Near visual acuity of dental hygienists with and without magnification

The aim of this study was (i) to evaluate the visual performance of dental hygienists in their clinical environment and (ii) to analyse the relationship between self-assessed and objectively measured visual acuity.

The near visual acuity of 191 dental hygienists and dental hygiene students was self-assessed with a visual analogue scale and objectively measured with miniaturized visual tests in a simulated clinical setting. The visual acuity was also measured with magnification aids if they were part of the individual clinical equipment. The influence of age and magnification on the near visual acuity was analysed.

The visual performance with respect to dental working distance showed a variability of 300% in the dimension of the smallest recognized structure. A weak positive correlation between the self-assessed and objectively measured visual performance (Spearman's rank correlation = 0.27) and a highly significant impact of the test person's age and the use of loupes (both P < .0001) were found. Test subjects ≥40 years exhibited a similar visual acuity when using loupes compared to the visual acuity of test subjects <40 years without loupes.

The visual performance with respect to dental working distance cannot be self-assessed and varies individually. Dental hygienists and students of dental hygiene with a weak near visual acuity were not aware of their deficiencies. Optical aids should be used to compensate for individual visual deficiencies and are mandatory above an age of 40 years due to the effects of presbyopia.