Today, cataract surgery is not simply about removing the cataract from eye and replacing it with an IOL (Intra Ocular Lenses). A lot depends on a near perfect IOL power calculation. The vision can therefore be customized to suit your requirement i.e. distance dominant, near dominant or intermediate. There are two ways to calculate the IOL power
The Ultrasound method
Here an ultrasound machine called an A scan is used. The eye is numbed with anesthetic eye drops and the ultrasound probe in a water shell is brought in close approximation to the eye (immersion technique). The moment the probe is in the right position, 10 rapid readings are taken in quick succession. The best reading is picked up for calculations.
The Optical method
Here an optical biometer like the lenstar is used. A diode laser light is passed into the eye, and the reflection echo are noted by a special sensor. The time taken to record the reflected echo is interpreted as the axial length of the eye which determines the IOL power calculation. This technique is highly accurate, and is considered the gold standard for IOL power calculation. Both the above methods are used in our major centers to cross check the calculations. (corrections for this page by web designer : the first picture will be replaced by the ultrasound machine and underneath write ‘Ultrasound A Scan’. Under the second picture write ‘Optical biometer – Lenstar).