In the present study, education majors minoring in music education (n = 24) and music performance majors (n =14) read and performed the original version and melodically altered versions of a simple melody in a given tempo. Eye movements during music reading and piano performances were recorded. Errorless trials were analyzed to explore the adjustments of visual processing in successful performances. The temporal length of the "eye-hand" span (time between gaze and the performed note) was typically around one second or less. A measure of "gaze activity" indicated that performers generally inspected two quarter-note areas between two metrical beat onsets. The performance majors operated with shorter fixation durations and applied larger eye-hand spans as well as greater gaze activity than education majors. The latter two measures were generally affected by unexpected melodic alterations and simple rhythmic patterns. The study manifests both the flexibility and limitations of the mechanisms of visual processing in temporally controlled music reading, addressing some of the everyday conceptions about sight-reading by means of systematic research.