There is no doubt isothiazolinone (and its derivatives) is connected with my puffy eye. As soon as I stopped using fabric conditioner and washed my pillow cases without it, my morning facial swelling stopped. The swollen eye improved but did not entirely go away. Drinking more water stopped the increased swelling evident on waking up. I suspect chronic dehydration caused by lots of tea and coffee drinking, rather than plain tap water, has increased my susceptibility to allergies.
However my eye is still puffy, even though it is less so. I read somewhere that wheat, gluten, eggs and cow’s milk can sometimes be responsible for allergies (or intolerances). Some of the visible signs of these allergies are puffy or swollen eyes.
As an experiment I will be giving up gluten (including wheat, barley, rye and just to be safe porridge), eggs and cow’s milk for about a week or two. This is difficult as many items of prepared food contain cow’s milk or butter.
I will also be taking supplements of quercetin, cysteine, MSM and DHA/EPA (fish oils) as they supposedly help with allergies.