|Year : 1971 | Volume
| Issue : 3 | Page : 93-101
Macular function tests with special reference to photostress test
SRK Malik, Gurbax Singh, GC Sood, AN Gupta
Maulana Azad Medical College, New Delhi, India
Maulana Azad Medical College, New Delhi
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Malik S, Singh G, Sood G C, Gupta A N. Macular function tests with special reference to photostress test. Indian J Ophthalmol 1971;19:93-101
|How to cite this URL:|
Malik S, Singh G, Sood G C, Gupta A N. Macular function tests with special reference to photostress test. Indian J Ophthalmol [serial online] 1971 [cited 2020 Aug 5];19:93-101. Available from: http://www.ijo.in/text.asp?1971/19/3/93/34983
The functional condition of the macula is examined objectively by means of an ophthalmoscope and subjectively by recording the visual acuity but these do not give an exact idea about the functional status of the mcaula.
Photostress test was introduced by Bailliart (1954) who dazzled the macula with the light of an ordinary ophthalmoscope and measured recovery time of central vision. The basis of the test is to utilise an induced fatigue of the macula analogous to the induced fatigue utilised for the examination of the heart.
Other workers have also utilised this test in the investigation of cases of macular diseases. (Chilaris and Pountza; Drauault - Toufesco, Magder, Chilaris, and Forsius, Eriskson and Krause).
This study was undertaken to evaluate the various macular function tests with special reference to the photostress test.
| Methods and Materials|| |
60 normal cases (equal number of males and females) and 20 cases of macular and optic nerve pathology were taken from the ophthalmic O.P.D. of the Irwin Hospital New Delhi for this study.
The following tests were carried out:
(i) Visual acuity, (ii) Colour vision,
(iii) Ophthalmoscopic examination,
(iv) Amsler charting,
(v) Haidinger Brushes on the Clement Clarke synoptophore,
(vi) Photostress test (Dazzling test),
Methods of Dazzling the Macula:
The patient was seated in a semi dark room. Corrected visual acuity was recorded. The macula of the eye under study was dazzled with an electric ophthalmoscope (oculus) 15 mm from the anterior surface of the cornea for varying time period and further exposure's were given only after complete recovery from the first exposure. The other eye was kept covered.
The photostress test was done in the following groups:
In normal cases
(a) With undilated pupil 120 eyes (60 cases).
(b) With dilated pupil 52 eyes (26 cases).
Cases of macular and optic nerve pathology 20 cases.
| Observations|| |
The observations were recorded in two groups mentioned above [Table - 1],[Table - 2],[Table - 3],[Table - 4],[Table - 5],[Table - 6],[Table - 7],[Table - 8],[Table - 9].
Ideal Plashing time: The recovery time varies with the period of exposure i.e. 0 to 50 seconds in 5 to 25 seconds exposure, 11 to 51 seconds in 30 seconds exposure. When the exposure time was more than 30 seconds, the recovery time was 11 to 71 seconds. In one third of such cases, the time of recovery was more than 60 seconds. The ideal dazzling time was found out to be 30 seconds.
Effect of Age and Sex on Dazzling test: The recovery time tends to be more in females than males between 20 to 50 years of age by 5 to 8 seconds while in extremes of age there was no significant difference. Average recovery time tends to increase with the age of the patient [Table - 2].
Effect of size of Pupil on Dazzling test: It has no effect on the recovery time of macular functions [Table - 3].
Effect of Flashing of one eye over the Recovery time of other eye: Flashing of one eye has no effect on the recovery time of the second eye which has been dazzled previously.
The observations were recorded separately for various diseases [Table - 4],[Table - 5],[Table - 6],[Table - 7],[Table - 8].
(i) Central serous retinopathy (CSR) (9 cases): In 8 cases the photostress time varied from two minutes 30 seconds to 25 minutes while in one case No, 8 (a, b) the test was within normal limits. Out of 8 cases 7 cases showed defects on Amsler Charts which recovered to normal much earlier than photostress test. Cases No. 8 (a, b), who had normal photostress time but showed translucid scotoma on Amsler Chart, defective vision and active oedema, did not show any improvement during three months follow up.
It was also obvious that photostress tune was prolonged in active stage of the diseases. It started coining to normal as the stippling in the fundus appeared. The photostress time returns to normal a long time after the cessation of disease process as revealed by other macular function tests. Once the photostress time recovered within normal values, further improvement of visual acuity did not occur.
(ii) Macular oedema due to causes other than central serous retinopathy (C. S. R.): Total of 8 cases were studied. The photostress time in one case of iridocyclitis with macular oedema was 5 minutes and 20 seconds, in 3 cases of central haemmorhage was 4 minutes 30 seconds to 7 minutes 20 seconds; and in one case of aphakic detachment with macular involvement was 1 minute and 10 seconds. Amsler charts showed a translucid scotoma in all the 7 cases. Haidinger brushes were not perceived in one case (No. 13) of detachment of the retina. Colour vision was normal in all these cases. In two cases of traumatic oedema, only case No, 14 showed prolonged photostress time while case No 15 had normal photostress time. The cases with normal photostress time did not show any functional recovery but in the other the recovery was good.
(iii) Macular degeneration due to C.S.R.: [Table - 7] In 4 cases the photostress time ranged from 13 seconds to 1 minute and 35 seconds. The cases where dazzling test was more than a minute showed improvement in subsequent follow up. The other macular function tests were normal.
(iv) Macular degeneration due to causes other than C.S.R.- In four cases, the photostress time varied from 1½ minutes to 2¾ minutes. In these cases other tests were normal except funds examination which showed senile macular degeneration.
(v) In optic nerve diseases: In one case of retrobulbar neuritis and an other of optic nerve sheath haemmorhage the photostress time was 30 seconds and 4-5 seconds respectively. Amsler chart showed a paracentral translucid scotorua in both these cases while the other macular function tests were normal.
| Discussion|| |
It is a known fact that the appearance of the macula examined with an ophthalmoscope may not give a true picture about its functional status. It is also fairly difficult to predict prognosis in macular diseases on the basis of ophthalmoscopic findings. The study was undertaken to find cut a suitable way to assess the functional status which may also help in prognosis.
120 normal eyes who had normal colour values and appreciated Haidinger- brushes normally were investigated for photostress test. Ideal time for dazzling of the macula was found to be 30 second. If the macula was dazzled for more than 30 seconds, it took much longer time for recovery besides being uncomfortable to the patient. Moreover it did not give any added advantage of unmasking any other information. Where a stimulus was given for a period less than 30 seconds it did not show a latent period which was probably due to inadequate exposure and hence had no value in the diagnosis or the prognosis of the cases. The recovery time varied from 10 to 60 seconds. Any valve above 60 seconds was regarded as pathological. These values were, though not statistically significant, were slightly higher in females than males between 21-60 years and sere equal in extremes of ages. The size of pupil did not have any influence on the photostress time. The observations for normal individuals are identical with the findings of Magder, Chilaris, and ForSius et al.
In all the cases of central serous retinopathy, the photostress time was prolonged from 2½ minutes to 25 minutes though the colour vision and appreciation of Haidinger brushes were normal. Translucid scotomas were demonstrated in all cases on Amsler chart in early stages. The recovery time came to normal much later than the disappearance of sctoma on Amsler chart. Once the recovery time came to normal, further improvement in the visual acuity did not occur.
Improvement of vision to the normal on Snellen Chart is not a true indication of the total functional recovery of the macula. 5 patients who had normal visual acuity of 6/6 with prolonged photostress time were not satisfied subjectively.
Druault - Toufescp ; Magder  Chilaris  and Forsius and Erikson  also found a prolonged recovery time in cases of C.S.R., but they did not correlate with the other macular function tests. They did not attach importance of this test in the prognosis of C.S.R. cases. In case No. 15 who was suffering from active macular oedema but showed a normal photostress time did not show improvement -in the visual acuity inspite of treatment, while another case (No. 14) of traumatic macular recovery after treatment. The cases were followed up for 3-6 months. This is useful information in the prognosis of the disease i.e. if the lesion is associated with normal photostress time, there is little chance of further improvement in visual function but if associated with a prolonged photostress time. there exists every possibility of visual recovery.
The photostress time was also prolonged in cases of senile macular degenerations and detachment of the retina. This finding is in agreement with the observations of other workers - Magder; Chilaris.
In 2 cases of optic nerve disease (one of optic neuritis and optic nerve sheath haemmorhage) where visual acuity was grossly disturbed with central scotoma on Amsler, chart, the photostress time was normal. The photostress time is not affected in these conditions as the test depends upon the degradation and regeneration of cone pigment, change of pH of the fluid between the cone processes and the pigment epithelium and the contact of the cones with the pigment epithelium. some workers Lange and Simon  and Magitot  found in experiment on carp isolated retina, that retinal pH changes to the acidic side by production of phosphoric acid under the influence of light, while in darkness it becomes neutral or slightly alkaline. If there is no permanent separation of cones from the pigment epithelium, the photostress time will remain normal.
| Summary and Conclusions|| |
(i) The photostress time in 120 normal eyes (60 cases) of both sexes was 10 to 60 seconds and a value above 60 seconds was taken as abnormal.
(ii) The photostress test is independent of the size of the pupil. (iii) It is more in females by 5 to 8 seconds than in males between 20 to 60 year of age group.
(iv) The photostress time increases with increase in the age of the individual.
(v) The photostress time was prolonged in active cases of C.S.R. It ranged from 2½ to 25 minutes.
(vi) The photostress time returned to normal a long time after the other macular function tests showed normalisation.
(vii) Once the photostress time normalises, further improvement in visual acuity did not occur.
| References|| |
BAILLIART, J. (1964) Soc. Ophthal. Paris. 2, 350.
Idem (1941) Ann. Ocul. 177, 355.
CHILARIS, G. and POUNTZAS, D. (1955), Arch. Ophth. Soc. N. Greece 4, 134.
CHILARIS, G. (1962) Amer. J. Ophth. 53, 311.
DRUAULT TOUFESCO, M. (1957) Bull. Soc. France, Ophthal. 70, 194.
FORSIOS, H. KRAUSE, V. and ERIKSON, A. (1963) Afta. Ophth. 4, 25-32.
FORSIUS, H.; KRAUSE, V. and ERIKSON, A. (1964) Acta Ophth. (Kbh) Vol. 42 No. I, 35.
FORSIUS, H. ERIKSON, A. W. and KRAUSE, V.; (1964) Acta Ophtha. (Kbh) Vol. 42, No. I, 25-35.
LANCE AND SIMON (1921) Ztschif, Physioli, Chem. 120, 1.
MAGITOT, A. (1946) Chemi. Eye Physiology, Paris, Mason.
MAGDER, H. (1960) Am. J. Ophth. 49, 147.
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5], [Table - 6], [Table - 7], [Table - 8], [Table - 9]