Control Contact Lenses Research Articles

Ocular and corneal aberrations changes in controlled randomized clinical trial MiSight\xae Assessment Study Spain (MASS)

BackgroundTo compare ocular and corneal inherent aberrations in the naked eyes of randomly selected children fitted with MiSight contact lenses (CL) for myopia control, versus children corrected with single-vision spectacles (control), over a 24-months period.MethodsChildren aged 8 to 12 years, with myopia (-0.75 to -4.00 D sphere) and astigmatism (< -1.00 D cylinder) were randomly assigned to the lens study group (MiSight) or the control group (single-vision spectacles). The root mean square aberration (RMS) was determined as corneal (RMS_C), corneal high order RMS (HO_RMS_C), corneal low order RMS (LO_RMS_C), ocular (total) RMS (RMS_T), ocular high order RMS (HO_RMS_T), ocular low order RMS (LO_RMS_T), corneal spherical aberration (SA_C) and ocular SA (SA_T) were calculated by aberrometry measures at the baseline, on 12-months and 24-months visits. A 5 mm diameter was defined for the analysis in all visits for all subjects. Only the dominant eye was analyzed.ResultsSeventy-four subjects completed the clinical trial: 41 subjects from the MiSight group (age: 11.01 ± 1.23 years) and 33 from the single-vision group (age: 10.12 ± 1.38 years). RMS_T significantly changed (0.57 ± 0.20 µm, p = 0.029) after 24-months in the control group. In the MiSight group no significant changes were registered (p > 0.05). The SA_C and SA_T did not reveal significant changes between visits or between groups (p > 0.05).ConclusionsAlong 2 years, MiSight CL did not induce significant changes in RMS of anterior cornea or total ocular RMS. Contrary, in control group the RMS_T significantly changed as response of greater eye growth and myopia progression. The results obtained in present study allow to predict corneal or total aberration changes, in children, in response of wearing of MiSight lens along the time.Trial registration: ClinicalTrials.gov Identifier: NCT01917110.

Patient experience and physiological response to two commercially available daily disposable myopia control contact lenses

BackgroundA range of myopia management (MM) contact lenses are becoming available to practitioners. These lenses are designed to slow myopia progression and axial elongation. This study explored the initial experience of participants wearing daily disposable MM contact lenses to investigate established factors previously associated with successful lens wear. MethodsThis was a prospective, double-masked, crossover study. Twenty participants aged 18–30 years old were assigned to wear two daily disposable MM lenses in a randomised order. Visual acuity, contrast sensitivity, and amplitude/lag of accommodation were assessed at baseline, post-insertion, and after 2 and 6 h of lens wear. Self-reported lens comfort and vision quality were recorded at the same timepoints, and at 10 h post-insertion. Pairwise comparisons were performed between the two lenses at each timepoint, as well as assessing changes throughout wear. The relationship of the measured parameters to overall lens satisfaction was also assessed. ResultsThere were no significant differences between the two MM lenses at any timepoint for any of the participant-reported parameters, including overall satisfaction. A small difference in visual acuity was noted at 6 h post-insertion, although this is unlikely to be clinically significant. Comfort decreased throughout the day, most notably at 10 h post-insertion. A moderate positive correlation was observed between participant-reported visual quality and overall satisfaction. A similar pattern was seen for comfort and overall satisfaction. Self-reported vision quality and measured visual acuity were poorly correlated, highlighting the benefit of subjectively assessing the quality of vision with these lenses. ConclusionsThe participants demonstrated comparable measures across a range of measures between the two MM lenses. Notably, half of the participants demonstrated a clear lens preference, although the preferred lens varied between individuals. Candidates for MM may benefit from trialling more than one MM lens design, to maximise initial wearing satisfaction.

Power profiles of centre-distance multifocal soft contact lenses.

Centre-distance multifocal contact lenses (MFCLs) for myopia control are thought to slow myopia progression by providing both clear foveal vision and myopic defocus. Characterising the power profile of lenses is important to understanding their possible effects on retinal defocus when worn. The power profiles of three commercially available MFCLs were determined. Three centre-distance MFCL designs were studied: Biofinity Multifocal D +2.50 add (comfilcon A), Proclear Multifocal D +2.50 add (omafilcon A), and NaturalVue Multifocal (etafilcon A). Two lenses each in power from -1.00D to -6.00D in 1D steps were stored in ISO 18369-3:2017 standard phosphate buffered saline for 24h. Optical power profiles were measured in a wet cell with the SHSOphthalmic profiler accounting for centre thickness and manufacturer-reported material refractive index. Sagittal power maps from the SHSOphthalmic were exported, and custom MATLAB code was used to generate power profiles by averaging along the vertical and horizontal meridians. One-way anova with Tukey's HSD post-hoc t-tests were used to analyse maximum add power by lens design. Plus power increased out from the lens centre for all three MFCLs. Power profiles of Biofinity D and Proclear D MFCLs show three distinct areas within the optic zone; the distance zone (from lens centre to about 1.6mm radius), intermediate zone (about 1.6mm radius to 2.1mm) and near zone (about 2mm radius to 4mm). For NaturalVue MFCLs, plus power starts increasing almost immediately from the lens centre, reaching maximum measured mean plus power at a radius of 2.7mm. From 2.7mm to 3.0mm, there was a decrease in plus power, which was then generally maintained out to the optic zone edge. Across all lens powers, maximum add power was highest with the NaturalVue MFCL (+3.32±0.44D), then Proclear D (+1.84±0.28D) and Biofinity D (+1.47±0.34D) MFCLs (all p<0.04). Add power peaked at different locations for different lens powers and designs. Power profiles of MFCLs vary based on lens design and power. These power profiles are consistent with reported myopic and hyperopic changes in peripheral refraction with MFCLs and provide some explanation for reported differences in peripheral refraction with these MFCLs. Further work is needed to determine whether these power profile differences influence myopia progression.

Exploring non-adherence to contact lens wear schedule: Subjective assessments and patient related factors in children wearing single vision and myopia control contact lenses

PurposeTo determine factors associated with non-adherence to contact lens wear schedule involving single vision and myopia control contact lenses in children. MethodsData from 379 children enrolled in a prospective, double masked, randomized clinical trial, aged 8–13 years, cycloplegic spherical equivalent of -0.75 to -3.50D and wearing either: single vision silicone hydrogel (SiH) CL (control lens); two anti-myopia SiH CL that incorporated relative plus in the central and periphery in a stepped manner (test lens I and II); and two extended depth of focus hydrogel CL (test lens III and IV) was considered. A questionnaire was administered to the participants at every scheduled visit and gathered information on days of wear/week and subjective assessments of ocular comfort and visual quality on an analog scale of 1–10.Participants were categorized as “Adherent” when lens wear was ≥ 6 days/week or “Non-adherent” when lens wear ≤ 5 days/week. Categorized adherence data was summarized as a percentage across visits for each CL type. Differences between the two groups were analyzed using linear mixed model. ResultsFor the control lens, 79.6 % participants were adherent as compared to 63.7%–74.6% with test lenses (p=0.026). Non-adherence was greater in those that discontinued (p<0.001). Subjective ratings of visual quality for static and dynamic tasks were lower with non-adherent wearers and more variable between visits. Ocular comfort was also poorer in non-adherent wearers irrespective of lens material or lens design. Male gender, lower baseline myopia, lower high contrast visual acuity and esophoria were associated with a higher risk of non-adherence. ConclusionsThe study identified a wide range of factors associated with non-adherence to lens wear schedule. Paying specific attention to these factors when evaluating patients for CL wear and taking steps to ensure satisfaction in lens wear may promote longer term continuation of wear.

Nasal-temporal asymmetry in peripheral refraction with an aspheric myopia control contact lens.

A combination of human subject data and optical modelling was used to investigate unexpected nasal-temporal asymmetry in peripheral refraction with an aspheric myopia control lens. Peripheral refraction was measured with an auto-refractor and an aberrometer. Peripheral refraction with the lens was highly dependent upon instrument and method (e.g. pupil size and the number of aberration orders). A model that did not account for on-eye conformation did not mirror the clinical results, but a model assuming complete lens conformation to the anterior corneal topography accounted for the positive shift in clinically measured refraction at larger nasal field angles. The findings indicate that peripheral refraction of highly aspheric contact lenses is dependent on lens conformation and the method of measurement. These measurement methods must be reported, and care must be used in interpreting results.

Comparison of short-term light disturbance, optical and visual performance outcomes between a myopia control contact lens and a single-vision contact lens.

To compare the optical and visual performance of a dual-focus (DF) contact lens used for myopia control with a single-vision (SV) contact lens of the same material. A randomised, double-masked crossover study. Twenty-eight healthy, myopic volunteers between 18 and 32years of age (23.49±4.07years) participated in this study. The sensory dominant eye for distance vision was determined. Refraction, best-corrected visual acuity (VA) and aberrations for 3mm and 5mm pupil diameters were quantified without a contact lens in situ. Subjects were fitted with two contact lens designs: DF and SV, both made of omafilcon A material. The Quality of Vision (QoV) questionnaire, over-refraction, best-corrected VA, stereopsis at 40cm, best-corrected photopic and mesopic contrast sensitivity, light disturbance and aberrations were assessed 25min after contact lens insertion. There were no statistically significant differences in best-corrected VA and stereopsis between the baseline, DF and SV conditions. Photopic and mesopic contrast sensitivity were lower for the DF contact lens at all frequencies, with the exception of the mesopic contrast sensitivity at 18 cycles per degree (p=0.23). Higher order aberrations and light disturbance size and irregularity were higher for the DF contact lens (p<0.001). No differences were found in higher order aberrations between baseline and the SV contact lens condition for each pupil diameter. QoV scores also revealed lower frequency, severity and bothersome scores with the SV contact lens than with the DF contact lens (p<0.001). The DF contact lens design decreased the psychophysical and psychometric visual quality scores in the short-term under dim-light conditions when compared with a single-vision contact lens design of the same material. VA and stereopsis were unaffected by the lens design.

Orthokeratology for myopia control in Covid-19 era

Philip Morgan, Lyndon Jones and Kate Gifford evaluate considerations on using orthokeratology contact lenses for myopia control during the Covid-19 pandemic

The Effects of a Senofilcon A Contact Lens With and Without a Photochromic Additive on Positive Dysphotopsia Across Age.

Objective:The visual effects of wearing a photochromic contact lens (test) were directly compared with a nonphotochromic contact lens (control). Positive dysphotopsia (halos, starbursts) and intraocular scatter (behaviorally determined) were assessed. Both younger and middle-aged subjects were evaluated to examine the influence of age.Methods:Fifty-four subjects (18–62 years) were tested using a contralateral design. Subjects were fit with a photochromic contact lens on one eye and a nonphotochromic contact lens on the other eye, randomly assigned. Testing occurred with and without photochromic activation (darkened) by use of a violet activator (365 nm, half-bandwidth 20 nm). The extent of dysphotopsia (halos and spokes) was measured using an aperture (∼4 mm) that created a bright point source of light 45 inches from the plane of the eye. Between the point source and subject, a centering precision caliper was used to measure lateral spread. Two-point thresholds were determined by measuring the minimum distance between two points of broadband xenon light.Results:The photochromic contact lens produced smaller halo diameters than the control contact lens, both activated (41% on average) and inactivated (21% on average), and age strata was a significant factor (P<0.001) with the older group showing a greater reduction. The photochromic contact lens produced smaller starburst diameters than the control contact lens, both activated (37% on average) and inactivated (23% on average), and age strata was a significant factor (P=0.001) with the older group showing a greater reduction. The two-point thresholds were reduced (25% activated, 9% inactivated) on average but the age effect was not significant (P<0.10).Conclusions:The senofilcon A lens with photochromic additive reduced the extent of positive dysphotopsia compared with the same lens without the additive, regardless whether the lens was activated or not. The visual benefit was greatest with the older subjects.

Bifocal and Multifocal Contact Lenses for Presbyopia and Myopia Control.

Bifocal and multifocal optical devices are intended to get images into focus from objects placed at different distances from the observer. Spectacles, contact lenses, and intraocular lenses can meet the requirements to provide such a solution. Contact lenses provide unique characteristics as a platform for implementing bifocality and multifocality. Compared to spectacles, they are closer to the eye, providing a wider field of view, less distortion, and their use is more consistent as they are not so easily removed along the day. In addition, contact lenses are also minimally invasive, can be easily exchangeable, and, therefore, suitable for conditions in which surgical procedures are not indicated. Contact lenses can remain centered with the eye despite eye movements, providing the possibility for simultaneous imaging from different object distances. The main current indications for bifocal and multifocal contact lenses include presbyopia correction in adult population and myopia control in children. Considering the large numbers of potential candidates for optical correction of presbyopia and the demographic trends in myopia, the potential impact of contact lenses for presbyopia and myopia applications is undoubtedly tremendous. However, the ocular characteristics and expectations vary significantly between young and older candidates and impose different challenges in fitting bifocal and multifocal contact lenses for the correction of presbyopia and myopia control. This review presents the recent developments in material platforms, optical designs, simulated visual performance, and the clinical performance assessment of bifocal and multifocal contact lenses for presbyopia correction and/or myopia progression control.

The relationship between environmental sources and the susceptibility of Acanthamoeba keratitis in the United Kingdom.

To determine whether Acanthamoeba keratitis (AK) patients have higher rates of Acanthamoeba and free-living amoeba (FLA) colonising domestic sinks than control contact lens (CL) wearers, and whether these isolates are genetically similar to the corneal isolates from their CL associated AK. 129 AK patients from Moorefield Eye Hospital, London and 64 control CL wearers from the Institute of Optometry were included in this study. The participants self-collected home kitchen and bathroom samples from tap-spouts, overflows and drains using an instructional kit. The samples were cultured by inoculating onto a non-nutrient agar plate seeded with Escherichia coli, incubated at 32°C and examined for amoebae by microscopy for up to 2 weeks. Partial sequences of mitochondrial cytochrome oxidase genes (coxA) of Acanthamoeba isolates from four AK patients were compared to Acanthamoeba isolated from the patient's home. The association between sampling sites was analysed with the chi-square test. A total of 513 samples from AK patients and 189 from CL controls were collected. The yield of FLA was significantly greater in patients' bathrooms (72.1%) than CL controls' bathrooms (53.4%) (p<0.05). Spouts (kitchen 6.7%, bathroom 11%) had the lowest rate of Acanthamoeba isolation compared to drains (kitchen 18.2%, bathroom 27.9%) and overflow (kitchen 39.1%, bathroom 25.9%) either in kitchens or bathrooms (p<0.05). There was no statistically significant difference between the average prevalence of Acanthamoeba in all three sample sites in kitchens (16.9%) compared to all three sample sites in bathrooms (21.5%) and no association for Acanthamoeba prevalence between AK patients and CL controls. All four corneal isolates had the same coxA sequence as at least one domestic water isolate from the patients' sink of the kitchen and the bathroom. The prevalence of Acanthamoeba and FLA was high in UK homes. FLA colonisation was higher in AK patients compared to controls but the prevalence of Acanthamoeba between AK patients and CL controls domestic sinks was similar. This study confirms that domestic water isolates are probably the source of AK infection. Advice about avoiding water contact when using CL's should be mandatory.

A review of higher order aberrations of the human eye

Background: This literature review is part of a research study for aberration-correcting soft contact lenses, where wavefront aberrometry was utilised. Aim: This study was conducted as part of a postgraduate research degree by the first author with particular relevance to spherical aberrations in relation to myopia and soft contact lenses, both aberration control and non-control types. Setting: This study reports on a literature review of higher order aberrations. Methods: A comprehensive review of various databases was performed, including PubMed and Google Scholar in terms of aberration control contact lenses and particular customised contact lenses for compensation of spherical aberration in myopia, was performed. Results: Wavefront sensing and Zernike polynomials are increasingly used in optometry and ophthalmology to quantify the wavefronts for an optical system such as the eye, using either lower order (LOA) or higher order aberrations (HOA). Although other mathematical methods are available, zero, 1st and 2nd orders of the Zernike polynomial expansion are LOA. Defocus ( ) and astigmatism ( and ) are 2nd-order modes that usually can be corrected by clinicians using ordinary sphero-cylindrical compensations such as spectacle lenses. Until recently, only LOA were easily correctable by clinicians in optometry and ophthalmology. Higher order aberrations are those modes in the third radial order, n = 3 and higher, which in the past were not correctable. However, HOA contribute to only about 7% of retinal image quality and often go unnoticed by individuals, although in some instances, for example, with keratoconus or after refractive surgery, such aberrations can become more problematic. Today, new treatments are available via specially designed or customised (to an individual) rigid or soft contact lenses that are claimed to reduce or eliminate HOA such as spherical aberration ( ). Conclusion: Although such specially designed or customised contact lenses have some effect on HOA, there are conflicting reports and so further investigation of this intriguing aspect remains necessary.

Antibacterial and physical properties of a novel sonochemical-assisted Zn-CuO contact lens nanocoating.

This work examined the antibacterial and physical effects of a novel Zn-CuO nanocoating applied on a silicone hydrogel contact lens. Zn-CuO coating of PureVision balafilcon-A soft contact lenses (Bausch&Lomb, Rochester, NY) was performed by sonochemical deposition using a high-intensity ultrasonic horn. Non-coated PureVision lenses served as a control in all experiments. Adhesion assays for P. aerueginosa and S. epidermidis to the coated lenses were performed to identify the minimal coating concentration which still possessed antibacterial activity. Lens water content, oxygen transfer light transfer, leaching, and electron microscopy studies were performed using this concentration. Coated lenses showed 3-5 log reductions in adhesion of both species. The lowest tested coating concentration of 0.02wt% led to a log reduction of 3.25 ± 1.25 of P. aeruginosa CFU/lens (P = 0.007) and a log reduction of 4.37 ± 0.75 of S. epidermidis (p = 0.0007). Using this coating concentration, water content (36%, 33.6%), oxygen transfer (87.22 ± 10.96, 92.18 ± 2.38, × 10-11(cm2/s)(mlO2)/(ml × mmHg)), p = 0.12), and light transfer properties did not differ significantly between the coated and the control contact lenses. In the range of 380-780nm wavelength, the coated lenses transmitted 96.47 ± 1.52% while the control lenses transmitted 97.36 ± 1.35%. The corresponding values for the range of 300-380nm wavelength were 79.343 ± 8.754 and 80.169 ± 1.35. Leaching studies for 0.5mM coated lenses have demonstrated the excellent stability of the coating with the release of only 0.005% of the coating after 1week of exposure to the test solution. Sonochemical-assisted nanocoating of contact lenses showed significant and consistent antibacterial activity while preserving the basic properties of a silicone hydrogel contact lens.

Binocular and accommodative function in the controlled randomized clinical trial MiSight® Assessment Study Spain (MASS).

To evaluate the binocular and accommodative function in children wearing dual focus (DF) MiSight® contact lenses (CLs) for myopia control compared with children wearing single-vision (SV) spectacles. This was a randomized, controlled clinical trial involving subjects aged 8 to 12, with myopia ranging from - 0.75 to - 4.00D and astigmatism < 1.00D, allocated to MiSight® study CLs group or control group wearing SV. Binocular and accommodative function was determined at baseline, 12-, and 24-month visits, assessed by the following sequence of tests: distance and near horizontal phoria, accommodative convergence/accommodation (AC/A) ratio, stereopsis, accommodative amplitude (AA), and accommodative response (AR) at 33, 25 and 20 cm. Seventy-four children completed the study: 41 in the CL group and 33 in the SV group. CLs group did not show any significant differences in binocular and accommodative measurements throughout the study. In control group, distance and near phoria, stereopsis, AC/A and AR at 20cm did not show any significant change, but AA, AR at 33cm and AR at 25 cm were greater at 24-month visit compared with baseline (p < 0.05). DF lenses do not change the binocular and accommodative function in children wearing dual focus CLs. NCT01917110.

A Patient-Reported Outcomes (PRO) questionnaire for the paediatric soft contact lens wearers: Paediatric Contact Lens User Experience (pCLUE)

Purpose: With the increasing number of myopia control contact lens (CL) studies being conducted, a children specific PRO questionnaire to understand their subjective experience is needed. Currently, a validated PRO questionnaire specific for children is lacking. This study represented the initial work in developing a PRO questionnaire for children to measure the full range of comfort, vision and CL handling experience.

The Video Head Impulse Test and the Influence of Daily Use of Spectacles to Correct a Refractive Error

To determine the influence of daily use of spectacles to correct a refractive error, on the vestibulo-ocular reflex (VOR) gain measured with the video head impulse test (vHIT). This prospective study enrolled subjects between 18 and 80 years old with and without a refractive error. Subjects were classified into three groups: (1) contact lenses, (2) spectacles, and (3) control group without visual impairment. Exclusion criteria comprised ophthalmic pathology, history of vestibular disorders, and alternated use of spectacles and contact lenses in daily life. Corrective spectacles were removed seconds before testing. One examiner performed all vHIT's under standardized circumstances using the EyeSeeCam system. This system calculated the horizontal VOR gain for rightward and leftward head rotations separately. No statistically significant difference was found in VOR gain between the control group (n = 16), spectacles group (n = 48), and contact lenses group (n = 15) (p = 0.111). Both the spectacles group and contact lenses group showed no statistically significant correlation between VOR gain and amount of refractive error, for rightwards (p = 0.071) and leftwards (p = 0.716) head rotations. There was no statistical significant difference in VOR gain between testing monocularly or binocularly (p = 0.132) and between testing with or without wearing contact lenses (p = 0.800). In this study, VOR gain was not influenced by wearing corrective spectacles or contact lenses on a daily basis. Based on this study, no corrective measures are necessary when performing the vHIT on subjects with a refractive error, regardless of the way of correction.

A Randomized Trial of Soft Multifocal Contact Lenses for Myopia Control: Baseline Data and Methods.

The Bifocal Lenses In Nearsighted Kids (BLINK) study is the first soft multifocal contact lens myopia control study to compare add powers and measure peripheral refractive error in the vertical meridian, so it will provide important information about the potential mechanism of myopia control. The BLINK study is a National Eye Institute-sponsored, double-masked, randomized clinical trial to investigate the effects of soft multifocal contact lenses on myopia progression. This article describes the subjects' baseline characteristics and study methods. Subjects were 7 to 11 years old, had -0.75 to -5.00 spherical component and less than 1.00 diopter (D) astigmatism, and had 20/25 or better logMAR distance visual acuity with manifest refraction in each eye and with +2.50-D add soft bifocal contact lenses on both eyes. Children were randomly assigned to wear Biofinity single-vision, Biofinity Multifocal "D" with a +1.50-D add power, or Biofinity Multifocal "D" with a +2.50-D add power contact lenses. We examined 443 subjects at the baseline visits, and 294 (66.4%) subjects were enrolled. Of the enrolled subjects, 177 (60.2%) were female, and 200 (68%) were white. The mean (± SD) age was 10.3 ± 1.2 years, and 117 (39.8%) of the eligible subjects were younger than 10 years. The mean spherical equivalent refractive error, measured by cycloplegic autorefraction was -2.39 ± 1.00 D. The best-corrected binocular logMAR visual acuity with glasses was +0.01 ± 0.06 (20/21) at distance and -0.03 ± 0.08 (20/18) at near. The BLINK study subjects are similar to patients who would routinely be eligible for myopia control in practice, so the results will provide clinical information about soft bifocal contact lens myopia control as well as information about the mechanism of the treatment effect, if one occurs.

Tear Cytokine Levels in Contact Lens Wearers With Acanthamoeba Keratitis.

To determine differences in key tear film cytokines between mild and severe cases of acanthamoeba keratitis (AK) and control contact lens (CL) wearers. This was a prospective study of CL wearers with AK attending Moorfields Eye Hospital and control CL wearers from the Institute of Optometry, London. Basal tear specimens were collected by 10-μL capillary tubes (BLAUBRAND intraMark, Wertheim, Germany), and tear protein levels were measured with a multiplex magnetic bead array (Luminex 100; Luminex Corporation, Austin, TX) for cytokines interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-17A, IL-17E, IL-17F, IL-22, and interferon gamma and with enzyme-linked immunosorbent assay (Abcam, Cambridge, United Kingdom) for CXCL2. Severe cases of AK were defined as having active infection for over 12 months and at least 1 severe inflammatory event. One hundred and thirty-two tear samples were collected from a total of 61 cases (15 severe and 46 mild-moderate) and 22 controls. IL-8, part of the Toll-like receptor 4 cytokine cascade, was found to be expressed at a detectable level more often in cases of AK than in control CL wearers (P = 0.003) and in higher concentrations in severe cases than in milder forms of the disease (z = -2.35). IL-22, part of the IL-10 family, and a proinflammatory Th17 cytokine, was detected more often in severe cases than in milder forms of AK (P < 0.02). Profiling patients with AK during disease shows differences in cytokine levels between severe and milder disease that may inform clinical management. The Toll-like receptor 4 and IL-10/Th17 inflammatory pathways should be included in further investigations of this disease.

Microbial Contamination of Periorbital Tissues and Accessories of Children

To investigate normal flora of children with and without orthokeratology (ortho-k) treatment, and the associations between carriage of Staphylococcus aureus and Gram-negative rods with contamination of contact lenses and lens cases in ortho-k subjects and with spectacles of control subjects. Twenty-three ortho-k subjects (treatment >12 months) and 20 control myopic subjects aged 7-14 years were recruited. Samples were collected from four sites surrounding the left eye (lower conjunctiva, upper and lower eyelids, and eyelashes) for all subjects, spectacles for control subjects and contact lens accessories for ortho-k subjects. Samples were cultured, total numbers enumerated, and isolates identified using chromogenic agars. Ortho-k subjects had significantly less total isolates in the conjunctiva than controls (p = 0.009). Otherwise, carriage rates in normal flora levels of the peri-orbital tissues were not significantly different between the two groups (p > 0.19). The total isolates and carriage rates of normal flora on spectacles, contact lenses, and lens cases were similar to those identified on the skin tissues. Small numbers of bacteria were identified from the multipurpose solution of two ortho-k subjects. Although the association between the carriage of S. aureus with contamination of accessories was statistically significant only in control subjects (p = 0.03), ortho-k subjects not yielding S. aureus and Gram-negative rods from samples of their peri-orbital tissues tended to be less likely to have these organisms in their accessories. No Pseudomonas was isolated from any of the sites sampled and no Acinetobacter was isolated from any of the accessories. Ortho-k may lower the total number of bacteria in conjunctiva due to the use of solution and lenses, but the physiologic effect of this treatment on the types of normal flora in children was minimal and should not increase the risk of microbial keratitis in children with good compliance.

Nanoparticle-Laden Contact Lens for Controlled Ocular Delivery of Prednisolone: Formulation Optimization Using Statistical Experimental Design.

Human eye is one of the most accessible organs in the body, nonetheless, its physiology and associated precorneal factors such as nasolacrimal drainage, blinking, tear film, tear turnover, and induced lacrimation has significantly decreased the residence time of any foreign substances including pharmaceutical dosage forms. Soft contact lenses are promising delivery devices that can sustain the drug release and prolong residence time by acting as a geometric barrier to drug diffusion to tear fluid. This study investigates experimental parameters such as composition of polymer mixtures, stabilizer and the amount of active pharmaceutical ingredient on the preparation of a polymeric drug delivery system for the topical ocular administration of Prednisolone. To achieve this goal, prednisolone-loaded poly (lactic-co-glycolic acid) (PLGA) nanoparticles were prepared by single emulsion solvent evaporation method. Prednisolone was quantified using a validated high performance liquid chromatography (HPLC) method. Nanoparticle size was mostly affected by the amount of co-polymer (PLGA) used whereas drug load was mostly affected by amount of prednisolone (API) used. Longer homogenization time along with higher amount of API yielded the smallest size nanoparticles. The nanoparticles prepared had an average particle size of 347.1 ± 11.9 nm with a polydispersity index of 0.081. The nanoparticles were then incorporated in the contact lens mixture before preparing them. Clear and transparent contact lenses were successfully prepared. When the nanoparticle (NP)-loaded contact lenses were compared with control contact lenses (unloaded NP contact lenses), a decrease in hydration by 2% (31.2% ± 1.25% hydration for the 0.2 g loaded NP contact lenses) and light transmission by 8% (unloaded NP contact lenses 94.5% NP 0.2 g incorporated contact lenses 86.23%). The wettability of the contact lenses remained within the desired value (<90 °C) even upon incorporation of the NP. NP alone and NP-loaded contact lenses both displayed a slow in vitro drug release of drug over 24 h; where 42.3% and 10.8% prednisolone release were achieved, respectively. Contact lenses can be used as a medicated device to sustain ocular drug delivery and improve patient compliance; nonetheless, patients and healthcare professionals’ acceptability and perceptions of the new formulations entail further investigations.

Soft Contact Lenses with Positive Spherical Aberration for Myopia Control.

To determine whether soft contact lenses with positive spherical aberration (+SA) can slow myopia progression. Eligible subjects (N = 127, primarily Asian) aged 8 to 11 years were randomized to wear either control (spherical design) or test (with +SA) soft daily disposable contact lenses for a minimum of 1 and up to 2 years (treatment phase). Subjects from the initial cohorts (N = 82) were then followed for an additional 1.5 years while wearing a marketed spherical daily disposable contact lens (withdrawal phase). Axial length and spherical equivalent cycloplegic autorefraction (SECAR) were measured at baseline and every 6 months in both phases. During the first year of treatment, lens type (test vs. control) had a statistically significant impact on axial elongation (p = 0.0409). Eyes wearing test lenses increased in length by 0.11 (65.3%) and 0.14 (38.6%) mm less than eyes wearing control soft lenses at 6 and 12 months, respectively (p < 0.05 at both time points). The principal control of axial elongation occurred during the first 6 months. Spherical equivalent cycloplegic autorefraction change from baseline was significantly less in the test cohort than the control cohort by 0.21D (54.0%) at 6 months (p < 0.05) but not at 12 months (0.14D, p > 0.05). Lens type was not overall a significant factor affecting refractive error change (p = 0.0677). After ceasing treatment, neither the rate of axial elongation nor change in SECAR was significantly different between the initial two cohorts. The soft contact lens with +SA slowed axial growth of the eye, although this did not translate into a sustained statistically significant effect on SECAR. The majority of the treatment effect occurred in the initial 6 months of wear. No evidence of rebound effect was observed after ceasing treatment.