Structural and Hemodynamic Parameters for the Early Detection of Primary Open-Angle Glaucoma. Curr Eye Res. Mar 2017; 42(3):411-417. PMID 27341295
44. Russo D, Harris A, Perri A, et al. Feasibility of creating a normative database of colour Doppler imaging parameters in glaucoma eyes and controls. Br J Ophthalmol. Sep 2011; 95(9):1193-1198. PMID 21106991
45. Calvo P, Ferreras A, Polo V, et al. Predictive value of retrobulbar blood flow velocities in glaucoma suspects. Invest Ophthalmol Vis Sci. Jun 2012; 53(7):3875-3884. PMID 22589447
46. Monavarfeshani A, Yan W, Pappas C, et al. Transcriptomic analysis of the ocular posterior segment completes a cell atlas of the human eye. Proc Natl Acad Sci U S A. 2023; 120(34). doi:10.1073/pnas.2306513120
47. He G, Zhang X, Zhuang X, et al. A novel exploration of the choroidal vortex vein system: incidence and characteristics of posterior vortex veins in healthy eyes. Invest Ophthalmol Vis Sci. 2024; 65(2):21. doi:10.1167/iovs.65.2.21
48. Boruah DK, Vishwakarma D, Gogoi P, Lal NR, Deuri A. Utility of High-Resolution Ultrasonography in the Evaluation of Posterior Segment Ocular Lesions Using Sensitivity and Specificity. Acta Med Litu. 2023; 30(2):171-180. PMID 38516520
49. Bhaskaran A, Babu M, Sudhakar NA, Kudu KP, Shashidhara BC. Study of retinal nerve fiber layer thickness in diabetic patients using optical coherence tomography. Indian J Ophthalmol. 2023; 71(3):920-926. doi:10.4103/IJO.IJO_1918_22
50. Skau M, Yri H, Sander B, et al. Diagnostic value of optical coherence tomography for intracranial pressure in idiopathic intracranial hypertension. Graefes Arch Clin Exp Ophthalmol. 2013; 251(2):567-574. doi:10.1007/s00417-012-2039-z