Working distance and eye and head movements during near work in myopes and non-myopes.

PURPOSE

Reasons for the development and progression of myopia remain unclear. Some studies show a high prevalence of myopia in certain occupational groups. This might imply that certain head and eye movements lead to ocular elongation, perhaps as a result of forces from the extraocular muscles, lids or other structures. The present study aims to analyse head and eye movements in myopes and non-myopes for near-vision tasks.

METHODS

The study analysed head and eye movements in a cohort of 14 myopic and 16 non-myopic young adults. Eye and head movements were monitored by an eye tracker and a motion sensor while the subjects performed three near tasks, which included reading on a screen, reading a book and writing. Horizontal eye and head movements were measured in terms of angular amplitudes. Vertical eye and head movements were analysed in terms of the range of the whole movement during the recording. Values were also assessed as a ratio based on the width of the printed text, which changed between participants due to individual working distances.

RESULTS

Horizontal eye and head movements were significantly different among the three tasks (p = 0.03 and p = 0.014, for eye and head movements, respectively, repeated measures ANOVA). Horizontal and vertical eye and head movements did not differ significantly between myopes and non-myopes. As expected, eye movements preponderated over head movements for all tasks and in both meridians. A positive correlation was found between mean spherical equivalent and the working distance for reading a book (r = 0.41; p = 0.025).

CONCLUSIONS

The results show a similar pattern of eye movements in all participating subjects, although the amplitude of these movements varied considerably between the individuals. It is likely that some individuals when exposed to certain occupational tasks might show different eye and head movement patterns.