visual acuity vs prescription

[eifgs]

Hi,

While browsing the web recently I came across following acuity to prescription strength table:

—.50 D 20/50
—1.00 D 20/100
—2.00 D 20/200
—3.00 D 20/300
—4.00 D 20/400
—5.00 D 20/500
—6.00 D 20/600
—7.00 D 20/700
—8.00 D 20/800
—9.00 D 20/900
—10.00 D 20/1000

Which made me wonder about the accuracy of my prescription. My prescription is -1.5 in both eyes with astigmatism of -0.5 and -0.75 respectively. However during my last eye exam I could read the 20/50 and 20/80 lines with my respective stronger and weaker eyes. The Dr wrote it down on my result sheet.

Could my poor vision be due to some factor that a regular eye test can not detect, but is still corrected with a stronger than necessary prescription?

[John C Hagan]

I would not put much stock in your "finding" on the web. I doubt if it has any basis in fact. Plus a patient with normal eyes and a RX of -2.00 will see 20/20 at 18 inches and the visual acuity will continue to change out to 20 feet.

JCH III MD