The fundus findings of RCH are usually typical and the diagnosis can be made based solely on clinical examination. Some conditions should be considered in the differential diagnosis. These include Coats’ disease, racemose hemangioma, retinal cavernous hemangioma, retinal macroaneurysm, and vasoproliferative tumor.

7.3.10.1  Coats’ Disease

and subretinal fluid. Important findings that differentiate vasoproliferative tumor from RCH are the absence of prominent feeder vessels, peripheral location in the inferior quadrant, and mean age of presentation at 40 years. In contrast, RCH is more commonly located in the temporal quadrant and midperiphery with a mean age of diagnosis at 25 years.

Coats’ disease is characterized by unilateral retinal telangiectasia and, most commonly, affects young males. In contrast to RCH, vascular abnormality in Coats’ disease is diffuse and prominent feeder vessels are not present.

7.3.10.2  Racemose Hemangioma

Congenital retinal arteriovenous malformation (AVM) (racemose hemangioma, Wyburn-Mason disease) is a congenital condition characterized by dilation and tortuosity of retinal arteries and veins. The dilated vessels resemble the feeder vessels in RCH. However, there are no angiomas present. Additionally, these dilated vessels do not cause exudation.

7.3.10.3  Retinal Cavernous Hemangioma

Retinal cavernous hemangioma is a congenital condition characterized by clusters of small vascular dilatations centered on a retinal vein. Fluorescein angiography shows pooling of the dye within the vascular spaces with layering of cells. In contrast to RCH, it lacks prominent feeder vessels.

7.3.11  Fluorescein Angiography

Of all the ancillary tests available, fluorescein angiography (FA) is the most informative diagnostic tool because of the vascular nature of the tumor. In the arterial phase, fluorescein is evident in the dilated feeder arteriole. The retinal tumor has fine capillary filling that rapidly becomes homogeneous. In the venous phase, the efferent vein becomes prominent while the tumor shows leakage of dye. FA is particularly useful in diagnosing juxtapapillary RCH by revealing the fine vascular pattern on the angiogram. Additionally, FA is helpful in distinguishing afferent arteriole from efferent venule and, therefore, can be an adjunct to planning treatment and assessing therapeutic response.

7.3.12  Indocyanine Green Angiography

Indocyanine green angiography (ICG) is helpful in differentiating choroidal lesions such as choroidal hemangioma and choroidal neovascular membrane from RCH [108]. With retinal vascular supply, RCH is best characterized with FA.

7.3.10.4  Retinal Macroaneurysm

Retinal macroaneurysm is an acquired defect seen in older individuals with hypertension. It presents as an out-pouching of the retinal arteriole frequently associated with subretinal, intraretinal, or vitreous hemorrhage. It is not associated with feeder vessels.

7.3.13  Ultrasonography

Ultrasonography is useful in the presence of opaque media. A-scan is characterized by high internal reflectivity and B-scan shows well-demarcated retinal lesion without choroidal effects.

7.3.10.5  Vasoproliferative Tumor

7.3.14  Magnetic Resonance Imaging

Vasoproliferative tumor appears similar to RCH, as orange red vascular tumors associated with exudation

Magnetic resonance imaging is very useful in detecting associated CNS hemangioma. With the use of

surface coils, contrast agents, and thin orbital sections, RCHs more than 2 mm thick can also be detected. These lesions appear isointense or hyperintense compared to vitreous on T1-weighted images and isointense or hypointense on T2-weighted images. With contrast agent, RCHs show enhancement.

7.3.15  Color Doppler Imaging and

Laser Scanning Tomography

Color doppler imaging and laser scanning tomography can be used to document tumor blood flow [109– 111]. Singh et al demonstrated reduction of blood flow velocity by doppler sonography and decrease in venous vessel diameter using laser scanning tomography in a case treated with plaque radiotherapy.

7.3.16  Treatment

Treatment is based on the patient’s visual potential and the lesion size, location, and associated findings such as the extent of subretinal fluid, evidence of retinal traction. Most commonly, RCH is managed by observation, laser photocoagulation, cryotherapy, plaque radiotherapy, and vitreoretinal surgery. Foreign protein therapy, electrolysis, and diathermy are only of historical interest [112–115].

7.3.17  Observation

RCHs tend to enlarge and cause visual loss. Careful observation is recommended only in reliable patients with nasally located lesions smaller than 500 mm and are not associated with exudation or subretinal fluid. Lesions that have undergone spontaneous regression demonstrate sheathing and absence of prominent feeder vessels [116]. These lesions are inactive and can be observed. The juxtapapillary variant behaves differently from the peripheral type of RCH and can be stable for many years [88]. Treatment should be undertaken only if the vision is reduced or if there is progression as therapy usually causes significant reduction of visual acuity due to adverse effects on the optic nerve and major retinal vessels [89, 91, 92, 117].

7.3.18  Laser Photocoagulation

Laser photocoagulation effectively treats posteriorly located lesions smaller than 4.5 mm. More recently, Argon [113, 116, 118–122], Krypton [117], yellow dye [123], and Diode lasers have all shown excellent treatment results in addition to Xenon arc photocoagulation [124]. Yellow dye and Krypton laser offers a theoretical advantage, because oxyhemoglobin and reduced hemoglobin selectively absorb the yellow wavelength more than the green–blue wavelengths of the Argon laser [116, 118, 119]. Photocoagulation should be applied directly to the tumor, the feeder artery, or both [92, 116, 122, 123]. The spot size, duration, and power vary, but the goal is to achieve light gray uptake over the tumor and partial constriction of the feeder arteriole [118, 119, 123]. Direct photocoagulation of the tumor may cause hemorrhage and exudative retinal detachment [92, 113]. Therefore, some advocate treating feeder artery to reduce blood flow to the tumor [123]. The sequence of treatment varies. Some treat the tumor and feeder artery in the same session while others treat the feeder vessels first, followed by the tumor, and eventually the draining vein [122]. Treatment response is usually evaluated in 4–6 weeks. Larger tumors often require multiple treatment sessions [119, 125]. Subretinal fluid resolution, tumor size reduction, color change from bright red to pale pink, and vessel narrowing are indicative of adequate response to treatment. Complete obliteration of the RCH is not necessary to prevent visual loss from the lesion.

Laser photocoagulation of RCH is associated with retinal or vitreous hemorrhage and ablatio fugax. Direct tumor treatment is associated with smaller scotoma than feeder vessel treatment [122].

7.3.19  Cryotherapy

Along with laser photocoagulation, cryotherapy is the mainstay of treatment for RCH. It is the preferred method of treatment for tumors larger than 3.0 mm, located anteriorly, or associated with subretinal fluid [92, 116, 118]. Cryotherapy is applied transconjunctivally under indirect ophthalmoscopy with a temperature between −60 and −80°C. Two freeze-thaw cycles are applied and thawing is initiated after the ice ball