The poem seems to be talking about vision using the word "light". However, it doesn't directly say that it is about vision. Therefore, having some knowledge about Milton can provide some aid in figuring out what the poem is trying to express. Being familiar with John Milton's work, one will know that the author went blind, but still didn't give up on writing. In fact some of his best work came after he was blind. So the poem can relate either to Milton's struggle or anyone else's.
The title of the poem can suggest that Milton looks back on how he spent his life while he saw light, in other words, while he still possessed his sight. When Milton states "Ere half my days in this dark world and wide"(2), this shows that he is actually talking about his current state. He has been living in darkness and cannot see light. When Milton says, "And that one talent which is death to hide Lodged with me useless"(3-4), He can be referring to the "talent" as some form as a skill. However, this word can have more than one meaning. Being familiar with biblical scripture will show that in the book of Matthew, there is a parable which talks about a"talent" as a currency. A lord gives talents to his servants in order for them to use those talents and get more out of them. Therefore, Milton is comparing the talent in the parable to his own talent, meaning that he can't do as much as he wants for his Lord, which he later supports with "though my soul more bent