Differentiation Between Glaucomatous Scotoma Progression in Depth and in Size by Using Scotoma–Oriented Perimetry (SCOPE) With Locally Condensed Stimulus Arrangements

Abstract

Abstract: : Purpose: To differentiate between two modalities of progression in glaucomatous visual field loss, i.e. deterioration in defect depth vs. increase in defect size. Methods: 69 eyes of 69 glaucoma subjects at risk of progression (33 females, 36 males; age from 13 to 75 yrs.) were examined with automated static perimetry (4–2–1 dB strategy with at least 3 reversals) in a minimum of four subsequent sessions on the Tuebingen Computer Campimeter or the Octopus 101–Perimeter (Haag–Streit Inc., Koeniz, CH). Stimuli were added by the examiner in order to locally enhance spatial resolution in perimetrically suspicious regions. These areas were characterised by singular or adjacent local visual field defects (VFDs), which were attributable to the retinal nerve fibre bundle course according to the impression of the examiner. Local progression was defined by a slope of local differential luminance sensitivities > 1 dB/yr., and by a residual standard deviation < 3.3 dB + 1.2 yr.×slope [slope–scatter diagram: R. Vonthein et al., IOVS 2004 Abstract No. 235]. Local progression in depth was assumed if the visual field location was assigned as pathological (total deviation p < 0.05) already in the initial session. Progression in size was assumed if the local differential luminance threshold value of the initial session was rated as normal (total deviation p > 0.05). The relative portion of scotoma progression in size was defined by the ratio of the number of VFDs in the final session, characterised by progression in size, and the total number of progressing VFDs within the area of locally condensed stimuli. Unequivocal progression of the visual field was defined by a deterioration of at least three adjacent non–edge locations according to the above mentioned criteria. Results: 26 out of the 69 glaucoma eyes at risk of progression showed an unequivocal deterioration of the visual field. 22 of these revealed a combined progression in depth and size. In 3 eyes there was an exclusive deterioration in depth; 1 eye showed an exclusive VFD progression in size. On average, 36.2% of the progressive test locations were initially normal and therefore indicate progression in size. Conclusions: Increase of visual field loss, as assessed with SCOPE, using locally condensed stimulus arrangements, in glaucoma patients at risk of progression is mainly characterised by a combined deterioration in scotoma depth and size.

Keywords: perimetry • visual fields