Technically, one should not isolate lines on the chart unless you are having problems with comprehension. A full chart simulates real vision and is more accurate VA to real life. Isolating lines or letters can reduce "crowding" and artificially improve VA. Also, even with project-o-charts, one should not completely dim the room lights. The room should be moderately dim, but not completely dark for a projected image.
Thanks for this video. Re: the last section at 4:18, why are these pitfalls? Why is it important for testing acuity that they avoid squinting to keep the covered eye open?
Technically, one should not isolate lines on the chart unless you are having problems with comprehension. A full chart simulates real vision and is more accurate VA to real life. Isolating lines or letters can reduce "crowding" and artificially improve VA. Also, even with project-o-charts, one should not completely dim the room lights. The room should be moderately dim, but not completely dark for a projected image.
Thanks for this video. Re: the last section at 4:18, why are these pitfalls? Why is it important for testing acuity that they avoid squinting to keep the covered eye open?
Of course you can and should do this at home, for high accuracy.