Diagnostic Accuracy of Technologies for Glaucoma Case-Finding in a Community Setting
Priya L. Dabasia, PhD, MCOPtom, l
Bruno R. Fidalgo, MSc, MOptom, l
David F. Edgar, FCOptom,1 David F. Garway-Heath, MD, FRCOphth, 2
John G. Lawrenson, PhD, FCOPtom
: To assess case-finding performance of the Frequency Doubling Technology Perimeter (FDT) (Carl Zeiss Meditec, Inc., Dublin, CA), Moorfields Motion Displacement Test (MMDT) (Moorfields Eye Hospital, London, UK), iVue optical coherence tomography (OCT) (Optovue Inc., Fremont, CA), and ocular response analyzer (ORA) (Reichert Ophthalmic Instruments, Depew, NY), alone or combined, for primary open-angle glaucoma (POAG).
: Cross-sectional, observational, community-based study.
: A total of 505 subjects aged 260 years recruited from a community setting using no predefined exclusion criteria.
: Subjects underwent 4 index tests conducted by a technician unaware of subjects’ ocular status. FDT and MMDT were used in suprathreshold mode. iVue OCT measured ganglion cell complex and retinal nerve fiber layer (RNFL) thickness. Reference standard was full ophthalmic examination by an experienced clinician who was masked to index test results. Subjects were classified as POAG (open drainage angle, glaucomatous optic neuropathy, and glaucomatous field defect), glaucoma suspect, ocular hypertension, or non-POAG/nonocular hypertension.
Main Outcome Measures:
Test performance evaluated the individual as the unit of analysis. Diagnostic accuracy was assessed using predefined cutoffs for abnormality, generating sensitivity, specificity, and likelihood ratios. Continuous data were used to derive estimates of sensitivity at 90% specificity and partial area under the receiver operating characteristic curve (AUROC) plots from 90% to 100% specificity.
: From the reference standard examination, 26 subjects (5.1 %) had POAG and 32 subjects (6.4%) were glaucoma suspects. Sensitivity (95% confidence interval) at 90% specificity for detection of glaucoma suspect/POAG combined was (28-55) for FDT, 35% (21-48) for MMDT, and (44-70) for best performing OCT parameter (inferior quadrant RNFL thickness); for POAG, sensitivity was 62% (39—84) for FDT, (37-78) for MMDT, and (68-98) for inferior quadrant RNFL thickness. Partial AUROC was significantly greater for inferior RNFL thickness than visual-function tests (P < 0.001). Post-test probability of glaucoma suspect/POAG combined and definite POAG increased substantially when best-performing criteria were combined for FDT or MMDT, iVue OCT, and ORA.
: Diagnostic performance of individual tests gave acceptable accuracy for POAG detection. Low specificity of visual-function tests precludes their use in isolation, but case detection improves by combining RNFL thickness analysis with visual function tests. Ophthalmology 2015;122:2407-2415 0 2015 by the American Academy of Ophthalmology.
|Open-angle glaucoma (OAG) is a major cause of visual morbidity, accounting for 10.6% to 13.5% of blindness in high-income countries. However, epidemiologic studies in developed countries consistently demonstrated that approximately half of those with OAG remained undetected using current case-finding strategies.
Open-angle glaucoma satisfies Wilson and Jungner’ s9 criteria for the condition and treatment ideally required to initiate a screening program. In 2012, a comparative effectiveness review by the Agency for Healthcare.
||Research and Quality concluded that limited evidence existed on the effectiveness of screening for OAG in adult populations. o An earlier UK-based economic modeling study reported that population screening at any age was not cost-effective, but stronger evidence existed in support of targeted screening of high-risk groups. ll A strategy for improving screening cost-effectiveness was proposed, involving initial technology-based assessment, allowing an enriched population to be referred for office-based assessment by an ophthalmologist or optometrist.
Anterior Segment Imaging Predicts Incident Gonioscopic Angle Closure
Mani Baskaran, DNB, Jayant V. lyer, MBBS, MMed,
Arun K. Narayanaswamy, DNB, MMed, Yingke He, Lisandro M. Sakata, MD, PhD, Renyi wu, MD, PhD, Dianna Liu, MD, Monisha E. Nongpiur, MD, David S. Friedman, MD, PhD, in Aung, FRCS(Ed), PhD
: To investigate the incidence of gonioscopic angle closure after 4 years in subjects with gonioscopically open angles but varying degrees of angle closure detected on anterior segment optical coherence tomography (AS OCT; Visante; Carl Zeiss Meditec, Dublin, CA) at baseline.
: Prospective, observational study.
: Three hundred forty-two subjects, mostly Chinese, 50 years of age or older, were recruited, of whom 65 were controls with open angles on gonioscopy and AS OCT at baseline, and 277 were cases with baseline open angles on gonioscopy but closed angles (1 —4 quadrants) on AS OCT scans.
: All subjects underwent gonioscopy and AS OCT at baseline (horizontal and vertical single scans) and after 4 years. The examiner performing gonioscopy was masked to the baseline and AS OCT data. Angle closure in a quadrant was defined as nonvisibility of the posterior trabecular meshwork by gonioscopy and visible iridotrabecular contact beyond the scleral spur in AS OCT scans.
Main Outcome Measures:
Gonioscopic angle closure in 2 or 3 quadrants after 4 years.
: There were no statistically significant differences in age, ethnicity, or gender between cases and controls. None of the control subjects demonstrated gonioscopic angle closure after 4 years. Forty-eight of the 277 subjects (17.3%; 95% confidence interval [Cl], 12.8—23; P < 0.0001) with at least 1 quadrant of angle closure on AS OCT at baseline demonstrated gonioscopic angle closure in 2 or more quadrants, whereas 28 subjects (10.1 %; 95% Cl, 6.7—14.6; P < 0.004) demonstrated gonioscopic angle closure in 3 or more quadrants after 4 years. Individuals with more quadrants of angle closure on baseline AS OCT scans had a greater likelihood of gonioscopic angle closure developing after 4 years (P < 0.0001 , chi-square test for trend for both definitions of angle closure).
: Anterior segment OCT imaging at baseline predicts incident gonioscopic angle closure after 4 years among subjects who have gonioscopically open angles and iaido-trabecular contact on AS OCT at baseline. Ophthalmology 2015;122:2380-2384 0 2015 by the American Academy of Ophthalmology.
Primary angle-closure glaucoma is a major cause of irreversible blindness in Asia, especially in people of Chinese ethnicity. The reference standard for angle assessment remains gonioscopy, which requires topical anesthesia and a contact lens and is cumbersome and time consuming. In fact, nearly half of those with diagnosed glaucoma have no documentation of gonioscopy in the medical charts, indicating that there are barriers to carrying out the examination.3 Anterior segment optical coherence tomography (AS OCT) is a noncontact technique for imaging the AS and iridocorneal angle and can be performed by a trained technician. We previously reported that AS OCT identified more eyes as having angle closure than gonioscopy. Although this finding could indicate a high false-positive rate for AS OCT, it also could be the case that AS OCT is better able to identify milder forms of angle closure than gonioscopy because no external illumination is required and no contact is made with the eye, which can cause angle widening. Furthermore, there may be low iridotrabecular contact just above the scleral spur that can be seen as angle closure on AS OCT but would appear to be open on gonioscopy. To determine whether those identified as closed on AS OCT have an increased risk of developing angle closure, we examined subjects with gonioscopically open angles but varying degrees of iridotrabecular contact as measured by AS OCT 4 years after the initial examination.
The study was approved by the institutional review boards of the Singapore Eye Research Institute and Johns Hopkins University and adhered to the tenets of the Declaration of Helsinki. All subjects provided written informed consent. The primary study population consisted of phakic subjects 50 years of age or older who were examined in a community-based study of Singaporeans visiting a government-based polyclinic for nonophthalmic medical problems in 2007.4
The study methodology and details of the study population have been described previously.