Starting from Tesseract 3.05.00 the Add to Path checkbox was removed, as it caused problems. UB-Mannhaim documentation:
Old versions of the installer had an option to add Tesseract to the
PATH environment variable. That option was disabled by default. If it
was enabled and PATH was very long, it could happen that the new PATH
was empty. We suggest not to use that option and disabled it in our
latest version.
Following the UB-Mannhaim recommendation, instead of adding PATH to system variables you can always consider setting a local variable in your code.
Example from pytesseract documentation:
# If you don't have tesseract executable in your PATH, include the following:
pytesseract.pytesseract.tesseract_cmd = r'<full_path_to_your_tesseract_executable>'
# Example tesseract_cmd = r'C:\Program Files (x86)\Tesseract-OCR\tesseract'
Another example for pyocr:
pyocr.tesseract.TESSERACT_CMD = r'<full_path_to_your_tesseract_executable>'