Cone Dystrophy, Peripheral

Clinical Characteristics
Ocular Features: 

Several families have been reported in which rod function was normal while cone function was impaired, more so peripherally than centrally.  Visual acuity ranges from normal to 20/200.  Color vision may be normal in some patients while others have some degree of dyschromatopsia.  Full-field ERG cone responses are reduced significantly but focal macular cone ERGs are normal.   Visual fields are normal except for small paracentral scotomas.  Temporal pallor has been noted in the optic discs of 2 patients.  Cone responses on ERG were demonstrated to decrease in one patient during a 4 year interval.  Photophobia as commonly seen in cone-rod dystrophies was not reported.  No abnormalities are seen on fundus examination or fluorescein angiography. 

Systemic Features: 

No systemic disease has been reported. 

Genetics

No responsible mutation has been reported.  Two of the three reported patients were siblings born to presumably unaffected parents, compatible with autosomal recessive inheritance. 

It is questionable whether a 'pure' cone dystrophy exists as most patients have evidence (at least eventually) of both rod and cone disease.  However, an autosomal dominant form of cone dystrophy (602093) has been reported in which cone dysfunction predominates and evidence of rod damage occurs much later.

Treatment
Treatment Options: 

No treatment is available but visual function can be enhanced with low vision aids.  

References
Article Title: 

Peripheral cone disease

Pinckers A, Deutman AF. Peripheral cone disease. Ophthalmologica. 1977;174(3):145-50.

PubMed ID: 
854266

References

Kondo M, Miyake Y, Kondo N, Ueno S, Takakuwa H, Terasaki H. Peripheral cone dystrophy: a variant of cone dystrophy with predominant dysfunction in the peripheral cone system. Ophthalmology. 2004 Apr;111(4):732-9.

PubMedID: 15051206

Pinckers A, Deutman AF. Peripheral cone disease. Ophthalmologica. 1977;174(3):145-50.

PubMedID: 854266