Refractive, in the context of eye care, refers to conditions or errors related to how light is focused by the eye. These errors can result in blurry vision, difficulty focusing, or distorted vision. The most common refractive errors include:

1. Myopia (Nearsightedness): In myopia, distant objects appear blurry, while close objects can be seen clearly. This occurs when the eyeball is too long or the cornea is too curved, causing light rays to focus in front of the retina instead of directly on it.
2. Hyperopia (Farsightedness): Hyperopia causes close objects to appear blurry, while distant objects may be seen clearly. It happens when the eyeball is too short or the cornea is too flat, causing light to focus behind the retina rather than directly on it.
3. Astigmatism: Astigmatism results from an irregularly shaped cornea or lens, causing light rays to focus unevenly on the retina. This can lead to distorted or blurred vision at any distance.
4. Presbyopia: Presbyopia is a condition that occurs with age, typically around the late 30s or early 40s, and affects the ability to focus on close objects. It happens due to a gradual loss of flexibility in the eye's lens, making near tasks like reading or using a smartphone more challenging.

Refractive surgery is a surgical procedure performed to correct the refractive error of the eye. It is usually done to get rid of or reduce dependence on glasses and contact lens . It can be performed in a patient with stable refraction (glass power) after the age of 18 – 21 years. Complete medical history along with detailed eye examination is mandatory in all candidates, special Investigations like corneal topography (Pentacam, Orbscan), Anterior segment Optical Coherence Tomography (ASOCT) are performed to evaluate the shape, thickness and curvature of the cornea and other dimensions of the eye. After acquiring all the details, the eye surgeon (ophthalmologist) makes a decision regarding the available options of refractive surgery for the patient.

The current refractive procedures can be classified as Corneal procedures and Lens based surgery.

Corneal procedures include laser assisted power correction and this can be further divided as 3 types:

1. PRK (Photorefractive Keratectomy) This procedure involves careful removal of the top most layer of the cornea also known as epithelium , this is followed by Excimer laser delivery which reshapes the corneal surface – to correct the refractive power of the eye. A contact lens is placed for a few days to support the healing of the eye, the epithelium is very thin (50 microns) and usually grows back within 3 days.
2. LASIK (Flap Based Procedure) This is a very popular procedure and involves creation of a flap (100-120 micron) in the superficial layer of the cornea. This flap can be created by two methods- by a microkeratome or by a Femtosecond laser. After the flap is created by any of the above two methods, it is lifted and the residual bed is then treated with Excimer laser (same laser used in PRK). At the end of the procedure the flap is reposited back in place, on the corneal bed.
3. Refractive Lenticule Extraction – ReLEX SMILE / FLEX/ SILK This is the most advanced refractive surgery and requires only Femtosecond laser (same laser as described in FEMTO -LASIK). Refractive power of the eye is corrected by using femtosecond laser to create a lenticule (of predetermined size and thickness) within the layers of the cornea. Extraction of this lenticule results in altered shape of the cornea and corrects the refractive power. This surgery does not need Excimer laser, Microkeratome blade or flap hence it is popularly known as blade-less, flap-less refractive surgery.

Lens Based surgeries:
Lens based surgeries involve ‘in the eye -intraocular’ procedures to correct the spectacle power. It can be further divided as

1. Implantable Collamer Lens (ICL): This surgery involves placing an artificial implantable contact lens in front of the natural crystalline lens in the eye. ICL are made of biocompatible material known as collamer (combination of collagen + polymer) and are very different from disposable contact lenses that are used routinely.
2. Refractive lens exchange: In Refractive lens exchange the natural crystalline lens of the eye is removed and is replaced by an artificial intraocular lens (IOL) of the correct power. This procedure extracts the natural lens from the eye using Ultrasonic energy (Phacoemulsification) , hence there is no need for cataract surgery in the future.