Moorfields Eye Hospital

About: Moorfields Eye Hospital is a healthcare organization based out in London, United Kingdom. It is known for research contribution in the topics: Visual acuity & Glaucoma. The organization has 3721 authors who have published 6790 publications receiving 246004 citations.

Clinical assessment of two new contrast sensitivity charts.

Abstract: Background: Contrast sensitivity measurement in UK clinical practice is most commonly performed with the Pelli–Robson chart. Aims: To compare the repeatability of two new contrast sensitivity charts and to measure their agreement with the Pelli–Robson charts. Method: Contrast sensitivity was measured monocularly using two versions of the Mars letter contrast sensitivity chart, two presentations on the Test Chart 2000 and two versions of the Pelli–Robson chart. Bland–Altman techniques were used to assess repeatability and agreement. Results: 53 subjects were recruited with visual acuity from 6/4 to 6/72. The coefficient of repeatability was 0.182 for the Pelli–Robson chart, 0.121 for the Mars chart and 0.238 for Test Chart 2000. Limits of agreement with the Pelli–Robson chart were −0.29 to +0.15 log units for the Mars letter contrast sensitivity chart and −0.32 to +0.78 log units for the Test Chart 2000. For patients with poor contrast sensitivity, the limits of agreement between the Test Chart 2000 and the Pelli–Robson chart improved from −0.33 to +0.15 log units. Conclusion: In a population of hospital ophthalmology patients, the coefficient of repeatability is better for the Mars chart and worse for the Test Chart 2000 when compared with the Pelli–Robson chart. The electronic test chart does not agree well with the Pelli–Robson chart, although this might simply be due to the performance of liquid crystal display screens at low contrast levels. The Mars letter contrast sensitivity chart shows good validity and reasonable agreement with the Pelli–Robson chart.

Epidemiology of Pseudomonas aeruginosa keratitis in contact lens wearers.

Abstract: This study evaluated the epidemiology of Pseudomonas aeruginosa keratitis in contact lens (CL) wearers; the relationships between CL storage case contamination and CL hygiene practice and between CL hygiene and the development of keratitis. Sixteen CL wearers with keratitis were compared with 44 asymptomatic controls. Lens hygiene practice was assessed and CL care materials, domestic water sites and endogenous sites were evaluated microbiologically. Poor CL hygiene was not associated with Ps. aeruginosa keratitis. There was an association between keratitis and bacterial contamination of the CL and storage case (P < 0.0005). Lens and storage case contamination were not significantly associated with poor hygiene. No domestic or endogenous source for Ps. aeruginosa was found. Causative organisms may be derived from other sources, but CLs and CL storage cases provide a favourable environment for Ps. aeruginosa colonization. Changing the CL care environment to one less favourable for Ps. aeruginosa may help to eliminate this problem.

Epidemiological characteristics, predisposing factors and microbiological profiles of infectious corneal ulcers: the Portsmouth corneal ulcer study

Abstract: Aim: The aim of the study was to identify the epidemiological characteristics, predisposing factors, and the clinical and microbiological diagnosis of infectious corneal ulcers in a population based in southern England. Methods: A retrospective review was undertaken of the medical records of patients presenting with infectious corneal ulcers at the eye casualty department of Queen Alexandra Hospital, Portsmouth, UK, between January 1997 and December 2003. Results: A total of 1786 patients presented with infectious corneal ulcers, with a mean age of 45 years and female predominance (54.5%). Contact lens wear was the main predisposing factor in 554 patients (31%). Corneal scrapes from 1254 patients grew positive cultures in 800 patients. Gram-positive bacteria accounted for 696 (71.1%) of the total 979 bacterial isolates, while Gram-negative bacteria accounted for 283 (28.9%) with the predominance of Pseudomonas aeruginosa. Nine out of 11 patients with Acanthamoeba keratitis were contact lens wearers. The majority of patients 1728 (96.8%) sought medical help more than once and 34 patients (1.9%) had poor visual outcome. Follow-up was completed in 1633 patients (91.4%) with an average of 11.5 days. Conclusions: Wearing contact lenses remains the most important risk factor for infectious corneal ulcers. Reduction of the rate and severity of infectious keratitis requires continuous education of patients, and of professionals.

Mutations in REEP6 Cause Autosomal-Recessive Retinitis Pigmentosa

Abstract: Retinitis pigmentosa (RP) is the most frequent form of inherited retinal dystrophy. RP is genetically heterogeneous and the genes identified to date encode proteins involved in a wide range of functional pathways, including photoreceptor development, phototransduction, the retinoid cycle, cilia, and outer segment development. Here we report the identification of biallelic mutations in Receptor Expression Enhancer Protein 6 (REEP6) in seven individuals with autosomal-recessive RP from five unrelated families. REEP6 is a member of the REEP/Yop1 family of proteins that influence the structure of the endoplasmic reticulum but is relatively unstudied. The six variants identified include three frameshift variants, two missense variants, and a genomic rearrangement that disrupts exon 1. Human 3D organoid optic cups were used to investigate REEP6 expression and confirmed the expression of a retina-specific isoform REEP6.1, which is specifically affected by one of the frameshift mutations. Expression of the two missense variants (c.383C>T [p.Pro128Leu] and c.404T>C [p.Leu135Pro]) and the REEP6.1 frameshift mutant in cultured cells suggest that these changes destabilize the protein. Furthermore, CRISPR-Cas9-mediated gene editing was used to produce Reep6 knock-in mice with the p.Leu135Pro RP-associated variant identified in one RP-affected individual. The homozygous knock-in mice mimic the clinical phenotypes of RP, including progressive photoreceptor degeneration and dysfunction of the rod photoreceptors. Therefore, our study implicates REEP6 in retinal homeostasis and highlights a pathway previously uncharacterized in retinal dystrophy.

Detection of and Discrimination between Gram-Positive and Gram-Negative Bacteria in Intraocular Samples by Using Nested PCR

Abstract: A nested PCR protocol has been developed for the detection of and discrimination between 14 species of gram-positive and -negative bacteria in samples of ocular fluids. First-round PCR with pan-bacterial oligonucleotide primers, based on conserved sequences of the 16S ribosomal gene, was followed by a gram-negative-organism-specific PCR, which resulted in a single 985-bp amplification product, and a multiplex PCR which resulted in two PCR products: a 1,025 bp amplicon (all bacteria) and a 355 bp amplicon (gram-positive bacteria only). All products were detected by gel electrophoresis. The sensitivity of the assay was between 10 fg and 1 pg of bacterial DNA, depending on the species tested, equivalent to between 24 and 4 live bacteria spiked in water. The identification was complete in 3.5 h. The molecular techniques were subsequently applied to four samples of intraocular fluid, (three vitreous and one aqueous) from three patients with clinical signs of bacterial endophthalmitis (test samples) and two samples of vitreous from a patient with chronic intraocular inflammation (control samples). In all culture-positive samples (two of three vitreous and one of one aqueous), a complete concordance was observed between molecular methods and culture results. PCR correctly identified the gram stain classification of the organisms. The bacterial etiology was also identified in a culture-negative patient with clinical history and signs highly suggestive of bacterial endophthalmitis. Furthermore, control samples from a patient with chronic intraocular inflammation remained PCR negative. In summary, this protocol has demonstrated potential as a rapid diagnostic test in confirming the diagnosis of infection and also determining the Gram status of bacteria with high specificity and sensitivity.