MUC16 and synovial sarcoma: To summarize, the possible mechanisms responsible for the manifestation of PPCS are the increase in MUC16 concentration in tears via the shedding of MUC16 accelerated by ocular surface inflammation associated with SS and the accumulation of mucins due to delayed tear clearance, the reduction in repulsive forces between the corneal surface due to the shedding of MUC16 and the increased mucins in tears, and the increased friction due to aqueous tear deficiency in SS (Figure 4).