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: This submission will briefly review the anatomy and physiology of the optic nerve, and highlight various ischemic optic neuropathies including anterior ischemic optic neuropathies (non-arteritis and arteritic), diabetic papillopathy, posterior ischemic optic neuropathies, and ischemic optic neuropathies in the setting of hemodynamic compromise.

Abstract: The Guangzhou Twin Eye Study (GTES) is a population-based study of young twins residing in Guangzhou City. The major aim of GTES is to explore the impact of genes, environmental factors and gene-environment interactions on common eye diseases. From 2006, for more than 1,300 twin pairs, age 7–26 years old, progressive ocular phenotypes, such as refraction, ocular biometrics, weight, and height were collected annually, while non-progressive phenotypes such as parental refraction, corneal thickness, retinal fundus, intraocular pressure and DNA only collected at baseline. In the current study, we summarize the major findings on the etiology of myopia in recent decades.