This paper presents an implantable device concept with applications for treating ocular diseases such as glaucoma, age-related macular degeneration (AMD), diabetic retinopathy, and retinitis pigmentosa. The design of a biodegradable drug delivery device concept consisting of a polydimethylsiloxane (PDMS) shell with a fluid reservoir and micro/nanofluidic tubes that allow the drug to be stored and delivered at a specified rate is discussed. Computational fluid dynamics simulations were conducted through various tube configurations in order to obtain the drug diffusion characteristics. The results from the simulation studies revealed information related to drug transport under varying design parameters. The design simulations were conducted with a desired rate. Based on results from several simulations, an optimization study was conducted to achieve the required dosage for about 2 years. The results obtained from the optimization study shows that the device concept can be extended for different drugs to treat ocular diseases.