OPTICAL COHERENCE TOMOGRAPHIC FINDINGS IN BIETTI’S CRYSTALLINE TAPETORETINAL DYSTROPHY Giuseppe Giuffre`, PHD, Mauro G. Distefano, MD, Luigi Di Rosa, MD
Purpose: To report the optical coherence tomography (OCT) findings of Bietti crystalline tapetoretinal dystrophy. Design: Observational case report. Methods: A subject with Bietti crystalline tapetoretinal dystrophy was evaluated with ophthalmoscopy, fluorescein angiography, and OCT (Stratus). Results: OCT showed thinning and hyporeflectivity of the outer nuclear layer in the macula due to photoreceptor degeneration. The retinal areas showing atrophy of the retinal pigment epithelium displayed greater penetration of the optical beam into the choroid and visualization of residual choroidal vessels. The hyperreflective band normally seen under the neurosensory retina was extremely wide when atrophy of the entire retinal pigment epithelium/choriocapillaris complex was found. Above this band, and within the neurosensory retina, some hyperreflective dot-like lesions were seen that could be related to crystals. Conclusions: In cases of Bietti crystalline tapetoretinal dystrophy, OCT shows changes secondary to fundus atrophy and more specific changes that can be related to the presence of crystals, thereby making OCT particularly useful for demonstrating macular atrophic abnormalities. RETINAL CASES & BRIEF REPORTS 1:236 –238, 2007
From the Section of Ophthalmology, Department of Neurology, Ophthalmology, and Psychiatry, University of Palermo, Italy.
useful test permitting the study of the macular and the midperipheral retina. Additionally, it can provide important information about certain conditions of the neurosensory retina and RPE that are often not fully appreciated, even with the two aforementioned diagnostic tests. In this report, we describe the OCT findings of a peculiar dystrophy of the fundus of the eye, Bietti’s crystalline tapetoretinal dystrophy.2
O
ptical coherence tomography (OCT) is a diagnostic tool used mainly to investigate diseases of the neurosensory retina. However, OCT is also useful in affections involving photoreceptors, retinal pigment epithelium (RPE), and choriocapillaris, such as retinitis pigmentosa. In these cases the OCT generally shows atrophy of the retina and particularly the outer nuclear layer.1 As regards tapetoretinal dystrophies, changes in RPE are well demonstrated by fluorescein angiography, while areas of choriocapillary atrophy are better visualized by indocyanine green angiography. In this group of diseases, the OCT represents a
Case Report A 43-year-old woman reported a slow, progressive, bilateral loss of vision over the previous 5 years. Her visual acuity was 20/50 in the right eye and 20/30 in the left eye. Ophthalmoscopy showed numerous glittering crystals, especially in the macula (Figure 1). There was wide retinal and choroidal atrophy in the posterior pole and midperiphery, and some choroidal vessels were easily seen in these profoundly atrophic zones. The cornea was normal without presence of crystals. The fluorescein angiography in the macula showed some hypofluorescent spots as concomitant retinal pigment epithelium and choriocapillaris atrophy. In the peripheral part of the posterior pole and midperiphery, a background hypofluorescence could be seen, against which some major choroidal vessels
The authors do not have proprietary interest in products cited in this article. Reprint requests: Giuseppe Giuffre`, PhD, University Eye Clinic, Via L. Giuffre` 13, 90127 Palermo, Italy; e-mail: giuseppe.giuffre@ aliceposta.it
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OPTICAL COHERENCE TOMOGRAPHIC FINDINGS IN BIETTI’S CRYSTALLINE TAPETORETINAL DYSTROPHY 237
Fig. 1. Fundus photograph of the right eye of a woman with Bietti’s crystalline tapetoretinal dystrophy showing several glittering yellow crystals in the posterior pole. Some choroidal vessels are well visualized in midperiphery due to atrophy of the retinal pigment epithelium. The arrow shows the area of the optical coherence tomography scan seen in Figure 3A.
stood out (Figure 2). Wide annular scotoma was found in the visual fields. The scotopic and photopic electroretinograms were both subnormal. The Stratus OCT showed a thin, atrophic retina and the outer nuclear layer was reduced in both the fovea and macula (Figure 3A). The areas of atrophic RPE with persistence of choriocapillaris displayed a greater penetration of the optical beam with visualization of choroidal vessels (Figure 3B). The retinal areas in which the choriocapillaris was also lacking showed a widened hyperreflective band probably corresponding to the choroid (Figure 3C). The crystals were not clearly appreciated during OCT examination, although some hyperreflective pointlike lesions were seen within the neurosensory retina and on the hyperreflective band. The pa-
Fig. 2. Fluorescein angiography (venous phase) of the left eye of a patient with Bietti’s crystalline tapetoretinal dystrophy. A patch of transmission hyperfluorescence is seen in the macula revealing atrophy of retinal pigment epithelium and persistence of choriocapillaris. Residual choroidal vessels are seen in midperiphery as hyperfluorescent streaks on a dark background secondary to profound atrophy of the retinal pigment epithelium/choriocapillaris complex. The vertical arrow indicates the area of the optical coherence tomography scan in Figure 3B, and the horizontal arrow corresponds to the area of the optical coherence tomography scan in Figure 3C.
Fig. 3. Optical coherence tomography (Stratus OCT) in Bietti’s crystalline tapetoretinal dystrophy. A, Horizontal macular scan of the right eye, corresponding to the arrow in Figure 1, showing a hyporeflective outer nuclear layer significantly thinner than normal in both the fovea (arrow; foveal thickness ⫽ 115 m) and peripheral to the fovea as a sign of degeneration of photoreceptors. The retina/retinal pigment epithelium (RPE) atrophy allows a greater penetration of the optical beam with visualization of choroidal vessels. The hyperreflective dotlike lesion seen on the left, above the hyperreflective band, could be a crystal. B, Vertical scan of the superior part of the posterior pole of the left eye corresponding to the vertical arrow in Figure 2. On the left, the foveal depression is seen (arrow; foveal thickness ⫽ 126 m). The macular neurosensory retina is thicker than in the right eye; there is enhanced reflectivity of the choroid due to increased penetration of the optical beam in this macular area of retinal and RPE atrophy. On the right (horizontal white line) in a zone in which the fluorescein angiography shows atrophy of the RPE and choriocapillaris, a thinned, atrophic retina is seen in association with a greater penetration of the beam towards the choroid. The dark hyporeflective round images seen below the highly reflective line correspond to choroidal vessels. C, Horizontal scan performed nasal to the left optic disk and corresponding to the horizontal arrow in Figure 2 in an area where the fluorescein angiography shows profound atrophy of retina, RPE, choriocapillaris, and choroid. The retinal lines are thinned and they are seen above a highly hyperreflective, irregularly thick band. Since the RPE and choriocapillaris are totally atrophic, this band only corresponds to the choroid. Some irregularities are visible on this hyperreflective band that could be interpreted as crystals.
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tient had normal levels of oxalates in the urine and ornithine in the serum. A diagnosis of Bietti’s crystalline tapetoretinal dystrophy without corneal involvement was made.
Discussion In various tapetoretinal dystrophies, the OCT can show the atrophy of neurosensory retina, seen as a thinning of retinal layers,1 as well as the possible presence of a macular edema. In the case of the Bietti’s crystalline tapetoretinal dystrophy we report here, the OCT showed thinning and reduced reflectivity of the outer nuclear layer in the fovea and the area peripheral to the foveal region, which is a sign of photoreceptor degeneration. Another observation we made was a wide and irregularly thick hyperreflective band in areas of loss of RPE that we interpreted as secondary to the penetration of the optical beam into the choroid. A greater grade of choroidal reflectivity could be seen if the choriocapillaris was also lacking. These OCT aspects mirror the fluorescein angiographic findings of transmission hyperfluorescence secondary to RPE atrophy and hypofluorescence due to atrophy of the whole RPE/choriocapillaris complex. Histopathologic reports of Bietti’s crystalline tapetoretinal dystrophy show severe retinal degeneration and loss and sclerosis of the choriocapillaris.3 The OCT characteristics that we observed are different from those reported by Meyer et al,4 the only other description that we found in literature. The Meyer et al study disclosed an abnormally high hyperreflectivity throughout the entire neuroretina and a thickened RPE/choriocapillaris complex, and ascribed this finding to light scattering by intraretinal deposits. We did not find such a hyperreflectivity of the neuroretina, and we attributed the abnormally thick hyperreflective band found below the neuroretina to backscattering from the choroid in the presence of atrophy of RPE/choriocapillaris rather than to a thickening of these layers. In addition, we found that the thicker and more hyperreflective band was seen in midperiphery (and not in the macula) where the atrophy was more marked and the crystals less numerous. Although we
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did not observe a certain OCT feature of the intraretinal crystals, some hyperreflective pointlike lesions seen within the neurosensory retina and some irregularities appreciated on the hyperreflective band could be related to crystals. The OCT performed in other diseases characterized by intraretinal crystals like cathaxanthine retinopathy5 and chronic retinal detachment6 show that crystals are seen as small hyperreflective lesions and not as a diffuse hyperreflectivity. Some of the inconsistent findings found in the Meyer et al4 report compared to ours could be explained by the different stage of the disease observed in the separate studies, since the greater number of crystals present in the early case described by Meyer et al4 could produce an extensive backscattering. Additional differences may be attributable to the earlier model of OCT (OCT 2000) used in the Meyer study, which has a reduced axial resolution. Bietti’s crystalline tapetoretinal dystrophy is an inherited, untreatable affection; hence, the OCT has no value as a therapeutic approach. However, it could be a useful noninvasive test to assess the degree of atrophy of the fundus, and particularly the changes of the macula. References 1.
2.
3.
4.
5.
6.
Hamada S, Yoshida K, Chihara E. Optical coherence tomography images of retinitis pigmentosa. Ophthalmic Surg Lasers 2000;31:253–256. Mataftsi A, Zografos L, Milla E, et al. Bietti’s crystalline corneoretinal dystrophy. A cross-sectional study. Retina 2004; 24:416–426. Kaiser-Kupfer MI, Chan CC, Markello TC, et al. Clinical, biochemical and pathologic correlations in Bietti’s crystalline dystrophy. Am J Ophthalmol 1994;118:569–582. Meyer CH, Rodrigues EB, Mennel S, Schmidt JC. Optical coherence tomography in a case of Bietti’s crystalline dystrophy. Acta Ophthalmol Scand 2005;82:609–612. Chan A, Ko TH, Duker JS. Ultrahigh-resolution optical coherence tomography of cathaxanthine retinal crystals. Ophthalmic Surg Lasers 2006;37:138–139. Habib MS, Byrne S, McCarthy JH, Steel DH. Refractile superficial retinal crystals and chronic retinal detachment. Case report. BMC Ophthalmol 2006;6:3.
Purpose: To report the optical coherence tomography (OCT) findings of Bietti crystalline tapetoretinal dystrophy. Design: Observational case report. Methods: A subject with Bietti crystalline tapetoretinal dystrophy was evaluated with ophthalmoscopy, fluorescein angiography, and OCT (Stratus). Results: OCT showed thinning and hyporeflectivity of the outer nuclear layer in the macula due to photoreceptor degeneration. The retinal areas showing atrophy of the retinal pigment epithelium displayed greater penetration of the optical beam into the choroid and visualization of residual choroidal vessels. The hyperreflective band normally seen under the neurosensory retina was extremely wide when atrophy of the entire retinal pigment epithelium/choriocapillaris complex was found. Above this band, and within the neurosensory retina, some hyperreflective dot-like lesions were seen that could be related to crystals. Conclusions: In cases of Bietti crystalline tapetoretinal dystrophy, OCT shows changes secondary to fundus atrophy and more specific changes that can be related to the presence of crystals, thereby making OCT particularly useful for demonstrating macular atrophic abnormalities. RETINAL CASES & BRIEF REPORTS 1:236 –238, 2007
From the Section of Ophthalmology, Department of Neurology, Ophthalmology, and Psychiatry, University of Palermo, Italy.
useful test permitting the study of the macular and the midperipheral retina. Additionally, it can provide important information about certain conditions of the neurosensory retina and RPE that are often not fully appreciated, even with the two aforementioned diagnostic tests. In this report, we describe the OCT findings of a peculiar dystrophy of the fundus of the eye, Bietti’s crystalline tapetoretinal dystrophy.2
O
ptical coherence tomography (OCT) is a diagnostic tool used mainly to investigate diseases of the neurosensory retina. However, OCT is also useful in affections involving photoreceptors, retinal pigment epithelium (RPE), and choriocapillaris, such as retinitis pigmentosa. In these cases the OCT generally shows atrophy of the retina and particularly the outer nuclear layer.1 As regards tapetoretinal dystrophies, changes in RPE are well demonstrated by fluorescein angiography, while areas of choriocapillary atrophy are better visualized by indocyanine green angiography. In this group of diseases, the OCT represents a
Case Report A 43-year-old woman reported a slow, progressive, bilateral loss of vision over the previous 5 years. Her visual acuity was 20/50 in the right eye and 20/30 in the left eye. Ophthalmoscopy showed numerous glittering crystals, especially in the macula (Figure 1). There was wide retinal and choroidal atrophy in the posterior pole and midperiphery, and some choroidal vessels were easily seen in these profoundly atrophic zones. The cornea was normal without presence of crystals. The fluorescein angiography in the macula showed some hypofluorescent spots as concomitant retinal pigment epithelium and choriocapillaris atrophy. In the peripheral part of the posterior pole and midperiphery, a background hypofluorescence could be seen, against which some major choroidal vessels
The authors do not have proprietary interest in products cited in this article. Reprint requests: Giuseppe Giuffre`, PhD, University Eye Clinic, Via L. Giuffre` 13, 90127 Palermo, Italy; e-mail: giuseppe.giuffre@ aliceposta.it
236
OPTICAL COHERENCE TOMOGRAPHIC FINDINGS IN BIETTI’S CRYSTALLINE TAPETORETINAL DYSTROPHY 237
Fig. 1. Fundus photograph of the right eye of a woman with Bietti’s crystalline tapetoretinal dystrophy showing several glittering yellow crystals in the posterior pole. Some choroidal vessels are well visualized in midperiphery due to atrophy of the retinal pigment epithelium. The arrow shows the area of the optical coherence tomography scan seen in Figure 3A.
stood out (Figure 2). Wide annular scotoma was found in the visual fields. The scotopic and photopic electroretinograms were both subnormal. The Stratus OCT showed a thin, atrophic retina and the outer nuclear layer was reduced in both the fovea and macula (Figure 3A). The areas of atrophic RPE with persistence of choriocapillaris displayed a greater penetration of the optical beam with visualization of choroidal vessels (Figure 3B). The retinal areas in which the choriocapillaris was also lacking showed a widened hyperreflective band probably corresponding to the choroid (Figure 3C). The crystals were not clearly appreciated during OCT examination, although some hyperreflective pointlike lesions were seen within the neurosensory retina and on the hyperreflective band. The pa-
Fig. 2. Fluorescein angiography (venous phase) of the left eye of a patient with Bietti’s crystalline tapetoretinal dystrophy. A patch of transmission hyperfluorescence is seen in the macula revealing atrophy of retinal pigment epithelium and persistence of choriocapillaris. Residual choroidal vessels are seen in midperiphery as hyperfluorescent streaks on a dark background secondary to profound atrophy of the retinal pigment epithelium/choriocapillaris complex. The vertical arrow indicates the area of the optical coherence tomography scan in Figure 3B, and the horizontal arrow corresponds to the area of the optical coherence tomography scan in Figure 3C.
Fig. 3. Optical coherence tomography (Stratus OCT) in Bietti’s crystalline tapetoretinal dystrophy. A, Horizontal macular scan of the right eye, corresponding to the arrow in Figure 1, showing a hyporeflective outer nuclear layer significantly thinner than normal in both the fovea (arrow; foveal thickness ⫽ 115 m) and peripheral to the fovea as a sign of degeneration of photoreceptors. The retina/retinal pigment epithelium (RPE) atrophy allows a greater penetration of the optical beam with visualization of choroidal vessels. The hyperreflective dotlike lesion seen on the left, above the hyperreflective band, could be a crystal. B, Vertical scan of the superior part of the posterior pole of the left eye corresponding to the vertical arrow in Figure 2. On the left, the foveal depression is seen (arrow; foveal thickness ⫽ 126 m). The macular neurosensory retina is thicker than in the right eye; there is enhanced reflectivity of the choroid due to increased penetration of the optical beam in this macular area of retinal and RPE atrophy. On the right (horizontal white line) in a zone in which the fluorescein angiography shows atrophy of the RPE and choriocapillaris, a thinned, atrophic retina is seen in association with a greater penetration of the beam towards the choroid. The dark hyporeflective round images seen below the highly reflective line correspond to choroidal vessels. C, Horizontal scan performed nasal to the left optic disk and corresponding to the horizontal arrow in Figure 2 in an area where the fluorescein angiography shows profound atrophy of retina, RPE, choriocapillaris, and choroid. The retinal lines are thinned and they are seen above a highly hyperreflective, irregularly thick band. Since the RPE and choriocapillaris are totally atrophic, this band only corresponds to the choroid. Some irregularities are visible on this hyperreflective band that could be interpreted as crystals.
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tient had normal levels of oxalates in the urine and ornithine in the serum. A diagnosis of Bietti’s crystalline tapetoretinal dystrophy without corneal involvement was made.
Discussion In various tapetoretinal dystrophies, the OCT can show the atrophy of neurosensory retina, seen as a thinning of retinal layers,1 as well as the possible presence of a macular edema. In the case of the Bietti’s crystalline tapetoretinal dystrophy we report here, the OCT showed thinning and reduced reflectivity of the outer nuclear layer in the fovea and the area peripheral to the foveal region, which is a sign of photoreceptor degeneration. Another observation we made was a wide and irregularly thick hyperreflective band in areas of loss of RPE that we interpreted as secondary to the penetration of the optical beam into the choroid. A greater grade of choroidal reflectivity could be seen if the choriocapillaris was also lacking. These OCT aspects mirror the fluorescein angiographic findings of transmission hyperfluorescence secondary to RPE atrophy and hypofluorescence due to atrophy of the whole RPE/choriocapillaris complex. Histopathologic reports of Bietti’s crystalline tapetoretinal dystrophy show severe retinal degeneration and loss and sclerosis of the choriocapillaris.3 The OCT characteristics that we observed are different from those reported by Meyer et al,4 the only other description that we found in literature. The Meyer et al study disclosed an abnormally high hyperreflectivity throughout the entire neuroretina and a thickened RPE/choriocapillaris complex, and ascribed this finding to light scattering by intraretinal deposits. We did not find such a hyperreflectivity of the neuroretina, and we attributed the abnormally thick hyperreflective band found below the neuroretina to backscattering from the choroid in the presence of atrophy of RPE/choriocapillaris rather than to a thickening of these layers. In addition, we found that the thicker and more hyperreflective band was seen in midperiphery (and not in the macula) where the atrophy was more marked and the crystals less numerous. Although we
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2007
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VOLUME 1
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NUMBER 4
did not observe a certain OCT feature of the intraretinal crystals, some hyperreflective pointlike lesions seen within the neurosensory retina and some irregularities appreciated on the hyperreflective band could be related to crystals. The OCT performed in other diseases characterized by intraretinal crystals like cathaxanthine retinopathy5 and chronic retinal detachment6 show that crystals are seen as small hyperreflective lesions and not as a diffuse hyperreflectivity. Some of the inconsistent findings found in the Meyer et al4 report compared to ours could be explained by the different stage of the disease observed in the separate studies, since the greater number of crystals present in the early case described by Meyer et al4 could produce an extensive backscattering. Additional differences may be attributable to the earlier model of OCT (OCT 2000) used in the Meyer study, which has a reduced axial resolution. Bietti’s crystalline tapetoretinal dystrophy is an inherited, untreatable affection; hence, the OCT has no value as a therapeutic approach. However, it could be a useful noninvasive test to assess the degree of atrophy of the fundus, and particularly the changes of the macula. References 1.
2.
3.
4.
5.
6.
Hamada S, Yoshida K, Chihara E. Optical coherence tomography images of retinitis pigmentosa. Ophthalmic Surg Lasers 2000;31:253–256. Mataftsi A, Zografos L, Milla E, et al. Bietti’s crystalline corneoretinal dystrophy. A cross-sectional study. Retina 2004; 24:416–426. Kaiser-Kupfer MI, Chan CC, Markello TC, et al. Clinical, biochemical and pathologic correlations in Bietti’s crystalline dystrophy. Am J Ophthalmol 1994;118:569–582. Meyer CH, Rodrigues EB, Mennel S, Schmidt JC. Optical coherence tomography in a case of Bietti’s crystalline dystrophy. Acta Ophthalmol Scand 2005;82:609–612. Chan A, Ko TH, Duker JS. Ultrahigh-resolution optical coherence tomography of cathaxanthine retinal crystals. Ophthalmic Surg Lasers 2006;37:138–139. Habib MS, Byrne S, McCarthy JH, Steel DH. Refractile superficial retinal crystals and chronic retinal detachment. Case report. BMC Ophthalmol 2006;6:3.
