Not a rumor. Had 4 pairs (large, medium and small juvi's.) Two in cool water system, two others shared with 20 plus other pairs of clowns (tricinctus, frenatus, occ, perc, GSM, akyndinos, allardi, caps, black polymnus, etc.) All went blind w/in a year. No other clowns affected.
eco-tropic had the same thing happen with all his broodstock. He had lots more latz than I.
I don't have any clue as to why. Mine weren't jumpy, no signs of trauma to the eyes and no other fish ever affected. Received mixed food with mixed seafood, vitamins, Nori, Selcon, etc.