Jim's book talks about using MMS for the eye, so we tried it and found that it irritated his eye terribly. In our case, the 25% DMSO worked much better and continues to be one of the most important treatments for him.
To be exact, we use 20 drops of DMSO and 2.5 ml of distilled water, so assuming 20 drops = 1 ml, it is more like 28%. It seems to work better if you make it fresh each time, in which case, we just use one drop of DMSO and 3 drops of water then 1-2 drops of that mixture into each eye.
I recently tried to work some colloidal silver into this, and he didn't respond well, so we backtracked to DMSO only. However, this is not a recommendation, just a data point for you to consider based on your own circumstances.
As far as increasing your MMS dose, it gets hard to stomach above 4 drops for me, and if you go too fast, your body may become repulsed by it. We take ours with MSM water, which we make using 7 Tbsp MSM into 1 L of purified water mimicking the protocol linked below, and that helps a lot with the taste (if you don't mind the taste of the MSM).
websterkehr.com/msm_cd/ 
