Background: In recent years posterior corneal astigmatism and its effect on total corneal astigmatism has been studied, with research showing that this can impact total astigmatism. This study aims to ascertain if there is significant change in the posterior corneal astigmatism after cataract surgery and its impact on the total astigmatism.
Methods: Analysis of 76 eyes that underwent cataract surgery with monofocal intraocular lens implantation. Corneal topography was performed with Pentacam (OCULUS?) pre- and post-operatively. Total corneal astigmatism was calculated with the algorithm of vergence tracing. We compared preoperative and postoperative changes in the magnitude and axis differences of anterior corneal curvature astigmatism, posterior corneal curvature astigmatism and the calculated total corneal astigmatism. We calculated the correlation between the total preoperative astigmatism and the difference between total corneal astigmatism and anterior corneal astigmatism.
Results: The mean preoperative and postoperative posterior astigmatism was 0.31±0.02 D, showing no significant differences before and after surgery (P=0.989). Statistically significant differences between the calculated total corneal astigmatism and anterior corneal astigmatism were registered preoperatively and postoperatively in the with-the-rule anterior (WTR) corneal astigmatism (P=0.004, P<0.0001); against-the-rule (ATR) anterior corneal astigmatism (P<0.0001, P<0.0001) and in the oblique (P=0.026, P=0.019) subgroups. The posterior corneal astigmatism and the total corneal astigmatism correlated positively with the differences between the total corneal and anterior corneal astigmatism (R=0.378, P=0.001).
Conclusions: There were statistically significant differences between the magnitude of the total astigmatism and anterior corneal astigmatism, underlining the impact of posterior corneal astigmatism. A positive correlation between the preoperative posterior astigmatism and the difference between the total corneal and the anterior corneal astigmatism suggests a specially relevant role of posterior corneal astigmatism when evaluating patients with higher degrees of astigmatism.
Abstract: Myopia in children remains a major public health problem worldwide, especially in some Asian countries such as China, Singapore and Japan. Although many interventions have been attempted, few has been proven to be effective in controlling onset and progression of myopia in children. Environmental factors, genetic susceptibility or ethnic differences can affect the efficacy of these interventions. However, many questions remain unclear and even controversial for controlling myopia. China has the biggest population with myopia, especially for children myopia. Thus, it is of importance to present what achievements Chinese scientists have made in the field of myopia control in children. We summarize the current findings on myopia control in children from the Anyang Childhood Eye Study, including epidemiological data, clinical trials, systematic reviews and meta-analyses, and compare them with studies in other countries to find potential clues for controlling myopia in children.
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: Decrease of ocular blood flow has been linked to the pathogenesis of ocular diseases such as glaucoma and age-related macular degeneration. Current methods that measure the pulsatile blood flow have major limitations, including the assumption that ocular rigidity is the same in all eyes. Our group has recently developed a new method to measure the pulsatile choroidal volume change by direct visualization of the choroid with OCT imaging and automated segmentation. Our goal in this study is to describe the distribution of PCBF in a healthy Caucasian population.
Methods: Fifty-one subjects were recruited from the Maisonneuve-Rosemont Hospital Ophthalmology Clinic and underwent PCBF measurement in one eye. The distribution of PCBF in healthy eyes was assessed.
Results: The distribution of PCBF among the healthy eyes was found to be 3.94±1.70 μL with this technique.
Conclusions: This study demonstrates the normal range of PCBF values obtained in a healthy Caucasian population. This technique could be used for further investigation of choroid pulsatility and to study glaucoma pathophysiology.
Abstract: Cornea serves as the partial front barrier and major light reflection organ of the eye. The integrity of corneal surface is essential for ocular function. Injuries or congenital diseases could significantly destruct the homeostasis of the ocular surface, especially the microenvironment of limbal epithelial stem cells (LESCs), and will eventually cause dysfunction of corneal regeneration and diminish of LESCs. The loss of LESCs by different reasons are named limbal stem cell deficiency (LSCD), which is one of the leading cause of vision loss worldwide. To restore the corneal surface, LESC transplantation in the form of tissue or cell cultures is currently a viable and promising method to treat LSCD. In this review, we aim to introduce the characters and niche of LESCs, and discuss different aspects of its application in cornea surface reconstruction.
Background: To measure the anterior and posterior segment structural features of acute primary angle-closure (APAC) eyes.
Methods: A total of 36 subjects with unilateral APAC were recruited in this study. The ocular biometric characteristics were measured by anterior segment optical coherence tomography (AS-OCT) and swept source optical coherence tomography (SS-OCT), respectively at baseline, 2 weeks, and 1 month after surgical intervention.
Results: At baseline, when compared with the fellow eyes, APAC-affected eyes showed significantly greater corneal thickness (P=0.004), shallower anterior chamber depth (ACD) (P<0.001), smaller anterior chamber area (ACA) (P=0.013), angle opening distance at 750 μm from the scleral spur (AOD750) (P=0.002), trabecular–iris space area at 750 μm from the scleral spur (TISA750) (P=0.033), angle recess area (ARA) (P=0.014), and iris area (IARE) (P=0.003), less iris curvature (ICURVE) (P=0.003), and larger lens vault (LV) (P=0.030). After intervention, the corneal thickness was significantly decreased at 1 month (P<0.001), while ACD, ACA, and AOD750 were significantly increased at 2 weeks and 1 month (all P<0.017). Changes in ACD were correlated with decreasing LV (P<0.05). The posterior segment parameters did not change over the 4-week period.
Conclusions: When compared with the fellow eyes, APAC-affected eyes had greater corneal thickness, shallower anterior chamber, narrower angle, less ICURVE, and larger LV. After intervention, the corneal thickness was decreased, while the shallower anterior chamber was relieved to some extent.
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.
