Background: Visual deficits, caused by ocular disease or trauma to the visual system, can cause lasting damage with insufficient treatment options available. However, recent research has focused on neural plasticity as a means to regain visual abilities. In order to better understand the involvement of neural plasticity and reorganization in partial vision restoration, we aim to evaluate the partial recovery of a visual deficit over time using three behavioural tests. In our study, a partial optic nerve crush (ONC) serves as an induced visual deficit, allowing for residual vision from surviving cells.
Methods: Three behavioural tests—optokinetic reflex, object recognition, and visual cliff—were conducted in 9 mice prior to a bilateral, partial ONC, then 1, 3, 7, 14, 21, and 28 days after the ONC. The optokinetic reflex test measured the tracking reflex in response to moving sinusoidal gratings. These gratings increase in spatial frequency until a reflex is no longer observed, i.e., a visual acuity threshold is reached. The object recognition test examines the animal’s exploratory behaviour in its capacity to distinguish high versus low contrast objects. The visual cliff test also evaluates exploratory behaviour, by simulating a cliff to observe the animal’s sense of depth perception. All three tests provide an estimate of the rodent’s visual abilities at different levels of the visual pathway.
Results: The partial optic nerve crush resulted in a total loss of visual acuity as measured by the optokinetic reflex. The deficit did not show improvement during the 4 following weeks. Despite the visual cliff test showing a non-significant decrease in deep end preference 1-day post ONC, though this was not the case for subsequent test occasions. The object recognition test showed no significant trends.
Conclusions: In conclusion, the optokinetic reflex test showed a significant loss of function following the visual deficit, but no recovery. However, a complimentary pilot study shows visual recovery using lighter crush intensities. The spatial visual function does not seem to be affected by the ONC, suggesting that the object recognition and visual cliff tests, in their current design, may rely on somatosensory means of exploration.
Background: The aim of this project is to develop a new standardized and cost-efficient method to compare optical coherence tomography (OCT) scans to their corresponding paraffin embedded histopathology sections in post-mortem eyes. This correlation will clarify the interpretation of OCT images, and it will also enable direct immunohistochemical characterization of features observed on OCT.
Methods: Study design: donor eyes were obtained from two separate eye banks. In order to minimize post-mortem change like retinal detachment and vitreous opacification, the eyes were fixed in a previously tested fixative solution. Time between death and fixation has been kept under 6 hours. Methods: Using a customized imaging device, nine post-mortem eyes were imaged with a SD-OCT machine. Subsequently, an 8mm trephine was used to isolate a portion of the posterior pole including the macular area and the optic nerve head for histopathological analysis. Paraffin embedded cross sections of the retina were obtained and visually compared to each OCT image (b-scans).
Results: To facilitate the correlation of OCT images to their histopathological sections, three principle aspects were controlled during tissue processing: rotation, tilt and location. Using markings as well as anatomical landmarks, serial histopathological sections in an orientation comparable to OCT b-scans were obtained, thereby facilitating image pairing.
Conclusions: Compared to other well-established methods using resin and electron microscopy, our standardized Methods allowed us to successfully compare OCT b-scans to serial retinal cross sections of a wider macular area at a lower cost. Our novel approach allows us to translate features observed on OCT images into well-established histopathological images, providing the clinician with additional tools to obtain difficult diagnoses with more confidence.
Abstract: Pediatric neuro-ophthalmology is a subspecialty within neuro-ophthalmology. Pediatric neuro-ophthalmic diseases must be considered separate from their adult counterparts, due to the distinctive nature of the examination, clinical presentations, and management choices. This manuscript will highlight four common pediatric neuro-ophthalmic disorders by describing common clinical presentations, recommended management, and highlighting recent developments. Diseases discussed include pediatric idiopathic intracranial hypertension (IIH), pseudopapilledema, optic neuritis (ON) and optic pathway gliomas (OPG). The demographics, diagnosis and management of common pediatric neuro-ophthalmic disease require a working knowledge of the current research presented herein. Special attention should be placed on the differences between pediatric and adult entities such that children can be appropriately diagnosed and treated.
Abstract: Pathologic myopia is the major cause of the loss of the best-corrected visual acuity (BCVA) worldwide, especially in East Asian countries. The loss of BCVA is caused by the development of myopic macula patchy, myopic traction macula patchy, and myopic optic neuropathy (or glaucoma). The development of such vision-threatening complications is caused by eye deformity, characterized by a formation of posterior staphyloma. The recent advance in ocular imaging has greatly facilitated the clarification of pathologies and pathogenesis of pathological myopia and myopia-related complications. These technologies include ultra-wide field fundus imaging, swept-source optical coherence tomography, and 3D MRI. In addition, the new treatments such as anti-VEGF therapies for myopic choroid all neovascularization have improved the outcome of the patients. Swept-source OCT showed that some of the lesions of myopic maculopathy were not simply chorioretinal atrophy but were Bruch’s membrane holes. Features of myopic traction maculopathy have been analyzed extensively by using OCT. The understanding the pathophysiology of complications of pathologic myopia is considered useful for better management of this blinding eye disease.
Abstract: The biological mechanisms of eye growth and refractive development are increasingly well characterised, a result of many careful studies that have been carried out over many years. As the outer coat of the eye, the sclera has the ultimate impact on the restraint or facilitation of eye growth, thus any changes in its biochemistry, ultrastructure, gross morphology and/or biomechanical properties are critical in refractive error development and, in particular, the development of myopia. The current review briefly revisits our basic understanding of the structure and biomechanics of the sclera and how these are regulated and modified during eye growth and myopia development. The review then applies this knowledge in considering recent advances in our understanding of how the mechanisms of scleral remodelling may be manipulated or controlled, in order to constrain eye growth and limit the development of myopia, in particular the higher degrees of myopia that lead to vision loss and blindness. In doing so, the review specifically considers recent approaches to the strengthening of the sclera, through collagen cross-linking, scleral transplantation, implantation or injection of biomaterials, or the direct therapeutic targeting and manipulation of the biochemical mechanisms known to be involved in myopia development. These latest approaches to the control of scleral changes in myopia are, where possible, placed in the context of our understanding of scleral biology, in order to bring a more complete understanding of current and future therapeutic interventions in myopia, and their consequences.
Background: To investigate the microstructural features of parapapillary gamma zone and beta zone and their relationship with three-dimensional optic disc shape in non-myopic eyes.
Methods: This cross-sectional study included 62 non-myopic eyes with parapapillary gamma or beta zone and 70 control eyes. On the spectral domain optical coherent tomography (SD-OCT) images, we measured the area of gamma zone and beta zone, the length of border tissue, and related disc parameters. The disc ovality index, disc rotation degrees around three axes, Bruch’s membrane opening (BMO) ovality ratio were calculated based on the SD-OCT images.
Results: The parapapillary gamma zone composed by externally oblique border tissue was found in inferior, nasal and temporal quadrants of the non-myopic eyes. The presence of gamma zone in non-myopic eyes was correlated with smaller disc ovality index, larger rotation degree around vertical and horizontal axes, and larger BMO ovality ratio (P<0.001). Compared with the non-temporal gamma zone group, eyes with temporal gamma zone had a longer axial length and rotated more around vertical axes (P<0.001). Multivariate analysis showed that the area of gamma zone was correlated with the disc ovality index (P<0.001). The presence and area of beta zone was correlated with age (P<0.01).
Conclusions: In non-myopic eyes, the parapapillary gamma zone composed by external oblique border tissue was significantly associated with the disc ovality and disc rotations around vertical and horizontal axes. From a biomechanical perspective, parapapillary gamma zone may contribute to the optic disc stability in association with the structure of BMO.
Abstract: Acute retinal necrosis (ARN) is a devastating syndrome characterized by panuveitis, retinal necrosis, and a high rate of retinal detachment that may result in poor visual outcomes if not promptly diagnosed and treated. ARN is most commonly caused by viruses within the herpesvirus family. Etiologies include varicella-zoster virus, herpes simplex virus, and cytomegalovirus, and may be promptly diagnosed by polymerase chain reaction testing of aqueous or vitreous fluid. The true incidence of ARN is not known due to its rarity; as a result, clinical treatment is often guided by retrospective case series, case reports, and expert opinion. Standard of care has evolved over time but currently includes a combination of systemic and intravitreal antiviral in conjunction with topical or oral steroids and surgical therapy as needed. Combination therapy may reduce the rate of severe vision loss and increase the rate of visual acuity gain, although further studies are needed in this area. In particular for patients with mild to moderate disease, combination therapy may reduce the rate of retinal detachment. Adjunctive therapies including oral corticosteroid and prophylactic laser barricade are incompletely studied, but corticosteroid in particular, may reduce inflammation, which also is involved in the severe disease pathogenesis observed in ARN. This review discusses the advances in diagnosis and treatment of ARN, including management with combination antiviral medication and surgical interventions.
