Abstract: Contrast is the differential luminance between one object and another. Contrast sensitivity (CS) quantifies the ability to detect this difference: estimating contrast threshold provides information about the quality of vision and helps diagnose and monitor eye diseases. High contrast visual acuity assessment is traditionally performed in the eye care practice, whereas the estimate of the discrimination of low contrast targets, an important complementary task for the perception of details, is far less employed. An example is driving when the contrast between vehicles, obstacles, pedestrians, and the background is reduced by fog. Many conditions can selectively degrade CS, while visual acuity remains intact. In addition to spatial CS, “temporal” CS is defined as the ability to discriminate luminance differences in the temporal domain, i.e., to discriminate information that reaches the visual cortex as a function of time. Likewise, temporal sensitivity of the visual system can be investigated in terms of critical fusion frequency (CFF), an indicator of the integrity of the magnocellular system that is responsible for the perception of transient stimulations. As a matter of fact, temporal resolution can be abnormal in neuro-ophthalmological clinical conditions. This paper aims at considering CS and its application to the clinical practice.
Background: To evaluate the association between corneal central endothelial cell count (CECC) with reactivity for hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), human T-lymphotropic virus-1 (HTLV1), and syphilis from an eye bank database.
Methods: Eye bank data included 19,159 donors and 38,318 corneas screened for HBV, HCV, HIV, HTLV1, and syphilis from July 2007–May 2015. Linear and binary mixed effects models were used to determine the adjusted marginal effect a positive viral screening test had on CECC and morphology, respectively. The models were adjusted for age, race, gender, lens status, and death to preservation. Eyes with missing data were excluded from the analysis. Statistical significance was defined as P values <0.05.
Results: A total of 18,097 donors and 35,136 corneas were included in the final analysis. Average CECC for eyes with negative viral screening was 2,597±436 while the average CECC for eyes screening positive for syphilis, HBV, HCV, HIV, and HTLV1 were 2,638±392 (P=0.073), 2,569±419 (P=0.815), 2,603±363 (P=0.207), 2,615±360 (P=0.733), and 2,625±436 (P=0.362) respectively.
Conclusions: The presence of HBV, HCV, HIV, HTLV1, and syphilis display no association with a statistically significant difference in CECC when compared to normal non-diseased donors.
Abstract: Ophthalmology residency training programs need authentic methods of assessment to show that trainees have learned and can do what is expected upon graduation. Written and oral examinations are necessary to assess knowledge but other methods are needed to assess skill. Workplace-based assessments (WPBAs) should be utilized to observe resident skill in the clinic and during surgery. Several such assessment tools have been published and validated. These tools have the additional benefit of facilitating specific formative feedback and thus can be used for both teaching and assessing.
Abstract: The outcomes of modern ophthalmic surgery, especially cataract surgery, continue to improve and patients now realistically expect an excellent and speedy outcome with good vision and few complications. Social and regulatory demands for greater transparency and accountability in medicine have increased, highlighting a fundamental ethical tension in medical education—balancing the needs of trainees (who have not yet mastered the technique) to gain experience by performing surgery, with patient safety and the needs of the public to be protected from risk. Patient safety and well-being are the paramount considerations in any training program and must be the first consideration in program design. A variety of different educational strategies, each implemented with the aim of improving operative skills assessment and teaching, has recently been described in the literature. Effective use of these educational tools, combined with a structured approach to teaching and providing meaningful feedback, could improve outcomes, decrease complications and improve the quality and efficiency of surgical training in ophthalmology. Supervisors must assess their teaching style and communication, as being a good surgeon does not necessarily make a good trainer. Open disclosure must be given to patients about who will be performing the surgery, and communication during surgery between supervisors and trainees must be clear, respectful and appropriate.
Background: To investigate the effect of sirolimus (SRL) eye drops on acute alkali-burn-induced corneal neovascularization (CNV) and explore its possible mechanism.
Methods: A total of 57 male Sprague-Dawley rats weighing 160–180 g were randomly divided into four groups including a normal control group (NC group, n=12), an untreated alkali-burned model control group (MC group, n=15), a blank eye drop treatment group (BT group, n=15), and an SRL eye drop treatment group (ST group, n=15). Corneal inflammation and CNV were observed and scored under a slit-lamp microscope 3, 7, and 14 days after alkali exposure. Three rats were randomly sacrificed in each group before modeling and 3, 7, 14 days after modeling, and the corneas of right eyes were harvested for Western blotting to compare the expression levels of VEGFR2 and caspase-3.
Results: Corneal inflammation scoring showed that the corneal edema and conjunctival congestion were severe in the MC, BT, and ST groups 1 day after alkali exposure but were alleviated at day 3. The corneal transparency was significantly higher in the ST group than in the MC and BT groups at days 7 (F=9.77, P<0.05) and 14 (F=5.81, P<0.05). At day 1, the corneal limbal vascular network was markedly filled. SNV was obvious at days 3, 7, and 14. The new blood vessels were shorter and sparser in the ST group than in the MC and BT groups, and the CNV scores showed significant differences among these groups (day 3: F=8.60, P<0.05; day 7: F=11.40, P<0.05; and day 14: F=41.59, P<0.01). Western blotting showed that the expressions of VEGFR2 and caspase-3 were low before modeling and showed no significant difference among the different groups (F=0.52, P>0.05; F=0.98, P>0.05). The corneal expression of VEGFR2 became significantly higher in the MC and BT groups than in the ST group 3, 7, and 14 days after alkali exposure, and there were significant differences in relative gray-scale values among these groups (day 3: F=32.16, P<0.01; day 7: F=85.96, P<0.01; day 14: F=57.68, P<0.01). The increase in the corneal expression of caspase-3 was significantly larger in the ST group than in the MC and BT groups at days 3, 7, and 14, and there were significant differences in relative gray-scale values among groups (day 3: F=32.16, P<0.01; day 7: F=53.02, P<0.01; day 14: F=38.67, P<0.01).
Conclusions: SRL eye drops can alleviate acute alkali-burn-induced corneal inflammation and inhibit alkali-burn-induced CNV in rat models. It can reduce VEGFR2 expression and increase caspase-3 expression in the corneal tissue, which may contribute to the inhibition of alkali-burn-induced CNV.
Abstract: The efficacy of selective laser trabeculoplasty (SLT) to treat open-angle glaucoma (OAG) and ocular hypertension (OHT) has been increasingly substantiated lately. Repeated SLT is usually needed to control intraocular pressure (IOP), be it as primary or adjunctive therapy. We review the studies available, in terms of SLT repeatability; and conclude comparable efficacy, with success rate, duration and complications similar to those in initial SLT.
Abstract: Cataract surgery is one of the most commonly performed surgeries among the elderly today. The volume of cataract surgeries has dramatically increased in the past few decades due to technological advancements leading to decreased morbidity, better overall outcomes, and increased expectation for correction of refractive error and spectacle independence after cataract surgery. The number of cataract surgeries is expected to continue to rise with the increase of the elderly population. Thus, accurate predictions of intraocular lens (IOL) power and the ability to correct for any postoperative refractive errors are critical. Despite the improved ability of cataract surgeons to accurately calculate IOL power, postoperative refractive errors still do occur due to various reasons such as imperfect preoperative measurements, toric-lens misalignment, and existing or surgically-induced astigmatism. The aim of this article is to review the various surgical options, including intraocular and corneal refractive surgical approaches, to correct post-operative refractive errors after cataract surgery.
