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Purpose To compare rim area rates in patients with and without the visual field (VF) progression endpoint in the Canadian Glaucoma Study and determine whether intraocular pressure (IOP) reduction following the endpoint altered rim area rate. Design Prospective multicenter cohort study. Methods setting: University hospitals. patient population: Two hundred and six patients with open-angle glaucoma were examined at 4-month intervals with standard automated perimetry and confocal scanning laser tomography. intervention: After the endpoint, IOP was reduced by ≥20%. outcome measures: Univariate analysis for change in rim area rate and multivariable analysis to adjust for independent covariates (eg, age, sex, and IOP). Results Patients with an endpoint (n = 59) had a worse rim area rate prior to the endpoint compared to those without (n = 147; median [interquartile range]: −14 [−32, 11] × 10 −3 mm 2 /y and −5 [−14, 5] × 10 −3 mm 2 /y, respectively, P = .02). In univariate analysis, there was no difference in rim area rate before and after the endpoint (median difference [95% CI], 8 (−10, 24) × 10 −3 mm 2 /y), but the muItivariate analysis showed that IOP reduction >2 mm Hg after the endpoint was strongly linked to a reduction in rim area rate decline (8 × 10 −3 mm 2 /y for each additional 1 mm Hg reduction). Conclusions Patients with a VF endpoint had a median rim area rate that was nearly 3 times worse than those without an endpoint. Lower mean follow-up IOP was independently associated with a slower decline in rim area.

Noncontact transscleral Nd:YAG laser thermal mode cyclocoagulation is known to reduce intraocular pressure (IOP). Thirty-five eyes were treated at a mean of 2.5 Joules and followed for a mean of 28 months. The mean preoperative IOP of 39.8 mmHg (standard deviation, 11.7) was consistently decreased by 45% to 55% over the follow-up period (standard deviation, 19.9 to 30.8), along with a significant reduction of medical therapy. This effect is comparable with that obtained by investigators using much higher energy levels. Successful control was defined as IOP between 5 and 21 mmHg for eyes with visual acuity of counting fingers or better, between 5 and 25 mmHg for eyes with hand motions to light perception, and as control of ocular pain for eyes with no light perception; 71 % to 75% of the eyes were successfully controlled for up to 3 years. The use of lower energy levels appears to be associated with a lower incidence of vision loss and, therefore, merits further controlled investigation.

Background: Despite strictly defined criteria for visual field progression in the ongoing Normal-tension Glaucoma Study, the authors noted a surprisingly large number of patients reaching the endpoint. Traditional methods could not be used to check the diagnostic accuracy of their criteria, because no "gold standard" was established for distinguishing true change from physiologic long-term fluctuation. Methods: The authors developed a statistical method based on the results of duplicate tests for progression in their subjects. This method allowed the authors to assess the sensitivity, specificity, and predictive values of their diagnostic criterion. It also estimated the true incidence of progression and provided standard errors for the estimates. Results: The authors found that their original strict criteria for progression, based on duplicate testing, produced false calls of progression 57% of the time. By raising the requirement for deterioration and by repeating the entire sequence of duplicate testing once more, the authors have successfully reduced the rate of false calls to 2%. Conclusion: Accuracy in recognizing progression is improved by not accepting small changes as evidence of progression and by confirming the findings on repeat testing.

Objectives To determine rates of visual field change associated with risk factors for progression in the Canadian Glaucoma Study (abnormal anticardiolipin antibody level, age, female sex, and mean follow-up intraocular pressure [IOP]), and to evaluate the effect of IOP reduction on subsequent rates of visual field change in progressing patients. Methods Two hundred sixteen patients (median age, 65.2 years) were followed up at 4-month intervals with perimetry and were monitored for progression. Patients reaching an end point based on total deviation analysis underwent 20% or greater reduction in IOP. Rates of mean deviation (MD) change were calculated. Results Patients with 0, 1, and 2 end points had a median of 18, 23, and 25 examinations, respectively. The median MD rate in progressing patients prior to the first end point was significantly worse compared with those with no progression (-0.35 and 0.05 dB/y, respectively). An abnormal anticardiolipin antibody level was associated with a significantly worse MD rate compared with a normal anticardiolipin antibody level (-0.57 and -0.03 dB/y, respectively). Increasing age was associated with a worse MD rate, but female sex and mean follow-up IOP were not. After the first end point, the median IOP decreased from 18.0 to 14.8 mm Hg (20% in individual patients), resulting in a significant MD rate change from -0.36 to -0.11 dB/y. Conclusions Patients with abnormal anticardiolipin antibody levels and increasing age had faster visual field change. Modest IOP reduction in progressing patients significantly ameliorated the rate of visual field decline. Trial registration clinicaltrials.gov Identifier: NCT00262626.

We reviewed stereo disc photographs of 232 control, ocular hypertensive and glaucomatous patients to assess the value of baring of the circumlinear vessel of the optic nerve head as a sign of glaucomatous damage. We found a significant correlation between the presence of this sign and the diagnosis. The sign is rarely false positive. There is a 35% false negative rate in eyes with a circumlinear vessel and known glaucomatous visual field defects. However, the presence of a circumlinear vessel gap sign is generally associated with nerve head damage and always deserves further evaluation.

There is a growing body of evidence that deficits in flicker sensitivity are an early symptom of glaucoma. For example, Tyler1 found a large subset of patients who showed deficits principally at middle temporal frequencies. An interesting clinical implication of this finding was that screening techniques measuring either CFF or sensitivity to low frequencies might miss glaucomatous defects in many individuals. We have collected data that are consistent with Tyler’s finding using multiflash campimetry, a computer implemented technique that allows temporal resolving power to be quantified by determining the duty cycle required to detect flicker. In this study, the ability to detect flicker at 5 and 15 Hz was compared in 20 retinal locations within the central 5°. Although all observers showed greater temporal resolving power at 5 Hz, compared with 15 Hz, performance differences were exacerbated for glaucoma suspects and even more so for glaucoma patients. One way of accounting for these and Tyler's results is to assume that flicker techniques are primarily sensitive to activity in nerve fibers possessing bandpass temporal characteristics with large bandwidths.

There is a growing body of evidence indicating that deficits in temporal sensitivity represent an early symptom of chronic open angle glaucoma (1-4). However, the methodologies typically employed favor detection within the achromatic system. The purpose of the present study was to begin to explore the extent to which temporal sensitivity in the chromatic pathways may be sacrificed in glaucoma. The initial strategy that was adopted entailed testing pure glaucoma patients and suspects who, with at least one eye, scored within the normal range on both the H-R-R Pseudoisochromatic Plates, and the Farnsworth-Munsell 100 Hue Test. In this way, we could also clearly assess the value of measuring temporal chromatic sensitivity as compared to the use of color discrimination tests conducted under steady-state luminance conditions.

Multi-flash campimetry is a computer-implemented technique used for the rapid assessment of temporal resolving power across the visual field. On the basis of previous reports that glaucoma patients exhibit impaired temporal sensitivity earlier than conventional perimetric field loss, the question of whether multi-flash campimetry might also be sensitive to the visual consequences of glaucoma was explored. Of the 27 patients that were tested, only one had normal temporal resolving power in both eyes, suggesting that multi-flash campimetry might be a useful aid in determining whether a patient should be diagnosed and treated as a glaucoma suspect or as a confirmed glaucoma patient.

Vision care professionals are exhibiting a growing interest in psychophysical testing. In the case of glaucoma, this may be partially due to the fact that the diagnosis and treatment can depend upon the results of these tests. For this reason, researchers have been exploring a variety of psychophysical techniques in order to determine visual loss at the earliest stages. The use of automated perimeters, for instance, has demonstrated that glaucomatous eye damage may be present before previously realized [1,2]. Other than light sensitivity thresholds, spatial and temporal aspects of vision have been found to be abnormal in glaucoma patients and suspects as well. A number of investigators have reported that contrast sensitivity, especially at low and medium frequencies, can be abnormal in glaucoma patients and suspects [3–8]. In the 1940s and 1950s [9–11], and more recently [12–14], loss of temporal resolving power and sensitivity has also been reported. Given that both spatial and temporal losses are observed in glaucoma, the question remains as to whether the same neural mechanisms underlie each.

Multi-flash campimetry is a technique in which temporal resolving power in 120 points of the visual field can be measured in about a half hour. It entails assessing the duty cycle (i.e., the proportion of a cycle that is lit) required to detect 5 Hz flicker. Two- and three-dimensional visual field plots can be created from the data that allow an easy identification of impaired regions. A comparison of multi-flash data and those from a temporal sensitivity experiment suggests that the amplitude of the fundamental Fourier frequency mediates flicker detection in both tasks and may provide a link between different tests that measure temporal aspects of vision. An example of how the amplitude of the fundamental can be used as the basis for quantitatively describing multi-flash data is given.

In Reply. —We are grateful for Dr Sommer's remarks about the neuroretinal rim area in patients with suspected and early chronic glaucoma and for the opportunity to make a few further observations in response. All of us are striving to find an "ideal" marker that would become abnormal before the onset of classic visual field defects and should also become positive before optic nerve damage and generalized axon loss occur. Such a marker would probably give us the best opportunity to take preventive measures at much earlier stages of damage. There is evidence that axons are lost diffusely in the retina before localized visual field loss occurs.1-4 There is also evidence that contrast sensitivity, 5 retinal receptive fieldlike functions, 6 color disturbance, 7 and overall loss of the differential threshold 8 precede localized visual field defects. In the case of color disturbances, this value has been shown to be predictive

• The cup-disc ratio is an indirect measure of the amount of neural tissue present at the optic nerve head. A large cup-disc ratio in a large disc may be accompanied by a normal neuroretinal rim. The area of the neuroretinal rim is relatively constant in normal persons and should relate to visual function. In 39 eyes of patients with suspected glaucoma, normal subjects, and patients with early open-angle glaucoma, biometric findings, psychophysical functions, and optic nerve measurements were studied. The area of the neuroretinal rim was determined from stereophotographs and corrected for the magnification by the optical components of the eye. A statistically significant relation between this neuroretinal area and parameters of visual function was found. The cup-disc ratio correlated more weakly with visual function. Covariant analysis showed the neuroretinal area to be the only parameter capable in our sample of discriminating among the three clinical groups.