Blue-on-yellow perimetry can predict the development of glaucomatous visual field loss

What limits detection and resolution of short-wavelength sinusoidal gratings across the retina?

Peripheral resolution acuity for achromatic gratings is known to be limited by the density of the underlying ganglion cell sampling array. After confirming isolation of the short-wavelength sensitive (SWS) system using chromatic adaptation methods, we wished to determine if resolution is limited by blue/yellow ganglion cell sampling (evidenced by a superiority of detection over resolution acuity and the perception of aliasing) and thus directly related to SWS-driven ganglion cell density. We measured detection and resolution acuity between 0 degrees and 35 degrees, using blue sinusoidal gratings superimposed on a yellow adapting background which ranged in intensity from 2.5 to 4.7logTrolands. At all locations, a break could be observed in the acuity vs. illumination curves followed by a plateau. Detection and resolution acuity were the same for low background intensities, but resolution acuity was lower than detection at higher intensities, accompanied by observations of chromatic aliasing. SWS resolution is sampling-limited across the retina and agrees well with predicted performance based on anatomical estimates of small bistratified ganglion cell density.

Colour contrast sensitivity in ocular hypertension. A five-year prospective study

PURPOSE

To evaluate a peripheral colour contrast sensitivity test as a tool for early diagnosis of glaucoma in a five-year prospective study.

PATIENTS AND METHODS

Peripheral colour contrast sensitivity was measured with a computer graphics system developed by Arden et al. The test colours were varied along the protan, deutan and tritan colour confusion axes on a scale from 0 to 100 percentage units. Fifty-five ocular hypertensive (OH) patients examined with the colour contrast test, stereoscopic photography of the optic discs, and measurements of visual fields (Humphrey 24-2 glaucoma hemifield test (GHT)) in 1994, were re-examined after five years.

RESULTS

Ten patients were 'outside normal limits' in the GHT at follow-up. This group of 10 patients did not differ in colour contrast thresholds at the test in 1994 from the 45 who were still 'normal' (or 'borderline') at follow-up. Neither were there proportionally more patients with GHT 'outside normal values' for the patients with high colour contrast thresholds (> 30% units) in 1994 regarding any of the three colour axes. As judged from patient files, 27 patients had developed glaucoma during follow-up. Although there were differences between these 27 glaucoma patients and the remaining OH group at the colour contrast test in 1994, these differences did not reach statistical significance for any of the colour axes (largest difference in the tritan axis: 6.2% units, P = 0.0745). At follow-up, however, there was a significant difference in colour contrast for the protan axis between the clinical glaucoma group and the OH group (6.7% units, P = 0.0105).

CONCLUSION

The method used for colour contrast measurement did not reveal glaucomatous changes before conventional perimetry (Humphrey 24-2, GHT). Neither did it predict the patients who, in our clinic, subsequently developed glaucoma during a five-year period. A change over time in colour contrast in the protan axis for an OH patient may, however, indicate glaucoma development.

Standard achromatic perimetry, short wavelength automated perimetry, and frequency doubling technology for detection of glaucoma damage

OBJECTIVE

Reevaluation of the relationship between short wavelength automated perimetry (SWAP), standard achromatic perimetry (SAP), and frequency doubling technology (FDT) in glaucoma and ocular hypertensive patients and in glaucoma suspects.

DESIGN

Prospective comparative observational study.

PARTICIPANTS

Four age-matched groups were evaluated (42 patients with early to moderate glaucoma, 34 ocular hypertensives, 22 glaucoma suspects, and 25 normal controls) using SAP, SWAP, and FDT.

INTERVENTION

All participants underwent full clinical ophthalmologic evaluation followed by SWAP, SAP, and FDT perimetry within a period of not more than 3 months. Mean defect (MD), pattern standard deviation (PSD), visual field (VF) indices, and the percentage of depressed visual field points with P value <5% and <1% in the pattern deviation plot were evaluated.

MAIN OUTCOME MEASURES

For each of the four study groups, the MD, PSD, and the percentage of abnormal points significantly depressed <5% and <1% were compared for the three VF testing modalities.

RESULTS

In the glaucoma group, the mean percentage of the total number of abnormal points in SWAP was significantly less than abnormal points in SAP and FDT, both for 5% (P values were 0.0001 and 0.0001, respectively) and 1% (P values were 0.0001 and 0.0001, respectively). The same applied to the ocular hypertensives group. However, in the suspects group, no significant difference was detected. In normal controls, the abnormal points in SWAP were significantly lower than those in SAP for 5% (P value was 0.01) and 1% (P value was 0.05). FDT detected significantly larger defects (percentage of points <5%) than SAP in ocular hypertensives and suspects (P values were 0.01 and 0.004, respectively).

CONCLUSIONS

SWAP in its existing condition is markedly less efficient than either SAP or FDT in detecting VF defects, especially in glaucoma patients and ocular hypertensives (defects detected with SWAP are less than both SAP and FDT). Defects detected with FDT are equivalent to SAP and sometimes larger, especially in ocular hypertensives and glaucoma suspects; this makes it a useful tool for picking up early glaucomatous defects in populations at risk.

Visual field defects and neural losses from experimental glaucoma

Glaucoma is a relatively common disease in which the death of retinal ganglion cells causes a progressive loss of sight, often leading to blindness. Typically, the degree of a patient's visual dysfunction is assessed by clinical perimetry, involving subjective measurements of light-sense thresholds across the visual field, but the relationship between visual and neural losses is inexact. Therefore, to better understand of the effects of glaucoma on the visual system, a series of investigations involving psychophysics, electrophysiology, anatomy, and histochemistry were conducted on experimental glaucoma in monkeys. The principal results of the studies showed that, (1) the depth of visual defects with standard clinical perimetry are predicted by a loss of probability summation among retinal detection mechanisms, (2) glaucomatous optic atrophy causes a non-selective reduction of metabolism of neurons in the afferent visual pathway, and (3) objective electrophysiological methods can be as sensitive as standard clinical perimetry in assessing the neural losses from glaucoma. These experimental findings from glaucoma in monkeys provide fundamental data that should be applicable to improving methods for assessing glaucomatous optic neuropathy in patients.

Glaucomatous damage patterns by short-wavelength automated perimetry (SWAP) in glaucoma suspects

PURPOSE

To determine the glaucomatous visual field damage patterns by short-wavelength automated perimetry (SWAP) in glaucoma suspects, and to compare the frequency of diffuse visual field losses and localized defects.

METHODS

157 eyes of 157 ocular hypertensive subjects who met the selection criteria (intraocular pressure greater than 21 mm Hg and normal standard visual fields) were studied. SWAP was done with a modified Humphrey Field Analyzer. Total (TD) and Pattern Deviation (PD) probability maps were calculated for SWAP. The frequency of abnormlities in the TD and PD were determined, analyzing the visual field loss components.

RESULTS

The involvement of the test points was more frequent on the TD plots than on the PD plots for all levels of defects (p< 0.001). The glaucomatous defects also showed certain topographical distribution.

CONCLUSIONS

A diffuse sensitivity component of visual field loss was found at all SWAP defect depths in glaucoma suspects.

Short wavelength automated perimetry

Short Wavelength Automated Perimetry (SWAP) utilizes a blue stimulus to preferentially stimulate the blue cones and a high luminance yellow background to adapt the green and red cones and to saturate, simultaneously, the activity of the rods. This review describes the theoretical aspects of SWAP, highlights current limitations associated with the technique and discusses potential clinical applications. Compared to white-on-white (W-W) perimetry, SWAP is limited clinically by: greater variability associated with the estimation of threshold, ocular media absorption, increased examination duration and an additional learning effect. Comparative studies of SWAP and W-W perimetry have generally been undertaken on small cohorts of patients. The conclusions are frequently unconvincing due to limitations for SWAP in the delineation of abnormality and of progressive field loss. SWAP is almost certainly able to identify glaucomatous visual field loss in advance of that by W-W perimetry although the incidence of progressive field loss is similar between the two techniques. Increasing evidence suggests that functional abnormality with SWAP is preceded by structural abnormality of the optic nerve head and/or the retinal nerve fibre layer. SWAP appears to be beneficial in the detection of diabetic macular oedema and possibly in some neuro-ophthalmic disorders.

Short wavelength automated perimetry in age related maculopathy

BACKGROUND/AIMS

Previous studies reported the predictive value of the short wavelength sensitive (SWS) cone mediated sensitivity for visual outcome in age related macular degeneration. In this study SWS sensitivity was measured by commercially available blue on yellow perimetry in patients with non-exudative age related maculopathy (ARM) and compared with the presence of morphological risk factors and the status of the fellow eye.

METHODS

In a prospective cross sectional study, 126 patients (57 males, 69 females, mean age 71 (SD 6) years) with ARM (visual acuity >20/50) were tested. Central visual fields (blue on yellow) were obtained with a conventional perimeter. Fundus slides were graded by two independent observers for soft drusen and presence of focal hyperpigmentation.

RESULTS

Mean sensitivity and standard deviation of all patients exhibited a significant reduction with age. Patients with soft drusen had significantly lower sensitivity than those without, whereas there were no differences in visual acuity (log MAR). Sensitivity was also reduced in those eyes with fellow eyes having a sight threatening complication of age related macular degeneration (AMD). Eyes with focal hyperpigmentation compared with those without had no loss of sensitivity, but did have a significant decrease in the central part of the field compared with the more eccentric.

CONCLUSION

SWS sensitivity loss is associated with common risk factors for progression to AMD. Short wavelength automated perimetry is moderately rapid and readily available. It may serve as a tool in future ARM trials.

Relationship between visual field testing and scanning laser polarimetry in patients with a large cup-to-disk ratio

PURPOSE

To determine the relationship between quantitative nerve fiber layer measurements and visual field testing in patients with large cup-to-disk ratios.

METHODS

Seventy-six patients with vertical cup-to-disk ratios by contour of at least 0.8 on stereoscopic photographs and 50 normal subjects were included. One eye was randomly selected for study. All patients underwent standard achromatic automated perimetry, short-wavelength automated perimetry, and retinal nerve fiber layer measurements with scanning laser polarimetry. Analysis of variance was used to evaluate differences between the subject groups. Significance of pairwise comparisons was determined using the Tukey-Kramer multiple comparison test.

RESULTS

Statistically significant differences in nerve fiber layer measurements between patients with large cup-to-disk ratios and both abnormal standard achromatic automated perimetry and short-wavelength automated perimetry (n = 22) and patients with large cup-to-disk ratios and both normal standard achromatic automated perimetry and short-wavelength automated perimetry (n = 42) were found for superior nasal ratio, maximum modulation, ellipse modulation, and the linear discriminant function (Tukey-Kramer less than.05). There was no significant difference in patients with abnormal short-wavelength automated perimetry only (n = 9) as compared with patients with both normal standard achromatic automated perimetry and short-wavelength automated perimetry and patients with both abnormal standard achromatic automated perimetry and short-wavelength automated perimetry. Statistically significant differences between the normal subjects and patients with large cup-to-disk ratios and both abnormal standard achromatic automated perimetry and short-wavelength automated perimetry were found for all retinal nerve fiber layer parameters, with the exception of symmetry, superior ratio, and inferior ratio.

CONCLUSION

Our results show considerable overlap in nerve fiber layer measurements in eyes with large cup-to-disk ratio and abnormal visual fields as compared with eyes with large cup-to-disk ratios and normal visual fields. This may limit the clinical usefulness of scanning laser polarimetry for detection of early glaucoma in patients with large cup-to-disk ratios. Longitudinal studies are needed to determine if patients with large cup-to-disk ratios with normal standard achromatic automated perimetry and abnormal short-wavelength automated perimetry subsequently develop standard achromatic automated perimetry defects and if scanning laser polarimetry can concurrently detect progression of nerve fiber layer damage.

Effect of cataract extraction on blue-on-yellow visual field

PURPOSE

It is assumed that cataract can influence the results of blue-on-yellow perimetry. However, actual sensitivity change in blue-on-yellow perimetry before and after cataract surgery has not been fully demonstrated.

METHODS

Prospective.

SETTING

Institutional.

STUDY POPULATION

Twenty-two eyes of 22 consecutive patients without ocular pathology, other than cataract, known to influence visual field undergoing cataract surgery.

OBSERVATION PROCEDURES

Both white-on-white (W-W) and blue-on-yellow (B-Y) perimetries.

MAIN OUTCOME MEASURES

Global indexes including mean deviation and other pertinent data of white-on-white and blue-on-yellow perimetries were compared before and after cataract surgery.

RESULTS

Mean deviation was improved after cataract surgery in both white-on-white perimetry (from -6.88 dB to -3.36 dB, P <.0001) and blue-on-yellow perimetry (from -12.22 dB to -3.64 dB, P <.0001, paired t test). However, the mean difference between preoperative and postoperative mean deviation in blue-on-yellow perimetry (8.58 +/- 3.96 dB) was significantly higher than that of white-on-white perimetry (3.52 +/- 2.69 dB; P <.0001, unpaired t test). That is, the change in mean deviation was greater in blue-on-yellow perimetry than in white-on-white perimetry by a factor of 2.4 times.

CONCLUSION

Cataract causes predominantly a general reduction of sensitivity in both blue-on-yellow and white-on-white perimetries, and the general reduction of blue-on-yellow sensitivity is far greater than that of white-on-white sensitivity.

Blue-on-yellow perimetry with a scanning laser ophthalmoscope: small alterations in the central macula with aging

The sensitivity of short-wavelength-sensitive (SWS) cone pathways was measured in the central fields of 74 normal subjects, aged 17-86 yr, with healthy maculas. The new fundus perimetry technique used a research scanning laser ophthalmoscope with a small entrance pupil to present blue static perimetry targets on a bright yellow background. Simultaneous infrared imaging aided target positioning and rapid assessment of potential pathology in elderly subjects. Targets were positioned peripheral to fixation, avoiding both the SWS-cone-free area and the peak macular pigment, determined in 11 subjects. Sensitivity declined 0.019 log unit per decade, while intraindividual variability across loci increased. The nasal-temporal asymmetry remained constant. Sensitivity of older subjects was relatively less for the most central targets but was unrelated to transmission through macular pigment. Retinal changes with age occur to differing extents or at differing rates and are readily detectable in the central macula.

Incidence and prevalence of short wavelength automated perimetry deficits in ocular hypertensive patients

PURPOSE

To determine the prevalence and incidence of short wavelength automated perimetry deficits in comparison to standard automated perimetry deficits in patients with ocular hypertension.

METHODS

Five hundred eyes of 250 patients with ocular hypertension were recruited into a prospective, longitudinal study and tested with standard automated perimetry and short wavelength automated perimetry annually for 5 years. Both eyes of 60 normal subjects, 21 to 85 years of age, were used to establish normative data for short wavelength automated perimetry and standard automated perimetry. This allowed independent evaluation of left and right eyes of patients. All normal data were corrected for age, and short wavelength automated perimetry results were corrected for lens transmission. The lowest fifth and first percentiles for the normal observers were derived for the 10 glaucoma hemifield test zones for short wavelength automated perimetry and standard automated perimetry. Visual fields were considered outside normal limits if two glaucoma hemifield test zones were below the normal fifth percentile or one glaucoma hemifield test zone was below the normal first percentile.

RESULTS

Baseline prevalence of short wavelength automated perimetry and standard automated perimetry deficits were 9.4% and 1.4%, respectively. During the study, incident rates of field loss were 6.2% (1.23% per year) for short wavelength automated perimetry and 5.9% (1.18% per year) for standard automated perimetry. Once abnormal, 80% of short wavelength automated perimetry fields remained abnormal on the next examination, whereas only 45% of abnormal standard automated perimetry fields remained abnormal. New short wavelength automated perimetry deficits in ocular hypertensives were more prominent and more persistent than new standard automated perimetry deficits.

CONCLUSIONS

Our findings are consistent with the interpretation that short wavelength automated perimetry deficits occur before standard automated perimetry deficits in glaucoma. The similar incidence rates suggest that both standard automated perimetry and short wavelength automated perimetry are monitoring the same underlying glaucomatous disease process.

What Does Functional Testing Tell Us About Optic Nerve Damage?

Information from different regions of the visual field travels through specific bundles of retinal ganglion cell axons. This visual information is disrupted in patients with glaucoma, and the effects can be seen in measurements of the visual field and optic nerve. Typical shapes and sizes of glaucomatous field defects result from damage to these nerve fiber bundles at the level of the optic disk, and we have identified specific patterns of progression. These patterns apply to the visual function-specific field tests that are designed to indirectly assess sub-populations of retinal ganglion cells. The rationale for these tests is described. An argument for the importance of using visual function techniques to assess progression in an individual patient is given.

Psychophysical Measurement of Glaucomatous Damage

Within the past twenty years, a number of new psychophysical test procedures have been adapted for use in perimetry and visual field testing. These procedures are designed to measure the functional properties of different types of retinal ganglion cell subpopulations. Although many of these new procedures exhibit better performance characteristics than standard automated perimetry, no single test procedure appears to be decidedly superior to all others. Comparison of multiple functions in patients with early glaucomatous damage suggests that visual function losses are not selective for specific retinal ganglion cell subpopulations in all patients. For evaluation of the efficacy of neuroprotective agents in glaucoma, one of the challenges facing the development of new psychophysical tests is to be able to distinguish visual function losses that are due to ganglion cell drop-out ("dead" cells) from those that are due to malfunctioning retinal nerve fibers ("sick" cells).

Chromatic and achromatic defects in patients with progressing glaucoma

To evaluate the pattern of losses associated with glaucomatous injury in patients with progressing glaucoma, functional losses were examined in 14 patients with progressing glaucoma using tests for which detection should be selectively mediated by one of three psychophysical mechanisms. Red-on-white increments, blue-on-white increments and critical flicker frequency were used to isolate the responses of the red-green chromatic mechanism, the blue-on chromatic mechanism, and the high-frequency flicker achromatic mechanism. For our 3.1 degrees circular stimuli, chromatic defects were found in a greater number of the patients with glaucoma than were achromatic defects. We evaluated these defects in terms of two existing hypotheses: preferential loss and reduced redundancy. The greater sensitivity to glaucomatous injury of chromatic tests, compared to achromatic tests, found in this and other studies and the apparent discrepancy between anatomical and psychophysical studies can be parsimoniously explained by differences in cortical summation of ganglion cell responses for the chromatic and achromatic pathways.

Functional and structural measurements in a multifactorial glaucoma risk model

PURPOSE

To evaluate the relationship between a multifactorial probability risk model of developing glaucomatous visual field defects and the assessment of the retinal nerve fiber layer (RNFL) and short-wavelength automated perimetry (SWAP) in glaucoma suspects.

METHODS

157 eyes of 157 glaucoma suspects were included in the study. The risk of developing glaucomatous defects was assessed by applying a multifactorial model that included intraocular pressure, vertical cup-to-disk ratio, age and family history. Photographs of the RNFL and SWAP were performed.

RESULTS

The SWAP was abnormal in 54 cases (34.3%); 21% of abnormal perimetries were obtained in the low-risk group, 37% in the moderate risk group and 56% in the high risk group. The nerve fiber layer evaluation in the different risk stages showed a pattern similar to the results obtained with SWAP. Multiple regression analyses, performed with the four variables included in the model with SWAP and RNFL evaluation, showed the relationship between the risk factors and the presence of glaucomatous damage--evaluated by RNFL and SWAP (p<0001).

CONCLUSIONS

The probability model showed a good correlation between the risk scale and the RNFL and SWAP assessment.

Nerve fiber analyzer and short-wavelength automated perimetry in glaucoma suspects: a pilot study

PURPOSE

To test the relationship between the results of short-wavelength automatic perimetry (SWAP) and retinal nerve fiber layer (RNFL) measurements with scanning laser polarimetry (Nerve Fiber Analyzer, NFA) in age-matched normal subjects, glaucoma suspects, and early glaucoma patients.

DESIGN

Case-control study.

PARTICIPANTS AND METHODS

Thirty-eight normal subjects, 32 glaucoma suspects, and 14 early glaucoma patients were recruited. All subjects underwent RNFL assessment by NFA, achromatic visual field testing (24-2 threshold), and repeated SWAP (24-2 threshold blue-on-yellow).

MAIN OUTCOME MEASURES

Mean deviation (MD) of visual field testing and RNFL values were obtained.

RESULTS

Glaucoma suspects were divided into two groups according to their SWAP results: high risk (with SWAP abnormalities) and low risk (with normal SWAP result). No statistically significant difference in SWAP MD and RNFL values were observed between normal and low-risk groups (P > 0.05), but these values were found to be significantly lower in high-risk and early glaucoma groups (P < 0.01).

CONCLUSIONS

This study suggests that RNFL examination by NFA may be a useful test for the early detection of glaucomatous damage of glaucoma suspects. It appears to provide agreement with SWAP abnormalities and is more sensitive than conventional standard automated perimetry.

New perimetric threshold test algorithm with dynamic strategy and tendency oriented perimetry (TOP) in glaucomatous eyes

PURPOSE

To investigate the time-wise reliability and efficiency of two new perimetric test algorithms, two computerised static threshold perimetry strategies, namely dynamic strategy (DS) and tendency oriented perimetry (TOP), were compared with the standard full-threshold strategy (normal strategy, NS).

METHODS

We examined 41 eyes of 41 normal individuals without any ocular disease and 36 eyes of 36 glaucomatous patients, with the NS (4-to-2 dB), DS and TOP using an Octopus 1-2-3 perimeter. We analysed test time, stimulus time and the two global indices, mean sensitivity (MS) and loss variance (LV). Program 32X was used as test grid pattern.

RESULTS

The mean test time for the NS was reduced by 52% with the DS and by 78% with the TOP strategy. Concerning the global indices, the MS value did not differ among the three strategies in the control or glaucoma group. However, the LV value was lower in the TOP strategy compared with the other two strategies in the glaucoma group. This suggested that the TOP strategy underestimated local glaucomatous visual field defects. The ability to detect early-stage glaucoma with the DS and TOP was inferior to that with the NS.

CONCLUSIONS

The DS was more efficient than the TOP strategy for the detection of early glaucomatous defects, whereas the TOP strategy required less testing time. The TOP strategy may be an appropriate approach for patients in whom time-consuming perimetry is not possible, or in whom the visual field defect is already advanced.

Visual field progression in patients with initially unilateral visual field loss from chronic open-angle glaucoma

PURPOSE

To investigate visual field progression in patients with initially unilateral glaucomatous visual field loss, and to determine risk factors for progression.

DESIGN

Retrospective observational case series.

PARTICIPANTS

Forty-eight consecutive patients with primary open-angle glaucoma, pseudoexfoliative glaucoma, or pigmentary glaucoma, seen over an 18-month period, who initially had unilateral visual field loss as defined by use of modified Anderson criteria. Patients were followed with standard Humphrey perimetry for a minimum of 2 years.

METHODS

Progression was defined by use of modified Anderson criteria, and Advanced Glaucoma Intervention Study (AGIS) and Collaborative Initial Glaucoma Treatment Study scores.

MAIN OUTCOME MEASURE

Visual field progression.

RESULTS

Three patients (6.2%) had fellow eye progression over a mean follow-up of 76 months and duration of disease of 8.7 years. Fellow eye progression correlated with progression of the first-affected eye (P = 0.044). Ten patients (21%) had progression of the first-affected eye; these eyes had a larger initial cup/disc ratio compared with stable eyes (P = 0.041). Increasing initial AGIS score was associated with progression (P: = 0.003). Kaplan-Meier survival analysis estimated the risk of progression at 5 years to be 25% in first-affected eyes and 7.2% in fellow eyes.

CONCLUSIONS

In this population, the risk of fellow eye progression in patients with initially unilateral visual field loss from open-angle glaucoma is low. Progression is higher in eyes with visual field loss at initial testing, and the risk of progression increases as the level of initial visual field loss increases.

A comparison of short wavelength automated perimetry with frequency doubling perimetry for the early detection of visual field loss in ocular hypertension

BACKGROUND

Achromatic automated perimetry (AAP) is limited in its ability to detect very early visual field loss in ocular hypertensive patients. Tests targeting axons that are selectively damaged, or have low redundancy, may detect visual field losses before they are seen on AAP. It has been claimed that short wavelength automated perimetry (SWAP) and frequency doubling perimetry (FDP) are two tests that provide early detection.

METHODS

Patients (n = 62) were selected on the basis that they had raised intraocular pressure but normal visual fields detected by AAP. A SWAP and an FDP was performed on each of the patients and the results compared. Fields were scored as either normal or abnormal based on criteria used in previous studies.

RESULTS

On comparing FDP with SWAP as the 'gold standard', a sensitivity of 88.9% and a specificity of 96.2% was found, showing a high concordance between the two tests.

CONCLUSION

These results suggest that as SWAP may be predictive of AAP visual field loss, FDP may be similarly predictive.

Short-wavelength automated perimetry: it's role in the clinic and for understanding ganglion cell function

Short-wavelength automated perimetry (SWAP) is a more sensitive test than standard achromatic perimetry for early loss of vision due to glaucoma and other ocular and neurological diseases. SWAP is also more successful for detecting changes in vision as glaucoma progresses. Results from various visual function-specific tests, including SWAP, suggest that there are individual differences in ocular hypertensive and glaucoma eyes in the subtype of ganglion cell first affected. However, the disease targets the same retinal area for all function-specific tests that show a deficit in a given individual. Psychophysical tests of vision are critical to understand glaucoma's effect on retinal ganglion cells, to verify the success or failure of treatment including new neuroprotective agents, and to determine the relationship of genetic markers for glaucoma to the presence and progress of the disease.

Visual fields in glaucoma: a clinical overview

Static automated visual field testing is now an integral part of the detection and monitoring of primary open angle glaucoma. However, although many aspects of testing are automated, interpretation of the large amounts of data produced by these instruments is not. Two major challenges facing the practitioner are differentiating between the visual fields of a patient with early glaucoma and those of a normal patient, and identifying whether small reductions in sensitivity are due to a true defect or a product of other factors. This paper presents a clinical overview of how to systematically review visual field plots and how to recognise defects arising from patient factors, as well as some of the alternative testing techniques available for the assessment of the glaucoma patient.

Relationship between structural abnormalities and short-wavelength perimetric defects in eyes at risk of glaucoma

PURPOSE

To determine the relative prevalence of blue-yellow perimetric defects and structural abnormalities of the optic nerve and nerve fiber layer in eyes at risk of glaucoma.

METHODS

Seventy-two eyes (of 72 patients) at risk of glaucoma, with normal white-on-white full threshold perimetry, were examined prospectively with blue-yellow full-threshold perimetry (Humphrey). Structural evaluations were conducted with qualitative assessment of stereoscopic color optic disk photographs and monochromatic nerve fiber layer photographs performed independently by three masked examiners (a glaucoma specialist and two glaucoma fellows), and statistical analysis of summary parameters was obtained with scanning confocal laser tomography (abnormal defined as values outside 95% confidence limits established in normal control subjects).

RESULTS

Kappa values for interobserver agreement were 0.64, 0.88, and 0.79 for optic disk evaluation and 0.59, 0.60, and 0.61 for nerve fiber layer evaluation. Thirteen (18%) of 72 eyes had blue-yellow abnormalities. A total of 30 eyes (42%) were identified as having a structural abnormality; 29 (40%) had qualitatively determined optic disk abnormalities, 21 (29%) had qualitatively determined nerve fiber layer defects, and 26 (36%) had statistically significant structural abnormalities. Twelve of 13 eyes with blue-yellow defects had a detectable structural abnormality; all 12 had abnormalities identified with disk photography, nine with nerve fiber layer photography, and 12 by scanning laser tomography.

CONCLUSIONS

Clinically detectable structural abnormalities frequently coexist with blue-yellow perimetric defects in patients with ocular hypertension. A substantial proportion of patients with ocular hypertension with normal blue-yellow perimetry has early detectable glaucomatous structural abnormalities.

Comparison of long-term variability for standard and short-wavelength automated perimetry in stable glaucoma patients

PURPOSE

To quantify and compare, on a point-by-point basis, the long-term variability of standard and short-wavelength automated perimetry in a group of stable glaucoma patients.

METHODS

From a group of 53 glaucoma patients experienced in visual field testing, we identified one eye, randomly chosen, from each of 25 glaucoma patients whose condition was found to be stable, based on both standard and short-wavelength automated perimetry visual field criteria. On each of three visits during a period of up to 3 months, each patient performed one standard and one short-wavelength automated perimetry 24-2 visual field in a random order on a Humphrey visual field analyzer. The long-term variability (also referred to as test-retest variability) was defined as the SD of the three threshold decibel values at each test location. The long-term variability for each test point (mean +/- SD) was determined separately for both standard visual fields and short-wavelength automated perimetry.

RESULTS

With all 52 test locations of the 24-2 field averaged, the global long-term variability, mean (+/- SD) for standard visual fields and short-wavelength automated perimetry was 2.37 +/- 2.03 dB (95% confidence interval, 2.26-2.48 dB) and 2.92 +/- 2.03 dB (95% confidence interval, 2.81-3.03 dB), respectively (P <.0001). In 16 of the 52 visual field locations, long-term variability on short-wavelength automated perimetry was significantly higher than long-term variability on standard visual fields. In addition, the long-term variability increased with greater distance from the point of fixation for both standard visual fields and short-wavelength automated perimetry. The long-term variability decreased closer to fixation, more for standard visual fields than for short-wavelength automated perimetry.

CONCLUSIONS

In a group of stable glaucoma patients, mean long-term variability was 0.55 dB higher for short-wavelength automated perimetry than for standard visual fields. This needs to be taken into consideration when serial visual fields are evaluated for change.

Chromatic contrast sensitivity: the role of absolute threshold and gain constant in differences between the fovea and the periphery

A model of foveal achromatic and chromatic sensitivity [Vision Res. 36, 1597 (1996)] was extended to the peripheral visual field. Threshold-versus-illuminance functions were analyzed to determine effects of eccentricity on absolute thresholds and gain constants of chromatic and luminance mechanisms. The resulting peripheral model successfully predicted peripheral contrast sensitivity as a function of wavelength, for both white and 500-nm backgrounds. We conclude that the short-wavelength-sensitive cone opponent mechanism may mediate thresholds in Sloan's notch in the normal periphery and that interpretation of reduced chromatic sensitivity in the periphery requires an explicit model of how eccentricity affects both the gain constant and the absolute threshold.

Quantitative morphologic and functional evaluation of the optic nerve head in chronic open-angle glaucoma

Glaucoma leads to morphologic changes of the optic nerve head and to functional defects. Morphologic changes in the three-dimensional surface structure of the optic nerve head at its entrance site into the globe can be examined by laser scanning tomography. The standard technique for evaluating functional defects in glaucoma is static computerized perimetry. We compared these two techniques to determine which is more sensitive for follow-up of glaucomatous damage of the optic nerve head. If decreased function is presumed to precede imminent cell death, visual field analysis should be the more sensitive method, as cell death results in absolute defects of the visual field. However, the neuronal networks do not necessarily function in this way. In the case of loss of individual elements in the neuronal network, the complex linkages, even at the retinal level, are able to maintain functions and compensate for loss of function, which means that visual field defects would not be prominent. If the damage increases with time and is accompanied by a progressive loss of ganglion cells, however, compensation is eventually no longer possible, and the functional defects then become measurable by visual field analysis. Thus, morphologic absolute changes may be more prominent than visual field defects in the early stages of glaucoma. To evaluate the quantitative relationship between morphometrically measurable defects of the optic nerve head and measurable functional defects, we first examined the visual field with static computerized perimetry and then evaluated the surface structure with a laser scanning tomograph in 90 patients with chronic open-angle glaucoma, 10 patients with ocular hypertension, and 10 patients without any eye disease. Based on the 95th percentile of the standardized rim/disk area ratio, we calculated the relative rim area loss and correlated this with the mean defect in visual field analysis. The scatterplot shows an exponential curve. In the early stages of glaucoma, visual field defects were less prominent than morphologic absolute changes; 40% of the neuroretinal rim area is lost by glaucomatous optic nerve damage before first defects in visual field analysis appear. In late stages of glaucoma, changes in perimetry are more prominent than those observed with biomorphometry. These results show that in the follow-up of patients with early stages of glaucomatous damage, special attention should be given to morphologic absolute changes. In patients with advanced glaucoma, progress of the damage should be observed by repeated functional, rather than morphologic, examinations. It is important to keep in mind, however, that the sensitivity of any method is dependent on technology. One reason why functional tests may not be as sensitive as morphologic examination in observing patients with early stages of glaucoma may simply be that functional tests are not yet sensitive enough to detect early damage.

Symptomatic and asymptomatic visual loss in patients taking vigabatrin

PURPOSE

To investigate the clinical, perimetric, and electrophysiologic findings in patients with visual field loss on long-term treatment with the antiepileptic medication vigabatrin.

DESIGN

Consecutive observational case series.

PARTICIPANTS

Forty-one consecutive subjects taking vigabatrin referred for screening ophthalmologic assessment were studied. Twelve subjects with evidence of peripheral visual field constriction are presented.

METHODS

Twelve subjects with evidence of peripheral visual field constriction on 60-4 perimetry underwent central 30-2 and blue-on-yellow (B/Y) perimetry, as well as electroretinography (ERG), electro-oculography (EOG), and visual-evoked potential (VEP) testing.

MAIN OUTCOME MEASURES

Visual acuity; fundus abnormalities; visual field loss; and ERG, EOG, or VEP abnormalities were the main outcome measures.

RESULTS

Eight of the 12 subjects with constricted visual fields were asymptomatic. The central 30-2 perimetry demonstrated bilateral visual field constriction in 9 of 12 patients and the B/Y perimetry in 8 of 9 patients tested. Of the ten patients tested electrophysiologically, four had abnormal ERGs, five had abnormal EOGs, and three had delayed VEPs.

CONCLUSIONS

The incidence of visual field constriction in patients taking vigabatrin may be higher, and asymptomatic visual field loss more common, than reported previously. The authors postulate a possible Muller cell dysfunction in the peripheral retina. Patients taking vigabatrin should have regular peripheral visual field examinations.

Relationship between parapapillary atrophy and visual field abnormality in primary open-angle glaucoma

PURPOSE

To investigate the relationship of parapapillary atrophy measured by confocal scanning laser ophthalmoscopy to visual field sensitivity measured with standard automated perimetry and short-wavelength automated perimetry in patients with primary open-angle glaucoma.

METHODS

Forty-seven eyes of 47 primary open-angle glaucoma patients with increased intraocular pressure (> or = 22 mm Hg) were enrolled. Optic nerve head topography and parapapillary atrophy (beta and alpha zones) were assessed by confocal scanning laser ophthalmoscopy. Mean deviation and corrected pattern SD were assessed with standard automated perimetry and short-wavelength automated perimetry.

RESULTS

Beta and alpha zones were found in 23 (49%) and 47 (100%) eyes with primary open-angle glaucoma, respectively. The area of beta zone showed significant correlations with MD of standard automated perimetry, corrected pattern SD of standard automated perimetry, and corrected pattern SD of short-wavelength automated perimetry (Spearman r = -0.366, P = .012; r = 0.327, P = .025; and r = 0.436, P = .002, respectively). The area of alpha zone showed a significant correlation with mean deviation of standard automated perimetry (r = -0.378, P = .009). Mean MD of standard automated perimetry, mean corrected pattern SD of standard automated perimetry, and mean corrected pattern SD of short-wavelength automated perimetry were significantly worse in eyes with beta zone than in eyes without beta zone.

CONCLUSIONS

Parapapillary atrophy measured by confocal scanning laser ophthalmoscopy, especially beta zone, is associated with glaucomatous visual field loss demonstrated by standard automated perimetry and short-wavelength automated perimetry.

Temporal contrast sensitivity with peripheral and central stimulation in glaucoma diagnosis

AIMS

To evaluate temporal contrast sensitivity with full field, peripheral, and central stimulation and to determine the most sensitive corresponding retinal area for glaucoma damage.

METHODS

Temporal contrast sensitivity was determined either with a full field, a peripheral annular area from 30 degrees to 90 degrees, or a central area from 0 degree to 30 degrees at a frequency of 37.1 Hz. 232 eyes of 232 subjects were included. They were classified into four groups: eyes with ocular hypertension (OHT, n = 54), "preperimetric" glaucomas (n = 73) with glaucomatous optic disc abnormalities but no visual field loss, "perimetric" glaucomas (n = 53) with visual field loss, and 52 normals.

RESULTS

In all four groups, temporal contrast sensitivity was almost equal with full field and peripheral, but significantly higher than with central stimulation (p < 0.001). With regard to the diagnostic power of the three different stimulus areas, OHTs and glaucomas were found to be best discriminated from normals by peripheral stimulation.

CONCLUSIONS

According to these results, temporal contrast sensitivity seems to be determined by peripheral retinal areas. As the diagnostic power of the three different stimulus areas was best with the peripheral stimulation, this condition should be used for early glaucoma diagnosis.

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.

Psychophysical Endpoints

While developing neuroprotective agents for managing glaucoma, researchers must be able to demonstrate treatment efficacy by relying on outcome measures other than intraocular pressure (IOP) and endpoints other than lowering of IOP. Attempts to improve the ability to monitor progressive glaucomatous loss have concentrated on new visual field analysis procedures; new, more sensitive test procedures; and the development of methods to reduce variability. Although none of these approaches has achieved a completely satisfactory solution, this article reviews the advantages and disadvantages of currently available techniques in visual field analysis, new perimetric tests, and current methods of reducing variability.

Blue-on-yellow visual field and retinal nerve fiber layer in ocular hypertension and glaucoma

BACKGROUND AND OBJECTIVE

It has been suggested that the clinically detectable changes of the blue-on-yellow (B/Y) visual field and retinal nerve fiber layer (RNFL) may precede standard white-on-white (W/W) visual field defects in the progression of glaucoma. The aim of this study was to test the relationship between the results of B/Y visual fields and semiquantitative RNFL evaluation in corresponding areas and to determine how the B/Y visual fields and RNFL scores label the normal W/W perimetry hemifields in patients with glaucoma and ocular hypertension.

DESIGN

A cohort study.

PARTICIPANTS AND METHODS

Monochromatic RNFL photographs of 32 normal subjects and 29 patients with ocular hypertension and different stages of glaucoma were assessed in a masked fashion. The B/Y and W/W visual fields (program 30-2) were examined with a Humphrey perimeter. The results of both visual fields were adjusted for the patients' age and lens transmission index measured with a lens fluorometer.

MAIN OUTCOME MEASURE

Mean deviation (MD) of visual field and semiquantitative score of RNFL loss were measured.

RESULTS

The total and hemifield MD values of B/Y and W/W visual field showed a statistically significant correlation with diffuse and overall score of RNFL loss in corresponding areas. The hemifield MD values of B/Y perimetry obtained from "normal" W/W hemifields of patients with early glaucoma were well correlated (r = -0.56) with respective RNFL loss scores found to be abnormal in 84% of hemispheres. The difference between the hemifield MD values of B/Y perimetry obtained from normal W/WAN hemifields of patients with ocular hypertension and patients with early glaucoma was not statistically significant (analysis of variance). The respective B/Y hemifield data of normal subjects were statistically significantly different from the data of patients with ocular hypertension and early glaucoma.

CONCLUSIONS

The hemifield MD values of B/Y perimetry correlate well with semiquantitative scores of RNFL loss obtained from the corresponding hemisphere. The B/Y perimetry as well as RNFL assessment may show glaucomatous defects in a hemifield found to be normal on W/W perimetry. In subjects with ocular hypertension, the functional damage detected by B/Y perimetry may, in some cases, precede RNFL defects on conversion to 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.

Test-retest variability of blue-on-yellow perimetry is greater than white-on-white perimetry in normal subjects

PURPOSE

To compare long-term fluctuation of blue-on-yellow automated perimetry with white-on-white automated perimetry in normal subjects.

METHODS

White-on-white and blue-on-yellow automated perimetry were performed on a Humphrey Visual Field Analyzer and an Octopus perimeter, both modified for blue-on-yellow perimetry. The study sample consisted of 31 eyes of 31 normal subjects for the Humphrey perimeter and 33 eyes of 33 normal subjects for the Octopus perimeter. After one practice session, each subject completed four testing sessions over a period of 2 to 8 weeks, each separated by at least 1 day. Each testing session consisted of both white-on-white and blue-on-yellow perimetry performed on one eye; the order of the tests was alternated for successive sessions. Long-term fluctuation (expressed as statistical variance) was calculated for each test location. Intersubject variability (expressed as statistical variance) across all subjects was determined for each test location.

RESULTS

On the Humphrey perimeter, the long term fluctuation for blue-on-yellow perimetry (4.07 +/- 3.07 dB2) was significantly greater than that for white-on-white perimetry (1.97 +/- 0.99 dB2; P < .001). Long-term fluctuation increased as a function of eccentricity for both blue-on-yellow and white-on-white perimetry. Short-term fluctuation was significantly greater for blue-on-yellow (0.46 +/- 0.25 dB) than that for white-on-white perimetry (0.29 +/- 0.19 dB; P < .02). Finally, the intersubject variability was significantly greater in blue-on-yellow (13.2 +/- 2.8 dB2) than it was in white-on-white perimetry (4.25 +/- 1.13 dB2; P < .001). Similar results were found with the Octopus perimeter.

CONCLUSIONS

Long-term fluctuation and short-term fluctuation of blue-on-yellow perimetry are greater than those of white-on-white perimetry in normal subjects. The increased long-term fluctuation requires appropriate statistical approaches when evaluating serial change of blue-on-yellow perimetry.

Computerized color perimetry in multiple sclerosis

Color visual field analysis has proven highly sensitive for early visual impairments diagnosis in MS, yet it has never attained widespread popularity usually because the procedure is difficult to standardize, the devices are costly, and the test is fatiguing. We propose a computerized procedure running on standard PC, cost effective, clonable, and easy handled. Two hundred and sixty-four colored patches subtending 1 degree angle vision, with selected hues and low saturation levels are sequentially and randomly displayed on gray equiluminous background of the PC screen subtending 24 degrees x 40 degrees angle of vision. The subject is requested to press a switch at the perception of the stimulus. The output provides colored maps with quantitative information. Comparison between normals and a selected population of MS patients with no actual luminance visual field defects, showed high statistical difference.

Localization of the fourth locus (GLC1E) for adult-onset primary open-angle glaucoma to the 10p15-p14 region

One of the major causes of blindness is primary open-angle glaucoma, which affects millions of elderly people worldwide. Genetic studies have so far mapped three loci for the adult-onset form of this condition to the 2cen-q13, 3q21-q24, and 8q23 regions. Herein, we report the localization of a fourth locus, to the 10p15-p14 region, in one large British family with a classical form of normal-tension open-angle glaucoma. Of the 42 meioses genotyped in this pedigree, 39 subjects (16 affected) inherited a haplotype compatible with their prior clinical designation, whereas the remaining 3 were classified as unknown. Although a maximum LOD score of 10.00 at a recombination fraction of straight theta=.00 was obtained with D10S1216, 21 other markers provided significant values, varying between 3.77 and 9.70. When only the affected meioses of this kindred were analyzed, LOD scores remained statistically significant, ranging from 3.16 (D10S527) to 3.57 (D10S506). Two critical recombinational events in the affected subjects positioned this new locus to a region of approximately 21 cM, flanked by D10S1729 and D10S1664. However, an additional recombination in a 59-year-old unaffected female suggests that this locus resides between D10S585 (or D10S1172) and D10S1664, within a genetic distance of 5-11 cM. However, the latter minimum region must be taken cautiously, because the incomplete penetrance has previously been documented for this group of eye conditions. A partial list of genes that positionally are considered as candidates includes NET1, PRKCT, ITIH2, IL2RA, IL15RA, IT1H2, hGATA3, the mRNA for open reading frame KIAA0019, and the gene for D123 protein.

Visual dysfunction in HIV-positive patients without infectious retinopathy

Persons with HIV disease are susceptible to various manifestations of retinal damage, such as infectious retinopathies (e.g., cytomegalovirus [CMV] retinitis and toxoplasmosis) and noninfectious complications (microangiopathic infarctions or cotton-wool spots [CWS]); CWS being quite common in AIDS patients. Until recently, little research focused on noninfectious ocular pathology in HIV disease. These disorders may all affect normal functioning of the visual system while funduscopic examination results appear normal. A review of the psychophysical changes, color and contrast sensitivity, peripheral visual function, electrophysiologic and morphologic changes, the relationship of vision loss and neuropsychological changes, postretinal damage, and imaging capabilities cast important new light on quality of life issues and vision function for all HIV/AIDS patients regardless of CD4 count, other measures of wellness, or treatment protocols. Entopic perimetry, a low-cost psychophysical technique screening test, allows sensitive and specific identification of very peripheral areas of visual field loss. The authors recommend its implementation and use by primary care providers, particularly for early detection of retinal damage when funduscopic examination results may appear normal.

Peripheral colour contrast thresholds in ocular hypertension and glaucoma

PURPOSE

To evaluate a new test for peripheral colour contrast sensitivity as a tool for early diagnosis of glaucoma.

PATIENTS AND METHODS

Peripheral colour contrast sensitivity was measured by a computer and colour monitor system developed by Arden and co-workers. The monitor displays an annulus subtending 25 degrees at the retina. During the test, 45 degrees of the annulus is removed in one of four quadrants. The patient is asked to identify this quadrant, first at suprathreshold levels and then as the colour contrast between the annulus and the background is varied in order to establish the threshold for identification. The tested colours were varied along the protan, deutan and tritan colour confusion axes, respectively. Thirty-three normal subjects, 22 glaucoma patients and 69 ocular hypertensive patients were examined. The ocular hypertensive patients were divided into a low risk group, a medium risk group and a high risk group.

RESULTS

The colour contrast thresholds for the glaucoma group and the high risk ocular hypertensive group were significantly (p < 0.001) higher for all three colour axes compared with the normal group. There were also significant (p < 0.05-0.001) differences for all axes between the glaucoma group on the one hand and the ocular hypertensive low risk group on the other hand. There were, however, overlaps in colour contrast thresholds between all groups.

CONCLUSION

Although there is a large and statistically significant difference in average colour contrast thresholds between normals and glaucoma patients, it was difficult to find an appropriate cut-off point to separate the two groups. Further studies must clarify the influence of early stages of common diseases such as cataract, diabetes and age-related maculopathy on colour contrast sensitivity.

Perimetric motion thresholds are elevated in glaucoma suspects and glaucoma patients

The purpose of this study was to determine if a clinically feasible perimetric motion test utilizing random-dot kinematograms could identify glaucomatous visual field defects. Using a staircase procedure, an automated perimetric motion test and a larger foveally presented target were given to normal (n = 30), glaucoma suspects (n = 31) and primary open-angle glaucoma patients (n = 19). Motion thresholds at specific locations throughout the whole visual field were significantly elevated in glaucoma patients (P < or = 0.001). Perimetric motion testing identified 84.2% of the primary open-angle glaucoma patients and 25.8% of the glaucoma suspects as abnormal. A larger foveal stimulus was unable to distinguish between the different subject groups (P < or = 0.185). Perimetric motion thresholds were significantly correlated with Humphrey standard visual field thresholds in the glaucoma and glaucoma-suspect patients (P < or = 0.0002).

Asymmetries in the normal short-wavelength visual field: implications for short-wavelength automated perimetry

PURPOSE

To quantify short-wavelength sensitivity in normal eyes by hemifield location, eccentricity, and age.

METHODS

We measured achromatic and short-wavelength thresholds across visual fields covering a radius of 21 degrees of visual angle in 115 normal eyes in subjects aged 17 to 77 years and out to 30 degrees of eccentricity in an additional 57 eyes in subjects aged 22 to 80 years.

RESULTS

Results indicated significantly greater sensitivity for the inferior visual field compared with the superior field (P = .001). The amount of asymmetry increased with eccentricity (P = .001) but not with age (P = .357). A temporonasal field asymmetry was noted at the most eccentric points of the 30-degree field (P = .001) but not at 21 degrees (P = .821).

CONCLUSIONS

In addition to increasing our understanding of normal retinal function, these results have implications for basic research in comparison with results of studies using different retinal locations to assess short-wavelength sensitivity and for clinical practice, where short-wavelength sensitivity is used to diagnose and manage a number of diseases, including glaucoma, diabetic retinopathy, and acquired immunodeficiency syndrome (AIDS)-related vision loss.

Mapping structural damage of the optic disk to visual field defect in glaucoma

PURPOSE

To evaluate the relation between the location of focal visual field defects and optic disk damage in eyes with glaucoma by short-wavelength automated perimetery and confocal scanning laser ophthalmoscopy.

METHODS

In 14 patients (14 eyes) with open-angle glaucoma, focal optic disk damage, and focal visual field loss, we obtain visual fields with short-wave-length automated perimetry. The short-wavelength automated perimetry visual field was divided into 21 zones, representing retinal nerve fiber layer arcuate bundles. Test points were compared with a normative database. The optic disk was assessed with a confocal scanning laser ophthalmoscope. Optic disk measurements were calculated in 10-degree sectors and compared with a normative database using a new measure, the rim area ratio, which adjusts for individual differences in disk size.

RESULTS

The mean number (+/-SD) of damaged visual field zones was 3.9 (+/-1.9), and the mean number of damaged rim sectors was 5.0 (+/-2.9). Focal defects on the optic disk and on short-wavelength automated perimetry were topographically related with specific damaged visual field zones corresponding to specific damaged rim sectors.

CONCLUSIONS

In patients with open-angle glaucoma with focal optic disk damage and focal visual field loss, defects in optic disk and short-wavelength automated perimetry are topographically related. The rim area ratio can be used to identify focal optic nerve defects.

Motion coherence perimetry in glaucoma and suspected glaucoma

Motion direction sensitivity in glaucoma patients, glaucoma suspects and controls was assessed perimetrically at 22 visual field locations using small random dot kinematograms and a motion coherence task. For foveal stimulus presentations, mean motion coherence sensitivity was normal in both patient groups. However, nearly all glaucoma patients and about half of glaucoma suspects (all with normal visual fields as assessed with static perimetry) had some deficit of motion sensitivity. These were most pronounced and most prevalent in the superior field at 15 and 21 deg eccentricity. Glaucoma appears to produce a reduction in the normal integrative visual function necessary for the perception of global motion in textured displays and this disruption is non-uniformly distributed across the visual field.

Repeatable diffuse visual field loss in open-angle glaucoma

PURPOSE

The authors determined the frequency of repeatable diffuse loss as the only form of visual field damage in patients with early to moderate open-angle glaucoma in a prospective follow-up study.

METHODS

The study contained 113 patients (median age, 64 years; range, 17-89 years) who were tested at 6-month intervals with program 30-2 of the Humphrey Field Analyzer (Humphrey Instruments Inc., San Leandro, CA). Although the inclusion criterion for visual acuity was > or = 20/40, on entry, 94 (83.2%) patients had an acuity of > or = 20/25. Cumulative defect curves were generated for all visual fields (median per patient, 7; range, 4-9). After randomizing the order and removing all patient information, two observers independently rated each visual field as being "normal" or showing "diffuse," "localized," or "diffuse and localized" loss. We defined repeatable diffuse loss as occurring when at least two thirds of the number of fields in the follow-up were classified as "diffuse."

RESULTS

Fourteen patients (12.4%) had repeatable diffuse loss according to the cumulative defect curves. After reviewing their clinical charts, we excluded six of these patients because of early lens changes despite good visual acuity and three because of a suggestion of localized loss (on pattern deviation probability plots) in addition to the predominantly diffuse loss. The remaining five (4.4%) patients had repeatable diffuse loss that was due solely to open-angle glaucoma.

CONCLUSION

Although diffuse visual field loss is exaggerated by factors other than glaucoma in the majority of patients, it can occur repeatedly in a small number of patients as the only sign of visual field damage.

Motion perception thresholds in areas of glaucomatous visual field loss

This study examined whether one can differentiate between areas of known visual field loss and areas of known relative field sparing in eyes with primary open angle glaucoma using motion coherence thresholds. Two visual field locations from patients with primary open angle glaucoma (n = 14), which differed significantly in sensitivity, were selected for presentation of a motion stimulus. In the area of visual field loss mean threshold was 17.4 +/- 4.1 dB (1.74 +/- 0.41 log units relative to the brightest stimulus). In the area of relative field sparing mean threshold was 27.0 +/- 3.6 dB (2.70 +/- 0.36 log units). Motion coherence thresholds were significantly poorer for the area of visual field loss compared to the area of relative field sparing (P < 0.0032, two-tailed paired t-test). This result suggests that a perimetric type motion test should be evaluated for early detection of glaucoma.