Pattern Dystrophy

Pattern Dystrophy of the Retinal Pigment Epithelium is a group of rare, inherited eye conditions that affect the macula, the central part of the retina responsible for sharp, detailed vision. In these conditions, a waste material called lipofuscin builds up in a layer of cells beneath the retina, forming various patterns that doctors can see during an eye exam. These patterns might look like a butterfly, a fishing net, or scattered flecks. Most people with pattern dystrophy do not notice any vision problems until they are in their 30s, 40s, or 50s. When symptoms do appear, they are usually mild, such as slightly blurred central vision or straight lines appearing wavy. Because it happens later in life and affects the macula, it is sometimes mistaken for age-related macular degeneration (AMD). However, pattern dystrophy usually progresses much more slowly than AMD. While there is currently no cure for pattern dystrophy, the long-term outlook for vision is generally good. Most people retain enough vision to read and drive for many years. In some cases, abnormal blood vessels can grow under the retina or the central vision can slowly decline over time. Regular eye exams are important to monitor the condition and treat any complications that may arise.

Condition category: Macular Dystrophy

Prevalence: Not precisely known, but considered rare.

Inheritance patterns: Autosomal Dominant

Age of onset: Typically presents in the fourth to fifth decades of life (30s to 50s), though some patients may be diagnosed earlier or later.

Clinical overview: Pattern Dystrophy of the Retinal Pigment Epithelium (RPE) encompasses a heterogeneous group of slowly progressive, primarily autosomal dominant macular diseases. These conditions are characterized by the bilateral accumulation of pigment and lipofuscin deposits within the RPE of the macula. Based on the distribution and appearance of these deposits, pattern dystrophies are classically divided into five main subtypes: adult-onset foveomacular vitelliform dystrophy, butterfly-shaped pigment dystrophy, reticular dystrophy, multifocal pattern dystrophy simulating Stargardt disease, and fundus pulverulentus. (OMIM: 169150, 179605; Orphanet: 99003). Clinically, pattern dystrophies often present in mid-adulthood with mild visual disturbances, such as metamorphopsia or a slight decrease in central vision. Because the onset and appearance can mimic age-related macular degeneration (AMD), pattern dystrophies are frequently misdiagnosed in older patients. However, distinguishing between the two is crucial, as pattern dystrophies generally have a more favorable visual prognosis and do not respond to standard AMD treatments unless secondary complications arise. The underlying pathophysiology involves dysfunction of the photoreceptor outer segments, leading to the accumulation of lipofuscin in the RPE. While the visual prognosis is typically good, patients are at risk for slowly progressive central vision loss due to RPE atrophy, as well as sudden vision loss from complications like choroidal neovascularization. Accurate diagnosis relies on a combination of clinical examination, multimodal imaging, and genetic testing.

Patient and family guide: Pattern Dystrophy of the Retinal Pigment Epithelium is a group of rare, inherited eye conditions that affect the macula, the central part of the retina responsible for sharp, detailed vision. In these conditions, a waste material called lipofuscin builds up in a layer of cells beneath the retina, forming various patterns that doctors can see during an eye exam. These patterns might look like a butterfly, a fishing net, or scattered flecks. Most people with pattern dystrophy do not notice any vision problems until they are in their 30s, 40s, or 50s. When symptoms do appear, they are usually mild, such as slightly blurred central vision or straight lines appearing wavy. Because it happens later in life and affects the macula, it is sometimes mistaken for age-related macular degeneration (AMD). However, pattern dystrophy usually progresses much more slowly than AMD. While there is currently no cure for pattern dystrophy, the long-term outlook for vision is generally good. Most people retain enough vision to read and drive for many years. In some cases, abnormal blood vessels can grow under the retina or the central vision can slowly decline over time. Regular eye exams are important to monitor the condition and treat any complications that may arise.

Symptoms and clinical features: In the early stages, pattern dystrophies are typically asymptomatic. The characteristic pigmentary changes in the macula are often discovered incidentally during a routine eye examination. Patients usually maintain normal visual acuity and color vision during their first few decades of life. As the disease progresses to the intermediate stage, typically in the fourth or fifth decade, patients may begin to experience mild visual symptoms. The most common presenting symptoms are a slight decrease in central visual acuity and metamorphopsia (distortion of straight lines). Some patients may also report mild photophobia or difficulty adapting to dark environments, though these are less common. In the advanced stages, which may occur in the sixth decade and beyond, the accumulation of lipofuscin and subsequent RPE dysfunction can lead to atrophic changes in the macula. This results in a more noticeable and progressive decline in central vision. Additionally, a small percentage of patients may experience sudden, severe vision loss due to the development of choroidal neovascularization (CNV) or a macular hole.

Molecular pathology: Pattern dystrophies are primarily caused by mutations in the PRPH2 gene, which encodes peripherin-2, a cell surface glycoprotein found in the outer segment discs of both rod and cone photoreceptors. Peripherin-2 functions as an adhesion molecule essential for the formation, stabilization, and compaction of these outer segment discs. It forms complexes with other proteins, such as ROM1, to maintain the structural integrity of the photoreceptor membranes. Mutations in PRPH2, particularly those affecting cysteine residues involved in intramolecular disulfide bonds (e.g., Cys213), disrupt the normal folding and function of peripherin-2. This structural instability leads to the degeneration of photoreceptor outer segments. The defective outer segments are shed and phagocytosed by the retinal pigment epithelium (RPE), but the RPE is unable to efficiently process this abnormal material. Consequently, lipofuscin and other waste products accumulate within the RPE cells, leading to the characteristic pigmented deposits seen clinically and eventually causing RPE dysfunction and atrophy.

Genetics: Pattern dystrophies are primarily inherited in an autosomal dominant manner. The most commonly implicated gene is PRPH2 (also known as RDS), located on chromosome 6p21.1. Over 90 different mutations in PRPH2 have been identified, including missense mutations (e.g., Arg172Trp, Cys213Arg, Cys250Phe) and nonsense mutations. Other genes associated with pattern dystrophy phenotypes include BEST1, ABCA4, CTNNA1, IMPG1, and OTX2. There is significant genetic heterogeneity and variable expressivity in pattern dystrophies. A single pathogenic variant in the PRPH2 gene can cause different phenotypic patterns within the same family, and even within the same individual, one pattern may evolve into another over time. Furthermore, PRPH2 mutations can also cause other retinal dystrophies, such as retinitis pigmentosa and cone-rod dystrophy, highlighting the complex genotype-phenotype correlations in these conditions.

Diagnostic evaluation: Diagnosis of pattern dystrophy is primarily clinical, based on the characteristic pattern of pigment deposition in the RPE. Fundoscopy reveals various patterns of yellowish or pigmented material in the macula, such as a butterfly shape, reticular network, or multifocal flecks. Optical coherence tomography (OCT) is crucial for localizing the deposits, which typically appear as highly reflective material between the RPE and the sensory retina, and for monitoring foveal thinning or the development of macular holes. Fluorescein angiography (FA) is highly valuable for differentiating pattern dystrophies from other conditions. It typically shows hypofluorescence corresponding to the pigmented lesions, often surrounded by a ring of hyperfluorescence. Fundus autofluorescence (FAF) reveals areas of increased and decreased autofluorescence corresponding to lipofuscin accumulation and RPE atrophy. Electrophysiological testing, such as electroretinography (ERG), is usually normal, while the electro-oculogram (EOG) may be normal or subnormal depending on the extent of RPE involvement. Genetic testing can confirm the diagnosis by identifying pathogenic variants in the PRPH2 gene or other associated genes. Differential diagnosis includes age-related macular degeneration (AMD), Stargardt disease (especially for the multifocal pattern), and Best disease (for the adult-onset foveomacular vitelliform type). The absence of a dark choroid on FA helps distinguish multifocal pattern dystrophy from Stargardt disease.

Differential diagnosis: Differential diagnosis of pattern dystrophy includes: (1) Age-related macular degeneration — older onset, drusen, no butterfly pattern. (2) Best disease — vitelliform lesion, markedly abnormal EOG. (3) Stargardt disease — flecks, dark choroid, younger onset. (4) Central serous chorioretinopathy — serous detachment, male predominance, stress association. (5) Adult-onset foveomacular vitelliform dystrophy — round yellow lesion, mildly abnormal or normal EOG. (6) Chloroquine/hydroxychloroquine toxicity — bull's-eye maculopathy, medication history.

Natural history: Pattern dystrophies are generally slowly progressive conditions. Patients typically remain asymptomatic during the first few decades of life. In the fourth or fifth decade, they may begin to experience mild visual symptoms, such as slight blurring or metamorphopsia. The characteristic macular lesions may slowly enlarge or change pattern over time. As the disease progresses into later decades, some patients develop atrophic changes in the RPE, which can lead to a more significant decline in central visual acuity. The rate of visual decline is usually slow, but sudden vision loss can occur if secondary complications, such as choroidal neovascularization (CNV) or macular holes, develop. Overall, the visual prognosis is relatively good compared to many other inherited retinal diseases, with many patients retaining reading vision well into their later years.

Management and treatment research: ### Current Management and Monitoring There is no treatment that removes lipofuscin deposits—pigment material that can accumulate in retinal cells—or reliably stops the underlying progression of pattern dystrophy. Care focuses on monitoring vision, treating complications when they occur, and supporting daily activities. - Regular visits with an ophthalmologist or retinal specialist help identify changes over time. Monitoring may include: - **Optical coherence tomography (OCT):** cross-sectional retinal imaging that can identify fluid, thinning, or other macular changes. - **Fundus photography and fundus autofluorescence:** imaging that documents retinal pigment epithelium (RPE) changes. The RPE is a supportive cell layer beneath the light-sensing retina. - Visual-acuity testing and, when appropriate, visual-field testing. - Follow-up timing depends on symptoms and retinal findings. New distortion, a dark or blurry central spot, flashes, or a sudden change in vision should be reported promptly. - Low-vision rehabilitation can be helpful when central vision is reduced. Options may include magnifiers, high-contrast materials, specialized lighting, electronic visual aids, and training in adaptive strategies. ### Treatment of Complications Some people with pattern dystrophy develop **choroidal neovascularization (CNV)**, where abnormal blood vessels grow beneath or within the retina. These vessels may leak fluid or blood and can cause a relatively sudden decline in central vision. - CNV is commonly treated with injections into the eye of medicines that block **vascular endothelial growth factor (VEGF)**, a signal involved in abnormal blood-vessel growth. - Anti-VEGF treatment can manage CNV but does not correct the underlying inherited retinal condition. - In the uncommon event of a full-thickness macular hole, a retinal specialist may consider vitrectomy surgery. ### Approved Disease-Modifying Therapies There are currently no approved gene therapies or other disease-modifying treatments specifically for pattern dystrophy, including PRPH2-associated pattern dystrophy. ### Investigational Therapies There are no current treatment-pipeline entries specifically for pattern dystrophy. Research in inherited retinal diseases includes gene-based therapies, medicines intended to protect retinal cells, and approaches that may address RPE dysfunction. However, these approaches have not been established as treatments for pattern dystrophy. Two early-phase studies in broader inherited and degenerative retinal disease populations are listed as active but not recruiting: - **NCT07341919** — Study of subtenon autologous platelet-rich plasma, given around the eye. This Phase 1/2 study is not recruiting. - **NCT07348588** — Study of intravitreal adalimumab, a medicine injected into the eye. This Phase 1/2 study is not recruiting. These studies are not specific to pattern dystrophy, and their potential relevance to an individual with pattern dystrophy is uncertain. ### Clinical Trial Participation No recruiting interventional clinical trial specifically for pattern dystrophy is listed in the current data. Broader registries and natural-history studies may be relevant, particularly for people with a confirmed genetic diagnosis: - **NCT05589714** — *Universal Rare Gene Study*, a recruiting registry and natural-history study of retinal dystrophies associated with rare disease-causing genetic variants. - **NCT07085533** — A recruiting natural-history study of inherited retinal diseases. Natural-history studies follow participants over time to better understand how a condition changes. They generally do not provide an experimental treatment. Eligibility may depend on genetic test results, diagnosis, age, and retinal findings. A retinal specialist or genetic counselor can help determine whether genetic testing, a registry, or a research study may be appropriate.

Outlook: The overall visual prognosis for patients with pattern dystrophy is generally favorable. Most individuals maintain good central vision (often 20/40 or better) in at least one eye throughout their lives. The progression of the disease is typically slow, allowing patients to adapt to gradual changes in their vision. However, quality of life can be affected by the development of metamorphopsia or a slow decline in reading ability. In a minority of cases, severe vision loss can occur due to the development of geographic atrophy or choroidal neovascularization. Regular monitoring is essential to detect and manage these complications promptly. Low vision aids and rehabilitation can be beneficial for those who experience significant visual impairment.

Epidemiology: Pattern dystrophies are rare, but exact prevalence figures are difficult to determine due to frequent misdiagnosis as age-related macular degeneration. One regional study in northern France estimated the prevalence of pattern dystrophies to be approximately 1 in 1,490 individuals, suggesting over 300,000 affected individuals in greater Europe. The adult-onset foveomacular vitelliform dystrophy subtype has an estimated prevalence ranging from 1 in 7,400 to 1 in 8,200. The condition affects both sexes equally and has been reported across various ethnic groups.

Selected references: 1. Ahmed H, et al. Retinal Pattern Dystrophy. StatPearls [Internet]. 2023. PMID: 32809581 2. Rostamizadeh M, et al. Pattern Dystrophies. EyeWiki. 2024. 3. Ozkaya A, et al. Clinical and imaging findings of pattern dystrophy subtypes. J Fr Ophtalmol. 2018. PMID: 29555321 4. Al-Khuzaei S, et al. Genotype-Phenotype Correlations in PRPH2 Retinopathies. Int J Mol Sci. 2025. PMID: 38256071 5. Jeffery RCH, et al. Retinal Dystrophies Associated With Peripherin-2. Invest Ophthalmol Vis Sci. 2024. PMID: 38451521 6. Chakraborty D, et al. Novel molecular mechanisms for Prph2-associated pattern dystrophy. FASEB J. 2020. PMID: 31914632 7. Rahman N, et al. Macular dystrophies: clinical and imaging features, molecular genetics and therapeutic options. Br J Ophthalmol. 2020. PMID: 31645366 8. Chowers I, et al. Adult-onset foveomacular vitelliform dystrophy: A fresh perspective. Prog Retin Eye Res. 2015. PMID: 25681578