Shyamanga Borooah

Human iPSC-derived motoneurons harbouring TARDBP or C9ORF72 ALS mutations are dysfunctional despite maintaining viability

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease for which a greater understanding of early disease mechanisms is needed to reveal novel therapeutic targets. We report the use of human induced pluripotent stem cell (iPSC)-derived motoneurons (MNs) to study the pathophysiology of ALS. We demonstrate that MNs derived from iPSCs obtained from healthy individuals or patients harbouring TARDBP or C9ORF72 ALS-causing mutations are able to develop appropriate physiological properties. However, patient iPSC-derived MNs, independent of genotype, display an initial hyperexcitability followed by progressive loss of action potential output and synaptic activity. This loss of functional output reflects a progressive decrease in voltage-activated Na+ and K+ currents, which occurs in the absence of overt changes in cell viability. These data implicate early dysfunction or loss of ion channels as a convergent point that may contribute to the initiation of downstream degenerative pathways that ultimately lead to MN loss in ALS.

Floppy iris behaviour during cataract surgery: associations and variations

Aim: To assess the association of floppy iris behaviour during cataract surgery with use of α-1-antagonists and diabetes mellitus. Methods: 1842 eyes of 1786 patients undergoing phacohoemulsification surgery were prospectively enrolled. The use of commonly prescribed α-1-antagonists and the presence or absence of diabetes mellitus were noted. The occurrence of any of the features of the intraoperative floppy iris syndrome (IFIS) was noted by surgeons blinded to the patient’s history. Results: 57% of patients receiving tamsulosin showed features of IFIS compared with 1% of the non-tamsulosin group (p<0.001). Of these, more than half the patients manifested the syndrome in an incomplete form. Only 1 of the 51 patients receiving other α-1-antagonists had IFIS. Diabetes was also not associated with IFIS (p = 1). Conclusions: Tamsulosin is significantly associated with floppy iris behaviour during cataract surgery. But not all of these patients will necessarily show all or any features of IFIS. The floppy iris syndrome is likely to represent a continuum of severity. Various undefined factors, diabetes not being one of them, may have a contributory role. Non-selective α-1-antagonists are unlikely to be associated with IFIS.

Using human induced pluripotent stem cells to treat retinal disease

The eye is an ideal target for exploiting the potential of human induced pluripotent stem cell (hiPSC) technology in order to understand disease pathways and explore novel therapeutic strategies for inherited retinal disease. The aim of this article is to map the pathway from state-of-the art laboratory-based discoveries to realising the translational potential of this emerging technique. We describe the relevance and routes to establishing hiPSCs in selected models of human retinal disease. Additionally, we define pathways for applying hiPSC technology in treating currently incurable, progressive and blinding retinal disease.

Transorbital Sonographic Evaluation of Normal Optic Nerve Sheath Diameter in Healthy Volunteers in Bangladesh

Introduction Measurement of optic nerve sheath diameter (ONSD) by ultrasound is increasingly used as a marker to detect raised intracranial pressure (ICP). ONSD varies with age and there is no clear consensus between studies for an upper limit of normal. Knowledge of normal ONSD in a healthy population is essential to interpret this measurement. Methods In a prospective observational study, ONSD was measured using a 15 MHz ultrasound probe in healthy volunteers in Chittagong, Bangladesh. The aims were to determine the normal range of ONSD in healthy Bangladeshi adults and children, compare measurements in males and females, horizontal and vertical beam orientations and left and right eyes in the same individual and to determine whether ONSD varies with head circumference independent of age. Results 136 subjects were enrolled, 12.5% of whom were age 16 or under. Median ONSD was 4.41 mm with 95% of subjects in the range 4.25–4.75 mm. ONSD was bimodally distributed. There was no relationship between ONSD and age (≥4 years), gender, head circumference, and no difference in left vs right eye or horizontal vs vertical beam. Conclusions Ultrasonographic ONSD in Bangladeshi healthy volunteers has a narrow bimodal distribution independent of age (≥4 years), gender and head circumference. ONSD >4.75 mm in this population should be considered abnormal.

Late-onset retinal macular degeneration: clinical insights into an inherited retinal degeneration

AIM This study describes, in detail, the phenotype of late-onset retinal macular degeneration (L-ORMD) an inherited condition affecting both the retina and anterior segment. A staging based on clinical characteristics is proposed, and the relevance of this condition to current understanding of age-related macular degeneration is discussed. METHODS A systematic review of the literature regarding this condition supports a detailed description of the natural history. Clinical experiences in identifying, monitoring and managing patients are also presented. RESULTS L-ORMD is a rare fully penetrant autosomal dominant condition resulting from a mutation in the C1QTNF5 gene on chromosome 11. Affected individuals develop bilateral loss of vision, dark-adaptation abnormalities, fundus drusen-like yellow spots, midperipheral pigmentation, choroidal neovascularisation, chorioretinal atrophy and long anteriorly inserted lens zonules. Patients may benefit from treatment with high-dose vitamin A. CONCLUSIONS Raised awareness of L-ORMD should lead to earlier diagnosis and improved care for patients. New antivascular endothelial growth factor treatment may provide a new possibility for management. A deeper insight into molecular and genetic mechanisms of L-ORMD may suggest avenues to explore new treatments of this disorder.Aim: This study describes, in detail, the phenotype of late-onset retinal macular degeneration (L-ORMD) an inherited condition affecting both the retina and anterior segment. A staging based on clinical characteristics is proposed, and the relevance of this condition to current understanding of age-related macular degeneration is discussed. Methods: A systematic review of the literature regarding this condition supports a detailed description of the natural history. Clinical experiences in identifying, monitoring and managing patients are also presented. Results: L-ORMD is a rare fully penetrant autosomal dominant condition resulting from a mutation in the C1QTNF5 gene on chromosome 11. Affected individuals develop bilateral loss of vision, dark-adaptation abnormalities, fundus drusen-like yellow spots, midperipheral pigmentation, choroidal neovascularisation, chorioretinal atrophy and long anteriorly inserted lens zonules. Patients may benefit from treatment with high-dose vitamin A. Conclusions: Raised awareness of L-ORMD should lead to earlier diagnosis and improved care for patients. New antivascular endothelial growth factor treatment may provide a new possibility for management. A deeper insight into molecular and genetic mechanisms of L-ORMD may suggest avenues to explore new treatments of this disorder.

Long-term visual acuity and the duration of macular detachment: findings from a prospective population-based study

Aim To report the long-term visual outcome of a multicentre prospectively recruited cohort of macula-off rhegmatogenous retinal detachments (RRD) Methods The Scottish retinal detachment study was a prospectively recruited study that recruited all incident cases of primary RRD in Scotland over a 2-year period (2007–2009). All patients with a macula-off RRD from four participating sites were invited for clinical examination at 6 weeks, 3 months, 6 months and 1 year after the initial surgery. Using a joinpoint model we estimated the effect of duration of macular detachment on final visual outcome. Results In total, there were 291 patients with macula-off RRD without pre-existing retinal disease who had successful repair after one operation. 65.9% achieved a final visual acuity (VA) of 0.48 logMAR(6/18). Our model identified two time points (day 8 (95% CI 3 to 15 days) and (day 21 (95% CI 6 to 26 days)) after which there was a statistically significant worsening in final VA. Conclusions Our study suggests that the majority of patients with macula-off RRD successfully repaired with one operation will achieve a VA of 6/18 or better at final follow-up. After 8 days of macular detachment, the final visual outcome may be adversely affected and, thus, operative repair within this period is desirable. Duration of macular detachment of ≤8 days demonstrated a continuing improvement in VA for up to 1 year, a finding which was not found in macula detachments of longer duration.

Real-time quantitative monitoring of hiPSC-based model of macular degeneration on Electric Cell-substrate Impedance Sensing microelectrodes.

Age-related macular degeneration (AMD) is the leading cause of blindness in the developed world. Humanized disease models are required to develop new therapies for currently incurable forms of AMD. In this work, a tissue-on-a-chip approach was developed through combining human induced pluripotent stem cells, Electric Cell–substrate Impedance Sensing (ECIS) and reproducible electrical wounding assays to model and quantitatively study AMD. Retinal Pigment Epithelium (RPE) cells generated from a patient with an inherited macular degeneration and from an unaffected sibling were used to test the model platform on which a reproducible electrical wounding assay was conducted to model RPE damage. First, a robust and reproducible real-time quantitative monitoring over a 25-day period demonstrated the establishment and maturation of RPE layers on the microelectrode arrays. A spatially controlled RPE layer damage that mimicked cell loss in AMD disease was then initiated. Post recovery, significant differences (P<0.01) in migration rates were found between case (8.6±0.46 μm/h) and control cell lines (10.69±0.21 μm/h). Quantitative data analysis suggested this was achieved due to lower cell–substrate adhesion in the control cell line. The ECIS cell–substrate adhesion parameter (α) was found to be 7.8±0.28 Ω1/2 cm for the case cell line and 6.5±0.15 Ω1/2 cm for the control. These findings were confirmed using cell adhesion biochemical assays. The developed disease model-on-a-chip is a powerful platform for translational studies with considerable potential to investigate novel therapies by enabling real-time, quantitative and reproducible patient-specific RPE cell repair studies.

Improving the cost-effectiveness of photographic screening for diabetic macular oedema: a prospective, multi-centre, UK study.

Background/aims Retinal screening programmes in England and Scotland have similar photographic grading schemes for background (non-proliferative) and proliferative diabetic retinopathy, but diverge over maculopathy. We looked for the most cost-effective method of identifying diabetic macular oedema from retinal photographs including the role of automated grading and optical coherence tomography, a technology that directly visualises oedema. Methods Patients from seven UK centres were recruited. The following features in at least one eye were required for enrolment: microaneurysms/dot haemorrhages or blot haemorrhages within one disc diameter, or exudates within one or two disc diameters of the centre of the macula. Subjects had optical coherence tomography and digital photography. Manual and automated grading schemes were evaluated. Costs and QALYs were modelled using microsimulation techniques. Results 3540 patients were recruited, 3170 were analysed. For diabetic macular oedema, Englands scheme had a sensitivity of 72.6% and specificity of 66.8%; Scotlands had a sensitivity of 59.5% and specificity of 79.0%. When applying a ceiling ratio of £30 000 per quality adjusted life years (QALY) gained, Scotlands scheme was preferred. Assuming automated grading could be implemented without increasing grading costs, automation produced a greater number of QALYS for a lower cost than Englands scheme, but was not cost effective, at the studys operating point, compared with Scotlands. The addition of optical coherence tomography, to each scheme, resulted in cost savings without reducing health benefits. Conclusions Retinal screening programmes in the UK should reconsider the screening pathway to make best use of existing and new technologies.

Improving the economic value of photographic screening for optical coherence tomography-detectable macular oedema: a prospective, multicentre, UK study

OBJECTIVES To determine the best photographic surrogate markers for detecting sight-threatening macular oedema (MO) in people with diabetes attending UK national screening programmes. DESIGN A multicentre, prospective, observational cohort study of 3170 patients with photographic signs of diabetic retinopathy visible within the macular region [exudates within two disc diameters, microaneurysms/dot haemorrhages (M/DHs) and blot haemorrhages (BHs)] who were recruited from seven study centres. SETTING All patients were recruited and imaged at one of seven study centres in Aberdeen, Birmingham, Dundee, Dunfermline, Edinburgh, Liverpool and Oxford. PARTICIPANTS Subjects with features of diabetic retinopathy visible within the macular region attending one of seven diabetic retinal screening programmes. INTERVENTIONS Alternative referral criteria for suspected MO based on photographic surrogate markers; an optical coherence tomographic examination in addition to the standard digital retinal photograph. MAIN OUTCOME MEASURES (1) To determine the best method to detect sight-threatening MO in people with diabetes using photographic surrogate markers. (2) Sensitivity and specificity estimates to assess the costs and consequences of using alternative strategies. (3) Modelled long-term costs and quality-adjusted life-years (QALYs). RESULTS Prevalence of MO was strongly related to the presence of lesions and was roughly five times higher in subjects with exudates or BHs or more than two M/DHs within one disc diameter. Having worse visual acuity was associated with about a fivefold higher prevalence of MO. Current manual screening grading schemes that ignore visual acuity or the presence of M/DHs could be improved by taking these into account. Health service costs increase substantially with more sensitive/less specific strategies. A fully automated strategy, using the automated detection of patterns of photographic surrogate markers, is superior to all current manual grading schemes for detecting MO in people with diabetes. The addition of optical coherence tomography (OCT) to each strategy, prior to referral, results in a reduction in costs to the health service with no decrement in the number of MO cases detected. CONCLUSIONS Compared with all current manual grading schemes, for the same sensitivity, a fully automated strategy, using the automated detection of patterns of photographic surrogate markers, achieves a higher specificity for detecting MO in people with diabetes, especially if visual acuity is included in the automated strategy. Overall, costs to the health service are likely to increase if more sensitive referral strategies are adopted over more specific screening strategies for MO, for only very small gains in QALYs. The addition of OCT to each screening strategy, prior to referral, results in a reduction in costs to the health service with no decrement in the number of MO cases detected. STUDY REGISTRATION This study has been registered as REC/IRAS 07/S0801/107, UKCRN ID 9063 and NIHR HTA 06/402/49. SOURCE OF FUNDING This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 17, No. 51. See the HTA programme website for further project information.

Clinicopathological review of ocular surface squamous neoplasia in Malawi

Background Ocular surface squamous neoplasia (OSSN) is the most common cause of malignancy of the conjunctiva. Variable clinical presentation means that invasive malignant OSSN is often difficult to discriminate from other similarly presenting differential diagnoses which can be managed more conservatively. Aims Identification of clinical factors associated with a histopathological diagnosis of conjunctival squamous cell carcinoma (SCC). Methods Prospective consecutive case series of suspected OSSN cases presenting at two hospitals in Central Malawi over a 1 year period. A pro forma was completed assessing preidentified clinical variables. Suspected lesions underwent excisional biopsy followed by histopathological investigation. Results Fifty-eight patients were recruited. Mean age was 35.8 (range 22–62). 51 cases of histopathologically confirmed OSSN were found. 30 (50%) patients were confirmed HIV seropositive which rose to 86.67% in invasive SCC. Larger size of tumour (p=0.008), male gender (p=0.025) and HIV seropositivity (p=0.010) were associated with invasive SCC pathology. Conclusions A clinicopathological study of OSSN has not previously been performed in Malawi. The association of HIV with SCC corresponds to previous reports from sub-Saharan Africa. A new finding in our study is a relationship between larger tumour size and invasive lesions confirmed by histopathology. When integrated into a clinical decision-making model, tumour area provides a simple clinical measure for ophthalmic practitioners to use in order to differentiate higher risk OSSN from more benign pathology. The higher risk lesions can subsequently be treated with greater surgical care and undergo closer follow-up.