Choroidoretinal vascular anastomoses after blunt trauma to the eye

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.

Optimal conditions required for the creation of an iatrogenic chorioretinal venous anastomosis in the dog using argon green laser photocoagulation

We have previously reported iatrogenic retinal to choroidal vein anastomosis, developed as a potential method of by-passing the site of obstruction to venous outflow in retinal venous occlusion in dogs (1), and in rats (2). In order to minimise tissue damage to the retina and choroid and increase the rate of success in these experiments, we investigated in the dog model the factors that would promote an anastomosis and compare the effects of three different power levels. A small spot size (50 microns) argon green laser beam of 514 nm at power levels of 0.5w, 1.5w and 2.5w were used. Spaced serial sections from each lesion were examined by light and by transmission electron microscopy. Morphometric measurements of the corresponding retinal pigment epithelium (RPE)/glial scar was computed using IBMPC digitising pad and sigma scan software and the extent of tissue damage at the different power levels assessed. At the lowest power level of 0.5w the damage to the retina was mild and there was an absence of anastomosis formation. At the 1.5w power level an anastomosis formed in 40% of the lesions. At the highest power level of 2.5w a 71% rate of success was obtained however, the damage to the retina tended to be severe. The results of this study also indicate that disruption of Bruch's membrane and vein rupture at the time of irradiation are essential for anastomosis formation, which may be further enhanced by necrotic tissue, retinal pigment epithelial and glial scar formation and inflammation. These findings are useful in establishing optimal conditions for the creation of a chorioretinal venous anastomosis, for consideration in human trials.

Significance of Bruch's membrane in the creation of iatrogenic chorioretinal venous anastomosis

Iatrogenic retinal to choroidal vein anastomoses, as a method of bypassing retinal venous occlusions has been reported in dogs in which Bruch's membrane is poorly formed. In order to determine whether chorioretinal venous anastomoses can be induced in an animal with a Bruch's membrane that is well developed as in humans, pigmented rats were chosen. A high intensity, small spot size argon green laser beam of 514 nm was used to induce the anastomosis. Three out of 5 rat eyes developed a retinal vein to choroidal vein anastomosis. The success rate of iatrogenic retinal to choroidal vein anastomoses in the rat was comparable to that obtained in the dog. This study suggests that Bruch's membrane was not significant in the creation of an iatrogenic chorioretinal venous anastomosis.

Choroidal rupture and optic atrophy

The association between post-traumatic optic disc pallor and traumatic choroidal rupture is poorly understood. To further define this relationship, nine cases of indirect traumatic choroidal rupture and post-traumatic optic disc pallor were compared with cases of indirect choroidal rupture without disc pallor in terms of severity of ocular injury, fundus findings, and visual outcome. The type and severity of the injury did not appear to influence the risk of optic disc pallor. Optic disc pallor was associated with a slightly poorer long term visual acuity than eyes without pallor (p = 0.059). The presence of a relative afferent pupillary defect was strongly associated with optic disc pallor (p = 0.016). Peripapillary retinal pigment epithelial abnormalities were a common finding, suggesting peripapillary trauma as a cause for optic disc pallor.

Induced chorioretinal venous anastomosis in experimental retinal branch vein occlusion

Iatrogenic retinal vein to choroidal vein anastomoses were created using laser photocoagulation in six of seven dog eyes in which a partial branch retinal vein occlusion had previously been created photochemically. A similar attempt to create an anastomosis was made in six control eyes in which no branch vein occlusion was present. In the eyes in which a branch retinal vein had been created, a venous chorioretinal anastomosis appeared to be present by 3 to 6 weeks. In three control eyes similar venous anastomosis was created; however this took 6 to 8 weeks to develop and was of much smaller calibre than the one that developed in the presence of a partial branch retinal vein occlusion. No adverse complications were noted in the period of the study (3 months). This study demonstrates that chorioretinal venous anastomoses can be created and may be of use in the treatment of partial retinal vein occlusions that show signs of progression.

Complications of endodrainage retinotomies created during vitreous surgery for complicated retinal detachment

The authors report nine cases of endodrainage retinotomy site complications that occurred after vitreous surgery for complicated retinal detachments (RDs). Postoperative subretinal neovascularization developed in four eyes at the retinotomy drainage site. In two eyes, postoperative proliferation at a posteriorly placed endodrainage site created traction macular detachments. Redetachment due to retinotomy opening caused by postoperative drainage site proliferation developed in three eyes. The retinas of all nine eyes were eventually reattached, and vision improved from the preoperative level. These complications are related to retinal pigment epithelium and/or Bruch's membrane damage during internal subretinal fluid drainage and retinotomy endolaser photocoagulation. Careful evaluation of extrusion instruments, drainage techniques, retinotomy placement, and subsequent endolaser treatment is necessary to minimize these complications.

The disciform response: an historical perspective

This paper is a survey of the literature in an attempt to provide the basis for our current understanding of the disciform process. Particular emphasis is placed on its pathogenesis and the role of subretinal neovascularization. No two lesions appear exactly alike because of the many stages and combinations possible. Gass (1967) has delineated the broad spectrum with the many different clinical manifestations of this disease process. Verhoeff and Grossman (1937) provided the histopathologic basis for our understanding of the disciform process. The histologic correlation of the clinical "predisciform" state would seem to offer the most promising information for understanding the pathogenesis of the disciform process (Frank et al. 1973; Green and Key 1977; Kornweig 1967; Sarks 1973 and 1976; Small et al. 1976; Zauberman 1970). It is hoped that this literature review has sufficiently emphasized the inherent deficiencies of strictly clinical studies and the need for an appropriate experimental animal model (Ryan 1979).

Choroidoretinal vascular anastomoses

Three cases of choroidoretinal anastomosis had unusual etiologic and hemodynamic features. In two cases the anastomoses, one caused by ocular histoplasmosis and one by diabetic maculopathy, shunted retinal venous drainage into the choroid. In the third case, the congenital arterial choroidoretinal anastomosis should probably be termed retinochoroidal arteriovenous anastomosis. Prospective photographic and fluorangiographic studies of these patients suggest that our understanding of many basic features of retinal-choroidal circulatory hemodynamics is incomplete.

Congenital bilateral arterial anastomosis between the choroid and peripheral retina

A healthy 26-year-old woman, had a decrease of vision in her left eye caused by a macular pucker, showed deformed retinal vessels, small exudative detachments of the neuroretina, and retinal exudates and hemorrhages in both fundi peripheral to the equator at the 6-o'clock position. Fluorescein angiography and stereoscopic photographs clearly showed an anastomosis of a recurrent ciliary artery with periphral retinal vessels and localized absence of the choriocapillaris under the detached retina in both eyes. The anastomosis probably developed in the last month of fetal life as the result of a localized absence of Bruch's membrane caused by an incomplete coloboma of the choroid that originated during the second month of gestation.

Prospective observation of vascular anastomoses between the retina and choroid in recurrent toxoplasmosis

Prospective angiographic observations demonstrated the formation of both choroidoretinal arteriolar anastomoses as well as retinochoroidal venular anastomoses in the ocular fundus of a young man with recurrent ocular toxoplasmosis.

Chorioretinal vascular anastomoses after perforating trauma to the eye

A 32-year-old white man sustained an ocular injury with a small piece of metal. He had perforation of the retina and choroid, and later developed chorioretinal vascular anastomosis. Disabling complications, such as neovascular growth, serous transudation, or hemorrhages, did not occur within a ten-month follow-up period. Interruption of Bruch's membrane and the retinal pigment epithelium, with approximation of the normally separated vasculatures of the choroid and retina, appears necessary for such anastomoses to occur.