Table 2.

General characteristics of included studies

First author	Years	Country	Design	Mean age	Gender (male percentage)	NLR cutoff value	Sensitivity	Specificity	BCVA	NAION group		Healthy controls		Healthy control definition	Exclusion criteria	NAION phase	NOS score
										N	NLR	N	NLR
Polat [19]	2015	Turkey	R	60.1	51.11%	1.94	60	63	3.13	45	2.44 ± 1.00	50	1.85 ± 0.50	Subjects without any systemic disease	Other ocular pathologies, using antiplatelet or anticoagulant agents, malignancy, coronary artery disease, chronic liver or heart disease	Acute	7
Gunes [15]	2017	Turkey	R	54.7	42.9%	1.64	85	41	1.08	56	3.62 ± 4.37	56	2.09 ± 0.96	Subjects without any systemic disease	Other ocular pathologies, neurological disease, chronic autoimmune disease or inflammatory disease, active infection,	Acute	6
Inanc [16]	2018	Turkey	R	66.66	41.66%	2.25	66	73	–	33	2.04 ± 0.42	35	1.97 ± 0.31	Healthy people from outpatient clinic of ophthalmology with simple refractive errors	Other ocular pathologies, alcohol abuse, chronic smoking, inflammatory diseases, atrial fibrillation, any systemic disease, hepatic or renal failure	Acute	6
Kocak [17]	2020	Turkey	R	64.7	42.85%	1.79	71	59	–	50	2.57 ± 1.49	44	1.98 ± 1.05	Healthy people from outpatient clinic of ophthalmology	Other ocular pathologies, using medications that may affect blood parameters, chronic inflammatory disease or autoimmune disease, any systemic diseases	Acute	7
Pinna [18]	2021	Italy	R	–	–	_	_	_	–	37	2.44 ± 0.99	37	1.95 ± 0.81	Subjects without NAION	Not declared	Acute	7
Sinsawad [20]	2021	Thailand	R	59.20	56.7%	1.89	66.7	65	–	30	2.25 ± 0.95	30	1.96 ± 0.90	patients with cataract without any systemic disease	Using any kind of treatment for NAION, other neuro-ophthalmic diseases, glaucoma diseases, retinal diseases, alcohol drinking and smoking, underlying disease that can affect the blood test results	Acute	7

N: Number; NLR: Neutrophil-to-lymphocyte ratio; R: Retrospective; BCVA: best-corrected visual acuity; NOS: the Newcastle–Ottawa scale