How do macromolecules (large drugs) in the eye reach the bloodstream and what are the relative significances of these pathways?
Antibodies are a unique case.  I recommend reading PubMedID: 26726925 regarding the pharmacokinetics of ranibizumab (Lucentis), a Fab fragment, after intravitreal administration.

"We assume that the principal pathway for the ocular clearance of large molecules is by a first-order transfer process from the vitreous to the aqueous chambers, from which the molecule is absorbed into the circulation via Schlemm’s canal by the physiological process of aqueous humor turnover."

A comprehensive analysis of the pharmacokinetic processes are included in the mechanistic model that they have developed.  I will not copy and paste them here.