Background: Dyop® is a dynamic optotype with a rotating and segmented visual stimulus. It can be used for visual acuity and refractive error measurement. The objective of the study was to compare refractive errormeasurement using the Dyop® acuity and LogMAR E charts.
Methods: Fifty subjects aged 18 or above with aided visual acuity better than 6/12 were recruited. Refractive error was measured by subjective refraction methods using the Dyop® acuity chart and LogMAR E charts and the duration of measurement compared. Thibo’s notation was used to represent the refractive error obtained for analysis.
Results: There was no significant difference in terms of spherical equivalent (M) (P=0.96) or J0 (P=0.78) and J45 (P=0.51) components measured using the Dyop® acuity and LogMAR E charts. However, subjective refraction measurement was significantly faster using the Dyop® acuity chart (t=4.46, P<0.05), with an average measurement time of 419.90±91.17 versus 452.04±74.71 seconds using the LogMAR E chart.
Conclusions: Accuracy of refractive error measurement using a Dyop® chart was comparable with use of a LogMAR E chart. The dynamic optotype Dyop® could be considered as an alternative fixation target to be used in subjective refraction.
Abstract: Submacular haemorrhage (SMH) is a sight threatening complication that can occur in exudative age related macular degeneration (AMD), but has been described to occur more frequently in eyes with polypoidal choroidal vasculopathy (PCV). Left untreated, SMH carries a grave visual prognosis. Thus, expedient diagnosis and effective management of this complication is of paramount importance. The treatment strategies for SMH include (I) displacement of blood from the fovea, usually by injection of an expansile gas; (II) pharmacologic clot lysis such as with recombinant tissue plasminogen activator (rtPA); and (III) treatment of the underlying choroidal neovascularization (CNV) or PCV, such as with anti-vascular endothelial growth factor (anti-VEGF) agents. These three strategies have been employed in isolation or in combination, some concurrently and others in stages. rtPA has demonstrable effect on the liquefaction of submacular clots but there are remaining uncertainties with regards to the dose, safety and the timing of initial and repeat treatments. Potential side effects of rtPA include retinal pigment epithelial toxicity, increased risk of breakthrough vitreous haemorrhage and systemic toxicity. In cases presenting early, pneumatic displacement alone with anti-VEGF may be sufficient. Anti-VEGF monotherapy is a viable treatment option particularly in patients with thinner SMH and those who are unable to posture post pneumatic displacement.
Background: The ex vivo model represented by mouse retinal explants in culture is a useful experimental model to investigate the molecular mechanism involved in neurovascular diseases such as diabetic retinopathy (DR). It ensures an experimental overview with more complete respect to isolate cells and reduce problems in terms of accessibility and management with respect to in vivo model. In particular, it allows the evaluation of the relationship between retinal cells in response to the typical stressors involved in DR pathogenesis.
Methods: Ex vivo retinal fragments derived from 3- to 5-week-old C57BL/6J mice. In particular, after dissection, the retina is cut into 4 separate fragments and transferred onto inserts placed with ganglion cells up. Once in culture, the explants could be treated in stress conditions typical of DR. In particular, this study protocol describes the procedure for the preparation and the culture of retinal explants with specific metabolic stressors such as high glucose (HG), advanced glycation end product (AGE), and oxidative stress (OS). In the end, this paper provides the protocols to perform molecular analyses in order to evaluate the response of retinal explants to stress and/or neuroprotective treatments.
Discussion: The cultured retinal explants represent an ex vivo experimental model to investigate the molecular mechanisms involved in neurovascular diseases such as DR. Moreover, they could be useful to test the effect of neuroprotective compounds in response to metabolic stressors in a fewer time respect to an in vivo model. In conclusion, retinal explants in culture represent a valuable experimental model to conduct further studies to better understand the pathophysiology of DR.
Background: Retinal degeneration is a common feature of several retinal diseases, such as retinitis pigmentosa and age-related macular degeneration (AMD). In this respect, experimental models of photo-oxidative damage reproduce faithfully photoreceptor loss and many pathophysiological events involved in the activation of retinal cell degeneration. Therefore, such models represent a useful tool to study the mechanisms related to cell death. Their advantage consists in the possibility of modulating the severity of damage according to the needs of the experimenter. Indeed, bright light exposure could be regulated in both time and intensity to trigger a burst of apoptosis in photoreceptors, allowing the study of degenerative mechanisms in a controlled fashion, compared to the progressive and slower rate of death in other genetic models of photoreceptor degeneration.
Methods: Here, an exemplificative protocol of bright light exposure in albino rat is described, as well as the main outcomes in retinal function, photoreceptor death, oxidative stress, and inflammation, which characterize this model and reproduce the main features of retinal degeneration diseases.
Discussion: Models of photo-oxidative damage represent a useful tool to study the mechanisms responsible for photoreceptor degeneration. In this respect, it is important to adapt the exposure paradigm to the experimental needs, and the wide range of variables and limitations influencing the final outcomes should be considered to achieve proper results.
Trial Registration: None.
Background: Retinopathy of prematurity (ROP) is considered as the most common reason for blindness in children, particularly in preterm infants. The disease is characterized by the dysregulation of angiogenic mechanisms due to preterm birth, leading ultimately to vascular abnormalities and pathological neovascularization (NV). Retinal detachment and vision loss could represent a concrete risk connected to the most severe forms of ROP, also characterized by inflammation and retinal cell death.
Methods: During the last decades, many animal models of oxygen-induced retinopathy (OIR) have been recognized as useful tools to study the mechanisms of disease, since they reproduce the hallmarks typical of human ROP. Indeed, modulation of retinal vascular development by exposure to different oxygen protocols is possible in these animals, reproducing the main pathological phenotypes of the disease. The easy quantification of abnormal NV and the possibility to perform electrophysiologic, histological and molecular analyses on these models, make OIR animals a fundamental instrument in studying the pathophysiology of ROP and the effects of novel treatments against the disease.
Discussion: Here, the most commonly used OIR protocols in rodents, such as mice and rats, are described as well as the main pathological outcomes typical of these models. Despite their limitations and variables which should be considered whilst using these models, OIR models display several characteristics which have also been confirmed in human patients, validating the usefulness of such animals in the pre-clinical research of ROP.
Background: Spontaneously resolved primary congenital glaucoma is rare and the mechanism remains unknown. Previous literature described the phenomenon of spontaneous resolution of primary congenital glaucoma, with no further reports on follow-up visits and visual development of patients. We report a case of unilateral spontaneously resolved primary congenital glaucoma at a 7-year follow-up visit and describe the differential development of axial length (AL) between affected eye and healthy eye.
Case Description: A 6-year-old boy firstly presented at Zhongshan Ophthalmic Center with expanded corneas and ruptures in Descemet’s membranes (Haab’s striae) and apparently thin retinal nerve fiber layer (RNFL) in the left eye (LE), but normal intraocular pressure (IOP) of both eyes without anti-glaucoma medications or surgeries. At 7-year follow-up, the IOPs of bilateral eyes were stable ranging from 8 to 11 mmHg. A cup to disc ratio and the RNFL was stable in the LE at the following visit. The AL increased almost 3 mm in the right eye (RE) but 1.5 mm in the LE. Without anti-glaucoma medications or surgeries, the primary congenital glaucoma was spontaneously resolved.
Conclusions: It may figure out the development and influence of the affected eye of the patient, including AL and refraction state with regular ophthalmic examination at periodic follow-up.
Background: Axonal degeneration caused by damage to the optic nerve can result in a gradual death of retinal ganglion cells (RGC), leading to irreversible vision loss. An example of such diseases in humans includes optic nerve degeneration in glaucoma. Glaucoma is characterized by the progressive degeneration of the optic nerve and the loss of RGCs that can lead to loss of vision. The different animal models developed to mimic glaucomatous neurodegeneration, all result in RGC loss consequent optic nerve damage.
Methods: The present article summarizes experimental procedures and analytical methodologies related to one experimental model of glaucoma induced by optic nerve crush (ONC). Point-by-point protocol is reported with a particular focus on the critical point for the realization of the model. Moreover, information on the electroretinogram procedure and the immunohistochemical detection of RGCs are described to evaluate the morpho-functional consequences of ONC.
Discussion: Although the model of ONC is improperly assimilated to glaucoma, then the ONC model simulates most of the signaling responses consequent to RGC apoptosis as observed in models of experimental glaucoma. In this respect, the ONC model may be essential to elucidate the cellular and molecular mechanisms of glaucomatous diseases and may help to develop novel neuroprotective therapies.
