J Neurol (2012) 259:1832–1839 Table 6 Results from the pattern glare test detailing mean pattern glare scores for stroke and control participants, with the exclusion of migraine subjects Spatial frequency Score (mean ± SD) Score (mean ± SD) Mid-SF Mid-high difference High-SF 2.82 ± 1.81 2.18 ± 1.38 0.65 ± 0.79 Stroke (n = 17) 1.76 ± 1.44 -0.06 ± 1.14 1.82 ± 1.33 Control (n = 17) Fig. 4 Mean pattern glare scores from the pattern glare test for stroke and control participants, with the exclusion of migraine subjects. Statistically signiﬁcant elevation of pattern glare scores were found for the stroke subjects, when considering the mid-high difference variable The results for this modiﬁed data set (see Table 6; Fig. 4), showed that the stroke subjects exhibited higher pattern glare scores than the control subjects when viewing the mid-SF grating (unpaired t test: t = 1.888, df = 32, p = 0.068), as well as for the relative score of the mid-high difference variable (unpaired t test: t = 5.141, df = 32, p = 0.0000). Consistent with earlier measures, the stroke subjects scored much lower on the pattern glare test, when viewing the high-SF pattern, compared to the control group (unpaired t test: t = -3.133, df = 32, p = 0.004). Discussion The present study has demonstrated that stroke subjects respond with signiﬁcantly higher pattern glare scores than a control population when undertaking the pattern glare test; this elevation in scores being most notable for the mid-high difference variable, a relative score that allows for nor- malization of the subject by taking into account suggest- ibility. Abnormal pattern glare is considered to be present when a subject delivers a pattern glare score of [3 on the mid-SF grating, or a score of[1 on the mid-high difference variable. In fact, 75% of the stroke participants recorded an 1837 abnormal degree of pattern glare when considering the mid-high difference measure, compared to just 5% within the control population. For the stroke participants, the mean score approached the cut-off for abnormality of [3 when viewing the mid-SF grating, but did not exceed it. It was, however, signiﬁcantly higher than the scores of a control group, at a level of statistical signiﬁcance. Further suggestion of elevated pattern glare in the stroke group was shown by a decreased measure on the high-SF grating for stroke subjects versus control subjects. The high-SF mea- sure, which was found to be of statistical signiﬁcance, is usually higher in subjects with a low degree of visual discomfort. These three principal measures were still found to persist even when subjects with potential correlates of pattern glare, namely migraine, were removed from the analyses. It should be noted that the control group were some 10 years younger than the stroke subjects. Estab- lished normative values have shown that with advancing age, there is a greater decrease with the high-SF grating than the mid-SF grating which, in turn, results in a small overall increase in the ‘mid-high difference’ variable, although not at levels of statistical signiﬁcance [6]. Despite a paucity of literature, there is evidence of sensitivity to patterns following traumatic brain injury, including stroke, as determined by analyzing self-test responses to a questionnaire designed to recognize sensi- tivity to glare, light, contrast, bright colors, and patterns [26]. It has also been shown, however, that this indirect method of determining the existence of pattern related visual stress is not as useful as a direct presentation of a patterned stimulus to the individual concerned [36]. Whilst an indirect method of analyzing pattern glare symptoms serves as a useful indicator, it does not appear to isolate those individuals who are more likely to have their symptoms alleviated by an intervention such as a spectral ﬁlter. Since pattern glare results from cortical hyperexcitabil- ity [7, 11], it is perhaps unsurprising that stroke sufferers can be shown to demonstrate abnormal levels of pattern glare; this is in line with evidence of cortical hyperexcit- ability following stroke [32]. Lesion-induced cortical hyperexcitability has also been demonstrated following short transient ischemic attacks [37], suggesting that symptoms of pattern glare could potentially exist in those experiencing milder episodes of so-called ‘mini-stroke’ in the absence of more obvious functional impairment, and represents an opportunity for further work in this area. It would be valuable for future studies to consider the asso- ciation of pattern glare, with co-existing visual deﬁcits, such as visual ﬁeld defects and binocular vision anomalies, in stroke individuals. The present study was limited by a modest sample size, and further work with a larger subject group should be 123