Thomas A. Finley
BASICS
DESCRIPTION
• Group of disorders related to macular pigment depositions in the retinal pigment epithelium (RPE) that are usually inherited in an autosomal dominant fashion
• Commonly manifest in the second and third decades of life
• Often found in asymptomatic patients on routine eye exam
• Affected patients may remain asymptomatic until mid- or late-adulthood with presenting symptoms of slightly diminished visual acuity or metamorphopsia.
• Slowly progressive loss of central vision
• Dystrophies may be subdivided into several patterns based on clinical appearance, including the following:
– Butterfly dystrophy
– Reticular dystrophy
– Adult-onset foveomacular vitelliform dystrophy
– Fundus pulverulentus
– Multifocal pattern dystrophy simulating fundus flavimaculatus
• Clinical appearance is variable, may progress to another pattern with time, or even display different patterns between the two eyes of a single patient.
EPIDEMIOLOGY
Incidence
• Unknown due to phenotypic variability
– Males and females affected equally
Prevalence
Unknown due to phenotypic variability
RISK FACTORS
Genetics
• Typically inherited in an autosomal dominant fashion
• Most common genetic association is due to mutations in the RDS/peripherin gene located on the short arm of chromosome 6.
• RDS/peripherin gene codes for a surface glycoprotein expressed in the outer segments of rods and cones.
• More than 90 mutations of the gene are known to exist, resulting in great phenotypic variability.
GENERAL PREVENTION
Genetic counseling
PATHOPHYSIOLOGY
• Various patterns of pigment deposition occur at the level of the retinal pigment epithelium (RPE) in the macula.
• Slow progressive atrophy of the RPE and overlying photoreceptors
• May develop choroidal neovascularization
ETIOLOGY
• The different subdivisions of pattern dystrophy are phenotypic variations of the many mutations that may occur within the RDS/peripherin gene.
COMMONLY ASSOCIATED CONDITIONS
• Most cases are not associated with systemic illness.
• Maternally inherited diabetes and deafness (MIDD) and mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) are frequently associated with pattern dystrophy.
DIAGNOSIS
HISTORY
May be asymptomatic or have complaints of slight decrease in vision or metamorphopsia
PHYSICAL EXAM
• Gray, yellow, or orange pigment accumulations at the level of the RPE in the macula
• Usually symmetric but can show different pigment patterns
DIAGNOSTIC TESTS & INTERPRETATION
Diagnostic Procedures/Other
• Visual fields: normal
• Color vision: normal until late in disease process
• Dark adaptation: normal
• Fluorescein angiography: Hypofluorescence due to pigment figure blocking. Hyperfluorescence due to RPE atrophy associated window defects
• Electroretinogram (ERG): normal
• Electrooculogram (EOG): may show decreased response
• Fundus autofluorescence: fundus may show increased autofluorescence in areas of accumulated lipofuscin, however, may show decreased levels once atrophy of the RPE and overlying photoreceptors develops (1)
Pathological Findings
• Destruction of the RPE and overlying photoreceptor layer with accumulation of lipofuscin within the RPE (2)
DIFFERENTIAL DIAGNOSIS
• Stargardt’s disease
• Age-related macular degeneration
• Dominant drusen
• Cone dystrophy
• Benign concentric annular macular dystrophy
• Medication toxicity
TREATMENT
MEDICATION
No treatment available for Pattern dystrophy (PD)
ADDITIONAL TREATMENT
General Measures
Secondary choroidal neovascular membrane (CNVM) may be treated with photodynamic therapy (PDT) (3)[C] versus vascular endothelial growth factor inhibitors (anti-VEGF) (4)[C] with variable visual results
Issues for Referral
Development of choroidal neovascularization
ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
• Annual examination by ophthalmologist
• Low vision evaluation
PATIENT EDUCATION
http://www.nei.nih.gov/resources/eyegene.asp
PROGNOSIS
• Good prognosis for retaining useful vision throughout life
• Most patients retain reading vision in at least one eye through late adulthood.
COMPLICATIONS
• Central visual loss
• Choroidal neovascularization
REFERENCES
1. Schmitz-Valckenberg S, Holz FG, Bird AC, et al. Fundus autofluorescence imaging: review and perspectives. Retina 2008;28(3):385–409.
2. Zhang K, Garibaldi DC, Li Y, et al. Butterfly-shaped pattern dystrophy: a genetic, clinical, and histopathological report. Arch Ophthalmol 2002;120(4):485–490.
3. Parodi M, Liberali T, Pedio M, et al. Photodynamic therapy of subfoveal choroidal neovascularization secondary to reticular pattern dystrophy: Three-year results of an uncontrolled, prospective case series. Am J Ophthalmol 2006;141(6):1152–1154.
4. Parodi M, Iacono P, Cascavilla M, et al. Intravitreal bevacizumab for subfoveal choroidal neovascularization associated with pattern dystrophy. Invest Ophthalmol Vis Sci 2010;51(9):4358–4361.
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