Contribution of refractive errors to visual impairment in patients at korle-bu teaching hospital

Objective: To determine the contribution of refractive error to visual impairment in visually impaired patients attending Korle-Bu Teaching Hospital, Ghana. Method: This study was conducted over a periodof 1 year beginning October 2002 at Korle-Bu Teaching Hospital. Every 4th consecutive new case attending the eye clinic, aged 6 years andabove was selected and interviewed using a structured questionnaire. A Snellen’s chart was used to determine the unaided visual acuity, visual acuity with spectacles where the patient was wearing one, and visual acuity with pin hole with or without spectacles. Improvement in visual acuity by 2 or more lines on the Snellen’s chart when lookingthrough the pin hole was regarded as an indication of refractive error.Results: A total of 1,069 respondents, 594 female and 475 male were recruited into the study. One hundred and fifteen (115) patients (10.76%) were found to have impaired vision (Visual acuityworse than 6/18 to PL in the better eye). The vision of 51 of those with impaired vision improved when looking through the pin hole. Refractive error with Visual Acuity worse than 6/18 was present in 4.8% of all patients who attended the eye clinic. Refractive error was present in 44.3% of patients with visual impairment. Conclusion: Visual impairment was a common presentation and uncorrected refractive error was a major cause of visual impairment

A framework for evaluating the impact of communication on performance in large-scale distributed urban simulations

A primary motivation for employing distributed simulation is to enable the execution of large-scale simulation workloads that cannot be handled by the resources of a single stand-alone computing node. To make execution possible, the workload is distributed among multiple computing nodes connected to one another via a communication network. The execution of a distributed simulation involves alternating phases of computation and communication to coordinate the co-operating nodes and ensure correctness of the resulting simulation outputs. Reliably estimating the execution performance of a distributed simulation can be difficult due to non-deterministic execution paths involved in alternating computation and communication operations. However, performance estimates are useful as a guide for the simulation time that can be expected when using a given set of computing resources. Performance estimates can support decisions to commit time and resources to running distributed simulations, especially where significant amounts of funds or computing resources are necessary. Various performance estimation approaches are employed in the distributed computing literature, including the influential Bulk Synchronous Parallel (BSP) and LogP models. Different approaches make various assumptions that render them more suitable for some applications than for others. Actual performance depends on characteristics inherent to each distributed simulation application. An important aspect of these individual characteristics is the dynamic relationship between the communication and computation phases of the distributed simulation application. This work develops a framework for estimating the performance of distributed simulation applications, focusing mainly on aspects relevant to the dynamic relationship between communication and computation during distributed simulation execution. The framework proposes a meta-simulation approach based on the Multi-Agent Simulation (MAS) paradigm. Using the approach proposed by the framework, meta-simulations can be developed to investigate the performance of specific distributed simulation applications. The proposed approach enables the ability to compare various what-if scenarios. This ability is useful for comparing the effects of various parameters and strategies such as the number of computing nodes, the communication strategy, and the workload-distribution strategy. The proposed meta-simulation approach can also aid a search for optimal parameters and strategies for specific distributed simulation applications. The framework is demonstrated by implementing a meta-simulation which is based on case studies from the Urban Simulation domain

Heuristic performance on inventory routing with logistic ratio

The inventory routing problem (IRP) is a hard combinatorial optimization problem, where a supplier is responsible for maintaining the inventory levels of customers to keep them from running out of product, while maintaining low overall delivery costs. The IRP involves routing and scheduling decisions, and the search space grows exponentially with problem size. Although most of the IRP literature focuses on the objective of minimizing delivery costs over a planning horizon, the logistic ratio (delivery cost per unit of product) has been identified in some studies on real-life companies as a potentially better measure of cost efficiency. This study compares the long term cost difference between optimizing cost and optimizing the logistic ratio by running a series of computational experiments. From the results, it emerges that although optimizing the logistic ratio is indeed beneficial in many cases, optimizing cost may be better in the long term for some problem instances, particularly those with short planning horizon

A framework for evaluating the impact of communication on performance in large-scale distributed urban simulations

A primary motivation for employing distributed simulation is to enable the execution of large-scale simulation workloads that cannot be handled by the resources of a single stand-alone computing node. To make execution possible, the workload is distributed among multiple computing nodes connected to one another via a communication network. The execution of a distributed simulation involves alternating phases of computation and communication to coordinate the co-operating nodes and ensure correctness of the resulting simulation outputs. Reliably estimating the execution performance of a distributed simulation can be difficult due to non-deterministic execution paths involved in alternating computation and communication operations. However, performance estimates are useful as a guide for the simulation time that can be expected when using a given set of computing resources. Performance estimates can support decisions to commit time and resources to running distributed simulations, especially where significant amounts of funds or computing resources are necessary. Various performance estimation approaches are employed in the distributed computing literature, including the influential Bulk Synchronous Parallel (BSP) and LogP models. Different approaches make various assumptions that render them more suitable for some applications than for others. Actual performance depends on characteristics inherent to each distributed simulation application. An important aspect of these individual characteristics is the dynamic relationship between the communication and computation phases of the distributed simulation application. This work develops a framework for estimating the performance of distributed simulation applications, focusing mainly on aspects relevant to the dynamic relationship between communication and computation during distributed simulation execution. The framework proposes a meta-simulation approach based on the Multi-Agent Simulation (MAS) paradigm. Using the approach proposed by the framework, meta-simulations can be developed to investigate the performance of specific distributed simulation applications. The proposed approach enables the ability to compare various what-if scenarios. This ability is useful for comparing the effects of various parameters and strategies such as the number of computing nodes, the communication strategy, and the workload-distribution strategy. The proposed meta-simulation approach can also aid a search for optimal parameters and strategies for specific distributed simulation applications. The framework is demonstrated by implementing a meta-simulation which is based on case studies from the Urban Simulation domain

Dermis-fat grafts and enucleation in Ghanaian children: 5 years’ experience

Background: Enucleation in young children often results in retarded orbital growth ipsilaterally. The need for an implant that will naturally grow with the child, like Dermis-fat Graft (DFG), for managing the anophthalmia has been of interest over the years.Objective: To evaluate the use of DFG as an implant for volume replacement post-enucleation.Study Design: A prospective non-comparative case series involving 18 consecutive children who had DFG either primarily or secondarily in  conjunction with enucleation for intraocular pathologies, from December2007 to September 2012, at the ophthalmology unit, Korle-Bu. Data from patients who had a minimum of three months follow up(FUP) were analysed.Outcome measures: Complete covering of DFG with healthy conjunctiva, increase in volume of DFG, and presence or absence of   complications.Results: Fifteen patients were analysed, aged nine months to ten years (mean (SD), 3.7±2.7years). Eight (53.3%) were females. Thirteen (86.7%) DFGs were secondary and 2(13.3%) primary. Indications for enucleationwere intraocular retinoblastoma (n=10, 66.7%), unexplained retinal detachment mimicking retinoblastoma (n=3,20.0%), anterior staphyloma(n=1,6.7%) and medulloepithelioma (n=1,6.7%). Fourteen (93.3%) patients showed increase in volume of DFG. Time for Conjunctival  reepithelialisation of the dermal surface was four to fourteen weeks(mean/median=5.5/4.0). Complications encountered were infection (n=1,6.7%), infection with necrosis (n=1,6.7%), melanosis /keratinization (n=2, 13.3%) and cysts(n=2,13.3%). The patients were followed upfor 3 to 54 months (mean/median 20.13 /16.00).Conclusion: DFG for management of post-enucleation anophthalmia in Ghanaian children showed 93.3% success. Keywords: Dermis- fat graft, enucleation, volume replacement,anophthalmi

Epidemiology and recurrence rate of pterygium post excision in Ghanaians

Objectives: To determine the epidemiology and recurrence rate of pterygium after excision using bare sclera techniqueDesign: Prospective non-comparative study.Setting: Ophthalmology unit, Korle-Bu Teaching Hospital, Accra, Ghana.Methods: The study involved 60 consecutive patients with primary apterygial from July 1998 to December 2000 who had bare sclera excision after informed consent. They were post-operatively followed up for 30-months.Results: Thirty-five patients (58%) were females. The patients' ages ranged from 17-75 years, mean (±12.6). Overall recurrence was 22(37%). The main complications encountered include were granuloma 20 %( n=12), restriction in medial rectus muscle motility 2(3%), persistent vascularisation at excision site 2(3%) and adherence leucoma with uveitis 1(2%). No significant association was found between recurrence and pterygium morphology, calcification, allergy and occupation (indoor or outdoor).Conclusion: The recurrence rate after pterygium excision using bare sclera technique in Ghanaians is high (37%).Keywords: Pterygium, epidemiology, bare sclera excision, recurrence, conjunctival growth

A prospective trial of postoperative Lodoxamide (Alomide) on pterygium recurrence

Background: To compare pterygium recurrence after bare sclera excision with and without topical lodoxamide.Design: Randomised double-blind study.Methods: The study involved 61 patients with primary pterygia who had bare sclera excision after informed consent. They were post-operatively treated by either of 2 treatment groups for 4 weeks, with a 30-months follow-up: Controls/placebo = Guttae prednisolone 1% with chloramphenicol 0.5% plus guttae distilled water. Test group = Guttae prednisolone 1% with chloramphenicol 0.5% plus guttae lodoxamide 0.1%.Results: Sixty patients were analysed. Control Group had 20 females and 10 males, aged 28-69.5 years, mean 42.0(± 10.9). Test Group had 15 males and 15 females, aged 17-75 years, mean 46.0(±12.6). Recurrence for the Test Group was 11(37%) within 30 months and 11(37%) for the Control Group within 30 months (OR=1.00, CI: 0.35-2.858). Main complications encountered were granuloma: 7(11.7%) from the controls and 5(8.3%) from the test group; restriction in the motility of medial rectus muscle: 1(1.7%) from each group; persistent vascularisation at site of excision: 1(1.7%) from each group and adherence leukoma with uveitis 1(1.7%) from the control group, the latter also had persistent peripheral corneal epithelial defect later resulting in a dellen. No significant difference was found between the treatment groups with respect to recurrence, type and time of complications, orientation and morphology of pterygium, P>0.05.Conclusion: The recurrence of pterygium is high (about one third) with or without the use of adjuvant lodoxamide.Keywords: Pterygium, epidemiology, bare sclera, Lodoxamide (Alomide), recurrence

Presentation of retinoblastoma at a paediatric eye clinic in Ghana

Background: Retinobalstoma, the commonest childhood malignant intraocular tumour, is usually diagnosed early with over 90% survival rate indeveloped countries. In developing countries, the diagnosis is late resulting in less than 50% survival.Objective: To determine retinoblastoma stages at presentation and patients¡¦ outcomes.Design: Retrospective case series.Methods: The clinical and histopathological records of children with retinoblastoma seen from May 2004 to December 2005 were studied. Data was analysed for mode of presentation, laterality, clinical staging usingReese-Ellsworth (R-E) classification, histopathological high risk features (HHRF) for metastasis, and patient outcome.Setting: Ophthalmology Unit, Korle-Bu Teaching Hospital, Ghana.Results: Twenty-three patients presented with retinoblastoma over the period. Males were 12(52.2%). The age range from 1 to 84 months, mean 36.3(„b22.15) and median (36 months). Nineteen (82.6%) hadunilateral and 4(17.4%) bilateral disease. The common clinical presentations were leukocoria in 20(87.0%), proptosis 8(34.8%), strabismus 5(21.7%) and red eye 5(21.7%). The clinical features were commensurate with R-E stage V in 20(87.0%) patients, 2(8.7%) withorbital recurrence and 1(4.3%) with post-enucleation anophthalmos. HHRFs were present in 9(75%) enucleated eyes with invasion of optic nerve as thecommonest site (7/9). The patients were followed up for 1 day to 19 months. Eight abandoned treatment, 2 were discharged for palliative treatment, 2 out of 5 with metastasis died and 6 had no metastases at their last visit. Common sites for metastasis were the bonemarrow, brain and orbit.Conclusion: Majority of the patients presented with advanced disease manifesting as leukocoria, proptosis, RE stages V disease and poor outcome

Retinopathy in severe malaria in Ghanaian children - overlap between fundus changes in cerebral and non-cerebral malaria

<p>Abstract</p> <p>Background</p> <p>In malaria-endemic areas, reliably establishing parasitaemia for diagnosis of malaria can be difficult. A retinopathy with some features unique to severe malaria with a predictive value on prognosis, has been described. Detection of this retinopathy could be a useful diagnostic tool. This study was designed to determine the diagnostic usefulness of retinopathy on ophthalmoscopy in severe malaria syndromes: Cerebral malaria (CM) and non-cerebral severe malaria (non-CM), i.e. malaria with respiratory distress (RD) and malaria with severe anaemia (SA), in Ghanaian children. Secondly, to determine any association between retinopathy and the occurrence of convulsions in patients with CM.</p> <p>Methods and subjects</p> <p>A cross-sectional study of consecutive patients on admission with severe malaria who were assessed for retinal signs, at the Department of Child Health, Korle-Bu Teaching Hospital, Accra, from July to August 2002 was done. All children had dilated-fundus examination by direct and indirect ophthalmoscopy.</p> <p>Results</p> <p>Fifty-eight children aged between six months and nine years were recruited. Twenty six(45%) had CM, 22 with convulsion; 26(45%) had SA and six(10%) had RD.</p> <p>Any retinopathy was seen in: CM 19(73%), SA 14(54%), RD 3(50.0%), CM with convulsion 15(68%) and CM without convulsion 4(100%). Comparison between CM versus non-CM groups showed a significant risk relationship between retinal whitening and CM(OR = 11.0, CI = 2.2- 56.1, p = 0.001). There was no significant association with papilloedema(OR = 0.9, CI = 0.3 - 3.0, p = 0.9), macular whitening(OR = 1.6, CI = 0.5 - 4.8, p = 0.4), macular haemorrhage(OR = 0.28, CI = 0.03 - 2.7 p = 0.2), retinal haemorrhage(OR = 1.9, CI = 0.6 - 5.6, p = 0.3), vessel abnormality(OR = 1.9, CI = 0.6 - 6.1, p = 0.3) and cotton wool spots(OR not calculated, p = 0.08).</p> <p>Tortuous and engorged retinal veins, not previously described as a feature of CM, was the most common vascular abnormality(15/58 = 26%) and was detected even in the absence of papilloedema.</p> <p>Conclusion</p> <p>Retinal whitening, a sign suggestive of retinal ischaemia, was significantly more common in CM than in non-CM syndromes. However, the high prevalence of any retinopathy in the latter suggests that the brain and the retina may be suffering from ischaemia in both CM and non-CM.</p

The clinical characteristics of patients with glaucoma presenting to Botswana healthcare facilities: an observational study

Objective This study aimed to establish the clinical characteristics of patients with glaucoma attending eye care facilities in Botswana, and management of glaucoma among patients who received care in these facilities. The study also aimed to calculate the number of new diagnoses of glaucoma within the glaucoma service. Design A prospective, hospital-based, observational study. Setting A multicentre study was undertaken in government-run eye departments in Botswana from June to August 2012. Participants All patients with a diagnosis of glaucoma attending clinics at seven study sites were invited to participate. Outcome measures Examination findings, diagnosis and management were extracted from individual patient-held medical charts. Sociodemographic characteristics, patient knowledge and understanding of glaucoma were assessed through face-to-face interviews. In addition, details of outpatient attendances for 2011 were collected from 21 government-run hospitals. Results The majority of the 366 patients interviewed had a diagnosis of primary glaucoma (86.6%). The diagnoses were mainly made by ophthalmologists (48.6%) and ophthalmic nurses (44.0%). Many patients (38.5%) had been symptomatic for over 6 months before visiting an eye clinic. The mean presenting intraocular pressure was 28.2 mm Hg (SD 11.9 mm Hg). Most follow-up patients (79.2%) had not received surgery, however, many (89.5%) would accept surgery. Only 11.5% of participants had heard of glaucoma prior to diagnosis. Many participants (35.9%) did not understand glaucoma after being diagnosed. The majority (94.9%) of living first-degree relatives had never been examined. The number of newly diagnosed glaucoma cases for 2011 in the south of the country was 14.1/100 000; 95% CI (12.0 to 16.5), in the north it was 16.2/100 000; 95% CI (13.8 to 19.0). Conclusions Glaucoma is a significant burden that presents challenges to ophthalmic services in Botswana. Many patients have limited understanding of the condition and poor access to services. There is a need to develop a treatment infrastructure to include safe surgery and a reliable supply of effective medication