Switch ViaCam is an image detection and keystroke output by Cesar Mauri which can be used instead of the combination of iSpy/Autohotkey script.
It needs to be in the Foreground in Windows for it to work with Grid3, but it is a lot more responsive that the iSpy/Autohotkey combo.
Some configuration of the camera settings may be needed for the Teslong otoscope, although the newer smaller 4x20mm otoscope worked with the default settings.
For Teslong I needed to change the camera configuration to the following to switch to the Teslong otoscope to prevent it crashing:
640x480 , capture speed 5 & a time filter of 500ms approx.
Below is a screen shot of the set up using the 4x20mm otoscope, the Decibullz moulded earplug and Switch ViaCam to type on Grid3 (Grid3 configured to use a "Tab" keystroke as the switch access)