EET PG Medical – 2020 – Question – 133
Photostress test to differentiate
a) Lens and cornea
b) The macula and Optic nerve diseases
c) Cataract and glaucoma
d) Retinal and vitreous diseases
Correct Answer – B
Ans:b.The macula and Optic nerve diseases.
>To distinguish optic nerve conduction defects from the macular disease in patients with otherwise unexplained loss of central vision we first determined the best visual acuity with correction at distance in unilateral defects.
> The normal eye was tested first and photo stressed for ten seconds by looking at an ordinary penlight held 2 to 3 cm from the eye.
>The time required to read three letters on three Snellen test lines just larger than the best acuity was used as the endpoint.
>Recovery time will be prolonged with maculopathy.
>Prolonged recovery time will not be observed in patients who have optic nerve disease.
https://www.ncbi.nlm.nih.gov/pubmed/836667
