Prevalence and causes of visual impairment and rate of wearing spectacles in schools for children of migrant workers in Shanghai, China

Table 5 Causes of visual impairment*

	Right eye	Left eye	Children with visual impairment	Prevalence in the population (%)
	Right eye	Left eye	n (%) (one or both eyes)*	(one or both eyes)*
Refractive error†	1478	1447	1795 (89.48)	18.87
Amblyopia	147	188	203 (10.12)	2.13
Ocular prosthesis	0	2	2 (0.10)	0.02
Congenital nystagmus	2	2	2 (0.10)	0.02
Congenital cataract	2	2	2 (0.10)	0.02
Macular degeneration	1	1	1 (0.05)	0.01
Opaque cornea	1	1	1 (0.05)	0.01
All	1631	1643	2006 (100.00)

Data show the frequency (%) of cases.
*Children with visual acuity ≤ 20/40 in both eyes may represent two separate causes of reduced vision, one in each eye.
†Refractive error was assigned as the cause of reduced vision for all eyes correcting to ≥ 20/32 with subjective refraction, even if other contributing diseases were present.

ISSN: 1471-2458