Cobweb floaters are usually age related. If they are something new for you, I would suggest a comprehensive eye exam.
https://www.mayoclinic.org/diseases-conditions/eye-floaters/symptoms-causes/syc-20372346
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I can't say PMR or prednisone ever caused me to have floaters or blurred vision but uveitis sure did. I think I have seen every type of floater, light flashes and visual disturbance there is . My blurred vision was like a dense fog that would set in so I couldn't see anything. The dense fog was a late stage of uveitis after all the floaters. I had an autoimmune type of uveitis which was treated with high doses of Prednisone.
https://www.mayoclinic.org/diseases-conditions/uveitis/symptoms-causes/syc-20378734
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My main side effect from Prednisone that caused an eye problem was early onset cataracts at the age of 40. I have had the same lens implants for 30 years

Ocular hypertension was a problem but I also have thick corneas so I can relate to what @thenazareneshul writes about. My eye pressures were treated when they would get in the 30's and 40's when I was on higher doses of Prednisone. When I was on lower doses of Prednisone my eye pressures stayed in the 20's and were usually not treated. Now that I'm off Prednisone, my eye pressures are normal so less than 20. I had Prednisone induced glaucoma which is improving.
https://www.aao.org/eyenet/article/management-of-steroid-induced-glaucoma