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Katrina Norfleet
Posted: 5/8/2017
Emerging trends and hot topics: Presented Monday, May 8 at the ARVO Annual Meeting

Baltimore, Md. ― In their own words, First Authors at the 2017 Annual Meeting of the Association for Research in Vision and Ophthalmology explain their findings. Their abstracts were designated as some of the newest and most innovative research presented on Monday, May 8, 2017.

Anatomy and Pathology/Oncology
#239 - 1735 - A0213. A CRISPR/Cas9-mediated Screen of Candidate Genes in the Regulation of Optic Fissure Closure. 11am.
In normal eye development, the eyes begin as outpouchings from the brain. The tip of each outpouching becomes an eye, whereas the stalks connecting them to the developing brain become the optic nerves. Along the bottom of each structure is a seam called the optic fissure that must close starting at the fifth week of gestation in humans. Improper closure of this seam can result in a condition known as coloboma, which accounts for up to 10% of childhood blindness. Analysis of tissue surrounding the optic fissure during closure revealed a list candidate genes potentially involved in this developmental event. We are investigating the specific roles of these genes by disrupting their expression in zebrafish using CRISPR-Cas9-mediated genome editing technology and screening for coloboma and other eye abnormalities. This study will expand our understanding of the mechanisms behind optic fissure closure, with implications in both the diagnostics and treatment of coloboma.

#240 - 1739 - A0217. Modifying chondroitin sulfate proteoglycans enhances retinal ganglion cell axon regeneration in the mouse optic nerve. 11am.
Vision researchers have shown that modifying a protein in the optic nerve makes it easier for nerve cells to grow back after injury. People with glaucoma can lose vision when cells in their optic nerve thin out over time. In mice where optic nerve cells were damaged, scientists showed that delivering an enzyme which modifies proteins called chondroitin sulfate proteoglycans led to more nerve cells growing longer distances toward the brain. This could help improve treatments that aim to restore sight in people with glaucoma and other conditions causing optic nerve damage.

Biochemistry/Molecular Biology
#213 – 1243. Mutations in the X-linked gene PRPS1 cause retinal degeneration in females. 10am.
Retinal dystrophies are disorders associated with reduced or deteriorating vision in both eyes. Most retinal dystrophies are genetic and are caused by a mistake in a gene that is passed on (inherited) from one or both parents. A pattern of inheritance called X-linked means that the disorder is caused by mistakes in genes on the X chromosome. Males, who have only one X chromosome have an altered copy of the gene in each cell in the retina resulting in the condition. A female (with two X chromosomes) with a mistake in one copy of a gene on the X chromosome is said to be a “carrier” for an X-linked condition. In females generally, mutation in one copy of an X-linked gene is insufficient to cause the condition, or results in a much milder form. Surprisingly, we have identified 5 different families with a mistake in one copy of the gene PRPS1 on the X chromosome, which causes retinal dystrophy in females. Mistakes in this gene have already been shown to cause severe disease in males, however, there were no affected males in our study families, suggesting that the mistakes identified in this gene may be incompatible with life in males.

Clinical/Epidemiologic Research
#287 - 2410 - B0559. Student adherence and satisfaction with eyeglass usage in the Baltimore Reading and Eye Disease Study (BREDS). 3:45pm.
School-based programs have become a popular way to identify vision problems in children and provide eyeglasses. However, some programs have reported that students’ usage of these eyeglasses is low. Our study examined how many students were wearing and were happy with glasses they received from a school-based vision program.

Two pairs of eyeglasses were given to second and third graders who needed them, based on results from an in-school vision exam, and replacements were provided for lost or broken glasses. Children who received glasses were interviewed about their eyeglass usage and attitudes towards wearing glasses later that school year.

We found that of the 320 examined students, 66.4% needed eyeglasses. In follow-up assessments, the majority (87.4%) of students were wearing glasses. 89.4% reported being happy with their glasses and 86.4% believed their glasses looked good on them. 68.2% felt their glasses helped them see “a lot better” and 71.2% felt their glasses helped them read “a lot better.” 20.2% reported being teased about wearing glasses.

Here, glasses usage was higher than reported in previous studies. This may be related to close monitoring and a robust replacement program. Social issues remain an issue, as teasing was reported by one-fifth of students.

#221 - 1463 - B0113. Utility of magnetic nanoparticles for targeted endothelial transplantation in an ex vivo model. 8:30am.
The corneal endothelium is responsible for maintaining corneal clarity and is unable to repair itself when damaged, either through injury or age. Treatment of this cell layer poses great challenges for clinicians due to its location, lack of regenerative potential, and reducing cell population with age. This study investigates the potential of human corneal endothelial cells (HCEC), loaded with iron-based nanoparticles, to be magnetically-directed to injured regions of the endothelium to repair the damaged area.

Eye Movements/Strabismus/Amblyopia/Neuro-Ophthalmology
#285 - 2367 - B0516. Visual acuity and early literacy at 6 - 7 years: A reduction in visual acuity is associated with decreased reading efficiency in school children. 3:45pm.
The research draws on the “Born in Bradford” study of children growing up in the city of Bradford, UK. Around 2000 children across the city have had their eyesight measured as part of local school vision screening programme and have also had an assessment of their early reading ability.

It seems intuitive that poor vision will impact on your ability to learn, but the research evidence is scant. Early literacy is a key indicator for educational attainment in later life, so it is important to understand the effect of poor vision as reading skills develop. We are following up a smaller group of children to find out the impact of poor vision on their reading ability and have found that children with the poorest vision had a reduction in their literacy scores even taking into account other factors.
This means that children with poor eyesight on school entry will have a reduction in their reading ability and they are likely to struggle to see their books or the board.

#285 - 2364 - B0513. Analysis of a Novel Method for Detection of Vision Disorders in Children Birth to Three Years of Age. 3:45pm.
Vision screenings are regularly conducted on preschool and school-aged children States for detection of significant vision problems, and scientific studies conducted in the past two decades have clearly established the benefits of vision screening. However, in children below three years of age, there is minimal understanding or agreement of how to assess vision effectively in medical as well as early education settings. In this study, a new parent-completed survey based on critical vision-related developmental milestones was tested for its potential in the detection of significant vision problems in children below three years of age. Early detection and treatment of vision problems in young children increase the likelihood of normal development and learning readiness.

#274 - 2097 - A0158. In vivo imaging of human aqueous outflow and calculation of aqueous column diameter. 3:45pm.
Clinicians and scientists from the University of Cambridge have developed a new clinical tool for glaucoma to aid diagnosis, patient selection for surgery and treatment response.

Disruption of aqueous outflow is a hallmark of glaucoma. The non-invasive technique developed by the researchers uses haemoglobin video imaging – or HVI – to examine the interface between blood and aqueous humor in vessels on the surface of the eye. A filter coupled to a high-speed, high-resolution camera enhances the contrast between blood and aqueous, which, together with software to stabilise the micro-movements of the eye, enables detailed observation and reliable quantification in patients that was not previously possible.

In ongoing work, the team are exploring their hypothesis that a reliable clinical tool which can detect impairment of the aqueous drainage system will be useful in assessing patients with glaucoma and guiding therapy in the future.

#274 - 2080 - A0141. Multimodal imaging analysis in patients with transient ocular hypotony after antiglaucomatous surgery. 3:45pm.
Using an eye scan, scientists can now detect early glaucoma surgery complications. Glaucoma surgery aims to reduce ocular pressure to safe levels, but rarely can it lower the pressure exceedingly, potentially harming the eye. The scan device called spectral domain optical coherence tomography allows scientist to generate high-resolution digital images of the back of the eye, which then can be used to detect early structural changes, if the eye pressure gets too low. These finding may help doctors to quickly diagnose these changes, acting before irreversible damage has occurred.

#267 – 2024. A Clinico-Pathological Study of the Structural and Functional Changes to the Retina and Optic Nerve following anti-VEGF Treatments for Diabetic Macular Edema. 3:45pm.
Could a treatment proven to improve vision in diabetic patients also potentially cause long-term harm? To answer this question, thirty-one patients with diabetes who were receiving anti-VEGF injections to reduce swelling in their eyes were followed for two years. Treatment improved their central vision as expected. During that time period, changes were noted to occur in the optic nerve, which is the main nerve that connects the eye to the brain. These changes have not previously been reported as the nerve is not routinely tested in patients undergoing diabetic eye treatment. To examine whether the treatment itself may be potentially harmful to the nerve, an animal model was used. Diabetes was induced in a group of rats who then received injections of the same type of drug used in humans. The drug was observed to have a dose-dependent negative effect on the retina. Retinal eye cells were also removed from the animals and grown in a controlled laboratory setting. It was shown that anti-VEGF treatment appeared to be potentially harmful by decreasing the activity and increasing death of retinal cells. Collectively, these results provide a cautionary note to monitor the nerve status in patients undergoing frequent anti-VEGF treatments.

Retinal Cell Biology
#219 - 1361 - A0382. Exploring mouse retinal ganglion cell diversity within iPSC derived optic cups. 8:30am.
The information from the eye is transferred to the brain through a million of processes, bundled together into the optic nerve. In glaucoma and other optic neuropathies these processes and the cells they are coming from, are damaged. Unfortunately there is no therapy available that can halt the progressive death of these neurons and irreversible loss of sight. In our laboratory we are able to grow these highly specialized retinal ganglion cells within three-dimensional organoids. We have demonstrated that it is possible to manufacture these neurons by millions, establishing a path for transplantation studies. Moreover, donor cells, injected into the mouse eyes, survived and extended long processes, into the host tissue. Encouraged by those first experiments we are now exploring the potential of our stem cell-derived retinal ganglion cells to recover function in experimental models of glaucoma.

#282 - 2273 - B0227. Outcome measures for BEST1 gene augmentation therapy: restoration of RPE-photoreceptor interface homeostasis. 3:45pm.
Our research team has developed the first gene therapy treatment for a juvenile form of macular degeneration, commonly known as Best Disease, caused by mutations in the BEST1 gene. This therapy was successfully tested in the dog model of Best Disease, revealing rapid reversal of macular lesions after a single injection of healthy BEST1 gene into the affected eye. This healthy BEST1 gene replaces the mutated one in the retina, specifically in the retinal pigment epithelium cells, guided by adeno-­‐ associated virus, which proved safe for both the dog and human eyes. To measure the success of this therapy we have developed a set of parameters that will inform us about the rescue of the retinal cells’ architecture and their interrelations. Based on these parameters, we have found that this new therapy is not only safe and effective, but also clearly restores essential relations and physical cell­to‐cell connections in the dog retina. The remarkable recovery of the affected retina was analyzed by non-­‐ invasive imaging and confirmed by molecular methods and microscopy. Further research aimed at understanding these molecular defects and the mechanism of such potent rescue with gene therapy will accelerate progress toward clinical trial for Best Disease patients.

#241 - 1752 - A0363. AAV2-GRP78-mediated gene therapy prevents retinal neuronal injury via downregulation of Tau oligomers. 11am.
When someone suffers a head trauma, sometimes there is damage to the optic nerve that is responsible for passing information between the eyes and the brain. When the optic nerve is injured, it causes the nerve cells to die and results in irreversible vision loss. This type of injury is called traumatic optic neuropathy, or TON. At this point, there is no effective treatment for TON. The endoplasmic reticulum (ER) is a type of organelle in eukaryotic cells for protein synthesis, folding and transportation. Many stressful conditions including the injury of optic nerve disturbs the function of ER and causes protein not properly folded, which causes ER stress and results in cell death. In our study, we introduced a molecular chaperone called GRP78 into optic nerve cells by adeno-associated virus (AAV)-mediated gene delivery and found it eliminates ER stress, prevented optic nerve cell death and preserved optic nerve cells function. Mechanistically, our work further linked the neuronal protective effect of GRP78 to its inhibition of the misfolding and aggregation of Tau protein, which is protein well known to promote neurodegeneration in Alzheimer’s disease. Our study indicates that gene therapy with GRP78 or immunotherapy with an antibody to eliminate misfolded Tau protein may provide novel therapeutic approaches to rescue optic nerve cell from death after axonal injury.

#241 - 1765 - A0376. Single molecule fluorescent in situ hybridization in the mouse retina. 11am.
The retina is an incredibly complex light-detecting tissue at the back of the eye that converts light stimuli into neuronal signals that are sent to the brain. Within the retina are hundreds of different cell types that each express thousands of genes at any given time. In order to unravel this complexity, we need an effective way to visualize where and when genes are expressed in the retina. To accomplish this, we have used a technique called single molecule fluorescence in situ hybridization (smFISH) that allows us to visualize gene expression in the retina at a molecular level. Our technique significantly increases the reliability and resolution of visualizing gene expression in the retina from that of previous methods, while substantially reducing the time and cost. Our smFISH method has broad applications for studying retinal gene expression, including investigating completely novel, uncharacterized genes, studying how gene expression changes in disease states, and understanding how the retina develops from embryo to adult.

#219 - 1369 - A0390. Analysis of Retinal Ganglion Cell Development and Maturation from Human Pluripotent Stem Cells. 8:30am.
A new study demonstrates the ability to use patient-derived stem cells to make the neurons that typically die in blinding disorders such as glaucoma. These patient derived neurons are used to study the development of the disease over time, which helps uncover the underlying disease mechanisms. These cells also allow for the development of personalized therapies and treatments, depending on the individual's genetic background. Moreover, researchers are currently working on ways in which these neurons could be used for cell replacement therapies, which hold promise to restore vision to those with blinding disorders.