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DESCRIPTIONTranspupillary thermotherapy (TTT) is a technique in which low level heat is delivered through the pupil using a modified diode laser. TTT is designed to gently heat subfoveal choroidal lesions while limiting damage to the overlying retinal pigment epithelium.
Choroidal neovascularization (CNV) is a common cause of adult-onset blindness, most commonly associated with age-related macular degeneration (AMD). In its earliest stages, AMD is characterized by minimal visual impairment and the presence of large drusen and other pigmentary abnormalities on ophthalmoscopic examination. As AMD progresses, 2 distinctively different forms of degeneration may be observed. The first, called the atrophic, areolar or dry form, evolves slowly. Atrophic AMD is the most common form of degeneration and is often a precursor of the second form, the more devastating exudative neovascular form, also referred to as disciform or wet degeneration. The wet form is distinguished from the atrophic form by serous or hemorrhagic detachment of the retinal pigment epithelium and the development of choroidal neovascularization (CNV), sometimes called neovascular membranes. Risk of developing severe irreversible loss of vision is greatly increased by the presence of CNV.
The pattern of CNV, as revealed by fluorescein or indocyanine angiography, is further categorized as classic or occult. For example, classic CNV appears as an initial lacy pattern of hyperfluorescence followed by more irregular patterns as the dye leaks into the subretinal space. Occult CNV lacks the characteristic angiographic pattern, eitherdue to the opacity of coexisting subretinal hemorrhage or especially in CNV associated with AMD, by a tendency for epithelial cells to prliferate and partially or completely surround the new vessels. Interestingly, lesions consisting only of classic CNV carry a worse visual prognosis than those composed of only occult CNV, suggesting that the proliferative response that obscures new vessels may also favorably alter the clinical course of AMD.
There is ongoing research interest in the use of transpupillary thermotherapy to treat subfoveal choroidal neovascularization with an “occult” angiographic pattern. TTT is a technique in which heat is delivered to the choroid and retinal pigment epithelium through the pupil using a modified diode laser. This laser technique contrasts with the laser used in standard photocoagulation therapy, in that TTT uses a lower power laser for more prolonged periods of time and is designed to gently heat the choroidal lesion, thus limiting damage to the overlying retinal pigment epithelium.
Other Treatments for CNV Secondary to AMD
Other available therapeutic options for AMD not addressed in this policy include photodynamic therapy, which is addressed in the Photodynamic Therapy for Subfoveal Choroidal Neovascularization (CNV) medical policy, and vascular endothelial growth factor (VEGF) antagonists or angiostatics. These may be administered alone or in combination. Angiostatic agents target various points in the pathway leading to new blood vessel formation (angiogenesis): messenger RNA, vascular endothelial growth factors (VEGFs), and endothelial cell proliferation, migration, and proteolysis. Pegaptanib (Macugen®, Eyetech and Pfizer) and ranibizumab (Lucentis™, Genentech) are presently the only angiostatic drugs approved by the U.S. Food and Drug Administration (FDA) for use in AMD. Pegaptanib and ranibizumab bind extracellular VEGF to inhibit the angiogenesis pathway and are administered by intravitreous injections every 4–6 weeks. Bevacizumab (Avastin, Genentech) has been used off label to treat AMD. It is derived from the same murine monoclonal antibody precursor as ranibizumab and is approved by the FDA for the treatment of metastatic cancer of the colon or rectum. Photodynamic therapy has also been used with success in treating subfoveal CNV; the treatment has shown the greatest success in treating patients with classic CNV (as opposed to occult CNV), as defined angiographically. Photodynamic therapy as a treatment of CNV uses a nonthermal laser designed to activate verteporfin, the photosensitizing agent. Laser photocoagulation has been used to treat CNV; however, patients with subfoveal lesions are generally not candidates for this treatment due to the risk of an immediate reduction in central vision, outweighing any treatment advantage.
Central Serous Chorioretinopathy (CSC)
CSC is the fourth most common retinopathy after AMD, diabetic retinopathy, and branch retinal vein occlusion. CSC refers to an idiopathic disease in which there is a serous detachment of the macula due to leakage of fluid from the choriocapillaris through the retinal pigment epithelium. CSC can be divided into acute, recurrent, and chronic conditions. Usually, serous retinal detachments have spontaneous resolution with recovery of visual function; however, a subset of patients may experience permanent deterioration of visual function attributable to chronic CSC or multiple recurrences of CSC. The pathogenesis of CSC is believed to be ischemia and inflammation, which lead to abnormal permeability of the inner choroid and elevation of the retinal pigment epithelium, causing serous epithelial detachments. The separated retinal pigment epithelium can then undergo tiny rips (blowouts) with a break in continuity. The change in permeability of the retinal pigment epithelium results in focal leakage and retinal detachment. Neovascularization can occur as a secondary complication. In about 90% of cases, CSC resolves spontaneously with detachment resolution within 3 months. The traditional management of acute CSC is observation. Recurring or chronic CSC can be treated with focal laser photocoagulation if the leaks are extrafoveal. Although laser may shorten the duration of symptoms, it does not have any impact on the final vision or the recurrence rate of CSC. In addition, laser photocoagulation causes collateral damage creating symptomatic scotomas and a risk of triggering secondary CNV. Photodynamic therapy is not a standard treatment for CSC due to complications that may include CNV, although low-fluence PDT is being evaluated.
Other Choroidal Neovascular Conditions
Other choroidal neovascular conditions include pathologic myopia, presumed ocular histoplasmosis syndrome, angioid streaks, idiopathic CNV, uveitis, choroidal rupture or trauma, and chorioretinal scars. Treatments that have been evaluated for CNV not related to AMD include submacular surgery, laser photocoagulation, and PDT. Efficacy of these treatment modalities is limited.
POLICYTranspupillary thermotherapy is considered investigational as a treatment of choroidal neovascularization secondary to ocular conditions, including but not limited to age-related macular degeneration.
POLICY EXCEPTIONSFederal Employee Program (FEP) may dictate that all FDA-approved devices, drugs or biologics may not be considered investigational and thus these devices may be assessed only on the basis of their medical necessity.
POLICY GUIDELINESInvestigative service is defined as the use of any treatment procedure, facility, equipment, drug, device, or supply not yet recognized by certifying boards and/or approving or licensing agencies or published peer review criteria as standard, effective medical practice for the treatment of the condition being treated and as such therefore is not considered medically necessary.
The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.
POLICY HISTORY3/31/2005: Approved by Medical Policy Advisory Committee (MPAC)
6/6/2005: Code Reference section completed
3/17/2006: Policy reviewed, no changes
5/21/2007: Policy reviewed, no changes
6/30/2008: Policy reviewed, description section rewritten, policy unchanged
04/06/2010: Policy description updated regarding other available therapeutic options for age-related macular degeneration. Policy statement unchanged. FEP verbiage added to the Policy Exceptions section.
04/20/2011: Policy reviewed; no changes.
03/27/2012: Policy description updated; policy statement unchanged. Added 67299 to the Code Reference section.
07/18/2013: Policy title changed from "Transpupillary Thermotherapy for Treatment of Choroidal Neovascularization" to "Transpupillary Thermotherapy for Treatment of Choroidal Neovascular Conditions" to reflect the expanded scope of the policy. Policy description updated regarding Central Serous Chorioretinopathy and Other Choroidal Neovascular Conditions. Added "secondary to ocular conditions, including but not limited to age-related macular degeneration" to the policy statement. Deleted outdated references from the Sources section. Removed deleted CPT code 0016T from the Code Reference section. Added ICD-9 procedure code 14.29 to the Code Reference section.
SOURCE(S)Blue Cross Blue Shield Association policy # 9.03.10
CODE REFERENCEThis may not be a comprehensive list of procedure codes applicable to this policy.