Senior citizens and people with retarded vision may find it difficult to see and read what appears on the screen of their PC. You can increase font size of documents you have, but it will not help you in magnifying various Windows control elements and menus.
You may take help of Magnifier tool (Start Menu ⇒ Accessories ⇒ Ease of Access ⇒ Magnifier). The tool temporary magnifies the portion of the screen centering your mouse. But the color quality degrades and contents go out of the screen, which is difficult when you want to keep your eyes on every corner of the Window.
Another tool, which also comes with Windows is less known to people. Actually this is not a tool, but a setting to permanently enlarge the screen by 125%.
Changing the Settings
1. Go to Control Panel ⇒ Appearance and Personalization ⇒ Display.
or, Control Panel (small icon view) ⇒ Display
2. Select Medium zoom which will enlarge the screen by 125%. And apply the changes.
You may need to log off after changing the setting.
This will go permanent and you need not to set this every time you turn on your computer. Settings can be reverted by following the same path.