Study of Myopia Correction Using Nanoporous Polymer Gas Permeable Contact Lenses

Ophthalmic treatments using contact lenses are now used by more and more specialists around the world. Improving contact lens (CL) materials is a condition that is constantly evolving. Contact lens materials are usually composed of polymer hydrogel or silicone hydrogel. The materials used for night contact lenses are gas permeable and they gradual flatten the center of the cornea which decreases the progression of myopia or myopic astigmatism. The aim of this study is to identify, in correlation with the chemical interactions between structural components of contact lenses and their biocompatibility with the surface layer and microtopography of the cornea or sclera, different incidents that occur in patients who have used rigid gas permeable contact lenses. The study was performed on a group of 10 patients who had a follow-up period between 4 and 6 years, who presented regularly for eye examinations. The following clinical parameters were analyzed: ocular refraction before and after wearing night contact lenses, types of contact lens materials, appearance of corneal topography, biomicroscopic examination of the anterior segment of the eye, keratometry, ocular comfort, as well as other incidents regarding this type of lenses. Difficulties caused by wearing contact lenses at night arose due to poor hygiene and maintenance in two cases or due to interruption of lens wear in one case.

Biocompatibility and Comfort during Extended Wear of Mel4 Peptide-Coated Antimicrobial Contact Lenses

(1) Purpose: This study aimed to investigate the effects of Mel4 antimicrobial contact lenses (MACL) on the ocular surface and comfort during extended wear. (2) Methods: A prospective, randomised, double-masked, contralateral clinical trial was conducted with 176 subjects to evaluate the biocompatibility of contralateral wear of MACL. The wearing modality was 14-day extended lens wear for three months. The participants were assessed at lens dispensing, after one night, two weeks, one month and three months of extended wear and one month after study completion. (3) Results: There were no significant differences (p > 0.05) in ocular redness or palpebral roughness between Mel4 and control eyes at any of the study visits. There was no significant difference (p > 0.05) in corneal staining between Mel4 and control eyes. There were no significant differences in front surface wettability or deposits or back surface debris (p > 0.05). No statistically significant differences (p > 0.05) were found in comfort, dryness, CLDEQ-8 scores lens or edge awareness. There was no evidence for delayed reactions on the ocular surface after cessation of lens wear. (4) Conclusion: The novel MACLs showed similar comfort to control lenses and were biocompatible during extended wear. Thus, these lenses were compatible with the ocular surface.

REGIONAL VARIATION IN FLUID RESERVOIR THICKNESS, OXYGEN TRANSMISSIBILITY AND CORNEAL OEDEMA DURING SCLERAL LENS WEAR

Purpose: To determine if regional variation in post lens fluid reservoir thickness (PLFT) during scleral lens wear leads to regional variation in oxygen transmissibility and corneal edema during 4 hours of non-fenestrated scleral lens wear.Methods: About 20 healthy subjects (mean age, 28.8 ± 4.2 years) were fitted with nonfenestrated rotationally symmetric scleral lenses. Anterior segment optical coherence tomography was used to measure cornea thickness before and after lens wear, PLFT 10 minutes and 4 hours after lens application, and scleral lens thickness (with the scleral lens in situ) 4 hours after scleral lens application. These measurements were limited to the central 6 mm and divided into three zones (central, mid-peripheral, and peripheral zones). In the mid-peripheral and peripheral zones, eight principal meridians were measured, generating 17 measurement points in total. Scleral lens thickness and PLFT measurements were corrected for optical distortions by a series of equations. Oxygen transmissibility was calculated by dividing the scleral lens oxygen permeability by the optically-corrected scleral lens thickness, taking into account the oxygen permeability of saline and fluid reservoir thickness.Results: A significant regional variation in PLFT (F = 12.860, P = 0. 012) was observed after 10 minutes of the lens application, PLFT was thickest and thinnest in the inferotemporal and the superonasal region of the peripheral zones( 322.6 ± 161.8 µm and 153.8 ± 96.4 µm, respectively); however, this variation was not statistically significant at 4 hours of scleral lens wear (F = 4.692; P = 0.073). Despite significant regional variation in oxygen transmissibility (F = 48.472; P = 0.001) and relatively low oxygen transmissibility through the scleral lens, induced corneal edema did not vary significantly in different regions (F = 3.346; P = 0.126). In the central corneal region, the induced corneal edema correlated moderately with PLFT (r = 0.468; P = 0.037) and oxygen transmissibility (r = -0.528; P = 0.017). This relationship was insignificant in the peripheral cornea.Conclusion: The inferotemporal peripheral region had the thickest PLFT and least oxygen transmissibility, and the superonasal region had the vice versa. Despite significant variation in PLFT and oxygen transmissibility initially, in healthy corneas, this variation does not seem to induce statistically significant regional variation in corneal edema. Increased central PLFT and decreased oxygen transmissibility moderately correlate with central corneal edema.

A new approach for quantifying epithelial and stromal thickness changes after orthokeratology contact lens wear

The aim of the study was to develop an automatic segmentation approach to optical coherence tomography (OCT) images and to investigate the changes in epithelial and stromal thickness profile and radius of curvature after the use of orthokeratology (Ortho-K) contact lenses. A total of 45 right eyes from 52 participants were monitored before, and after one month of, uninterrupted overnight Ortho-K lens wear. The tomography of their right eyes was obtained using optical OCT and rotating Scheimpflug imaging (OCULUS Pentacam). A custom-built MATLAB code for automatic segmentation of corneal OCT images was created and used to assess changes in epithelial thickness, stromal thickness, corneal and stromal profiles and radii of curvature before, and after one month of, uninterrupted overnight wear of Ortho-K lenses. In the central area (0–2 mm diameter), the epithelium thinned by 12.8 ± 6.0 µm (23.8% on average, p < 0.01) after one month of Ortho-K lens wear. In the paracentral area (2–5 mm diameter), the epithelium thinned nasally and temporally (by 2.4 ± 5.9 µm, 4.5% on average, p = 0.031). The stroma thickness increased in the central area (by 4.8 ± 16.1 µm, p = 0.005). The radius of curvature of the central corneal anterior surface increased by 0.24 ± 0.26 mm (3.1%, p < 0.01) along the horizontal meridian and by 0.34 ± 0.18 mm (4.2%, p < 0.01) along the vertical meridian. There were no significant changes in the anterior and posterior stromal radius of curvature. This study introduced a new method to automatically detect the anterior corneal surface, the epithelial posterior surface and the posterior corneal surface in OCT scans. Overnight wear of Ortho-K lenses caused thinning of the central corneal epithelium. The anterior corneal surface became flattered while the anterior and posterior surfaces of the stroma did not undergo significant changes. The results are consistent with the changes reported in previous studies. The reduction in myopic refractive error caused by Ortho-K lens wear was mainly due to changes in corneal epithelium thickness profile.

Corneal Scheimpflug topography values to distinguish between normal eyes, ocular allergy, and keratoconus in children

To identify and compare keratometric, corneal thickness, and elevation parameters and indices among healthy children, ocular allergy, and keratoconus using the OCULUS Pentacam Scheimpflug topography system. This study included healthy children, children with ocular allergy (OA) without keratoconus, and children with keratoconus (KC). The study design consisted of a prospective evaluation and review of medical records from a Brazilian ophthalmology department. The exclusion criteria were inability to undergo the ocular exam, other ocular diseases, contact lens wear, and topographic corneal ectasia. The effect of each corneal parameter was evaluated using univariate and multivariate logistic regression models adjusted for sex and age, and ROC curves were used to assess the ability each variable to discriminate among groups. A total of 182 subjects were included: healthy children (n = 99), children with OA (n = 32), and children with KC (n = 51). Groups differed in terms of sex, with more males in the OA group (73.2%) and the KC group (67.7%) than in the control group (40.9%). All corneal parameters studied differed significantly between the control and KC groups, and between the OA and KC groups; they also differed significantly between the three groups in terms of astigmatism, q-value, CCT, TP, BAD-D, and ARTmax values. We present the first study to describe and compare corneal tomographic parameters in healthy children, OA, and KC. Keratometry indices, ACD, ARTmax, AETP, and PETP were found to be the most useful for differentiating between healthy and KC children.IBR registry number: CAAE 54921916.9.0000.5404.

MICROBIAL BIOBURDEN OF ORTHOKERATOLOGY AND HYDROGEL CONTACT LENSES AND STORAGE CASES USING A HYDROGEN-PEROXIDE DISINFECTING SYSTEM

Background and objective: The fitting of orthokeratology (ortho-k) and multifocal soft contact lenses (SCL) is becoming increasingly popular worldwide for reducing the rate of myopia progression. However, overnight wear use of lenses and microbial contamination of contact lenses and storage vials has been shown to increase the risk of corneal inflammatory and infiltrative events (CIEs). Therefore, we conducted a pilot study to compare the rate, level, and type of microbial contamination of contact lenses and storage vialswhen participants wear ortho-k and SCL in combination with a hydrogen-peroxide disinfecting system. Material and Methods: A prospective, single-centre, randomized, crossover study was conducted to evalu-ate the rate and level of contact lens and storage vials contamination during the use of ortho-k and SCL along with a hydrogen-peroxide disinfecting solution over two 10 day wearing periods. Ocular signs and symptoms were assessed during lens wear at baseline and after each wearing period. In addition, contact lens and storage vials were collected, and the type and amount of microbial contamination were evaluated using viable culture and standard identification methods.Results: Twenty-five adults were enrolled, and 21 completed the study. One (5%) ortho-k lens, five (24%) ortho-k storage vials, one (5%) SCL and one (5%) SCL storage vial were contaminated (P > 0.05), predominantly with Gram-positive bacteria. None of the participants had contamination with both ortho-k and SCL. No significant differences were found between the ocular signs, including conjunctival redness and roughness, or conjunctival or corneal staining (all P > 0.05), irrespective of using ortho-k or SCL. Conclusion: This study provides the first data that directly compares microbial contamination of ortho-K versus SCL in patients using a hydrogen-peroxide disinfection system. However, the overall microbial contamination rate of contact lens storage vials was much lower (30%) than the previously reported study with ortho-k lens wear. The results support conducting a larger clinical trial designed to understand differences in microbial contamination with different lens materials and modalities.