A-Scan is used for lens power calculation before cataract surgery and is performed in all patients undergoing this surgery at Eye Solutions in Mumbai. A-scan ultrasound biometry, commonly referred to as an A-scan, is a diagnostic test used by ophthalmologists. It provides data on the eye length for the calculation of intraocular lens power.
When cataract surgery is performed, the natural lens in the eye is removed and replaced with an artificial lens (IOL). Regardless of the type of lens used, Standard IOLs or Premium IOLs, measurements of the eye are needed before surgery. Here, most patients ask us which is the best lens and more can be read about that.
These measurements are highly precise. When combined with special computerized calculations, these allow the surgeon to choose the power of intraocular lens which is appropriate for each eye. Because each eye has a different size and shape, the power in the lens needed is different for each eye. For this reason, an A-Scan is always required prior to cataract surgery.
These days cataract surgery is not only a surgery to get rid of the cataract. Over the years it has gradually become like a refractive surgery. In other words, apart from removing the cataract, ophthalmologists also want to leave the patient glass free. Thus, ophthalmologists need to calculate the lens power with a high level of accuracy. An A-scan in Mumbai is available with most ophthalmologists and also at Eye Solutions.
Different machines can throw out different kind of reports. However, what these machines calculate remains the same. Here is a copy of one of our reports. The section on the top shows the various measurements.
Then this information is fed into a formula to calculate the lens power. Every hospital has their lens choices that they commonly use. Each lens has what is known as an A contstant. This A constant is entered in that formula and based on the A constants that have been entered in the machine the report shows various lens options and their powers. In this report you will see calculations for Monofocal lenses of different companies. The top right is for Technis IOL. This same chart is used for the Eyhance lens and the Technis multifocal lens.
Usually a good A Scan machine or what is known as a Biometer is enough. However, there can be certain situations where we may perform an additional test. These additional tests can be performed if your cornea is highly curved or has astigmatism. These tests could be Corneal Topography or Aberrometry. The results of these tests aid in determining the lens power along with the findings of the scan.
No. All you have to do is place your chin on the chin rest of the instrument and a picture is taken which takes less than 10 seconds per eye. Sometimes the eye is numbed with eye drops and the probe is used to touch the eyes. Because of the numbing eye drops one does not feel anything.
The entire procedure takes not more than 5 minutes.
Watch the video below to understand how quick it is.