PSRT is another test used for macular function test. it actually measures the recovery time of photopigments after bleached by a bright light

1. Photo Stress Recovery Time
(PSRT)
Rashad Ibn Muhammed
Assi. Prof Optometry
Ahalia School of Optometry

2. PSRT
• Photostress recovery time is the time taken for visual acuity to return
to normal levels after the retina has been bleached by a bright light
source.
• It is a test of retinal (macular) function and is independent of any
other ocular disease which affect other parts of visual system
• Testing determines the rate of photoreceptor pigment resynthesis by
bleaching the foveal visual pigments
• It cause a temporary state of central scotoma
• Simple test to differentiate between retinal (macular) and post retinal
(optic nerve disease)

3. Macular function
• Long lasting after-images (longer than 15 seconds) produced by
relatively brief flashes of light are due to photochemical changes in
the receptors.
• Light absorption by rhodopsin (it is assumed that cone photo
pigments work in a similar fashion, although slightly faster) leads to
the separation of the retinal chromophore from opsin.
• This process is called bleaching as it results in the loss of rhodopsin’s
purple colour.
• While the photo pigment is being regenerated, the patient will see an
after-image, and it will get active again and show actual image

4. Procedure
• Measure distance visual acuity of both eyes
• Ask the patient to remove their spectacles, but keep them in their lap
so that they can be quickly put back on again.
• 3. Occlude the ‘one’ eye. Hold your direct ophthalmoscope or other
bright light source about 2–3 cm away from the patient’s ‘testing ’
eye. Turn on the light and ask the patient to look directly at the light
for exactly 10 s.

5. Contd
After 10 s, remove the ophthalmoscope, ask the patient to put his or
her glasses back on and point to the letters one line larger than the
patient’s original visual acuity.
• Ask the patient to read those letters as quickly as he or she can after the
after-image has disappeared.
Time how long it takes after removal of the bleaching light for the
patient to read at least 2/3 of the letters on the line indicated.
Repeat the measurement for the ‘other’ eye. assure distance visual
acuity of both eyes

6. Photostress Recovery time procedure

7. Patient will experience like this

8. Recording
• Record the time taken in seconds to recover to within one line of pre-
bleached visual acuity.
Examples:
PSRT: RE 35s, LE 40s
PSRT: OD 45s, OS 105s.

9. Interpretations
• Recovery time is correlated with the other eye
• Normal recovery time is 15-50 seconds
• More than 1.5 min recovery time suggest a macular disease than an
optic nerve related problem
• Time difference between eyes are not more than 5-6 secs

11. Some points to be noted
1. Average recovery-time was between 15 to 50 seconds.
2. Recovery-time increased with age and was more by 3 to 5 seconds in
female.
3. Recovery-time increased with high hypermetropia, high myopia with
degenerative changes, pigmentation macula and yellow spots on the macula.
4. Amblyopic eyes with normal fundus had normal recovery-time.
5. Recovery-time increased beyond 5 minutes in a diseased condition of
macula.
6. Recovery time was within normal limits after cure of the macular disease

12. Common errors
1. Allowing the patient to lose fixation of the
bleaching light.
2. Using a direct ophthalmoscope with batteries
that are not fully charged.
3. Having the patient wait until the letters are
clearly visible rather than just visible.
4. Timing inaccurately.

13. Thank you