How to get the Most out of your Visual Field Testing

Given how important it is to obtain visual field testing and given how it takes both time and effort to do it, it makes sense to do what one can in order to obtain high quality testing. Here I’ll provide some pointers regarding what can be done to ensure that your visual field test is of high quality and value. 

What You Can Do

The quality of visual field testing is dependent upon many factors other than simply the health of the eye^[1]. Of particular importance are things that might impact your awareness and participation.

Get a Good Night’s Rest

As previously mentioned, automated visual field testing is far from exciting. As such, if you are sleep deprived it’s quite possible that you could begin “drifting off” to sleep in which case you will miss seeing the projected stimuli. For this reason it’s critical that you get your rest the night before your visual field test. 

Focus on the Reason You are There

Boring though it may be, while you are taking the visual field test you should be thinking only of the test. Now is not the time to be going over your shopping list or the argument you had with your relative the other night. If you are distracted you will have a tendency to miss the spots of light projected onto the surface in front of you. 

Maintain focus on the Fixation Target

Whenever we see something of interest in our field of vision there is a natural tendency to move our eyes to look at it. However, during visual field testing it is important to resist this natural urge. Keep looking at the fixation target for the best quality test. 

What Your Doctor’s Staff Should be Doing 

Testing Should be Done in a Dark Room

Most visual field testing should be done in a darkened room. This does not mean that the room has to be pitch black, but generally the ceiling lights should be off or dimmed.

Time to Adapt

When moving from an area of high illumination to one of low illumination it takes a few moments for our eyes to adapt to the lower light. This “dark adaptation” tends to take more time for those with glaucoma or elevated intraocular pressure (IOP)^[2]. As such, it is important that you be allowed to adapt to the lower lighting in the testing room for a least a few minutes before beginning the test. 

Silent Room

Whether distractions come from your own thoughts or from sounds outside your head, they both result in decreased attention on the task at hand. As such the room you are in should be quiet. In my practice the visual field testing is done in the same room as our server. The humming of the computer fans provides white noise effectively muting the sounds coming from outside the room. Additionally, we recommend visual field testing be done on days when I’m not also performing eye exams. This limits the number of people in the office, further reducing distracting in-office conversations and noises. 

Correct Refractive Error

If you are a low myope (mildly nearsighted) or younger than 40 years old you will likely not require any lenses to be placed in front of your eye during visual field testing. However, if you are older than 40 years old and/or have a significant refractive error you will need to have a corrective lens placed in front of the eye to be tested^[3] (the other eye should actually be covered by a patch or shield during the test). If you fall into this category and the technician does not place a lens in front of your eye then you should inquire as to why no lens is being used. Don’t assume that all technicians are equally knowledgeable about how to perform visual field testing. 

Provide Instructions

If this is the first time you are taking a visual field test then the doctor’s staff should be providing clear instructions to you. Where are you to look? What are you looking for? What do you do when you see something? What if you need to take a break? How do you pause the testing? When will you know that the testing is complete? 

Ensure Comfortable Positioning

You will be instructed to place your head on a chin rest and against a forehead rest. If you are not comfortable then let the technician know before the test begins. Generally either the chair or table on which the testing unit rests can be adjusted up or down for comfort. If you are uncomfortable that will result in distraction that will negatively impact the quality of the test. 

What Your Doctor Should be Doing 

Reviewing the Test Results

Most likely you will not get the test results immediately after the test is completed. Technicians who are trained to perform the visual field test are not also trained to read the test report. The results of your test will be printed out or electronically transferred to your doctor who will review them prior to when he or she next sees you. At that appointment your doctor should give you an idea of how you did. The amount of detail shared will depend upon whether there has been any change noted as well as on the particular communication style of your doctor. 

References:

[1] Drance SM, Berry V, Hughes A. Studies in the reproducibility of visual field areas in normal and glaucomatous subjects. Can J Ophthalmol. 1966;1(1):14–23

[2] Goldthwaite D, Lakowski R, Drance SM. A study of dark adaptation in ocular hypertensives. Can J Ophthalmol. 1976;11:55–60. http://europepmc.org/abstract/MED/1247940

[3] Weinreb RN, Perlman JP. The effect of refractive correction on automated perimetric thresholds. Am J Ophthalmol. 1986;101(6):706–709

 Related Articles:

1. Visual Field Testing – Why We Do It  
2. Visual Field Testing – What It Is
3. Visual Field Testing – When it Should be Done
4. Visual Field Testing – How It Fits In With Other Glaucoma Testing
5. Physical Activity and Rate of Visual Field Loss