Fluorescein staining and physiological state of corneal epithelial cells

PurposeTo evaluate the physiological status of corneal epithelial cells exhibiting fluorescein staining.MethodsFluorescein staining properties of corneal epithelial cells under normal and stressed conditions were studied using cell-culture (human corneal limbal epithelial cells – HCLE) and organ-culture (rabbit) models. Stress stimuli comprised exposure to hypotonicity, hypertonicity, preservatives, scratch, and alkaline wounding. In addition to fluorescein, cells were stained with Hoechst-33342 (HO), Propidium-iodide (PI), and Annexin-V (AN-V) to identify live, dead and apoptotic cells. Clinical-slit-lamp and fluorescence confocal-microscopic (FCM) observations were performed. FCM images were quantified for fluorescence intensity using Image-J software.ResultsHealthy HCLE cells uniformly took up fluorescein to a moderate degree with a mean grey value of 62 ± 24 (mean ± SD) on a scale of 0–256 (no unit). Fluorescence levels similar to those observed prior to stress were associated with healthy cells. Apoptotic cells showed the highest fluorescence (138 ± 38). Dead cells showed minimal fluorescence (23 ± 7) that was similar to the background (20 ± 11, p > 0.05). Observations in whole rabbit eyes were in general agreement with these cell culture findings.ConclusionsThe clinical observation of corneal staining with fluorescein suggests the presence of epithelial cells that are undergoing apoptosis but does not indicate dead cells. Under in vitro or ex vivo conditions, healthy cells took up fluorescein at levels that were lower than those of apoptotic cells and thus, are not likely to be perceived as exhibiting staining during clinical observation. Sodium fluorescein may be considered as a probe for apoptotic epithelial cells.     

Changes in central corneal thickness values after instillation of oxybuprocaine hydrochloride 0.4%

PurposeTo assess the variation in central corneal thickness (CCT) following the instillation of oxybuprocaine hydrochloride (0.4%), in normal subjects.MethodsThis was a randomized, prospective study of CCT measurements (before and after the instillation of topical anaesthesia) obtained with the Topcon SP-3000P noncontact specular microscope, in 60 eyes of thirty subjects. The subjects’ mean age was 20 ± 1 years (mean ± SD). In each subject, one eye was treated with one drop of oxybuprocaine hydrochloride (HCl) and the fellow eye with one drop of normal saline (control). The SP-3000P CCT readings were first obtained before instillation (baseline) and monitored every 30 s after instillation of each eye drop for a period of 10 min.ResultsThe mean baseline CCT for oxybuprocaine was 526 ± 23 μm. Ten minutes after, it was 526 ± 24 μm. In the control, the mean CCT was 526 ± 27 μm, 10 min after it was 526 ± 28 μm. The mean variation in CCT measurement was ?0.7 ± 3.1 (5.5 to ?6.8 μm, 95% CI) for oxybuprocaine and ?0.6 ± 4.1 μm (7.5 and ?8.6 μm, 95% CI) for the fellow eyes (P > 0.05). There was no significant variation among the 20 CCT columns for either oxybuprocaine or the control group (P > 0.05 for both).ConclusionsOne drop of topical oxybuprocaine 0.4% did not cause a significant change in CCT at up to 10 min following instillation. However, higher differences were observed at 2.30 min and 4.30 min after instillation.     

Pain,wound healing and refractive comparison of mechanical and transepithelial debridement in photorefractive keratectomy for myopia: Results of 1 year follow-up

PurposeTo compare the efficacy, safety and postoperative pain of mechanical versus transepithelial photorefractive keratectomy (PRK) techniques.SettingCornea and refractive surgery subspecialty.DesignProspective clinical trial.MethodsThis prospective comparative study included 84 eyes of 42 patients with myopia who received mechanical PRK (m-PRK) in 1 eye and transepithelial PRK (t-PRK) in the contralateral eye. The mean patient age was 28.5 ± 6.3 years (range 20–46 years). Postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refractions, postoperative epithelial healing time, surgical time, postoperative pain rating and corneal haze were recorded.ResultsAt week 1, statistically the UDVA was significantly better in the t-PRK eyes; however, at 3 months, similar refractive stability was achieved in both groups. The mean spherical equivalent (SE) decreased from −2.44 ± 1.00 D (m-PRK eyes) and −2.88 ± 1.24 D (t-PRK eyes) at baseline to −0.19 ± 0.38 D and −0.30 ± 0.40 D, respectively, after 1 year. Surgical time was 98.6 ± 9.8 s in m-PRK eyes and 58.0 ± 6.4 s in t-PRK eyes. On postoperative days 1 and 3, using the global assessment rating, 81% of mPRK eyes that had pain, reported more pain than that reported for the tPRK eyes. In addition, m-PRK treated eyes demonstrated higher mean pain scores based on the 11-point numerical rating scale and Visual Analogue Scale (VAS). The mean time to complete epithelial healing was 2.19 ± 0.39 days (t-PRK) and 3.76 ± 0.43 days (m-PRK).Conclusiont-PRK for mild-to-moderate myopia was more comfortable than conventional m-PRK; patients had less pain, and faster healing time.     

Viscoelastic-plastic behavior of single tomato mesocarp cells in high speed compression-holding tests

The micromechanics of isolated tomato fruit cells were investigated by microcompression-holding. Covering the cells with deionized water after isolation caused no significant volume changes, suggesting that cells suspended in water for compression testing were representative of those in the original tissue. The viscoelastic-plastic behavior of such cells was characterized by compression at 4900 ± 200 μm s^− 1, then holding. Although the cells were generally not spherical initially and some cell deformation appeared to be local, the force-time data were fitted by the Hertz–Maxwell model for relaxation of viscoelastic spheres. The force at 15% deformation, instantaneous and equilibrium elastic moduli, yield strength, and first and second relaxation times were 2.5 ± 0.6 mN, 0.6 ± 0.3 MPa, 0.22 ± 0.08 MPa, 0.03 ± 0.01 MPa, 0.48 ± 0.05 s, and 0.033 ± 0.004 s, respectively. These parameters showed little sensitivity to several reasonable definitions of cell size nor to changes in the (assumed) Poisson's ratio.Industrial relevanceFresh fruit is very susceptible to damage during industrial handling (e.g. mechanical harvesting, packaging and transport). Mechanical damage to fruit, manifested at the macro scale, is caused ultimately by failure of cells at the micro scale. Viscoelastic-plastic characterization of single cells isolated from tissue is vital to macro-scale modeling, simulation and prediction of mechanical damage to fruits. The method might be extended to single cells of other fruits.     

Fluorescence characteristics of sodium fluorescein–rose bengal ophthalmic solution mixtures

PurposeTo assess fluorescence emission properties of sodium fluorescein–rose bengal mixtures in buffered aqueous solution.MethodsSolutions of sodium fluorescein (NaFl) or rose bengal (RB) or mixtures of these two chemicals were prepared over a range of dilutions in 1% NaCl with 10 mM phosphate buffer to give a pH of 7.5 at room temperature. Absorbance and fluorescence spectra were recorded in 10 mm path length cuvettes.ResultsThe fluorescence emission from NaFl extends between 480 and nearly 600 nm, a spectral range that is also covered by the absorbance of RB (between 500 and 580 nm). With very dilute solutions of NaFl (less than 0.002%), an apparent total quenching of its fluorescence can occur in the presence of 0.01% RB, with a proportionate decrease at lower concentrations of RB.ConclusionsThe presence of RB in an aqueous solution of NaFl at physiological pH appears to act in a similar way to a barrier filter, resulting in the quenching of the measurable fluorescence from NaFl. It remains to be established how substantial or significant such an effect might be if a mixture of NaFl and RB as used as part of the examination of the external eye.     

Evaluation of anterior chamber angle under dark and light conditions in angle closure glaucoma: An anterior segment OCT study

AimTo evaluate changes of nasal and temporal anterior chamber angle (ACA) in subjects with angle closure glaucoma using Spectralis AS-OCT (SAS-OCT) under dark and light conditions.MethodsBased on dark-room gonioscopy, 24 subjects with open angles and 86 with narrow angles participated in this study. The nasal and temporal angle opening distance at 500 μm anterior to the scleral spur (AOD500), nasal and temporal ACA were measured using SAS-OCT in light and dark conditions.ResultIn 2 groups, ACA and AOD500 in nasal and temporal quadrants were significantly greater in light compared to dark (all with p = 0.000). The AOD500 and ACA were significantly higher in nasal than temporal in measured conditions for 2 groups except the ACA and AOD500 of normal group measured in light. The difference between nasal and temporal in dark (29.07 ± 65.71 μm for AOD500 and 5.7 ± 4.07° for ACA) was greater than light (24.86 ± 79.85 μm for AOD500 and 2.09 ± 7.21° for ACA) condition. But the difference was only significant for ACA (p = 0.000). The correlation analysis showed a negative correlation between AOD500 and pupil diameter in temporal and nasal quadrants (both with p = 0.000). While temporal AOD500 difference correlated with spherical equivalent, temporal and asal gonioscopy, nasal AOD correlated with IOP, temporal and nasal gonioscopy.ConclusionsClinically important changes in ACA structure could be detected with SAS-OCT in nasal and temporal quadrants under different illumination intensity. The results could help in improvement of examination condition for better and more accurate assessment of individuals with angle closure glaucoma.     

Rose bengal staining as an assessment of ocular surface damage and recovery in dry eye disease—A review

PurposeTo review the use of ophthalmic rose bengal to assess the ocular surface, especially considering the grading scales used.MethodsA literature search was undertaken to identify reports where either rose bengal or lissamine green had been used as a ‘vital’ stain, with a special interest in identifying studies that provided data before and after treatment for dry eye and also considered the mechanism of action of these two chemicals.ResultsBetween 1985 and 2006, numerous clinical studies used a consistent grading scheme (that attributed to Van Bijsterveld) to assess the outcome of artificial tear treatments on dry eye patients. With such consistency, including the adoption of a treatment period of 1 month, comparisons can be made to indicate the efficacy of rose bengal staining to assess reduction in ocular surface desiccation. However, in the following years, several alternative grading schemes have been used for both rose bengal and lissamine green and assessment periods have been variable so making inter-study comparisons considerably more difficult to undertake. An attribute of rose bengal appears to be its ability to stain the nuclei of cells, but whether this also occurs for lissamine green is unclear.ConclusionsOphthalmic rose bengal has been successfully adopted for use to assess the ocular surface over many years as a vital stain. More research is needed to assess whether lissamine green ocular surface staining can simply be substituted for rose bengal in evaluation of dry eye treatments.     

Antioxidant packaging with encapsulated green tea for fresh minced meat

A novel approach to incorporate green tea extract into polyethylene by extrusion technology has been studied. Green tea entrapped by inorganic capsules was incorporated into melted material and extruded without compromising its quality. The shelf-life of fresh meat from two types of active packaging was significantly extended for 3 days compared to blank samples. Significant difference was observed after 9th day of study in case of results of CIE L*a*b*, MetMb and organoleptic assay. Migration study of antioxidants from the materials was also performed by UHPLC-MS/TQ using food simulants. Amount of migrated catechins was in the range between 6.3 ± 3.3 and 228.4 ± 15.2 μg/kg (ratio 6:1). Regression coefficients (R) between 0.9925 and 0.9989 were obtained. Minimum LOD (0.001 μg/g) and LOQ (0.004 μg/g) were obtained for epicatechin gallate and catechin gallate while maximum LOD (0.057 μg/g) and LOQ (0.191 μg/g) were obtained for catechin.     

Predicting success with silicone-hydrogel contact lenses in new wearers

Purposeto evaluate changes in tear metrics and ocular signs induced by six months of silicone-hydrogel contact lens wear and the difference in baseline characteristics between those who successfully continued in contact lens wear compared to those that did not.MethodsNon-invasive Keratograph, Tearscope and fluorescein tear break-up times (TBUTs), tear meniscus height, bulbar and limbal hyperaemia, lid-parallel conjunctival folds (LIPCOF), phenol red thread, fluorescein and lissamine-green staining, and lid wiper epitheliopathy were measured on 60 new contact lens wearers fitted with monthly silicone-hydrogels (average age 36 ± 14 years, 40 females). Symptoms were evaluated by the Ocular Surface Disease Index (OSDI). After six months full time contact lens wear the above metrics were re-measured on those patients still in contact lens wear (n = 33). The initial measurements were also compared between the group still wearing lenses after six months and those who had ceased lens wear (n = 27).ResultsThere were significant changes in tear meniscus height (p = 0.031), bulbar hyperaemia (p = 0.011), fluorescein TBUT (p = 0.027), corneal (p = 0.007) and conjunctival (p = 0.009) staining, LIPCOF (p = 0.011) and lid wiper epitheliopathy (p = 0.002) after six months of silicone-hydrogel wear. Successful wearers had a higher non-invasive (17.0 ± 8.2 s vs 12.0 ± 5.6 s; p = 0.001) and fluorescein (10.7 ± 6.4 s vs 7.5 ± 4.7 s; p = 0.001) TBUT than drop-outs, although OSDI (cut-off 4.2) was also a strong predictor of success.ConclusionSilicone-hydrogel lenses induced significant changes in the tear film and ocular surface as well as lid margin staining. Wettability of the ocular surface is the main factor affecting contact lens drop-out.     

Effect of ohmic heating on texture,microbial load,and cadmium and lead content of Chilean blue mussel (Mytilus chilensis)

The effect of ohmic heating (OH) on the texture, microbial load, and cadmium (Cd) and lead (Pb) content was evaluated in Chilean blue mussel (Mytilus chilensis) at shucking and subsequent canning. Mussel samples were processed by OH and blanching (BLAN) at 50 ± 1 °C, 70 ± 1 °C and 90 ± 1 °C for shucking and then canning at 115 °C for 20 min. The Cd and Pb content in fresh mussels was 2.47 ± 0.18 μg g^− 1 and 5.26 ± 0.55 μg g^− 1 dry weight (dw). The greatest reduction in Cd content was reached at 90 ± 1 °C by OH with 1.67 ± 0.06 μg g^− 1 (dw) and 1.69 ± 0.08 μg g^− 1 (dw) by BLAN. At the same temperature, the Pb content was reduced to 4.18 ± 0.24 μg g^− 1 dw for OH and 4.14 ± 0.30 μg g^− 1 dw for BLAN. The cutting strength of fresh samples (21.35 ± 2.44 N) significantly decreased in samples processed by OH (15.65 ± 1.36 N) at 90 ± 1 °C compared with BLAN samples (20.41 ± 3.16 N) at the same temperature. The initial mean count for mesophilic aerobic microorganisms and Enterobacteriaceae was 3.8 log cfu/g and 2.5 log cfu/g, respectively. The mesophilic aerobic microorganism count was reduced by 1.7 logarithmical units, while Enterobacteriaceae counts were reduced to undetectable levels by OH at 90 ± 1 °C.Industrial relevanceHigh temperature short time (HTST) processes rely on rapid convection heat transfer and are thus well suited to liquid foods. But, they are, however, limited in application to particulates since, for particles more than a couple of millimeters thick, the processing time is insufficient for heat to transfer to the center to give sterility. Ohmic heating is an emerging technology and very promising in food industries. It is a thermal process in which heat is generated internally in food and acts as a resistance to the flow of alternating electric current. This type of treatment prevents overheating by producing less deterioration in food components. It is a rapid procedure that allows food to conserve its natural properties; microorganisms and enzymes are also inactivated. The purpose of the present work was to evaluate the effect of Ohmic heating on mechanical properties, microbial load, Cd and Pb content in the opening and subsequent canning of Chilean blue mussel (Mytilus chilensis). This information could be used for the seafood industries in order to improve thermal heating processes in mussels.     

Evaluation of central corneal thickness after cataract surgery,penetrating keratoplasty and long-term soft contact lens wear

PurposeThe aim of this study was to compare central corneal thickness (CCT) between corneas of normal healthy eyes (cNHE), corneas of eyes that had undergone cataract surgery by clear corneal phacoemulsification with implantation of an intracapsular intraocular lens (cIOL), corneal grafts after penetrating keratoplasty (gPK) and corneas of long-term soft contact lens wearers (cCL).MethodsThe study design was a consecutive cross-sectional trial. CCT was measured using rotating Scheimpflug camera (Pentacam, software version 1.16r04) in 80 cNHE, 79 cIOL, 46 gPK and 78 cCL. Analysis of variance (one-way ANOVA) was performed to compare differences of mean values between these four groups. Pearson's or Spearman's correlation coefficient (r) was determined between CCT value and age, follow up time after penetrating keratoplasty (timePK) or contact lens wearing time (timeCL).ResultsMeans of CCT measurements were comparable between cNHE (mean CCT ± standard deviation, 554 ± 36 μm), cIOL (551 ± 40 μm) and gPK (534 ± 52 μm) as determined by one-way ANOVA. Mean CCT values in cCL (537 ± 37 μm) were statistically significantly lower in comparison to cNHE (p = 0.026, 95% CI = 1.43–31.44). There was no linear correlation between age and CCT values of cNHE and cIOL (p = 0.841, r = −0.031 and p = 0.931, r = 0.011, respectively). No linear relationship was determined between CCT values of cCL and timeCL (p = 0.315, r = −0.125). CCT values of gPK did not correlate with timePK (p = 0.738, r = 0.054).ConclusionsThe data reported here indicate that in the same statistical model among CCT values of cNHE, cIOL and gPK only long-term soft contact lenses (CL) wearer have significantly lower CCT measurements.     

Corneal biomechanical properties: Precision and influence on tonometry

PurposeTo assess the precision and reproducibility of the corneal biomechanical parameters, and their relationships with the intraocular pressure (IOP) measured with the Goldmann tonometer and a noncontact tonometer.MethodsReadings for biomechanical properties and for IOP measured with the Goldmann and noncontact tonometers, were taken on one randomly selected eye of 106 normal subjects, on each one of two measurement sessions. Measurements with the ocular response analyzer (ORA) and the noncontact tonometer were randomized, followed by the measurement of central corneal thickness and with the Goldmann tonometer.ResultsRepeatability coefficients for CCT, corneal hysteresis (CH) and corneal resistance factor (CRF) in Session 1 were ±0.01 μm, ±3.05 mmHg and ±2.62 mmHg, respectively. The mean CCT, CH, CRF, Goldmann and noncontact tonometry did not vary significantly between sessions. Reproducibility coefficients for CCT, CH and CRF were ±0.02 μm, ±2.19 mmHg and ±1.97 mmHg, respectively. Univariate regression analysis showed that CCT, CH and CRF significantly (P < 0.0001) correlated with the IOP measured with the Goldmann and noncontact tonometers (and with the differences between tonometers) in Session 1. There were no significant correlations with the differences between tonometers in Session 2. Multivariate analysis revealed a minimal effect of CCT on Goldmann measurements but a significant effect on those of the noncontact tonometer.ConclusionsMeasurement of the biomechanical properties of the cornea, using the ORA, are repeatable and reproducible, affect Goldmann tonometry less than noncontact tonometry, and have a minimal influence on the difference in measured intraocular pressure between tonometers.     

Agreement and reliability in measuring central corneal thickness with a rotating Scheimpflug–Placido system and ultrasound pachymetry

PurposeWe compare the agreement and the reliability in measuring central corneal thickness (CCT) using two different technologies.MethodThe right eyes of 35 healthy individuals who had a negative history of ophthalmic disease, or ocular surgery were examined. The CCT was determined sequentially with a rotating Scheimpflug camera (Sirius; CSO), and an ultrasound pachymeter (P-1; Takagi). For statistical analysis, we used the methods suggested by Bland and Altman.ResultsThe mean values of CCT obtained from Sirius, and ultrasound were 537 ± 28 μm, and 550 ± 35 μm, respectively. There was a high correlation between Sirius and ultrasound (r = 0.92; p < 0.001), but the difference between the two measurements was statistically significant (t = −5.7; p < 0.00001). The precision of Sirius and ultrasound were 9.4 and 15.9 μm; repeatability 13.3 and 22.4 μm, and coefficient of variation 0.9% and 1.5%, respectively. The intraclass correlation coefficient was 0.97 for Sirius and 0.95 for ultrasound.ConclusionsThe average difference between corneal thickness measured with Sirius and ultrasound pachymetry was small but clinically significant. This means that the two instruments cannot be used interchangeably. Sirius showed precision and repeatability almost twice as much as ultrasound pachymetry. Confidence interval of 13.3 μm for Sirius can show variations in corneal thickness with an uncertainty value lower than 2.5% in 95% of cases. The simplicity of use, the possibility to obtain pachymetric maps, and less invasiveness make this instrument potentially useful in contact lens practice.     

Conjunctival UV autofluorescence – Prevalence and risk factors

PurposeAutofluorescence of ultraviolet (UV) light has been shown to occur in localised areas of the bulbar conjunctiva, which map to active cellular changes due to UV and environmental exposure. This study examined the presence of conjunctival UV autofluorescence in eye care practitioners (ECPs) across Europe and the Middle East and its associated risk factors.MethodImages were captured of 307 ECPs right eyes in the Czech Republic, Germany, Greece, Kuwait, Netherlands, Sweden, Switzerland, United Arab Emirates and the United Kingdom using a Nikon D100 camera and dual flash units through UV filters. UV autofluorescence was outlined using ImageJ software and the nasal and temporal area quantified. Subjects were required to complete a questionnaire on their demographics and lifestyle including general exposure to UV and refractive correction.ResultsAverage age of the subjects was 38.5 ± 12.2 years (range 19–68) and 39.7% were male. Sixty-two percent of eyes had some conjunctival damage as indicated by UV autofluorescence. The average area of damage was higher (p = 0.005) nasally (2.95 ± 4.52 mm²) than temporally (2.19 ± 4.17 mm²). The area of UV damage was not related to age (r = 0.03, p = 0.674), gender (p = 0.194), self-reported sun exposure lifestyle (p > 0.05), geographical location (p = 0174), sunglasses use (p > 0.05) or UV-blocking contact lens use (p > 0.05), although it was higher in those wearing contact lenses with minimal UV-blocking and no spectacles (p = 0.015). The area of UV damage was also less nasally in those who wore contact lenses and spectacles compared to those with no refractive correction use (p = 0.011 nasal; p = 0.958 temporal).ConclusionUV conjunctival damage is common even in Europe, Kuwait and UAE, and among ECPs. The area of damage appears to be linked with the use of refractive correction, with greater damage nasally than temporally which may be explained by the peripheral light focusing effect.     

Evaluation of the ocular tolerance of a novel eyelid-warming device used for meibomian gland dysfunction

PurposeObstructive meibomian gland dysfunction (MGD) frequently induces a chronic complaint with various symptoms related to dry eye and discomfort. Previous research indicates a pivotal role for heat therapy for melting the meibum as part of any successful management plan, but delivery of constant temperature during treatment is vital. This study evaluated the performance of a novel device designed to deliver controlled, latent, moist heat to the eyelids and surrounding area.MethodsThe signs, symptoms and ocular temperature of 25 normal subjects (M8, F17; age 29.2 ± 5.7 years) were recorded before and after a 10 min application of the Blephasteam^® device. Ocular temperature (non-invasive ocular thermography; A40 Flir, UK), tear film stability (NIBUT), intra-ocular pressure (IOP), and ocular surface staining and hyperaemia were recorded. Results were checked for normality and compared using paired t-tests.ResultsTemperatures in both eyelids were significantly greater after device application (upper +1.7 ± 0.9 °C; lower +2.1 ± 0.7 °C, p < 0.0005). Bulbar conjunctival hyperaemia significantly decreased after treatment (p < 0.005), but limbal and palpebral hyperaemia remained similar (p = 0.33 and p = 0.11, respectively). Ocular surface staining (p = 0.74) and tear film stability (p = 0.12) were unchanged in this normal cohort, and there was no significant change in IOP (13.8 ± 2.0 mmHg vs 12.9 ± 2.2 mmHg; p = 0.092).ConclusionsThe Blephasteam^® device provides effective levels of warming that would be sufficient to melt meibum, and no adverse ocular responses were recorded in this cohort, indicating that this is a safe device. Interestingly, even in this normal cohort, ocular surface redness appears less after treatment.     

Bitoric rigid gas permeable contact lenses in the optical management of penetrating keratoplasty

PurposeThe purpose of this study was to evaluate the complexity and effectiveness of fitting bitoric rigid gas permeable contact lenses (RGPCLs), compared to spherical RGPCLS, when used in the correction of high amounts of post-penetrating keratoplasty astigmatism.MethodsRecords of post-penetrating keratoplasty (PKP) patients being managed with bitoric RGPCLs were compared to controls (post-PKP patients managed with spherical RGPCLs). Factors that were analyzed included the number of diagnostic RGPCLs used to assess the initial fit, the number of RGPCLs ordered to finalize the fit and the number of total doctor visits to finalize the fit.ResultsFourteen eyes of 14 patients satisfied the study criteria. The average amount of total astigmatism in this study group was 10.0 D ± 5.0 compared to the control group which was 3.3 D ± 2.6. The number of diagnostic RGPCLs used for the study group was 1.2 ± 0.4 compared to 1.0 ± 0.0 for the control group. The mean number of contact lenses ordered to complete the fitting for the study group was 1.9 ± 0.7 compared to the control which was 2.1 ± 0.8. The study group presented for an average of 6.3 ± 1.6 visits whereas the control group presented for 4.9 ± 1.1 visits. Contact lens corrected acuity for the study group was 0.101 ± 0.11 (20/25) compared to the control group 0.08 ± 0.12 (20/24).ConclusionsThe complexity of fitting bitoric RGPCLs was found to be similar to fitting spherical RGPCLs on post-PKP eyes and the visual outcomes were not different.     

Corneal changes following short-term miniscleral contact lens wear

PurposeTo examine the influence of short-term miniscleral contact lens wear on corneal shape, thickness and anterior surface aberrations.MethodsScheimpflug imaging was captured before, immediately following and 3 h after a short period (3 h) of miniscleral contact lens wear for 10 young (mean 27 ± 5 years), healthy participants. Natural diurnal variations were considered by measuring baseline diurnal changes obtained on a separate control day without contact lens wear.ResultsSmall but significant anterior corneal flattening was observed immediately following lens removal (overall mean 0.02 ± 0.03 mm, p < 0.001) which returned to baseline levels 3 h after lens removal. During the 3 h recovery period significant corneal thinning (−13.4 ± 10.5 μm) and posterior surface flattening (0.03 ± 0.02 mm) were also observed (both p < 0.01). The magnitude of posterior corneal flattening during recovery correlated with the amount of corneal thinning (r = 0.69, p = 0.03). Central corneal clearance (maximum tear reservoir depth) was not associated with corneal swelling following lens removal (r = −0.24, p > 0.05). An increase in lower-order corneal astigmatism Z(2,2) was also observed following lens wear (mean −0.144 ± 0.075 μm, p = 0.02).ConclusionsFlattening of the anterior corneal surface was observed immediately following lens wear, while ‘rebound’ thinning and flattening of the posterior surface was evident following the recovery period. Modern miniscleral contact lenses that vault the cornea may slightly influence corneal shape and power but do not induce clinically significant corneal oedema during short-term wear.     

Consumption of highly processed foods: Effects on bioavailability and status of zinc and copper in adolescents

The effects of consuming diets with different Maillard reaction products (MRP) content on zinc and copper bioavailability and status were examined. In a 2-week randomised 2-period crossover trial, 18 male adolescents consumed two diets, named white diet (WD) and brown diet (BD), which were poor and rich in MRP, respectively. A 3-day balance was performed at the end of each period and fasting blood samples were collected. Zinc bioavailability did not vary significantly between the diets (%WD: 21.0 ± 5.0, %BD: 15.1 ± 5.1), but BD consumption increased copper faecal excretion (~ 1.8-fold) and significantly decreased its bioavailability (~ 3.0-fold). Biochemical parameters related to zinc metabolism remained unaltered whereas copper in serum and erythrocytes significantly decreased after consumption of the BD (72.47 ± 2.42 μg/dl and 0.93 ± 0.01 μg/ml in serum and erythrocytes with WD compared to 65.87 ± 3.11 μg/dl and 0.84 ±0.02 μg/ml with BD). The present results suggest that the high presence of MRP in the diet does not affect zinc but negatively affects copper bioavailability. As both minerals are essential trace elements involved in adolescents' growth and development, possible long-term effects of excessive MRP intake during adolescence warrant attention.     

Long term results of Epi-LASIK and LASEK for myopia

PurposeTo evaluate the long term clinical and confocal results of mechanical (Epi-LASIK) versus alcohol-assisted laser epithelial keratomileusis (LASEK) for correction of myopia.SettingGazi University Medical School, Department of Ophthalmology, Ankara, Turkey.DesignRetrospective study.MethodsTwenty-two eyes treated with LASEK and twenty eyes treated with Epi-LASIK were evaluated with a mean follow-up duration of 45 months. Mechanical separation of the epithelium was performed with Lasitome epithelial separator, and alcohol-assisted separation with 25 s application of 18% alcohol. Laser ablation was performed with the ESIRIS laser. All patients were examined daily until epithelial closure; at 1, 3, 6, and 12 months; and every year subsequently. Main outcome measures were uncorrected visual acuity (UCVA), manifest refraction, haze, and gray scale value in confocal microscopy, efficacy and safety indexes.ResultsPreoperative myopic spherical equivalent refraction was −4.65 ± 1.74 D in the LASEK and −3.87 ± 1.30 D in the Epi-LASIK-treated eyes (p = 0.36). Of both LASEK and Epi-LASIK-treated eyes, 95% achieved 20/25 or better final UCVA. The grade of haze and mean gray scale value in confocal microscopy were similar in LASEK and Epi-LASIK-treated eyes at all postoperative periods. The efficacy index was 0.94 in LASEK group and 0.96 in Epi-LASIK group (p = 0.44). The safety index was 1.01 in LASEK group and 1.02 in Epi-LASIK group (p = 0.42).ConclusionsBoth LASEK and Epi-LASIK offer safe and effective correction of myopia in the long term.     

Effect of corona wind,current, electric field and energy consumption on the reduction of the thawing time during the high-voltage electrostatic-field (HVEF) treatment process

Electric energy plays an important role in reducing the thawing time and accelerating the entire thawing process. Corona wind speed was increased by increasing the applied voltage and current, which were 0.87 ± 0.19, 1.22 ± 0.19, 1.49 ± 0.13 m/s under 8, 10, 12 kV with 3, 5, 10 μA; 1.01 ± 0.12, 1.24 ± 0.17, 1.49 ± 0.10 m/s under − 8, − 10, − 12 kV with 5, 9, 14.5 μA. The models T1, T2, and T3 were designed to study the effects of current, corona wind and electric field on thawing, respectively. T1: a thin stainless-steel sheet covered the top of stainless-steel box with 10 g frozen distilled water; T2: a plastic sheet was placed under the stainless-steel box; T3: a plastic sheet covered the top of plastic box. Electric field alone cannot affect thawing time, which could be maximally reduced by 1/2 compared to that of air thawing.Industrial relevanceWe have studied HVEF thawing for several years because of its many advantages, such as the quick thawing of frozen meat with little energy consumption and good post-thawing quality. The mechanism of HVEF thawing and the reduction of the thawing time, which are important for the industrial application of new technology from principle to design, must be clarified. Meanwhile, this emerging technology will be beneficial for the food-thawing field.