From what I understand, although halorhodopsin can still function within the frequencies of visible light, quality of perception would be greatly reduced when perceiving wavelengths outside the cells’ optimal range. For example, when receiving red light, the object emitting red wavelengths will appear untrue in the patient’s perception because their halorhodopsin cells’ respond to only the yellow/green portions of the red wavelength. This is where the optical device comes in – the device would capture images of the visual field in real time and translate them to the appropriate yellow and green wavelengths in the interest of mimicking true saturation and brightness perception for the patient.

Remember, we are not dealing with normal human photoreceptors anymore once they have been treated with AAV-Halorhodopsin. The LED glasses may be able to shine a mesh of wavelengths on the eyes of the patient that causes perception of other colors based on rates of hyperpolarization for given hues of yellow and green light. Think of a traffic light: because the patient’s halorhodopsin eyes mostly perceive yellow and green, they may not be able to discriminate the red color properly and perceive it inadequately, but the device will maintain the brightness and saturation of the red light so they can react appropriately.

Those are my thoughts, hope they make sense!

I don’t understand one thing though – why would the treatments require an optical device to translate the light wavelengths of a visual field into ones that halorhodopsin “understands”? Wouldn’t the halorhodopsin do the translating itself?

As you say, halorhodopsin functions in the green and yellow wavelength range, but one has to keep in mind that (usually) the protein responds to a wide range of wavelengths, where green (for example) is just the one that activates it the best. So, for example, if our halorhodopsin is exposed to red light, it will still respond, but the perception would be of some shade of green/yellow instead of red.

This is just speculation – I don’t have much background in visual physiology. Thoughts?