Visual acuities "hand motion" and "counting fingers" can be quantified with the freiburg visual acuity test.

PURPOSE The visual acuity (VA) of patients with very low vision is classified using the semiquantitative scale "counting fingers" (CF), "hand motion" (HM), "light perception" (LP), and "no light perception." More quantitative measures would be desirable, especially for clinical studies. The results of clinical VA measurements, Early Treatment Diabetic Retinopathy Study (ETDRS) charts, and the Freiburg Visual Acuity Test (FrACT) were compared. The FrACT is a computerized visual acuity test that can present very large Landolt C optotypes when necessary. METHODS Examined were 100 eyes of 100 patients with various eye diseases (e.g., diabetic retinopathy, ARMD), covering a range of VAs from LP to decimal 0.32. The FrACT optotypes were presented on a 17-inch LCD monitor with random orientation. After extensive training, two ETDRS and FrACT measurements were obtained. The testing distance was 50 or 100 cm. RESULTS ETDRS and FrACT coincided closely for VA > or = 0.02 (n = 80). ETDRS measures were successfully obtainable down to CF (at 30 cm; test-retest averaged over all patients, coefficient of variation [CV](ETDRS) = 9% +/- 8%), and FrACT provided reproducible measurements down to HM (test-retest CV(FrACT) =12% +/- 11%). For CF (n = 6), both ETDRS and FrACT resulted in a mean VA of 0.014 +/- 0.003 (range, 0.01-0.02). The VA results of FrACT for HM (n = 12) were 0.005 +/- 0.002 (range, 0.003-0.009); the individual values were highly reproducible. No results were obtainable for LP (n = 2). CONCLUSIONS The three acuity procedures concur above a VA of 0.02. The results suggest that the category CF at 30 cm can be replaced by 0.014, using ETDRS or FrACT. Using FrACT, one can even reproducibly quantify VA in the HM-range, yielding a mean VA of 0.005.

[1]  I L Bailey,et al.  New Design Principles for Visual Acuity Letter Charts* , 1976, American journal of optometry and physiological optics.

[2]  Recommended stardard procedures for the clinical measurement and specification of visual acuity. Report of working group 39. Committee on vision. Assembly of Behavioral and Social Sciences, National Research Council, National Academy of Sciences, Washington, D.C. , 1980, Advances in ophthalmology = Fortschritte der Augenheilkunde = Progres en ophtalmologie.

[3]  F L Ferris,et al.  Standardized illumination for visual acuity testing in clinical research. , 1982, American journal of ophthalmology.

[4]  F. Ferris,et al.  New visual acuity charts for clinical research. , 1982, American journal of ophthalmology.

[5]  Alex Pentland,et al.  Microcomputer-based estimation of psychophysical thresholds: The Best PEST , 1982 .

[6]  I L Bailey,et al.  Clinical grading and the effects of scaling. , 1991, Investigative ophthalmology & visual science.

[7]  A Arditi,et al.  On the statistical reliability of letter-chart visual acuity measurements. , 1993, Investigative ophthalmology & visual science.

[8]  B. Treutwein Adaptive psychophysical procedures , 1995, Vision Research.

[9]  M. Bach,et al.  The Freiburg Visual Acuity test--automatic measurement of visual acuity. , 1996, Optometry and vision science : official publication of the American Academy of Optometry.

[10]  M. Bach Anti-aliasing and dithering in the 'Freiburg Visual Acuity Test'. , 1997, Spatial vision.

[11]  J T Holladay,et al.  Proper method for calculating average visual acuity. , 1997, Journal of refractive surgery.

[12]  A. Edwards,et al.  Visual acuity impairment in patients with retinitis pigmentosa at age 45 years or older. , 1999, Ophthalmology.

[13]  Wolfgang Wesemann,et al.  Sehschärfebestimmung mit Freiburger Visustest, Bailey-Lovie-Tafel und Landoltring-Tafel , 2002 .

[14]  Wolfgang Wesemann [Visual acuity measured via the Freiburg visual acuity test (FVT), Bailey Lovie chart and Landolt Ring chart]. , 2002, Klinische Monatsblatter fur Augenheilkunde.

[15]  Lars Loumann Knudsen Visual acuity testing in diabetic subjects: the decimal progression chart versus the Freiburg visual acuity test , 2003, Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie.

[16]  J. Beer,et al.  Using the Freiburg Acuity and Contrast Test to Measure Visual Performance in USAF Personnel After PRK , 2004, Optometry and vision science : official publication of the American Academy of Optometry.