Clinical and genetic characterization of patients with eye diseases included in the Spanish Rare Diseases Patient Registry.

BACKGROUND: The low prevalence of rare diseases poses a significant challenge in advancing their understanding. This study aims to delineate the clinical and genetic characteristics of patients with rare eye diseases (RED) enrolled in the Spanish Rare Diseases Patient Registry. METHODS: A total of 864 patients from the registry database were included. Diseases were categorized into inherited retinal dystrophies (n=688); anterior segment diseases (n=48); congenital malformations (n=27); and syndromic diseases with ocular involvement including muscular (n=46), neurological (n=34), or metabolic (n=13); inflammatory diseases (n=4); and tumors (n=4). Data on visual acuity (VA) and/or visual field (VF), symptoms and signs, concurrent diseases in syndromic cases, age of onset and at diagnosis, affected genes, disability rating, inability to work and dependency grade recognition were collected. RESULTS: A mean diagnostic delay of 7 years from symptom onset was observed. Commonly reported symptoms included photophobia, night blindness, and progressive vision loss (≥57% of patients). Cataract was the most prevalent secondary disease (46%), with pseudophakia being the most common ocular surgery (26%). Hearing loss and cardiovascular diseases were the most prevalent concurrent systemic diseases (≥13%). Certificates of disability, incapacity for work, and dependency were held by 87%, 42%, and 19% of patients, respectively. Among the 719 patients with available VA data, 193 (27%) were blind, and 188 (26%) had moderate to severe visual impairment. Over half of the patients (54%) exhibited VF defects, and 216 (25%) had concentric contraction ≤5° or abolished VF. Most had genetic diseases with autosomal recessive (55%), autosomal dominant (30%), X-linked (9%), and mitochondrial (6%) patterns. One patient had mutations in both recessive USH2A and dominant RHO genes simultaneously. Of the 656 patients (75.7%) who underwent genetic testing, only 461 (70.3%) received a positive result (pathogenic or likely pathogenic mutations explaining the phenotype). We found 62 new gene variants related to RED not previously reported in databases of genetic variants related to specific phenotypes. CONCLUSIONS: This study delineates the clinical and genotypic profiles of RED in Spain. Genetic diseases, particularly retinal disorders, predominate, but a significant proportion of affected patients remain genetically undiagnosed, hindering potential gene therapy endeavors. Despite notable improvements in reducing diagnosis delays, it is still remarkable. RED frequently lead to disability and blindness among young populations.

Prevention of retinal ganglion cell swelling by systemic brimonidine in a rat experimental glaucoma model.

BACKGROUND: The objective of this study was to evaluate the neuroprotective effect of brimonidine on retinal ganglion cells in rats with elevated intraocular pressure and to characterize the subpopulation of cells that can be rescued, as well as assess the effect of this drug on retinal ganglion cell soma size. METHODS: Episcleral vein cauterization was used to increase intraocular pressure for 5 weeks on left eyes, considering right eyes as intrinsic controls in all cases. All the animals were then given weekly intraperitoneal injections, the experimental group receiving brimonidine, and the control group were administered only phosphate-buffered saline. Surviving retinal ganglion cells were quantified and their area and distribution measured by retrograde labelling with fluorogold. RESULTS: Brimonidine administered systemically has a neuroprotective effect on retinal ganglion cells, which is unrelated to its capacity to lower intraocular pressure. It prevents the increase of cell size that is associated with stages prior to cell death. This phenomenon is particularly evident in the zones of the retina most susceptible to the damage caused by glaucoma (middle and periphery). CONCLUSION: This effect of preventing retinal ganglion cell swelling can be considered as a new marker to study neuroprotection from antiglaucomatous drugs in the early stages of neurodegeneration in glaucoma.

Animal models and different therapies for treatment of retinitis pigmentosa.

Retinitis pigmentosa (RP) is a heterogeneous group of retinal degenerative diseases initially affecting the rod photoreceptor. Patients present with night blindness, loss of peripheral vision and finally the loss of central vision, as a consequence of death of cone photoreceptors. RP is a genetic disease, showing inheritance of autosomal dominant (AD), autosomal recessive (AR) or X-linked (XL) recessive traits, although some patients have no family history of RP (simplex RP). Many animal models of RP are available and have led to a better understanding of the pathology of the disease, and to the development of therapeutic strategies aimed at curing or slowing down the genetic disorder. In this review, we describe the selected animal models (natural and transgenic) and their phenotypes and genotypes, as well as the advantages and disadvantages of the use of each animal. Also, we look at different therapeutic strategies being studied worldwide and report the latest results. Nevertheless, many obstacles will have to be overcome before most of these strategies can be applied to humans.