Development and validation of a Bayesian network for the differential diagnosis of anterior uveitis.

PurposeTo develop and validate a Bayesian belief network algorithm for the differential diagnosis of anterior uveitis.Patients and methodsThe 11 most common etiologies were included (idiopathic, ankylosing spondylitis, psoriasic arthritis, reactive arthritis, inflammatory bowel diseases, sarcoidosis, tuberculosis, Behçet, Posner-Schlossman syndrome, juvenile idiopathic arthritis (JIA), and Fuchs' heterochromic cyclitis). Frequencies of association between factors and etiologies were retrieved from a systematic review of the literature. Prevalences were calculated using a random sample of 200 patients receiving a diagnosis of anterior uveitis in Moorfields Eye Hospital in 2012. The network was validated in a random sample of 200 patients receiving a diagnosis of anterior uveitis in the same hospital in 2013 plus 10 extra cases of the most rare etiologies (JIA, Behçet, and psoriasic arthritis).ResultsIn 63.8% of patients the most probable etiology by the algorithm matched the senior clinician diagnosis. In 80.5% of patients the clinician diagnosis matched the first or second most probable results by the algorithm. Taking into account only the most probable diagnosis by the algorithm, sensitivities for each etiology ranged from 100% (7 of 7 patients with reactive arthritis and 5 of 5 with Behçet correctly classified) to 46.7% (7 of 15 patients with tuberculosis-related uveitis). Specificities ranged from 88.8% for sarcoidosis to 99.5% in Posner.ConclusionsThis algorithm could help clinicians with the differential diagnosis of anterior uveitis. In addition, it could help with the selection of the diagnostic tests performed.

The symptom checklist-90-revised and mild traumatic brain injury.

OBJECTIVE: Assessment of emotional functioning is a critical aspect of the clinical neuropsychological evaluation of individuals following mild traumatic brain injury (MTBI). The objective of this study was to examine the utility of the Symptom Checklist-90-Revised as a brief tool for assessing psychological and symptomatic distress following MTBI. METHOD: A contrasted groups approach, involving three clinical groups (MTBI, Whiplash Associated Disorder, Type I Diabetes) and a non-clinical control group, was used in this study. RESULTS: The group with MTBI scored significantly higher on the majority of primary symptom dimensions and global distress indices of the SCL-90-R compared to both the diabetes and non-clinical control groups. Analysis of individual cases further revealed that 68.2% of the participants in the group with MTBI were classified as positive cases, a rate significantly higher than that of the diabetes and non-clinical control groups. The group with MTBI did not differ significantly from the group of individuals with whiplash associated disorder with respect to elevation of primary symptom dimensions or global distress indices, or the number of cases classified as positive. CONCLUSION: The results of this study suggest that the SCL-90-R has considerable utility as a general measure of psychological and symptomatic distress following MTBI.

Interobserver agreement on visual field progression in glaucoma: a comparison of methods.

AIM: To examine the level of agreement between clinicians in assessing progressive deterioration in visual field series using two different methods of analysis. METHODS: Each visual field series satisfied the following criteria: more than 19 reliable fields, patient age over 40 years, macular threshold at least 30 dB. The first three fields in each series were excluded to minimise learning effects: the following 16 were studied. Five expert clinicians assessed the progression status of each series using both standard Humphrey printouts and pointwise linear regression (PROGRESSOR). The level of agreement between the clinicians was evaluated using a weighted kappa statistic. RESULTS: A total of 432 tests comprising 27 visual field series of 16 tests each were assessed by the clinicians. The level of agreement on progression status between the clinicians was always higher when they used PROGRESSOR (median kappa = 0.59) than when they used Humphrey printouts (median kappa = 0.32). This was statistically significant (p = 0.006, Wilcoxon matched pairs signed rank sum test). CONCLUSIONS: Agreement between expert clinicians about visual field progression status is poor when standard Humphrey printouts are used, even when the field series studied are long and consist solely of reliable fields. Under these ideal conditions, clinicians agree more closely about patients' visual field progression status when using PROGRESSOR than when inspecting series of Humphrey printouts.

Use of high spatial resolution perimetry to identify scotomata not apparent with conventional perimetry in the nasal field of glaucomatous subjects.

AIM: To examine whether high spatial resolution perimetry (HSRP) could identify fine scale scotomata which may not be apparent with conventional perimetry. The HSRP was performed in the nasal field, as this location is a recognised site for the early occurrence of glaucomatous defects. METHOD: 16 early glaucoma eyes, 17 glaucoma suspect eyes, and 20 age matched healthy control eyes underwent conventional automated perimetry using the 24-2 program of the Humphrey field analyser (HFA) and HSRP. The HSRP was performed in the nasal field by testing 9 x 9 degrees of 100 tested points separated by 1 degree and the results compared with the HFA 24-2 program. RESULTS: Mean HSRP thresholds were significantly abnormal in the suspect and glaucoma eyes, with elevated levels of asymmetry between the superior and inferior nasal field. Overall, 7/17 (41%) suspect eyes (95% confidence interval 5/17 (29%) to 7/17 (41%)) had nasal scotomata on HSRP, although their HFA 24-2 fields failed to identify any defects. In glaucomatous eyes, 15/16 (94%) eyes had HSRP scotomata (95% CI 14/16 (88%) to 15/16 (94%)). In 12 these coexisted with HFA 24-2 defects at the same location, while in three eyes only HSRP identified scotomata in the nasal field. CONCLUSION: HSRP can identify scotoma in glaucomatous eyes in the nasal field which may be missed with the lower spatial resolution of conventional perimetry.

Failure of accommodation in patients with HIV infection.

PURPOSE: The principal objective was to test the hypothesis that HIV-positive patients have significantly reduced amplitudes of accommodation compared with controls. The secondary objective was to investigate accommodative impairment in relation to factors such as age of susceptibility, CD4 count, viral load and current antiretroviral therapies. METHOD: The study was a single-center open prospective study involving a subject population of 43 HIV-positive men aged from 26 to 39 years with no previous history of eye problems and 21 age-matched healthy male controls. The main outcome measure was the amplitude of accommodation, as measured monocularly with a standard push-up technique. RESULTS: Amplitudes of accommodation were significantly smaller in the HIV-positive group compared with controls for age groups 25-29 (p = 0.016) and 30-34 years (p = 0.030) but not in the older group. In total, 30% (8/27) of patients aged between 25 and 34 years had reduced amplitudes of accommodation below age-expected norms. Accommodative failure was not related to current or lowest CD4 count, viral load or specific antiretroviral therapies. CONCLUSION: This study has identified accommodative failure in a significant proportion of HIV-positive patients aged between 26 and 35 years. This problem may be under-recognised, and further studies are warranted to investigate possible causes.

Effect of age on visual outcome following cataract extraction.

AIM: To determine the effect of age on final corrected visual acuity following cataract extraction. METHODS: A case series of 880 patients aged 60 years and older undergoing cataract extraction between 1996 and 1999 was studied. The best corrected visual acuity was assessed at discharge from the service and the proportion of patients who achieved a postoperative acuity of > or = 6/12 was determined for different age groups. Analysis was also performed after exclusion of patients identified preoperatively as having ocular comorbidity that was thought to limit their final corrected acuity. The odds ratios for visual outcome were calculated for age using multiple logistic regression analysis to adjust for other prognostic factors. RESULTS: A significant age effect was observed, with the proportion of patients who had no ocular comorbidity identified preoperatively and who achieved a visual acuity of > or = 6/12 at discharge decreasing with age (p<0.001). In patients with no comorbidity the odds of achieving an acuity of > or = 6/12 were 4.6 times higher in the 60-69 year age group than in the oldest age group (80+ years). CONCLUSIONS: Age is a significant determinant of visual outcome. This has implications if a points system incorporating an assessment of visual acuity or if visual acuity alone is used to determine the threshold for eligibility for cataract surgery.

Response time prolongation for a motion stimulus in patients with glaucoma and its relationship with elevation of the motion threshold.

PURPOSE: To investigate whether response times for a motion stimulus are prolonged in glaucoma and to investigate the relationship between response time prolongation and motion threshold elevation in glaucoma. METHOD: Motion displacement thresholds and response times were measured in 15 patients with glaucoma and 18 age-matched control subjects. RESULTS: Mean test response times were significantly prolonged in the glaucomatous eyes than in the control eyes, with a mean delay of 200 milliseconds. After correcting for threshold elevation, response times at the motion threshold showed no significant difference between the groups. CONCLUSIONS: Response times for motion detection are significantly prolonged in glaucoma and are accounted for by the threshold elevation in patients with glaucoma. The implications of these results are discussed in terms of the use of response time analysis to determine subject reliability.

Characteristics of frequency-of-seeing curves for a motion stimulus in glaucoma eyes, glaucoma suspect eyes, and normal eyes.

This study compared frequency-of-seeing curves for a line displacement test in glaucoma patients and normals. Probit analysis of the frequency-of-seeing curves provided the motion thresholds and the slopes of the frequency-of-seeing curves, represented by the interquartile range. The thresholds and interquartile ranges were significantly elevated in the glaucoma eyes and suspect eyes, compared to controls. A logistic regression model incorporating both the interquartile range and threshold significantly improved the sensitivity of the motion test in the suspects. Abnormal shallowing of the slope of the motion frequency-of-seeing curve may represent one of the earliest changes in glaucoma.

Abnormal motion displacement thresholds are associated with fine scale luminance sensitivity loss in glaucoma.

This study tests the hypothesis that abnormal motion displacement thresholds coexist with scotomas on a finer spatial scale than is measurable by conventional Humphrey perimetry. Eighteen patients with primary open angle glaucoma in one eye, and 18 age matched normal controls underwent motion displacement threshold testing and high spatial resolution perimetry. The motion displacement thresholds were significantly elevated in the glaucoma eyes, in 73% this exceeded normal limits. Ten glaucoma eyes had normal Humphrey 24-2 field nearest the motion test site: of these seven had abnormally elevated motion displacement thresholds and six had fine scale threshold depressions detected with high spatial resolution perimetry. This result suggests that glaucomatous elevations of motion displacement threshold may be present in areas of normal Humphrey 24-2 field, and this may coexist with measurable scotomas beyond the resolution of conventional Humphrey perimetry in some, but not all patients.

High spatial resolution automated perimetry in glaucoma.

BACKGROUND: Automated perimetry is of fundamental importance in assessing visual function in glaucoma. A technique was evaluated to perform high spatial resolution automated perimetry to allow a more detailed assessment of the luminance sensitivity in selected regions of the visual field than is possible with conventional perimetry. METHOD: High spatial resolution perimetry was performed using a Humphrey automated perimeter by measuring luminance sensitivity across a 9 by 9 degree custom grid of 100 test locations with a separation between adjacent locations of 1 degree. Quantitative analysis of the raw and Gaussian filtered thresholds was performed to assess the repeatability of the technique in normals, glaucoma suspects, and glaucoma patients. RESULTS: The testing protocol was well tolerated by all subjects. High spatial resolution perimetry in glaucomatous eyes demonstrated fine luminance sensitivity loss not suspected with conventional perimetry. High spatial resolution perimetry also demonstrated reproducible areas of sensitivity loss in some glaucomatous eyes in areas of the visual field which appear normal with conventional programmes. The repeatability of the technique correlated with mean threshold sensitivity and was substantially improved to clinically acceptable levels by Gaussian filtering the thresholds. CONCLUSION: This technique of high spatial resolution perimetry allows the practical assessment of selected regions of the visual field at higher resolution than conventional perimetry, and may be clinically useful in glaucoma.

Further characterization of kindling antagonism.

Alternating stimulation of two sites in the forebrain culminates in typical kindling of generalized seizures from one site (dominant), whereas the other site (suppressed) supports only nongeneralized seizures for as long as stimulation of the dominant site continues, a phenomenon referred to as kindling antagonism. With the termination of stimulation of the dominant site, however, seizures provoked from the suppressed site eventually generalize, a progression thought to reflect the resumption of kindling from a previous point of arrest. To further assess the nature of kindling antagonism, we established antagonism between the amygdala and the septal area and subsequently evaluated the development of seizures provoked by stimulation of sites distal to the dominant site (always the amygdala). In Experiment 1, a 30-d stimulation-free period imposed after the establishment of antagonism failed to result in immediate generalization of seizures provoked from the suppressed site (septal area) in seven of eight rats. Although these results suggest that antagonism reflects an actual arrest of kindling rather than a transient inhibition of seizures, they are not entirely unambiguous: Rats exposed to the prolonged stimulation-free period required only half the number of septal stimulations for the expression of a generalized seizure as compared to rats receiving septal stimulation immediately after the establishment of antagonism. The latter finding is suggestive of a transient component of antagonism. In Experiment 2, development of generalized seizures from the previously naive right amygdala was virtually identical in rats previously kindled from the left amygdala and in rats expressing antagonism between the septal area and left amygdala. Development of generalized seizures from the right amygdala was faster than from the left amygdala in both groups of rats, however, suggesting that the expression of seizures provoked from the suppressed site after the establishment of antagonism does not involve a general impairment or enhancement of transfer. Experiment 3 revealed that radio-frequency lesions of the dominant site (amygdala) after the establishment of antagonism did not alter the subsequent development of generalized seizures from the suppressed site (septal area). This suggests that the expression of generalized seizures from the suppressed site after the establishment of kindling antagonism is not dictated by the functional state of the dominant site.