20-60 best corrected vision-How?

Just curious-  I have poor corrected vision but have had retina tears detachments and
Macula surgery and docs  understand that- But I am curious  - I have a 7 year old grandson with 20-50 best corrected vision and they cannot find a reason- I have talked to 2 others in the past month with 20-40 and 20-60 best corrected vision and neither of them has had retina detachments or anything that the docs can find.

How is it possible to have worse  than 20-20 corrected vision with no apparent injuries ??
Is this something that happens ?? I never heard of that before .

Just curious- the lady I talked to today ( 49 YO )  has been to several Nationally know eye centers ( 20-60 best corrected vision and no one can find a solution for her ) and is seeing my Retina doc
now  ( don't know how she made out today but I had my best Retina exam in two years   YEA!!!!!!!!! )

Just sounds strange- I have had high perscriptions throughout my adult life but always 20-20 before my recent
surgery issues .

[John C Hagan III, MD, FACS, FAAO]

The problem you describe is VERY COMMON.  First there may be causes in the eye that are not apparent or not discovered. The eye may be amblyopic. The eye may be normal but there may be problems in the optic nerve, optic chiasm, optic radiations, optic tracts or visual cortex.

Also visual acuity is distributed along the Bell Curve so that mean (average) visual acuity is 20/20 but there are people on both sides of the average that may see better or worse than 20/20 based on intrinsic differences in the strength of the eye.  Everyone understands that some people are stronger, faster, smarter than others  vision is the same.

JCH III MD