AN IN VIVO MORPHOLOGIC COMPARISON OF RETINAL NEOVASCULARIZATION IN SICKLE CELL AND DIABETIC RETINOPATHY Francisco A. Folgar, MD, Shantan Reddy, MD, MPH
Purpose: To analyze the in vivo morphology of the sea fan in proliferative sickle cell retinopathy and compare it with the neovascularization in proliferative diabetic retinopathy. Methods: Brief case report of spectral-domain optical coherence tomography imaging of a sea fan in a patient with sickle cell anemia and newly diagnosed proliferative sickle cell retinopathy, and morphologic comparison with spectral-domain optical coherence tomography imaging of a neovascular membrane in a diabetic patient with proliferative diabetic retinopathy. Results: Spectral-domain optical coherence tomography imaging revealed that the sea fan is a thicker caliber preretinal fibrovascular membrane involving primarily the retinal nerve fiber and ganglion cell layers. The diabetic membrane has more vitreous adhesions, and it is more closely intertwined with the retina, involving all the retinal layers down to the outer plexiform layer. Conclusion: Spectral-domain optical coherence tomography imaging identified important in vivo morphologic differences between neovascularization in proliferative sickle cell retinopathy and proliferative diabetic retinopathy. These differences were consistent with previous histological studies and may explain the increased risk of tractional retinal detachment in patients with diabetes. RETINAL CASES & BRIEF REPORTS 6:99–101, 2012
tomography. Here, we report the use of spectraldomain optical coherence tomography (SD-OCT) to analyze the in vivo morphology of the sea fan in PSR and compare it with diabetic neovascularization.
From the Department of Ophthalmology, New York University Langone Medical Center, New York, New York.
T
he classic sea fan of proliferative sickle cell retinopathy (PSR) has been previously studied by fluorescein angiography and histological methods.1,2 Sea fans are neovascular fronds composed of largediameter vessels, arising at the edge of perfused and ischemic retina.3 By contrast, retinal neovascularization in proliferative diabetic retinopathy (PDR) begins as loops or nets of fine vessels lying on the surface of the optic disk or along the arcades in the posterior retina.4 To our knowledge, there are no reports of direct imaging of sea fans by optical coherence
Case Reports Case 1 A 54-year-old man with sickle cell anemia and glaucoma presented for routine examination. Visual acuity was 20/20 in both eyes. Posterior examination revealed stage III sickle cell retinopathy with a sea fan neovascular frond in the temporal periphery of the right eye. Stage II sickle cell retinopathy was present in the left eye. SD-OCT of the sea fan demonstrated a large preretinal fibrovascular membrane arranged in thick cord like vascular channels associated with minimal vitreous traction (Figure 1). The neovascular membrane involved the retinal nerve fiber and ganglion cell layers, while leaving the inner plexiform and inner nuclear layers undisturbed. The right eye was treated with scatter argon laser photocoagulation to the areas of ischemic retina surrounding the sea fan, producing adequate involution and regression of the neovascular vessels.
Neither author has any financial/conflicting interests to disclose. Reprint requests: Francisco A. Folgar, MD, Department of Ophthalmology, New York University Langone Medical Center, 462 First Avenue, 5N-18, New York, NY 10016; e-mail: [email protected]
99
100
RETINAL CASES & BRIEF REPORTS´ 2012 VOLUME 6 NUMBER 1
Fig. 1. SD-OCT of a sea fan neovascular membrane in sickle cell anemia, illustrating the involvement of the retinal nerve fiber and ganglion cell layers, while leaving the inner plexiform and inner nuclear layers undisturbed (arrow).
Case 2 A 46-year-old man with type 2 diabetes mellitus for more than 10 years presented for his first diabetic eye examination. Visual acuity was 20/60 in the right eye and 20/50 in the left eye. Posterior examination revealed PDR in both eyes. SD-OCT of a large neovascular membrane nasal to the right optic nerve revealed a thin delicate fibrovascular membrane that was closely intertwined with the inner retina (Figure 2). The retinal nerve fiber, ganglion cell, inner plexiform, inner nuclear, and outer plexiform layers were all disrupted by the neovascular complex. SD-OCT also demonstrated prominent vitreous adhesions exerting traction on the neovascular membrane/retina complex. Panretinal laser photocoagulation was administered to both eyes over the course of multiple sessions. Direct photocoagulation of neovascular membranes was avoided, and laser spots were faint and spaced further apart in areas of retinal tissue directly surrounding the neovascularization, to avoid complications of vitreous hemorrhage or fibrovascular traction. The neovascularization regressed in both eyes in response to panretinal photocoagulation, and visual acuity remained stable.
Discussion SD-OCT in our two cases identified a number of morphologic differences between neovascularization in PSR and PDR. The relative absence of vitreous
traction in PSR when compared with the diabetic neovascular membrane is consistent with previous histological studies and may explain the increased risk of tractional retinal detachment in patients with diabetes.1,2,5 Furthermore, our observation that sea fans involve more superficial retinal structures when compared with diabetic retinal neovascularization may be explained by the unique progression of sickle cell retinopathy. The initial retinal occlusions in PSR occur at the level of the inner retinal capillaries and precapillary arterioles, which lead to the formation of arteriolar–venular anastomoses.3 Sea fans often arise from the large-diameter venous feeders of these occluded arteriolar–venular anastomoses.2 This is in contrast to small-diameter capillary lumens that give rise to diabetic neovascularization. McLeod et al1 proposed that occlusion of these large-diameter venules in the high-flow system of an arteriolar– venular anastomosis may cause elevated upstream pressure, thereby increasing back pressure and slowly raising the oncotic pressure of the surrounding inner retinal tissue. They hypothesized that this can lead to the extrusion of the entire vessel distal to the
Fig. 2. SD-OCT of a diabetic neovascular membrane, illustrating the involvement of the retinal nerve fiber, ganglion cell, inner plexiform, inner nuclear, and outer plexiform layers (arrow).
101
MORPHOLOGY OF NEOVASCULARIZATION
occlusion site, so that the neovascular complex spares the deeper retinal structures. However, the occlusion of capillary beds in PDR may not raise the oncotic pressure of retinal tissue enough to cause the neovascular membrane to extrude to the retinal surface. The involvement of deeper retinal layers and presence of greater vitreoretinal traction in PDR may then create tighter retinal adherence and also help explain the greater risk of tractional retinal detachments in patients with diabetes compared with patients with sickle cell anemia.4,5 Key words: neovascularization, diabetes, sickle cell, sea fan, optical coherence tomography.
References 1. McLeod DS, Goldberg MF, Lutty GA. Dual-perspective analysis of vascular formations in sickle cell retinopathy. Arch Ophthalmol 1993;111:1234–1245. 2. Romayanada N, Goldberg MF, Green WR. Histopathology of sickle cell retinopathy. Trans Am Acad Ophthalmol Otolaryngol 1973;77:642–676. 3. Goldberg MF. Retinal neovascularization in sickle cell retinopathy. Trans Sect Ophthalmol Am Acad Ophthalmol Otolaryngol 1977;83:409–431. 4. Wolbarsht MI, Landers MB, Stefansson E. Vasodilation and the etiology of diabetic retinopathy: a new model. Ophthalmic Surg 1981;12:104–107. 5. Moriarty BJ, Acheson RW, Condon PI, Serjeant GR. Patterns of visual loss in untreated sickle cell retinopathy. Eye 1988;2:330–335.
Purpose: To analyze the in vivo morphology of the sea fan in proliferative sickle cell retinopathy and compare it with the neovascularization in proliferative diabetic retinopathy. Methods: Brief case report of spectral-domain optical coherence tomography imaging of a sea fan in a patient with sickle cell anemia and newly diagnosed proliferative sickle cell retinopathy, and morphologic comparison with spectral-domain optical coherence tomography imaging of a neovascular membrane in a diabetic patient with proliferative diabetic retinopathy. Results: Spectral-domain optical coherence tomography imaging revealed that the sea fan is a thicker caliber preretinal fibrovascular membrane involving primarily the retinal nerve fiber and ganglion cell layers. The diabetic membrane has more vitreous adhesions, and it is more closely intertwined with the retina, involving all the retinal layers down to the outer plexiform layer. Conclusion: Spectral-domain optical coherence tomography imaging identified important in vivo morphologic differences between neovascularization in proliferative sickle cell retinopathy and proliferative diabetic retinopathy. These differences were consistent with previous histological studies and may explain the increased risk of tractional retinal detachment in patients with diabetes. RETINAL CASES & BRIEF REPORTS 6:99–101, 2012
tomography. Here, we report the use of spectraldomain optical coherence tomography (SD-OCT) to analyze the in vivo morphology of the sea fan in PSR and compare it with diabetic neovascularization.
From the Department of Ophthalmology, New York University Langone Medical Center, New York, New York.
T
he classic sea fan of proliferative sickle cell retinopathy (PSR) has been previously studied by fluorescein angiography and histological methods.1,2 Sea fans are neovascular fronds composed of largediameter vessels, arising at the edge of perfused and ischemic retina.3 By contrast, retinal neovascularization in proliferative diabetic retinopathy (PDR) begins as loops or nets of fine vessels lying on the surface of the optic disk or along the arcades in the posterior retina.4 To our knowledge, there are no reports of direct imaging of sea fans by optical coherence
Case Reports Case 1 A 54-year-old man with sickle cell anemia and glaucoma presented for routine examination. Visual acuity was 20/20 in both eyes. Posterior examination revealed stage III sickle cell retinopathy with a sea fan neovascular frond in the temporal periphery of the right eye. Stage II sickle cell retinopathy was present in the left eye. SD-OCT of the sea fan demonstrated a large preretinal fibrovascular membrane arranged in thick cord like vascular channels associated with minimal vitreous traction (Figure 1). The neovascular membrane involved the retinal nerve fiber and ganglion cell layers, while leaving the inner plexiform and inner nuclear layers undisturbed. The right eye was treated with scatter argon laser photocoagulation to the areas of ischemic retina surrounding the sea fan, producing adequate involution and regression of the neovascular vessels.
Neither author has any financial/conflicting interests to disclose. Reprint requests: Francisco A. Folgar, MD, Department of Ophthalmology, New York University Langone Medical Center, 462 First Avenue, 5N-18, New York, NY 10016; e-mail: [email protected]
99
100
RETINAL CASES & BRIEF REPORTS´ 2012 VOLUME 6 NUMBER 1
Fig. 1. SD-OCT of a sea fan neovascular membrane in sickle cell anemia, illustrating the involvement of the retinal nerve fiber and ganglion cell layers, while leaving the inner plexiform and inner nuclear layers undisturbed (arrow).
Case 2 A 46-year-old man with type 2 diabetes mellitus for more than 10 years presented for his first diabetic eye examination. Visual acuity was 20/60 in the right eye and 20/50 in the left eye. Posterior examination revealed PDR in both eyes. SD-OCT of a large neovascular membrane nasal to the right optic nerve revealed a thin delicate fibrovascular membrane that was closely intertwined with the inner retina (Figure 2). The retinal nerve fiber, ganglion cell, inner plexiform, inner nuclear, and outer plexiform layers were all disrupted by the neovascular complex. SD-OCT also demonstrated prominent vitreous adhesions exerting traction on the neovascular membrane/retina complex. Panretinal laser photocoagulation was administered to both eyes over the course of multiple sessions. Direct photocoagulation of neovascular membranes was avoided, and laser spots were faint and spaced further apart in areas of retinal tissue directly surrounding the neovascularization, to avoid complications of vitreous hemorrhage or fibrovascular traction. The neovascularization regressed in both eyes in response to panretinal photocoagulation, and visual acuity remained stable.
Discussion SD-OCT in our two cases identified a number of morphologic differences between neovascularization in PSR and PDR. The relative absence of vitreous
traction in PSR when compared with the diabetic neovascular membrane is consistent with previous histological studies and may explain the increased risk of tractional retinal detachment in patients with diabetes.1,2,5 Furthermore, our observation that sea fans involve more superficial retinal structures when compared with diabetic retinal neovascularization may be explained by the unique progression of sickle cell retinopathy. The initial retinal occlusions in PSR occur at the level of the inner retinal capillaries and precapillary arterioles, which lead to the formation of arteriolar–venular anastomoses.3 Sea fans often arise from the large-diameter venous feeders of these occluded arteriolar–venular anastomoses.2 This is in contrast to small-diameter capillary lumens that give rise to diabetic neovascularization. McLeod et al1 proposed that occlusion of these large-diameter venules in the high-flow system of an arteriolar– venular anastomosis may cause elevated upstream pressure, thereby increasing back pressure and slowly raising the oncotic pressure of the surrounding inner retinal tissue. They hypothesized that this can lead to the extrusion of the entire vessel distal to the
Fig. 2. SD-OCT of a diabetic neovascular membrane, illustrating the involvement of the retinal nerve fiber, ganglion cell, inner plexiform, inner nuclear, and outer plexiform layers (arrow).
101
MORPHOLOGY OF NEOVASCULARIZATION
occlusion site, so that the neovascular complex spares the deeper retinal structures. However, the occlusion of capillary beds in PDR may not raise the oncotic pressure of retinal tissue enough to cause the neovascular membrane to extrude to the retinal surface. The involvement of deeper retinal layers and presence of greater vitreoretinal traction in PDR may then create tighter retinal adherence and also help explain the greater risk of tractional retinal detachments in patients with diabetes compared with patients with sickle cell anemia.4,5 Key words: neovascularization, diabetes, sickle cell, sea fan, optical coherence tomography.
References 1. McLeod DS, Goldberg MF, Lutty GA. Dual-perspective analysis of vascular formations in sickle cell retinopathy. Arch Ophthalmol 1993;111:1234–1245. 2. Romayanada N, Goldberg MF, Green WR. Histopathology of sickle cell retinopathy. Trans Am Acad Ophthalmol Otolaryngol 1973;77:642–676. 3. Goldberg MF. Retinal neovascularization in sickle cell retinopathy. Trans Sect Ophthalmol Am Acad Ophthalmol Otolaryngol 1977;83:409–431. 4. Wolbarsht MI, Landers MB, Stefansson E. Vasodilation and the etiology of diabetic retinopathy: a new model. Ophthalmic Surg 1981;12:104–107. 5. Moriarty BJ, Acheson RW, Condon PI, Serjeant GR. Patterns of visual loss in untreated sickle cell retinopathy. Eye 1988;2:330–335.
