New approaches to the diagnosis and management of microbial endophthalmitis

Endophthalmitis is a devastating ocular disease in which, despite adequate antibiotic cover, the final visual outcome for patients remains poor. In the search for other treatment modalities to aid in the management of these cases, the use of clarithromycin, as an anti-biofilm agent, was investigated. Results indicated that a greater number of culture negative cases demonstrated an improvement in vision of 6 Snellen lines when clarithromycin was used. In cases of presumed bacterial endophthalmitis, early diagnosis and appropriate treatment have been noted to be associated with a better visual outcome but currently, confirmation of the diagnosis of endophthalmitis (bacterial and / or fungal) is dependent on conventional techniques of microbiological isolation of organisms which require between 1-12 days. Furthermore, many samples prove to be culture negative. In this study, PCR technology has been successfully applied to the detection of bacteria and fungi in ocular samples from eyes with suspected endophthalmitis. Oligonucleotide primers based on the conserved sequences of the 16S rRNA gene (bacteria) and lanosterol 14 α-demethylase (Candida spp.), have been used to detect the presence of these pathogens. Restriction endonuclease digestion, DNA sequencing and cloning of the PCR product were used to enable species identification. Results demonstrated that PCR-based methods are able rapidly to confirm the presence of pathogens with high specificity and sensitivity. PCR based techniques have also been used to rule out with confidence the presence of pathogens, a unique advantage of this methodology. The use of molecular methods has significantly increased the number of intraocular samples from which a confirmed diagnosis is made and reduced the time to laboratory diagnosis. PCR based methods have demonstrated great potential in the rapid detection and identification of bacteria and Candida spp. in ocular samples and promise to provide a useful diagnostic tool for the future

The Risk of Sympathetic Ophthalmia Following Vitreoretinal Surgery

PURPOSE: To investigate the clinical course and the outcomes of sympathetic ophthalmia and correlate these with the nature of the inciting event and the number of vitreoretinal procedures undergone by patients. DESIGN: A retrospective case review. SUBJECTS: All patients diagnosed with sympathetic ophthalmia who have been treated or monitored at a single centre over a 15 year period. METHODS: A search of the electronic patient record system at Moorfields Eye Hospital, Londo over a 15 year period (between January 2000 and December 2015) was carried out, using the search terms "sympathetic", "ophthalmia" and "ophthalmitis". 61 patients with available records were identified and data collected from their complete electronic and paper records. MAIN OUTCOME MEASURES: The main outcome measures looked at were the best-corrected visual acuity (BCVA) at 1 year and at the end of follow up and the number of vitreoretinal surgical procedures preceding the diagnosis. Data was also collected to report on patient age, gender, disease duration, ocular and systemic manifestations, ocular complications, retinal angiography and treatment. RESULTS: There was a wide age range at presentation (2-84) and the length of follow up ranged 1-75 years. The first ocular event was trauma in 40 patients and surgery in 21. Vitreoretinal (VR) surgery accounted for 13 of the 21 surgical first event triggers (62%). 23/61 patients (38%) underwent VR surgery (1-7 operations) at some point prior to diagnosis. Surgical details were available for 15 patients, who had a total of 25 VR procedures carried out. Based on the surgical activity of the unit, the risk of developing SO following a single VR procedure is estimated at 0.008%, rising to 6.67% with 7 procedures. A total of 23 patients (38%) experienced a decrease in acuity at the end of the follow up period, versus 9 patients (15%) experiencing an improvement and 18 (30%) remaining unchanged. CONCLUSIONS: We feel that the most significant finding in this study is the calculated risk of SO development following a single VR procedure, which is significantly lower in our cohort than previously reported in the literature. This is seen to rise exponentially with additional procedures

Understanding Visual Impairment and Its Impact on Patients: A Simulation-Based Training in Undergraduate Medical Education

Introduction: Simulation activities are valuable teaching aids for understanding about living with visual impairment (VI). Our medical students used low-vision simulation spectacles (Sim-specs) to enable learning about VI. Methods: Students made tea and filled dosette boxes using Sim-specs simulating central visual loss (age-related macular degeneration) and navigated using Sim-specs simulating peripheral visual loss (glaucoma). Facilitators recorded errors made for each task. Students completed questionnaires to grade the tasks’ difficulty on a 4-point Likert-type scale. The students also participated in focus groups to discuss how their approach to working with patients may change following this training. Results: In total, 252 out of 254 students participated. Central visual loss provided the greatest challenge when undertaking fine motor skilled activity (dosette box). Highest average number of errors made was for dosette box task (0.70 error), followed by navigation (0.59), then making tea task (0.34). Students scored the most difficult task on average as the dosette box task (3.23 Likert-type points), followed by navigation (2.97), then making tea task (2.63). Our students have shown learning in recognising the challenges of VI and have adapted their approach to patients. Conclusions: Simulation activities are valuable additions to the undergraduate curriculum. Such activities can potentially enable greater empathy for our visually impaired patients

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

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

Inflammatory Vascular Disease

Henry Eales, a British ophthalmologist, described this condition almost 125 years ago [14, 15]. Eales’ original description was of recurring retinal and vitreous hemorrhages along with epistaxis, headaches, variation in peripheral circulation, dyspepsia, and chronic constipation in young men. He felt it was a vasomotor neurosis, wherein constriction of the alimentary vessels resulted in compensatory dilatation of the vessels in the head, leading to bleeding. Though Eales was honored with the eponym for this disease, Wadsworth was the first to describe the presence of retinal inflammation, 5 years later [37]. Duke Elder considered Eales’ disease to be a clinical manifestation of many diseases

Protocol for the Use of Polymerase Chain Reaction in the Detection of Intraocular Large B-Cell Lymphoma in Ocular Samples

To determine the usefulness of polymerase chain reaction (PCR) analyses in the diagnosis of lymphoid infiltrate cells in ocular samples, PCR was performed using oligonucleotide primers specific for immunoglobulin heavy chain rearrangement at framework 2, framework 3, and t(14;18) translocation of the bcl-2 gene. These were used to successfully generate amplicons of 220 to 230 bp, 110 to 120 bp, and 175 to 200 bp, respectively. After PCR amplification, primers directed against the t(14;18) detected 10 pg of B-cell lymphoma DNA. PCR against Fr2 and Fr3 IgH rearrangement detected 10 fg and 10 pg in the seminested PCR, respectively. Conventional pathological methods were highly accurate at establishing the correct final diagnosis in formalin-fixed, paraffin-embedded samples but were much less sensitive and predictive in cytological specimens of intraocular fluid. A combination of the three PCR reactions was an equally successful diagnostic approach on paraffin-embedded samples, whereas single PCR reactions did not significantly improve diagnosis over histopathological diagnostic techniques. Thus, a combination of PCR reactions is useful in the detection of B-cell monoclonality, aids the differentiation between lymphomatous and inflammatory infiltrates, and is more powerful as a diagnostic method than single PCR or conventional cytopathology for lymphoid infiltrates in ocular fluid aspirates