We investigate how problems in understanding text – specifically a word or a sentence – while filling in questionnaires are reflected in gaze behaviour. To identify text comprehension problems, while filling a questionnaire, and their correlation with the gaze features, we collected data from 42 participant. In a follow-up study (N=30), we evoked comprehension problems and features they affect and quantified users’ gaze behaviour. Our findings implies that comprehension problems could be reflected in a set of gaze features, namely, in the number of fixations, duration of fixations, and number of regressions. Our findings not only demonstrate the potential of eye tracking for assessing reading comprehension but also pave the way for researchers and designers to build novel questionnaire tools that instantly mitigate problems in reading comprehension.