Parsing multiple items from single SNMP OID line

[rex.mbr]

Got 100G switch that reports optical signal level for multiple lanes of 100G interface at single OID as string
Example:
$ snmpwalk -cbcomsnmpadmin -On -v2c 172.16.130.124 enterprises.2011.5.25.31.1.1.3.1.32.16850434
.1.3.6.1.4.1.2011.5.25.31.1.1.3.1.32.16850434 = STRING: "-675.72,-675.51,-660.35,-770.83"
How can I split this answer into 4 items and convert them to numeric?