RETINAL ARTERIOLAR MACROANEURYSMS OVERLYING THE OPTIC NERVE Bilal A. Khan, MD, Uday R. Desai, MD, Khuram A. Khan, MD, Fadi Calotti, MD
Background: Retinal arteriolar macroaneurysms typically involve the second and third order arterioles. Macroaneurysms involving the first order arterioles, specifically overlying the optic nerve, have been infrequently reported. Methods: This is a retrospective case series. Results: Two patients were found to have an arteriolar macroaneurysm overlying the optic nerve. The first, a 77-year-old man, had focal laser photocoagulation to the macroaneurysm. The second, a 75-year-old woman, had spontaneous resolution of the lesion without treatment. Final visual acuity was 20/25 in the treated patient compared to 20/80 in the untreated patient. Conclusion: Retinal arteriolar macroaneurysms overlying the optic nerve will involute spontaneously or as a result of focal laser photocoagulation. The associated macular edema may result in permanent visual loss. Focal laser treatment over the optic nerve did not cause optic nerve damage. RETINAL CASES & BRIEF REPORTS 3:253–258, 2009
rotic cardiovascular disease, as noted by Robertson,8 who first coined the term retinal macroaneurysm. There are only a few reported cases3– 6 of macroaneurysms involving the first order arteriole and specifically the optic nerve. Here, we present two cases of retinal arteriolar macroaneurysms overlying the optic nerve.
From Henry Ford Health System, Department of Ophthalmology, Detroit, Michigan.
A
cquired retinal macroaneurysms are fusiform or round dilations of the retinal arterioles that occur in the posterior fundus within the first three orders of arteriolar bifurcation.1 Retinal macroaneurysms most commonly involve second and third order arterioles.2 These lesions most frequently occur at the site of an arteriolar bifurcation or an arteriovenous crossing. The supratemporal artery is the most commonly reported site of involvement because patients with such involvement are more likely to have visual impairment. However, retinal macroaneurysms occasionally develop on the optic nerve head3– 6 or on a cilioretinal artery.7 Macroaneurysms usually affect patients in the sixth and seventh decades of life. Women make up the majority of reported cases. Most cases are unilateral, while 10% may be bilateral. Often associated are vascular problems such as hypertension and general arterioscle-
Case Reports Case 1 A 77-year-old man with a history of hypertension and coronary artery disease was referred to the retina service with a history of a sudden onset of metamorphopsia and central scotoma in his right eye. On initial examination he had a visual acuity of 20/30 in the right eye and 20/25 in the left eye. Intraocular pressure was 14 mmHg in the right eye and 15 mmHg in the left eye. The slit-lamp examination was significant for moderate nuclear sclerosis cataracts in both eyes. Funduscopic examination of the right eye revealed an arteriolar macroaneurysm on the supranasal aspect of the optic nerve. There were intraretinal hemorrhages superior to the optic nerve. Hard exudates with associated retinal edema were seen nasal to the nerve as well as in the macula (Figure 1). Arteriolar narrowing was seen in both eyes. Fluorescein angiogram revealed hyperfluorescence of the lesion in the mid and late phases with
The authors have no proprietary interests in this study. Reprint requests: Uday R. Desai, MD, Department of Ophthalmology, K-10, 2799 West Grand Blvd., Detroit, MI 48202; e-mail: [email protected]
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Fig. 1. The color photograph (top left) shows the arteriolar macroaneurysm over the surface of the optic nerve. There is evidence of hard exudates nasal to the optic nerve. The fovea is edematous and thus has a blunted reflex. There are scattered intraretinal hemorrhages superior to the optic nerve. The early angiographic photograph (top right) shows the macroaneurysm fluorescing along with the arterioles. The mid phase photograph (bottom left) shows increasing fluorescence of the aneurysm and it shows the capillary bed abnormalities superior to the optic nerve. The late photographs (bottom right) show leakage of the macroaneurysm and the superior capillary bed.
leakage superior to the optic nerve in the late phase (Figure 1). Optical coherence tomography confirmed intraretinal edema in the supranasal macula involving the fovea. Two months after presentation, the patient’s vision had decreased to 20/50 in the right eye and he had persistent hard exudates in the macula and superior to the optic nerve. The patient underwent focal laser photocoagulation to the macroaneurysm and grid photocoagulation to the retina superior to the optic nerve. The amount of energy used on the macroaneurysm was only enough to cause a very faint gray reaction. Also, a larger spot size was used to lessen the chance of rupturing the aneurysm. The treatment was focused on the aneurysm and as far anterior as possible to avoid thermal damage to the optic nerve. An argon laser was used for both the focal laser to the macroaneurysm as well as the grid laser photocoagulation superior to the optic nerve. The settings were as follows: spot size of 100 –200 m, duration of 0.1 second, and lesion intensity of 200 milliwatts with a total of 162 applications. Two months after the treatment the patient’s vision improved to 20/25 in the right eye. In addition, there was some resolution of the hard exudates nasal to the optic nerve as well as improvement in the foveal edema (Figure 2).
Case 2 A 75-year-old woman with a history of hypertension, diabetes, dyslipidemia, and nonproliferative diabetic retinopathy was referred to our retina service for a new onset of vitreous hemorrhage in her right eye. On examination her visual acuity was 20/20 in the right eye and 20/60 in the left eye. Intraocular pressure was 12 mmHg in the right eye and 10 mmHg in the left eye, and the slit-
lamp examination was significant for moderate nuclear sclerosis cataracts in both eyes. Fundus examination of the right eye revealed a pulsatile optic nerve lesion with associated vitreous hemorrhage (Figure 3). The left eye had intraretinal hemorrhages and retinal edema along the supratemporal vascular arcade consistent with a branch retinal vein occlusion. One week after presentation fluorescein angiography confirmed the macroaneurysm on the right optic nerve which demonstrated leakage in the late phase of the study (Figure 4). Magnetic resonance imaging and angiography were ordered because of the pulsatile nature of the lesion to rule out any tumor. These tests revealed a right orbital apex en plaque meningioma which did not appear to be involving the optic canal. The patient was seen by neuro-ophthalmology and neurosurgery who decided against surgical excision or decompression of the meningioma. They also believed that this meningioma was unrelated to the optic nerve macroaneurysm. During this period when the other evaluations were being performed, the patient was lost to ophthalmologic follow-up. On her subsequent return her vision had deteriorated to 20/350 in the right eye. That was 3 months after her initial presentation. At that time the optic nerve macroaneurysm was no longer pulsatile and had a grayish appearance. While there were also fine stellate exudates and edema in the macula, fluorescein angiography did not show leakage from the macroaneurysm (Figure 5). As a result, we believed there was no benefit at that point in performing focal laser photocoagulation. Sixteen months after presentation, there was some spontaneous resolution of the macular edema in the right eye and the vision improved to 20/80 without intervention (Figure 6).
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Fig. 2. Two months after laser photocoagulation, the color and red-free photographs (top left and right) show improvement in the hard exudates nasal to the optic nerve. The macula has less edema but the hard exudates have precipitated in the fovea. Fluorescein angiography (bottom left and right) shows less leakage from the macroaneurysm. Persistent leakage is seen from the superior capillary bed. Laser photocoagulation scars are seen superiorly.
Discussion The differential diagnosis of a mass lesion on the optic nerve includes nonvascular lesions such as papilledema, pseudopapilledema, and granulomas. Other conditions in the differential include vascular lesions such as neovascularization of the disk, arteriolar mac-
Fig. 3. The macroaneurysm is seen over the inferior pole of the optic nerve. Scattered intraretinal hemorrhages and vitreous hemorrhage are also evident.
roaneurysm, prepapillary loops, vein to vein collaterals, optociliary shunt vessels, retinal capillary hemangioma, and retinal cavernous hemangioma. Some of the above lesions have characteristic clinical appearances that would help differentiate them from arteriolar macroaneurysms. We can rule out nonvascular lesions in our patients because papilledema and pseudopapilledema are typically bilateral and are also associated with swelling of the optic nerve itself. This was not seen in our patients. Also, granulomas of the optic nerve have associated systemic findings which were absent in our patients. Our patients had vascular lesions which were anterior to the optic nerve and fluorescein angiography showed fusiform dilation contiguous with the arteriolar wall. The larger size of the lesion in Case 2 required differentiation from an endophytic capillary hemangioma. The early appearance of fluorescein within the dilation and associated late leakage was typical of an arteriolar macroaneurysm. If a hemangioma was present it would appear as a collection of multiple capillaries and not a dilation of a single vessel. Similarly, a capillary hemangioma would not be expected to involute as did our patient’s vascular lesion. The other vascular lesions in our differential were less likely after seeing the fluorescein results.
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Fig. 4. One week after presentation, the midphase angiography (left) shows the aneurysm filling with fluorescein. The hemorrhage is blocking fluorescence. The late phase angiogram (right) shows leakage from the macroaneurysm as well as leakage from the capillary bed nasally.
Case 2 displayed pulsations of the macroaneurysm. This is known to occur in some patients and in fact pulsations of the macroaneurysm may portend a greater risk of associated vitreous hemorrhage9 as was seen in our patient. Several series have reported on the natural history and treatment response of macroaneurysms.2,8,10,11 These reports show that spontaneous involution of the macroaneurysm is generally the rule. Since the natural history is very favorable, treatment of the macroaneurysm with laser photocoagulation is infrequently performed. In fact, some authors12 believe that laser
photocoagulation may result in worse visual outcome than observation alone. Their conclusions were probably influenced by the retrospective nature of their article, since the worst cases were probably the ones most likely to be treated. Treatment of the macroaneurysm is reserved for cases where associated edema and hemorrhage threatens the macula. In those cases laser photocoagulation is used to hasten the involution of the macroaneurysm. Laser photocoagulation can be performed using argon green (514 nm) or dye yellow (577 nm).13–15 The
Fig. 5. Three months after presentation, fundus photography shows marked improvement in the hemorrhage. The previously saccular aneurysm has flattened. Foveal edema is present. Angiography shows no filling or leakage of the previous macroaneurysm.
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Fig. 6. Sixteen months after presentation, the color and redfree photographs (top left and right) show the grayish remnant of the macroaneurysm at the inferior pole of the optic nerve. The foveal edema is resolved with a more distinct foveal reflex. Fluorescein angiography (bottom left and right) shows evidence of diabetic retinopathy but no evidence of the macroaneurysm.
yellow wavelength is well absorbed by hemoglobin, especially oxyhemoglobin. It has a high hemoglobin to melanin absorption ratio which minimizes damage to the pigment epithelium. This greater uptake by hemoglobin may theoretically focus greater energy within the macroaneurysm, and thereby facilitate involution. We were worried about the possibility that the longer yellow wavelength might result in deeper penetration of the laser energy into the optic nerve as compared to argon green. Since no definitive study shows superiority of either of these wavelengths, we chose to treat with argon green. Risks of laser photocoagulation include primarily hemorrhage from the aneurysm and development of a branch retinal artery occlusion (BRAO). Those risks are probably magnified when treating an aneurysm on the optic nerve. The higher flow volume of this proximal location may result in greater hemorrhage if the aneurysm were to rupture. The fact that higher volumes of blood are traversing this area is supported by the presence of arteriolar pulsations that were seen in our second patient. The development of a branch artery occlusion emanating from the optic nerve would be more serious since the affected area of the retina would be larger. Since the potential for hemorrhage and induction of a BRAO is great, we had to be very careful in the treatment of our first patient. We were careful to use low
energy to cause a very light gray burn as we wanted only a mild reaction to speed up the involutional process which would have otherwise occurred spontaneously at a slower rate. This lighter reaction along with the larger 100–200 m spot size may limit the possibility of hemorrhage and BRAO formation. The lighter reaction may also have an additional benefit in that it may be less likely to produce optic nerve damage in these patients with prepapillary macroaneurysms. The safety of laser on and around the optic nerve has been controversial. Garcia-Arumı´ et al have shown that photocoagulation of prepapillary retinal capillary hemangiomas is universally associated with central and arcuate scotomas.16 The difference between these patients and patients with the macroaneurysms is that the energy needed to close off a capillary hemangioma is much greater than that required to stimulate involution of a macroaneurysm. Experimental argon photocoagulation directly to the optic nerves of monkeys and humans support the notion that the lower treatment powers are less likely to result in damage.17 Specifically this study showed that parameters with powers less than 400 mW, 0.2 seconds, and 100 m spot size were less likely to cause neural parenchymal damage even when the nerve itself was treated. Light treatment on a prepapillary macroaneurysm may not induce significant optic nerve damage. Also, our treated patient’s vision slowly improved while our un-
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treated patient showed progressive visual loss. Therefore treatment should be considered for an arteriolar macroaneurysm on the optic nerve if associated blood or fluid threatens the macula.
10.
References
11.
1.
2.
3.
4. 5.
6. 7.
Chew EY, Murphy RP. Acquired retinal macroaneurysms. In: Ryan SJ, ed. Retina. Vol 2; Medical Retina. St Louis: Mosby, 2005;1499–1502. Abdel-Khalek MN, Richardson J. Retinal macroaneurysms: natural history and guidelines for treatment. Br J Ophthalmology 1986;70:2–11. Brown GC, Weinstock F. Arterial macroaneurysm on the optic disk presenting as a mass lesion. Ann Ophthalmol 1985;17:519–520. Kowal L, Steiner H. Arterial macroaneurysm of the optic disc. Aust NZ J Ophthalmol 1991;19:75–77. Ichibe M, Oya Y, Yoshizawa T, et al. Macroaneurysm on the optic disk associated with congenital retinal arterial malformation. Retina 2004;24:985–986. Quhill F, Smith J, Scotcher S. Arterial macroaneurysm on the optic disc. Eye 2004;18:321–322. Giuffre G, Montalto FP, Amodei G. Development of an isolated retinal macroaneurysm of the cilioretinal artery. Br J Ophthalmol 1987;71:445–448.
8. 9.
12.
13.
14.
15.
16.
17.
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Robertson DM. Macroaneurysms of the retinal arteries. Trans Am Acad Ophthalmol Otolaryngol 1973;77:55–67. Shults WT, Swan KC. Pulsatile aneurysms of the retinal arterial tree. Am J Ophthalmol 1974;77:304–309. Asdourian GK, Goldberg MJ, Jampol L, et al. Retinal macroaneurysms. Arch Ophthalmol 1977;95:624–628. Panton RW, Goldberg MF, Farber MD. Retinal arterial macroaneurysms: risk factors and natural history. Br J Ophthalmol 1990;74:595–600. Brown DM, Sobol WM, Folk JC, Weingeist TA. Retinal arteriolar macroaneurysm: long term visual outcome. Br J Ophthalmol 1994;78:534–538. Russell SR, Folk JC. Branch retinal artery occlusion after dye yellow photocoagulation of an arterial macroaneurysm. Am J Ophthalmol 1987;104:186–187. Mainster MA, Whitacre MM. Dye yellow photocoagulation of retinal arterial macroaneurysms. Am J Ophthalmol 1988; 105:97–98. Joondeph BC, Joondeph HC, Blair NP. Retinal macroaneurysms treated with the yellow dye laser. Retina 1989;9:187– 192. Garcia-Arumı´ J, Sararols LH, Cavero L, et al. Therapeutic options for capillary papillary hemangiomas. Ophthalmology 2000;107:48–54. Apple DJ, Wyhinny GJ, Goldberg MF, Polley EH. Experimental argon laser photocoagulation. II. Effects on the optic disc. Arch Ophthalmol 1976;94:296–304.
Background: Retinal arteriolar macroaneurysms typically involve the second and third order arterioles. Macroaneurysms involving the first order arterioles, specifically overlying the optic nerve, have been infrequently reported. Methods: This is a retrospective case series. Results: Two patients were found to have an arteriolar macroaneurysm overlying the optic nerve. The first, a 77-year-old man, had focal laser photocoagulation to the macroaneurysm. The second, a 75-year-old woman, had spontaneous resolution of the lesion without treatment. Final visual acuity was 20/25 in the treated patient compared to 20/80 in the untreated patient. Conclusion: Retinal arteriolar macroaneurysms overlying the optic nerve will involute spontaneously or as a result of focal laser photocoagulation. The associated macular edema may result in permanent visual loss. Focal laser treatment over the optic nerve did not cause optic nerve damage. RETINAL CASES & BRIEF REPORTS 3:253–258, 2009
rotic cardiovascular disease, as noted by Robertson,8 who first coined the term retinal macroaneurysm. There are only a few reported cases3– 6 of macroaneurysms involving the first order arteriole and specifically the optic nerve. Here, we present two cases of retinal arteriolar macroaneurysms overlying the optic nerve.
From Henry Ford Health System, Department of Ophthalmology, Detroit, Michigan.
A
cquired retinal macroaneurysms are fusiform or round dilations of the retinal arterioles that occur in the posterior fundus within the first three orders of arteriolar bifurcation.1 Retinal macroaneurysms most commonly involve second and third order arterioles.2 These lesions most frequently occur at the site of an arteriolar bifurcation or an arteriovenous crossing. The supratemporal artery is the most commonly reported site of involvement because patients with such involvement are more likely to have visual impairment. However, retinal macroaneurysms occasionally develop on the optic nerve head3– 6 or on a cilioretinal artery.7 Macroaneurysms usually affect patients in the sixth and seventh decades of life. Women make up the majority of reported cases. Most cases are unilateral, while 10% may be bilateral. Often associated are vascular problems such as hypertension and general arterioscle-
Case Reports Case 1 A 77-year-old man with a history of hypertension and coronary artery disease was referred to the retina service with a history of a sudden onset of metamorphopsia and central scotoma in his right eye. On initial examination he had a visual acuity of 20/30 in the right eye and 20/25 in the left eye. Intraocular pressure was 14 mmHg in the right eye and 15 mmHg in the left eye. The slit-lamp examination was significant for moderate nuclear sclerosis cataracts in both eyes. Funduscopic examination of the right eye revealed an arteriolar macroaneurysm on the supranasal aspect of the optic nerve. There were intraretinal hemorrhages superior to the optic nerve. Hard exudates with associated retinal edema were seen nasal to the nerve as well as in the macula (Figure 1). Arteriolar narrowing was seen in both eyes. Fluorescein angiogram revealed hyperfluorescence of the lesion in the mid and late phases with
The authors have no proprietary interests in this study. Reprint requests: Uday R. Desai, MD, Department of Ophthalmology, K-10, 2799 West Grand Blvd., Detroit, MI 48202; e-mail: [email protected]
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Fig. 1. The color photograph (top left) shows the arteriolar macroaneurysm over the surface of the optic nerve. There is evidence of hard exudates nasal to the optic nerve. The fovea is edematous and thus has a blunted reflex. There are scattered intraretinal hemorrhages superior to the optic nerve. The early angiographic photograph (top right) shows the macroaneurysm fluorescing along with the arterioles. The mid phase photograph (bottom left) shows increasing fluorescence of the aneurysm and it shows the capillary bed abnormalities superior to the optic nerve. The late photographs (bottom right) show leakage of the macroaneurysm and the superior capillary bed.
leakage superior to the optic nerve in the late phase (Figure 1). Optical coherence tomography confirmed intraretinal edema in the supranasal macula involving the fovea. Two months after presentation, the patient’s vision had decreased to 20/50 in the right eye and he had persistent hard exudates in the macula and superior to the optic nerve. The patient underwent focal laser photocoagulation to the macroaneurysm and grid photocoagulation to the retina superior to the optic nerve. The amount of energy used on the macroaneurysm was only enough to cause a very faint gray reaction. Also, a larger spot size was used to lessen the chance of rupturing the aneurysm. The treatment was focused on the aneurysm and as far anterior as possible to avoid thermal damage to the optic nerve. An argon laser was used for both the focal laser to the macroaneurysm as well as the grid laser photocoagulation superior to the optic nerve. The settings were as follows: spot size of 100 –200 m, duration of 0.1 second, and lesion intensity of 200 milliwatts with a total of 162 applications. Two months after the treatment the patient’s vision improved to 20/25 in the right eye. In addition, there was some resolution of the hard exudates nasal to the optic nerve as well as improvement in the foveal edema (Figure 2).
Case 2 A 75-year-old woman with a history of hypertension, diabetes, dyslipidemia, and nonproliferative diabetic retinopathy was referred to our retina service for a new onset of vitreous hemorrhage in her right eye. On examination her visual acuity was 20/20 in the right eye and 20/60 in the left eye. Intraocular pressure was 12 mmHg in the right eye and 10 mmHg in the left eye, and the slit-
lamp examination was significant for moderate nuclear sclerosis cataracts in both eyes. Fundus examination of the right eye revealed a pulsatile optic nerve lesion with associated vitreous hemorrhage (Figure 3). The left eye had intraretinal hemorrhages and retinal edema along the supratemporal vascular arcade consistent with a branch retinal vein occlusion. One week after presentation fluorescein angiography confirmed the macroaneurysm on the right optic nerve which demonstrated leakage in the late phase of the study (Figure 4). Magnetic resonance imaging and angiography were ordered because of the pulsatile nature of the lesion to rule out any tumor. These tests revealed a right orbital apex en plaque meningioma which did not appear to be involving the optic canal. The patient was seen by neuro-ophthalmology and neurosurgery who decided against surgical excision or decompression of the meningioma. They also believed that this meningioma was unrelated to the optic nerve macroaneurysm. During this period when the other evaluations were being performed, the patient was lost to ophthalmologic follow-up. On her subsequent return her vision had deteriorated to 20/350 in the right eye. That was 3 months after her initial presentation. At that time the optic nerve macroaneurysm was no longer pulsatile and had a grayish appearance. While there were also fine stellate exudates and edema in the macula, fluorescein angiography did not show leakage from the macroaneurysm (Figure 5). As a result, we believed there was no benefit at that point in performing focal laser photocoagulation. Sixteen months after presentation, there was some spontaneous resolution of the macular edema in the right eye and the vision improved to 20/80 without intervention (Figure 6).
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Fig. 2. Two months after laser photocoagulation, the color and red-free photographs (top left and right) show improvement in the hard exudates nasal to the optic nerve. The macula has less edema but the hard exudates have precipitated in the fovea. Fluorescein angiography (bottom left and right) shows less leakage from the macroaneurysm. Persistent leakage is seen from the superior capillary bed. Laser photocoagulation scars are seen superiorly.
Discussion The differential diagnosis of a mass lesion on the optic nerve includes nonvascular lesions such as papilledema, pseudopapilledema, and granulomas. Other conditions in the differential include vascular lesions such as neovascularization of the disk, arteriolar mac-
Fig. 3. The macroaneurysm is seen over the inferior pole of the optic nerve. Scattered intraretinal hemorrhages and vitreous hemorrhage are also evident.
roaneurysm, prepapillary loops, vein to vein collaterals, optociliary shunt vessels, retinal capillary hemangioma, and retinal cavernous hemangioma. Some of the above lesions have characteristic clinical appearances that would help differentiate them from arteriolar macroaneurysms. We can rule out nonvascular lesions in our patients because papilledema and pseudopapilledema are typically bilateral and are also associated with swelling of the optic nerve itself. This was not seen in our patients. Also, granulomas of the optic nerve have associated systemic findings which were absent in our patients. Our patients had vascular lesions which were anterior to the optic nerve and fluorescein angiography showed fusiform dilation contiguous with the arteriolar wall. The larger size of the lesion in Case 2 required differentiation from an endophytic capillary hemangioma. The early appearance of fluorescein within the dilation and associated late leakage was typical of an arteriolar macroaneurysm. If a hemangioma was present it would appear as a collection of multiple capillaries and not a dilation of a single vessel. Similarly, a capillary hemangioma would not be expected to involute as did our patient’s vascular lesion. The other vascular lesions in our differential were less likely after seeing the fluorescein results.
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Fig. 4. One week after presentation, the midphase angiography (left) shows the aneurysm filling with fluorescein. The hemorrhage is blocking fluorescence. The late phase angiogram (right) shows leakage from the macroaneurysm as well as leakage from the capillary bed nasally.
Case 2 displayed pulsations of the macroaneurysm. This is known to occur in some patients and in fact pulsations of the macroaneurysm may portend a greater risk of associated vitreous hemorrhage9 as was seen in our patient. Several series have reported on the natural history and treatment response of macroaneurysms.2,8,10,11 These reports show that spontaneous involution of the macroaneurysm is generally the rule. Since the natural history is very favorable, treatment of the macroaneurysm with laser photocoagulation is infrequently performed. In fact, some authors12 believe that laser
photocoagulation may result in worse visual outcome than observation alone. Their conclusions were probably influenced by the retrospective nature of their article, since the worst cases were probably the ones most likely to be treated. Treatment of the macroaneurysm is reserved for cases where associated edema and hemorrhage threatens the macula. In those cases laser photocoagulation is used to hasten the involution of the macroaneurysm. Laser photocoagulation can be performed using argon green (514 nm) or dye yellow (577 nm).13–15 The
Fig. 5. Three months after presentation, fundus photography shows marked improvement in the hemorrhage. The previously saccular aneurysm has flattened. Foveal edema is present. Angiography shows no filling or leakage of the previous macroaneurysm.
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Fig. 6. Sixteen months after presentation, the color and redfree photographs (top left and right) show the grayish remnant of the macroaneurysm at the inferior pole of the optic nerve. The foveal edema is resolved with a more distinct foveal reflex. Fluorescein angiography (bottom left and right) shows evidence of diabetic retinopathy but no evidence of the macroaneurysm.
yellow wavelength is well absorbed by hemoglobin, especially oxyhemoglobin. It has a high hemoglobin to melanin absorption ratio which minimizes damage to the pigment epithelium. This greater uptake by hemoglobin may theoretically focus greater energy within the macroaneurysm, and thereby facilitate involution. We were worried about the possibility that the longer yellow wavelength might result in deeper penetration of the laser energy into the optic nerve as compared to argon green. Since no definitive study shows superiority of either of these wavelengths, we chose to treat with argon green. Risks of laser photocoagulation include primarily hemorrhage from the aneurysm and development of a branch retinal artery occlusion (BRAO). Those risks are probably magnified when treating an aneurysm on the optic nerve. The higher flow volume of this proximal location may result in greater hemorrhage if the aneurysm were to rupture. The fact that higher volumes of blood are traversing this area is supported by the presence of arteriolar pulsations that were seen in our second patient. The development of a branch artery occlusion emanating from the optic nerve would be more serious since the affected area of the retina would be larger. Since the potential for hemorrhage and induction of a BRAO is great, we had to be very careful in the treatment of our first patient. We were careful to use low
energy to cause a very light gray burn as we wanted only a mild reaction to speed up the involutional process which would have otherwise occurred spontaneously at a slower rate. This lighter reaction along with the larger 100–200 m spot size may limit the possibility of hemorrhage and BRAO formation. The lighter reaction may also have an additional benefit in that it may be less likely to produce optic nerve damage in these patients with prepapillary macroaneurysms. The safety of laser on and around the optic nerve has been controversial. Garcia-Arumı´ et al have shown that photocoagulation of prepapillary retinal capillary hemangiomas is universally associated with central and arcuate scotomas.16 The difference between these patients and patients with the macroaneurysms is that the energy needed to close off a capillary hemangioma is much greater than that required to stimulate involution of a macroaneurysm. Experimental argon photocoagulation directly to the optic nerves of monkeys and humans support the notion that the lower treatment powers are less likely to result in damage.17 Specifically this study showed that parameters with powers less than 400 mW, 0.2 seconds, and 100 m spot size were less likely to cause neural parenchymal damage even when the nerve itself was treated. Light treatment on a prepapillary macroaneurysm may not induce significant optic nerve damage. Also, our treated patient’s vision slowly improved while our un-
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treated patient showed progressive visual loss. Therefore treatment should be considered for an arteriolar macroaneurysm on the optic nerve if associated blood or fluid threatens the macula.
10.
References
11.
1.
2.
3.
4. 5.
6. 7.
Chew EY, Murphy RP. Acquired retinal macroaneurysms. In: Ryan SJ, ed. Retina. Vol 2; Medical Retina. St Louis: Mosby, 2005;1499–1502. Abdel-Khalek MN, Richardson J. Retinal macroaneurysms: natural history and guidelines for treatment. Br J Ophthalmology 1986;70:2–11. Brown GC, Weinstock F. Arterial macroaneurysm on the optic disk presenting as a mass lesion. Ann Ophthalmol 1985;17:519–520. Kowal L, Steiner H. Arterial macroaneurysm of the optic disc. Aust NZ J Ophthalmol 1991;19:75–77. Ichibe M, Oya Y, Yoshizawa T, et al. Macroaneurysm on the optic disk associated with congenital retinal arterial malformation. Retina 2004;24:985–986. Quhill F, Smith J, Scotcher S. Arterial macroaneurysm on the optic disc. Eye 2004;18:321–322. Giuffre G, Montalto FP, Amodei G. Development of an isolated retinal macroaneurysm of the cilioretinal artery. Br J Ophthalmol 1987;71:445–448.
8. 9.
12.
13.
14.
15.
16.
17.
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