Helicoid Peripapillary Chorioretinal Degeneration
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Disease Entity
Helicoid Peripapillary Chorioretinal Degeneration (HPCD; also known as Sveinsson Chorioretinal Atrophy) is a rare inherited degeneration of the choroid, retinal pigment epithelium (RPE), and retina.
First Description
HPCD was first described by Sveinsson in 1939 as “choroiditis areata” in 4 patients ages 4-25, two of whom were mother and son.1 Sveinsson noted “tongues” of atrophy extending from the disc, not tracking with the vessels, with a notable lack of inflammation (although initially named “choroiditis”).1 The disease received its current name in 1961.2
Epidemiology and Genetics
First and most frequently described in Icelandic families, HPCD has also been described in patients in Serbia and China.3,4 The disease is very rare, and incidence has not been quantified.
The disease is inherited in an autosomal dominant manner, resulting from a missense mutation (Y421H) in the transcriptional enhancer TEAD1, on chromosome 11p15.5 This mutation occurs in a binding site for YAP65, a cofactor expressed in human retina. Although TEAD1 is expressed in many other tissues, there are no known systemic or extraocular manifestations of this disease; the reasons for this remain unknown.6 To date, no patients have been identified with a homozygous TEAD1 mutation.6
Pathophysiology
Histologically, in affected areas of atrophy, the sensory retina, RPE, choriocapillaris, and choroid are absent.6 The optic nerve is also found to be slightly smaller than normal in affected patients.6 There is a lack of inflammatory cells seen (Jonasson). At transition zones, only the RPE and photoreceptor outer segments are affected, suggesting that these tissues may be the primary site of disease.6
While the causative gene has been identified, the mechanism of atrophy has yet to be elucidated; given that TEAD1 is a transcription enhancer gene and that the mutation occurs in a binding site between TEAD1 and YAP65, it is likely that the transcription of structural genes in the retina is affected, leading to a lack of RPE and photoreceptor development in affected peripapillary areas.5,6 Prior to identification of its genetic cause, the disease was proposed to cause tearing of the RPE and Bruch’s membrane away from the optic nerve.7
Clinical Features and Diagnosis
HPCD is a clinical diagnosis based on the characteristic clinical appearance on dilated fundus exam; the diagnosis can be confirmed with genetic testing. The disease is characterized, as its name suggests, by chorioretinal atrophy in a “helicoid” distribution surrounding the optic nerve. These “tongues” of atrophy can approach the fovea, and they do not follow or correlate with the retinal vessels.
Patients can present either asymptomatically or with notable scotomas or blurred vision. Fundus autofluorescence demonstrates peripapillary hypoautofluorescence.4 Fluorescein angiography demonstrates hyperfluorescence due to window defect in the areas of chorioretinal atrophy,3 and full-field electroretinogram demonstrates depressed scotopic and photopic responses, ranging widely from normal to severely abnormal.8,9 Visual field testing demonstrates visual field defects in the areas of atrophy.2
In the past, two forms of the disease had been proposed, with a congenital nonprogressive form and a progressive form (which may have actually been serpiginous choroiditis; however, it is now largely thought that the disease presents early in childhood and may slowly progress throughout life.2,6
Management
Visual prognosis is varied and dependent on the macular extent of atrophy, with patients documented in the literature with anywhere from 20/20 to count fingers vision.3,9 Management is supportive, with no known therapeutic interventions.
One case of choroidal neovascularization (CNV) in a patient with HPCD has been described; in this case, the CNV subsided with 1-2 injections of ranibizumab in each eye.10
References
1. Sveinsson. Chorioiditis Areata. Acta Ophthalmologica 1939;17:73–80.
2. Franceschetti A. A curious affection of the fundus oculi: helicoid peripapillar chorioretinal degeneration. Its relation to pigmentary paravenous chorioretinal degeneration. Doc Ophthalmol 1962;16:81–110.
3. Milenković S, Kosanović-Jaković N, Djurić S, et al. Helicoidal peripapillary degeneration. Eye (Lond) 2005;19:917–920.
4. Shen C, Hu Y, Du M, et al. Analysis of helicoidal peripapillary chorioretinal degeneration progression in an elderly Chinese female patient. Can J Ophthalmol 2018;53:e79–e81.
5. Fossdal R, Jonasson F, Kristjansdottir GT, et al. A novel TEAD1 mutation is the causative allele in Sveinsson’s chorioretinal atrophy (helicoid peripapillary chorioretinal degeneration). Human Molecular Genetics 2004;13:975–981.
6. Jonasson F, Hardarson S, Olafsson BM, Klintworth GK. Sveinsson Chorioretinal Atrophy/Helicoid Peripapillary Chorioretinal Degeneration: First Histopathology Report. Ophthalmology 2007;114:1541–1546.
7. Brazitikos PD, Safran AB. Helicoid peripapillary chorioretinal degeneration. Am J Ophthalmol 1990;109:290–294.
8. Eysteinsson T, Jónasson F, Jónsson V, Bird AC. Helicoidal peripapillary chorioretinal degeneration: electrophysiology and psychophysics in 17 patients. Br J Ophthalmol 1998;82:280–285.
9. Kumar V, Trehan H, Goel N. Sveinsson Chorioretinal Atrophy: Helicoid Peripapillary Chorioretinal Degeneration. JAMA Ophthalmol 2017;135:e173236.
10. Triantafylla M, Panos GD, Dardabounis D, et al. Helicoid peripapillary chorioretinal degeneration complicated by choroidal neovascularization. Eur J Ophthalmol 2016;26:e30-31.
