A Corneal Biomechanical Study Measured with a Scheimpflug Dynamic Analyser in Soft Contact Lens Wearers.

The aim of this study was to evaluate the biomechanical changes in the cornea after wearing soft contact lenses (CLs) in healthy myopic patients measured with a Corvis ST® (CST, Oculus Optikgeräte GmbH, Wetzlar, Germany) analyser. This prospective, cross-sectional, single-centre study was performed on twenty-two Caucasian patients aged between 19 and 24 years (20.64 ± 1.21 years) range. Five device-specific biomechanical parameters, the central corneal thickness (CCT), and biomechanically corrected intraocular pressure (bIOP) were measured prior to fitting and one month after CL wear. Differences between the means of the deflection amplitude ratio (DA Ratio) and the standard deviation of the DA Ratio (SD DA Ratio) pre- and post-CL wear were found to be significant (p value = 0.002 in both cases). Significant differences were found between pre- and post-CL wear values in CCT (p value = 0.013). For all other biomechanical measures, no significant differences were observed before and after treatment. A significant association was found between changes in bIOP and classification according to changes in Int. Radius (p value = 0.047) and SSI (p value = 0.026) standard deviations. The corneal biomechanical indices provided by CST demonstrate that the fitting of soft CLs is a safe optical compensation method for the stability of corneal stiffness. No significant differences were found pre- and post-CL wear in the assessment of bIOP.

Key Factors in Early Diagnosis of Myopia Progression within Ocular Biometric Parameters by Scheimpflug Technology.

The aim of this study was to evaluate the relationship between myopia and ocular biometric variables using the Pentacam AXL® single rotation Scheimpflug camera. This prospective, cross-sectional, single-center study was performed in fifty Caucasian patients aged between 18 and 30 years (24.84 ± 3.04 years). The measured variables included maximum and minimum keratometry (K1 and K2, respectively), anterior chamber depth (ACD), corneal horizontal diameter or white to white (WTW), central corneal thickness (CCT), corneal asphericity (Q), and axial length (AXL). The tomographic and biometric measurements were considered optimal when the quality factor was greater than 95% according to the manufacturer's software instructions. The AXL presented a significant correlation with the spherical equivalent without cycloplegia (SE without CP), age at onset of myopia (r = -0.365, p = 0.012), mean keratometry (Km) (r = -0.339, p = 0.016), ACD (r = 0.304, p = 0.032), and WTW (r = 0.406, p = 0.005). The eyes with AXL higher than 25 mm had earlier onset; higher SE without CP, AXL, and Q; and a flatter Km. AXL is the biometric variable with the greatest influence on the final refractive state in the adult myopic eye. Ophthalmologists and optometric management must consider these biometric differences in order to identify the most appropriate correction techniques in each case. The use of the Pentacam AXL in ocular biometric measurement is effective, reproducible, and non-invasive.

Effect of macular pigment carotenoids on cognitive functions: A systematic review.

Lutein and zeaxanthin-xanthophyll carotenoids with antioxidant and anti-inflammatory characteristics-are present in the retina and the brain. High concentrations of these carotenoids have been positively related to cognitive performance. Therefore, this systematic review analyses the relationship between macular pigment density and cognitive functions. Most relevant databases were scoured for studies on healthy people relating cognitive functions to macular pigment optical density (MPOD). There were no age, sex, or race limitations. PROSPERO registration: CRD42021254833. Nineteen studies were included, seven randomized controlled trials (RCT) and eleven observational studies. The general aim of the studies was to examine the association between carotenoids (lutein, meso­zeaxanthin and zeaxanthin) and cognitive function. Most observational studies correlates MPOD levels with cognitive function or brain activity. Besides, RCTs compared the cognitive function and/or brain activity after increasing lutein and zeaxanthin intake though dietary supplementation or avocado consumption. Dietary lutein and zeaxanthin intake increased MPOD in six of the seven clinical trials and significantly improved most of the cognitive functions studied. A wide variety of test and methodologies for measuring cognitive functions were observed. Memory, processing speed, attention and reasoning were the cognitive function significantly related to MPOD levels in adults. Brain activity also was related to MPOD, but the results were inconsistent. Only four of the eleven observational studies were based on young people and all studies showed a significant relationship between MPOD and cognitive functions. This systematic review showed a direct relationship among cognitive functions, macular pigment and the intake of lutein and zeaxanthin.

Complications and Explantation Reasons in Intracorneal Ring Segments (ICRS) Implantation: A Systematic Review.

PURPOSE: To review the intraoperative and postoperative complications after intracorneal ring segment implantation and to report the explantation rate among the available scientific literature. METHODS: Three different databases (PubMed, Web of Science, and Scopus) were assessed from January 1995 to June 2019. The keywords used were: ring, rings, ICRS (intracorneal ring segments), segment, segments or Intacs, complication, explantation, explanted, retired, and removal. RESULTS: The selection process of this systematic review study is described in a flow diagram. A total of 39 studies published between 1995 and 2019 were included. Sixteen studies were case reports, 21 were case series studies, and 2 were chart analysis works. This study enrolled 1,946 participants, and 2,590 eyes were included. The postoperative complications described in most studies included migration, ring extrusion, corneal thinning, corneal melting, and some type of infective keratitis. These complications together with glare, halos, fluctuating vision, neovascularization, foreign body sensation, or pain represented most of the causes. The percentage rate of explantation ranged from 0.5% up to 83.3%. If we analyze those articles with a high number of implantations (2,124 eyes), an explantation rate between 0% and 1.4% was obtained. CONCLUSIONS: The complication rate and explantation ratio in segments of the intracorneal ring segments analyzed in the available scientific literature are minimal. Therefore, patient selection, surgery planning, and postoperative follow-up are critical to the success of surgery. [J Refract Surg. 2019;35(11):740-747.].