Viscoelastic Behavior of Glass-Fiber-Reinforced Silicone Composites Exposed to Cyclic Loading.

The aim of this work was to analyze the influence of fibers on the mechanical behavior of fiber-reinforced elastomers under cyclic loading. Thus, the focus was on the characterization of structure-property interactions, in particular the dynamic mechanical and viscoelastic behavior. Endless twill-woven glass fibers were chosen as the reinforcement, along with silicone as the matrix material. For the characterization of the flexible composites, a novel testing device was developed. Apart from the conventional dynamic mechanical analysis, in which the effect of the fiber orientation was also considered, modified step cycle tests were conducted under tensile loading. The material viscoelastic behavior was studied, evaluating both the stress relaxation response and the capability of the material to dissipate energy under straining. The effects of the displacement rate of the strain level, the amplitude of the strain applied in the loading-unloading step cycle test, and the number of the applied cycles were evaluated. The results revealed that an optimized fiber orientation leads to 30-fold enhanced stiffness, along with 10 times higher bearable stress. The findings demonstrated that tailored reinforced elastomers with endless fibers have a strong influence on the mechanical performance, affecting the structural properties significantly.

The association between personality disorders/traits and violent eye trauma.

AIMS: To determine the prevalence of various personality disorders in patients with open globe injuries caused by violent eye trauma. MATERIALS AND METHODS: One-hundred patients were divided equally to case and control groups. The case group was selected from admitted patients with open globe injury following a violent act. We considered open globe injuries not involved in violence as the control group. All patients interviewed using SCID-II questionnaire. RESULTS: The mean age was 30.7 ± 9.2 year and 34.4 ± 13.1 year for the case and control groups, respectively, (P > 0.05). The married population was more frequent in the control group (P = 0.027). Forty-three patients (86%) in the case group and 23 patients (46%) in the control group demonstrated some personality disorder (P < 0.001). In both groups, cluster B was most frequent. The antisocial personality disorder was more prevalent in the case group. (P = 0.046 and P = 0.006, respectively). The ocular trauma score (OTS) and the mean visual acuity was significantly worse in the case group (P = 0.028 and P = 0.044). CONCLUSIONS: Personality disorders are probably important factors in those who acquire an open eye injury during violent behavior. This group had a poor visual outcome. We suggest that this population merits appropriate psychiatric consultation for detection of personality disorders.

Closantel; a veterinary drug with potential severe morbidity in humans.

BACKGROUND: Closantel is a halogenated salicylanilide with a potent anti parasitic activity. It is widely used in management of parasitic infestation in animals, but is contraindicated in humans. CASE PRESENTATION: A 34-year-old man with depression was referred to our center with progressive loss of vision in both eyes 10 days after unintentional ingestion of three 500 mg tablets of Closantel. On fundus examination, left optic disc margin was blurred. His bilateral visual acuity was no light perception (NLP) despite prescribed IV erythropoietin injections 20,000 units daily for 3 days and 1gr intravenous methylprednisolone acetate for 3 days followed by 1 mg/kg oral prednisolone. On macular optical coherence tomography (OCT), a disruption in outer retina was observed. Electroretinogram and visual evoked potential tests showed visual pathway involvement. CONCLUSIONS: Destruction of neurosensory retina and visual pathways after accidental Closantel use is related to severe visual loss. This case alerts us about the destructive effect of this drug on humans even in low dosage which necessitates preventive efforts to reduce the chance of this morbid side effect.

Ocular trauma treated with pars plana vitrectomy: early outcome report.

AIM: To evaluate demographic variables and visual outcomes, among patients with ocular injuries involving the posterior segment, managed with pars plana vitrectomy. METHODS: The records of patients were studied retrospectively from March to September 2010, to determine the age, gender, place of occurrence of trauma, visual acuity, anatomical site, nature of injury, wound length, the presence of an afferent pupillary defect, and the timing of vitrectomy. The Ocular Trauma Score was measured. The minimum follow-up from presentation was 6mo. RESULTS: Ninety patients (77 males, 13 females), with a mean age of 32.7±15.8y were included over the 6-month period. The majority of cases occurred in the workplace (47 patients), followed by home (14 patients). The mean visual acuity (logMAR) of patients significantly improved from 2.36±0.72 preoperatively to 1.50±1.14 postoperatively. Twenty-three patients had preoperative vision better than 2.0 logMAR, the postoperative visual acuity was significantly better among these patients than patients with worse than 2.0 logMAR (P<0.001). Visual improvement between groups with early vitrectomy (<7d) and delayed vitrectomy (>7d) was not significantly different (P=0.66). Postoperative visual acuity was not significantly different between patients with injury in Zone I and II (P=0.64), but patients with injury in Zone III had significantly poorer visual acuity (P=0.02). Patients with relative afferent pupillary defect had significantly poorer postoperative visual acuity (P=0.02). Preoperative visual acuity, the difference of preoperative and postoperative visual acuity, and postoperative visual acuity were significantly different between groups with different ocular trauma scores (P<0.001). CONCLUSION: Trauma is more likely to occur in men under 40y of age and in the workplace. The favorable final visual outcome is associated with the absence of afferent pupillary defect, ocular trauma score and presenting visual acuity as well as the zone of injury, and not associated with the timing of vitrectomy.

Work-related eye injury: the main cause of ocular trauma in Iran.

PURPOSE: Occupational eye injuries are among the major causes of ocular trauma and can cause severe visual impairment, with even minor injuries incurring considerable financial costs due to work absenteeism. This study was designed to evaluate the epidemiology of eye trauma and the role of occupational injuries at Farabi Eye Hospital, which is the largest eye hospital in Iran. METHODS: In this prospective, cross-sectional study, 822 eyes from 768 trauma patients presenting to Farabi Eye Hospital were enrolled in the study. The Birmingham Eye Trauma Terminology System and the United States Eye Injury Registry model were adopted as the basis for the study questionnaire. The questionnaires were completed through in-person interviews and comprehensive ocular examinations. RESULTS: The mean age of ocular trauma patients was 31.11 years, and 685 (89.2%) patients were male. Of all eye injuries, 73.7% were work-related. Only 2.2% of the patients were wearing safety goggles at the time of injury. History of previous eye trauma was positive in 44.3% of cases. An Ocular Trauma Score 3 or more was present in 4% of patients. CONCLUSIONS: Work-related eye trauma is the major cause of eye injury in Iran and most often occurs as a result of the lack of proper eye protection. Most work-related eye injury patients are young men.

Retinopathy of prematurity in infants with late retinal examination.

PURPOSE: To report the incidence, severity and risk factors of retinopathy of prematurity (ROP) in premature infants with late ROP examination in Farabi Eye Hospital. METHODS: In a retrospective study from January 2001 to July 2007, hospital records of premature infants who were examined later than 9 weeks after birth were reviewed to determine the incidence, severity and possible risk factors of ROP including gender, singleton or multiple gestations, gestational age (GA), birth weight (BW), oxygen therapy,blood transfusion, phototherapy, respiratory distress syndrome (RDS), mechanical ventilation,intraventricular hemorrhage and sepsis as well as age at initial examination. RESULTS: Out of a total of 797 infants referred for ROP screening during the study period,216 (27.1%) had late examinations at a mean age of 141.7± 150.4 (range 64-1,460) days. Of these, 87 (40.3%) had different stages of ROP, 65 (30.1%) had stage 4 or 5 disease including 34 (16.2%) infants with stage 5 ROP in both eyes which was untreatable. Lower GA (P<0.001), RDS (P=0.041) and blood transfusion (P=0.009) were associated with the development of ROP. CONCLUSION: The overall prevalence of ROP and the incidence of severe ROP in particular,were unacceptably high in premature infants with late screening. These findings necessitate interventions to optimize timely referral for screening of premature infants.

Retinopathy of Prematurity: Single versus Multiple-Birth Pregnancies.

PURPOSE: To compare the frequency and severity of retinopathy of prematurity (ROP) among singleton and multiple-birth neonates referred to Farabi Eye Hospital, Tehran- Iran. METHODS: In this retrospective study, records of 99 consecutive neonates from multiplegestation pregnancies including 68 twins, 26 triplets and 5 quadruplets who were screened for ROP from 2002 to 2004 were reviewed. The frequency, severity and risk factors for ROP were determined and compared to a group of singletons who were matched in terms of gender, birth weight (BW), gestational age (GA), oxygen therapy, respiratory distress syndrome, blood transfusion, sepsis and phototherapy. RESULTS: ROP was present in 12.1% of multiple-birth neonates as compared to 15.1% of singletons (P=0.53). Threshold ROP was present in 6.1% of multiple-birth neonates versus 7.1% of singletons (P=0.62). ROP was detected in 60% of quadruplets versus 9.6% of twins and triplets; threshold disease was observed in 40% of quadruplets as compared to 4.2% of twins and triplets (P<0.03). However, considering the effect of BW and GA, logistic regression analysis revealed no statistically significant difference in the frequency and severity of ROP among subgroups of multiple-gestation pregnancies. CONCLUSION: There was no significant difference between multiple-birth neonates and matched singletons in terms of frequency and severity of ROP. Any apparent higher rate may be due to independent risk factors such as low birth weight and gestational age rather than multiple pregnancies per se. Screening for ROP in multiple gestation births may be conducted according to standard protocols applied for singletons.

Long-term surgical outcome of posterior choroidal melanoma treated by endoresection.

PURPOSE: To report the visual acuity, enucleation rates, and initial mortality after transvitreal endoresection of posterior uveal melanoma. METHODS: Twenty consecutive patients with medium-sized posterior choroidal melanomas were treated. Vitrectomy was performed, followed by posterior hyaloid dissection, retinotomy, melanoma removal with a vitrectomy probe, retinal reattachment with perfluorocarbon liquid, and silicone oil or gas exchange. RESULTS: Twenty patients (13 men [65%] and 7 women [35%]) were included in the study. The mean patient age +/- SD was 47.1 +/- 16 years (range, 22-70 years). Tumor thickness and tumor diameter ranged from 5.5 mm to 11 mm and 8.0 mm to 15.7 mm, respectively. Preoperative visual acuity ranged from hand motion to 20/40, and postoperative visual acuity ranged from no light perception to 20/30. Two eyes (10%) were enucleated during tumor resection due to severe bleeding. Enucleation was performed on 3 eyes (15%) during follow-up due to tumor recurrence at the edge of surgical coloboma in 1 patient, new focus of tumor in another sector distant from surgical coloboma in 1 patient, and painful blind eye in 1 patient. Fifteen eyes (75%) were saved. One patient (5%) died of metastasis to the liver. The mean follow-up period +/- SD was 89.55 +/- 38.4 months (range, 24-132 months. CONCLUSION: These data suggest that transvitreal endoresection of posterior uveal melanoma is an acceptable management option to conserve the globe and functional vision in selected patients. Distant metastasis is an infrequent event in this modality of treatment.

The Persian Wednesday Eve Festival "Charshanbe-Soori" fireworks eye injuries: a case series.

PURPOSE: To describe the clinical spectrum and severity of eye injuries sustained during the Persian Wednesday Eve Festival "Charshanbe-Soori" and to identify the fireworks devices involved. METHODS: Prospectively, consecutive patients treated for fireworks-related eye injuries in the emergency room at Farabi Eye Hospital, Tehran, over 3 days around the occasion in 2000, 2001, and 2002 were studied. RESULTS: Four hundred thirty-seven cases of eye injuries with an age range of 2-74 (median 17; SD 11.1) years were studied: 84.6% were male; 18.6% of the injuries were bilateral; 79.9% of the injured were bystanders or passersby. Eleven types of devices were involved, of which seven were explosives and eight were homemade. "Narenjaks," homemade grenades, were involved in 62.2%, firecrackers in 14.8%, and sparklers in 6.2% of the events. Injuries were categorized as severe in 49% of cases, and 45 (10.4%) people were hospitalized. Five eyes with no light perception and/or enucleation, 33 cases of monocular blindness, 54 (12.3%) cases of open globe (including intraocular foreign bodies) were observed. Grenades, bystander and passerby roles, outdoor context, a relatively older age, lower socioeconomic status, and male gender in the subset of passive roles were the determinants of more severe injuries (all p values < 0.05). Lid injuries (67.7%), corneal abrasions (51.6%), hyphema (48.1%), superficial foreign bodies (32.5%), and corneal contusions (13.8%) were the five leading injuries. CONCLUSIONS: In Iran, fireworks cause frequent and diverse injuries during the Wednesday Eve Festival and are a leading cause of severe eye injuries and monocular blindness.

Corneal endothelial cell density and morphology in normal Iranian eyes.

BACKGROUND: We describe corneal endothelial cell density and morphology in normal Iranian eyes and compare endothelial cell characteristics in the Iranian population with data available in the literature for American and Indian populations. METHODS: Specular microscopy was performed in 525 eyes of normal Iranian people aged 20 to 85 years old. The studied parameters including mean endothelial cell density (MCD), mean cell area (MCA) and coefficient of variation (CV) in cell area were analyzed in all of the 525 eyes. RESULTS: MCD was 1961 +/- 457 cell/mm2 and MCA was 537.0 +/- 137.4 microm2. There was no statistically significant difference in MCD, MCA and CV between genders (Student t-test, P = 0.85, P = 0.97 and P = 0.15 respectively). There was a statistically significant decrease in MCD with age (P < 0.001, r = -0.64). The rate of cell loss was 0.6% per year. There was also a statistically significant increase in MCA (P < 0.001,r = 0.56) and CV (P < 0.001, r = 0.30) from 20 to 85 years of age. CONCLUSION: The first normative data for the endothelium of Iranian eyes seems to confirm that there are no differences in MCD, MCA and CV between genders. Nevertheless, the values obtained in Iranian eyes seem to be different to those reported by the literature in Indian and American populations.