Table 1. The characteristics of included studies.

Studies	Year	Retinal feature	Control	Stroke	Mean age	Female ratio	Stroke types	Cigarette smoker
El-Asrar et al[10]	2002	DR	640	8	48.8	47.5%	Prevalent stroke	/
Petitti and Bhatt[11]	1995	DR	52	52	67	48.0%	Prevalent stroke	63.5%
Wong et al[12]	2003	AN	1610	94	78.5	61.1%	Prevalent stroke	56.8%
Longstreth et al[13]	2007	AN	897	496	78.3	60.3%	Prevalent stroke	13.0%
		AVN	939	496	78.3	60.3%	Prevalent stroke	13.0%
Cooper et al[14]	2006	AN	1428	164	62.2	59.8%	Prevalent stroke	20.6%
		AVN	1462	173	62.2	59.8%	Prevalent stroke	20.6%
		Hemorrhage	1422	169	62.2	59.8%	Prevalent stroke	20.6%
		Microaneurysm	1311	151	62.2	59.8%	Prevalent stroke	20.6%
Kwa et al[15]	2002	AN	71	108	61.9	62.0%	Prevalent stroke	6.1%
Kawasaki[16]	2011	SFD	184	101	74	58.0%	Incident stroke	7.3%
Cheung et al[17]	2007	DR	1471	75	60.1	47.0%	Incident stroke	/
		Hemorrhage	1511	79	60.1	47.0%	Incident stroke	/
		Microaneurysm	1474	75	60.1	47.0%	Incident stroke	/
Wong et al[18]	2001	AN	10358	110	53.6	55.7%	Incident ischemic stroke	32.6%
		AVN	10264	94	53.6	55.7%	Incident ischemic stroke	32.6%
		Hemorrhage	10095	92	53.6	55.7%	Incident ischemic stroke	32.6%
		Microaneurysm	9866	89	53.6	55.7%	Incident ischemic stroke	32.6%

/: Not given in paper and unable to calculate from data; DR: Diabetic retinopathy; AN: Arteriolar narrowing; AVN: Arterio-venous nicking; SFD: Spectrum fractal dimension.