Design approaches to improve Thai font legibility by clarifying idealistic key features using a blur simulation method have been proposed. Specifically, the jutting out of the tail of characters and inclusion of a loop-with-serrated-line, together with sufficient character width, have been found to improve legibility. In the current study, a set of four homologous characters was presented to the parafoveal region with a short-exposure methodology to display the characters with low visual acuity. Overall, the results revealed that most of the chosen idealistic key features enhanced the legibility of characters presented in parafoveal vision. However, the detailed results revealed variation in the amount of confusion between letter pairs for each tested character. These findings suggest the need for several practical improvements by modifying the specific features of each letter. Although the results of the short-exposure and blur simulation approaches differed at times, the findings of both studies suggest possibilities for developing optimal letterforms using a combination of both methodologies.