Sjogren's can cause problems for our vision, so you'll want to use eye drops regularly and see your eye doctor once or twice a year. If you do that, you shouldn't have to worry about blindness.
As for plaquenil, here's my favorite explanation from Dr. Daniel Wallace's The Lupus Book: "My pet peeve is that too many lupus patients have been frightened away from antimalarials by doctors who warn them about potential eye toxicity. First of all, quinacrine does not affect the eyes in currently used doses. Second, eye toxicity caused by HCQ is extremely unusual [. . .] If a lupus patient sees a retina specialist every 6 months, the deposits will be noticed before they cause any symptoms, and if the drug is stopped, the deposits will disappear in weeks."
People with any AI disease take about the same dosage of plaquenil (usually 400 mg/day), so this information applies to us, too. Dr. Wallace is considered an expert in rheumatology (he has also written books about Sjogren's); he's definitely a reputable source.