Lower tear meniscus in computer reading task with and without soft contact lens

Dry eye is the major contributor to computer vision syndrome. The reductions in the blink rate and amplitude have been considered as the possible mechanisms leading to this condition. The purpose of this study is to evaluate the changes in the lower tear meniscus heights and areas in the computer reading task, in dry eye subjects, with and without soft contact lenses. In this quasi-experimental study, 39 subjects (with mean age of 21.2 ± 2.4 years), with dry eye, were enrolled.  The lower tear meniscus height and area (TMH, TMA) of the right eye was captured by Spectral Optical Coherence Tomography before and after 45 minutes of reading task behind desktop 17” Cathode Ray Tube monitors. The same procedure was performed after the insertion of the hydrogel soft contact lenses with 58% water content. The results of TMHs, TMAs were analyzed with a repeated measures analysis of variance (ANOVA) with two within-subject factors.: The mean ± standard error of  TMH and TMA pre and post computer tasks were 283.6± 25.4 µm, 0.029±0.005 mm2, 297.6±20.7 µm , 0.036 ± 0.005 mm2 respectively. After contact lens insertion, the mean TMH and TMA pre and post computer task were 231.6 ± 10.6 µm, 0.020±0.0019 mm2, 213.0±9.0 µm, 0.018 ± 0.0011 mm2, respectively. Repeated measures analysis of variance showed that the changes in TMH (P=0.86) and TMA (P=0.37) after computer task, were not statistically significant, while the insertion of the soft contact lens had reduced the TMH and TMA significantly (P<0.001 for both). After 45 minutes of reading task behind desktop monitors, the tear volume has not changed, with and without high water SCLs. A reduction in tear volume might be expected with longer duration of computer task or at late hours of the day. The creation of a more stable tear film should be considered in the management strategies for shorter duration of work behind desktop monitors

Considering time-interaction terms using parametric survival models for interval-censoring data

Background: Many of the variables which are investigated in survival research are time-invariant, i.e. their values do not change over time. But their effects, may yet vary over time. Thus, the change in behavior that occurs over time needs to be included in the analysis. This can be done by adding time-interaction terms to the model. Method: In this research, a parametric survival model, which is capable of evaluating the effects of time-dependent variables, was applied for interval-censored data such that the time to invariant variables interaction terms were considered as time-dependent variables. Results: Using a practical example, the results of the study show that this model can alter the interpretations regarding the effects of exploratory variables. Conclusion: when dealing with fixed variables whose effects change over time, the researcher can incorporate their interaction effect with time, and treat them as time-dependent variables and obtain appropriate inferences

Comparison of CT-Number and Gray Scale Value of Different Dental Materials and Hard Tissues in CT and CBCT

Introduction: Computed tomography (CT) and cone-beam CT (CBCT) are valuable diagnostic aids for many clinical applications. This study was designed to compare the gray scale value (GSV) and Hounsfield unit (HU) of selected dental materials and various hard tissues using CT or CBCT. Methods and Materials: Three samples of all test materials including amalgam (AM), composite resin (CR), glass ionomer (GI), zinc-oxide eugenol (ZOE), calcium-enriched mixture (CEM) cement, AH-26 root canal sealer (AH-26), gutta-percha (GP), Coltosol (Col), Dycal (DL), mineral trioxide aggregate (MTA), zinc phosphate (ZP), and polycarbonate cement (PC) were prepared and scanned together with samples of bone, dentin and enamel using two CBCT devices, Scanora 3D (S3D) and NewTom VGi (NTV) and a spiral CT (SCT) scanner (Somatom Emotion 16 multislice spiral CT);. Subsequently, the HU and GSV values were determined and evaluated. The data were analyzed by the Kruskal-Wallis and Mann-Whitney U tests. The level of significance was determined at 0.05. Results: There were significant differences among the three different scanners (P<0.05). The differences between HU/GSV values of 12 selected dental materials using NTV was significant (P<0.05) and for S3D and SCT was insignificant (P>0.05). All tested materials showed maximum values in S3D and SCT (3094 and 3071, respectively); however, bone and dentin showed low/medium values (P<0.05). In contrast, the tested materials and tissues showed a range of values in NTV (366 to15383; P<0.05). Conclusion: Scanner system can influence the obtained HU/GSV of dental materials. NTV can discriminate various dental materials, in contrast to S3D/SCT scanners. NTV may be a more useful diagnostic aid for clinical practice

Evaluation of diagnostic accuracy and dimensional measurements by using CBCT in mandibular first molars

Background: This study aimed to assess the diagnostic accuracy of cone beam computed tomography (CBCT) and quantitatively evaluate the morphology of mandibular first molars using CBCT. Material and Methods: Twenty-four double-rooted mandibular first molars were evaluated by NewTom VGi CBCT. The distance from the furcation and apex to the cementoenamel junction (CEJ), diameter and thickness of canal walls, the buccolingual (BL) to mesiodistal (MD) ratio (ΔD), prevalence of oval canals at different sections and taper of the canals were all determined. In order to assess the diagnostic accuracy of CBCT, distance from the furcation and apex to the CEJ and thickness of canal walls at the CEJ and apex were compared with the gold standard values (caliper and stereomicroscope). Statistical analyses were carried out using intraclass correlation coefficient (ICC), paired t-test and repeated measures ANOVA. Results: A high correlation existed between the CBCT and gold standard measurements ( P <0.001). In dimensional measurements, length of mesial root was higher than the distal root and lingual furcation was farther from the CEJ than the buccal furcation ( P <0.001). An important finding of this study was the mesiodistal taper of the mesiobuccal (MB) and mesiolingual (ML) canals; which was equal to 0.02. Conclusions: CBCT has acceptable diagnostic accuracy for measurement of canal wall thickness. Cleaning and shaping of the canals should be performed based on the unique anatomy of the respective canal; which necessitates the use of advanced imaging techniques for thorough assessment of root canal anatomy in a clinical settin

Comparison of an Italian Chart with an Iranian Chart in Visual Acuity Measurement

Background: Taking visual acuity is an important part of an eye routine examination. This study was conducted to compare visual acuity measured using an Iranian digital tumbling E chart with visual acuity measured using an Italian digital tumbling E chart as a familiar foreign chart.Materials and Methods: This study was carried out on 200 participants (400 eyes; healthy n=40, glaucoma n=40, retinal disorders n=40, post lasik n=40, corneal n=40) with mean age 44.28 years. Visual acuity of both eyes of half of the subjects (n=100, n=20 from each group), was first measured using the Italian digital chart and then measured using Iranian digital chart. Visual acuity of the rest of subjects (n=100, n=200 from each group) was first measured using the Iranian digital chart and then measured using the Italian digital chart. Measured visual acuities were recorded in logMAR notation.Results: The mean of the Iranian and Italian Tumbling E chart is 0.280±0.012 and 0.277±0.012, respectively. Paired t-test used to evaluate the mean difference between two groups (p=0.721) indicated that there was no statistically significant difference between means of the two tests. Spearman correlation coefficient for the results of both tests was 0.942 (p&lt;0.001), which was statistically significant and could be categorized as a strong positive correlation.Conclusion: The two digital Tumbling E charts acted similarly at different levels of acuity in different disorders. However, the Iranian chart requires a more accurate design for optotypes of the lower acuity lines in order to obtain more accurate measurement of visual acuities in healthy subjects

Valsalva maneuver using a Handmade Device in Supraventricular Tachycardia Reversion; a Quasi Experimental Study

Introduction: The use of vagal nerve stimulation is identified as a proper treatment option in patients with stable supraventricular tachycardia (SVT). This study aimed to assess the success of Valsalva maneuver via a handmade device in reversion of SVT. Methods: In this quasi experimental study, using a handmade device, vagus nerve stimulation was performed for SVT patients presenting to emergency department or cardiac intervention unit and the success rate and its related factors were assessed. Results: 100 patients with the mean age of 53.05 ± 13.70 years were studied (67% female). 12 (12%) cases were unable to do the maneuver. Out of the 88 (88.0%) patients who could perform the maneuver, 75 (85.2%) cases were unsuccessful. Dysrhythmia was controlled in 6 (6.8%) cases on the first attempt and in 7 (8.0%) cases on the second one (14.8% total success rate). 12 of the 13 cases (92.3%) with successful maneuver had history of SVT (p = 0.031). There was not any significant association between success rate and sex (p = 0.084), age (p = 0.744), or other medical histories (p ≥ 0.05). Conclusion: Based on the results of the present study, the success rate of Valsalva maneuver with the mentioned handmade device was calculated to be 14.8%. The only independent related factor of successful reversion was SVT history.

Cytotoxicity of Nanoliposomal Cisplatin Coated with Synthesized Methoxypolyethylene Glycol Propionaldehyde in Human Ovarian Cancer Cell Line A2780CP

Purpose: To evaluate the cytotoxicity of pegylated nanoliposomal cisplatin on human ovarian cancer cell line A2780CP.Methods: Synthesized methoxypolyethylene glycol (mPEG) propionaldehyde was characterized by 1Hnuclear magnetic resonance (1H-NMR) and Fourier transform infrared spectroscopy (FTIR) and used as coating agent for the preparation of liposomal nanodrug formulation by reverse phase evaporation method. The characteristics of the nanoparticles were evaluated by dynamic light scattering (DLS) and scanning electron microscopy (SEM). Encapsulation efficiency was determined spectrometrically at 214.42 nm by inductively coupled plasma spectroscopy (ICP-OES). The cytotoxicity of both pegylated nanoliposomal and free cisplatin were evaluated by 3- [4, 5 dimethyl-2-thiazolyl] -2, 5- diphenyltetrazolium bromide (MTT) assay and expressed as half-maximal inhibitory concentration (IC50).Results: The mean diameter and zeta potential of drug-loaded liposomal particles and empty nanoliposomes were 125 ± 2.9 nm and -16.6 mV, 108 ± 2.2 nm and -27.2 mV, respectively, while the cytotoxicity (IC50) of free cisplatin and nanodrug formulation were 93.6 ± 3.1 μg/mL and 67.8 ± 2.3 μg/mL, respectively. In vitro toxicological results indicate that the formulation exhibited approximately 1.4-fold cytotoxicity compared with the free drug. Drug encapsulation efficiency of the nanoliposomes was approximately 98 ± 1 %.Conclusion: The findings show that the cytotoxicity of pegylated nanoliposomal cisplatin is higher than that of free cisplatin in human ovarian cancer cell line A2780CP. In vivo studies are, however, required to ascertain its therapeutic potentials.Keywords: Liposome, Nanodrug, Ovarian cancer, Polyethylene glycol, Cisplatin, Drug delivery, Cytotoxicit

Comparison of Two Marketed Hydroxypropyl Methylcellulose Based Artificial Tear Drops in Young Patients with Dry Eye Syndrome

Background: Artificial tears have been among the first line of therapy in management of Dry Eye Syndrome (DES). This study was conducted to compare a local artificial tear with an imported one in reduction of DES. This comparison would help to evaluate the cost and benefits of each drop in the proper management of DES.Materials and Methods: In this double-blind randomized clinical trial study, a total 65 students meeting our inclusion criteria for DES entered the study. The OSDI questionnaire, TBUT, corneal and conjunctival staining and Schirmer test, were performed. The patients were divided into two groups by block randomization. Group 1 received first drop and group 2 received second drop. Both groups were instructed to use the drops 4 times a day for 14 days. The same tests were performed by the same examiner who was blind to the treatment type after two weeks. Repeated measured ANOVA was used to analyze the data.Results: A total of 58 patients completed the study. In both groups, after the intervention, the OSDI scores (P&lt;0.001), TBUT score (P=0.041), corneal (P&lt;0.001) and conjunctival staining scores (P&lt;0.001) showed improvement in compare to those before the intervention. However, the Schirmer test score did not show significantly difference before and after intervention. In comparing two groups the OSDI scores, the TBUT score, the corneal and conjunctival staining scores and the Schirmer scores did not show statistically significant difference.Conclusion: The two artificial tears equally reduced the symptoms and signs of DES in two weeks

Comparative Evaluation of Spectral Transmittance of Some Welding Glasses with ANSI Z87.1

Background: Welding emits harmful rays to the eyes. We evaluate and compare the UV, blue light and IR transmittance characteristics of some currently available welding safety protectors with ANSI Z87.1 criteria.Materials and Methods: Three type of welding safety protectors (three of each type) have been evaluated for spectral transmittance. One-sample T-test was performed to establish is there a statistically significant difference between the standard criteria and UV, blue and IR regions for the welding protectors (α=0.05).Results: In ultraviolet (UV) (far and near) region, two types of the tested protectors (P1, P2) transmitted lower than the maximum allowable value specified in the standard (P&lt;0.001). In infrared (IR) spectrum only one type (P3) transmitted lower than the maximum allowable value specified in the standard (P&lt;0.001). In blue light region, all of the tested protectors transmitted lower than the maximum allowable value specified in the standard (P&lt;0.001).Conclusion: Although all of the tested glasses could meet some parts of the criteria, but none of them could meet the complete spectral transmittance requirements of ANSI Z87.1

How Much of Hazardous Blue Light is Transmitted By Spectacle Lenses?

This is a Letter to the Editor and does not have an abstract