Role of corneal epithelial thickness mapping in the evaluation of keratoconus

PurposeTo investigate the corneal epithelial thickness profiles in patients with a confirmed diagnosis of stable and progressive keratoconus.SettingStudio Italiano di Oftalmologia, Rome, Italy.DesignObservational study.Methods86 patients with either stable (n = 52) or progressive (n = 34) keratoconus and 182 healthy controls were enrolled in the study. Disease progression was confirmed by repeated corneal topographies over 1 year follow-up before inclusion in the study. All subjects had full corneal and epithelial thickness mapping taken by spectral domain optical coherence tomography (SD-OCT). The full corneal mapping was investigated by evaluating the central corneal thickness, the thinnest point, the superonasal-inferotemporal thickness difference and the minimum-median thickness difference. The epithelial mapping was investigated by assessing the 2 mm central thickness, the inferior paracentral (2–5 mm) thickness, and the minimum-maximum thickness difference.ResultsNo significant differences in full corneal mapping were found between stable and progressive keratoconic eyes. Of note, the inferior paracentral region of the corneal epithelium was significantly thinner in progressive (50 ± 3 μm) than stable (53 ± 4 μm) keratoconus (P < 0.001).ConclusionsThe SD-OCT corneal epithelial mapping was valuable for detecting local thickness changes in eyes with keratoconus. Monitoring the corneal epithelial changes across the inferior area in patients with keratoconus could be worthy for assessing disease progression.     

Evaluation of the tear clearance rate by dacryoscintigraphy in patients with obstructive meibomian gland dysfunction

PurposeTo measure tear clearance values in patients with meibomian gland dysfunction (MGD) with a dynamic nuclear medicine method, namely, dacryoscintigraphy (DSCI).MethodsTwenty-four MGD patients and 24 healthy volunteers were examined. During DSCI one drop of a solution with 100 MBq/mL^99mTc sodium pertechnetate was instilled with a micropipette into the lacrimal lake of both eyes. Measurements were performed according to a dynamic data acquisition protocol, which resulted in summed DSCI images. Data were also evaluated separately in special regions of interest (ROI), and consecutive time activity curves were created. Tear clearance (T½) values were calculated based on the activity curves. In addition, tear osmolarity measurements, tear breakup time (tBUT), and Schirmer I (ST_I) tests were performed prior to DSCI examination.ResultsThe T½ values were 29.91 ± 11.61 min in MGD patients and 6.26 ± 1.5 min in healthy controls. Tear osmolarity parameters were 308 ± 9.41 mOsm/L and 288.9 ± 6.4 mOsm/L, tBUT values were 5.54 ± 2.73 s and 11.4 ± 2.7 s, while the ST_I test values were 6.17 ± 2.78 mm and 13.58 ± 3.8 mm, respectively. The differences were significant (p < 0.01) in all cases.ConclusionsAlthough the MGD patients’ lacrimal drainage systems were patent their tear clearance values were significantly higher than those of healthy volunteers, which may be caused by decreased drainage of tears from the eyes towards the nasal cavity. The understanding of new features regarding the altered physico-chemical characteristics of MGD tears has been augmented by the results of this study.     

Binding of Iron by Cellulose, Lignin, Sodium Phytate and Beta-Glucan, Alone and in Combination, Under Simulated Gastrointestinal pH Conditions

Cellulose (Ce), Lignin (L), Na phytate (P) and beta-glucan (G), alone, and in combination, were evaluated as to their effect on iron profiles in model systems containing FeSO₄• 7H₂O under simulated gastrointestinal pH conditions. Both cellulose and lignin alone, were found to bind a high percentage of the iron in an insoluble form at pH 5.7±0.4 and pH 6.6±0.1, but less at pH 2.0±0.1. However, in the presence of other model components, cellulose unlike lignin had a minimal effect on total binding at all pH levels. Na phytate, alone, formed soluble complexes at all pH levels and when added to lignin led to the solubiization of some of the iron bound to lignin. Beta-glucan formed soluble iron complexes, which appeared to have a low binding strength with iron.     

Corneal surface wettability and tear film stability before and after scleral lens wear

PurposeThe aim of this study was to evaluate the anterior surface of scleral contact lens and ocular surface wettability before and after one-month of scleral lens wear in patients with keratoconus.MethodsForty-nine patients with keratoconus (36.26 ± 9.03 years) were recruited. The sample was divided into two groups: patients with intrastromal corneal ring (KCICRS group) and patients without ICRS (KC group). TFSQ, Schirmer I test, Ocular Surface Disease Index (OSDI questionnaire), tear break-up time (TBUT) and corneal staining were evaluated in two different visits: Baseline (before lens wear) and one-month visit (10 min after lens removal). Visual Analog Scale (VAS questionnaire) was filled in just after inserting the lenses and just before removing them. TFSQ mean and inferior were evaluated over the contact lens surface at the moment of inserting the lens (baseline visit) and after 8 h of lens wear (one-month visit).ResultsAnterior corneal surface TFSQ values increased in all groups after scleral lens wear (p < 0.05). However, there were no statistical differences found at the moment of inserting or after 8 h of lens wear on previous contact lens surface TFSQ (p > 0.05). No changes were found in tear volume for total and in KC and KCICRS groups (p > 0.05). For all groups, there was a statistical decrease of TBUT (p < 0.05). In addition, OSDI score, corneal staining and VAS score improved after scleral lens wear from baseline in total and in both KC and KCICRS groups (p < 0.05).ConclusionThe scleral contact lens surface keeps its wettability after one-month of wear. However, the wettability of the ocular surface is worse after contact lens wearing.     

Preparation,characterization, bioavailability in vitro and in vivo of tea polysaccharides–iron complex

The task of this study was to prepare a complex of tea polysaccharides (TPS) with ferric iron and research its bioavailability in vitro and in vivo. Optimum condition for preparing tea polysaccharides–iron complex (TPIC) was as follows: TPS and FeCl₃ with a weight ratio of 1:2.4, reacted in a water bath at 60 °C for 3 h, generating an iron content for TPIC of 14.60 %. The digestion in vitro experiment showed that availability of TPIC was sufficient. Then, iron bioavailability in vivo of TPIC was evaluated by the rat hemoglobin-repletion bioassay with ferrous sulfate (FeSO₄) as the positive control. Results indicated that at the end of 21 days’ iron regeneration phase, the values of hemoglobin (Hb) concentration, free erythrocyte protoporphyrin (FEP), serum iron (SI) concentration, and mean cell hemoglobin (MCHC) of rats supplemented with FeSO₄ and TPIC increased quickly to those of normal ones. If the bioavailability of FeSO₄ was given 100 % with Hb concentration, SI concentration and MCHC as the evaluation index, respectively, bioavailability of TPIC were in the range of 101.85–116 %. These results demonstrate that TPIC is a good iron supplement source for increasing uptake and bioavailability in the body.     

Novel liposome-based and in situ gelling artificial tear formulation for dry eye disease treatment

Purpose

Artificial tears are widely used in the treatment of dry eye disease, although current formulations do not closely resemble natural tears. The purpose of this study was the design and characterization of a novel in situ gelling artificial tear formulation, containing both lipid and aqueous components, in order to resemble natural tears and replenish the tear film.

Bioavailability of Iron Produced by the Corrosion of Steel in Apples

The bioavailability of iron formed by the corrosion of low-carbon steel (99% Fe) in contact with Red Delicious apples was measured in a rat model using a depletion-repletion experiment. The percentage of ingested iron converted to hemoglobin iron (Conversion Efficiency) was 74, 57, and 56%, respectively, for daily doses of 110, 190, and 285 μg of this iron. (Conversion Efficiency for FeSO₄ was 46-50%). When compared with FeSO₄= 100, the relative biological value of this iron was found to range from 93–153. Ingestion of one Red Delicious apple that has been exposed to eight large iron nails for 24 hr could provide 10–15 mg iron having good bioavailability.     

Differences between tears of contact lens wearers studied by photon correlation spectroscopy

PurposeThe purpose was to evaluate if there are differences between tears of contact lens (CL) wearers of different materials detectable by measuring the hydrodynamic diameter of tear components through photon correlation spectroscopy (PCS).MethodsTears of 59 CL wearers and tears of 39 non-wearers were collected by glass capillary. Wearers were divided into groups depending on the CL material: (i) hydrogels of II FDA group (H-II, 15 subjects), (ii) hydrogels of IV FDA group (H-IV, 13 subjects), (iii) silicone hydrogels (SH, 31 subjects). PCS analyses were performed at 25 °C on samples diluted with deionized water with tear concentration (10 ± 2)% ^V/_W to obtain, for each subject, the average hydrodynamic diameter (d_H,avg) of tear components by analyzing intensity fluctuations in time of scattered light.ResultsMeans of d_H,avg calculated on each group were found, on increasing order, to be 256 nm (std dev 18 nm) for non-wearers, 297 nm (std dev 45 nm) for H-II, 360 nm (std dev 76 nm) for SH, and 391 nm (std dev 85 nm) for H-IV with statistical differences between each group of wearers compared to non-wearers and between groups of wearers except between SH and H-IV.ConclusionsPCS reveals the differences between tears of CL wearers of different materials, not only between tears of wearers and non-wearers.     

Zeta potential of tear samples: A tool to explore the effects of wear of contact lenses

PurposeThe aim was to develop a method to assess the electrostatic properties of human tear samples, and to evaluate their modifications induced by the wear of contact lenses (CLs).MethodThe barrier method was developed for the measurement of the isoelectric point (IEP) on relatively small quantities. The method was applied to compare three groups: tears (T_NW) of non-wearers, tears (T_{W_etaf}) of regular wearers of etafilcon A CLs, and tears (T_{W_omaf}) of regular wearers of omafilcon A CLs. Zeta potential (ζ) as a function of pH was measured by a Zetasizer Nano ZS90 (Malvern Instruments) on 40%-diluted samples, obtained by mixing 57 μL of tears of different subjects of the same group with 85 μL of HCl aqueous solution. IEP was deduced as the pH at which ζ is zero, i.e. the net electric charge on tear constituents being neutralized.ResultsWithin an error of about 0.05, IEPs were found to be 2.90 (T_NW), 2.80 (T_{W_omaf}), and 3.16 (T_{W_etaf}). On average, a lower H⁺ concentration is needed to neutralize the surface charge of the tear components of etafilcon A wearers, compared to both T_NW and T_{W_omaf}.ConclusionIEP measurements on tear samples of wearers of different types of CLs are proposed in order to enhance the knowledge on the modifications of the profile of charged species in tears. The T_{W_etaf} results, compared to those of the other groups, are compatible with an increase, due to the wear of etafilcon A CLs, of the relative concentration of high-IEP proteins.     

Antioxidant and Antihemolytic Activities of Ethanolic Extract of Flowers,Leaves, and Stems of Hyssopus officinalis L. Var. angustifolius

In this study, antioxidant and antihemolytic activities of ethanolic extract of flowers, leaves, and stems of Hyssopus officinalis L. Var. angustifolius were investigated employing different in vitro assay systems. Extracts showed good antioxidant activity. IC₅₀ for 1,1-diphenyl-2-picryl hydrazyl radical-scavenging activity were 148.8 ± 4.31 μg mL^?1 for flowers, 79.9 ± 2.63 μg mL^?1 for stems, and 208.2 ± 6.45 μg mL^?1 for leaves. All extracts showed moderate iron (II) chelating ability. Extracts exhibited good antioxidant activity in the hemoglobin-induced linoleic acid model and also they were capable of scavenging hydrogen peroxide in a concentration dependent manner. Extracts showed good antihemolytic activity againts hydrogen peroxide-induced hemolysis (IC₅₀ were 48.51 ± 2.27 μg mL^?1 for flowers, 19.47 ± 0.73 μg mL^?1 for leaves, and 63.1 ± 2.65 μg mL^?1 for stems). The total amount of phenolic compounds in the extracts was determined as gallic acid equivalents and total flavonoid content was calculated as quercetin equivalents from a calibration curve.     

Optimizing correction of coma aberration in keratoconus with a novel soft contact lens

PurposeTo report on a second-generation prototype contact lens (modified lens) with enhanced optics to correct coma aberration and compare its performance with that of the prototype contact lens (conventional lens) used to optimise correction of coma aberration in keratoconus (KC).MethodsBoth lenses were designed as a set of standardised soft contact lenses (SCLs) with asymmetric powers along the posterior surface. The modified lens differs from the conventional lens in that the optical zone is decentred superiorly by 0.7 mm. The on-eye performance was compared between the SCLs and no-lens wearing in terms of manifest refraction, corrected distance visual acuity (CDVA), ocular aberrations, subjective quality of vision, and on-eye lens position relative to the pupil.ResultsThirty-four KC eyes were included. SCLs significantly decreased coma aberration compared to no-lens wear (none, 0.68 ± 0.27 μm; conventional lens, 0.37 ± 0.28 μm; modified lens, 0.19 ± 0.15 μm; P < 0.001), with the reduction in coma aberration being significantly greater with the modified lens than with the conventional lens (P = 0.018). No significant difference in manifest refraction or CDVA was found among the three conditions. Quality of vision was significantly better with the modified lens than with no SCL wear (P < 0.05) but no differences were found between the SCLs. The on-eye optical center position relative to the pupil was closer to the pupil centre using the modified lens than the conventional lens (P < 0.001).ConclusionOptimisation of the location of the optical zone in a standardised asymmetric SCL improves correction of coma aberrations and on-eye optical centration.     

Study on iron availability from prepared soybean sprouts using an iron-deficient rat model

During soya seeds germination in FeSO₄ solutions their phytoferritin content is multiplied. Prepared soybean sprouts have been proposed as a safe and easily available source of iron supplementation. The preparation was compared with FeSO₄ and ferritin isolates, using rats with induced iron deficiency anaemia. After the end of the 2-week supplementation experiment, it was observed that no statistically significant differences in haemoglobin concentration, mean corpuscular volume, mean corpuscular haemoglobin, and mean corpuscular haemoglobin concentration existed between those animals supplemented with sprouts enriched in ferritin, ferritin isolate and FeSO₄ and healthy animals forming the control group. Moreover, the examined preparation had a beneficial influence on the recreation of ferritin reserves in both the liver and the blood serum, and also did not induce negative alterations in general growth parameters of animals. Use of an easily obtainable ferritin iron source may be a profitable alternative in supplementation due to its wide availability and food preservative properties.     

Effects of the rigid gas permeable contact lense use on tear and ocular surface among keratoconus patients

Purpose

To investigate changes in tear and ocular surface of patients with keratoconus using rigid gas permeable contact lenses (RGPCL) and compare them against keratoconus patients who were not using lenses as well as a control group of healthy subjects.

Correlation between long-term use of rigid gas permeable contact lenses and endothelial morphometric changes in keratoconus patients

PurposeThis study was conducted to evaluate the effects of long-term use of rigid gas-permeable (RGP) contact lenses on corneal endothelium in keratoconus (KC) patients using non-contact specular microscopy. In addition, the correlation between wearing duration of RGP lenses (years & hours /d) and endothelial morphometric changes in KC patients was performed. This may provide more useful data for clinical application of RGP contact lens.Study designThis study was a prospective, observational, comparative, hospital based, nonrandomized, cross-sectional, and quantitative study.Subjects and methodsThe study included 40 eyes of non-wearer contact lens KC patients (group 1) and 38 KC eyes with a long history of Rose K2 RGP contact lens wearing (group 2). The corneal endothelial morphology such as endothelial cell density (ECD); coefficient of variation of cell area (CV); percentage of hexagonal cells (HEX); and central corneal thickness (CCT) were evaluated in all patients using SP3000P Specular Microscope.ResultsThe study included 40 eyes of non-wearer contact lens KC patients (20 mild KC eyes and 20 moderate KC eyes) and 38 KC eyes with a long history of RGP contact lens wearing (18 mild KC eyes and 20 moderate KC eyes). The mean duration of RGP lenses wearing was 5.67 ± 3.481 years & 12.11 ± 2.698 h/d in mild KC eyes and 7.15 ± 5.294 years &13.65 ± 2.889 h/d in moderate KC eyes. Wearing duration in hours in mild KC eyes showed a significant moderate negative correlation with ECD (r = ?0.529, p = 0.024) and a moderate positive correlation with CV (r = 0.565, p = 0.015). In addition, wearing duration in years in moderate KC eyes showed a significant moderate negative correlation with ECD (r = ?0.465, p = 0.039) and moderate positive correlation with CV (r = 0.627, p = 0.003). However, wearing duration in hours in moderate KC eyes showed a significant moderate negative correlation with HEX only (r = ?0.490, p = 0.028). This study reported significant corneal thinning in contact lens wearer KC eyes in contrast to non-wearer KC eyes.ConclusionThis study documented a significant correlation between a long-term use of Rose K2 RGP using the three-point touch and corneal endothelial morphometric changes in KC patients. In addition, the current study confirmed a significant corneal thinning in RGP contact lens wearer compared to non-contact lens wearer KC patients. Further studies are recommended to evaluate the association between different RGP lens materials with different oxygen permeability transmissibility; different lens design types; different fitting methods; the duration of contact lens wear and the endothelial morphometric changes in KC patients.     

Chemical and Cellular Antioxidant Activities of Chicken Breast Muscle Subjected to Various Thermal Treatments Followed by Simulated Gastrointestinal Digestion

The effect of thermal treatments on chemical and cellular antioxidant activities of chicken breasts subjected to in vitro gastrointestinal digestion was investigated. Breast of Korat crossbred chicken (KC) and commercial broiler (BR) were cooked under various conditions, namely heating at 70 °C for 30 min (H‐0.5) and 24 h (H‐24), autoclaving (AC) at 121°C for 15 min (AC‐15) and 60 min (AC‐60). Protein digestibility decreased upon the extreme thermal treatment of AC‐60. The H‐0.5 improved metal chelating activity of KC digesta, FRAP, and anti‐liposome oxidation of BR digesta. Digesta of BR/H‐0.5 and KC/AC‐15 at 50 μg/mL exhibited the highest cytoprotective effect against tert‐butyl hydroperoxide (TBHP)‐induced oxidative damage of HepG2 cells. In addition, the KC/AC‐15 digesta at a concentration as low as 12.5 μg/mL inhibited intracellular TBHP‐induced reactive oxyfen species (ROS) production (P < 0.05). Thus, the digesta of KC breasts subjected to AC‐15 provides not only nutritional value but also antioxidant activity at the cellular level.     

Posterior cornea and thickness changes after scleral lens wear in keratoconus patients

PurposeTo evaluate the changes in the corneal thickness, anterior chamber depth and posterior corneal curvature and aberrations after scleral lens wear in keratoconus patients with and without intrastromal corneal ring segments (ICRS).MethodsTwenty-six keratoconus subjects (36.95 ± 8.95 years) were evaluated after 8 h of scleral lens wear. The subjects were divided into two groups: those with ICRS (ICRS group) and without ICRS (KC group). The study variables evaluated before and immediately after scleral lens wear included corneal thickness evaluated in different quadrants, posterior corneal curvature at 2, 4, 6 and 8 mm of corneal diameter, posterior corneal aberrations for 4, 6 and 8 mm of pupil size and anterior chamber depth.ResultsThere was a statistically significant corneal thinning (p < 0.05) in the inferior region of the KC group and in the superior region of the ICRS group. No change (p > 0.05) in the anterior chamber depth was found. The KC group showed a steepening (p < 0.05) in the temporal quadrant and a flattening that mainly affected to the superior-nasal quadrant. The ICRS group showed a steepening (p < 0.05) that mainly affected to the superior-nasal quadrant. Regarding posterior corneal aberrations, only changes (p < 0.05) in Z4 for 8 mm and Z8 for 4 mm were found in the KC group.ConclusionsShort-term scleral lens wear showed a thinning of the cornea and changes in the posterior corneal curvature affects different regions in keratoconus patients with and without ICRS.     

Antioxidant and antigenotoxic effect of dairy products supplemented with red ginseng extract

The purpose of this study was to evaluate the antioxidant and antigenotoxic effect of dairy products milk (M) and yogurt (Y) after the addition of 2% red ginseng extract to milk (RM) and to yogurt (RY). Total phenolic content, total flavonoid content, 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, oxygen radical absorbance capacity, and total radical trapping antioxidant potential were determined in the samples. Furthermore, antigenotoxic effect of samples was measured, using comet assay in human leukocytes. Total phenolic content and total flavonoid content of RM [38.3 ± 0.8 mg of gallic acid equivalents (GAE)/100 g, 23.6 ± 0.1 mg of quercetin equivalents (QE)/100 g] and RY (41.1 ± 0.9 mg of GAE/100 g, 18.7 ± 0.1 mg of QE/100 g), respectively, were higher than those of M (6.31 ± 0.2 mg of GAE/100 g, 10.4 ± 0.1 mg of QE/100 g) and Y (8.1 ± 0.9 mg of GAE/100 g, 8.4 ± 0.2 mg of QE/100 g), respectively. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and oxygen radical absorbance capacity values increased significantly after the addition of 2% red ginseng in both. Additionally, the total radical trapping antioxidant potential in RM (787.7 ± 7.0 μg/mL) was lower than in M (2074.0 ± 28.4 μg/mL). The H₂O₂-induced DNA damage in RY (0.1 ± 0.0 mg/mL) was less than the damage in Y (0.4 ± 0.0 mg/mL), but we found no significant difference between M and RM. This study indicates that supplementation with red ginseng can fortify the antioxidant and antigenotoxic effects of dairy products effectively.     

Antioxidant activities and inhibitory effects of dietary plants against sodium nitroprusside induced lipid peroxidation in the mouse brain and liver

The antioxidant properties of aqueous extracts of 6 medicinal plants, Phyllanthus emblica, Terminalia chebula (black and yellow), Terminalia arjuna, Balsamodendron Mukul, and Alium sativum against lipid peroxidation in mouse tissues were investigated. Extracts showed inhibition against thiobarbituric acid reactive species (TBARS) induced by pro-oxidant (5 μM sodium nitroprusside) in the mouse brain and liver. Extracts displayed high free radical scavenging activities against DPPH (IC₅₀, 23.23±1.2 μg/mL, P. emblica), 20.24±0.9 μg/mL (T. chebula yellow), 17.33±1.1 μg/mL (T. chebula black), 19.44±0.45 μg/mL (T. arjuna), 56.59±2.1 μg/mL (Balsamo-dendron Mukul), and higher than 200 μg/mL (A. sativum). Higher antioxidant and inhibitory effects of T. chebula black are attributed to a higher phenolic content, Fe(II) chelating ability, reducing ability, nitric oxide radical scavenging, and free radical scavenging activity. Oxidative stress in the brain and liver could potentially be managed/prevented by dietary intake of these plants.     

Effects of a semi-scleral contact lens on refraction and higher order aberrations

PurposeTo investigate effects of Rose K2 XL semi-scleral contact lenses (Menicon Co.) on visual acuity and higher-order aberrations in eyes with irregular corneas. Methods: One hundred and twelve eyes of 84 patients fitted with Rose K2 XL lenses were analysed. Participants were in 4 clinical groups: keratoconus, intra-corneal ring segments, radial keratotomy, and penetrating keratoplasty. Corrected distance visual acuity and ocular aberrations were determined before lens wear and 60 min into lens wear. The i-Trace aberrometer was used to determine aberrations at 4.5 mm pupil size.ResultsThere were 55, 22, 19 and 16 eyes in keratoconus, intra-corneal ring segments, radial keratotomy and penetrating keratoplasty groups, respectively. Before lens wear, eyes had poor corrected distance vision acuity (mean and standard deviation +0.55 ± 0.33 logMAR), high negative spherical equivalent refraction (−6.4 ± 3.7 D), high cylindrical errors (4.5 ± 2.2 D), large higher-order root-mean-squared (HO-RMS) aberration (1.5 ± 1.3 μm) and large higher-order aberration components. Cylinder was particular high for the penetrating keratoplasty group (mean 5.9 ± 2.5 D), root-mean-squared third-order coma was lowest for the radial keratotomy group (0.7 ± 1.0 μm), and fourth-order spherical aberration was highly negative for the intra-corneal ring segment group (co-efficient –0.4 ± 0.7 μm). With lens wear, the values changed considerably. Corrected distance visual acuity improved by 0.51 ± 0.31 logMAR, cylinder decreased by 3.6 ± 2.1 D, HO-RMS aberration reduced by 1.1 ± 1.2 μm, and higher-order aberration components decreased considerably. Magnitudes of group changes reflected the magnitudes before lens wear.ConclusionsRose K2 XL semi-scleral contact lenses were effective in improving vision and reducing ocular aberrations for eyes with irregular corneas.     

Hydrogen-peroxide and silicone-hydrogel contact lenses: Worsening of external eye condition and tear film instability

Purpose

The aim is discussing the origins of worsening of external eye condition (EEC) and of tear film (TF) instability after wear of silicone-hydrogel contact lenses (CLs) with hydrogen-peroxide (H₂O₂) care system.