Glaucomatous Field Defects Research Articles

Performance of advanced technologies for community‐based glaucoma case‐finding

AbstractPurpose To identify if the Frequency Doubling Technology perimeter (FDT), Moorfields Motion Displacement Test (MDT), iVue Optical Coherence Tomographer (OCT) and Ocular Response Analyser (ORA), alone or in combination, improve case detection of primary open angle glaucoma (POAG) in a population aged over 59 years.Methods 505 volunteers aged 60 to 92 years (median age 68) completed all 4 screening tests conducted without knowledge of subjects’ ocular status. FDT and MDT were used in suprathreshold mode. iVue OCT measured ganglion cell complex and retinal nerve fibre layer thickness. Each subject then received a full ophthalmic examination by an experienced clinician, masked to preceding test results. Based on this evaluation, subjects were classified as normal, glaucoma suspects or POAG (defined as an open drainage angle, glaucomatous optic neuropathy, and glaucomatous field defects).Results Based on the reference standard examination, 26 (5.1%) subjects were classified as POAG, and 32 (6.4%) suspect glaucoma. Sensitivity at 90% specificity for detection of POAG was 63% (95% CI: 39 to 82) for FDT, 54% (33 to 74) for MDT, and 82% (64 to 95) for best performing OCT parameter (inferior RNFL thickness). Using these criteria, partial AUROC was significantly greater for inferior RNFL thickness than other tests (p=<0.01).The probability of having POAG increased substantially when best‐performing criteria were combined for perimetry, iVue OCT and ORA.Conclusion Diagnostic performance of individual tests gave acceptable accuracy for POAG detection in a representative sample of elderly subjects. For case‐finding, our study supports combining retinal nerve fibre layer thickness analysis with performance on vision‐function tests.

Frequency-Doubling Technology Perimetry for Detection of the Development of Visual Field Defects in Glaucoma Suspect Eyes

While standard automated perimetry (SAP) remains the reference standard for evaluation of visual field (VF) defects in glaucoma, this study demonstrates that frequency-doubling technology (FDT) perimetry is effective in monitoring visual field progression and may detect the onset of visual field defects earlier than SAP. To compare detection of the development of VF defects, rate of change of VF loss, and risk factors for progression between SAP and matrix FDT perimetry in glaucoma suspect and ocular hypertensive eyes. A total of 113 glaucoma suspect and ocular hypertensive eyes from 76 patients with normal SAP and FDT perimetry results at baseline were prospectively followed up for SAP and FDT perimetry testing at approximately 4-month intervals for 30 months or longer. Patients were consecutively enrolled and followed up from January 2, 2008, to February 28, 2012, at the Hong Kong Eye Hospital, Chinese University of Hong Kong. Visual field progression was defined by the development of VF defects confirmed by 3 or more consecutive examinations at a cluster of 3 or more (less conservative) or 4 or more (more conservative) locations. The rates of change of mean deviation and pattern standard deviation were evaluated with linear mixed models and the risk factors for VF progression were computed with Cox proportional hazard models. During a median study period of 3.4 years, 8.0% of eyes developed VF defects detected by FDT perimetry, 6.2% by SAP, and 4.4% by both using the less-conservative criteria. The detection dropped to 6.2%, 4.4%, and 2.7%, respectively, when the more-conservative criteria were applied. The rate of change of pattern standard deviation was significantly faster for FDT perimetry than SAP (P < .001). Baseline average retinal nerve fiber layer thickness and the number of clock hours of abnormal retinal nerve fiber layer measurement were associated with increased risk for VF progression for both SAP and FDT perimetry. Frequency-doubling technology perimetry would be useful to monitor the onset of VF defects in glaucoma and may detect VF defects not evident in SAP.

Evaluation of Hemifield Sector Analysis Protocol in Multifocal Visual Evoked Potential Objective Perimetry for the Diagnosis and Early Detection of Glaucomatous Field Defects

PurposeMultifocal visual evoked potential (mfVEP) is a newly introduced method used for objective visual field assessment. Several analysis protocols have been tested to identify early visual field losses in glaucoma patients using the mfVEP technique, some were successful in detection of field defects, which were comparable to the standard automated perimetry (SAP) visual field assessment, and others were not very informative and needed more adjustment and research work. In this study we implemented a novel analysis approach and evaluated its validity and whether it could be used effectively for early detection of visual field defects in glaucoma.MethodsThree groups were tested in this study; normal controls (38 eyes), glaucoma patients (36 eyes) and glaucoma suspect patients (38 eyes). All subjects had a two standard Humphrey field analyzer (HFA) test 24-2 and a single mfVEP test undertaken in one session. Analysis of the mfVEP results was done using the new analysis protocol; the hemifield sector analysis (HSA) protocol. Analysis of the HFA was done using the standard grading system.ResultsAnalysis of mfVEP results showed that there was a statistically significant difference between the three groups in the mean signal to noise ratio (ANOVA test, p < 0.001 with a 95% confidence interval). The difference between superior and inferior hemispheres in all subjects were statistically significant in the glaucoma patient group in all 11 sectors (t-test, p < 0.001), partially significant in 5 / 11 (t-test, p < 0.01), and no statistical difference in most sectors of the normal group (1 / 11 sectors was significant, t-test, p < 0.9). Sensitivity and specificity of the HSA protocol in detecting glaucoma was 97% and 86%, respectively, and for glaucoma suspect patients the values were 89% and 79%, respectively.ConclusionsThe new HSA protocol used in the mfVEP testing can be applied to detect glaucomatous visual field defects in both glaucoma and glaucoma suspect patients. Using this protocol can provide information about focal visual field differences across the horizontal midline, which can be utilized to differentiate between glaucoma and normal subjects. Sensitivity and specificity of the mfVEP test showed very promising results and correlated with other anatomical changes in glaucoma field loss.

Determinants of severity at presentation among young patients with early onset glaucoma

Aim:The aim of this study was to evaluate the clinical, socio-economic, and demographic factors associated with the severity at presentation among juvenile primary open angle glaucoma (JOAG) patients.Materials and Methods:Age at diagnosis, family history, baseline intraocular pressure (IOP), access to health-care, socio-economic status, and glaucoma awareness among 80 unrelated JOAG patients presenting between 10 years and 40 years of age were analyzed for their association with the severity at presentation. Severity at presentation was graded based on worse eye visual field using the advanced glaucoma intervention study score and on binocular visual field defects at presentation.Results:Patients with a positive family history presented 4 years earlier (P = 0.045, confidence interval [CI]: 0.09-8.8) compared to those without a family history. Lower socio-economic status (Odds ratio [OR] 5.7, P = 0.01, CI: 1.5-22), and higher baseline IOP (OR 7, P = 0.003, CI: 1.9-26) were associated with severe glaucomatous visual field defect at presentation. A negative family history was associated with a 10 times likelihood of presenting with a severe glaucomatous field defect (OR 0.1, P = 0.007, CI: 0-0.5).Conclusions:Clinical, socio-economic, and demographic factors are contributory to the severity at presentation among young patients with early onset glaucoma. Presence of a family history is associated with an earlier presentation among these patients and a reduced risk of the severe presentation.

Retinal Ganglion Cell Count Estimates Associated with Early Development of Visual Field Defects in Glaucoma

To estimate retinal ganglion cell (RGC) losses associated with the earliest development of visual field defects in glaucoma. Observational cohort study. The study group included 53 eyes of 53 patients with suspected glaucoma who were followed as part of the Diagnostic Innovations in Glaucoma (DIGS) study. These eyes had normal standard automated perimetry (SAP) visual fields at baseline and developed repeatable (3 consecutive) abnormal test results during a median follow-up of 6.7 years. An age-matched control group of 124 eyes of 124 healthy subjects recruited from the general population was included. Estimates of RGC counts were obtained using a previously published model that combines estimates of RGC numbers from SAP sensitivity thresholds and retinal nerve fiber layer (RNFL) thickness measurements with spectral domain optical coherence tomography (SD-OCT). For eyes converting to glaucoma, estimates of RGC counts were obtained at the time (within ± 3 months) of the first abnormal visual field, representing the time of earliest detection of visual field losses. Estimates of RGC counts in eyes converting to glaucoma versus healthy eyes. The average RGC count estimate in the eyes with early visual field defects was 652057 ± 115829 cells, which was significantly lower than the average of 910 584 ± 142 412 cells found in healthy eyes (P < 0.001). Compared with the average number of RGCs in the healthy group, glaucomatous eyes had an average RGC loss of 28.4%, ranging from 6% to 57%, at the time of the earliest visual field defect on SAP. Retinal ganglion cell counts performed significantly better than the SD-OCT average RNFL thickness parameter in discriminating glaucomatous from healthy eyes with receiver operating characteristic curve areas of 0.95 ± 0.02 versus 0.88 ± 0.03, respectively (P = 0.001). Glaucomatous eyes with the earliest detectable visual field loss on automated perimetry may already show substantial loss of RGCs. Empirical estimates of RGC counts combining structural and functional tests agreed closely with previous histologic reports on the number of RGCs associated with early visual fields defects on SAP.

The water-drinking test: a review

The water-drinking test (WDT) was first described as a diagnostic tool for glaucoma, which was later abandoned due to its poor diagnostic accuracy. This test has gained significant interest in recent years as different studies have shown its use as a surrogate for detecting patients who have intraocular pressure (IOP) spikes not detected during regular office hours. According to peer-reviewed literature, IOP peak detected by the WDT positively correlates with the severity of visual field defects in glaucoma and may be predictive of visual field progression. It was demonstrated that IOP peaks during the WDT are correlated and are in agreement with IOP peaks that normally occur during the day. The WDT has also been used to evaluate the quality of different clinical and surgical treatment options in glaucoma. The main objective of this article is to present and discuss these evidences and the applicability of the WDT as an assessment tool for glaucomatous disease.

Comparison Between MP-1 and Humphrey Visual Field Defects in Glaucoma and Retinitis Pigmentosa

To compare MP-1 microperimeter and Humphrey Field Analyzer (HFA) defects, in patients with retinitis pigmentosa (RP), a disease primarily affecting the photoreceptors, and in patients with glaucoma, a disease primarily affecting postreceptoral ganglion cells, and to analyze the similarities and differences between the results. Eleven patients (11 eyes) with RP and 10 patients (10 eyes) with primary open-angle glaucoma (OAG) underwent MP-1 and HFA visual field testing (10-2 pattern). All tested eyes had defects encroaching within 10° of fixation. MP-1 total deviation (TD) probability defects, derived from a previously collected normative database of 50 subjects, were compared to HFA TD defects and to the local defect map of the MP-1. Test duration was compared between instruments. In RP patients, MP-1 scotomata were deeper and wider than HFA defects; however in OAG, the opposite was observed. Examination duration in both patient groups was 12 to 14 min for the MP-1 and 6 min for the HFA. The MP-1 local defect map tended to overestimate defects compared to the MP-1 TD analysis. The differences in results between the MP-1 and HFA for the two groups of patients with RP and OAG can be attributed to the different adaptation levels and to the dynamic range of test lights available for the two instruments. The clinician should also be aware of the possible consequences of the differences in the method of derivation of normative data for the two instruments, as this may affect the interpretation of visual field results.

Pathogenesis of Arcuate Field Defect in Glaucoma

Pathogenesis of Arcuate Field Defect in Glaucoma

Natural History of Open-Angle Glaucoma

This article, based on the Early Manifest Glaucoma Trial (EMGT), provides prospective natural history data on progression of glaucomatous field defects in 3 of the most common glaucoma types. Cohort of EMGT patients randomized to the untreated control group and followed up to the time of progression, when treatment could be initiated. We evaluated 118 control patients: 46 with high-tension glaucoma (HTG), 57 with normal-tension glaucoma (NTG), and 15 with pseudoexfoliation glaucoma (PEXG). Visual fields were tested every 3 months with the Humphrey 30-2 Full Threshold test program. Linear regression analyses of the perimetric mean deviation (MD) values were performed, and the rate of progression was defined as the regression coefficient in decibels per year. Percentages of progressed eyes and time to progression were determined using EMGT event-based predetermined progression criteria derived from Glaucoma Change Probability Maps. The median and interquartile rates of visual function loss were -0.40 (1.05) dB/year overall and -0.46 (1.61) in HTG, -0.22 (0.65) in NTG, and -1.13 (6.13) in PEXG. Thus, interpatient variability was large. Mean rates were considerably higher than medians: -1.08 dB/year overall, -1.31 in HTG, -0.36 in NTG, and -3.13 in PEXG. Differences in median visual function progression rates among groups were statistically significant (NTG vs. HTG, P = 0.003; PEXG vs. non-PEXG, P<0.001). Progression was considerably and significantly faster in older than in younger patients (P = 0.002). By 6 years, 68% of patients had progressed overall, 74% of those with HTG, 56% of those with NTG, and 93% of those with PEXG (P = 0.012). Median time to progression also differed considerably among groups: 19.5 months in PEXG, 44.8 months in HTG, and particularly 61.1 months in NTG (P<0.0001). In this 6-year follow-up study, the median untreated rate of progression corresponded to advancing from normal visual function to blindness in approximately 70 years, whereas on the basis of the mean rate, visual function would show the same deterioration in approximately 25 years. Large differences existed among patients and different glaucoma types, with PEXG progressing considerably faster than HTG, and NTG progressing at the lowest rate.

Fitness to drive in glaucoma patients‐ Preliminary study results

Abstract Purpose To develop a useful binocular 30° visual field criterion to predict safe driving behaviour in glaucoma patients by comparing perimetric data with an actual driving test on the road. Methods The sample will consist of 200 driving glaucoma patients, recruited in 2 university based glaucoma clinics (Ghent and Leuven, Belgium). Inclusion criteria are glaucomatous optic disc damage and/or glaucomatous field defects. Exclusion criteria are concomitant ocular disease, cataract &gt; LOCS 2, systemic disease or medication affecting the visual field. Data collection will include demographic and medical data, driving habits, and Mini Mental Status. A complete ophthalmic examination wil be done including Goldmann, SAP and Esterman visual field testing. In addition, UFOV test, stereopsis and contrast sensitivity testing will be performed. All subjects will perform an on the road driving test with a driving expert of the Belgian Institute for Traffic Safety. Subjects can pass, fail, or pass the test with limitations. An attempt will be made to develop an algorithm of visual field abnormalities that predict as accurately as possible the outcome of the practical driving test. Results Preliminary results of the first 50 included patients will be presented.

381 Un suivi à long terme des effets des béta-bloquants sur les patients atteints de glaucome

The purpose of this prospective, comparative, non randomized study was to evaluate the influence of betaxolol and timolol on the visual function and IOP in the patients with primary open angle glaucoma. The study was performed in the University Eye Clinic Sarajevo in the period from June 2003 to March 2005. 20 patients were treated with 0,25% betaxolol, and 23 patients were treated with 0,5% timolol. Of this 43 patients, 33 could be followed up in a 35 months period. Inclusion criteria: subject >35 years old with POAG; both eyes of subjects followed through study, patients with glaucomatous field defect on Octopus, CLV> 4 dB; no visual acuity less than 0,4 and IOP>21mmHg. Exclusion criteria: patients with systemic disease, pathologic myopia, ocular disorders, and those with contraindication to beta-blockers, neurological disease, eye and head trauma previously. Each examination included visual field measurement, slit lamp examination, intraocular pressure, fundoscopy, blood pressure measurement. Automated perimetry was performed with Octopus G1 program (baseline, 6, 12, 18, 35 month). Of the 43 patients initially enrolled, 10 patients discontinued treatment. Patients were initially comparable in terms of IOP, MS and MD. Both drug lowered IOP. The reduction in IOP in timolol treated group was more pronounced than in the group of patients treated with betaxolol, but the difference was not statistically significant. The visual field improved during the first 12 months and remained more or less stable for the rest of observation period. Patients treated with betaxolol had statistically significant lower averaged mean defects (p<0,05). We may suppose that selective beta 1-blockers have better effects on blood flow of optic nerve head than non-selective beta-blockers and on that way protect ganglion cells and nerve fibers. That in suggested after analysis of visual field. In few publication were publicized some results as we have found but this neuroprotective effect was not explained. The treatment of glaucoma patients is a challenge. It is well known that elevated IOP is a risk factor for progressing visual field damage. Despite well-controlled IOP, visual field damage could be find. Our results indicate that locally applied beta-blockers are reducing IOP over a long period. Timolol tended to have a better effect on IOP than did betaxolol, but betaxolol had a better influence on the visual field.

Classifying Patterns of Localized Glaucomatous Visual Field Defects on Automated Perimetry

To classify the classic patterns of glaucomatous visual field defects on automated perimetry and to study their proximity to fixation. Cross-sectional observational study. About 1120 full threshold 30-2 reliable visual fields of glaucoma patients were analyzed by 2 glaucomatologists. Classically described patterns of visual field defects were identified on the pattern deviation plot and definitions proposed. Interreader agreement between 3 independent (not involved in the classification) readers was determined. Proximity to fixation of the different patterns was assessed. Interreader agreement with 3 readers was found to be 93% or more between any 2 readers using the present system of classification. Central fixation was seen to be involved in 45% of the glaucomatous visual field defects studied overall. The proposed definitions of topographical glaucomatous field defects based on the pattern deviation probability plot are simple to use in clinical practice with good interreader agreement.

Cost‐effectiveness analysis in glaucoma: what drives utility? Results from a pilot study in Sweden

To investigate the effect of different levels of visual field defect in glaucoma on utilities and to test if utilities could be assessed using a general questionnaire such as the EQ-5D. A cross-sectional study in 199 patients with ocular hypertension or open-angle glaucoma grouped into 5 severity stages according to visual field defects was performed in 4 specialized ophthalmic centres. Descriptive analysis was performed for the sample and by stage, and the effect of vision loss on utility was investigated with multiple step-wise regression analysis. The mean age of the sample was 70 and the mean MD in the worse eye was -13.1 dB (SD 10.2). Visual acuity (VA) was 0.63 and 0.87 in the worse and better eye, respectively, and the mean utility was 0.80 (SD 0.23). Utility decreased with increasing glaucomatous damage, ranging from 0.84 for mild disease to 0.72 for severe damage (MD -2.5 to -28.1), but the difference between the groups was not statistically significant when controlling for co-morbidity, except for the most severe stage (p < 0.01). In multiple regression analysis, visual field in the better eye was significantly correlated with utility, and there was an indirect correlation between visual field in the worse eye and utility: the effect of total VA on utility was significant, and MD in the worse eye was correlated with total VA. Utility is strongly correlated with overall vision. Our results suggest a relationship between glaucomatous damage and utility, and patients with severe damage have a significantly lower utility. However, this should be further investigated in larger samples that include more patients with moderate-severe bilateral damage.

Heidelberg Retinal Tomograph (HRT 2) Parameters in Primary Open Angle Glaucoma and Primary Angle Closure Glaucoma: A Comparative Study in an Indian Population

Aims: To compare the Heidelberg Retinal Tomograph (HRT 2) parameters in patients with primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG) in an Indian population. Materials and Methods: Two groups of patients were recruited: group I comprised 78 eyes (78 patients) with POAG and group II 58 eyes (58 patients) with PACG. Based on visual field defects detected by automated perimetry, the groups were further classified into early, moderate, and severe glaucoma. All patients underwent a complete ophthalmic examination as well as an HRT 2 examination. The HRT parameters for the two groups were compared and the sensitivity and specificity of the parameters calculated. Results: All HRT parameters were similar in both groups: 85.9% (95% CI: 78.2, 93.6) of POAG and 81% (95% CI: 72.3, 89.3) of PACG had a positive F. S. Mikeleberg (FSM) discriminant function. Considering outside normal limits and borderline as abnormal, the Moorefield regression analysis had 83.3% (95% CI: 75, 91.6) sensitivity in POAG and 75.9% (95% CI: 64.9, 86.9) in PACG. In early POAG, the FSM discriminant function had a sensitivity of 74.3% (95% CI: 59.8, 88.8) compared to 58.3% (95% CI: 38.9, 77.7) for early PACG. The cup shape measure (p = 0.018) and the Moorfield regression analysis (p = 0.011) had significantly higher sensitivity for early POAG than for early PACG: cup shape measure sensitivity 62.9% (95% CI 46.9, 78.9) for early POAG versus 33.3% (95% CI: 14.4, 52.2) for early PACG and Moorefield regression analysis 74.3% (95% CI: 59.8, 88.8) versus 45.8% (95% CI: 39.9, 65.7). Conclusions: HRT has moderate sensitivity in the detection of damage leading to glaucomatous field defects. The sensitivity of HRT for early PACG appears to be less than that for early POAG. This may indicate a difference in pathophysiology.

Statistical evaluation of the diagnostic accuracy of methods used to determine the progression of visual field defects in glaucoma

To evaluate trend-type analyses to judge the progression of visual field damage (VFD) of glaucoma in terms of ratios of making judgments of progression and specificity, and to report a new method. Retrospective analysis of visual field (VF) results of actual glaucoma cases and those simulated by computer, and receiver operating characteristic curve analysis of performance of methods to judge the progression of VFD. One hundred five eyes of 105 open-angle glaucoma (OAG) patients with progressing VFD and 355 eyes of 355 clinically stable OAG patients for VF simulation from 4 university-based referral practices. Methods using regression analysis of total deviation (TD), mean deviation (MD), mean TD of a sectored VF, and original scoring used in the Advanced Glaucoma Intervention Study (AGIS) were compared. A VF test was repeated twice in a short period on the 355 stable OAG eyes, and test-retest fluctuation, including variance at each test point and covariance between 2 test points, was calculated to simulate stable glaucomatous VF series by computer. The sensitivity of each method was calculated with 105 progressing VF series, and specificity was calculated with 10,000 simulated stable glaucomatous VF series. Sensitivity (ratios of making judgments of progression), specificity, and diagnostic power. The methods using the TD slope on one test location showed a sensitivity of 0.848 to 1.000, with a specificity of 0.105 to 0.721, and on 2 adjacent test locations showed a sensitivity of 0.848, with a specificity of 0.722. A significant negative MD slope with P<0.05 showed a sensitivity of 0.524, with a specificity of 0.945. The method using a sectored VF showed a sensitivity of 0.695, with a high specificity of 0.946. The AGIS method showed a sensitivity of 0.305 to 0.467, with a very high specificity of 0.999 to 1.000. The method using previously reported mathematically sectored VFs showed a sensitivity of 0.790, with a specificity of 0.900, and higher diagnostic power (1.69) than the others in this study population. Most of the methods using the TD slope were characterized by high sensitivity, the AGIS method had a very high specificity, and those using VF sectors had reasonable sensitivity and specificity.

Validation of test duration as a screening criterion for frequency doubling perimetry

PurposeTo validate the test duration in frequency doubling perimetry as an independent criterion to screen for glaucomatous field defects. DesignProspective cross-sectional study MethodsGroup I included 85 eyes (85 patients) with established field defects on automated perimetry. Group II comprised 41 normal eyes (41 subjects). Both groups underwent Swedish interactive testing algorithm standard tests as well as frequency doubling perimetry (C20-1). A cutoff level of 90 seconds was used to calculate test duration sensitivity and specificity. We also categorized patients into those who took ≤90 seconds or less and those who took >90 seconds to complete the test and compared frequency doubling perimetry (any two abnormal points) with Swedish interactive testing algorithm in these groups. ResultsDuration of the test >90 seconds had 97.5% specificity with 62.3% sensitivity. Eleven subjects with glaucoma completed test in <91 seconds). ConclusionTest duration alone has a limited value in screening for glaucoma.

Sensitivity and specificity of the swedish interactive threshold algorithm for glaucomatous visual field defects

Purpose To determine the sensitivity and specificity of two new visual field algorithms in detecting glaucomatous visual field defects: (1) Swedish interactive threshold algorithm (SITA) standard and (2) SITA fast. Design Prospective observational case series. Participants Ninety normal subjects and 82 glaucoma patients. Testing Central 30° fields were performed with the Humphrey visual field analyzer 30-2 program (Humphrey Systems, Dublin, CA) using full threshold, SITA standard, and SITA fast algorithms on the same day for two or more sessions within a 1-month period. Main outcome measures Sensitivity and specificity in detecting glaucomatous visual field defects with SITA standard and SITA fast using full threshold testing as the reference standard. Results The sensitivity of SITA standard and SITA fast in detecting glaucomatous defects overall was 98% and 95%, respectively. In the subset of mild glaucomatous field defects (26 patients), sensitivity of SITA standard was 92% versus 85% with SITA fast. Sensitivity was 100% for both algorithms in moderate to severe glaucomatous defects. Specificity for glaucoma defects using SITA standard and SITA fast was 96% for both algorithms. SITA standard reduced test-taking time from full threshold by 52% in normal subjects and 47% in glaucoma patients ( P < 0.001). SITA fast reduced test-taking time by 72% in normal subjects and 65% in glaucoma patients ( P < 0.001). Mean deviation values were 0.4 dB and 0.8 dB better in SITA standard and SITA fast fields, respectively, in normal subjects ( P < 0.001), and 0.7 dB and 1.2 dB in SITA standard and SITA fast fields, respectively, in glaucoma patients ( P < 0.001) compared with full threshold values. Conclusions The new algorithms for measuring visual fields, SITA standard and SITA fast, have excellent sensitivity and specificity for glaucomatous visual field loss with considerable savings in time.

Lack of long-term drift in timolol’s effectiveness in patients with ocular hypertension: Bengstsson B, Heijl A. Invest Ophthalmol Vis Sci 2001;42:2839–2842

The authors reported the change over time in intraocular pressure in patients treated with topical timolol or placebo. Ninety patients with untreated ocular hypertension, defined as elevated intraocular pressure and normal visual fields, were randomly assigned to treatment and prospectively observed at three-month intervals for up to ten years in a double-masked fashion. The study end point was one eye showing reproducible glaucomatous field defects; patients were also withdrawn if one eye showed intraocular pressure of 35 mm Hg or higher. For each treatment group and visit, the mean and median of all intraocular pressure measurements were calculated. Medians were also calculated for the timolol group, assuming a worst-case scenario in which all patients who reached the end point, or intraocular pressure of 35 mm Hg. or more, were assumed to show higher intraocular pressure than those remaining in the study. Distributions of slopes for intraocular pressure over time were compared between treatment groups. Means and medians of follow-tip intraocular pressure over time did not differ between timolol- and placebo-treated patients. This was also true when assuming a worst-case scenario. Slopes of intraocular pressure over time did not differ statistically between treatment groups. In agreement with other masked and controlled studies and in conflict with uncontrolled ones, the authors conclude that their present study did not demonstrate long-term drift of intraocular pressure in patients with ocular hypertension treated with topical timolol.—Thomas J. Liesegang

Association of retinal vessel caliber and visual field defects in glaucoma

PURPOSE: This study evaluates the asymmetry of peripapillary retinal vessel caliber between inferior and superior hemispheres in eyes with visual field defects predominantly in one hemifield. DESIGN: Observational case series. METHODS: In a retrospective study, 64 eyes of 64 patients with primary open-angle glaucoma who had a marked difference in visual field defects between hemifields and who had no history of diabetes, trauma, or vascular occlusive disease were studied. The diameters of the superior and inferotemporal vessels were measured at the optic disk border with calipers on an enlarged image. RESULTS: In 64 eyes, the average ratio of the superior temporal artery diameter to inferotemporal artery diameter was significantly greater in the eyes with predominantly superior visual field defects as compared with those with inferior defects (1.10 ± 0.22 vs. 0.92 ± 0.19, respectively, P = .002, two-tailed t test). This indicates that the arteriole corresponding to the hemifield with the greater visual field defect was narrower than the arteriole in the other hemifield. This relationship was confirmed using χ 2 analysis ( P = .002) comparing the proportions of eyes with ratios greater or less than normal vessel caliber ratios (normal ratio = 0.95 from data reported by Jonas and associates to the location of the dominant field defect. No statistically significant relationship was detected between retinal vein diameter and localized visual field defects, as determined by both the unpaired t test and χ 2 analysis. CONCLUSION: In eyes with primary open-angle glaucoma, this study demonstrates a strong association between decreased peripapillary arteriole diameter and visual field defects in the corresponding hemifield. This reflects either an ischemic basis for glaucomatous damage or vascular constriction when there are fewer axons to nourish.

PEE8: FOUR YEAR COST-EFFECTIVENESS OF INITIAL TRABECULECTOMY VERSUS CONVENTIONAL THERAPY IN PRIMARY OPEN-ANGLE GLAUCOMA (POAG)

OBJECTIVES: To determine the cost-effectiveness of the primary treatment of primary open-angle glaucoma (POAG) with trabeculectomy versus conventional therapy. METHODS: A four-year incremental cost/quality-adjusted life year (QALY) model (year 2000 US dollars) of POAG using a societal perspective; including direct and indirect costs with a 3% annual discount rate for the base case. In the Glasgow trial, patients newly diagnosed with POAG with an intraocular pressure of 26mmHg and/or with glaucomatous field defects were randomized to trabeculectomy or conventional therapy (up to three medications). In the trabeculectomy branch, patients would either be 1) controlled without extra medication, 2) controlled with extra medication or 3) die from natural causes. Annual chance nodes for the conventional were 1) controlled by medication, 2) surgery or 3) death from natural causes. QALYs were calculated assuming a decline in utility would accompany loss in visual field. A 65-year old patient with a 5% rate of decline in utility was used as the base case. Sensitivity analyses were performed on the rate of utility decline, cost of medications, trabeculectomy cost, and discount rate. RESULTS: For the base case, the cost of initial trabeculectomy was $8316 versus $6339 for conventional therapy. The incremental cost was $1977 and the incremental QALY was 0.08, with ICE ratio of $24,830/QALY. CONCLUSIONS: Initial trabeculectomy is cost-effective for POAG. The model was most sensitive to the rate of decline in utility (<2%) and robust to changes in the costs of medications and trabeculectomy. Limitations include the lack of long-term clinical and QALY data on glaucoma patients with different treatments. Currently the standard of practice in the US is to start with conventional therapy for patients with moderate or severe glaucoma. Our results indicate that trabeculectomy may be a cost-effective option for these patients.