# A Systematic Review of the Usability of Telemedicine Interface Design for Older Adults
## 3 Results
### Factors Affecting the Usability of Interface Design
#### 3.2.3 Visual Design  
The telemedicine interface for the elderly should be clear and straightforward, incorporating effective layouts, graphics, colors, fonts, language, and icons to facilitate the quick completion of medical tasks. It must address the visual, technical, physical, emotional, and cognitive needs of elderly users by utilizing large fonts, clear outlines, and high-contrast colors to enhance the readability [76]. Five key considerations that should be considered when designing interfaces specifically tailored for older adults are as follows:  
_(1) Colors._ Choosing appropriate colors for older users requires the careful consideration of both their preferences and visual abilities. Older adults generally favor blue and pink fonts on blue or turquoise backgrounds, and it is advisable to limit the color scheme to three colors while categorizing information and respecting cultural beliefs, such as the use of blue, green, and black in Arabic mobile health applications [19; 54]. High-contrast combinations, like red text on neutral backgrounds, improve the readability and recognition, whereas yellow text is harder to discern and should be avoided [58; 60; 77]. To enhance accessibility, designs should use vivid, high-contrast colors, large fonts, a cohesive color palette, and ensure screen reader compatibility [60; 66]. Additionally, color schemes should align with content meaning, such as using pain scale colors to reflect severity levels, where the yellow-to-red gradient is a recognized sequence [73]. _(2) Shape, icon buttons, and labels._ Compared to round shapes, older adults generally prefer rectangular shapes [54]. The interface design should be concise and clear, featuring distinct labels and themes [13]. Icons should combine simple, multi-functional symbols with accompanying text and use large buttons for easy clicking, while ensuring visual appeal [73]. Skeuomorphic designs that mimic real-world objects are particularly effective for older users, improving comprehension compared to minimalist styles [61]. Since older adults tend to favor text labels over abstract icons, icon designs should adopt familiar styles [77]. Additionally, live links must be clearly distinguished from icons and text to prevent accidental clicks, and links should avoid opening in new windows to reduce confusion [13]. _(3) Font._ Font size plays a significant role in interface readability, with larger fonts enhancing the usability for older users [58; 59; 78]. A minimum font size of 18 pt is recommended, with Proxima Nova and Arial being the preferred sans-serif fonts due to their high recognition [54]. While some studies suggest 12 pt for body text and 14 pt for titles [12], employing a font size of 22 pt can reduce the operation time for seniors, improving their performance to levels comparable to younger users [67]. Factors such as font appearance, spacing, alignment, and background also influence the readability. It is advisable to use adjustable fonts, clear text, bold key information, contextual explanations, and ensure good contrast between the text and background [13; 60; 69; 70]. Font size standards may vary by language, which can affect the legibility. _(4) Layout._ The layout design should consider users' reading and writing habits, such as the right-to-left orientation preferred in Arabic culture [19]. The content must be logically organized to ensure a clear reading order and task flow, with a consistent placement of logos and buttons [70]. Each page should include navigation buttons, and the functional layout should prioritize the portability [60]. Familiar interfaces enhance the predictability and comprehension; therefore, maintaining a consistent layout and standard page design is essential for improving the usability [13]. _(5) Data visualization._ Data visualization is crucial for self-tracking technology as it aids in identifying trends and promoting behavioral changes. However, design guidelinesfor the elderly remain unclear and require empirical research [77].