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VISUAL FIELD TESTING

INTRODUCTION

Did you know about visual field testing? If you don’t then this blog is a perfect source of information to read. As you can focus on the word ‘visual testing’, can you imagine how much can you see from the corners of your eyes? Can you observe what's happening in your surroundings? 

Your visual testing is about how much wide area your eye can see? When you are focusing on a central point? Vision field testing is the test in which an ophthalmologist can measure vision in each of the eyes. He also measures how much vision loss has occurred over time. 

VISUAL FIELD TESTING DETECT BLIND SPOTS

Scotoma is a blind spot in the vision of your eyes. Visual field test identifies if you have a blind spot and what place they are in your vision. Scotomas size & disease in the test will explain how much eye disease & brain disorder is affecting your vision. 

Visual field test also tells how much vision is limited by eyelid problems, like ptosis & droppy eyes (Links to an external site.). 

TYPES OF VISUAL FIELD TESTING 

There are 6 types of visual field testing

  1. CONFRONTATION VISUAL FIELD TEST

It is a very common test where the patient looks directly into the eyes/nose of the doctor. Then doctor checks each quadrant in the patient's visual field and asks to count the number of fingers that doctor is showing on the peripheral side. The test is for both of your eyes independently. 

The normal visual field can reach 180 degrees in the horizontal plane, and 135 degrees in the vertical plane. So when the patient is seeing a moving target it should start from the outside 180 degrees visual. 

  1. AUTOMATED STATIC PERIMETRY TEST

An automated static permanent test is suggested by an eye doctor to check any eye problem or to monitor the progress of your eye disease. It is a very popular technique to know if a patient has glaucoma and neuro-ophthalmic conditions. Ok but your opthalmologist will take extra tests for the sake of eye care (Links to an external site.). He will rely on more tests to deduct results about how you see objects inside the field of vision. 

This test starts with seeing inside a bowl-shaped instrument called a Perimeter. One eye will be covered. You will be asked to look straight inside the center target through the test. Very small & dim lights will start to appear in different places inside the bowl. And you will be asked to press the button every time you see those lights and the Perimeter machine will track which light you miss.

You are allowed to blink during the test. You can also take a break if you need like.

  1. KINETIC VISUAL FIELD TEST

Kinetic visual field tests include moving objects in & out of the peripheral's vision. This test will help find out the edge of the patient's field of vision. It is quite similar to the Perimeter testing process with one difference, instead of blinking light this uses moving light targets. FREQUENCY DOUBLING PERIMETRY

There's one more way your opthalmologist can guess the loss of vision. He uses a portable called Frequency Doubling Technology (FDT) perimeter. The test uses optical illusion to check if there's any damage in the vision. It has bars that flicker at varying rates. Did you know how an opthalmologist can perceive if you have any vision loss? It's like you won't be able to see verticle lines at certain times. 

It is an inexpensive gadget that is designed for fast & effective detection of the visual field loss. 

  1. ELECTRORETINOGRAPHY
  2. AMSLER GRID: A BASIC VISUAL FIELD TEST FOR CENTRAL VISION