Stargardt Disease or Stargardt’s Disease or Fundus Flavimaculatus
Stargardt Disease (STGD) is the most common childhood recessively inherited macular dystrophy. The condition has a genetic basis due to mutations in the ABCA4 gene, that encodes a retinal transported protein; it results from the accumulation of visual cycle kinetics-derived byproducts in the retinal pigmented epithelium (RPE) with secondary photoreceptor dysfunction and cellular death.
Stargardt Disease: Prevalence
Stargardt (STGD) accounts for about 7% of all retinal degenerations, grossly affecting 1 per 10.000 individuals. The disease usually manifests itself in early childhood or adolescence, but later onset has also been reported. As with all autosomal conditions, males and females are equally affected. No race predilection has been noted.
Stargardt Disease: Genetics
Stargardt Disease is a genetic disorder. In its typical form (STGD1, OMIM #248200) it is caused by mutations involving the ABCA4 gene, through autosomal recessive homozygous or compound heterozygous transmission. Additionally, autosomal dominant transmission (STGD4, OMIM #603786) is possible, through heterozygous mutations in the PROM1 gene (4p).
Stargardt-like macular dystrophies (STGD3, OMIM #600110) involving dominant mutations in the ELOVL4 gene (6q14.1) present overlapping clinical features but they are not currently classified as typical Stargardt Disease.
Stargardt Disease: Epidemiology
Given the significant carrier frequency for ABCA4 alleles, reaching as much as 5% -10% in the general population, the association between ABCA4 variants and retinal pathology is now broader than previously thought. Indeed, different combinations of ABCA4 alleles are predicted to result in distinct phenotypes, in a continuum of retinal disease manifestations and it appears the severity of disease is deemed inversely proportional to the residual ABCA4 activity.
Stargardt Disease: Etiopathogenesis Pathophysiology
The ATP-binding cassette (ABC) superfamily comprises a broad and heterogeneous group of proteins specialized in the active transport of various substrates across cellular membranes, against a concentration gradient. These substrates include amino acids, small peptides, ions, metals, lipids and fatty acid derivatives, steroids, organic anions, vitamins and drugs, among others.
Stargardt Disease: Clinical Characteristics
Stargardt Disease patients may be asymptomatic but most commonly present bilateral central visual loss, photophobia, color vision abnormalities, central scotomas and slow dark adaptation.
Vision deterioration is rapidly progressive; its age of onset is highly variable, but it most often occurs between childhood and adolescence or early adulthood. At presentation, visual acuity may range between 20/20 and 20/400, with prior visual acuity being frequently normal, and very few patients further deteriorate their vision to counting finger or hand motion level. Interestingly, it seems the visual prognosis is highly dependent on age of disease onset, with patients presenting with significantly compromised vision at an earlier age having poorer outcomes. Patients frequently deny a positive family history.
Stargardt Disease: Diagnosis
Diagnostic evaluation of Stargardt Disease is based on family history, visual acuity, fundus examination, visual field testing, fluorescein angiography, fundus autofluorescence (FAF), electroretinography (ERG) and optical-coherence tomography (OCT). Genetic testing is currently not performed on a routine basis.
Stargardt Disease affects the macula with variable centrifugal expansion. Fundus examination is frequently normal early on the course of disease, even when patients already complain of vision loss. At this stage, the clinical diagnosis of Stargardt may be missed and patients’ complaints can be easily interpreted as functional visual loss.
Fluorescein angiography of a patient with Stargardt Disease demonstrating the “dark choroid” sign caused by blockage of normal choroidal flush by lipofuscin deposition within the RPE. There is a ring of hyperfluorescence in the perifoveal region corresponding to loss of the RPE in that location.
Stargardt Disease: Treatment
Stargardt Disease remains an incurable condition. Current therapeutic options include photoprotection and low-vision aids. Pharmacological slow-down of the visual cycle, gene therapy and other treatment options aim to prevent lipofuscin accumulation and represent prospects of long-term visual rescue.
Vitamin A supplementation has been regarded as a therapeutic option for certain retinal degenerative conditions such as retinitis pigmentosa. However, recent data suggests that in ABCA4-mediated disease, vitamin A supplementation accelerates the accumulation of lipofuscin pigments in the RPE.
Isotretinoin has reportedly been capable of dampening A2E deposition in the RPE of abca4 knockout mice. Considerable side effects associated with chronic intake of isotretinoin prevent its chronic use in humans.
Stargardt Disease is a preferred target for gene replacement therapy.
Medical Αcupuncture can help slow the accumulation of lipofuscin and the byproducts of the optic cycle, increase their lymphatic drainage, limit macular edema and slow the progression of hereditary retinal dystrophy. Therefore, it can act preventively, deterrently, reduce the rate of onset of symptoms and improve the patient’s quality of life.
Sources
https://www.aao.org/disease-review/stargardt-disease-stgd
https://www.aao.org/eye-health/diseases/what-is-stargardt-disease
https://pubmed.ncbi.nlm.nih.gov/34474141/ (2022)
https://pubmed.ncbi.nlm.nih.gov/31056882/ (2019)
https://pubmed.ncbi.nlm.nih.gov/30141294/ (2018)
https://pubmed.ncbi.nlm.nih.gov/28725294/ (2017)
https://pubmed.ncbi.nlm.nih.gov/18767593/ (2008)
https://pubmed.ncbi.nlm.nih.gov/27459518/ (2008)
Acupuncture Referrences
Acupuncture for retinitis pigmentosa: study protocol for a randomised, sham-controlled trial (2021)
Hui Huang 1 2, Jing Wang 1, Haoran Li 1 2, Ruxue Lei 1 2, Weiwen Zou 1 2, Qun Huang 1, Na Gao 1, Yanlin Zheng 3 2
[Systematic Review of the Application of Complementary and Alternative Medicine and their Potential Therapeutic Benefits in the Treatment of Ophthalmology Patients] (2018)
A K Welte 1, U Hahn 1, A Büssing 2, F Krummenauer 1
Non-neglectable therapeutic options for age-related macular degeneration: A promising perspective from traditional Chinese medicine (2022)
Yuli Li 1, Xing Li 2, Xiaoya Li 1, Zhihong Zeng 3, Niall Strang 4, Xinhua Shu 5, Zhoujin Tan 6
[Acupuncture of intraorbital and extraorbital acupoints reduces apoptosis of retinal ganglion by down-regulating expression of Caspase-3 and ratio of Bax/Bcl-2 in rabbits with nonarteritis anterior ischemic optic neuropathy]
Zi-Yu Tian 1, Shu-Min Li 1, Hui Guo 2, Rong-Rong An 1, Wen-Jia Yuan 1, Yan Meng 1, Peng Bai 1, Ying Wang 3 (2019)