Individualised variable-interval risk-based screening for sight-threatening diabetic retinopathy: the Liverpool Risk Calculation Engine.

AIMS/HYPOTHESIS: Individualised variable-interval risk-based screening offers better targeting and improved cost-effectiveness in screening for diabetic retinopathy. We developed a generalisable risk calculation engine (RCE) to assign personalised intervals linked to local population characteristics, and explored differences in assignment compared with current practice. METHODS: Data from 5 years of photographic screening and primary care for people with diabetes, screen negative at the first of > 1 episode, were combined in a purpose-built near-real-time warehouse. Covariates were selected from a dataset created using mixed qualitative/quantitative methods. Markov modelling predicted progression to screen-positive (referable diabetic retinopathy) against the local cohort history. Retinopathy grade informed baseline risk and multiple imputation dealt with missing data. Acceptable intervals (6, 12, 24 months) and risk threshold (2.5%) were established with patients and professional end users. RESULTS: Data were from 11,806 people with diabetes (46,525 episodes, 388 screen-positive). Covariates with sufficient predictive value were: duration of known disease, HbA1c, age, systolic BP and total cholesterol. Corrected AUC (95% CIs) were: 6 months 0.88 (0.83, 0.93), 12 months 0.90 (0.87, 0.93) and 24 months 0.91 (0.87, 0.94). Sensitivities/specificities for a 2.5% risk were: 6 months 0.61, 0.93, 12 months 0.67, 0.90 and 24 months 0.82, 0.81. Implementing individualised RCE-based intervals would reduce the proportion of people becoming screen-positive before the allocated screening date by > 50% and the number of episodes by 30%. CONCLUSIONS/INTERPRETATION: The Liverpool RCE shows sufficient performance for a local introduction into practice before wider implementation, subject to external validation. This approach offers potential enhancements of screening in improved local applicability, targeting and cost-effectiveness.

Predictive value of N95 waveforms of pattern electroretinograms (PERGs) in children with optic nerve hypoplasia (ONH).

PURPOSE: As part of a long-term, prospective study of prenatal and clinical risk factors for optic nerve hypoplasia (ONH) at Children's Hospital Los Angeles, pattern ERGs (PERGs) were evaluated for prognostic value using an automated objective and robust analytical method. METHODS: Participants were 33 children with ophthalmoscopically diagnosed ONH [disc diameter-to-disc macula ratio (DD/DM) less than 0.35 in one or both eyes on fundus photographs]. Using cycloplegia and chloral hydrate sedation in one session before 26 months of age, we recorded PERGs to checkerboard reversal using five check sizes. Participants were followed with clinical and psychometric testing until 5 years of age. PERGs were analysed using automated robust statistics based on magnitude-squared coherence and bootstrapping optimized to objectively quantify PERG recovery in the challenging recordings encountered in young patients. PERG measures in the fixating or better-seeing eyes were compared with visual outcome data. RESULTS: PERG recording was complete to at least three check sizes in all eyes and to all five sizes in 79%. Probability of recording a PERG that is significantly different from noise varied with check size from 73% for the largest checks to 30% for the smallest checks (p = 0.002); smaller waveforms were associated with earlier implicit times. The presence of significant PERGs in infancy is associated with better visual outcomes; the strongest association with visual outcome was for the threshold check size with a significant N95 component (ρ = 0.398, p = 0.02). CONCLUSIONS: Automated statistically robust signal-processing techniques reliably and objectively detect PERGs in young children with ONH and show that congenital deficits of retinal ganglion cells are associated with diminished or non-detectable PERGs. The later negativity, N95, was the best indicator of visual prognosis and was most useful to identify those with good visual outcomes (≤0.4 LogMAR). Although PERGs reflect function of the inner layers of the central retina, they lack the specificity required to determine prognosis reliably in individual cases.

Temporary sympathectomy in chronic refractory angina: a randomised, double-blind, placebo-controlled trial.

BACKGROUND: Temporary sympathectomy by injection of bupivacaine at the site of the left stellate ganglion is used in the management of refractory angina at several UK centres. Although patients frequently report significant reduction in symptoms, efficacy has not been established by double-blind, randomised placebo-controlled trial (RCT). OBJECTIVE: To investigate the efficacy of the procedure for the first time by a double-blind RCT. METHODS: Consecutive patients referred to the authors' National Health Service (NHS) angina centre who were candidates for temporary sympathectomy were invited to participate in a trial. A total of 65 patients were randomised to receive either bupivacaine or saline injections. Identical syringes were prepared remotely, blinding patients and staff from randomisation. Cardiac autonomic function was measured 3 hours pre- and post-injection using new heart rate variability (HRV) analyses. Angina episodes were recorded contemporaneously by patients in study diaries in the 7-day periods pre- and post-injection. RESULTS: In 51 patients suitable for analysis, no significant differences between the active and placebo groups were found in patient-recorded frequency or intensity of angina episodes pre- and post-injection. However, across both groups combined, a significant difference was found in the frequency of angina episodes pre- and post-injection. CONCLUSION: The reduction in frequency of angina episodes produced by this procedure may not be due to drug pharmacology. It may be a placebo response or due to the mechanical effects of the injection of fluid. There is a need for further work using a larger patient cohort considering both mechanical and psychological factors.

Comparison of human expert and computer-automated systems using magnitude-squared coherence (MSC) and bootstrap distribution statistics for the interpretation of pattern electroretinograms (PERGs) in infants with optic nerve hypoplasia (ONH).

PURPOSE: Pattern electroretinograms (PERGs) have inherently low signal-to-noise ratios and can be difficult to detect when degraded by pathology or noise. We compare an objective system for automated PERG analysis with expert human interpretation in children with optic nerve hypoplasia (ONH) with PERGs ranging from clear to undetectable. METHODS: PERGs were recorded uniocularly with chloral hydrate sedation in children with ONH (aged 3.5-35 months). Stimuli were reversing checks of four sizes focused using an optical system incorporating the cycloplegic refraction. Forty PERG records were analysed; 20 selected at random and 20 from eyes with good vision (fellow eyes or eyes with mild ONH) from over 300 records. Two experts identified P50 and N95 of the PERGs after manually deleting trials with movement artefact, slow-wave EEG (4-8 Hz) or other noise from raw data for 150 check reversals. The automated system first identified present/not-present responses using a magnitude-squared coherence criterion and then, for responses confirmed as present, estimated the P50 and N95 cardinal positions as the turning points in local third-order polynomials fitted in the -3 dB bandwidth [0.25 … 45] Hz. Confidence limits were estimated from bootstrap re-sampling with replacement. The automated system uses an interactive Internet-available webpage tool (see http://clinengnhs.liv.ac.uk/esp_perg_1.htm). RESULTS: The automated system detected 28 PERG signals above the noise level (p ≤ 0.05 for H0). Good subjective quality ratings were indicative of significant PERGs; however, poor subjective quality did not necessarily predict non-significant signals. P50 and N95 implicit times showed good agreement between the two experts and between experts and the automated system. For the N95 amplitude measured to P50, the experts differed by an average of 13% consistent with differing interpretations of peaks within noise, while the automated amplitude measure was highly correlated with the expert measures but was proportionally larger. Trial-by-trial review of these data required approximately 6.5 h for each human expert, while automated data processing required <4 min, excluding overheads relating to data transfer. CONCLUSIONS: An automated computer system for PERG analysis, using a panel of signal processing and statistical techniques, provides objective present/not-present detection and cursor positioning with explicit confidence intervals. The system achieves, within an efficient and robust statistical framework, estimates of P50 and N95 amplitudes and implicit times similar to those of clinical experts.

Cluster analysis of multiplex ligation-dependent probe amplification data in choroidal melanoma.

PURPOSE: To determine underlying correlations in multiplex ligation-dependent probe amplification (MLPA) data and their significance regarding survival following treatment of choroidal melanoma (CM). METHODS: MLPA data were available for 31 loci across four chromosomes (1p, 3, 6, and 8) in tumor material obtained from 602 patients with CM treated at the Liverpool Ocular Oncology Center (LOOC) between 1993 and 2012. Data representing chromosomes 3 and 8q were analyzed in depth since their association with CM patient survival is well-known. Unsupervised k-means cluster analysis was performed to detect latent structure in the data set. Principal component analysis (PCA) was also performed to determine the intrinsic dimensionality of the data. Survival analyses of the identified clusters were performed using Kaplan-Meier (KM) and log-rank statistical tests. Correlation with largest basal tumor diameter (LTD) was investigated. RESULTS: Chromosome 3: A two-cluster (bimodal) solution was found in chromosome 3, characterized by centroids at unilaterally normal probe values and unilateral deletion. There was a large, significant difference in the survival characteristics of the two clusters (log-rank, p<0.001; 5-year survival: 80% versus 40%). Both clusters had a broad distribution in LTD, although larger tumors were characteristically in the poorer outcome group (Mann-Whitney, p<0.001). Threshold values of 0.85 for deletion and 1.15 for gain optimized the classification of the clusters. PCA showed that the first principal component (PC1) contained more than 80% of the data set variance and all of the bimodality, with uniform coefficients (0.28±0.03). Chromosome 8q: No clusters were found in chromosome 8q. Using a conventional threshold-based definition of 8q gain, and in conjunction with the chromosome 3 clusters, three prognostic groups were identified: chromosomes 3 and 8q both normal, either chromosome 3 or 8q abnormal, and both chromosomes 3 and 8q abnormal. KM analysis showed 5-year survival figures of approximately 97%, 80%, and 30% for these prognostic groups, respectively (log-rank, p<0.001). All MLPA probes within both chromosomes were significantly correlated with each other (Spearman, p<0.001). CONCLUSIONS: Within chromosome 3, the strong correlation between the MLPA variables and the uniform coefficients from the PCA indicates a lack of evidence for a signature gene that might account for the bimodality we observed. We hypothesize that the two clusters we found correspond to binary underlying states of complete monosomy or disomy 3 and that these states are sampled by the complete ensemble of probes. Consequently, we would expect a similar pattern to emerge in higher-resolution MLPA data sets. LTD may be a significant confounding factor. Considering chromosome 8q, we found that chromosome 3 cluster membership and 8q gain as traditionally defined have an indistinguishable impact on patient outcome.

Shoulder muscle activation and coordination in patients with a massive rotator cuff tear: an electromyographic study.

Adaptive muscle activation strategies following a massive rotator cuff tear (MRCT) are inadequately understood, and the relationship among muscles during everyday activities has not been considered. Thirteen healthy subjects comprised the control group, and 11 subjects with a MRCT the patient group. Upper limb function was assessed using the Functional Impairment test-hand, neck, shoulder, and arm (FIT-HaNSA). Electromyography (EMG) was recorded from 13 shoulder muscles, comprising five muscle groups, during a shelf-lifting task. Mean FIT-HaNSA scores were significantly lower in MRCT patients (p≤0.001), reflecting a severe functional deficit. In MRCT patients, EMG signal amplitude was significantly higher for the biceps brachii-brachioradialis (p < 0.001), upper trapezius-serratus anterior (p= 0.025), muscle groups and for the latissimus dorsi (p = 0.010), and teres major (p=0.007) muscles. No significant differences in the correlation among muscle groups were identified, pointing to an unchanged neuromuscular strategy following a tear. In MRCT patients, a reorganization of muscle activation strategy along the upper limb kinetic chain is aimed at reducing demand on the glenohumeral joint. Increased activation of the latissimus dorsi and teres major muscles is an attempt to compensate for the deficient rotator cuff. Re-education towards an alternate neuromuscular control strategy appears necessary to restore function.

Normal shoulder muscular activation and co-ordination during a shoulder elevation task based on activities of daily living: an electromyographic study.

Studies of normal shoulder function have often failed to consider the inter-relationship between different muscle groups in activities relevant to daily life. Upper limb functional status was assessed in 12 healthy male volunteers using the Functional Impairment Test-Hand, Neck, Shoulder and Arm test (FIT-HaNSA). Electromyography was then used to study the activity and coordination of 13 muscles (10 by surface electrodes, 3 by fine-wire intramuscular electrodes) around the shoulder during a dynamic movement task based on the shelf-lifting task in FIT-HaNSA. Muscles were grouped for analysis into deltoid (anterior, middle, and posterior divisions), adductors (latissimus dorsi and teres major), rotator cuff (supraspinatus, infraspinatus, and subscapularis), and elbow flexor (brachioradialis, biceps brachii) groups. There were no significant inter-session effects. Using cross-correlation analysis to investigate the whole time-course of activation, there were highly significant positive correlations (p < 0.001) between the deltoid and rotator cuff, the deltoid and adductor and the adductor and rotator cuff groups, and a significant negative correlation between the deltoid and elbow flexor groups (p = 0.031). We conclude that the deltoid, adductor, and rotator cuff muscles all contribute to the muscular component of glenohumeral joint stability. Muscular stability can be adapted as required to meet task-specific demands.

Investigation of the temporal properties of the retina using the m-sequence.

The mfERG provides a topographic map of function of the retina and has been used in numerous studies to identify macular, paramacular and peripheral retinal dysfunction. This study investigates the changes in response due to the presentation rate of the stimulus. Twenty subjects gave informed consent to take part in the study, which had local regional ethical committee approval. Only a single hexagon of 8° diameter was presented to reduce ambiguity when identifying the higher-order kernels (HOK). Six rates were tested using a 60-Hz CRT monitor by introducing blank (black ~0 cd/m2) filler frames (FF). The rates tested were 0FF; 1FF; 2FF; 4FF; 7FF; and 14FF. The first-order kernel had largest responses to the slower stimuli (4FF and above). HOK had largest amplitudes at faster rates with the second-order kernel peaking at 1FF. At rates with 4FF and slower, the higher-order kernels were indiscernible above the noise.

Changing characteristics and mode of death associated with chronic heart failure caused by left ventricular systolic dysfunction: a study across therapeutic eras.

BACKGROUND: Therapies for patients with chronic heart failure caused by left ventricular systolic dysfunction have advanced substantially over recent decades. The cumulative effect of these therapies on mortality, mode of death, symptoms, and clinical characteristics has yet to be defined. METHODS AND RESULTS: This study was a comparison of 2 prospective cohort studies of outpatients with chronic heart failure caused by left ventricular systolic dysfunction performed between 1993 and 1995 (historic cohort: n=281) and 2006 and 2009 (contemporary cohort: n=357). In the historic cohort, 83% were prescribed angiotensin-converting enzyme inhibitors and 8.5% were prescribed ß-adrenoceptor antagonists, compared with 89% and 80%, respectively, in the contemporary cohort. Mortality rates over the first year of follow-up declined from 12.5% to 7.8% between eras (P=0.04), and sudden death contributed less to contemporary mortality (33.6% versus 12.7%; P<0.001). New York Heart Association class declined between eras (P<0.001). QTc dispersion across the chest leads declined from 85 ms (SD, 2) to 34 ms (SD, 1) and left ventricular end-diastolic dimensions declined from 65 mm (SD, 0.6) to 59 mm (SD, 0.5) (both P<0.001). CONCLUSIONS: Survival has significantly improved in patients with chronic heart failure caused by left ventricular systolic dysfunction over the past 15 years; furthermore, sudden death makes a much smaller contribution to mortality, and noncardiac mortality is a correspondingly greater contribution. This has been accompanied by an improvement in symptoms and some markers of adverse electric and structural left ventricular remodeling.

A clinical alternative to fluorophotometry for measuring tear production in the diagnosis of dry eye.

PURPOSE: To determine the utility of the tear function index (Liverpool modification TFI) in assessing tear turnover rate (TTR), evaluate association of tear clearance rate (TCR) and TFI with measurements of TTR by fluorophotometry, and determine effectivity of these test measures in dry eye (DE) diagnosis. METHODS: Forty-one subjects with DE and 15 control subjects participated. Tests included symptoms, fluorophotometry (by automated scanning fluorophotometry), and TCR and TFI from a prepared Liverpool modification TFI strip. RESULTS: Significant differences between subjects with DE and control subjects were found for all tests. Although wetting length values gave highest sensitivity (SS) and specificity (SP) (71% and 73%, respectively), this resulted from a high degree of selection bias because the Schirmer test was one of the inclusion criteria for patients entering the study. Therefore, the best tear production test was found to be TTR (SS 71% and SP 60%). The TTR test is not readily available in clinical settings; therefore, associations between the TTR test and other tests were determined. Significant correlations were found between TTR and wetting length/TCR/TFI, indicating these latter clinical tests useful as surrogates. The strongest correlations, TTR/TCR at 0.69 (P = 0.000) and TTR/TFI at 0.65 (P = 0.000), indicate TCR/TFI with the Liverpool test can be used as an alternative to TTR by fluorophotometry. The diagnostic effectiveness between these tests was compared, with both TCR and TFI found to have equal effectivity of 78% SS and 40% SP (TCR) and 83% SS and 40% SP (TFI). CONCLUSIONS: TCR measured by the commercially available Liverpool modification TFI strip is an acceptable alternative to TTR by fluorophotometry as a measure of tear production. It is effective as a single test for the discrimination of those with DE from those without the condition.

Pattern recognition of vertical strabismus using an artificial neural network (StrabNet).

BACKGROUND: Our goal is to develop an accessible expert system (StrabNet) that will assist in the clinical diagnosis of vertical strabismus, form the basis of a teaching/learning tool, and contribute to the audit process. Potentially, this model can be extended to other strabismus deviations. METHODS: Vertical deviations were separated into eight classifications (diagnoses). An expert system based on architecture of artificial neural networks learned the patterns for each class of deviation based on 10 prism cover-test measurements (9 cardinal positions and near fixation). The expert system was tested with previously unseen and real-patient data. This system was extended to a reduced model requiring only six measurements (primary position, right, left, up, down gaze, and near fixation), and evaluated with real patient data. A freely available Web implementation is available on the Internet at www.StrabNet.com . RESULTS: The expert system was found to be highly accurate at diagnosing vertical strabismus (100% and approximately 96% for ten and six measurement models, respectively) from one of the eight classes. CONCLUSION: StrabNet is of demonstrable value in diagnosing commonly presenting vertical deviations from prism cover test (PCT) measurements. Its potential role in teaching and in audit is identified.

Assessment of functional recovery in tennis elbow.

OBJECTIVES: (a) To investigate changes in muscular strength, fatigue and activity in recovered tennis elbow (RTE); (b) to assess the appropriateness of EMG and strength measurements in monitoring functional recovery in tennis elbow (TE). METHODS: Study included three age-matched female groups of Control (C) (n=8, no history of musculoskeletal problems), TE (n=7, local tenderness at the lateral epicondyle and pain with resisted wrist and middle finger extension) and RTE (n=6, asymptomatic for at least 6 months, no lateral epicondyle tenderness). Measurements included metacarpophalangeal (MCP), wrist, shoulder and grip isometric strength and EMG measures of muscle fatigue and activity for five forearm muscles (wrist extensors and flexors). RESULTS: Strength was greater (p<0.05) for all measurements in C compared to RTE and TE except for MCP extension. Only MCP extension was stronger in RTE than TE. EMG revealed increased activity of extensor carpi radialis (ECR) in RTE, decreased in TE. CONCLUSIONS: Despite attenuation of pain, global upper limb weakness in RTE indicated incomplete functional recovery. Increased strength of MCP extension may protect weakened wrist extensors from further injury. Monitoring the ECR activity as well as strength measurements may provide a useful assessment of functional recovery in TE.

The behaviour of knots and sutures during the first 12 hours following a Bankart repair.

It has been reported that the effectiveness of arthroscopic procedures in terms of preventing recurrent dislocation has not matched that from open techniques. Also little is known about how these knots behave when exposed to physiological loading following repair. This study presents the development of a practical tool to allow surgeons to test the quality of their arthroscopic knots and allow them to make choices with regard to knot configuration and suture material. This study uses an apparatus to model the repair of a Bankart lesion. Ten examples of the Duncan loop and SMC knots were tied using PDS, Ethibond, Panacryl and Fibrewire. An arthroscopic knotting technique was used. Reverse slippage occurring during the tying process was recorded. Each knot was then left for 12 hours under loads equivalent to a Bankart repair and the subsequent reverse slippage was recorded. After initial passing of the Duncan loop and after passing of locking hitches the sutures were ranked inversely to size of suture loop (resistance to slippage). Only Fibrewire showed a significant difference (5.7 +/- 1.03 mm to 5.66 +/- 0.5 mm; p <0.05). After 12 hrs, some evidence of reverse slippage was noted, especially with Fibrewire (5.66 +/- 0.5 mm--significant p <0.05). The SMC knot showed generally inferior results. In this study using arthroscopic techniques, Fibrewire performed less well than other materials.

A web-based tool for the assessment of discrimination and calibration properties of prognostic models.

Prognostic models are developed to assist clinicians in making decisions regarding treatment and follow-up management. The accuracy of these models is often assessed either in terms of their discrimination performance or calibration but rarely both. In this paper, we describe the development of an online tool for discrimination using Harrell C index and calibration using a Hosmer-Lemeshow type analysis (http://clinengnhs.liv.ac.uk/AADP/AADP_Welcome.htm). We show examples of using the tool on real data. We highlight situations where the model performed well in terms of either discrimination or calibration but not both depending on the sample size of the test set. We conclude that prognostic models should be assessed both in terms of discrimination and calibration and that calibration analysis should be carried out numerically and graphically.

Artificial neural networks estimating survival probability after treatment of choroidal melanoma.

PURPOSE: To describe neural networks predicting survival from choroidal melanoma (i.e., any uveal melanoma involving choroid) and to demonstrate the value of entering age, sex, clinical stage, cytogenetic type, and histologic grade into the predictive model. DESIGN: Nonrandomized case series. PARTICIPANTS: Patients resident in mainland Britain treated by the first author for choroidal melanoma between 1984 and 2006. METHODS: A conditional hazard estimating neural network (CHENN) was trained according to the Bayesian formalism with a training set of 1780 patients and evaluated with a test set of another 874 patients. Conditional hazard estimating neural network-generated survival curves were compared with those obtained with Kaplan-Meier analyses. A second model was created with information on chromosome 3 loss, using training and test sets of 211 and 140 patients, respectively. MAIN OUTCOME MEASURES: Comparison of CHENN survival curves with Kaplan-Meier analyses. Representative results showing all-cause survival and inferred melanoma-specific mortality, according to age, sex, clinical stage, cytogenetic type, and histologic grade. RESULTS: The predictive model plotted a survival curve with 95% credibility intervals for patients with melanoma according to relevant risk factors: age, sex, largest basal tumor diameter, ciliary body involvement, extraocular extension, tumor cell type, closed loops, mitotic rate, and chromosome 3 loss (i.e., monosomy 3). A survival curve for the age-matched general population of the same sex allowed estimation of the melanoma-related mortality. All-cause survival curves generated by the CHENN matched those produced with Kaplan-Meier analysis (Kolmogorov-Smirnov, P<0.05). In older patients, however, the estimated melanoma-related mortality was lower with the CHENN, which accounted for competing risks, unlike Kaplan-Meier analysis. Largest basal tumor diameter was most predictive of mortality in tumors showing histologic and cytogenetic features of high-grade malignancy. Ciliary body involvement and extraocular extension lost significance when cytogenetic and histologic data were included in the model. Patients with a monosomy 3 melanoma of a particular size were predicted to have shorter survival if their tumor showed epithelioid cells and closed loops. CONCLUSIONS: Estimation of survival prognosis in patients with choroidal melanoma requires multivariate assessment of age, sex, clinical tumor stage, cytogenetic melanoma type, and histologic grade of malignancy.

Heat treatment of arthroscopic knots and its effect on knot security.

PURPOSE: The purpose of this study was to investigate heat application to arthroscopic knots as a method of improving knot security. METHODS: Heat treatment was assessed on 4 suture materials--Ethibond (Ethicon, Somerville, NJ), PDS (Ethicon), Orthocord (DePuy Mitek, Raynham, MA), and FiberWire (Arthrex, Naples, FL)--tied by use of the Duncan loop, compared with untreated controls. A hand-tied surgeon's knot with Ethibond was included as the gold standard. Knots were tied around a plastic rod immersed in a saline solution-filled water bath at 37 degrees C, with heat treatment performed by use of the Mitek VAPR 3 electrosurgical unit and VAPR S(90) electrode (DePuy Mitek), applied directly to the knot body. Loops were subjected to a 5-N preload, followed by loading to clinical failure (>3 mm of displacement) and ultimate (breaking) failure by use of a tensile tester. RESULTS: Load to ultimate failure was significantly higher in the FiberWire 1-second heat treatment arm (26.0% increase, 234.25 +/- 62.34 N, P < .03), Orthocord 1-second heat treatment arm (55.6% increase, 204.72 +/- 78.47 N, P < .03), and Orthocord 5-second heat treatment arm (69.2% increase, 222.58 +/- 56.57 N, P < .001) than in controls. Load to clinical failure was significantly higher in the Orthocord 10-second heat treatment arm (34.7% increase, 78.58 +/- 13.88 N, P < .0001) when compared with controls. The FiberWire 5- and 10-second heat treatment arms showed lower load to clinical and ultimate failure (P < .001). Ethibond, Orthocord, and FiberWire showed higher load to clinical failure than PDS (P < .0001). Ethibond and Orthocord knots were more likely to fail through knot slippage after heat treatment compared with controls (P < .01). CONCLUSIONS: Heat treatment resulted in greater knot security when combined with Orthocord and FiberWire suture materials. Heat-treated Ethibond and Orthocord knots were more likely to fail through suture breakage than knot slippage. CLINICAL RELEVANCE: This study presents a simple and novel technique of improving knot security in the arthroscopic repair. The effects of heat were extremely well tolerated in the Orthocord and FiberWire groups, making this technique particularly suitable for clinical use.

Deficits in the electroretinogram in neovascular age-related macular degeneration and changes during photodynamic therapy.

PURPOSE: To describe the deficits in four electroretinography (ERG) modalities in patients with neovascular age-related macular degeneration (AMD). To describe the changes in these parameters during a course of verteporfin photodynamic therapy (PDT). METHODS: Pattern (PERG), multifocal (mfERG) (19 segment simplified test protocol), flash ERG and flicker ERG were performed in patients with active neovascular AMD before PDT and compared to fellow eye controls using paired t-tests. Changes in ERG parameters during the 12 month treatment course were visualised using 95% confidence intervals of the median difference. The statistical significance of any changes was quantified using Wilcoxon signed ranks tests. RESULTS: Fifty patients were recruited and followed. At presentation all ERG amplitudes were reduced with greater reductions in focal as opposed to global test protocols (P < 0.05). Over the 12 month course of PDT, PERG P50 amplitude showed a general downward trend and latency remained unchanged. mfERG p1 amplitude density showed an upward trend at six months before returning to baseline by 12 months. mfERG ring 2 amplitude density was significantly increased at 12 months compared to baseline (P = 0.010). Flicker ERG latency was significantly increased at six months compared to baseline (P = 0.015). DISCUSSION: The simplified mfERG protocol was tolerated by this patient group, however, they found the full test protocol demanding. Large deficits in the retinal ERG function occur in neovascular AMD and involve retinal locations adjacent to as well as overlying choroidal neovascularisation (CNV). After PDT there is an improvement in electro-retinal function in retinal locations overlying the CNV.

The differential diagnosis of vertical strabismus from prism cover test data using an artificially intelligent expert system.

An expert system is described for the differential diagnosis of vertical deviation strabismus (squint) from measurements taken in the standard prism cover test. The deviations are represented as optical powers in prism dioptres using the graphic representation of strabismus (after Jampolsky). The expert is implemented in MatLab (Mathworks Ltd., Cambridge, UK) both as a stand-alone program on a PC and as a web application available over the Internet (see http://www.strabnet.com ). In trial and clinical datasets a diagnostic accuracy of 100% was achieved.

Upper limb muscle imbalance in tennis elbow: a functional and electromyographic assessment.

The purpose of this study was to investigate strength, fatigability, and activity of upper limb musculature to elucidate the role of muscular imbalance in the pathophysiology of tennis elbow. Sixteen patients clinically diagnosed with tennis elbow, recruited from a university hospital upper limb orthopedic clinic, were compared with 16 control subjects with no history of upper limb musculoskeletal problem, recruited from university students and staff. Muscle strength was measured for grip, metacarpophalangeal, wrist, and shoulder on both sides. Electromyographic activity (RMS amplitude) and fatigue characteristics (median frequency slope) of five forearm and two shoulder muscles were measured during isometric contraction at 50% maximum voluntary contraction. All strength measurements showed dominance difference in C, but none in TE. In tennis elbow compared to controls, hand/wrist and shoulder strength and extensor carpi radialis (ECR) activity were reduced (p < 0.05), while fatigue was normal. A global upper limb weakness exists in tennis elbow. This may be due to disuse and deconditioning syndrome caused by fear avoidance, and needs to be addressed in prevention and treatment. Activation imbalance among forearm muscles (reduced extensor carpi radialis activity) in tennis elbow, probably due to protective pain-related inhibition, could lead to a widespread upper limb muscle imbalance.

Pain, functional disability, and psychologic status in tennis elbow.

OBJECTIVES: First to compare pain and functional disability in tennis elbow (TE) patients with healthy controls. Second, to evaluate the relationship between the 2 major psychologic factors (anxiety and depression) and TE. METHODS: Sixteen TE patients were recruited from 46 consecutive attendees at an upper limb clinic: inclusion criteria were lateral epicondyle tenderness, pain with resisted wrist and middle finger extension and at least 3 months localized lateral elbow pain. Sixteen healthy controls with no upper limb problem were recruited from students and staff. Participants were given 4 questionnaires, together with instructions for completion: Disabilities of the Arm, Shoulder, and Hand, Patient-Rated Forearm Evaluation Questionnaire, Patient-Rated Wrist Evaluation Questionnaire, and Hospital Anxiety and Depression Scale. The independent t test was used to compare the total and subscale scores between the groups. RESULTS: Significantly higher scores were found in TE for pain and function subscales and also total score for Disabilities of the Arm, Shoulder, and Hand, Patient-Rated Forearm Evaluation Questionnaire, and Patient-Rated Wrist Evaluation Questionnaire. For Hospital Anxiety and Depression Scale, both anxiety and depression subscales (P<0.001) and the total score (P<0.01) were significantly higher in TE. According to the anxiety and depression subscales, 55% and 36% of patients, respectively, were classified as probable cases (score >11). DISCUSSION: TE patients showed markedly increased pain and functional disability. Significantly elevated levels of depression and anxiety pointed out the importance of psychologic assessment in TE patients. In the development of supportive and treatment strategies, we suggest the combination of "upper limb" and "psychologic" assessment tools.