Table 2.

Summary of study results linking myopia and high intelligence.

Study	Country	Number of subjects	Age (years)	Range of myopia	Intelligence test performed	IQ	Test/school results	Significance level∗
Young 1955 [14]	USA	633	6–17	Not specified	Stanford-Binet	Average	N/A	P < 0.001 CC∗∗ = −0.19
Nadell and Hirsch 1958 [15]	USA	414	14–18	Not specified	CTMM	Higher	N/A	P > 0.1
Hirsch 1959 [27]	USA	554	6–17	Not specified	Stanford-Binet CTMM	Higher	N/A	P < 0.001
Young 1963 [28]	USA	251	5–17	Not specified	Stanford-Binet CTMM	Average	Higher	CC = −0.11/0.10 CC = −0.17/0.21
Grosvenor 1970 [29]	New Zealand	707	11–13	≥−1.00 D	Otis Test	Higher	Higher	P > 0.05 (versus emmetropes) P < 0.05 (versus hypertropes)
Karlsson 1976 [30]	USA	2527	17-18	Not specified	Lorge-Thorndike IQ Test CTMM	Higher	Higher	P < 0.001
C. P. Benbow and R. M. Benbow 1984 [31]	USA	416	13	Not specified	Scholastic Aptitude Test	Higher	Higher	P < 0.05
Rosner and Belkin 1987 [32]	Israel	157 748	17–19	≤6/7.5 VA	Verbal Otis Test, Raven Matrix Test	Higher	Higher	Strongly positive association
Williams et al., 1988 [13]	New Zealand	537	7–11	≥−0.5 D	WISC-R IQ Test Burt Word Reading Test	Higher	Higher	P < 0.05
Teasdale et al., 1988 [33]	Denmark	15 834	18	≥−0.25 D to ≤−7.5 D	Group IQ Scores Educational levels	Higher	Higher	P < 0.001
Dolezalova and Mottlova 1995 [12]	Czech Republic	225	14–18	Unknown†	School test scores	Higher	Higher	Unknown†
Saw et al., 2004 [34]	Singapore	1204	10–12	≥−0.5 D	Raven Matrix Test	Higher	N/A	P < 0.05
Saw et al., 2006 [35]	Singapore	994	7–9	≥−0.5 D	Raven Matrix Test	Higher	Higher	P < 0.05
Dirani et al., 2010 [36]	Singapore	1143	9-10	≥−0.5 D	Raven Matrix Test	Average	Average	P > 0.38 (9-year-olds) P > 0.27 (10-year-olds)
Akrami et al., 2012 [37]	Iran	137	10–14	≥−0.5 D	Unspecified school tests	Average	N/A	P = 0.465

^* P score < 0.05 denotes statistically significant result.

^∗∗CC: correlation coefficient.

^†Data unavailable in English language at time of the literature review.