There is no single answer to this question as it may depend on the individual's specific case. However, there are a few things to consider if you're experiencing brain fog and you wear glasses or contacts.
Glasses and contact lenses
If you're finding that your glasses or contacts are causing your brain fog, it's possible that you may be experiencing eye fatigue. This can be caused by staring at a computer screen for too long, reading in low light, or not taking regular breaks from looking at screens. If you think this may be the case, try taking a break from your glasses or contacts for a day or two and see if your symptoms improve.
Brain fog can also be caused by actual vision problems. If you've had an eye exam and been told that you need glasses or a change in prescription, it's possible that the new lenses are actually affecting your ability to think clearly. In some cases, people have found relief by switching back to their old prescription.
There are also certain medical conditions which can cause brain fog. Conditions like hypothyroidism, diabetes, and menopause can all lead to changes in cognitive function. If you think one of these conditions may be causing your brain fog, consult with your doctor about getting tested.