High-pass resolution perimetry

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°to 90°, or a central area from 0°to 30°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 senstitivity 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 diVerent 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 diVerent stimulus areas was best with the peripheral stimulation, this condition should be used for early glaucoma diagnosis. (Br J Ophthalmol 1999;83:199-205)

Section: Discussionmentioning

confidence: 99%

Temporal contrast sensitivity with peripheral and central stimulation in glaucoma diagnosis

Velten

Korth

Horn

et al. 1999

“…Although a number of studies have selectively tested either magnocellular or parvocellular pathways in early glaucoma, [4][5][6][7][8][9][10][11][12] selective damage to the magnocellular pathway has not been a robust and consistent finding. [13][14][15] When magnocellular (M) and parvocellular (P) functions are assessed using a battery of tests a selective deficit in magnocellular function does not appear to be a consistent feature of early glaucoma.…”

mentioning

confidence: 99%

Psychophysical characterisation of early functional loss in glaucoma and ocular hypertension

Ansari

2002

Aim: The psychophysical evaluation of selective cell loss in early glaucoma and ocular hypertension. Methods: Contrast sensitivity was measured for the detection of luminance modulated gratings at a range of spatial (0.5, 2, 8 c/deg) and temporal (0, 16 Hz) frequency combinations in three groups of age matched patients (primary open angle glaucoma, ocular hypertension, normal controls; n=16). Stimuli of 5°were presented foveally and at 15°along the nasal horizontal meridian under photopic conditions. Results: Fovea: Compared to the normal group, the thresholds for the glaucoma patients were significantly elevated at all spatial and temporal frequencies (p<0.0001), but this reduction was not significantly different at any particular spatial or temporal frequency (p>0.1). There was no difference in contrast sensitivity between the normals and OHTs (p>0.10). Periphery: The thresholds of the glaucoma patients were elevated compared to the normal controls (p<0.01). The loss of sensitivity was slightly greater at the higher spatial frequencies for both stationary and flickering patterns but this did not reach significance (p=0.09). The contrast sensitivity in normal and OHT groups was not significantly different (p>0.10). Conclusions: In early glaucoma, the reduction in contrast sensitivity to stimuli which isolate the magnocellular pathway (0.5 c/deg, 16 Hz) was not significantly different compared with the reduction in contrast sensitivity to stimuli that isolate the parvocellular pathway. These findings are not consistent with the hypothesis that the magnocellular pathway is selectively damaged in early glaucoma.H istological studies in the early stages of both human and experimental glaucoma have shown a selective reduction in the proportion of larger retinal ganglion cells. 1-3Since magnocellular cells tend to be larger at every eccentricity, it is reasonable to conclude that this would translate into a selective loss of magnocellular function. The important clinical implication is that the selective evaluation of magnocellular function should facilitate the earlier detection of ganglion cell loss in glaucoma, possibly before the development of field defects as detected by available clinical perimetric tests.Although a number of studies have selectively tested either magnocellular or parvocellular pathways in early glaucoma, 4-12 selective damage to the magnocellular pathway has not been a robust and consistent finding.13-15 When magnocellular (M) and parvocellular (P) functions are assessed using a battery of tests a selective deficit in magnocellular function does not appear to be a consistent feature of early glaucoma. 16The discrepancy between the anatomical data and psychophysical data questions the anatomical basis for selective cell death. A key point in extrapolating changes in cell size distributions to changes in the proportions of particular classes of cells has been the assumption that the normal relation between cell size and cell type is preserved in disease. Recent anatomical data in the experiment...

“…HRP has been described in full detail previously 6. In brief, HRP uses different-size ring-shaped targets, of constant contrast, displayed on a cathode ray monitor under computer control.…”

Section: Methodsmentioning

confidence: 99%

Influence of ageing on visual field defects due to stable lesions

Rudolph

Frisén²

2007

Background: Knowledge about the effects of ageing on visual field defects is very sparse. Methods: Long-term follow-up records were examined from 28 patients with light-to-moderate visual field defects remaining after surgery for pituitary tumours. All were proven free from tumour recurrences and complicating disorders. Hence, all had isolated, stable lesions of the chiasm. Follow-up periods ranged over 4-18 years (median 9). Using high-pass resolution perimetry, results were analysed from the central-most test locations in the upper temporal and upper nasal quadrants. The former typically bear the brunt of damage whereas the latter are least affected. Each patient contributed results from one eye only. Fixation stability and reproducibility were uniformly good. Results: Measuring values from the nasal quadrants remained essentially constant throughout the follow-up periods. Results from the temporal (T) quadrants were contrasted with those from the nasal (N) quadrants by calculating the T/N ratios, which were then individually regressed over follow-up periods. Hence, each patient was his or her own control. The absolute majority of regression coefficients (25 out of 28) did not significantly differ from 0. Conclusion: The rate of age-related loss of neural channels appears to be identical in normal and abnormal visual field areas in subjects with stable mid-chiasmal lesions.