The diseases that occur related to cornea, conjunctiva, and pigmented vascular regions of the eye are keratitis, conjunctivitis, and uveitis . Antimicrobial eye drops were used for these infections. In common the tear film enclosing these tissues, the residence time at the tissue site was reduced significantly. In the case of nanoparticle-based drops, the interaction with mucins was produced by the epithelia through hydrogen bonding and electrostatic interactions. Thus, the ocular residence time is increased significantly and prevents inflammation .
Therefore, adhesive agents and eyedrops made through nanoparticles were developed.
If causes any disturbance to the cornea, there seems to be damaged in the tissue itself. The wound that is caused due to damage involves the wound healing process in the cornea which causes scar and angiogenesis, which leads to disturbance in vision. To avoid postoperative complications after surgery adhesives , polymer glue , and dendrimer-based hydrogels  on nanoscale were developed. The use of nanoscale products improved the wound healing process effectively.
Corneal neovascularization is the formation of blood vessels in the avascular corneal tissue. This can lead to inflammation, infection, and traumatic diseases . The commonly advised therapies are corticosteroids, nonsteroidal anti-inflammatory eye drops, photodynamic therapy, photocoagulation, and antibody [9, 10]. The inhibitors that are used for impeding the process are VEGFs, platelet-derived growth factors, fibroblast growth factors, metalloproteinase, and interleukins. It is identified that VEGF-based receptors were used to decrease the vascularization of the cornea [11-13].
Retinoblastoma is retinal cancer that is found in 1 in 15,000 to 20,000 births .
The treatments that are found at present are enucleation, radiation therapy, and chemotherapy. The chemotherapeutic agents reduce adverse effects through local drug delivery. Nanotechnology paved the way for targeted delivery through chemotherapeutic and gene delivery systems [15-17]. The biotherapy strategy was also developed to develop targeted drug delivery (A biotherapy is a combination of chemotherapy and phototherapy) . The better treatment method that has been analyzed is biotherapy which is made with the use of nanotechnology-based agents.
Glaucoma is a disorder that causes damage to the optic nerve, where optic nerve carries information from the eye to the brain. It is due to high intraocular pressure and the death of retinal ganglions. Because of this, it causes subclinical inflammation which leads to exfoliation glaucoma, defects in microfibrils which cause a change in biomechanical properties of the surrounding tissue that thereby affects the signals [19, 20]. The nanotechnology-based intraocular pressure (IOP) agents were developed for lowering the intraocular pressure. Timolol and brimonidine lower intraocular pressure. They have increased their property of bioavailability and sustained drug delivery .
MEMS devices were developed to alternate intraocular pressure medication and glaucoma drainage implants . Implanting the MEMS prototype in the sclera and aqueous humor creates a bypass and improves the outflow . Therefore, by controlling the IOP levels the regeneration of damaged neuronal cells and neuroprotection have to be considered for treatment. Thus, microparticles encapsulated girl cells line-derived the neutropenic factor which improves certain limitations [24, 25].
The nanotechnology-induced treatment methods and diagnostic procedures for ocular diseases showed the effective way of their developments in the technology. They have also used MEMS and NEMS strategies for their early detection or diagnosis. The nanoparticle-based medications improved drug delivery systems and management of the biological system. Hence, it made to do the groundwork for promising development of treatment technologies.