Intrachoroidal Dye Leakage in Indocyanine Green Fundus Angiography after Experimental Commotio Retinae

Computer Assisted Image Analysis Using the Subtraction Method in Indocyanine Green Angiography

The choroidal vessels are three dimensionally distributed and very complex in their patterns. They often appear to be overlaid in indocyanine green (ICG) angiograms so it is harder to analyze ICG angiography than fluorescein angiography. When an earlier frame is subtracted from a later frame in a sequence of angiograms, the fluorescence which has increased during the time between the two frames can theoretically be demonstrated.

We applied computer-assisted image subtraction methods in selected clinical cases of directly acquired digital ICG angiography to demonstrate how this method works. We used software already installed in an IMAGEnet computer system (Topcon) for image subtraction. We applied the subtraction technique in 18 cases with various diseases. When two images with a time difference of several seconds were subtracted, filling of the choriocapillaris, the neovascularization or the pathological vessels could be observed. When the images had a time difference of several minutes, intrachoroidal dye leakage could be seen more clearly. This method is very helpful for analyzing pathological changes in ICG angiography in clinical cases, when two images are selected appropriately.

Indocyanine green angiographic features of choroidal rupture and choroidal vascular injury after contusion ocular injury

PURPOSE

To report features of choroidal rupture and choroidal vascular injury after contusion ocular injury on indocyanine green angiography.

METHODS

In a prospective study, nine patients (nine eyes) with choroidal rupture after ocular contusion underwent initial fluorescein angiography and indocyanine green angiography within 19 days after trauma. Eyes that had a distinct abnormality of the retinal pigment epithelium were excluded from this study. Subtraction indocyanine green angiography was also performed. Follow-up fluorescein angiographic and indocyanine green angiographic findings were also studied.

RESULTS

Initial ophthalmoscopic examination revealed subretinal hemorrhage in all nine eyes. In five of the nine eyes, choroidal rupture was not seen on initial ophthalmoscopic or fluorescein angiographic examination because it was hidden beneath the subretinal hemorrhage, but it was detected on subsequent examinations. In the remaining four eyes, choroidal rupture was observed by ophthalmoscopy at the time of initial examination, and these eyes exhibited hyperfluorescent streaks on fluorescein angiography in the region of the subretinal hemorrhage. On initial indocyanine green angiography of all nine eyes, observed hypofluorescent streaks became more obvious with time. For each eye, there were more hypofluorescent streaks on indocyanine green angiography than hyperfluorescent streaks on fluorescein angiography. In one eye, the location of indocyanine green leakage nearly coincided with the location of a hyperfluorescent streak on fluorescein angiography. In this case, crescentic streaks of hypofluorescence were seen on the temporal side of the subretinal hemorrhage on indocyanine green angiography, although choroidal rupture was not observed in that region by ophthalmoscopy or fluorescein angiography. In two of the nine eyes, indocyanine green angiography and the subtraction technique demonstrated disturbance of flow into choroidal vessels, especially at the choroidal rupture site.

CONCLUSION

After ocular contusion injury, various features of choroidal rupture and choroidal vascular injury were observed on indocyanine green angiography. This technique may contribute to the diagnosis of choroidal rupture and to the understanding of the clinical course after injury.

Choroidopathy after blunt trauma to the eye: a fluorescein and indocyanine green angiographic study

PURPOSE

To describe the uses of fluorescein angiography and indocyanine green angiography in highlighting traumatic choroidopathy.

METHODS

In a prospective study, 21 patients (21 eyes) who presented with traumatic retinal opacity ophthalmoscopically underwent fluorescein angiography and indocyanine green angiography. With indocyanine green angiography, the subtraction method was used for detailed examination.

RESULTS

In 11 of 21 eyes, fluorescein angiography showed no abnormalities. On indocyanine green angiography, delayed filling in the choroid was found locally in nine of these 11 eyes. Delayed filling of the choroidal veins was clearly visualized by the subtraction method. In six eyes, intrachoroidal indocyanine green leakage around the choroidal vessels, including vortex veins, was found. In the remaining 10 of the 21 eyes, fluorescein angiography showed fluorescein leakage or a salt-and-pepper appearance in the region of retinal opacity. On indocyanine green angiography, a triangular-shaped area of delayed filling of the choroidal arteries was observed in four eyes. Delayed filling of the choroidal veins was visualized in all 10 eyes, intrachoroidal indocyanine green leakage was found in eight, and dilation and/or narrowing of the choroidal veins and changes in choroidal vasculature were visualized in five eyes. Furthermore, in regions with fluorescein leakage, indocyanine green leakage or hypofluorescence was observed, suggesting damage to the choriocapillaris.

CONCLUSION

Indocyanine green angiography allows the analysis of various degrees of choroidal vascular damage. Because the choroidal circulation nourishes the outer retinal layer, traumatic choroidopathy may play a role in the prognosis for visual recovery in eyes affected by contusion retinal opacities.

Angiographic abnormalities of experimental autoimmune uveoretinitis

PURPOSE

Experimental autoimmune uveoretinitis (EAU) is an invaluable animal model for studying inflammatory eye disease in humans. Indocyanine green (ICG) is a fluorescent dye that can be used to image both retinal and choroidal vessels. This study was performed to examined the retinal and choroidal vascular abnormalities of a rat model of EAU using ICG and fluorescein as the contrast media to assess the suitability of this model for studying ICG angiographic abnormalities in inflammatory eye disease in humans.

METHODS

Twenty-six black-hooded Lister rats were inoculated with bovine retinal S-antigen plus adjuvant with or without Bordetella pertussis antigen. Fluorescein and ICG angiograms were performed at different stages of clinical disease with a scanning laser ophthalmoscope.

RESULTS

EAU was more severe and primarily choroidal disease in rats given Bordetella pertussis, but no animals showed evidence of dye leakage from large choroidal vessels. There was frank leakage of indocyanine green from retinal vessels. Leakage of both fluorescein and ICG retinal vessels largely correlated with disease activity. Retinal pigment epithelial lesions either corresponded to areas of hypofluorescence on the ICG angiogram alone or were represented by areas of ICG hyperfluorescence that had overlying areas of fluorescein leakage from retinal capillaries.

CONCLUSIONS

This study has demonstrated the vascular abnormalities of this model of EAU using ICG and fluorescein as the contrast media. The suitability of this method for studying ICG angiographic abnormalities in inflammatory eye disease in humans is encouraging.

Indocyanine green angiography in multiple evanescent white-dot syndrome

Using indocyanine green angiography we examined two patients with multiple evanescent white-dot syndrome. Both patients had unilateral loss of vision and a fundus appearance typical of multiple evanescent white-dot syndrome. Fluorescein angiography in both patients disclosed a patchy hyperfluorescent pattern at the level of the retinal pigment epithelium. Using indocyanine green angiography, we observed multiple deep, small, round hypofluorescent lesions that appeared early and persisted into the late phases. The spots appeared to block the underlying choroidal pattern. These hypofluorescent spots were clearly visible and present throughout the posterior pole. Many more spots were seen on indocyanine green angiography than were visible by clinical examination or angiography. After follow-up examinations, there was a rapid resolution of the spots over four to six weeks with return of vision. Our findings show that indocyanine green angiography can be a valuable tool in the recognition and further understanding of multiple evanescent white-dot syndrome.