A novel and cheap method to correlate subjective and objective visual acuity by using the optokinetic response
To describe a novel optokinetic visual acuity estimator (Oktotype) and to report the preliminary results obtained in poorly and non-collaborative subjects.
Eleven series of symbols arranged horizontally and moving from left to right at a constant rate were displayed. In each sequence, the size of the stimuli was reduced logarithmically. By using this paradigm, the objective visual acuity was computed in 26 normal subjects as the minimum size of the symbols able to evoke the optokinetic response. In the preliminary phase, three contrast levels were tested, with white noise added to the first five sequences so as to normalize the overestimate found at the lower-half range of the acuity scale. Subsequently, the correspondence between subjective and objective visual acuity was compared in 10 poorly collaborative subjects, and the agreement between optokinetic and Teller visual acuity was measured in six non-collaborative subjects.
The best agreement is provided by the minimum contrast level (20%) (R 2 = 0.74). The correspondence between the two techniques is satisfying both in the normal and in the poorly collaborative sample (concordance correlation coefficient: 0.85 and 0.83, respectively). In the non-collaborative group, the concordance correlation coefficient between Teller acuity and OKVA ranged between 0.79 (test) and 0.85 (retest). Test–retest reliability was very good for the Oktotype (K: 0.82), and better than the Teller test (K = 0.71), even if it was lower compared to Snellen acuity (K = 0.95).
The Oktotype seems promising to predict Snellen visual acuity in normal and poorly collaborative subjects.
KeywordsAgreement Non-collaborative patients Oktotype Optokinetic nystagmus Teller cards Test–retest reliability Visual acuity
No funding was received for this research.
Compliance with ethical standards
Conflict of interest
All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
- 1.West SK, Munoz B, Rubin GS, Schein OD, Bandeen-Roche K, Zeger S, German PS, Fried LP (1997) Function and visua impairment in a population-based study of older adults. Opthalmol Vis Sci 38:72–82Google Scholar
- 3.Levenson JH, Kozarsky A (1990) Visual acuity. In: Walker HK, Hall WD, Hurst JW (eds) Clinical methods: the history, physical, and laboratory examination, vol 3. Butterworth Ed, BostonGoogle Scholar
- 21.Kim MS, Choi YS, Lu WN, Lee K, Hwang GM, Wee WR, Lee JH (2000) The development of an objective test for visual acuity assessment using optokinetic nystagmus stimuli presented head-mounted display: sreohan objective visual acuity test. J Korean Ophthalmol Soc 41:871–878Google Scholar
- 39.Altman DG (1991) Practical statistics for medical research. Chapman and Hall, LondonGoogle Scholar
- 47.Ludvigh E, Miller JW (1953) A study of dynamic visual acuity. U.S. Naval School of Aviation Medicine. Res Report No. NM 001 075.01.01Google Scholar
- 48.Marx MS, Werner P, Fridman P, Cohen-Mansfield J (1989) Visual acuity estimates in the aged. Clin Vis Sci 4:179–182Google Scholar