Summary Of Evidence

Scanning computerized ophthalmic diagnostic imaging (SCODI) allows for the early detection of glaucomatous damage to the nerve fiber layer or optic nerve and has demonstrated clinical utility in facilitating earlier diagnosis and treatment as well as monitoring for progression and response to treatment. Evidence-based guidelines (2015 Academy of Ophthalmology [AAO] Preferred Practice Pattern [PPP] on Primary Open-Angle Glaucoma and 2010 American Optometric Association [AOA] Optometric Clinical Practice Guideline on Care of the Patient with Open Angle Glaucoma) identify SCODI as one technique that may be used to examine the optic nerve head (ONH) and/or retinal nerve fiber layer (RNFL). SCODI is often used to provide quantitative information to supplement the clinical exam of the optic nerve. SCODI is widely used in the posterior segment, whereas in the anterior segment, the use is still limited.

The evidence-based guideline from the AAO (2015 AAO PPP on Primary Angle Closure) indicates that anterior segment imaging should be considered when angle anatomy is difficult to assess on gonioscopy. There is good evidence demonstrating general agreement between findings on gonioscopy and anterior segment imaging, including ultrasound biomicroscopy and anterior segment optical coherence tomography (AS-OCT). However, AS-OCT is limited to evaluating the iridocorneal angle. AS-OCT is one technology that may prove useful in evaluating secondary causes of angle closure and elucidating plateau iris.

SCODI is also a valuable tool for the evaluation of patients with retinal disease, especially those with macular abnormalities. SCODI is often used in conjunction with clinical examination of the eye. It is at times used as a baseline and also used in monitoring for progression or response to treatment. The clinical utility of OCT imaging in retinal conditions has been demonstrated as providing an objective, accurate assessment of the amount and location of retinal thickening. Evidence-based guidelines from the AAO (PPP Diabetic Retinopathy [2016] and the PPP Idiopathic Macular Hole [2014, updated 2017]) support that in clinical practice, decisions are often based on OCT findings.

Finally, Marmor et al (AAO Statement 2016) published recommendations on screening patients who are being treated with Chloroquine and Hydroxychloroquine.  A baseline test is performed and then ongoing monitoring at regular intervals is recommended.  Marmor et al recommends beginning annual screening after 5 years for patients on acceptable doses of chloroquine or hydroxychloroquine and without any major risk factors.

Multiple sources of literature were submitted for consideration of posterior SCODI for advanced (severe) stage glaucoma and anterior SCODI to examine the structures of the anterior segment of the eye.

In an observational case study, Leite et al (2010) looked at 99 patients with glaucomatous eyes and 47 control patients.  The severity of disease was graded using the visual field index (VFI) from standard automated perimetry. The authors looked to determine if disease severity had any impact on the diagnostic accuracy of OCT. The average VFI for the glaucomatous eyes was 85.5% and for the control eyes was 99.4% indicating very minimal visual field loss. The results show that for those with mild disease (VFI near 100%) the sensitivity of OCT was 47% and the specificity was 95%.  For those patients with a VFI of 70%, the sensitivity increased to 84% and the specificity was 95%.

Bowd et al (2017) published a study that looked to estimate the measurement floors for spectral-domain optical coherence tomography (SD-OCT) measurements (minimum rim width [MRW], ganglion cell-inner plexiform layer thickness [GC-IPLT], and circumpapillary retinal nerve fiber layer thickness [cpRNFLT]) and compared global change over time in advanced glaucoma eyes. The study included a variability group of 41 eyes of 27 glaucoma patients with moderate to advanced glaucoma to estimate the measurement floors and 87 eyes of 59 patients with advanced to severe glaucoma in a longitudinal group. Average structural loss of MRW, macular GC-IPLT and cpRNFL thickness in the variability group eyes (over 5 weeks of follow- up) and the longitudinal group eyes (over 2 years of follow-up) was presented. The results indicated the mean percentage of image area that did not reach the floor in the baseline images of eyes in the longitudinal group (i.e., the image percentage that changed after 2 years of follow-up) was 19% for MRW, 36% for GC-IPLT and 14% for cpRNFL thickness, indicating that GC-IPLT likely is the most robust measurement for assessing localized change in eyes with advanced glaucoma eyes. Authors concluded that a significant percentage of SD-OCT-measured retinal tissue is spared from the measurement floor in advanced glaucoma eyes. In addition, progressive thinning of the spared tissue is observable well into late-stage disease, particularly when GC-IPLT is the structural parameter measured. These results indicate that optical imaging, particularly SD-OCT imaging, has a place in detecting structural change in eyes with advanced glaucoma.

Belghith et al (2016) did a study is to compare SD-OCT standard structural measures MRW, ganglion cell-inner plexiform layer (GC-IPL), and cpRNF and a new three-dimensional (3D) volume optic nerve head (ONH) change detection method for detecting change over time in severely advanced-glaucoma (open-angle glaucoma [OAG]) patients. The study included three groups of participants. The first group was composed of 35 eyes of 35 advanced-glaucoma patients followed for an average of 3.5 years. The stable glaucoma group consisted of 50 eyes from 27 early-, moderate-, and advanced-glaucoma patients with five serial OCT exams imaged every week for 5 weeks. A third group of 46 eyes from 30 healthy subjects followed for an average of 2.8 years was used to estimate the aging effects. Results suggest that even in very advanced glaucoma, structural loss can be detected in some eyes using standard global structural measures. Specifically, macular GC-IPL had the highest proportion of eyes with detectable change (31%), followed by MRW (11%) and cpRNFL (4%). In addition, the 3D whole-volume Bayesian-kernel detection scheme (BKDS) change method, which does not require extensive retinal layer segmentation, detected change in 37% of eyes. The authors concluded the results suggest that even in very advanced disease, structural change can be detected, and that monitoring macular GC-IPL and 3D whole-volume patients BKDS change shows promise for identifying progression in advanced glaucoma. However, a larger sample of advanced-glaucoma patients with longer follow-up is needed to validate these findings.

In a retrospective case note review, Hau et al (2015) compared AS-OCT with ultrasound B-scan (USB) in evaluating iris and iridociliary body lesions. Patients with other anterior or posterior segment lesions or tumors were excluded from this study. The study included 126 patients (126 eyes), the mean age of the patient group was 57.8, who were imaged with both AS-OCT and USB presenting to the same ocular oncology center over a 2 year period of time. The three most common diagnoses were iris naevi, iris pigment epithelial cysts, and iris melanoma. The aim of the study was to evaluate which imaging modality (AS-OCT vs. USB) provided better visualization and characterization of a large cohort of iris and iridociliary body lesions. High-frequency ultrasound biomicroscopy (UBM) was not included in this study, but was referenced as having some distinct advantages over USB and AS-OCT as well as limitations on use. The results revealed that USB was better than AS-OCT in visualizing all tumor margins, posterior tumor margin, and producing less posterior shadowing. USB was slightly better for resolving the overall tumor and posterior tumor surface, but AS-OCT was better for resolving the anterior and lateral tumor surface. In total, AS-OCT was able to detect more lesions than USB, especially in imaging iris lesions, but it was unable to detect any of the ciliary body lesions.  The authors concluded that AS-OCT is superior to USB for imaging small lesions pertaining to the anterior iris but USB is better for imaging larger iris lesions with posterior or ciliary body extension.

Janssens et al (2016) conducted a systematic review to determine how AS-OC and UBM are in determining tumor margins and tumor depth of conjunctival and corneal tumors and if either of these techniques can provide additional information regarding the diagnosis. Fourteen sources were selected to analyze corneal and conjunctival tumor thickness and internal characteristics and extension in depth and size and shape measured by either of these two noninvasive techniques, AS-OCT or UBM, or a combination of both. The study designs included retrospective analysis, retrospective interventional case series, retrospective non-interventional case series, prospective studies, and unknown study designs. The number of patients in articles using UBM (alone) in conjunctival and corneal tumors totaled 44, the number of patients in articles using AS-OCT (alone) in conjunctival and corneal tumors totaled 211 (212 eyes), and the number of patients in articles using both UBM and AS-OCT in conjunctival and corneal tumors totaled 235 (238 tumors). The results show that both AS-OCT and UBM imaging techniques provide useful information about the internal features, extension, size, and shape of tumors. There is not enough evidence on the advantages and disadvantages of AS-OCT and UBM in certain tumor types. The authors concluded that more comparative studies are needed to investigate which imaging technique is most suitable for a certain tumor type.

Analysis of Evidence

The clinical utility of SCODI has been established and validated in evidence-based guidelines and literature for early detection of glaucomatous damage to the retinal nerve fiber layer or optic disc, differentiation and diagnosis of other disorders of the optic nerve as well as monitoring for progressive optic neuropathy, monitoring retinal conditions, and drug-related ocular toxicity.

A number of studies have been published to evaluate the usefulness of posterior OCT for individuals with advanced glaucomatous damage as well as the potential applications of anterior segment OCT (AS-OCT and SD-OCT with anterior segment imaging capabilities) to image and provide measurements of anterior segment structures in a number of clinical situations. Overall, these studies have small sample sizes, relatively limited follow-up, and no documentation of improved health outcomes in the Medicare population. Some of the studies have populations that would not be generalizable to the Medicare population.

Compliance with the provisions in this LCD may be monitored and addressed through post payment data analysis and subsequent medical review audits.

History/Background and/or General Information

Glaucoma

Glaucoma is a leading cause of blindness, and a disease for which treatment methods clearly are available and in common use. Scanning computerized ophthalmic diagnostic imaging (SCODI) allows for early detection of glaucomatous damage to the nerve fiber layer or optic nerve of the eye. It is the goal of these diagnostic imaging tests to discriminate among patients with normal intraocular pressure (IOP) who have glaucoma, patients with elevated IOP who have glaucoma, and patients with elevated IOP who do not have glaucoma. These tests can also provide precise methods of observation of the optic nerve head and can more accurately reveal subtle glaucomatous changes over the course of follow-up exams than visual field and/or disc photos. This can allow earlier and more efficient treatment of the disease process. The severity of glaucoma damage can be estimated as mild, moderate, severe, or indeterminate.

Retinal Disorders

Retinal disorders are the most common causes of severe and permanent vision loss. SCODI is a valuable tool for the evaluation and treatment of patients with retinal disease, especially macular abnormalities. SCODI is able to detail the microscopic anatomy of the retina and the vitreo-retinal interface. SCODI is useful to measure the effectiveness of therapy, in determining the need for ongoing therapy or cessation of therapy.

The retina is a complex tissue in the back of the eye that contains specialized photoreceptor cells called rods and cones. The photoreceptors connect to a network of nerve cells for the local processing of visual information. This information is sent to the brain for decoding into a visual image. The adjacent retinal pigment epithelium (RPE) supports many of the retina’s metabolic functions.

The retina is susceptible to a variety of diseases, including age-related macular degeneration (AMD), diabetic retinopathy (DR), retinitis pigmentosa (RP) and other inherited retinal degenerations, uveitis, retinal detachment, and eye cancers. Each of these can lead to visual loss or complete blindness.

The leading cause of visual loss among elderly persons is AMD, which has an increasingly important social and economic impact in the United States. As the size of the elderly population increases in this country, AMD will become a more prevalent cause of blindness than both DR and glaucoma combined.

DR is also a major cause of blindness. In the proliferative stage of the disease, newly formed, abnormal blood vessels can break through the retinal surface and hemorrhage into the normally transparent, gelatin-like vitreous in the middle of the eye. Scar tissue may subsequently form and pull the retina away from the back of the eye, causing a retinal detachment to occur.

Rare inherited retinal degenerations, typified by RP, result in the destruction of photoreceptor cells and the RPE.

Clinical evidence has shown that long-term use of chloroquine (CQ) and/or hydroxychloroquine (HCQ) can lead to irreversible retinal toxicity. SCODI may be indicated to provide monitoring of patients for the development of retinopathy during long-term therapy.

SCODI Techniques

There are several forms of SCODI tests that currently exist. SCODI testing includes scanning laser polarimetry, optical coherence tomography (OCT), and confocal scanning laser ophthalmoscopy (CSLO). These testing devices use videographic digitized images to make quantitative topographic measurements of the optic nerve head and surrounding retina. Although these techniques are different, their objective is the same. These methods are described below:

• Scanning Laser Polarimetry (SLP)

The retinal nerve fiber layer (RNFL) is birefringent, causing a change in the state of polarization of a laser beam as it passes. A 780-nm diode laser is used to illuminate the optic nerve. The polarization state of the light emerging from the eye is then evaluated and correlated with RNFL thickness. Unlike confocal scanning laser ophthalmoscopy (CSLO), SLP can directly measure the thickness of the RNFL. GDx® is a common example of a scanning laser polarimeter. GDx® contains a normative database and statistical software package to allow comparison to age-matched normal subjects of the same ethnic origin. The advantages of this system are that images can be obtained without pupil dilation, and evaluation can be done in about 10 minutes. Current instruments have added enhanced and variable corneal compensation technology to account for corneal polarization.

• Optical Coherence Tomography (OCT)

OCT uses near-infrared light to provide direct cross-sectional measurement of the retinal nerve fiber layer. The principals employed are similar to those used in B-mode ultrasound except light, not sound, is used to produce the 3-dimensional images. The light source can be directed into the eye through a conventional slit-lamp biomicroscope and focused onto the retina through a typical 78-diopter lens. This system requires dilation of the patient’s pupil.

• Confocal Scanning Laser Ophthalmoscopy (CSLO)

CSLO is a laser-based image acquisition technique, which is intended to improve the quality of the examination compared to standard ophthalmologic examination. A laser is scanned across the retina along with a detector system. Only a single spot on the retina is illuminated at any time, resulting in a high-contrast image of great reproducibility that can be used to estimate the thickness of the RNFL. In addition, this technique does not require maximal mydriasis, which may be a problem in patients with glaucoma. The Heidelberg Retinal Tomograph is probably the most common example of this technology.

Covered Indications

Anterior segment SCODI will be considered medically reasonable and necessary for evaluation of specified forms of glaucoma and certain disorders of the cornea, iris and ciliary body.

Posterior segment SCODI will be considered medically reasonable and necessary under the following circumstances:

1. For diagnosis and management of a patient who has mild, moderate, severe, or indeterminate stage glaucoma or who is suspected of having glaucoma.

2. Monitoring patients being treated with chloroquine (CQ) and/or hydroxychloroquine (HCQ) for the development of retinopathy.

3. The evaluation and treatment of patients with conditions affecting the optic nerve (e.g., optic neuropathy) or retinal disease (e.g., macular degeneration, diabetic retinopathy) and in the evaluation and treatment of certain macular abnormalities (e.g., macular edema, atrophy associated with degenerative retinal diseases).

Limitations

The following are considered not medically reasonable and necessary:

1. SCODI is usually not medically reasonable and necessary when performed to provide additional confirmatory information regarding a diagnosis which has already been determined. Documentation should support that the SCODI test result was used for establishing a diagnosis, establishing a baseline prior to treatment, or for monitoring purposes.

2. Fundus photography and posterior segment SCODI performed on the same eye on the same day are generally mutually exclusive of one another (National Correct Coding Initiative (NCCI) Policy Manual for Medicare Services). The provider is not precluded from performing both on the same eye on the same day when each service is necessary to evaluate and treat the patient. The medical record should clearly document the medical necessity of each service. Frequent reporting of these services together may trigger focused medical review.

3. Screening (patient without signs or symptoms) for any condition is not medically reasonable and necessary.

Place of Services (POS)

For additional information on services performed in an Independent Diagnostic Testing Facility (IDTF), please refer to Local Coverage Determination (LCD) L33910 Independent Diagnostic Testing Facility (IDTF).

For frequency limitations, please refer to the Utilization Guidelines section below.

Notice: Services performed for any given diagnosis must meet all of the indications and limitations stated in this policy, the general requirements for medical necessity as stated in CMS payment policy manuals, any and all existing CMS national coverage determinations, and all Medicare payment rules.