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Optical Coherence Tomography of the Anterior Eye Segment

Policy Number: MP-311

 

Latest Review Date: March 2019

Category:  Vision                                                                  

Policy Grade:  C

Description of Procedure or Service:

Optical coherence tomography (OCT) is a noninvasive, high-resolution imaging method that can be used to visualize ocular structures. OCT of the anterior segment (AS) is being evaluated as a noninvasive diagnostic and screening tool for detecting angle-closure glaucoma, for presurgical evaluation, surgical guidance, and for assessing complications following surgical procedures. It is also being studied as a tool to evaluate the pathologic processes of dry eye syndrome, tumors, uveitis, and infections.

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 (AS) OCT is to determine whether there is a narrowing of the anterior chamber angle, which could lead to angle closure glaucoma. Another general area of potential use is for presurgical and post-surgical evaluation of anterior chamber 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 MP 382 Endothelial Keratlplasty). 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. 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 (approximately 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.

An early application of OCT technology was the evaluation of the cornea before and after refractive surgery.  Since this is a non-invasive procedure that can be conducted by a technician, it has been proposed that this device may provide a rapid diagnostic and screening tool for the detection of angle closure in glaucoma. Glaucoma is a disease characterized by degeneration of the optic nerve (optic disc). A comprehensive ophthalmologic examination for glaucoma includes assessment of the optic nerve and retinal nerve fiber layer, 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 (IOP), is sufficient for a definitive diagnosis of glaucoma.

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 MP 465 Ophthalmologic Techniques for Evaluating Glaucoma on imaging of the optic nerve with posterior segment OCT), 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.

Policy:

Scanning computerized ophthalmic (e.g., optical coherence tomography) imaging of the anterior eye segment, is considered not medically necessary and investigational.

Key Points:

The most recent literature review was updated 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 AS OCT is to determine whether there is a narrowing of the anterior chamber 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 evidence review is: Does OCT of the anterior chamber leads to an improvement in health outcomes compared to alternative methods?

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

Patients

The population of interest is individuals who are being evaluated for angle closure glaucoma for diagnosis or screening test.

Interventions

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

Comparators

Alternative tests are gonioscopy or ultrasound biomicroscopy (UBM). 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. 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 used in outpatient care 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.

Because different specialties may use different terms for the same concept, we are highlighting the core characteristics. The core characteristics also apply to different uses of tests, such as diagnosis, prognosis, and monitoring treatment.

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 and 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 evidence review and alternative sources exist. This evidence review 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).

Optical Coherence Tomography versus 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 prototype of the Visante OCT to detect primary angle closure in 203 Asian patients. 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 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 228 eyes with OCT; agreement was obtained between the 2 methods in 143 eyes. Although these results suggest low specificity for OCT, it is noted that gonioscopy is not considered to be a criterion standard. The authors suggest 3 possible reasons for the increase in identification of closed angles with OCT: lighting is known to affect angle closure, and the lighting conditions were different for the two methods (gonioscopy requires some light); placement of the gonioscopy lens on the globe may have caused distortion of the AS; and landmarks are not the same with the 2 methods.

Narayanaswamy et al (2010) conducted a community-based cross-sectional study of glaucoma screening. The study population consisted of individuals 50 years or older who underwent ASOCT by a single ophthalmologist and gonioscopy by an ophthalmologist who was masked to the OCT findings. Individuals were excluded if they had a disease or pathology which could influence the quality of angle imaging by OCT. The angle opening distance (AOD) was calculated at 250, 500, and 750 microns from the scleral spur. Of 2047 individuals examined, 28% were excluded due to inability to locate the scleral spur, poor image quality, or software delineation errors. Of the remaining 1465 participants, 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 also examined the sensitivity and specificity of the Visante OCT when using different cutoff values for the AOD measured at 250, 500, and 750 microns from the scleral spur. 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% (in comparison with 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) to 0.88 (AOD= 750). As noted by these investigators, “a truer measure of occludable angles is whether an eye develops angle-closure glaucoma in the future.”

Table 1. 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 2. Summary of Key Nonrandomized Study Results

Study

Detection of

Angle Closure 1

Quad rants

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 versus Ultrasound Biomicroscopy

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 angleclosure glaucoma. 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 on 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 to the current standard of gonioscopy represents true cases of the disease. In 2015, Baskaran et al reported a comparative cohort study assessing the ability of OCT to predict incident gonioscopic angle closure. 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 to none of the control group. The incidence of increased IOP 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 study of reproducibility of angle metrics (i.e., 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 if 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 detects more cases of mild angle closure than gonioscopy, and that some of these cases will develop angle closure as measured by gonioscopy. However, the study also indicates a potentially high number of false positives, and it is not known whether clinical outcomes are 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 for evaluation for anterior chamber surgical procedures. This could include a wide range of uses, such as the calculation of intraocular lens power, guiding surgery of the AS, to image intracorneal ring segments, and to assess complications following surgical procedures such as blockage of glaucoma tubes or detachment of Descemet membrane after endothelial keratoplasty.

The question addressed in this evidence review 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 complications of surgery.

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 evidence review and alternative sources exist. This evidence review 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). 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. In 2011, Moutsouris et al reported a prospective comparison of AS OCT, Scheimpflug imaging, and slit-lamp biomicroscopy in 120 eyes of 110 patients after Descemet membrane endothelial keratoplasty (DMEK). 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 DMEK eyes, 78 showed a 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 give additional information over biomicroscopy. In 15 eyes, only OCT was able to discriminate between a “flat” graft detachment and delayed corneal clearance. Thus, out of the 42 eyes, OCT had an 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 (DSAEK) 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 via AS OCT for the purpose of preparing for eye surgery. 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 lowered (i.e., falling outside the 1.00-mm range) when applying this practice to reoperations. However, the authors concluded, 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. 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

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, the literature at this time is very limited and there is no clear link to improvements in health outcomes.

Anterior Eye 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 evidence review 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 who are being evaluated for anterior segment 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 technical performance and 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 a 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 evidence review and alternative sources exist. This evidence review 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 AS tumors. Bianciotto et al (2011) retrospectively analyzed 200 consecutive patients who underwent both AS OCT and UBM for AS tumors. When comparing image resolution for the 2 techniques, UBM was found to have better overall tumor visualization.

Uveitis of the AS

In a study from India, Agarwal et al (2009) evaluated the AC inflammatory reaction by highspeed AS OCT. 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 AC Cornea OCT device by comparing image results with UBM in patients with conditions of the AS.  Patients were recruited from various specialty clinics, and 80 eyes with pathologic conditions involving the anterior ocular segment were included in the study.  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 are 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 (OSSN) is histologic examination of tissue specimens from excisional biopsy. In a 2014 review, Thomas et al noted that noninvasive methods of diagnosing OSSN will be increasingly important as treatment moves toward medical therapy, although future studies would have to evaluate the diagnostic accuracy for this indication. 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 anterior segment disease or pathology, such as dry eye syndrome, tumors, uveitis, and infections is limited. However, the evidence to date does not support an improvement in imaging compared to 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 angleclosure 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 post-surgical complications who receive AS OCT, the evidence includes case series. Relevant outcomes include test accuracy, symptoms, change in disease status, and morbid events. Use of AS OCT has been reported for pre-surgical evaluation, surgical guidance, and monitoring for post-surgical 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, the literature at this time 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 include test accuracy, symptoms, change in disease status, and morbid events. The evidence on use of AS OCT for anterior segment disease or pathology, such as dry eye syndrome, tumors, uveitis, and 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.

Practice Guidelines and Position Statements

In 2015, the American Academy of Ophthalmology (AAO) published preferred practice patterns (PPP) on primary angle closure. AAO states 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, although it was noted that AS OCT is limited to evaluating the iridocorneal angle.

U.S. Preventive Services Task Force Recommendations

Not applicable.

Key Words:

Scanning computerized ophthalmic, optical coherence tomography, OCT, Stratus OCT™, Zeiss OCT™, Visante OCT non-contact, high resolution tomographic and biomicroscopic device, anterior imaging techniques, AC Cornea OCT, Bioptigen Envisu™, SOCT Copernicus HR, RTVue® (Optovue), Slit-Lamp OCT (SL-OCT, Heidelberg Engineering), ReScan 700 (Zeiss), Haag-Streit iOCT®,

Approved by Governing Bodies:

Multiple optical coherence tomography (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); and the Slit Lamp OCT (SL-OCT; Heidelberg Engineering). 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. 

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

Device

Manufacturer

Date Cleared

X510 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

K162037

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

 

Benefit Application:

Coverage is subject to member’s specific benefits.  Group specific policy will supersede this policy when applicable.

ITS: Home Policy provisions apply

FEP contracts: FEP does not consider investigational if FDA approved and will be reviewed for medical necessity.

Current Coding: 

CPT Codes:

92132

Scanning computerized ophthalmic diagnostic imaging, anterior segment, with interpretation and report, unilateral or bilateral.

References:

  1. Agarwal A, Ashokkumar D, Jaco S et al. High speed optical coherence tomography for imaging anterior chamber inflammatory reaction in uveitis: clinical correlation and grading. Am J Ophthalmol 2009; 147(3):413-6.

  2. American Academy of Ophthalmology. Preferred Practice Pattern: Primary angle closure. 2015; //www.aaojournal.org/article/S0161-6420 (15) 01271-3/pdf. Accessed July 28, 2016.

  3. Baskaran M, Iyer JV, Narayanaswamy AK, et al. Anterior Segment Imaging Predicts Incident Gonioscopic Angle Closure. Ophthalmology. Dec 2015; 122(12):2380-2384.

  4. 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 2011; 118(7):1297-302.

  5. Cauduro RS, Ferraz Cdo A, Morales MS et al. Application of anterior segment optical coherence tomography in pediatric ophthalmology. J Ophthalmol 2012; 2012:313120.

  6. Ehlers JP, Dupps WJ, Kaiser PK, et al. The Prospective Intraoperative and Perioperative Ophthalmic Imaging with Optical Coherence Tomography (PIONEER) Study: 2-Year Results. Am J Ophthalmol. Nov 2014; 158(5):999-1007 e1001.

  7. Ehlers JP, Kaiser PK, Srivastava SK. Intraoperative optical coherence tomography using the RESCAN 700: preliminary results from the DISCOVER study. Br J Ophthalmol. Oct 2014; 98(10):1329-1332.

  8. Garcia JP Jr, Rosen RB.  Anterior segment imaging: optical coherence tomography versus ultrasound biomicroscopy.  Ophthalmic Surg Lasers Imaging.  2008 Nov-Dec; 39(6):476-84.

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

  10. Kalev-Landoy M, Day AC, Cordeiro MF et al.  Optical coherence tomography in anterior segment imaging.  Acta Ophthalmol Scand 2007; 85(4):427-30.

  11. Leung CK, Li H, Weinreb RN, et al.  Anterior chamber angle measurement with anterior segment optical coherence tomography:  A comparison between slit lamp OCT and visante OCT.  Invest Ophthalmol Vis Sci 2008; 49: 3469-3474.

  12. 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) 2010; 24(2):233-9.

  13. Maram J, Pan X, Sadda S, et al. Reproducibility of Angle Metrics Using the Time-Domain Anterior Segment Optical Coherence Tomography: Intra-Observer and Inter-Observer Variability. Curr Eye Res. Jun 23 2014:1-5.

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

  15. 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 2011; 30(12):1369-75.

  16. 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 2010; 128(10):1321-7.

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

  18. Nolan W.  Anterior segment imaging:  Ultrasound biomicroscopy and anterior segment optical coherence tomography.  Curr Opin Ophthalmology, March 2008; 19(2): 115-121.

  19. Nolan WP, See JL, Chew PT et al.  Detection of primary angle closure using anterior segment optical coherence tomography in Asian eyes.  Ophthalmology 2007; 114(1):33-9.

  20. 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.  2009 Jul-Aug; 40(4):389-98.

  21. Shih CY, Ritterband DC, Palmiero PM et al. The use of postoperative slit-lamp optical coherence tomography to predict primary failure in Descemet stripping automated endothelial keratoplasty. Am J Ophthalmol 2009; 147(5):796-800.

  22. Steven P, Le Blanc C, Velten K et al. Optimizing descemet membrane endothelial keratoplasty using intraoperative optical coherence tomography. JAMA Ophthalmol 2013; 131(9):1135-42.

  23. Takezawa Y, Suzuki T, Shiraishi A. Observation of retrocorneal plaques in patients with infectious keratitis using anterior segment optical coherence tomography. Cornea. Oct 2017;36(10):1237-1242.

  24. 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.

  25. 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.

  26. Wang D, Pekmezci M, Basham RP, et al. Comparison of different modes in optical coherence tomography and ultrasound biomicroscopy in anterior chamber angle assessment. J Glaucoma, Aug 2009; 18(6): 472-478.

  27. Wolffsohn JS, Peterson RC. Anterior ophthalmic imaging.  Clin Exp Optom 2006; 89(4):205-14.

Policy History:

Medical Policy Group, December 2007 (2)

Medical Policy Administration Committee, January 2008

Available for comment January 5-February 20, 2008

Medical Policy Group, December 2008 (1)

Medical Policy Group, December 2009 (1)

Medical Policy Group, December 2010 (1): Description, Key Points updated, Key word added and info to Approved by Governing Body added, no policy change

Medical Policy Group, December 2010; 2011 coding update

Medical Policy Group, January 2011: Key Points, References

Medical Policy Panel February 2011

Medical Policy Panel, July 2011 (2): Key Points updated

Medical Policy Group, September 2012 (1): Update to Description, Key Points and References related to MPP update; no change to policy statement

Medical Policy Panel, February 2013

Medical Policy Group, February 2013 (2): Update to Description, Key Points, Governing bodies and References related to MPP update; no change to policy statement

Medical Policy Panel, February 2014

Medical Policy Group, February 2014 (1) Update to Key Points and References; no change to policy statement

Medical Policy Panel, February 2015

Medical Policy Group, February 2015 (6):  2015 Updates to Key Points, Key Words, Approved by Governing Bodies and References; no change in policy statement.

Medical Policy Panel, August 2016

Medical Policy Group, August 2016 (6): Updates to Key Points, Key Words, Summary, Approved by Governing Bodies and References. Clarified policy statement to include “of the anterior eye segment”

Medical Policy Panel, March 2017

Medical Policy Group, March 2017 (6): Updates to Description, Key Points, Summary, Approved by Governing Bodies; no change in policy statement.

Medical Policy Panel, April 2018

Medical Policy Group, April 2018 (6): Updates to Key Points and References; no change in policy statement.

Medical Policy Panel, March 2019

Medical Policy Group, March 2019 (6): Updates to Description, Key Points and Approved by Governing Bodies. Policy Title changed to “Optical Coherence Tomography of the Anterior Eye Segment”.  No change to policy statement.

This medical policy is not an authorization, certification, explanation of benefits, or a contract. Eligibility and benefits are determined on a case-by-case basis according to the terms of the member’s plan in effect as of the date services are rendered. All medical policies are based on (i) research of current medical literature and (ii) review of common medical practices in the treatment and diagnosis of disease as of the date hereof. Physicians and other providers are solely responsible for all aspects of medical care and treatment, including the type, quality, and levels of care and treatment.

This policy is intended to be used for adjudication of claims (including pre-admission certification, pre-determinations, and pre-procedure review) in Blue Cross and Blue Shield’s administration of plan contracts.

The plan does not approve or deny procedures, services, testing, or equipment for our members. Our decisions concern coverage only. The decision of whether or not to have a certain test, treatment or procedure is one made between the physician and his/her patient. The plan administers benefits based on the member’s contract and corporate medical policies. Physicians should always exercise their best medical judgment in providing the care they feel is most appropriate for their patients. Needed care should not be delayed or refused because of a coverage determination.

As a general rule, benefits are payable under health plans only in cases of medical necessity and only if services or supplies are not investigational, provided the customer group contracts have such coverage.

The following Association Technology Evaluation Criteria must be met for a service/supply to be considered for coverage:

1. The technology must have final approval from the appropriate government regulatory bodies;

2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes;

3. The technology must improve the net health outcome;

4. The technology must be as beneficial as any established alternatives;

5. The improvement must be attainable outside the investigational setting.

Medical Necessity means that health care services (e.g., procedures, treatments, supplies, devices, equipment, facilities or drugs) that a physician, exercising prudent clinical judgment, would provide to a patient for the purpose of preventing, evaluating, diagnosing or treating an illness, injury or disease or its symptoms, and that are:

1. In accordance with generally accepted standards of medical practice; and

2. Clinically appropriate in terms of type, frequency, extent, site and duration and considered effective for the patient’s illness, injury or disease; and

3. Not primarily for the convenience of the patient, physician or other health care provider; and

4. Not more costly than an alternative service or sequence of services at least as likely to produce equivalent therapeutic or diagnostic results as to the diagnosis or treatment of that patient’s illness, injury or disease.