Inside of that is the pupil which we can see change its shape depending on the brightness of ambient light. It becomes small in size, constricts, when the light is bright and becomes larger in size, dilated, when light is dim. A pupil is like the aperture of the camera. A pupil is the central opening in Iris. It’s the color of Iris that gives color to our eyes. In darkers races like Asians, Indians and african races the iris has a lot of pigments, hence eye color is dark while in fairer races Iris lacks pigments making them appear grey, green or blue. Certain autoimmune or infectious diseases can cause inflammation of Iris leading to redness, pain, photophobia and is known as iridocyclitis.
The lens of the eye is behind the iris. It also helps in focusing the light onto the film of the eye, the retina. The lens is held in suspended position behind the iris by thin fibres known as zonules. It makes it possible for lens to change its shape because of these zonules,this inturn makes it possible for the eye to work as auto focus camera and focus at different distances. This autofocus mechanism is known as accommodation. Accommodation starts becoming weak after age of 40 and that’s when one requires glasses to look at near objects. This is a natural process and is known as presbyopia. In young individuals the lens of the eye is completely transparent, however as one grows older, this transparency progressively reduces and it becomes opaque. This is known as Cataract. As the cataract becomes more and more opaque patients vision progressively reduces. When it reaches a point where she is unable to do daily activities, cataract surgery with intraocular lens implantation is done. In olden days when techniques and technology for cataract surgery was primitive, doctors used to wait for Cataract to mature. However with improvements in technology and surgical techniques, surgery can be done when a patient feels the need and need not be postponed till complete blindness has developed. A patient who is homebound and has limited visual needs may choose to wait a lot longer than someone who leads an active lifestyle and even minimal visual disturbance hampers daily life.