Visual acuity testing in diabetic subjects: the decimal progression chart versus the Freiburg visual acuity test.
OBJECTIVE
To study reproducibility and biological variation of visual acuity in diabetic maculopathy, using two different visual acuity tests, the decimal progression chart and the Freiburg visual acuity test.


METHODS
Twenty-two eyes in 11 diabetic subjects were examined several times within a 12-month period using both visual acuity tests. The most commonly used visual acuity test in Denmark (the decimal progression chart) was compared to the Freiburg visual acuity test (automated testing) in a paired study.


RESULTS
Correlation analysis revealed agreement between the two methods (r(2)=0.79; slope=0.82; y-axis intercept=0.01). The mean visual acuity was found to be 15% higher (P<0.0001) with the decimal progression chart than with the Freiburg visual acuity test. The reproducibility was the same in both tests (coefficient of variation: 12% for each test); however, the variation within the 12-month examination period differed significantly. The coefficient of variation was 17% using the decimal progression chart, 35% with the Freiburg visual acuity test.


CONCLUSIONS
The reproducibility of the two visual acuity tests is comparable under optimal testing conditions in diabetic subjects with macular oedema. However, it appears that the Freiburg visual acuity test is significantly better for detection of biological variation.
Loumann Knudsen
Lars
L
Department of Ophthalmology, Aalborg University Hospital, 9000 Aalborg, Denmark. u19204@aas.nja.dk
D000328:Adult; D000368:Aged; D003930:Diabetic Retinopathy / Q000503:physiopathology*; D004487:Edema / Q000503:physiopathology*; D006801:Humans; D008266:Macula Lutea; D008875:Middle Aged; D015203:Reproducibility of Results; D016037:Single-Blind Method; D014787:Vision Tests; D014792:Visual Acuity