Background

Optical Coherence Tomography

Optical coherence tomography (OCT) is a noninvasive, high-resolution imaging method that can be used to visualize ocular structures. OCT creates an image of light reflected from the ocular structures. In this technique, a reflected light beam interacts with a reference light beam. The coherent (positive) interference between the 2 beams (reflected and reference) is measured by an interferometer, allowing construction of an image of the ocular structures. This method allows cross-sectional imaging at a resolution of 6 to 25 μm.

The Stratus OCT, which uses a 0.8-μm wavelength light source, was designed to evaluate the optic nerve head, retinal nerve fiber layer, and retinal thickness in the posterior segment. The Zeiss Visante OCT and AC Cornea OCT use a 1.3-μm wavelength light source designed specifically for imaging the anterior eye segment. Light of this wavelength penetrates the sclera, permitting high-resolution cross-sectional imaging of the anterior chamber (AC) angle and ciliary body. The light is, however, typically blocked by pigment, preventing exploration behind the iris. Ultrahigh resolution OCT can achieve a spatial resolution of 1.3 μm, allowing imaging and measurement of corneal layers.

An early application of OCT technology was the evaluation of the cornea before and after refractive surgery. Because this noninvasive procedure can be conducted by a technician, it has been proposed that this device may provide a rapid diagnostic and screening tool for detecting angle-closure glaucoma.

Other Diagnostic Tools

OCT of the anterior eye segment is being evaluated as a noninvasive diagnostic and screening tool with a number of potential applications. One proposed use of anterior segment OCT is to determine whether there is a narrowing of the AC angle, which could lead to angle-closure glaucoma. Another general area of potential use is as a pre- and postsurgical evaluation tool for of AC procedures. This could include assessment of corneal thickness and opacity, calculation of intraocular lens power, guiding surgery, imaging intracorneal ring segments, and assessing complications following surgical procedures such as blockage of glaucoma tubes or detachment of Descemet membrane following endothelial keratoplasty (see 'Endothelial Keratoplasty' - Policy #103 in the Surgery Section). A third general category of use is to image pathologic processes such as dry eye syndrome, tumors, noninfectious uveitis, and infections. It is proposed that AS OCT provides better images than slit-lamp biomicroscopy/gonioscopy and ultrasound biomicroscopy due to higher resolution; in addition, AS OCT does not require probe placement under topical anesthesia.

Alternative methods of evaluating the AC are slit-lamp biomicroscopy or ultrasound biomicroscopy. Slit-lamp biomicroscopy is typically used to evaluate the AC; however, the chamber angle can only be examined with specialized lenses, the most common being the gonioscopic mirror. In this procedure, a gonio lens is applied to the surface of the cornea, which may result in distortion of the globe. Ultrasonography may also be used for imaging the anterior eye segment.^1, Ultrasonography uses high-frequency mechanical pulses (10-20 MHz) to build a picture of the front of the eye. An ultrasound scan along the optical axis assesses corneal thickness, AC depth, lens thickness, and axial length. Ultrasound scanning across the eye creates a 2-dimensional image of the ocular structures. It has a resolution of 100 μm but only moderately high intraobserver and low interobserver reproducibility. Ultrasound biomicroscopy (»50 MHz) has a resolution of 30 to 50 μm. As with slit-lamp biomicroscopy with a gonioscopic mirror, this technique requires placement of a probe under topical anesthesia.

Classification and Assessment of Glaucoma

Glaucoma is characterized by degeneration of the optic nerve.

The classification of glaucoma as open angle or angle closure relies on assessment of the AS anatomy, particularly that of the AC angle. Angle-closure glaucoma is characterized by obstruction of aqueous fluid drainage through the trabecular meshwork (the primary fluid egress site) from the eye’s AC. The width of the angle is a factor affecting the drainage of aqueous humor. A wide unobstructed iridocorneal angle permits sufficient drainage of aqueous humor, whereas a narrow angle may impede the drainage system and leave the patient susceptible to an increase in intraocular pressure and angle-closure glaucoma.

A comprehensive ophthalmologic examination for glaucoma includes assessment of the optic nerve and retinal nerve fiber layer (see 'Ophthalmologic Techniques that Evaluate the Posterior Segment for Glaucoma' - Policy 005 in the Medicine Section), 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 intraocular pressure, is sufficient for a definitive diagnosis of glaucoma.

Regulatory Status

Multiple OCT systems have been cleared for marketing by the U.S. Food and Drug Administration (FDA) through the 510(k) process. Examples of approved systems are the Visante™ OCT (Carl Zeiss Meditec); the RTVue® (Optovue) (FDA product code: HLI); and the Slit Lamp OCT (SL-OCT; Heidelberg Engineering) (FDA product code: MXK). The microscope-integrated OCT devices for intraoperative use include the ReScan 700 (Zeiss) and the iOCT® system (Haag-Streit). Portable devices for intraoperative use include the Bioptigen Envisu™ (Bioptigen) and the Optovue iVue® (Optovue). Ultrahigh resolution OCT devices include the SOCT Copernicus HR (Optopol Technologies).

Commercially available laser systems, such as the LenSx® (Alcon), Catalys® (OptiMedica), and VICTUS® (Technolas Perfect Vision), include OCT to provide image guidance for laser cataract surgery. FDA product code: OOE.

Custom-built devices, which do not require FDA approval, are also used.

The AC Cornea OCT (Ophthalmic Technologies) is not cleared for marketing in the United States.

Table 1. Ocular Imaging Devices Cleared by the US Food and Drug Administration

Device	Manufacturer	Date Cleared	510(k) No.	Indication
Avanti	Optovue Inc.	6/8/2018	K180660	Anterior segment optical coherence tomography
iVue	Optovue Inc.	6/9/2017	K163475	Anterior segment optical coherence tomography
VX130 Ophthalmic Diagnostic Device	LUNEAU SAS	4/24/2017	K162067	Anterior segment optical coherence tomography
LSFG-NAVI	Softcare Co. Ltd	5/12/2016	K153239	Anterior segment optical coherence tomography
RTVue XR OCT Avanti with AngioVue Software	OPTOVUE INC.	2/11/2016	K153080	Anterior segment optical coherence tomography
Pentacam AXL	OCULUS OPTIKGERATE GMBH	1/20/2016	K152311	Anterior segment optical coherence tomography
EnFocus 2300 EnFocus 4400	BIOPTIGEN INC.	12/2/2015	K150722	Anterior segment optical coherence tomography
ARGOS	SANTEC CORPORATION	10/2/2015	K150754	Anterior segment optical coherence tomography
OCT-Camera	OptoMedical Technologies GmbH	3/4/2015	K142953	Anterior segment optical coherence tomography
PROPPER INSIGHT BINOCULAR INDIRECT OPHTHALMOSOPE	PROPPER MANUFACTURING CO.INC.	9/17/2014	K141638	Anterior segment optical coherence tomography
CENTERVUE MACULAR INTEGRITY ASSESSMENT	CENTERVUE SPA	4/23/2014	K133758	Anterior segment optical coherence tomography
AMICO DH-W35 OPHTHALMOSCOPE SERIES	AMICO DIAGNOSTIC INCORPORATED	3/26/2014	K131939	Anterior segment optical coherence tomography
IVUE 500	OPTOVUE INC.	3/19/2014	K133892	Anterior segment optical coherence tomography

Related Policies

• Computerized Corneal Topography/Videokeratography (Policy #003 in the Medicine Section)
• Ophthalmologic Techniques that Evaluate the Posterior Segment for Glaucoma (Policy 005 in the Medicine Section)
• Aqueous Shunts and Stents for Glaucoma (Policy #060 in the Medicine Section)
• Endothelial Keratoplasty (Policy #103 in the Surgery Section)

For members enrolled in Medicaid and NJ FamilyCare plans, Horizon BCBSNJ applies the above medical policy.

FIDE SNP:

For members enrolled in a Fully Integrated Dual Eligible Special Needs Plan (FIDE-SNP): (1) to the extent the service is covered under the Medicare portion of the member’s benefit package, the above Medicare Coverage statement applies; and (2) to the extent the service is not covered under the Medicare portion of the member’s benefit package, the above Medicaid Coverage statement applies.

[RATIONALE: This policy was created in 2010 and has been updated regularly with searches of the MEDLINE database. The most recent literature update was performed through January 6, 2019.

Evidence reviews assess whether a medical test is clinically useful. A useful test provides information to make a clinical management decision that improves the net health outcome. That is, the balance of benefits and harms is better when the test is used to manage the condition than when another test or no test is used to manage the condition.

The first step in assessing a medical test is to formulate the clinical context and purpose of the test. The test must be technically reliable, clinically valid, and clinically useful for that purpose. Evidence reviews assess the evidence on whether a test is clinically valid and clinically useful. Technical reliability is outside the scope of these reviews, and credible information on technical reliability is available from other sources.

Angle-closure glaucoma

Clinical Context and Test Purpose

One potential use of anterior segment (AS) optical coherence tomography (OCT) is to determine whether there is a narrowing of the anterior chamber (AC) angle, which could lead to angle-closure glaucoma. There are 2 scenarios where this might occur: (1) for the diagnosis of angle-closure glaucoma and (2) as a screening method for future angle-closure glaucoma.

The question addressed in this policy is: Does AS OCT of the AC improve health outcomes compared with alternative methods in those with glaucoma?

The following PICOTS was used to select literature is relevant to the review.

Patients

The population of interest is individuals being evaluated for angle-closure glaucoma as part of a diagnostic or screening test.

Interventions

The test being considered is OCT of the anterior eye segment.

Comparators

Alternative tests are gonioscopy or ultrasound biomicroscopy (UBM), which are the commonly used. OCT is proposed to be an improvement over gonioscopy and UBM because OCT has higher resolution and does not require a probe placed under topical anesthesia.

Outcomes

The outcomes of interest are the diagnostic accuracy of AS OCT compared with other methods, and the effect of the test on health outcomes, including prediction of angle-closure glaucoma, change in glaucoma status, and prevention of glaucoma.

Timing

The appropriate duration of follow-up is the time interval needed to detect the development of an increase in intraocular pressure or angle-closure glaucoma. One longitudinal study (Baskaran et al, 2015) reported on 4-year follow-up after AS OCT.^2, In this study, 17% of participants developed gonioscopic angle closure by 4 years. Longer follow-up would be needed to evaluate the true-positive and false-positive rates.

Setting

This procedure is most likely to be administered in an outpatient facility by an ophthalmologist.

Simplifying Test Terms

There are 3 core characteristics for assessing a medical test. Whether imaging, laboratory, or other, all medical tests must be:

• Technically reliable
• Clinically valid
• Clinically useful.

Diagnostic tests detect presence or absence of a condition. Surveillance and treatment monitoring are essentially diagnostic tests over a time frame. Surveillance to see whether a condition develops or progresses is a type of detection. Treatment monitoring is also a type of detection because the purpose is to see if treatment is associated with the disappearance, regression, or progression of the condition.

Prognostic tests predict the risk of developing a condition in the future. Tests to predict response to therapy are also prognostic. Response to therapy is a type of condition and can be either a beneficial response or adverse response. The term predictive test is often used to refer to response to therapy. To simplify terms, we use prognostic to refer both to predicting a future condition or to predicting a response to therapy.

Technically Reliable

Assessment of technical reliability focuses on specific tests and operators and requires review of unpublished and often proprietary information. Review of specific tests, operators, and unpublished data are outside the scope of this policy and alternative sources exist. This policy focuses on the clinical validity and clinical utility.

Clinically Valid

A test must detect the presence or absence of a condition, the risk of developing a condition in the future, or treatment response (beneficial or adverse).

OCT vs Gonioscopy

A number of studies have compared OCT with gonioscopy for the detection of primary angle closure. For example, Nolan et al (2007) assessed the ability of a Visante OCT prototype to detect primary angle closure in 203 Asian patients.^3, The patients, recruited from glaucoma clinics, had been diagnosed with primary angle closure, primary open-angle glaucoma, ocular hypertension, and cataracts; some had previously been treated with iridotomy. Images were assessed by 2 glaucoma experts, and the results were compared with an independently obtained reference standard (gonioscopy). Data were reported from 342 eyes of 200 individuals. A closed angle was identified in 152 eyes with gonioscopy and in 228 eyes with OCT; agreement was obtained between the 2 methods in 143 eyes. Although these results suggested low specificity for OCT, gonioscopy is not considered a criterion standard. The authors suggested 3 possible reasons for the increase in identification of closed angles with OCT: lighting is known to affect angle closure, and the lighting conditions differed for the 2 methods (gonioscopy requires some light); placement of the gonioscopy lens on the globe may have caused distortion of the AS; and landmarks used differed between methods.

Narayanaswamy et al (2010) conducted a community-based cross-sectional study of glaucoma screening.^4, The study population consisted of individuals 50 years or older who underwent AS OCT by a single ophthalmologist and gonioscopy by an ophthalmologist masked to the OCT findings. Individuals were excluded if they had a disease or pathology that could influence the quality of angle imaging by OCT. The angle-opening distance (AOD) was calculated at 250, 500, and 750 μm from the scleral spur. Of 2047 individuals examined, 573 (28%) were excluded due to inability to locate the scleral spur, poor image quality, or software delineation errors. Of the remaining 1465 participants, only 315 (21.5%) had narrow angles on gonioscopy. A noted limitation of this quantitative technique for screening of angle-closure glaucoma was the inability to define the scleral spur in 25% of the study population.

A 2009 publication examined the sensitivity and specificity of the Visante OCT using different cutoff values for the AOD measured at 250, 500, and 750 μm from the scleral spur.^5, OCT and gonioscopy records were available for 303 eyes of 155 patients seen at a glaucoma clinic. Blinded analysis showed sensitivity and specificity between 70% and 80% (vs gonioscopy), depending on the AOD and the cutoff value. Correlation coefficients between the qualitative gonioscopy grade and quantitative OCT measurement ranged from 0.75 (AOD=250 μm) to 0.88 (AOD=750 μm). As noted by these investigators, “a truer measure of occludable angles is whether an eye develops angle-closure glaucoma in the future.”

Table 2. Summary of Key Nonrandomized Study Characteristics

Study	Study Type	Country	Dates	Participants	Treatment1	Treatment2	Follow Up
Nolan (2007)	Prospective, observational case series	Singapore	NR	Patients with suspected or confirmed primary angle closure (n=200 patient, 342 eyes)	AS-OCT	Gonioscopy	NR
Narayanaswamy (2010)	Cross-sectional	Singapore	NR	Patients age 50 years with phakic eyes (n=1465)	AS-OCT	Gonioscopy	NR

NR: not reported; AS-OCT: anterior segment optical coherence technology.

Table 3. Summary of Key Nonrandomized Study Results

Study	Detection of Angle Closure 1 Quadrants	Specificity with Gonioscopy as the Reference Standard.	AUC for AOD750 in the Nasal Quadrant	AUC for AOD750 in the Temporal Quadrant
Nolan (2007)
AS-OCT	142 (71%) patients	55.40%
	228 (66.7%) eyes
Gonioscopy	99 (49.5%) patients
	152 (44.4%) eyes
Narayanaswamy (2010)			0.9	0.91
95% CI			0.89-0.92	0.90-0.93

AUC: area under the receiver operating characteristic curve; AOD750: angle opening distance at 750 μm.

OCT vs UBM

Mansouri et al (2010) compared the measurement accuracy of the AC angle by AS OCT with UBM in patients with suspected primary angle-closure, primary angle-closure, or primary angle-closure glaucoma.^6, In this study, 55 eyes of 33 consecutive patients presenting with the 3 angle-closure conditions were examined with OCT and then UBM. The trabecular-iris angle was measured in all 4 quadrants. AOD was measured at 500 μm from the scleral spur. In this comparative study, OCT measurements correlated significantly with UBM measurements but showed poor agreement with each other. The authors concluded that AS OCT could replace UBM as a tool for assessing quantitatively the AC angle.

Clinically Useful

A test is clinically useful if the use of the results informs management decisions that improve the net health outcome of care. The net health outcome can be improved if patients receive correct therapy, or more effective therapy, or avoid unnecessary therapy, or avoid unnecessary testing.

Direct Evidence

Direct evidence of clinical utility is provided by studies that have compared health outcomes for patients managed with and without the test. Because these are intervention studies, the preferred evidence would be from randomized controlled trials.

The clinical utility of OCT is closely related to its ability to accurately diagnose or prevent angle-closure glaucoma, because treatment is generally initiated after confirmation of the diagnosis. Therefore, if OCT is more accurate in diagnosing clinically significant closed angles than alternatives, it can be considered to have clinical utility above that of the alternative tests.

A key question is whether the increase in cases of angle closure identified by AS OCT compared with the current standard of gonioscopy represents true cases of the disease. Baskaran et al (2015) reported on a comparative cohort study assessing the ability of OCT to predict incident gonioscopic angle closure.^2, A total of 2052 mostly Chinese participants attending a community health center underwent gonioscopy and AS OCT by examiners masked to the other test. Of the 342 participants evaluable for follow-up at 4 years, 65 had open angles on both tests at baseline (control group) and 277 had open angles on gonioscopy but closed angles determined by OCT at baseline (experimental group). At 4-year follow-up, 48 (17.3%) of the 277 patients in the experimental group had gonioscopic angle closure compared with none of the control group. The incidences of increased intraocular pressure and angle-closure glaucoma were not reported.

Chain of Evidence

Indirect evidence on clinical utility rests on clinical validity. If the evidence is insufficient to demonstrate test performance, no inferences can be made about clinical utility.

A chain of evidence cannot be constructed to link use of AS OCT of the AC to improved health outcomes compared with alternative methods in individuals with glaucoma.

Section Summary: Angle-Closure Glaucoma

A reproducibility study of angle metrics (ie, angle-opening, trabecular-iris space area, scleral spur angle) found high intraobserver reproducibility but modest interobserver reproducibility. In a comparative study, the primary landmark used to measure the AC angle (the scleral spur) could not be identified in a substantial number of eyes with AS OCT.

When compared with gonioscopy, AS OCT measurement of the AC angle detects more narrow angles than gonioscopy. It is not known whether these additional cases will lead to angle-closure glaucoma or if early detection will improve health outcomes

Results from a longitudinal study found that OCT detected more cases of mild angle closure than gonioscopy, and that some of these cases would develop angle closure as measured by gonioscopy. However, the study also indicated a potentially high number of false positives, and it is not known whether clinical outcomes would be improved with early monitoring based on AS OCT. Longitudinal studies are needed to determine whether eyes classified as closed by AS OCT, but not by gonioscopy, are at risk of developing primary angle-closure glaucoma.

Evaluation for Surgery or PostSurgical Complications

Clinical Context and Test Purpose

Another potential use of AS OCT is evaluation for AC surgical procedures. This could include a wide range of uses, such as the calculation of intraocular lens power, guiding surgery of the AS, imaging intracorneal ring segments, and assessing complications following surgical procedures such as blockage of glaucoma tubes or detachment of Descemet membrane after endothelial keratoplasty.

The question addressed in this policy is: Does AS OCT of the AC improve outcomes compared with alternative methods of assessing the AC for those who will or have had eye surgery?

The following PICOTS was used to select literature relevant to the review.

Patients

The population of interest is individuals who undergoing presurgical evaluation, surgical guidance, or postsurgical complications.

Interventions

The test being considered is OCT of the anterior eye segment.

Comparators

Alternative tests are clinical evaluation, slit-lamp biomicroscopy, or UBM.

Outcomes

The outcomes of interest are the diagnostic accuracy of OCT in visualizing the AS compared with alternative techniques, and the effect of the test on health outcomes, including successful outcomes for surgery and postsurgical monitoring.

Timing

The duration of follow-up for these studies is short-term efficacy of the surgical procedure or near postoperative evaluation for surgical complications.

Setting

The setting is a surgical suite or outpatient facility with an ophthalmologist.

Technically Reliable

Assessment of technical reliability focuses on specific tests and operators and requires review of unpublished and often proprietary information. Review of specific tests, operators, and unpublished data are outside the scope of this policy and alternative sources exist. This policy focuses on the clinical validity and clinical utility.

Clinically Valid

A test must detect the presence or absence of a condition, the risk of developing a condition in the future, or treatment response (beneficial or adverse).

Aqueous Tube Shunts

One potential application of OCT is visualization for surgical placement of aqueous tube shunts or stents. Jiang et al (2012) reported on a cross-sectional, observational study of the visualization of aqueous tube shunts by high-resolution OCT, slit-lamp biomicroscopy, and gonioscopy in 18 consecutive patients (23 eyes).^7, High-resolution OCT demonstrated shunt position and patency in all 23 eyes. Compared with slit-lamp, 4 eyes had new findings identified by OCT. For all 16 eyes in which tube entrance could be clearly visualized by OCT, growth of fibrous scar tissue could be seen between the tube and the corneal endothelium. This scar tissue was not identified (retrospectively analyzed) in the patient records of the slit-lamp examination.

Endothelial Keratoplasty

Use of OCT is being reported for intraoperative and postoperative evaluation of graft apposition and detachment in endothelial keratoplasty procedures. Moutsouris et al (2011) reported on a prospective comparison of AS OCT, Scheimpflug imaging, and slit-lamp biomicroscopy in 120 eyes of 110 patients after Descemet membrane endothelial keratoplasty.^8, All slit-lamp biomicroscopy and OCT examinations were performed by the same experienced technician, and all images were evaluated by 2 masked ophthalmologists. From a total of 120 Descemet membrane endothelial keratoplasty eyes, 78 showed normal corneal clearance by all 3 imaging techniques. The remaining 42 eyes showed persistent stromal edema within the first month, suggesting (partial) graft detachment. Biomicroscopy detected the presence or absence of a graft detachment in 35 eyes. Scheimpflug imaging did not provide additional information over biomicroscopy. In 15 eyes, only OCT discriminated between a “flat” graft detachment and delayed corneal clearance. Thus, of the 42 eyes, OCT provided added diagnostic value in 36% of cases. This led to further treatment in some of the additional cases. Specifically, a secondary Descemet stripping automated endothelial keratoplasty was performed for total graft detachment, while partial graft detachments were rebubbled or observed for corneal clearing. There were no false negatives (graft detachment unrecognized) or false positives (an attached graft recognized as a graft detachment).

Other Indications

Venincasa et al (2017) reported on combining grayscale and color images captured using AS OCT for of preparing for eye surgery.^9, Viewing an image in different colors provides different perspectives. The authors of this retrospective study determined that while grayscale is good for mapping extraocular muscle structures, the addition of color can improve the accuracy in finding the ideal point of insertion. Accuracy was measured as being within 1.00 mm of the intraoperative caliper measurement. One hundred thirty-nine AS OCT images were collected from 74 patients. When using grayscale and color imaging, AS OCT accuracy increased from 77% to 87%. Accuracy was lower (ie, falling outside the 1.00-mm range) when applying this practice to reoperations. The authors concluded that, especially for first time surgeries, use of combination imaging could be clinically useful.

Clinically Useful

A test is clinically useful if the use of the results informs management decisions that improve the net health outcome of care. The net health outcome can be improved if patients receive correct therapy, or more effective therapy, or avoid unnecessary therapy, or avoid unnecessary testing.

Direct Evidence

Direct evidence of clinical utility is provided by studies that have compared health outcomes for patients managed with and without the test. Because these are intervention studies, the preferred evidence would be from randomized controlled trials.

There is literature review on the risk-benefit of OCT laser-assisted cataract surgery vs traditional phacoemulsification.^10, OCT has found increasing roles in both preoperative surgical planning and postoperative evaluation and management for cataract surgery. However, additional studies are required to establish how OCT should be used to manage cataract surgery.

Chain of Evidence

Indirect evidence on clinical utility rests on clinical validity. If the evidence is insufficient to demonstrate test performance, no inferences can be made about clinical utility.

AS OCT is also being studied for preoperative evaluation of intraocular lens power as well as postoperative assessment of intraocular stability of phakic lens and optic changes related to intraocular lens or ocular media opacities. AS OCT is also being studied for imaging of intraocular stents and shunts and for imaging of graft detachment. However, it is unclear whether these imaging capabilities would improve health outcomes.

Section Summary: Evaluation for Surgery or Postsurgical Complications

The use of AS OCT has been reported for presurgical evaluation, surgical guidance, and monitoring for postsurgical complications. There is some evidence that the high-resolution images provided by AS OCT are superior to results from slit-lamp examination or gonioscopy for some indications. However, current literature is very limited and there is no clear link between AS OCT and improvements in health outcomes.

Anterior Segment Disease or Pathology

Clinical Context and Test Purpose

Anterior segment diseases represent a varied group of pathologies. AC OCT has been studied in the diagnosis of some of these.

The question addressed in this policy is: Does AS OCT of the AC improve outcomes compared with alternative methods of assessing anterior eye segment diseases or pathology?

The following PICOTS was used to select literature relevant to the review.

Patients

The population of interest is individuals being evaluated for AS disease or pathology.

Interventions

The test being considered is OCT of the anterior eye segment.

Comparators

Alternative tests are clinical evaluation, slit-lamp biomicroscopy, or UBM.

Outcomes

The outcomes of interests are diagnostic accuracy and the effect of the test on health outcomes, including symptoms and functional outcomes.

Timing

The duration of follow-up is short-term for diagnosis and treatment.

Setting

The setting is an outpatient facility with an ophthalmologist.

Technically Reliable

Assessment of technical reliability focuses on specific tests and operators and requires review of unpublished and often proprietary information. Review of specific tests, operators, and unpublished data are outside the scope of this policy and alternative sources exist. This policy focuses on the clinical validity and clinical utility.

Clinically Valid

A test must detect the presence or absence of a condition, the risk of developing a condition in the future, or treatment response (beneficial or adverse).

Neoplastic Disease

Several retrospective studies have compared OCT with UBM for assessing AS tumors. Bianciotto et al (2011) retrospectively analyzed 200 consecutive patients who underwent both AS OCT and UBM for AS tumors.^11, When comparing the image resolution of the 2 techniques, UBM had overall tumor visualization.

Uveitis of the AS

In a study from India, Agarwal et al (2009) evaluated the AC inflammatory reaction by high-speed AS OCT.^12, This prospective, nonrandomized, observational case series included 62 eyes of 45 patients. Of 62 eyes, grade 4 aqueous flare was detected by OCT imaging in 7 eyes and clinically in 5 eyes. The authors concluded that AS OCT can detect inflammatory reaction in uveitis and in eyes with decreased corneal clarity.

Other Indications

Garcia and Rosen (2008) evaluated the diagnostic performance of the AC Cornea OCT device by comparing image results with UBM in patients who had conditions of the AS.^13, Patients were recruited from various specialty clinics, and 80 eyes with pathologic conditions involving the anterior ocular segment were included. Comparison of OCT and UBM images showed that, while the AC Cornea OCT has high resolution for the cornea, conjunctiva, iris, and anterior angle, UBM images were also clear for these areas. In addition, UBM was found to be superior at detecting cataracts, anterior tumors, ciliary bodies, haptics, and posterior chamber intraocular lenses. OCT was found to be superior at detecting a glaucoma tube and a metallic foreign body in the cornea when imaging was performed in the coronal plane.

Clinically Useful

A test is clinically useful if the use of the results informs management decisions that improve the net health outcome of care. The net health outcome can be improved if patients receive correct therapy, or more effective therapy, or avoid unnecessary therapy, or avoid unnecessary testing.

Direct Evidence

Direct evidence of clinical utility is provided by studies that have compared health outcomes for patients managed with and without the test. Because these are intervention studies, the preferred evidence would be from randomized controlled trials.

The criterion standard for the diagnosis of ocular surface tumors such as ocular surface squamous neoplasia is histologic examination of tissue specimens from excisional biopsy.^14, In a review, Thomas et al (2014) noted that noninvasive methods of diagnosing ocular surface squamous neoplasia would be increasingly important as treatment moves toward medical therapy, although future studies would have to evaluate the diagnostic accuracy for this indication.^15, Additional studies are needed to further evaluate AS OCT for AS disease or pathology and to demonstrate the clinical utility of using OCT for these indications.

Chain of Evidence

Indirect evidence on clinical utility rests on clinical validity. If the evidence is insufficient to demonstrate test performance, no inferences can be made about clinical utility.

A chain of evidence cannot be constructed to link use of AS OCT of the AC to improved health outcomes compared with alternative methods in individuals with AS disease or pathology.

Section Summary: Anterior Segment Disease or Pathology

The evidence on use of AS OCT for AS disease or pathology, such as dry eye syndrome, tumors, uveitis, and infections, is limited. The evidence to date does not support an improvement using imaging compared with UBM.

Summary of Evidence

For individuals who are being evaluated for angle-closure glaucoma who receive AS OCT, the evidence includes case series and cohort studies. Relevant outcomes are test accuracy, symptoms, change in disease status, and morbid events. Current literature consists primarily of assessments of qualitative and quantitative imaging and detection capabilities. Ideally, a diagnostic test should be evaluated based on its diagnostic accuracy and clinical utility. Studies have shown that AS OCT detects more eyes with narrow or closed angles than gonioscopy, suggesting that the sensitivity of OCT is higher than that of gonioscopy. However, because of clinical follow-up and validation studies, it is not clear to what degree these additional cases are true positives or false positives and, therefore, the specificity and predictive values cannot be determined. The evaluation of diagnostic performance depends, therefore, on evidence that the additional eyes identified with narrow angle by AS OCT are at higher risk for primary angle-closure glaucoma. Results from a study with mid-term follow-up have shown that some patients identified with angle closure on AS OCT will develop angle closure on gonioscopy after several years, but that there may also be a large number of false-positive results. Longer term studies are needed to determine whether eyes classified as closed angle by AS OCT are at higher risk of developing primary angle-closure glaucoma. It is also not known whether early detection of angle closure will improve outcomes in individuals who do not have symptoms of angle closure. The evidence is insufficient to determine the effects of the technology on health outcomes.

For individuals who are being evaluated for anterior eye surgery or postsurgical complications who receive AS OCT, the evidence includes case series. Relevant outcomes are test accuracy, symptoms, change in disease status, and morbid events. Use of AS OCT has been reported for presurgical evaluation, surgical guidance, and monitoring for postsurgical complications. There is some evidence that the high-resolution images provided by AS OCT are superior to results from slit-lamp examination or gonioscopy for some indications. However, current literature is very limited. The evidence is insufficient to determine the effects of the technology on health outcomes.

For individuals who have anterior eye segment disease or pathology who receive AS OCT, the evidence includes case series. Relevant outcomes are test accuracy, symptoms, change in disease status, and morbid events. The evidence related to the use of AS OCT for AS disease or pathology (eg, dry eye syndrome, tumors, uveitis, infections) is limited, and does not support improvements in imaging compared with alternative diagnostic techniques. The evidence is insufficient to determine the effects of the technology on health outcomes.

SUPPLEMENTAL INFORMATION

Clinical Input From Physician Specialty Societies and Academic Medical Centers

While the various physician specialty societies and academic medical centers may collaborate with and make recommendations during this process, through the provision of appropriate reviewers, input received does not represent an endorsement or position statement by the physician specialty societies or academic medical centers, unless otherwise noted.

In response to requests, input was received from 1 physician specialty society and 3 academic medical centers while this policy was under review in 2011. There was general, but not unanimous, agreement that optical coherence tomography (OCT) is investigational. Some reviewers commented that OCT may have application in specific conditions such as globe perforation, anterior segment (AS; iris) tumors, and in the postoperative care of endothelial keratoplasty cases.

Practice Guidelines and Position Statements

In 2015, the American Academy of Ophthalmology published a preferred practice pattern on primary angle closure.^16, The Academy stated that gonioscopy of both eyes should be performed on all patients in whom angle closure is suspected and that AS imaging should be considered when angle anatomy is difficult to assess on gonioscopy. AS imaging methods discussed were ultrasound biomicroscopy, Scheimpflug imaging, and AS OCT. It was noted that AS OCT is limited to evaluating the iridocorneal angle.

U.S. Preventive Services Task Force Recommendations

Not applicable.

Ongoing and Unpublished Clinical Trials

Some currently unpublished trials that might influence this review are listed in Table 1.

Table 1. Summary of Key Trials

NCT No.	Trial Name	Planned Enrollment	Completion Date
Ongoing
NCT01746537	Automated Analysis of Anterior Chamber Imflammation by Optical Coherence Tomography	1500	Jun 2018 (ongoing)
NCT02542644	Assessment of Corneal Graft Attachment in Patients With Fuchs Endothelial Corneal Dystrophy Following Descemet's Membrane Endothelial Keratoplasty Using Ultra-high Resolution Optical Coherence Tomography	80	Dec 2020

NCT: national clinical trial.]
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Horizon BCBSNJ Medical Policy Development Process:

This Horizon BCBSNJ Medical Policy (the “Medical Policy”) has been developed by Horizon BCBSNJ’s Medical Policy Committee (the “Committee”) consistent with generally accepted standards of medical practice, and reflects Horizon BCBSNJ’s view of the subject health care services, supplies or procedures, and in what circumstances they are deemed to be medically necessary or experimental/ investigational in nature. This Medical Policy also considers whether and to what degree the subject health care services, supplies or procedures are clinically appropriate, in terms of type, frequency, extent, site and duration and if they are considered effective for the illnesses, injuries or diseases discussed. Where relevant, this Medical Policy considers whether the subject health care services, supplies or procedures are being requested primarily for the convenience of the covered person or the health care provider. It may also consider whether the services, supplies or procedures are more costly than an alternative service or sequence of services, supplies or procedures that are at least as likely to produce equivalent therapeutic or diagnostic results as to the diagnosis or treatment of the relevant illness, injury or disease. In reaching its conclusion regarding what it considers to be the generally accepted standards of medical practice, the Committee reviews and considers the following: all credible scientific evidence published in peer-reviewed medical literature generally recognized by the relevant medical community, physician and health care provider specialty society recommendations, the views of physicians and health care providers practicing in relevant clinical areas (including, but not limited to, the prevailing opinion within the appropriate specialty) and any other relevant factor as determined by applicable State and Federal laws and regulations.

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Index:
Optical Coherence Tomography (OCT) of the Anterior Eye Segment
Anterior Eye Segment Optical Imaging
OCT
Visante OCT
Slit-Lamp OCT
RTVue

References:
1. Wolffsohn JS, Peterson RC. Anterior ophthalmic imaging. Clin Exp Optom. Jul 2006;89(4):205-214. PMID 16776728

2. Baskaran M, Iyer JV, Narayanaswamy AK, et al. Anterior segment imaging predicts incident gonioscopic angle closure. Ophthalmology. Dec 2015;122(12):2380-2384. PMID 26359189

3. Nolan WP, See JL, Chew PT, et al. Detection of primary angle closure using anterior segment optical coherence tomography in Asian eyes. Ophthalmology. Jan 2007;114(1):33-39. PMID 17070597

4. Narayanaswamy A, Sakata LM, He MG, et al. Diagnostic performance of anterior chamber angle measurements for detecting eyes with narrow angles: an anterior segment OCT study. Arch Ophthalmol. Oct 2010;128(10):1321-1327. PMID 20938002

5. Pekmezci M, Porco TC, Lin SC. Anterior segment optical coherence tomography as a screening tool for the assessment of the anterior segment angle. Ophthalmic Surg Lasers Imaging. Jul-Aug 2009;40(4):389-398. PMID 19634744

6. Mansouri K, Sommerhalder J, Shaarawy T. Prospective comparison of ultrasound biomicroscopy and anterior segment optical coherence tomography for evaluation of anterior chamber dimensions in European eyes with primary angle closure. Eye (Lond). Feb 2010;24(2):233-239. PMID 19444291

7. Jiang C, Li Y, Huang D, et al. Study of anterior chamber aqueous tube shunt by fourier-domain optical coherence tomography. J Ophthalmol. Jul 2012;2012:189580. PMID 22778909

8. Moutsouris K, Dapena I, Ham L, et al. Optical coherence tomography, scheimpflug imaging, and slit-lamp biomicroscopy in the early detection of graft detachment after descemet membrane endothelial keratoplasty. Cornea. Dec 2011;30(12):1369-1375. PMID 21993458

9. Venincasa MJ, Osigian CJ, Cavuoto KM, et al. Combination of anterior segment optical coherence tomography modalities to improve accuracy of rectus muscle insertion location. J AAPOS. Jun 2017;21(3):243-246. PMID 28526283

10. Nguyen P, Chopra V. Applications of optical coherence tomography in cataract surgery. Curr Opin Ophthalmol. Jan 2013;24(1):47-52. PMID 23197267

11. Bianciotto C, Shields CL, Guzman JM, et al. Assessment of anterior segment tumors with ultrasound biomicroscopy versus anterior segment optical coherence tomography in 200 cases. Ophthalmology. Jul 2011;118(7):1297-1302. PMID 21377736

12. Agarwal A, Ashokkumar D, Jacob S, et al. High-speed optical coherence tomography for imaging anterior chamber inflammatory reaction in uveitis: clinical correlation and grading. Am J Ophthalmol. Mar 2009;147(3):413-416 e413. PMID 19054493

13. Garcia JP, Jr., Rosen RB. Anterior segment imaging: optical coherence tomography versus ultrasound biomicroscopy. Ophthalmic Surg Lasers Imaging. Nov-Dec 2008;39(6):476-484. PMID 19065978

14. Medina CA, Plesec T, Singh AD. Optical coherence tomography imaging of ocular and periocular tumours. Br J Ophthalmol. Jul 2014;98(Suppl 2):ii40-46. PMID 24599420

15. Thomas BJ, Galor A, Nanji AA, et al. Ultra high-resolution anterior segment optical coherence tomography in the diagnosis and management of ocular surface squamous neoplasia. Ocul Surf. Jan 2014;12(1):46-58. PMID 24439046

16. American Academy of Ophthalmology. Preferred Practice Pattern: Primary angle closure. 2015; http://www.aaojournal.org/article/S0161-6420(15)01271-3/pdf. Accessed February 26, 2018.

Codes:
(The list of codes is not intended to be all-inclusive and is included below for informational purposes only. Inclusion or exclusion of a procedure, diagnosis, drug or device code(s) does not constitute or imply authorization, certification, approval, offer of coverage or guarantee of payment.)

CPT*

92132