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British Congress of Optometry and Visual Science
Author(s) -
Anderson Roger,
Little JulieAnne
Publication year - 2016
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/opo.12329
Subject(s) - optometry , vision science , computer science , medicine , artificial intelligence
Purpose: To compare variability characteristics of four different stimuli for measuring changes inspatial summation clinically in patients with glaucoma.Methods: Psychometric functions were measured using the method of constant stimuli for fourstimulus forms in 19 patients with glaucoma (median age, IQR: 69.4, 66.7–72.6 years; median MD,IQR: -5.7, -8.5–-2.8dB), and 10 age-similar healthy controls (median age, IQR: 66.3, 62.3–72.1 years;median MD, IQR: +0.4, -0.4-+1.0dB). Achromatic stimuli were presented at 4 diagonal visual fieldlocations (9.9° eccentricity) on an OLED display (background: 10cd/m2). Stimuli were: (i) fixedcontrast (0.5, suprathreshold at Ricco’s area) varying in area; (ii) fixed area, within Ricco’s area(0.02deg2), varying in contrast; (iii) area and contrast varying simultaneously, and (iv) fixed area,equivalent to Goldmann III (0.15deg2), varying in contrast (control). Energy increments and visibilitywere equated across stimulus forms. Threshold (50% seen) and response variability (slope), werederived from each function. Dependence of response variability on the severity of visual fielddamage was investigated with linear regression.Results: Response variability increased with severity of damage for all stimulus forms. The smallestincrease was found for stimulus (i) (regression line slope: 0.17, p=0.07). The increase in variabilitywas statistically significant for all other stimuli (mean slope 0.2, all pu003c0.01).Conclusions: Stimuli of fixed contrast (suprathreshold at Ricco’s area) varying in area offers lowestdependence of response variability on disease severity. This may offer advantages for more accurateidentification of true changes in visual field damage, particularly in moderate-advanced disease.