Summary Of Evidence

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Analysis of Evidence

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Background:

Scanning computerized ophthalmic diagnostic imaging (SCODI) is a noninvasive, noncontact imaging technique that produces high resolution images of ocular structures. These high resolution images are used to provide qualitative and quantitative data about the structural or physiologic properties of structures in the anterior and posterior segment that have been validated as clinically useful in monitoring progression, resolution, or response to treatment of various ocular conditions involving the retina and optic nerve over time.

Scanning computerized ophthalmic diagnostic imaging makes use of 3 distinct technologies to generate quantitative data:

• confocal laser scanning ophthalmoscopy (CSLO)
• scanning laser polarimetry (SLO)
• optical coherence tomography (OCT)

Examples of CSLO and SLO devices currently in use in clinical practice include the Heidelberg Laser Tomographic Scanner, Heidelberg Retinal Tomography (HRT), the GDx Nerve Fiber Analysis System, and the Retinal Thickness Analyzer (RTA). OCT is available from a number of manufacturers using 1 of 2 basic platforms, time domain (TD-OCT), such as the Visante anterior segment OCT, and the more widely used spectral, or Fourier, domain (SD/FD-OCT), such as the Spectralis, RTVue, Cirrus, and iVue.

Although these techniques are different, their objective is the same. Medicare will consider SCODI medically reasonable and necessary in evaluating disorders of the anterior and posterior segment as documented in this local coverage determination (LCD).

Posterior Segment

Glaucoma is the second leading cause of blindness worldwide, and a disease for which effective treatment to slow or prevent progressive vision loss is available. However, glaucoma is diagnostically challenging and the majority of patients are asymptomatic early in the course of disease when the disease is most amenable to treatment. At the time of diagnosis, approximately 10-39% of patients have irrecoverable vision loss from advanced glaucoma. Elevated intraocular pressure is a clear risk factor for glaucoma, but over 40% of cases have pressures in the normal range, while many other patients with abnormally high pressures do not suffer glaucomatous damage. Structural changes in the optic disc may not appear until a significant functional deficit (visual field loss) has occurred.

There is no single diagnostic test that can be used exclusively to diagnose and monitor glaucoma. Diagnosis of glaucoma is made using an assemblage of data from tests that provide complementary assessments of the functional and structural status of the optic nerve. This often includes a comprehensive history and eye exam including visual acuity measurement, pupillary examination, intraocular pressure measurement, gonioscopy, anterior segment exam, fundoscopy, optic disc and retinal nerve fiber layer examination; and often confirmatory diagnostic tests including central corneal thickness measurement, visual field evaluation (preferably using automated perimetry), and quantitative imaging of the optic nerve head and retinal nerve fiber layer with stereoscopic disc photographs and SCODI.

SCODI allows for early detection of glaucomatous damage to the retinal nerve fiber layer or optic disc, and has demonstrated clinical utility in facilitating earlier diagnosis and treatment, as well as monitoring for progression and response to treatment.

SCODI also allows for differentiation and diagnosis of other disorders of the optic nerve, as well as monitoring for progressive optic neuropathy and response to treatment in a number of neuro-ophthalmologic conditions.

Retinal disorders are among the most common causes of severe and permanent vision loss. SCODI is an invaluable tool for the evaluation and treatment of patients with retinal disease, particularly when there is macular involvement. SCODI is able to detail the microscopic anatomy of the retina, subretina, and vitreoretinal interface and provide information that has demonstrated evidence of superiority to other available techniques in a number of clinical studies.

SCODI has demonstrated clinical utility in monitoring patients with retinal diseases for progression, which is critical for judging a response to or need for treatment of a number of retinal conditions.

SCODI has been validated for use in ongoing screening for drug-related ocular toxicity, due to its ability to detect early photoreceptor damage in patients taking certain high-risk drugs. The use of SCODI should be performed according to the most current recommended guidelines. The current recommendations for monitoring patients taking chloroquine or hydroxychloroquine include 1) a baseline exam within the 1st year of commencement which should include a SD-OCT if any macular abnormalities are present, and, 2) annual screening beginning at the 5th year of exposure in patients who are on a dose <5 mg/kg real weight and who lack other major risk factors. The presence of major risk factors or a dosage exceeding 5 mg/kg real weight may necessitate earlier and more frequent screening intervals.

Anterior Segment

There are numerous reports in the literature detailing the potential applications of anterior segment optical coherence tomography (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. The current literature consists primarily of qualitative and quantitative imaging and detection capabilities, though there remains a lack of consensus on the sensitivity, specificity, and predictive value of AS-OCT in the vast majority of anterior segment applications and no endorsement of its use over gonioscopy or ultrasound biomicroscopy.

The strongest evidence in support of the clinical utility of AS-OCT lies in its ability to image the structures of the anterior chamber angle, particularly in narrow angles. Current recommended practice patterns by the American Academy of Ophthalmology endorse gonioscopy as the preferred means of performing evaluation of the anterior chamber angle. Although there remains insufficient evidence to endorse AS-OCT as a substitute for gonioscopy, AS-OCT is a recommended option in cases where angle closure is suspected, and the angle anatomy is not conducive to gonioscopic assessment.

Indications and Limitations:

SCODI – Anterior Segment

SCODI, anterior segment, with interpretation and report.

AS-OCT is considered reasonable and necessary when ordered for the evaluation of narrow angle, suspected narrow angle, and mixed mechanism glaucoma:

• In patients who are unable to undergo gonioscopy due to cognitive or physical limitations

• When anatomic features, corneal opacity, or corneal edema preclude gonioscopic visualization

Indications other than those stipulated in this LCD are considered investigational and are not covered.

SCODI is not covered for screening.

SCODI is not covered in the absence of an indication.

It is expected that no more than 2 AS-OCT tests per year would be indicated in evaluating patients with a diagnosis of angle closure suspect, narrow angles, angle closure, and mixed mechanism glaucoma without a significant change in clinical status.

It is expected that no more than 1  AS-OCT test per 3 years would be indicated in evaluating patients with all forms of open angle glaucoma including glaucoma suspect, ocular hypertension, secondary glaucoma, and congenital glaucoma.

SCODI – Optic Nerve

 SCODI, posterior segment, with interpretation and report, unilateral or bilateral nerve.

SCODI of the optic disc is considered reasonable and necessary when ordered to:

• Aid in the early diagnosis of glaucoma and monitor for progression and response to treatment

• Monitor glaucoma suspect patients for evidence of glaucomatous change

• Detect further loss of optic nerve or retinal nerve fiber layer tissue to aid in monitoring for progression in advanced optic nerve damage and advanced visual field loss

• Differentiate when there is a discrepancy between the clinical appearance of the optic nerve and the visual field

• Provide additional information to facilitate diagnosis and management when visual field results are insufficient or cannot be performed due to visual, mental, physical, or age limitations of the patient

• Differentiate causes of other optic nerve disorders when a diagnosis is in doubt

• Aid in the diagnosis and management of other optic nerve disorders and neuro-ophthalmologic diseases involving changes in the optic nerve head and retinal nerve fiber layer

SCODI is not covered when used for screening.

SCODI is not covered in the absence of an indication.

It is expected that no more than 1 SCODI test per year would be indicated in monitoring patients with glaucoma suspect without a significant change in clinical status.

It is expected that no more than 2 SCODI tests per year would be indicated in monitoring patients with progressive optic neuropathies, including glaucoma (mild, moderate, severe, and indeterminate) without a significant change in clinical status.

Advancements in SCODI technologies have increased the utility of these devices in both the diagnosis of glaucoma and detection of glaucomatous progression. Hardware and software limitations can impact the reliability of these tests in more advanced cases of glaucoma, particularly once the floor effect is reached, whereby the ability to discern and measure thickness of the remaining neural tissue limits the ability to detect progression. The use of SCODI in advanced glaucoma is covered, provided the hardware and software utilized continues to provide clinically meaningful measurements that allow for the detection of progression.

SCODI – Retina

SCODI, posterior segment, with interpretation and report, unilateral or bilateral. 

SCODI of the retina is considered reasonable and necessary when ordered to:

• Aid in the diagnosis and management of retinal conditions which involve changes in the subretinal, intraretinal, and vitreoretinal relationships

• Monitor for progression or resolution of conditions in order to determine the need for or response to treatment

• Monitor for evidence of ocular toxicity in patients taking high risk drugs with a known potential for causing toxic retinopathy

SCODI is not covered when used for screening.

SCODI is not covered in the absence of an indication.

SCODI should only be performed at clinically reasonable intervals (i.e., consistent with a noted change in clinical status or after sufficient time has elapsed to assess for progression or response to treatment). It is generally expected that conditions requiring more aggressive treatment and monitoring due to changing clinical status or treatment interventions will generally not require SCODI testing more than 1 per month.

Current recommendations for monitoring patients taking chloroquine or hydroxychloroquine, who are on a dose <5 mg/kg real weight, who lack other major risk factors are recommended to undergo screening beginning at the 5th year of exposure and annually thereafter. The presence of major risk factors or a dosage exceeding 5 mg/kg real weight may necessitate earlier and more frequent screening intervals.