Recent years have witnessed the emergence of biosensing ophthalmic lenses, a groundbreaking concept that extends far beyond conventional refractive correction. These lenses integrate biotechnology and nanotechnology to function simultaneously as diagnostic and therapeutic tools.<br />The principle relies on embedding nanoscale sensors within the lens material, capable of detecting biochemical markers in tear fluid, such as glucose, lactate, and inflammatory proteins. Such technology could provide a non-invasive method of monitoring systemic conditions like diabetes or detecting ocular diseases at an early stage.<br />Beyond diagnostics, biosensing lenses can also incorporate controlled drug delivery systems. These systems enable the release of precise amounts of medications (e.g., antibiotics or anti-glaucoma agents) directly onto the ocular surface, increasing therapeutic efficacy while reducing side effects compared to traditional eye drops.<br />The major barriers to clinical application include maintaining optical transparency despite electronic integration, ensuring biocompatibility, and developing safe and sustainable power sources. Current research explores flexible bio-batteries and harvesting energy from eyelid motion as potential solutions.<br />Biosensing lenses symbolize a fusion of ophthalmology, biotechnology, and biomedical engineering. They hold immense potential to redefine personalized ocular care, moving from corrective optics to intelligent systems capable of diagnosis, monitoring, and targeted therapy.<br />