Comparison between threshold interpolation and whole-line method by visual acuity testing on logMAR and Snellen chart
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| Year of publication | 2011 |
| Type | Appeared in Conference without Proceedings |
| MU Faculty or unit | |
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| Description | By measuring of the visual acuity (VA), we measure minimum angle of resolution (MAR) of the eye. MAR is defined as an ability to distinguish the two objects in space. MAR is assessed by the distance between two non-neighboring cones on the retina and by average distance from nodal point of the eye to retina. According to this equitation the MAR is equal to 1 minute of arc. Reciprocal amount of MAR is VA. The whole-line measuring of VA according to Snellen has been used since 1862. Snellen chart consists of optotype letters with variable distance between letters and also between rows. The result of this examination is usually noted as a fraction (for example 6/30), where the first number means the examination distance and the second one the distance, from which this row should be readable by a normal eye (MAR is 1 minute of arc). In 1976 Australian optometrists Ian Bailey and Jan Lovie developed special optotype chart with logarithmic distribution of letters, where each letter has its own value (usually 0.02), and we can use the interpolation method by visual acuity testing. The aim of our study was to prove the difference between the threshold interpolation logMARmethod and the whole-line method on ETDRS chart and Snellen chart with Sloan letters. |