Disorders of Visual Pathway and Pupillary Reflexes MCQs

An isolated dilated pupil that reacts to near better than light is typically from a tonic(Adie) pupil. Loss of accommodation frequently occurs with pupillary dilation. Accommodative insufficiency and accommodative spasm are not associated with pupillary dilation. Third nerve palsy would be expected to have other features, including ptosis and an ocular misalignment. In Adie's Tonic Pupil, the affected pupil is larger(anisocoria). Its exact cause is not known. It is usually unilateral, associated with absent knee jerk and occurs more often in young women. Adie's pupil constricts with weak pilocarpine(0.125%) drops, while normal pupil does not. Reference: A.K.Khurana, 5th Edition, Pg: 293.

Ans. C. Retrobulbar neuritis Swinging flash light is used for relative efferent pathway defect (RAPD) which is most characteristic of Iesions in the optic nerve. Thus it is positive in retrobulbar neuritis.

The findings suggest a problem with the pupillary sphincter(greater anisocoria in light). Normal lid position, alignment and eyelid position make third nerve palsy unlikely. Cocaine is useful in the diagnosis of Horner syndrome. Slit-lamp biomicroscopy would be the most helpful to distinguish abnormalities in the iris that might suggest a tonic pupil or trauma as the cause of anisocoria. Reference: A.K.Khurana, 5th Edition, Pg: 293, Parsons, 22nd, Edition, Pg: 33.

It is about a normal individual’s visual acuity. If he reads 6/6, at 36 mtr he should be able to read 6/36 line. Reference: Khurana Optics 2/e

Concussion injuries to the brain These are usually associated with subdural hemorrhage and unconsciousness which may produce the following ocular signs. Hutchinson's pupil: It is characterised by initial ipsilateral miosis followed by dilatation with no light reflex due to raised intracranial pressure. If the pressure rises still further, similar changes occur in the contralateral pupil. Therefore, presence of bilateral fixed and dilated pupils is an indication of immediate cerebral decompression. Papilledema: When it appears within 48 hours of the trauma, it indicates extra or intracerebral hemorrhage and is an indication for immediate surgical measures. While the papilledema appearing after a week of head injury is usually due to cerebral oedema. Reference: AK Khurana, 5th Edition, Pg: 311.

It is an anastomoses of long PCA and ACA at the root of the iris From it several branches arise to reach ciliary process. One goes to pupillary margin and forms minor arterial circle Reference: Khurana 8 ed, page 141

Explanation: It is an anastomosis of long PCA and ACA at the root of the iris From it several branches arise to reach ciliary process. One goes to pupillary margin and forms minor arterial circle

The primary visual area(Area no 17) is located in the Calcarine sulcus in the Occipital lobe of the brain. The accessory visual areas are Area 18 and Area 19. Reference: Yanoff and Duker, 4th edition, Pg: 910-911.