Pigmented Paravenous Chorioretinal Atrophy

Clinical Characteristics
Ocular Features: 

This is a rare type of pigmentary retinopathy with few symptoms in many patients.  Pigment clumps in the form of bone spicules in a paravenous distribution appear as young as 1 year of age and may be present congenitally.  The pigment may begin peripherally and is often segmental but eventually progresses centrally along with chorioretinal atrophy involving the majority of the fundus.  For unknown reasons, males are more severely affected than females.  In one family the retinal changes were associated with hyperopia, esotropia and vitreous degeneration (cells and liquefaction).  There is considerable variation in expressivity among patients and the vision and fundus pigmentation can be highly asymmetrical in the two eyes.  ERG abnormalities likewise vary widely with decreased photopic responses in some individuals and complete lack of both scotopic and photopic responses in severely affected eyes.  Decreased night vision is not a symptom.

This is generally considered to be a stationary condition but long term follow up reveals progression of pigmentary changes, chorioretinal atrophy and increasing constriction of the peripheral visual field.  Symptoms of decreased vision may be noted as early as 3 months of age.  Some patients retain vision of 20/20 or 20/30 into midlife whereas others in the first decade already have count fingers vision.  Likewise the size of the visual field varies widely and is not correlated with age.

Systemic Features: 

No systemic abnormalities have been reported.

Genetics

This is an autosomal dominant disorder caused by heterozygous mutations in the crumbs homolog 1 (CRB1) gene (1q31.3).

CRB1 mutations have been identified in other retinal disorders including nanophthalmos with retinitis pigmentosa, pigmented paravenous chorioretinal atrophy (172870), retinitis pigmentosa-12 (600105), and Leber congenital amaurosis 8 (613835).  No consistent retinal phenotype has been found, however.  There is often marked asymmetry between the two eyes and the rate of visual loss varies widely.  Most individuals have some patchy areas of hypoautofluorescence in the posterior pole with variable amounts of pigmentary anomalies from mild speckling to frank bone spicule formation.

   

 

   

 

Treatment
Treatment Options: 

No effective treatment is available although low vision aids are likely to be helpful in selected patients.

References
Article Title: 

References

Tsang SH, Burke T, Oll M, Yzer S, Lee W, Xie YA, Allikmets R. Whole Exome Sequencing Identifies CRB1 Defect in an Unusual Maculopathy Phenotype. Ophthalmology. 2014 May 6. [Epub ahead of print].

PubMedID: 24811962

Choi JY, Sandberg MA, Berson EL. Natural course of ocular function in pigmented paravenous retinochoroidal atrophy. Am J Ophthalmol. 2006 Apr;141(4):763-5.

PubMedID: 16564825

McKay GJ, Clarke S, Davis JA, Simpson DA, Silvestri G. Pigmented paravenous chorioretinal atrophy is associated with a mutation within the crumbs homolog 1(CRB1) gene. Invest Ophthalmol Vis Sci. 2005 Jan;46(1):322-8.

PubMedID: 15623792

Traboulsi EI, Maumenee IH. Hereditary pigmented paravenous chorioretinal atrophy. Arch Ophthalmol. 1986 Nov;104(11):1636-40.

PubMedID: 3778279

Pearlman JT, Heckenlively JR, Bastek JV. Progressive nature of pigmented paravenous retinochoroidal atrophy. Am J Ophthalmol. 1978 Feb;85(2):215-7.

PubMedID: 623193