 Shares of Second Sight Medical Products Inc. soared 104.2 on heavy volume in midday trading Monday, bringing its two-day gain to 728.7, after the Food and Drug Administration approved the companys Argus 2s Retinal Prosthesis System for the treatment of retinitis pigmentosa RP. The stock paced all gainers on major U.S. exchanges, and was the most actively traded, as trading volume swelled to 222.6 million shares, compared with the full-day average of 26.5 million shares. 