The Single Letter chart is displayed by selecting the Sing icon on the Primary toolbar, pressing F3 on the keyboard of selecting Single on the remote control handset.




The Thomson Test Chart allows up to five letter / optotype sets to be defined for each optotype for the LogMAR chart.  The Optotype Sets are selected by selecting the O icon on the Secondary Toolbar or by pressing O on the keyboard or remote. The Single Letter chart uses the same letter/optotype sets as the LogMAR chart. Pressing the horizontal control keys on the keyboard or IR remote control will select the next/previous letter from the five defined.


The five defined letter/optotype sets can be customised by selecting Customise letter sets on the LogMAR tab of the Settings screen. Defining letter/optotype sets.


The Single letter chart uses a logMAR progression of letter sizes.  


The Thomson Test Chart provides a wide range of options for customizing the Single Letter chart. These options may be selected using the Secondary toolbar or by using the keyboard or remote control.



These options are described under Test Charts - common features and include: