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Photostress test: testing is done monocularly. Slight changes in theretinal pigment epithelium (RPE), choroid, choriocapillaris and outer

retinal layers can result in reduced acuities. One of the complaints apatient may present with is difficulty with night vision. Examples, small

serous detachments of the RPE or retina and macular degeneration.

These conditions are not always easy to determine nor to what extenta patient's visual acuity will be reduced when viewed

ophthalmoscopically.

The photostress test is a very simple test to run and is intended to

differentiate between optic nerve and macular (retinal) problems.There is a difference in the recovery time for those patients over 40

years of age and younger patients. The acceptable recovery times of50 to 60 seconds are more in line with patients over 40 years.

Recovery time for young healthy individuals with no macular problems

can be markedly less.The test should always be run before either Goldmann tonometry or

dilation. Specifically patients having reduced vision in one eye thatcannot be explained nor improve with the use of a pinhole. The

patient's best correction is first determined and their acuities aremeasured monocularly. The patient is asked to cover or occlude the

eye with the worst vision while the good eye is subjected to a bright

light from your ophthalmoscope directed onto the macula for 10seconds. Some authors feel having the patient look at a bright penlight

or transilluminator will cause adequate bleaching of the retina. Theproblem with this technique is you cannot be sure the patient is

looking directly at the light with their macula foveal area. With thepatient wearing their best correction they are asked to read backwardsthe line of letters just above their best line of acuity. The projector and

acuity chart should already be set up containing the line of best acuityand the line just above. The timing starts when the ophthalmoscope or

penlight is removed. Photostress recovery time (PSRT) is the time it

takes for the patient to read the line just above its pre-test best acuityline backwards. The same procedure is then repeated for the fellow

eye.Patients with normal healthy macular function should be able to read

the line in 50 to 60 seconds. Patients with a macular problem mayhave recovery times lasting 1.5 to 3 minutes or longer. Those patientswith visual acuities of 20/80 or worse are not good subjects for this

test.If the cause for the reduce visual acuity is optic nerve, the bleaching of

the retina will have no effect on the recovery time. Recovery time willbe normally 50 to 60 seconds or basically equal for both eyes.

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