Realization of metal-insulator transition and oxidation in silver nanowire percolating networks by terahertz reflection spectroscopy

Metal nanowires (NWs) enable versatile applications in printed electronics and optoelectronics by serving as thin and flexible transparent electrodes. The performance of metal NWs as thin electrodes is highly correlated to the connectivity of NW meshes. The percolation threshold of metal NW films corresponds to the minimum density of NWs to form the transparent, yet conductive metal NW networks. Here, we determine the percolation threshold of silver NW (AgNW) networks by using morphological analysis and terahertz (THz) reflection spectroscopy. From the divergent behavior of carrier scattering time and the increase of carrier backscattering factor, the critical NW density at which crossover from Drude to non-Drude behavior of THz conductivity occurs can be unambiguously determined for AgNW thin films. Furthermore, the natural oxidation of AgNWs which causes the gradual reduction of the connectivity of the AgNW network is also realized by the THz spectroscopy. The selective oxidation of NW-to-NW junctions weakens the ohmic contact, and for AgNWs near a critical density, it can even lead to metal-insulator transition. The presented results offer invaluable information to accelerate the deployment of metal nanowires for next-generation electronics and optoelectronics on flexible substrates.

Patterns and predictors of non-use of family planning methods in Ethiopian women: a panel survey

PURPOSE

Family planning (FP) is a key global health issue for achieving millennium development goals by 2015. The aim of this study was to identify predictors of changes in FP practice before and after interventions among Ethiopian women of reproductive age in a rural area.

METHODS

This study used a panel survey to identify predictors that placed women at greater risk for non-use of FP methods. The sample consisted of 407 women aged 19-49 years old living in a rural community of Ethiopia who completed both a baseline and follow-up survey. Trained local enumerators conducted face-to-face interviews during home visits. Patterns of FP practice were categorized into four groups: FP use at both baseline and follow-up; use at baseline but non-use at follow-up; non-use at baseline but use at follow-up; non-use at both baseline and follow-up. Logistic regression and classification and regression tree analyses were used.

RESULTS

In a binary logistic regression, women over 35 years old with a negative attitude towards FP and resided in the Sibu area were less likely to start FP practice. Women over 35 years who were in poor health and resided in Sibu were less likely to continue FP practice. For the decision tree, age was the primary node for FP non-users at baseline while area of residence was the primary node for FP users at baseline.

CONCLUSION

Age, health status, attitude towards FP, and area of residence are the primary considerations when developing FP interventions for Ethiopian women in a resource-limited rural area.

Measurement of bioimpedance and cell viability during ischemia-reperfusion in the rat liver

During liver resection and liver transplant, liver is damaged by ischemia-reperfusion injury. Until now, there is no approved method to measure or predict the extent of liver injury during the operation. This is the preliminary study to make the real time monitoring system by quantification of bioimpedance and ischemiareperfusion reperfusion injury in liver. Sprague-Dawley rats were subjected to different periods of 70% partial hepatic ischemia (30, 60, 90 and 120minutes ischemia) and reperfusion. We measured changes of liver tissue bioimpedance (120Hz-100KHz) every five minutes. Cell viability was assessed by metabolic capacity of fatty acid (palmitic acid metabolic rate), ATP content and histological examination (H/E and TUNEL stain) at every 30 minutes interval during ischemia.

Multicenter phase II study of sunitinib in patients with non-clear cell renal cell carcinoma

BACKGROUND

Retrospective and molecular biologic data suggest that sunitinib may be effective in patients with non-clear cell renal cell carcinoma (nccRCC).

PATIENTS AND METHODS

Eligibility criteria included advanced nccRCC except for collecting duct carcinoma and sarcomatoid carcinoma without identifiable renal cell carcinoma subtypes. Patients were treated with 50 mg/day oral sunitinib for 4 weeks, followed by 2 weeks of rest. The primary end point was overall response rate (RR).

RESULTS

Thirty-one eligible patients were enrolled. Twenty-four patients (77%) had prior nephrectomy. By Memorial Sloan-Kettering Cancer Center criteria, 8 patients (26%) had poor risk and 14 (45%) had intermediate risk. Twenty-two patients had papillary renal cell carcinoma (RCC), and three had chromophobe RCC. Eleven patients had partial response with a RR of 36% (95% confidence interval (CI) 19% to 52%) and an additional 17 patients (55%) had stable disease. Median duration of response was 12.7 months (95% CI 6.3-19.1 months), and median progression-free survival was 6.4 months (95% CI 4.2-8.6 months). At a median follow-up duration of 18.7 months (95% CI 13.7-23.7 months), 13 patients (42%) had died, resulting in an estimated median survival of 25.6 months (95% CI 8.4-42.9 months). Toxicity profiles were commensurate with prior reports.

CONCLUSIONS

Sunitinib has promising activity in patients with nccRCC (NCT01219751).

Carrier dynamics in InN nanorod arrays

In this report, we investigated ultrafast carrier dynamics of vertically aligned indium nitride (InN) nanorod (NR) arrays grown by molecular-beam epitaxy on Si(111) substrates. Dominant band filling effects were observed and were attributed to a partial bleaching of absorption at the probe wavelengths near the absorption edge. Carrier relaxation in nanorod samples was strongly dependent on the rod size and length. In particular, a fast initial decay was observed for carriers in NRs with a small diameter (~30 nm), the lifetime of which is much shorter than the carrier cooling time, demonstrating the substantial surface-associated influence on carrier relaxation in semiconductor nanostructures.

Plasmonic green nanolaser based on a metal-oxide-semiconductor structure

Realization of smaller and faster coherent light sources is critically important for the emerging applications in nanophotonics and information technology. Semiconductor lasers are arguably the most suitable candidate for such purposes. However, the minimum size of conventional semiconductor lasers utilizing dielectric optical cavities for sustaining laser oscillation is ultimately governed by the diffraction limit (∼(λ/2n)(3) for three-dimensional (3D) cavities, where λ is the free-space wavelength and n is the refractive index). Here, we demonstrate the 3D subdiffraction-limited laser operation in the green spectral region based on a metal-oxide-semiconductor (MOS) structure, comprising a bundle of green-emitting InGaN/GaN nanorods strongly coupled to a gold plate through a SiO(2) dielectric nanogap layer. In this plasmonic nanocavity structure, the analogue of MOS-type "nanocapacitor" in nanoelectronics leads to the confinement of the plasmonic field into a 3D mode volume of 8.0 × 10(-4) μm(3) (∼0.14(λ/2n)(3)).

Prognostic factors and survial of advanced renal cell carcinoma with predominant sarcomatoid histology

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Background: Sarcomatoid renal cell carcinoma (SRCC) is known to have aggressive clinical course and poor response to treatment. Very limited data of clinical feature, prognostic factor, and survival are available for advanced disease with predominant sarcomatoid histology. We evaluated clinical features, response to treatment, and prognostic factors for survival.

Methods: Between 2001 and 2010, 30 patients with metastatic or recurrent RCC with predominant sarcomatoid histology (sarcomatoid component 30% or more for resected kidney or exclusive sarcomatoid carcinoma on needle biopsy) were treated at our institution. We reviewed these patients' records to identify clinical and pathologic features which could affect survival. The role of nephrectomy and systemic therapy on patient outcome was also investigated.

Results: There were 20 male and 10 female patients with a median age of 58 years (range, 43–83). Twenty patients had initially metastatic disease and 16 patients (53%) had ECOG performance status (PS) of 0–1. The most frequent metastatic site was lung (57%) followed by bone (43%) and distant lymph nodes (23%). Fourteen (70%) out of 20 patients with initially metastatic disease underwent primary nephrectomy and six patients also underwent metastasectomy. The median % of sarcomatoid component was 80% (range, 30–100%). All patients (N=10) who received immunotherapy had progressive disease as their best response and only one out of 5 patients treated with sunitinib or everolimus had a partial response. With a median follow-up duration of 22 months, the median survival was 3.6 months (95% CI, 0∼7.5) with 6-month survival rate of 43%. Only ECOG PS had impact on survival (P<0.001: ECOG=0, 14.1 months; ECOG=1, 7.4 months; ECOG=2, 3.2 months, and ECOG=3, 1.64 months). Survivals for initially metastatic disease were not significantly different whether patients underwent nephrectomy or not (2.0 months vs. 3.4 months, HR=0.62, 95% CI, 0.16–2.44 after correcting for potential prognostic factors).

Conclusions: Patients with SRCC have a fulminant clinical course and the majority of patients had disease progression irrespective of any treatment. Only performance status dose have impact on overall survival.

No significant financial relationships to disclose.

Phase II study of a polyethoxylated castor oil–free, polymeric micelle formulation of paclitaxel for patients with advanced urothelial cancer previously treated with gemcitabine and platinum

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Background: Paclitaxel-loaded polymeric micelle (Genexol-PM; G-PM) is a novel polyethoxylated castor oil (Cremophor EL [CrEL])-free formulation of paclitaxel. This multicenter phase II study was designed to evaluate the efficacy and safety of the G-PM monotherapy for the treatment of gemcitabine- and cisplatin-refractory advanced urothelial cancer.

Methods: Patients with advanced urothelial cancer received G-PM 240 mg/m2 intravenously over 3 hours every 3 weeks without premedication as salvage chemotherapy after failure to gemcitabine and cisplatin combination chemotherapy. Intrapatient dose escalation of G-PM to 300 mg/m2 was carried out from the second cycle if the prespecified toxicities were not observed after the first cycle.

Results: Thirty-seven patients were enrolled in this study. Platinum-free interval was less than 6 months in 72% of patients and 64% of patients were categorized into intermediate or poor prognostic group. Overall response rate was 19% including one complete response. When response occurs it is long lasting with a median response duration of 7.8 months (range 1.5∼19.3+). The median progression-free survival was 2.7 months (95% CI, 09-4.6) with a median overall survival of 5.7 months (95% CI, 3.1-8.3). The most common major grade 3-4 non-hematologic toxicity was peripheral neuropathy (sensory type 5.6% and motor type 8.3%) followed by infection (5.6%). Grade 3 or worse hematologic toxicities were observed in only one patient.

Conclusions: G-PM showed modest activity with favorable toxicity profiles when used as salvage therapy after gemcitabine-cisplatin failure in advanced urothelial cancer.

No significant financial relationships to disclose.

Multicenter prospective phase II study of sunitinib in non-clear cell type renal cell carcinoma

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Background: Sunitinib has been shown to produce a high response rate (RR), and improved progression-free survival (PFS) in patients (pts) with clear cell RCC. Retrospective data suggest sunitinib may be effective in papillary and chromophobe RCC. We conducted a multicenter phase II trial of sunitinib in non-clear cell RCC (nccRCC).

Methods: Eligibility criteria included PS 0-1, measurable disease, and adequate organ function. Pts with brain metastases were not excluded if controlled without steroid dependence. Response assessment was performed every 6 weeks. Primary endpoint was RR. Secondary endpoints were TTP, safety and OS.

Results: Between 6/2008 and 7/2010, 29 pts with nccRCC were enrolled (total accrual 35: P0=5%, P1=20%, alpha=0.05, beta=0.2, drop-out rate 15%). Median age was 52 (18–76). Twenty-four pts (84%) had prior nephrectomy. Seven pts (24%) had poor risk and 13 (45%) had intermediate risk disease by MSKCC criteria. Twenty-one pts had papillary RCC (type II in 11 and type not- specified in 10), and 4 patients had chromophobe RCC. Two pts discontinued protocol treatment due to toxicity prior to completion of cycle 1 (one pt had cardiogenic shock 27 days after start of therapy and the other refused further treatment 5 days after therapy). Eleven pts out of 29 had partial response with a RR of 38% (95% CI, 20.2%–55.6%) and additional 15 patients (52%) had SD with a disease control rate of 90%. Response rates were not significantly different according to the histologic type (43% in papillary type and 25% in chromophobe type). Median duration of response was 12.7 months (95% CI, 2.3∼23.1) and median TTP was 6.4 months (95% CI, 4.5∼8.3). With a median FU duration of 16 months (95% CI, 8.6∼23.4), 10 pts have been dead resulting in an estimated median OS of 17.9 months. Toxicity profiles were commensurate with prior reports on Korean patients (Yoo, et al. Jpn J Clin Oncol 2010). However, there was one treatment-related death caused by acute heart failure in patient without relevant risk factors for heart disease.

Conclusions: Although our study is ongoing, the primary endpoint has been met and these data suggest that suntinib has promising activity in patients with nccRCC.

No significant financial relationships to disclose.

Outcomes of Late Corticosteroid Withdrawal after Renal Transplantation in Patients Exposed to Tacrolimus and/or Mycophenolate Mofetil: Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Corticosteroids are increasingly used in renal transplant patients to minimize organ rejection after transplantation. In attempts to reduce corticosteroids adverse effects, transplant professionals are customary attempted to taper off, and permanently stop corticosteroids after few months of administration with other immunosuppressants.

OBJECTIVE

To evaluate clinical benefits and risks of late corticosteroid withdrawal in renal transplant patients treated with tacrolimus (TAC) or mycophenolate mofetil (MMF), or both.

METHODS

A meta-analysis was performed of published randomized controlled trials that reported outcomes in kidney transplant patients who were randomized to corticosteroids maintenance or late withdrawal under concomitant immunosuppression by TAC, MMF or both. Outcomes included acute graft rejection; graft failure rate; all-cause mortality; incidence of post-transplant diabetes; change in serum creatinine and total cholesterol; and change in pediatric standardized height z-score. PubMed and Google Scholar were used in literature search between 1999 and April 1, 2010. Data were combined using unweighted random effects model.

RESULTS

Nine studies randomized 1907 patients met the inclusion criteria: TAC (n=1); MMF (n=6); both (n=2). Compared to maintenance therapy, late corticosteroid withdrawal was associated with 34% increase in the risk of acute graft rejection (95% CI for OR: 0.47-3.82); 35% and 5% reductions in the risk of graft failure and patient's all-cause mortality (95% CI for OR: 0.26-1.60; 0.23-3.93, respectively); and 4% increase in post-transplant diabetes risk (95% CI for OR: 0.45-2.41). Late corticosteroid withdrawal was associated with substantial reduction in total cholesterol levels (mean difference: 18.1 mg/dL; 95% CI: 7.1-29.0 mg/dL), but did not reduce serum creatinine levels (0.00 mg/dL; 95% CI: 0.17 to 0.17). Stopping corticosteroids was associated with better pediatric growth outcomes.

CONCLUSION

Late corticosteroid withdrawal under TAC and/or MMF-lead immunosuppression after kidney transplantation could provide benefits in terms of total cholesterol, patient and graft survival, and pediatric growth. This strategy, however did not reduce the risk of acute graft rejection, post-transplant diabetes mellitus, and deterioration in serum creatinine levels.

Resistance Exercise Did Not Alter Intramuscular Adipose Tissue but Reduced Retinol-binding Protein-4 Concentration in Individuals with Type 2 Diabetes Mellitus

Lipid accumulation in muscle is associated with diminished insulin sensitivity. It was hypothesized that resistance exercise decreases muscular adipose tissue and reduces the level of retinol-binding protein-4 (RBP4), which is linked to adipose tissue and insulin sensitivity in diabetics. Forty-four women with type 2 diabetes were randomly assigned to three groups for a period of 12 weeks: control (asked to maintain a sedentary lifestyle); resistance exercise (elastic band exercise at moderate intensity five times per week); and aerobic exercise (walking for 60 min at moderate intensity five times per week). Subcutaneous (SCAT), subfascial (SFAT) and intramuscular (IMAT) adipose tissues at mid-thigh level were assessed using computed tomography, and RBP4 level and insulin sensitivity (fractional disappearance rate of insulin, kITT) were assessed before and after intervention. Changes in SCAT, SFAT, IMAT, RBP4 and kITT were similar among the three groups. Within-group analysis revealed that body mass index and waist circumference decreased significantly in both exercise groups, but RBP4 decreased significantly only with resistance exercise. Resistance exercise did not alter muscular adipose tissue or improve insulin sensitivity.

Strong green photoluminescence from InxGa1-xN/GaN nanorod arrays

We report intense green photoluminescence (PL) from vertically aligned indium gallium nitride (InxGa(1-x)N) nanorod arrays. The formation of InxGa(1-x)N/GaN-heterostructure nanorods increases the localization depth of the radially confined carriers (> 100 meV). Temperature dependent PL peak energy of InGaN nanorods shows the characteristic S-shaped behavior, indicating the prominent carrier trapping in band-tail states associated with the nonuniformity of In content. Time-resolved PL (TRPL) response decays biexponentially and the dominant slow decay component of TRPL for InxGa(1-x)N nanorods is due to the transfer of excitons to the localized states before the radiative decay.

The role of oophorectomy for colon cancer with ovarian metastasis

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Background: A recent study demonstrated that colorectal cancer with ovarian metastases were less responsive to chemotherapy compared to extraovarian metastases. Hence, the ovary may actually represent a “sanctuary” for metastatic cells from CRC. The aim of the study was to investigate the impact of oophorectomy on survival of colorectal cancer patients with ovarian metastasis. Methods: Between 1996 and 2008, 83 colorectal cancer patients underwent oophorectomy. For the historical control, 47 colorectal cancer patients without oophorectomy were included in the analysis. Survival and its associated factors were analyzed using Kaplan-Meier method, log-rank test and Cox-regression analysis. Results: The median age was younger (48 years) in the oophorectomy group when compared to the historical control (54 years) (P =.012). The proportion of synchronous metastasis was higher in the oophorectomy than the control group (57% vs 30%, respectively; P=.003). After a median follow-up duration of 60.8 months (range, 7.4 - 169.7 months), the median OS was significantly longer in the oophorectomy group (28.1 vs 21.2 months, oophorectomy vs non-oophoreectomy; P=.038). For ovary-specific survival (date of ovarian metastasis diagnosis to death), colorectal cancer patients with oophorectomy showed significantly favorable survival than the control group (20.8 vs 10.9 months, respectively; P<.001). At univariate analyses, no oophorectomy (P=.038), bilaterality of ovarian metastasis (P=0.032), the presence of extraovarian metastasis (P<0.001), elevated CEA (p<0.001), poor performance status (p=0.001), no palliative chemotherapy(p=0.001), no primary disease resection(p=0.005) were identified as significantly poor prognostic factors for overall survival. The no oophorectomy, no chemotherapy, extraovarian metastasis, elevated CEA, poor performance status retained statistical significance at multivariate level. (p=0.003, p=0.004, p=0.005, p=0.015, p=0.029, respectively). Conclusions: Based on this retrospective analysis, the oophorectomy significantly prolonged survival in colorectal cancer patients with ovarian metastases. A potential role of oophorectomy in the management of colorectal cancer should be prospectively studied.

No significant financial relationships to disclose.

Efficient taste and odour removal by water treatment plants around the Han River water supply system

Seven major water treatment plants in Seoul Metropolitan Area, which are under Korea Water Resources Corporation (KOWACO)'s management, take water from the Paldang Reservoir in the Han River System for drinking water supply. There are taste and odour (T&O) problems in the finished water because the conventional treatment processes do not efficiently remove the T&O compounds. This study evaluated T&O removal by ozonation, granular activated carbon (GAC) treatment, powder activated carbon (PAC) and an advanced oxidation process in a pilot-scale treatment plant and bench-scale laboratory experiments. During T&O episodes, PAC alone was not adequate, but as a pretreatment together with GAC it could be a useful option. The optimal range of ozone dose was 1 to 2 mg/L at a contact time of 10 min. However, with ozone alone it was difficult to meet the T&O target of 3 TON and 15 ng/L of MIB or geosmin. The GAC adsorption capacity for DOC in the three GAC systems (F/A, GAC and O3 + GAC) at an EBCT of 14 min is mostly exhausted after 9 months. However, substantial TON removal continued for more than 2 years (>90,000 bed volumes). GAC was found to be effective for T&O control and the main removal mechanisms were adsorption capacity and biodegradation.

Risk factors for low bone mineral density (BMD) in pediatric sarcoma survivors

9059

Background: The incidence of and risk factors for low BMD in patients treated for sarcoma in childhood is unknown. Methods: Retrospective medical record review of 99 patients with pediatric sarcoma diagnosed between 12/82 and 2/03 who had undergone QCT evaluation more than 1 year after completion of treatment. Low BMD was defined as >1.5 standard deviations below the mean. A Z-test was used to assess whether BMD was lower in our patient population than in the normal reference population. Logistic regression was used to examine factors predictive of low BMD. Risk factors analyzed included demographic variables, tumor features, treatment exposures, endocrine/renal dysfunction, and health habits. Results: Twenty-six of the 99 sarcoma survivors (26%) had low BMD. The mean (−0.8) and median (−0.75) QCT Z-scores were significantly lower than those of the normal reference population (mean and median = 0, p<0.0001). Factors associated with lower BMD included young age at sarcoma diagnosis (p=0.044) or at QCT measurement (p=0.001), greater weight at diagnosis (p=0.045), non-lower extremity tumor site (p=0.023), higher cumulative cyclophosphamide dose (p=0.007), smaller size at QCT measurement [height (p=0.018), weight (p=0.012)], and low serum creatinine [at diagnosis (p=0.033), at QCT measurement (p=0.014)]. Gender, race, ifosfamide/methotrexate/etoposide exposure, radiotherapy, endocrinopathy, and health habits were not predictive of low BMD. Conclusions: Survivors of childhood sarcoma are at high risk for low BMD. Risk factors include young age, non-lower extremity tumor site, and high cumulative cyclophosphamide exposure. Prospective studies are needed to confirm these risk factors, and to guide implementation of effective screening guidelines and therapeutic measures.

No significant financial relationships to disclose.

Decision threshold adjustment in class prediction

Standard classification algorithms are generally designed to maximize the number of correct predictions (concordance). The criterion of maximizing the concordance may not be appropriate in certain applications. In practice, some applications may emphasize high sensitivity (e.g., clinical diagnostic tests) and others may emphasize high specificity (e.g., epidemiology screening studies). This paper considers effects of the decision threshold on sensitivity, specificity, and concordance for four classification methods: logistic regression, classification tree, Fisher's linear discriminant analysis, and a weighted k-nearest neighbor. We investigated the use of decision threshold adjustment to improve performance of either sensitivity or specificity of a classifier under specific conditions. We conducted a Monte Carlo simulation showing that as the decision threshold increases, the sensitivity decreases and the specificity increases; but, the concordance values in an interval around the maximum concordance are similar. For specified sensitivity and specificity levels, an optimal decision threshold might be determined in an interval around the maximum concordance that meets the specified requirement. Three example data sets were analyzed for illustrations.

Absolute frequency measurement of rubidium 5S-7S two-photon transitions with a femtosecond laser comb

The absolute frequencies of rubidium 5S-7S two-photon transitions at 760 nm are measured to an accuracy of 20 kHz with an optical frequency comb based on a mode-locked femtosecond Ti:sapphire laser. The rubidium 5S-7S two-photon transitions are potential candidates for frequency standards and serve as important optical frequency standards for telecommunication applications. The accuracy of the hyperfine constant of the 7S1/2 state is improved by a factor of 5 in comparison with previous results.

Diode-laser frequency stabilization by two-frequency Doppler-broadened absorption spectroscopy

We demonstrate a robust method for frequency stabilization of a diode laser by two Doppler-broadened absorption spectra of the cesium D2 line. This technique employs an acousto-optical modulator to generate another frequency component from a diode laser to perform the spectroscopy. The 852-nm diode laser with frequency stabilization at the zero crossing of the error signal showed a peak-to-peak fluctuation of 800 kHz compared with a frequency-stabilized femtosecond laser over a 2-h period. This frequency-locking method is free of modulation and can be applied to frequency discriminators as well as to atomic resonances.

The Seoul Metropolitan Preschool Vision Screening Programme: results from South Korea

AIM

To report on a new model of preschool vision screening that was performed in metropolitan Seoul and to investigate the distribution of various ocular disorders in this metropolitan preschool population.

METHODS

Vision screening was conducted on 36 973 kindergarten children aged 3-5 years in a stepwise manner. The first step was home screening using a set of five picture cards and a questionnaire. The children who did not pass the first step (VA <0.5 in at least one eye or any abnormal responses on the questionnaire) were retested with regular vision charts at the regional public healthcare centres. After this retest, some children were referred to ophthalmologists. The referral criteria for visual acuity were <0.5 at 3 years and <0.63 at 4 or 5 years in at least one eye.

RESULTS

Of those screened, 7116 (19.2%) children did not pass the home screening tests and 2058 (28.9%) out of the 7116 were referred. The results of the ophthalmological examination in eye clinics were only available for 894 children (43.4%) of those who were referred. The rest of the children did not visit ophthalmologists because they had been checked at an eye clinic, were currently under treatment, or for personal reasons. Refractive errors were found in 608 (1.6%) children. Astigmatism was associated in 78.2% of ametropes. Amblyopia was discovered in 149 (0.4%) children and refractive error was the major aetiology with a predominant rate (82.5%). Manifest strabismus was detected in 52 children. The positive predictive value of vision screening for any ophthalmological disorder was 0.77, and 0.49 for significant disorders requiring treatment.

CONCLUSIONS

This preschool vision screening model was highly accessible to the children and their parents, easy to administer, and effective to detect a variety of ocular disorders. However, the participation rate of the referred children in the examinations by ophthalmologists was quite low. The performance and efficiency of this screening programme need to be optimised with further revision.