D.A. H. Laidlaw

A Simple Model to Predict the Sensitivity to Change of Visual Acuity Measurements.

Background: Estimates of test-retest variability (TRV) in the form of a 95% range have been suggested as providing a cutoff value (or “change-criterion”) against which measured acuity changes can be judged to decide whether they are indicative of a clinically important change. This approach is based on ensuring that the specificity of the procedure is 95% in individuals with no real change. In an earlier article we investigated empirically the ability of the procedure to detect varying degrees of change (its sensitivity). In this article, we develop a simple statistical model to examine further the sensitivity of the approach. Methods. A statistical model was developed, and predictions from the model were compared with empirical visual acuity data. Results. The model predicts that for changes equal in size to the magnitude of the change-criterion, sensitivity will be 50%. For changes 1.65 times the change-criterion, sensitivity is 90% and increasing to 95% for changes 1.84 times the size of the change-criterion. Predicted sensitivities agreed well with those measured empirically. Conclusions. The 95% range for TRV is often used to decide whether measured changes are indicative of clinically important changes. Evaluating the performance of visual acuity charts using a method analogous to that of estimating the sensitivity and specificity of a screening test highlights some limitations of this method. Use of the 95% range as a change-criterion ensures a high specificity, but a simple statistical model indicates that changes must approach twice the size of the change-criterion before they will be detected with sensitivity in excess of 95%. This has implications for the clinician attempting to assess the reliability of visual acuity charts, and in other similar tests, to detect change.

Chronic postoperative fungal endophthalmitis caused by Penicillium citrinum after cataract surgery

An 85-year-old man developed chronic postoperative endophthalmitis after complicated cataract surgery. Visual acuity in the affected eye was hand movements. Slitlamp biomicroscopy showed a hypopyon, superonasal iris nodule, and marked vitritis. An anterior chamber washout, iris biopsy, and intravitreal amphotericin injection were performed. Panfungal polymerase chain reaction of anterior chamber and vitreous samples were positive for Penicillium citrinum. The iris biopsy showed hyphae on Grocott staining. Despite treatment, the patients acuity deteriorated to light perception and he developed severe intractable pain requiring evisceration. Histological analysis showed diffuse infiltration of hyphae. Penicillium species are fungal organisms that are ubiquitous in the environment and can cause chronic endophthalmitis. They are commonly dismissed as culture contaminants. True infection is confirmed by histological demonstration of fungal invasion. Diagnosis can be aided by iris biopsy if iris nodules are present. Polymerase chain reaction testing was beneficial in identifying the causative organism and should be considered early in endophthalmitis cases. Despite intravitreal and systemic antifungal treatment, the visual prognosis for this condition is variable. FINANCIAL DISCLOSURE None of the authors has a financial or proprietary interest in any material or method mentioned.

Vitreoretinal surgery on the fellow eye: A retrospective analysis of 18 years of surgical data from a tertiary center in England

Purpose: To determine the long-term incidence of fellow-eye surgical involvement in patients who have undergone first-eye vitreoretinal (VR) surgery for a variety of indications. This was a single-institution retrospective, consecutive series. Methods: Eighteen years of electronic surgical data were reviewed at our institution. All patients having surgery for the following indications were included: rhegmatogenous retinal detachment (RRD), macular hole (MH), epiretinal membrane (ERM), proliferative diabetic retinopathy (PDR), vitritis, and dropped nucleus. Primary outcome was the cumulative incidence of fellow-eye surgery at 10 years by Kaplan–Meier analysis. Results: Total follow-up was 29,629 patient-years. Cumulative incidence (± standard error) of fellow-eye surgery at 10 years was 7.2% ± 0.6% for RRD, 9.1% ± 1.3% for ERM, 7.5% ± 1.8% for MH, 30.6% ± 1.9% for PDR, 13.7% ± 2.9% for vitritis, and 2.8% ± 1.6% for dropped nuclei. The hazard for second-eye surgery was greatest in the early postoperative period after first-eye surgery for all indications. For RRD, the hazard was 2.7% ± 0.3% at year 1, 1.1% ± 0.2% at year 2, and 0.5% ± 0.2% at year 5. Risk factors for fellow-eye involvement for RRD were younger age (P < 0.001) and male gender (P < 0.01). Conclusion: We report the long-term risk of fellow-eye involvement in various VR pathologies, which is important in counseling patients regarding their risks as well as planning service provision.

Acute retinal detachment induced by the Valsalva manoeuvre in morning glory disc anomaly

We present a case in which a large, bullous, predominantly inferior, serous retinal detachment developed acutely after the Valsalva manoeuvre (from a coughing fit) in an eye with morning glory disc anomaly. We postulate that a rapid alteration in intracranial pressure was transmitted through the cavitary disc defect. This allowed a sudden influx of cerebrospinal fluid and/or liquefied vitreous into the subretinal space. This previously unreported case provides important evidence for the role of intracranial pressure fluctuations in the pathogenesis of macular schisis and neurosensory detachment secondary to optic disc cavitations.

Ethnic variation in vitreoretinal surgery: differences in clinical presentation and outcome.

Purpose The true prevalence of retinal detachment and other vitreoretinal disorders in different ethnic groups is not well-established. Understanding differences in vitreoretinal disease prevalence is important to appropriately allocate resources to meet demand where ethnic variation in the community exists. The aim of this study is to provide hospital-based data on the proportion of people with vitreoretinal disorders in the 3 main ethnic groups in the United Kingdom: Caucasian, Afro-Caribbean, and South Asian. Methods A retrospective study was performed on 3,262 patients undergoing vitreoretinal procedures for various indications between 2001 and 2014 from a single center in London, UK. Results The majority of patients with known ethnicity were Caucasian (80.19%) followed by Afro-Caribbean (12.31%) and Asian (5.20%). The mean age of the study population was 59.64 ± 15.75 years, with 57.28% males. Rhegmatogenous retinal detachment (RRD) was the common indication for surgery across all ethnic groups (54.83%). Caucasians were older, on average, compared to other ethnic groups at the time of surgery for RRD (p<0.05) and achieved higher success rates after primary surgery and were less likely to require silicone oil as primary tamponade. Macular hole was more common in the ethnic minorities with similar closure rates. Surgery for complications of diabetic retinopathy was more common in Afro-Caribbeans and Asians compared to Caucasians (28.07%, 24.02%, and 9.40%, p<0.05). Conclusions This study presents a large population-based data analysis on ethnic variation in vitreoretinal disorders. This may assist in predicting the requirement of vitreoretinal service provision depending on local ethnic variation.