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Foveal hypoplasia associated with Dandy-Walker syndrome
CASE REPORT Foveal hypoplasia associated with Dandy-Walker syndrome Dandy-Walker syndrome (DWS) is characterized by anterior-posterior enlargement of the posterior fossa, cerebellar vermis hypoplasia, fourth ventricle cystic dilation, as well as upward displacement of the transverse sinuses and torcula.1 Patients can have a wide range of clinical presentations, from being asymptomatic to requiring neurosurgical intervention.1 Foveal hypoplasia is characterized by continuity of the inner retinal layers in the fovea and may be found in isolation or be associated with albinism, achromatopsia, aniridia, or PAX6 mutation.2 Nanophthalmos, microphthalmos, posterior microphthalmos, and retinopathy of prematurity can result in a lack of foveal pit; however, there is a lack of continuity of the inner retinal layers in the fovea in these disorders. Here we describe what is, to our knowledge, the first case of foveal hypoplasia in a patient with DWS.
CASE REPORT A 12-year-old female with a history of DWS was referred to our clinic for nonprogressive chronically poor vision. She was born at full term and had no neurologic symptoms. Her eyes were orthotropic for distance and near with no history of childhood ptosis or strabismus. There was no history of refractive error. Her visual acuity was 4/10 OU. External and anterior segment examinations were unremarkable bilaterally without any abnormal skin pigmentation or iris abnormalities. Fundus examination revealed a lack of a foveal reflex with vessels crossing the central fovea and mild vessel tortuosity in both eyes. There was an abnormal continuity of the inner retinal layers into the fovea on optical coherence tomography (OCT) bilaterally. All the inner retinal layers (including the inner nuclear layer, inner plexiform layer and ganglion cell layer) were discernible in the foveal center of both eyes (Fig. 1).
Full field and flicker electroretinogram were within normal limits. Brain magnetic resonance imaging demonstrated an enlarged posterior fossa with upward displacement of tentorium cerebelli, fourth ventricular enlargement, vermian hypoplasia and hypoplasia of corpus callosum compatible with DWS.
DISCUSSION DWS is a well-characterized congenital malformation. Associated vitreoretinal abnormalities have increasingly been described and include bilateral macular edema,3 non-rhegmatogenous retinal detachment,4 peripheral retinal ischemia,5 and severe myopia5,6 with macular retinal pigment epithelial thinning, posterior staphyloma, and peripheral vitreous membranes in the retinal periphery.6 The case presented herein represents the first report of foveal hypoplasia in a patient with DWS. According to the OCT-based grading system proposed by Thomas et al., the present patient would be characterized as having a grade 2 foveal hypoplasia with visual acuity being compatible with this degree of hypoplasia.2 Optic neuropathy from hydrocephalus is a significant concern in patients with DWS. A better understanding of the causes of subnormal vision and the ophthalmic manifestations of DWS may prevent unnecessary ancillary tests in patients with abnormal vision and may help better categorize the pathogenesis of this disease. The late embryonic period is critical for the development of the retina and central nervous system (which both embryologically originate from neuro-ectoderm), with developmental arrest in this period being hypothesized to be the cause of DWS. DWS and some retinal degenerations (including some variants of retinitis pigmentosa) have been classified as ciliopathies, a relatively recent disease categorization.7–9 Most of the pathologic alternations that have been categorized take place at the cilium-centrosome complex, which is the universal system for managing external signals and cellular detection.7
Fig. 1 — Optical coherence tomogram of the macula of the right (A) and left (B) eye with corresponding scanning laser ophthalmoscopy photographs which demonstrate the preservation of the inner retinal layers in the foveal centers in addition to vessels that abnormally cross the foveal pit. There is no disruption in ellipsoid zone. CAN J OPHTHALMOL — VOL. ], NO. ], ] 2017
1
Case Report Interestingly, Tranos et al. observed bilateral macular edema in a patient with DWS,3 which is not unlike what is seen in patients with retinitis pigmentosa. The possible role of cilia in the pathogenesis of foveal hypoplasia may represent a novel and yet unexplored mechanism of disease that could be the basis for future study.
The authors have no proprietary or commercial interest in any materials discussed in this article.
Disclosure:
Nazanin Ebrahimiadib, MD,* Siamak Karkheiran, MD,† Ramak Roohipoor, MD,* Reza Karkhaneh, MD,* Bobeck S. Modjtahedi, MD‡ *Eye
Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran; †Department of Neurology, Rasool Akram Hospital, Iran University of Medical Sciences, Tehran, Iran; ‡Department of Ophthalmology, Southern California Permanente Medical Group, Baldwin Park, Calif. Correspondence to: Bobeck S. Modjtahedi: [email protected]
2
CAN J OPHTHALMOL — VOL. ], NO. ], ] 2017
REFERENCES 1. Jha VC, Kumar R, Srivastav AK, Mehrotra A, Sahu RN. A case series of 12 patients with incidental asymptomatic Dandy-Walker syndrome and management. Childs Nerv Syst. 2012;28:861-7. 2. Thomas MG, Kumar A, Mohammad S, et al. Structural grading of foveal hypoplasia using spectral-domain optical coherence tomography a predictor of visual acuity? Ophthalmology. 2011;118:1653-60. 3. Tranos P, Dervenis N, Kiouras S. Bilateral macular edema: a new ocular feature of Dandy-Walker syndrome [Epub ahead of print]. Semin Ophthalmol. 2016. 4. Sakurai E, Shirai S, Ozeki H, Majima A. [A case of nonrhegmatogenous retinal detachment in Dandy-Walker Syndrome]. Nippon Ganka Gakkai Zasshi. 1996;100:832-6. 5. Rusu I, Gupta MP, Patel SN, Oltra E, Chan RV. Retinal vascular nonperfusion in siblings with Dandy-Walker variant. J AAPOS. 2016;20:174-7. 6. de Crecchio G, Cennamo G, de Leeuw N, et al. Severe myopia with unusual retinal anomalies and Dandy-Walker sequence in two sibs. A distinct new neuro-ocular disorder. Ophthalmic Genet. 2013;34:254-7. 7. Hildebrandt F, Benzing T, Katsanis N. Ciliopathies. N Engl J Med. 2011;364:1533-43. 8. Badano JL, Mitsuma N, Beales PL, Katsanis N. The ciliopathies: an emerging class of human genetic disorders. Annu Rev Genomics Hum Genet. 2006;7:125-48. 9. Baker K, Beales PL. Making sense of cilia in disease: the human ciliopathies. Am J Med Genet C Semin Med Genet. 2009;151C:281-95. Can J Ophthalmol 2017;]:]]]–]]] 0008-4182/17/$-see front matter & 2017 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jcjo.2017.01.020
CASE REPORT A 12-year-old female with a history of DWS was referred to our clinic for nonprogressive chronically poor vision. She was born at full term and had no neurologic symptoms. Her eyes were orthotropic for distance and near with no history of childhood ptosis or strabismus. There was no history of refractive error. Her visual acuity was 4/10 OU. External and anterior segment examinations were unremarkable bilaterally without any abnormal skin pigmentation or iris abnormalities. Fundus examination revealed a lack of a foveal reflex with vessels crossing the central fovea and mild vessel tortuosity in both eyes. There was an abnormal continuity of the inner retinal layers into the fovea on optical coherence tomography (OCT) bilaterally. All the inner retinal layers (including the inner nuclear layer, inner plexiform layer and ganglion cell layer) were discernible in the foveal center of both eyes (Fig. 1).
Full field and flicker electroretinogram were within normal limits. Brain magnetic resonance imaging demonstrated an enlarged posterior fossa with upward displacement of tentorium cerebelli, fourth ventricular enlargement, vermian hypoplasia and hypoplasia of corpus callosum compatible with DWS.
DISCUSSION DWS is a well-characterized congenital malformation. Associated vitreoretinal abnormalities have increasingly been described and include bilateral macular edema,3 non-rhegmatogenous retinal detachment,4 peripheral retinal ischemia,5 and severe myopia5,6 with macular retinal pigment epithelial thinning, posterior staphyloma, and peripheral vitreous membranes in the retinal periphery.6 The case presented herein represents the first report of foveal hypoplasia in a patient with DWS. According to the OCT-based grading system proposed by Thomas et al., the present patient would be characterized as having a grade 2 foveal hypoplasia with visual acuity being compatible with this degree of hypoplasia.2 Optic neuropathy from hydrocephalus is a significant concern in patients with DWS. A better understanding of the causes of subnormal vision and the ophthalmic manifestations of DWS may prevent unnecessary ancillary tests in patients with abnormal vision and may help better categorize the pathogenesis of this disease. The late embryonic period is critical for the development of the retina and central nervous system (which both embryologically originate from neuro-ectoderm), with developmental arrest in this period being hypothesized to be the cause of DWS. DWS and some retinal degenerations (including some variants of retinitis pigmentosa) have been classified as ciliopathies, a relatively recent disease categorization.7–9 Most of the pathologic alternations that have been categorized take place at the cilium-centrosome complex, which is the universal system for managing external signals and cellular detection.7
Fig. 1 — Optical coherence tomogram of the macula of the right (A) and left (B) eye with corresponding scanning laser ophthalmoscopy photographs which demonstrate the preservation of the inner retinal layers in the foveal centers in addition to vessels that abnormally cross the foveal pit. There is no disruption in ellipsoid zone. CAN J OPHTHALMOL — VOL. ], NO. ], ] 2017
1
Case Report Interestingly, Tranos et al. observed bilateral macular edema in a patient with DWS,3 which is not unlike what is seen in patients with retinitis pigmentosa. The possible role of cilia in the pathogenesis of foveal hypoplasia may represent a novel and yet unexplored mechanism of disease that could be the basis for future study.
The authors have no proprietary or commercial interest in any materials discussed in this article.
Disclosure:
Nazanin Ebrahimiadib, MD,* Siamak Karkheiran, MD,† Ramak Roohipoor, MD,* Reza Karkhaneh, MD,* Bobeck S. Modjtahedi, MD‡ *Eye
Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran; †Department of Neurology, Rasool Akram Hospital, Iran University of Medical Sciences, Tehran, Iran; ‡Department of Ophthalmology, Southern California Permanente Medical Group, Baldwin Park, Calif. Correspondence to: Bobeck S. Modjtahedi: [email protected]
2
CAN J OPHTHALMOL — VOL. ], NO. ], ] 2017
REFERENCES 1. Jha VC, Kumar R, Srivastav AK, Mehrotra A, Sahu RN. A case series of 12 patients with incidental asymptomatic Dandy-Walker syndrome and management. Childs Nerv Syst. 2012;28:861-7. 2. Thomas MG, Kumar A, Mohammad S, et al. Structural grading of foveal hypoplasia using spectral-domain optical coherence tomography a predictor of visual acuity? Ophthalmology. 2011;118:1653-60. 3. Tranos P, Dervenis N, Kiouras S. Bilateral macular edema: a new ocular feature of Dandy-Walker syndrome [Epub ahead of print]. Semin Ophthalmol. 2016. 4. Sakurai E, Shirai S, Ozeki H, Majima A. [A case of nonrhegmatogenous retinal detachment in Dandy-Walker Syndrome]. Nippon Ganka Gakkai Zasshi. 1996;100:832-6. 5. Rusu I, Gupta MP, Patel SN, Oltra E, Chan RV. Retinal vascular nonperfusion in siblings with Dandy-Walker variant. J AAPOS. 2016;20:174-7. 6. de Crecchio G, Cennamo G, de Leeuw N, et al. Severe myopia with unusual retinal anomalies and Dandy-Walker sequence in two sibs. A distinct new neuro-ocular disorder. Ophthalmic Genet. 2013;34:254-7. 7. Hildebrandt F, Benzing T, Katsanis N. Ciliopathies. N Engl J Med. 2011;364:1533-43. 8. Badano JL, Mitsuma N, Beales PL, Katsanis N. The ciliopathies: an emerging class of human genetic disorders. Annu Rev Genomics Hum Genet. 2006;7:125-48. 9. Baker K, Beales PL. Making sense of cilia in disease: the human ciliopathies. Am J Med Genet C Semin Med Genet. 2009;151C:281-95. Can J Ophthalmol 2017;]:]]]–]]] 0008-4182/17/$-see front matter & 2017 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jcjo.2017.01.020