Hi,
Could you give a few more details?
How long have you been low carbing, and how low is your version of low carbing? Did you start off with higher blood glucose which is now dropping?
The 6.8 you quoted, is that an HbA1c result, or a finger prick test? And if it was a finger prick test was it fasting? Before food? 2 hrs after?
Sorry for the barrage of questions, but blood glucose can and does affect the eyes. However, an established low carber would probably have blood glucose that is stable(ish) which wouldn't result in blurry eyes. Whereas a new low carber with levels dropping or fluctuating may experience blurry eyes while they adjust.
And, of course, the blurry eyes may not be connected to low carbing at all... in which case, your doc or optician would be able to give advice.
(I got very blurry eyes following a glucose tolerance test, because my blood glucose went from lowish, to VERY HIGH, then dropped sharply, and the rapid changes made my eyes blurry for a day or so. Couldn't read, drive or see the tv.)