Systematic review of the agreement of tonometers with Goldmann applanation tonometry

OBJECTIVE: To assess the agreement of tonometers available for clinical practice with the Goldmann applanation tonometer (GAT), the most commonly accepted reference device.

DESIGN: A systematic review and meta-analysis of directly comparative studies assessing the agreement of 1 or more tonometers with the reference tonometer (GAT).

PARTICIPANTS: A total of 11 582 participants (15 525 eyes) were included.

METHODS: Summary 95% limits of agreement (LoA) were produced for each comparison.

MAIN OUTCOME MEASURES: Agreement, recordability, and reliability.

RESULTS: A total of 102 studies, including 130 paired comparisons, were included, representing 8 tonometers: dynamic contour tonometer, noncontact tonometer (NCT), ocular response analyzer, Ocuton S, handheld applanation tonometer (HAT), rebound tonometer, transpalpebral tonometer, and Tono-Pen. The agreement (95% limits) seemed to vary across tonometers: 0.2 mmHg (-3.8 to 4.3 mmHg) for the NCT to 2.7 mmHg (-4.1 to 9.6 mmHg) for the Ocuton S. The estimated proportion within 2 mmHg of the GAT ranged from 33% (Ocuton S) to 66% and 59% (NCT and HAT, respectively). Substantial inter- and intraobserver variability were observed for all tonometers.

CONCLUSIONS: The NCT and HAT seem to achieve a measurement closest to the GAT. However, there was substantial variability in measurements both within and between studies.

Perimetric progression in open angle glaucoma and the Visual Field Index (VFI)

PURPOSE: To evaluate the changes in the Visual Field Index (VFI) in eyes with perimetric glaucomatous progression, and to compare these against stable glaucoma patients.

PATIENTS AND METHODS: Consecutive patients with open angle glaucoma with a minimum of 6 reliable visual fields and 2 years of follow-up were identified. Perimetric progression was assessed by 4 masked glaucoma experts from different units, and classified into 3 categories: "definite progression," "suspected progression," or "no progression." This was compared with the Glaucoma Progression Analysis (GPA) II and VFI linear regression analysis, where progression was defined as a negative slope with significance of <5%.

RESULTS: Three hundred ninety-seven visual fields from 51 eyes of 39 patients were assessed. The mean number of visual fields was 7.8 (SD 1.1) per eye, and the mean follow-up duration was 63.7 (SD 13.4) months. The mean VFI linear regression slope showed an overall statistically significant difference (P<0.001, analysis of variance) for each category of progression. Using expert consensus opinion as the reference standard, both VFI analysis and GPA II had high specificity (0.93 and 0.90, respectively), but relatively low sensitivity (0.45 and 0.41, respectively).

CONCLUSIONS: The mean VFI regression slope in our cohort of eyes without perimetric progression showed a statistically significant difference compared with those with suspected and definite progression. VFI analysis and GPA II both had similarly high specificity but low sensitivity when compared with expert consensus opinion.

The effectiveness of early lens extraction with intraocular lens implantation for the treatment of primary angle-closure glaucoma (EAGLE): Study protocol for a randomized controlled trial

BACKGROUND: Glaucoma is the leading cause of irreversible blindness. Although primary open-angle glaucoma is more common, primary angle-closure glaucoma (PACG) is more likely to result in irreversible blindness. By 2020, 5·3 million people worldwide will be blind because of PACG. The current standard care for PACG is a stepped approach of a combination of laser iridotomy surgery (to open the drainage angle) and medical treatment (to reduce intraocular pressure). If these treatments fail, glaucoma surgery (eg, trabeculectomy) is indicated. It has been proposed that, because the lens of the eye plays a major role in the mechanisms leading to PACG, early clear lens extraction will improve glaucoma control by opening the drainage angle. This procedure might reduce the need for drugs and glaucoma surgery, maintain good visual acuity, and improve quality of life compared with standard care.EAGLE aims to evaluate whether early lens extraction improves patient-reported, clinical outcomes, and cost-effectiveness, compared with standard care.

METHODS/DESIGN: EAGLE is a multicentre pragmatic randomized trial. All people presenting to the recruitment centres in the UK and east Asia with newly diagnosed PACG and who are at least 50 years old are eligible.The primary outcomes are EQ-5D, intraocular pressure, and incremental cost per quality adjusted life year (QALY) gained. Other outcomes are: vision and glaucoma-specific patient-reported outcomes, visual acuity, visual field, angle closure, number of medications, additional surgery (e.g., trabeculectomy), costs to the health services and patients, and adverse events.A single main analysis will be done at the end of the trial, after three years of follow-up. The analysis will be based on all participants as randomized (intention to treat). 400 participants (200 in each group) will be recruited, to have 90% power at 5% significance level to detect a difference in EQ-5D score between the two groups of 0·05, and a mean difference in intraocular pressure of 1·75 mm Hg. The study will have 80% power to detect a difference of 15% in the glaucoma surgery rate.

TRIAL REGISTRATION: ISRCTN44464607.

Gapped Two-Body Hamiltonian for Continuous-Variable Quantum Computation

We introduce a family of Hamiltonian systems for measurement-based quantum computation with continuous variables. The Hamiltonians (i) are quadratic, and therefore two body, (ii) are of short range, (iii) are frustration-free, and (iv) possess a constant energy gap proportional to the squared inverse of the squeezing. Their ground states are the celebrated Gaussian graph states, which are universal resources for quantum computation in the limit of infinite squeezing. These Hamiltonians constitute the basic ingredient for the adiabatic preparation of graph states and thus open new venues for the physical realization of continuous-variable quantum computing beyond the standard optical approaches. We characterize the correlations in these systems at thermal equilibrium. In particular, we prove that the correlations across any multipartition are contained exactly in its boundary, automatically yielding a correlation area law. © 2011 American Physical Society.

The United Kingdom Glaucoma Treatment Study:a multicenter, randomized, placebo-controlled clinical trial: design and methodology

Elevated intraocular pressure (IOP) is a major risk factor for the deterioration of open-angle glaucoma (OAG); medical IOP reduction is the standard treatment, yet no randomized placebo-controlled study of medical IOP reduction has been undertaken previously. The United Kingdom Glaucoma Treatment Study (UKGTS) tests the hypothesis that treatment with a topical prostaglandin analog, compared with placebo, reduces the frequency of visual field (VF) deterioration events in OAG patients by 50% over a 2-year period.

Relationship between socioeconomic deprivation or urban/rural residence and visual acuity before cataract surgery in Northern Scotland

Purpose: To evaluate the influence of socioeconomic factors on visual acuity before cataract surgery. ?Methods: The medical case notes of 240 consecutive patients listed for cataract surgery from January 1, 2010, at Grampian University Hospital, Aberdeen, were reviewed retrospectively. Patients with ocular comorbidity were excluded. Demographics, postal codes, and visual acuity were recorded. Scottish Index of Multiple Deprivation was used to determine the deprivation rank. Home location was classified as urban or rural. The effect of these parameters on preoperative visual acuity was investigated using chi-square tests or Fisher exact test as appropriate. ?Results: A total of 184 patients (mean 75 years) were included. A total of 127 (69%) patients had visual acuity of 6/12 or better. An association was found between affluence and preoperative visual acuity of 6/12 or better (?2trend = 4.97, p = 0.03), with a significant rising trend across quintile of deprivation. There was no evidence to suggest association between geographical region and preoperative visual acuity (p = 0.63). ?Conclusion: Affluence was associated with good visual acuity (6/12 or better) before cataract surgery. There was no difference in preoperative visual acuity between rural and urban populations.

Intra-operative decision making by ophthalmic surgeons

Research on surgical decision making and risk management usually focuses on peri-operative care, despite the magnitude and frequency of intra-operative risks. The aim of this study was to examine ophthalmic surgeons' intra-operative decisions and risk management strategies in order to explore differences in cognitive processes.

The effect of socioeconomic deprivation on corneal graft survival in the United Kingdom

Objective: To investigate the effect of socioeconomic deprivation on cornea graft survival in the United Kingdom.

Design: Retrospective cohort study.

Participants: All the recipients (n = 13?644) undergoing their first penetrating keratoplasty (PK) registered on the United Kingdom Transplant Registry between April 1999 and March 2011 were included.

Methods: Data of patients' demographic details, indications, graft size, corneal vascularization, surgical complication, rejection episodes, and postoperative medication were collected at the time of surgery and 1, 2, and 5 years postoperatively. Patients with endophthalmitis were excluded from the study. Patients' home postcodes were used to determine the socioeconomic status using a well-validated deprivation index in the United Kingdom: A Classification of Residential Neighborhoods (ACORN). Kaplan–Meier survival and Cox proportional hazards regression were used to evaluate the influence of ACORN categories on 5-year graft survival, and the Bonferroni method was used to adjust for multiple comparisons.

Main Outcome Measures: Patients' socioeconomic deprivation status and corneal graft failure.

Results: A total of 13?644 patients received their first PK during the study periods. A total of 1685 patients (13.36%) were lost to follow-up, leaving 11?821 patients (86.64%) for analysis. A total of 138 of the 11?821 patients (1.17%) developed endophthalmitis. The risk of graft failure within 5 years for the patients classified as hard-pressed was 1.3 times that of the least deprived (hazard ratio, 1.3; 95% confidence interval, 1.1–1.5; P = 0.003) after adjusting for confounding factors and indications. There were no statistically significant differences between the causes of graft failure and the level of deprivation (P = 0.14).

Conclusions: Patients classified as hard-pressed had an increased risk of graft failure within 5 years compared with the least deprived patients.

Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article

A low-cost solution for the restoration of femoral head centre during total hip arthroplasty

Restoration of joint centre during total hip arthroplasty is critical. While computer-aided navigation can improve accuracy during total hip arthroplasty, its expense makes it inaccessible to the majority of surgeons. This article evaluates the use, in the laboratory, of a calliper with a simple computer application to measure changes in femoral head centres during total hip arthroplasty. The computer application was designed using Microsoft Excel and used calliper measurements taken pre- and post-femoral head resection to predict the change in head centre in terms of offset and vertical height between the femoral head and newly inserted prosthesis. Its accuracy was assessed using a coordinate measuring machine to compare changes in preoperative and post-operative head centre when simulating stem insertion on 10 sawbone femurs. A femoral stem with a modular neck was used, which meant nine possible head centre configurations were available for each femur, giving 90 results. The results show that using this technique during a simulated total hip arthroplasty, it was possible to restore femoral head centre to within 6?mm for offset (mean 1.67?±?1.16?mm) and vertical height (mean 2.14?±?1.51?mm). It is intended that this low-cost technique be extended to inform the surgeon of a best-fit solution in terms of neck length and neck type for a specific prosthesis.