A Comparative Validation Study of Near Visual Acuity Assessment Using Different Handheld Acuity Charts

Objective

To develop a conversion table and compare the cross-validity of 3 types of widely utilized near vision charts: the ETDRS near chart, the N-notation chart, and the Rosenbaum chart.

Design

A prospective, cross-sectional, comparative validation study.

Participants

Aged ≥40 years.

Methods

A conversion table for the 3 types of near charts was created using objective character sizing based on vertical height captured using a surgical microscope with a 10× magnification. Eligible presbyopic patients had their near vision tested sequentially with 3 near charts in a randomized order.

Main Outcome Measures

Pearson correlation coefficient (r) for the relationship among the near visual acuity charts. The consistency between the different charts was evaluated by Bland−Altman diagrams.

Results

A total of 204 participants (129 women, 63.2%) were recruited for the study (mean age, 58.9 ± 7.1 years). For correlation, r ranged from 0.596 to 0.836 (all P < 0.001). The Rosenbaum chart had the smallest range of difference against the ETDRS chart (standard deviation [SD] = 0.12), followed by the N-notation chart (SD = 0.15). Most of the converted logarithm of the minimum angle of resolution (logMAR) values from the N-notation and Rosenbaum charts were between 0.0 and 0.1 higher than the ETDRS logMAR equivalent (range: 0.07–0.11), with a tendency for both the N-notation and Rosenbaum charts to overestimate logMAR at more positive values.

Conclusions

We have developed a conversion table for 3 types of commonly used near vision charts. When compared with the ETDRS near chart, the Rosenbaum chart had a smaller range of difference than the N-notation chart. Both the Rosenbaum and N-notation charts tended to underestimate near vision at worse vision.

Financial Disclosure(s)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.