Vision Test and check up of glass power

This is done with a Snellen eye chart, which has several rows of progressively smaller characters in form of letters, or numbers or shapes and pictures. The test supervisor determines the line with the smallest characters, which the patient can read correctly. Visual acuity is expressed as the ratio of the distance from the chart at which a person reading the chart is able to read characters in that line correctly, compared to the distance at which a normal sighted person could correctly read the same line.

For example, a determination of a visual acuity of 20/50 means that what the person, reading the chart, can see at 20 feet could be seen by a normally sighted person at 50 feet.

Normal vision is 20/20. It means one person can read line marked 20 from 20 feet distance. In metric system it is read 6/6, wherein the distance 6 is 6 meters.

If any defect in vision is found, corrective lenses are placed in front of eye after retinoscopy. You are then asked to read the chart again. Although the characters may appear blurred at first, fine adjustment of lenses by the doctor will make it clear. After checking your distance vision Doctor will check for your near vision and necessary correction will be done. Normally the same can be done in one day but occasionally Doctor may like to put drops in your eyes, especially in children, to check the power thus requiring 2 sittings.

Slit Lamp

Computerized Refraction

In place of retinoscope nowadays we use computer to get the approximate refractive error known as computerized refraction . Putting lenses in front of eye is again done for final check up. This can be done by paramedical personnel and saves time for the surgeon. 

Slit Lamp examination

 It is a microscope that magnifies and illuminates the surfaces of cornea, iris, lens and anterior chamber to locate the defects in them.

Intraocular Pressure measurement

If the pressure of eye is high, it can lead to irreversible blindness. The disease is known as Glaucoma. The eye pressure is measured by tonometer. This instrument painlessly presses over the eye to check the pressure. The test is important particularly for persons above 40 years as this is the time normally Glaucoma occurs.

Indirect ophthalmoscope with lenses

Ophthalmoscope

This magnifies and illuminates the deeper structures of the eye and allows the doctor to examine the retina for possible problems. Retina is the only part in the body where nerves and blood vessels are directly visible. We can detect signs of many diseases such as Diabetes and hypertension.