[Presentation of visual acuity in ophthalmological publications]

Abstract

Background: Visual acuity is one of the most important functions of the visual system. Visual acuity is the basis of many decisions in clinical practice. The assessment of visual acuity is clearly defined (norm EN ISO 8596). In this study, the presentation of results of visual acuity assessments in the ophthalmological literature was analysed.

Materials and methods: All the issues of the journals "Klinische Monatsblatter fur Augenheilkunde" and "Der Ophthalmologe" of the years 2002 and 2003 were reviewed especially concerning the procedure of visual acuity assessment, the scaling in the lower visual acuity range, axis scaling and the calculation of mean values of visual acuity.

Results: In total, 550 publications were reviewed. Of these papers, 207 contained at least one visual acuity value and 42 papers presented detailed data concerning either the change of visual acuity over a certain time interval, or mean values, or using charts. A linear scale was used in 9 of 28 papers with presentation of visual acuity measurements in a chart. Of 32 publications with visual acuity measurements less than 0.2, only 2 used a logarithmic scale in the lower visual acuity range, while in 14 papers, scaling was rather rough or not numeric (e. g., counting fingers). Sixteen papers used the units "finger counting" or "hand movements" to describe low visual acuities. The way of calculating mean values remained obscure in 36 papers.

Conclusions: Regarding a correct assessment of visual acuity and the effect of therapy, the fundamental guidelines of visual acuity assessment and its correct presentation should be considered.