Comparison between two fast threshold strategies: SPARK and SITA in normal subjects

Abstract

Background Numerous fast threshold strategies have been developed in perimetry which use maximum likelihood approaches to estimate the threshold. A recent approach to threshold estimation has been developed estimating the threshold from a limited number of test points which further reduces examination time. This strategy, SPARK, has not been compared to the SITA strategy. The aim of this study was to compare SPARK with SITA in a normal cohort to evaluate within and between strategy agreement in threshold estimates. Methods A total of 83 normal subjects each underwent two visual field examinations with SITA and SPARK on two separate occasions on a randomly selected eye. The eye examined and the order of strategy examined first was randomised but remained constant over the two perimetry visits. Results Visual field examination with SPARK Precision was on average 33% faster than SITA Standard. A positive correlation between group mean sensitivities of SITA Standard and SPARK Precision (rho = 0.713, p < 0.001) was found. In total, 95% of stimulus locations were located within the 95% limits of agreement and linear regression on the differences in sensitivities showed no statistically significant proportional bias (t = 1.713, p = 0.09). Pointwise analysis showed SITA Standard had significantly larger variability for individual stimulus locations examined over two visits when compared to SPARK (t = 9.175, p < 0.001). Conclusion The clinical examination of SPARK yields a sensitivity profile similar to SITA but in a faster examination time. The lower threshold variability of SPARK may be as a result of data smoothing in the threshold estimation process.

Comparative quantification of focal and diffuse visual field loss by the SPARK Precision threshold algorithm and SITA

“…Previous investigations in healthy subjects revealed a higher MS in SPARK Precision compared to SITA Standard [13,21]. In this study of glaucoma and cataract patients, the MS of SPARK Precision was on average 1 dB higher than for SITA Standard.…”

“…Lorch et al suggest that this higher MS value may be due to a higher start value in SPARK. Indeed, threshold responses in SPARK Precision are interpolated from acquired thresholds at limited stimulus locations whereas each stimulus location in SITA is derived from independent assays at each stimulus location and therefore is influenced more by subject variability [13].…”

“…New visual field algorithms, such as SPARK Precision (Oculus Optikgeräte GmbH, Wetzlar, Germany), have previously been shown to reduce the testing time [13] and provide comparable results in respect to mean sensitivities when compared to the widely used Humphrey Field Analyser (HFA) [13].…”

Visual fields in glaucoma: Where are we now?

“…31 SPARK is reported to have a significantly smaller inter-visit variability and a similar sensitivity to SS. 31 ZETA Fast uses the 24-2 pattern and is performed on Optopol Technology perimeters. 32 Compared to SF, it is 23 and 49 s slower in healthy and glaucoma patients, respectively.…”

“…Even though TOP has been reported to underestimate focal visual loss, TOP and SF have similar sensitivities of 84.7%–85.2% and 86.4%–89.2%, and similar specificities of 76.5%–86.7% and 80.0%–93.8%, respectively 30 . SPARK is a strategy that can be implemented on the Oculus perimeters 31 . The 33% reduction in test duration compared to SS can be credited to its use of statistical relationships between neighbouring test points of the visual field, which is generated from 90 000 perimetry results using the strategy 31 .…”