FOR IMMEDIATE RELEASE
Emerging trends and hot topics: Presented Tuesday, May 3 at the ARVO Annual Meeting
Seattle, Wash. ― In their own words, First Authors at the 2016 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 Tuesday, May 3.
#306 - 2809. Trinucleotide repeat expansion and TCF4 gene expression in Fuchs endothelial corneal dystrophy. Keisuke Ogata. May 3, 8:30am.
Fuchs endothelial corneal dystrophy (FECD) is the most common genetically inherited corneal dystrophy. Though little is known about the genetic background, Wieben et al. from the Mayo Clinic reported that trinucleotide repeat expansion was often observed in transcription factor 4 (TCF4) among FECD patients. The results of our subsequent research, as well as that of other groups, have now confirmed this striking finding. In this study, we examined the genomic DNA of a large number of FECD patients. Our current findings provide additional evidence that trinucleotide repeat expansion in TCF4 is a common genetic background of FECD. In the future, topics such as how trinucleotide repeat expansion causes disease and elucidation of the genetic background of patients without trinucleotide repeat expansion are sure to open novel pathways for the diagnosis and treatment of FECD.
#338 - 3516 - A0119. Anti-Angiogenic Polymer Therapeutic for Corneal Neovascularization. Crystal Shin. May 3, 11am.
A healthy, normal eye is without any blood vessels in the outer transparent layer (cornea) to maintain clear vision. Any assaults to eye surface stimulates blood vessels to grow into the cornea known as the corneal neovascularization (CNV), and results in severe vision loss and blindness, if left untreated. Currently CNV is treated with drug eye drops. Although eye drop treatment is very simple, it is not efficient and must be applied several times in a day, which results in toxic side effects.
For the rapid and effective treatment of CNV, we have developed a novel nanowafer therapeutic using a sugar polymer: dextran sulfate (DS). The nanowafer, a thin and transparent film, is simply applied on the eye like a contact lens. The nanowafer is self-clearing, as it dissolves during drug release and disappears.
We studied the nanowafer efficacy in mice affected with chemical eye injuries. Our studies revealed that nanowafer treatment was twice more effective than drug eye drops in preventing CNV and cloudy eye formation. The development of nanowafer is a major advancement in the effective treatment of eye diseases such as dry eye, glaucoma, eye infections and injuries.
#336 - 3477. Extracellular vesicles derived from human mesenchymal stem cells promote corneal wound repair by increasing epithelial cell proliferation and reducing neovascularisation in a rat corneal alkali burn model. Thomas Ritter. May 3, 11am.
Extracellular vesicles (EV; often referred to as “exosomes”) are tiny packages of cell material that are released by most cell types and are involved in communications between cells. Specifically, EVs can shuttle their molecular “cargo” from the cell of origin to nearby and distant cells. In our study, we purified EVs from mesenchymal stem cells (MSCs), a type of adult stem cell that is known to be capable of promoting tissue regeneration and wound healing in a range of diseases. We then investigated, in an animal model, the effect of directly applying a suspension of MSC-EVs to the surface of the eye after a chemical burn injury. Remarkably, one application of MSC-EVs to the injured eye significantly accelerated the healing of the eye surface and also resulted in more complete repair of all layers of the cornea which must remain completely clear for vision to be preserved. Our work holds promise for direct application of a cell-free regenerative therapy for people with severe chemical burns as well as other forms of injury and disease of the surface of the eye.
#363 - 3783. Bowman’s Layer Acoustic Impedance in Normal and Keratoconus Cornea. Ronald Silverman. May 3, 3:45pm.
Keratoconus is a disease, usually first manifesting in young adults, in which the cornea becomes progressively thinner and bulges to a cone-like shape. With progression a corneal transplant may be required to save the eye. Early identification is crucial so that corneal refractive surgery, which is contraindicated, is avoided and progression can be arrested by crosslinking therapy. Early diagnosis, currently based on surface curvature and corneal thinning, is sometimes ambiguous. In our study, we investigated the stiffness of Bowman’s layer, a part of the cornea implicated in early keratoconus. We developed an ultrasound technique that allows mapping of this parameter and showed how it is altered in keratoconus and in non-symptomatic eyes of patients with unilateral keratoconus. This new approach offers a diagnostic characteristic that may potentially improve certainty in early diagnosis of keratoconus.
#317 - 3078 - B0065. Binocular iPad game treatment for amblyopia is more successful than patching. Krista Kelly. May 3, 8:30am.
Amblyopia (‘lazy eye’) is the leading cause of monocular visual impairment in children. The most common treatment is to patch the stronger eye to force the use of the amblyopic eye, but 20/20 vision is not always achieved and the eyes do not learn to work together. Patching can also be uncomfortable and an emotional burden for the child, resulting in low compliance. Dr. Krista Kelly, a postdoctoral fellow funded by the Thrasher Research Fund, is assessing a novel binocular iPad game treatment for amblyopia and comparing it to patching in a randomized clinical trial at The Retina Foundation of the Southwest. The child can play the iPad game at home while wearing special glasses that separate the images and rebalance the contrast between the two eyes. The child must use both eyes to succeed in the game, and the amblyopic eye gradually becomes stronger. With 2 weeks of treatment, children playing the binocular iPad game improved nearly 2 lines on the eye chart; children who patched improved less than 1 line. Binocular iPad games offer an additional option for amblyopia treatment that is more engaging for the child.
#317 - 3094 - B0081. New Pediatric Vision Screener – Data Analysis and Validation. Boris Gramatikov. May 3, 8:30am.
We have developed an improved pediatric vision screening device that can reliably identify risk factors for amblyopia (“lazy eye”), namely eye misalignment and defocus. Our Pediatric Vision Screener (PVS) is a further development of an earlier instrument that served as a prototype of REBIScan’s Pediatric Vision Scanner. Unlike commercially available vision screening devices, both systems use polarization techniques to detect when both eyes are anatomically aligned with a fixation target. The newer instrument offers additional features such as defocus detection, better attraction of the child’s attention, and improved reliability. In a preliminary study, the PVS allowed reliable separation between normal test subjects and patients with eye misalignment or defocus. We believe that the PVS instrument design, the analysis methods employed, and the device as a whole, will prove valuable for mass screening and will meet the demand for a reliable, automated eye misalignment/defocus screening tool for infants and children at risk for amblyopia or subnormal binocular vision.
#368 - 3819. Detection of Amblyopia in Young Children via Retinal Rivalry Using a Video Game Styled Interface on a Tablet Device. Ryan Gise. May 3, 3:45pm.
Lazy eye or amblyopia occurs in 2 to 3% of children in America and remains the most common cause of visual impairment among children and young adults. Untreated amblyopia can have profound effects later in life should vision in the better-seeing eye become impaired. When caught early, treatment is very successful. The main challenge is early detection. Comparing the difference in brightness between the two eyes in a video game-like test on the iPad, we found in a clinical setting that the test is a very sensitive indicator of lazy eye and the severity of the defect. The test requires no language skills, only the choice between bright and dim images and interaction with a tablet, skills that are easy for even 4-year-old child. Since this is a binocular test, children are unable to “cheat” by memorizing the standard eye chart or “peek” with the good eye, shortcomings of monocular testing. A skilled professional is not required to administer the test which can be quickly administered.
#368 - 3816. Home use binocular dichoptic video content treatment for amblyopia-pilot study. Chaim Stolovitch. May 3, 3:45pm.
#302 - 2778. The yin and yang of the complement cascade in glaucoma – the importance of timing and location. Gareth Howell. May 3, 8:30am.
Glaucoma is characterized by the loss of retinal ganglion cells (RGCs), the output neurons of the retina. We study the role of immune responses during early stages of glaucoma, prior to the death of RGCs. In particular, we have used genome-wide profiling to show that the complement cascade is upregulated in the optic nerve head and retina early after IOP elevation in a mouse model of glaucoma. The complement cascade has been shown to be activated in human and other animal models of glaucoma. Non-neuronal cells such as astrocytes, microglia and infiltrating macrophages express different components of the cascade. Interestingly, activation of some components of the complement cascade appears beneficial while activation of other components appears damaging. Therefore, we are using a combination of genetic and genomic approaches to determine the precise nature of these responses and identify potential new treatments.
#302 - 2781. Citicoline preserves optic nerve integrity and visuomotor function following chronic intraocular pressure elevation. Yolandi van der Merwe. May 3, 8:30am.
Glaucoma is the second leading cause of blindness worldwide. It damages the optic nerve, and leads to progressive loss of vision. Recent studies suggest that citicoline supplements can reduce vision loss in glaucoma patients, but the role citicoline plays in preserving sight remains unclear. In this study, we performed oral citicoline treatment in an experimental glaucoma model of elevated eye pressure in rats, and measured the effects on visual brain protection and vision preservation using magnetic resonance imaging (MRI) and optokinetics, respectively. We found that oral citicoline treatment may have reduced the damage to the optic nerve in the brain and protected vision over time compared to rats with the same experimental glaucoma but with no treatment. Our results go along with recent articles that suggest citicoline can protect the brain and reduce functional loss in diseases where the nerves in the brain are slowly lost.
#313 - 2993 - A0342. Ocular neurovascular changes during head-down posture predict future retinal nerve fiber layer loss in glaucoma suspects. Giacinto Triolo. May 3, 8:30am.
Glaucoma is the second leading cause of blindness worldwide. Many risk factors, such as elevated intraocular pressure (IOP), predict eventual retinal ganglion cell (RGC) death and retinal nerve fiber (RNF) atrophy. Modern diagnostic and therapeutic strategies focus on early detection and treatment of IOP, the principal modifiable risk factor related to glaucoma. While optical coherence tomography (OCT) is used to detect irreversible structural damage of the RGCs and RNFs, the pattern electroretinogram (PERG) is able to measure RGC functional abnormalities. Our previous PERG studies demonstrated that early RGC dysfunction precedes irreversible glaucomatous atrophy, and that this dysfunction may be reversed by IOP-lowering medications. Further, we have reported that head down tilting (HDT) of moderate degree in glaucoma suspects may induce reversible RGC dysfunction, detectable by PERG, along with IOP and systemic blood pressure changes. The present study suggests that those HDT-induced neuro-vascular changes may usefully predict which glaucoma suspects will develop RNF damage after 5 years and, thus, the possibility of earlier detection of incipient and reversible glaucomatous dysfunction. These results are being further investigated in our ongoing NEI-supported clinical trial STOP-RGCD (Stop RGC Dysfunction).
#314 - 3013 - A0362. Mechanical strain modulates TRPV4-dependent cytoskeletal reorganization in the trabecular meshwork. David Krizaj. May 3, 8:30am.
Increase in intraocular pressure (IOP) that results from excessive production or decreased drainage of fluid from the eye represents a primary risk factor for developing glaucoma – the primary cause of irreversible blindness in the world. Drainage takes place mainly through the trabecular meshwork (TM), a cellular sieve through which IOP controls the exit of fluid from the eye. During chronic, pathological IOP elevations TM cells become increasingly rigid and contractile due to stiffening of their internal skeleton which in turn is believed to play a key role in maintaining elevated IOP. We know that disassembling this cytoskeleton lowers IOP and protects against glaucoma, however the drugs that can do this are toxic. It would be better to target the mechanism that drives the cells’ skeleton in response to pressure however this mechanism is unknown. We have now identified a key component to be TRPV4, a mechanosensitive ion channel that senses pressure in the eye. We show that TRPV4 activation recapitulates the effects of elevated IOP on cells’ skeleton whereas suppressing its activation lowers IOP and protects against glaucoma. We also designed new compounds to specifically block the channel in the eye. This offers the promise for a new generation of anti-glaucoma targets. In summary, we identified the mechanosensor that, when overactivated, kills the retina by sustaining elevated IOP through TM cells and we show that targeting it can protect the eye without adverse side effects.
#360 - 3765. Mitochondrial Flavoprotein Fluorescence in Glaucoma Suspects, Primary Open-Angle Glaucoma, and Healthy Controls. Lawrence Geyman. May 3, 3:45pm.
Glaucoma is an insidious eye disease that leads to vision loss only in its later stages. Earlier diagnosis prior to structural changes would greatly benefit millions of patients who could take advantage of available therapies before irreversible tissue damage takes place.
Metabolic dysfunction occurs at the earliest stage and is responsible for the clinical disease which follows. Until recently, all studies on eye metabolism have been limited to animal or cell culture models. A specialized camera system is now able to detect evidence of metabolic dysfunction and has been applied by our research group to noninvasively analyze the metabolic status of known glaucoma patients, those suspected of having undiagnosed glaucoma, and healthy subjects.
Glaucoma suspects were those patients with elevated eye pressure, a risk factor for the development of glaucoma, but no evidence of optic nerve damage or vision loss detectable by current methods. These patients showed a significantly higher level of metabolic dysfunction compared to healthy subjects, suggesting that prior to any visible damage or vision loss, patients with elevated eye pressure may already have the metabolic dysfunction of early glaucoma. This metabolic information may lead to earlier identification of the disease and better management of these patients.
#375 - 3936 - A0222. Clinical validation of a tablet perimeter. Algis Vingrys. May 3, 3:45pm.
Measuring the extent of the visual field is an essential component of eye and neurology clinics being a key component in the detection of many eye and brain diseases. Currently visual field testing is performed using expensive equipment only available in a hospital or doctor’s office. The challenge has been to develop a mobile visual field test that patients can undertake away from the doctor’s office in order to identify or monitor their disease.
At the 2016 Annual Meeting of the Association for Research in Vision and Ophthalmology (ARVO) a team from Melbourne lead by Drs George Kong and Algis Vingrys report on their newly developed visual field test that can be performed on an iPaD tablet; called the Melbourne Rapid Fields (MRF). The MRF was designed to produce an outcome robust to environmental factors and, when applied to a group of glaucoma patients, it gave sound diagnostic outcomes that correlated with the clinical standard, the Humphrey Field Analyzer. The MRF requires 3-4 mins per eye to give repeatable outcomes. This development has the potential to transform visual field examination by allowing testing at a patient’s bedside, at home, in rural or remote areas, or where equipment cannot be financed.
#322 - 3285 - C0085. Ocular Safety of Intravitreal Anti Connective Tissue Growth Factor Neutralizing Antibody. Narsis Daftarian. May 3, 8:30am.
Scar tissue formation inside the eye is the main long-term cause of blindness in the most sight-threatening eye diseases such as diabetic retinopathy and age related macular degeneration. Anti-vascular endothelial growth factor (anti-VEGF) drugs are routinely used via injection into the eye to stop new vessel formation, but they do not prevent the growth of scar tissue inside the eye. Connective tissue growth factor (CTGF) is a protein contributing to scar formation in different tissues including the eye. Our group previously showed that neutralizing this protein through applying an antibody to the eye tissue culture in the laboratory effectively prevented the expression of proteins contributing to scar tissue formation in the eye. In the present study, for the first time, we detected the safe dose of anti-CTGF antibody when injected into the rat eyes. The possible toxic effects of this drug on the eye tissues of rats were also determined.
#346 - 3694 - D0105. Comparative study of different methods for analyzing correlated continuous data. Bernard Rosner. May 3, 11am.
In ophthalmic research, an outcome measurement, e.g., visual acuity, is often obtained from both eyes of a person to evaluate its associations with eye-specific or person-specific characteristics. It is more efficient to use the eye as the unit of analysis, rather than to summarize data for a person, e.g., using the worst eye. This is particularly important if there are eye-specific covariates or if one is looking at change over time where the worst eye may differ at baseline and follow-up. Because outcomes from fellow eyes are usually correlated this requires special methods of regression analysis that account for this correlation. In this poster, we illustrate use of these methods based on software available in major statistical packages.
#346 - 3712 - D0123. Decreased Plasma Levels of Dickkopf-1 in Patients with Exudative Age-related Macular Degeneration. Liu Zhen . May 3, 11am.
Age-related macular degeneration (AMD) is the leading cause of severe and irreversible vision loss in elderly population in developed countries. To date, treatment to restard the progression of the disease does exist. However, there is no early plasma diagnostic marker. The canonical Wnt signaling pathway play an important role in the development of AMD in animal model. However, there are few clinical evidence. In our present study, we measured the plasma DKK-1(secreted inhibitor of Wnt pathway) levels in AMD patients and investigated if circulating DKK-1 levels are associated with this disease. Our results for the first time showed that decreased circulating levels of DKK-1 are associated with exudative AMD (mainly caused by abnormal blood vessel), and the lower DKK-1 levels in circulation was associated with the higher possibility of having exudative AMD. In addition, our study showed that levels of DKK-1 in circulation have a potential to serve as a novel diagnostic biomarker for exudative AMD.
#328 - 3425. OCT-based angiography of choroidal neovascularization by removing projection artifacts. Qinqin Zhang. May 3, 11am.
To accurately visualize choroidal neovascularization (CNV) and its treatment response, a projection artifact removal (PAR) algorithm was performed on the outer retinal avascular slab (ORAS) of OCT-based angiography (OCTA) images to remove projection artifacts from the top retinal circulations. Optical microangiography (OMAG) as one of the leading techniques of OCTA utilizing the complex OCT signal with a high sensitivity to detect the capillaries was employed in the study. The application of the PAR algorithm on OMAG angiograms can allow for more accurate quantitative evaluation of CNVs before and after treatment and provide comparable or even better images to the current gold standard FA/ICGA. Thus this algorithm may be a useful tool in interpreting images of CNVs that can complement current standard imaging modalities such as FA/ICGA.
#347 - 3719 - D0180. Surgical feasibility of wide-field dual-array suprachoroidal–transretinal stimulation (STS) prosthesis in middle-sized animals. Takeshi Morimoto. May 3, 11am.
Retinal prosthesis is developed to restore the sight of the blind patients with advanced retinitis pigmentosa. We demonstrate that we succeeded in implanting the newly developed dual array electrodes (supra-choroidal transretinal stimulation system) into the eyes in middle sized animals. The blind patients can obtain a double field by our new retinal prosthesis conventionally to improve the bionic vision.
#347 - 3742 - D0203. Clinical trial: subretinal transplantation of CTS hESC derived RPE in the treatment of wet Age-related Macular Degeneration (wAMD). Zheng Qin Yin. May 3, 11am.
Many blinding eye diseases are caused by defects at the interface of light sensing cells (photoreceptors) and cells (Retinal pigment epithelium cells (RPE)) that provide support and nutrition in the back of the eye. Unfortunately, both cell types cannot regrow after damage, therefore currently there is no cure for such diseases. We took a type of immature cells (human embryonic stem cells -- hESCs), which are capable of developing into different cell types, and induced them into RPE cells. After careful safety tests and registered with ClinicalTrials.gov (ChiCTR-OCB-15006423), we injected them into the back of the eyes of three patients with severe blinding diseases, wet Age-related Macular Degeneration (wAMD). Although the primary goal of this clinical trial is to test safety of the treatment, we are pleased to see some improvements of their vision. This work is a proof of concept for using stem cells to treat blinding eye diseases.
#347 - 3741 - D0202. Intravitreal Autologous Bone Marrow Derived Stem Cells in Ischemic Maculopathy Results after 12 Months Follow-up. Felipe Borges. May 3, 11am.
Stem cells (SC) are able to differentiate into specialized cell types as well as to produce molecules that may preserve and stimulate neighbor cells. SC come from two main sources: embryos and bone marrow.
Our study was designed to evaluate whether injection of bone marrow-derived SC into the eye is safe and whether it may improve the vision of persons whose retinal blood vessels have been damaged due to diabetes and other diseases (the retina is inside the eye and is similar to the film in a camera; it produces images for the brain to understand). Examinations included evaluation of vision sharpness (acuity), number of retinal vision cells (photoreceptors), and specific examinations to analyze retinal function, circulation and anatomy.
To date, 16 eyes have been injected with bone marrow-derived SC. The study showed that SC may improve vision sharpness for one month after injection, and after one year the vision was not inferior to vision before SC injection. Anatomical examinations and the number of photoreceptors did not change significantly over the 1-year time period of the study. None of the patients experienced unfavorable effects related to SC injection.
Given the favorable results of this study, the use of bone marrow-derived SC to stimulate vision cells in patients with damaged retinal blood vessels should be studied further. Additional studies may determine the optimal injection frequency to obtain the most benefit from SC therapy for patients with damaged retinal blood vessels.
#362 - 3773. Evaluating choroidal pigmentation in the setting of polypoidal choroidal vasculopathy in a Caucasian population. Talia Kaden. May 3, 3:45pm.
The purpose of this study was to validate the clinical grading of choroidal pigmentation that can be used in clinical practice. Choroidal pigmentation was graded as dark, medium or light. Good intra-and inter observer agreement was observed and there was a good correlation with other objective measures of choroidal pigmentation. Higher rates of dark choroids were observed in Caucasian patients with polypoidal choroidal vasculopathy (PCV) compared to controls. PCV is known to occur more commonly in Asian and African individuals, who have naturally increased choroidal pigmentation. Hence, in Caucasian individuals, a darker choroid may be a risk factor for the development of PCV.
#362 - 3777. Automated identification and quantification of subretinal fibrosis in neovascular age-related macular degeneration using polarization-sensitive optical coherence tomography. Philipp Roberts. May 3, 3:45pm.
Subretinal fibrosis characterizes the end-stage of neovascular age-related macular degeneration (AMD) and is associated with marked visual impairment and irreversible retinal damage. A differentiation between neovascular tissue, which responds well to treatment, and fibrosis, which hardly shows any response to current treatments, is often not possible using conventional optical coherence tomography (OCT), a standard imaging modality for patients with AMD. In this study, participants with subretinal fibrosis secondary to neovascular AMD were examined using a novel imaging modality (polarization-sensitive OCT). Using polarization-sensitive OCT it is possible to distinguish different tissues by their interaction with the polarization of the probing light beam. With this new imaging modality we could successfully and automatically segment fibrous tissue, even in cases with severe distortion of the retinal anatomy.
#361 - 3768. Phase I/II clinical trial of human embryonic stem cell (hESC)-derived retinal pigmented epithelium (RPE) transplantation in Stargardt disease (STGD): One-year result. Manjit Mehat. May 3, 3:45 pm.
Healthy eyesight depends on pigmented cells in the retina to support the function and survival of the overlying light-sensitive cells. Stargardt disease is a genetic disorder of the retina in which the involvement of pigmented cells contributes to impairment of sight. Transplantation of healthy cells to those affected, however, might benefit sight.
We performed a clinical trial to test the safety of transplantation of pigmented retinal cells in individuals with severe impairment of sight owing to advanced Stargardt disease. Pigmented retinal cells were developed and grown in the laboratory from human embryonic stem cells (hESC) prior to transplantation.
We injected a suspension of pigmented retinal cells, in increasing doses, to the retina in one eye of 12 affected adults. As a precaution all participants received immunosuppressive medication to reduce risk of transplant rejection. Areas of new pigmentation in the injected eyes indicated survival of transplanted cells. We identified no serious side effects or any change in sight during the12 month trial.
Transplantation of pigmented retinal cells derived from human embryonic stem cells is well tolerated in the short term. The favourable safety profile supports the prospect of further studies to investigate the potential for benefit in less advanced disease.
#361 - 3769. Transplantation of Autologous induced Pluripotent Stem Cell-Derived Retinal Pigment Epithelium Cell Sheets for Exudative Age Related Macular Degeneration: A Pilot Clinical Study. Yasuo Kurimoto. May 3, 3:45 pm.
Induced pluripotent stem cells (iPS cellCs), which were developed in 2006 by Dr. Shinya Yamanaka for which he was awarded the Nobel Prize, are able to differentiate into any kind all types of body cells and able to self-renew as an unlimitedly unlimited source like embryonic stem cells (ES cellsC). Since iPS cellCs can be generated for each patient directly from adult his/her own cells such as skin cells or blood cells, they do not need without a destruction of embryos like ESCs and can be prepared as an individual patient matched donor source. Presently, iPS cells are regarded as providing the most promising donor source for regenerative medicine.
In September 2014, we conducted the first-in-human iPS cellC-based transplantation therapy successfully. In a patient with advanced exudative age-related macular degeneration (AMD). An iPS cellC-derived retinal pigment epithelium (RPE) sheet, which was had been generated from a small (4 mm in diameter) piece of the patient’s own skin, was transplanted subretinally successfully in the diseased eye after removal of the neovascular membrane. The transplanted RPE sheet survived well without any findings indication of immune rejections nor adverse unexpected proliferation for one and a half years, achieving our primary purpose of this pilot study, i.e., "confirmation of the safety of iPSC-based therapy" and any significant adverse events have not been observed for a year. No additional intraocular injections of anti-vascular endothelial growth factor (VEGF) drug, currently the major treatment for AMD, have been required during this period, and the visual acuity was preserved without additional anti-AMD therapy such as intravitreal injection of anti- vascular endothelial growth factor (VEGF) drug up to now.
#341 - 3588 - B0028. Effect of varying skin surface electrode position on electroretinogram responses recorded using a handheld stimulating and recording system. Angharad Hobby. May 3, 11am.
The retina is the structure at the back of the eye where light is focussed and forms an image, much like film in a camera. When light falls on the retina electrical signals are sent to the brain which allows us to see. However, retinal diseases can alter these signals and reduce the function of the retina causing sight loss. We can image the retina through specialised equipment in eye clinics, however there is sometimes no visible sign of disease.
Our research assesses the electrical signals that the retina produces, and how these can tell us about how well the retina is functioning. We are also testing new ways that patients may be able to have these recordings taken and how changing the recording techniques can alter the quality of results. Our study has discovered that changing the recording technique alters the quality of some results but not others. This may be useful for some patients who need assessment of their retinal disease or the treatments used to combat it.
Visual Psychophysics/Physiological Optics
#366 - 3803. Stereoscopic acuity as a function of induced monocular defocus measured with an adaptive optics simulator. Silvestre Manzanera. May 3, 3:45pm.
Depth perception is the visual ability to distinguish which objects in a scene are closer or further to us. Because of the separation between our eyes, the image that each of them produces is slightly different due to the different perspective but we only perceive one image because our brain fuses both images and extracts the information about depth at the same time. It is well known that if the sharpness of both images is very different depth perception is compromised. The different quality in both images could happen in some pathologies or as a side effect when applying certain techniques to correct the loss of ability of the older eye to focus on near objects (presbyopia). The novelty of our research is that we have quantified the degradation of depth perception as a function of the degree of different sharpness of the images on each eye. This could be used in the clinical practice as a guide to know how the prescription of this technique to correct presbyopia might affect the patient’s perception in depth.