Systems, compositions, methods, and kits for identifying potential therapeutic agents for treatment of complement based ocular diseases are provided herein. The methods and kits include a complement component 3 (C3) protein or derivative that is contacted to ocular cells or tissue. Another embodiment of the invention herein provides for diagnosis and/or prognosis of a complement-associated ocular disease. Compositions, methods and kits for regulating or treating a complement-related condition using at least one of CD46 protein, CD55 protein, and a recombinant chimeric soluble terminator of activated complement (STAC) protein or source of the STAC protein. The STAC protein includes an amino acid sequence including at least two of an amino acid sequence of a CD59 protein, an amino acid sequence derived from a CD46 protein, and an amino acid sequence derived from a CD55 protein, optionally further comprising a linker to connect amino acid sequences.