Prem S. Subramanian

Progression of asymptomatic optic disc swelling to non-arteritic anterior ischaemic optic neuropathy

Background The time of onset of optic disc swelling in non-arteritic anterior ischaemic optic neuropathy (NAION) is not known, and it is commonly assumed to arise simultaneously with vision loss. Our goal is to report the presence and persistence of optic disc swelling without initial vision loss and its subsequent evolution to typical, symptomatic NAION. Methods Clinical case series of patients with optic disc swelling and normal visual acuity and visual fields at initial presentation who progressed to have vision loss typical of NAION. All subjects underwent automated perimetry, disc photography and optic coherence tomography and/or fluorescein angiography to evaluate optic nerve function and perfusion. Results Four patients were found to have sectoral or diffuse optic disc swelling without visual acuity or visual field loss; the fellow eye of all four had either current or prior NAION or a ‘disc at risk’ configuration. Over several weeks of clinical surveillance, each patient experienced sudden onset of visual field and/or visual acuity loss typical for NAION. Conclusions Current treatment options for NAION once vision loss occurs are limited and may not alter the natural history of the disorder. Subjects with NAION may have disc swelling for 2–10 weeks prior to the occurrence of visual loss, and with the development of new therapeutic agents, treatment at the time of observed disc swelling could prevent vision loss from NAION.

Risk of fall (RoF) intervention by affecting visual egocenter through gait analysis and yoked prisms

BACKGROUND Following a neurologic event such as traumatic brain injury (TBI), cerebrovascular accident (CVA), and chronic neurological conditions including Parkinsons disease, multiple sclerosis, and cerebral palsy a shift in the visual midline (egocenter) can directly affect posture, balance and spatial orientation. As a consequence, this increases the risk of fall (RoF) and injury that imposes a major financial burden on the public health system. OBJECTIVE To determine if there is a statistically significant change in balance with the intervention of yoked prisms to reduce the risk of fall in subjects with neurological impairments. METHODS Ambulation of thirty-six subjects was evaluated on a pressure sensitive mat before and after intervention with yoked prisms. Changes in gait and balance were analyzed in the anterior-posterior (AP) and medial-lateral (ML) axes during ambulation. RESULTS T-tests for each measure comparing the difference-of-differences to a zero change at baseline returned statistically significant reductions in both AP (p <  0.0001; 95% CI: 1.368- 2.976) and ML (p = 0.0002; 95% CI: 1.472- 4.173) imbalances using specifically directed yoked prisms to correct the visual midline deviation. CONCLUSION These findings demonstrate that yoked prisms have the potential to provide a cost-effective means to restore the visual midline thereby improving balance, reduce RoF and subsequent injury.

Optical Coherence Tomography Angiography in Optic Disc Swelling

PURPOSE To compare optical coherence tomography angiography (OCT-A) of peripapillary total vasculature and capillaries in patients with optic disc swelling. DESIGN Cross-sectional study. METHODS Twenty nine eyes with acute nonarteritic anterior ischemic optic neuropathy (NAION), 44 eyes with papilledema, 8 eyes with acute optic neuritis, and 48 eyes of normal subjects were imaged using OCT-A. Peripapillary total vasculature information was recorded using a commercial vessel density map. Customized image analysis with major vessel removal was also used to measure whole-image capillary density and peripapillary capillary density (PCD). RESULTS Mixed models showed that the peripapillary total vasculature density values were significantly lower in NAION eyes, followed by papilledema eyes and control eyes, using commercial software (P < .0001 for all comparisons). The customized software also showed significantly lower PCD of NAION eyes compared with papilledema eyes (all P < .001), but did not show significant differences between papilledema and control subjects. Our software showed significantly lower whole image and PCD in eyes with optic neuritis than papilledema. There was no significant difference between NAION and optic neuritis using our software. The area under the receiver operating curves for discriminating NAION from papilledema eyes and optic neuritis from papilledema eyes was highest for whole-image capillary density (0.94 and 0.80, respectively) with our software, followed by peripapillary total vasculature (0.9 and 0.74, respectively) with commercial software. CONCLUSIONS OCT-A is helpful to distinguish NAION and papillitis from papilledema. Whole-image capillary density had the greatest diagnostic accuracy for differentiating disc swelling.

Homonymous Hemianopia and Vision Restoration Therapy

Homonymous hemianopia from stroke causes visual disability. Although some patients experience spontaneous improvement, others have limited to no change and may be left with a severe disability. Current rehabilitation strategies are compensatory and cannot restore function. Animal studies suggest that central nervous system plasticity could allow for redirection of lost visual function into undamaged areas of cortex. A commercial therapy system was developed, from which claims of visual field expansion were disputed by independent researchers. The treatment remains controversial with seemingly contradictory data being generated. Continued research is underway to demonstrate the (non-)efficacy of this treatment method.

Early Macular Vessel Density Loss in Acute Ischemic Optic Neuropathy Compared to Papilledema: Implications for Pathogenesis

Purpose This study compares macular and parafoveal vasculature in patients with optic disc swelling. Methods Twenty eyes with acute nonarteritic anterior ischemic optic neuropathy (NAION), 39 eyes with papilledema at first presentation, and 22 eyes of normal subjects were imaged using optical coherence tomography angiography (OCT-A). Macular ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer thicknesses were measured in addition to macula and parafovea superficial and deep vasculature. Results Age- and gender-mixed models showed that the macular and parafoveal superficial and deep vasculature density values were significantly lower in NAION eyes than control eyes (P ≤ 0.0001 for all comparisons). All vessel density values were not statistically different between papilledema eyes and control eyes. Whole superficial and deep macula vasculature in the NAION eyes (45.9% ± 4.2%, 50.9% ± 6.5%) were significantly lower than in papilledema eyes (50.5% ± 4.6%, 57.3% ± 6.1%) (P = 0.03 and P = 0.01, respectively). No significant differences in GCC thickness were observed among NAION, papilledema, and control eyes. Whole superficial and deep macular vasculatures, but not macular GCC thickness, were significantly correlated with visual field mean deviation (r = 0.39, P = 0.001 and r = 0.41, P < 0.001, respectively). Conclusions Macular OCT-A is able to show early macular vasculature abnormalities associated with optic nerve damage; this change occurs before detectable macular GCC atrophy. Translational Relevance Macular vessel density measurement offers an opportunity to evaluate the optic nerve damage at initial presentation, but further longitudinal studies are needed.

Practical Management of Pediatric Ocular Disorders and Strabismus: a case-based approach. Eds. Elias I Traboulsi, Virginia Miraldi Utz (2017) ISBN 978-1-4939-2744-9 Springer

The editors of this well-illustrated and written textbook very clearly state in their Preface that their goal in producing this textbook was not to attempt to be all-encompassing, but to provide a more focused and directed approach to the topics of each chapter. Overall, the chapters are arrayed in a traditional manner, with an initial chapter dedicated to the examination of the pediatric patient, while subsequent chapters are arrayed in anatomic fashion from the front to the back of the eye. There is extensive coverage of both common and uncommon disorders, which should be of great benefit to trainees as well as comprehensive ophthalmologists who may encounter patients with these conditions very infrequently. The editors also have chosen expert authors who can share not only a comprehensive review of available evidence and literature but also their personal tips and experience to guide the reader in the practical aspects of the material. This does not mean that the common subjects are given short shrift. The section on examination techniques and basic management of refractive errors and amblyopia is richly illustrated with practical photos and diagrams of how and when to perform diagnostic tests such as measurement of accommodation and AC-to-A ratios. These fundamental methods are covered in other texts but not in the step-by-step manner shown here with sidebar case examples to reinforce the concepts. As a neuro-ophthalmologist who alsomanages adult strabismus, I found these chapters to be an outstanding review of some methods and conditions that I employ and see less commonly in my clinical practice. A number of chapters and chapter sections demonstrate the use of new diagnostic imaging technologies such as wide-field fundus photography and angiography and ocular coherence tomography (OCT) and how to use them in children. A major challenge in using these techniques in children is in the simple act of capturing the images before the child moves, loses interest, or decides not to cooperate. The authors again give practical advice based on their own knowledge, and such information alone would justify obtaining this textbook as a guide. These chapters also provide a number of useful illustrations with case examples that help the reader to understand the interpretation of the images and also to recognize some pitfalls and common errors. For example, OCT in a patient with optic atrophy and papilledema that leads to a falsely normal-appearing retinal nerve fiber layer is shown with corresponding neuroimaging of obstructive hydrocephalus. Finally, although some chapters are less Bcase-based^ than others, they all provide some useful case illustrations and diagnostic flowcharts that will guide the less familiar reader who is confronted with a pediatric patient who has, for example, suspected glaucoma or new onset nystagmus. The chapter authors wisely do not spend much time writing about very specific treatment options or techniques for particular diseases, recognizing such information rapidly becomes outdated and even incorrect. There are, however, a number of very practical Appendices including a description of strabismus surgery instruments and a guide to IOL power calculations. In his Foreword, Dr. Gene Helveston wisely comments that textbooks must provide value beyondwhat can be searched on the Internet, and I think this book has achieved its goal of providing a practical guide written by expert authors in a style accessible to residents, fellows, and comprehensive ophthalmologists. I suspect pediatric ophthalmologists also would benefit from the tips and descriptions regarding patients with less common and/or more challenging disorders. * Prem S. Subramanian prem.subramanian@ucdenver.edu

Neuro-ophthalmolmic Sequelae of Sustained Microgravity

Space travel has presented novel challenges both technologically and physiologically to the human passenger. Since the first manned spaceflight in 1961, the impact of atmospheric changes and a microgravity environment on the human body have been carefully studied and characterized. The Jules Verne novel “From the Earth to the Moon” published in 1865, nearly 100 years before the first manned mission, raised questions and theories about the weightlessness which would be experienced in space. As terrestrial beings who have evolved in earth’s gravity, the environment of weightlessness induces remarkable multisystem changes which affect the astronauts who venture into space. These changes cover a wide spectrum ranging from transient sensory imbalances and nausea to profound hemodynamic and metabolic alterations, to more chronic anemia, weakening of bones, muscles, and the immune system. Additionally, dramatic and unique ophthalmologic changes are experienced in varying degrees after time spent in a microgravity environment. Findings have included optic disk edema, choroidal folds and cotton wool spots, hyperopic refractive shifts after prolonged spaceflight, and globe flattening with increased CSF signal in the optic nerve sheaths. The retrospective observational report by Mader et al. in 2011 described these findings in a cohort of seven astronauts who had visited the International Space Station (ISS) for a period of 6 months, as well as reviewed and correlated the results of 300 postflight surveys regarding in-flight vision changes. The US National Aeronautics and Space Administration’s (NASA) Space Medicine Division has also evaluated and documented these changes through clinical exam, OCT, MRI, and ultrasound testing of astronauts. As will be discussed, many features of this phenomenon are ophthalmoscopically similar to terrestrial increased intracranial pressure (ICP), and elevated ICP is thought to play at least a partial role. In 2011, NASA held a visual impairment intracranial pressure (VIIP) summit to discuss this problem, and this conference raised significant concerns about longer missions or even visitation to planets with greatly reduced gravity, such as Mars. The pathogenesis of these findings is incompletely understood due to limitations of monitoring and testing during spaceflight. The purpose of this discussion is to review the pathology and discuss possible mechanisms, most importantly the phenomenon of cephalad fluid shifts in a microgravity environment, and to consider possible approaches to investigating adaptive responses. Further research in this area presents practical challenges, such as finding a suitable ground-based research model and/or monitoring ICP during spaceflight, but is necessary to both characterize the physiology as well as to ultimately provide countermeasures for future long-duration space missions.

Industrial and Military Eye Injuries and Eye Protection Challenges

Eye injuries are prevalent in environments with high-velocity particle motion and/or high temperatures, and injuries range from periocular contusions and burns to corneoscleral lacerations and frank globe ruptures. Although they often are available, protective devices may be unused and/or not mandated. Such environments include heavy industrial settings such as metalworking and welding, in which workers are exposed to threats from sometimes red-hot and fast-moving metal shards, although these risks can be reduced with mandatory safety regimens. Many sports, including lacrosse, baseball, squash, and ice hockey – activities that particularly center around relatively small and hard balls and pucks moving at high speeds – also feature high eye injury rates, usually in the absence (baseball, squash) or inefficacy (ice hockey, lacrosse) of safety equipment.

Neuro-ophthalmic manifestations of cerebrovascular accidents

Purpose of review Ocular functions can be affected in almost any type of cerebrovascular accident (CVA) creating a burden on the patient and family and limiting functionality. The present review summarizes the different ocular outcomes after stroke, divided into three categories: vision, ocular motility, and visual perception. We also discuss interventions that have been proposed to help restore vision and perception after CVA. Recent findings Interventions that might help expand or compensate for visual field loss and visuospatial neglect include explorative saccade training, prisms, visual restoration therapy (VRT), and transcranial direct current stimulation (tDCS). VRT makes use of neuroplasticity, which has shown efficacy in animal models but remains controversial in human studies. Summary CVAs can lead to decreased visual acuity, visual field loss, ocular motility abnormalities, and visuospatial perception deficits. Although ocular motility problems can be corrected with surgery, vision, and perception deficits are more difficult to overcome. Interventions to restore or compensate for visual field deficits are controversial despite theoretical underpinnings, animal model evidence, and case reports of their efficacies.

A case of non-arteritic anterior ischemic optic neuropathy after completion of Harvoni therapy

Purpose To report the first reported case of non-arteritic anterior ischemic optic neuropathy (NAION) associated with the use of Harvoni (Gilead Sciences, Foster City, CA, USA), a newly approved treatment for Hepatitis C. Observations We report a case of NAION in a hepatitis C patient who completed Harvoni therapy just prior to presentation. Harvoni was suspected to be the causative agent given a lack of NAION risk factors in an otherwise healthy young patient. Conclusions and importance NAION is an acute, painless vision loss that typically affects adults over 50. The mechanism of NAION remains uncertain although numerous associations have been identified including certain medications. Harvoni, a combination drug of ledipasvir/sofosbuvir, is a recently FDA-approved treatment for Hepatitis C. To date, however, no ophthalmological side effects have been reported with its use. Continued surveillance of patients treated with Harvoni will be needed to determine if additional events are observed in the future.