Pupil and its abnormalities sept 4 9-2010

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Pupil and its AbnormalitiesOphthaglance 2, Sept 4-5 2010

Dr Anand Sudhalkar, Vadodara


Examination of Pupils

• Involuntary Reflex• Path upto brainstem• Part of general examination, CNS,

Ophthalmology


Types

• Pupillary Light Reflex (PLR)• Convergence and accommodation reflex


BasicsPupillary light reflex

1. Four neuron arc

2. Retina to Pretectal nucleus

3. Internuncial neurons) connects each pretectal nucleus to both Edinger-Westphal nuclei

4. Edinger-Westphal nucleus to the ciliary ganglion.

5. The fourth neuron leaves the ciliary ganglion and innervates the sphincter muscle


OCULOSYMPATHETIC NERVE PATHWAY TO THE EYE1. Three neuron arc.

2. First neuron (Preganglionic) starts in the posterior hypothalamus and terminates in the ciliospinal center of Budge

3. The second neuron (Preganglionic) passes to the superior cervical ganglion

4. The third neuron (Postganglionic) joins the ophthalmic division of the trigeminal nerve to reach the ciliary body and the pupil dilator muscle via the nasociliary and long ciliary nerves.


Examination Methods: Ophthalmic

• Cover/Uncover test- Galen: 2nd century• Swinging light test: Levatin P. Pupillary escape in disease of the retina or

optic nerve. Arch Ophthalmol 1959; 62: 768–779.

• Thompson HS, Corbett JJ, Cox TA. How to measure the relative afferent pupillary defect. Surv Ophthalmol 1981; 26: 39–42.

• Pupil Cycle time (PCT): Stern H.J. 1944 . A simple

method for the early diagnosis of abnormality of the pupillary reaction. Br J Ophthalmol 1944; 28: 275–276.

• Infrared Video Pupillograghy (IVP): 1958 Lowenstein O, Loewenfeld IE. Electronic pupillography: a new instrument and some clinical applications.

Arch Ophthalmol 1958; 59: 352–363.• Pupil Perimetry: Harms 1949


Requirements

1. Semidarkened room.

2. Light should NOT be shined directly into the patient's eye. The light source should be directed from slightly inferior and upward toward the patient's pupil

3. Viewing a distant object: This prevents both accommodative and convergence from coming into play.

4. It is important that both direct and consensual reflexes be assessed.

5. If the afferent arc is intact the direct response should be equal to the consensual reflex.

6. In anisocoria the pupils should be reassessed in varying illumination. anisocoria that varies with illumination has pathological significance


Swinging Light test

Advantages

• Simple to perform, needs a torch light only

• Quantification possible with varying intensity and exposure time

• Use of NDF and detecting RAPD possible.

Falacies

• Unequal retinal blanching, “Off” axis stimulation in strabismus

• Induction of accommodative reflex

• Anisocoria, • Natural variation of 3db in

pupillomotor drive• Media opacity• Bilateral pathology


Afferent Pupillary Defect (APD) "Marcus Gunn" :

1. Normaly, both pupils constrict equally when either eye is stimulated.

2. Direct reflex:

3. The affected eye: constricts less and re-dilates more than a normal eye or (fellow eye).

4. The normal eye: greater direct response than consensual; consensual reflex:

5. The affected eye has a greater consensualcoming from the normal eye than direct.

6. Pupillary escape. The abnormal eyes pupillary reaction is more sluggish than the normal eye, therefore, when the light stimulus is brought from the normal eye to the abnormal eye the affected pupil dilates instead of constrict.

7. This occurs because withdrawing of the light from the normal eye outweighs the constriction produced by the abnormal eye.


Pupil Cycle Time (PCT)

• Focus small 0.5mm slitlamp beam at pupillary margin

• Constriction of pupil cuts off the light entering the eye and pupil dilates, the cycle goes on

• Time the oscillations to the count of 30 with a stopwatch.

• Does not require fellow eye comparison• Influenced by resting pupil diameter and disease

in efferent pathway, autonomic dysfunction.


Exceptions in Pupil/vision relationship

• Pupil Sparing: • Pupils react normally with vision loss in

hereditary optic atrophy (Leber’s)• Vision sparing: • Pupils continue to react sluggishly after

recovery of vision in optic neuritis.


Argyll Robertson Pupil (ARP):

Hallmark of neurosyphilis.

1. Light-near dissociation (no reaction to light but brisk response to near).

2. Both pupils usually involved, but the degree may be asymmetrical.

3. Pupils are small and frequently irregular in shape.

4. Pupils dilate poorly after instillation of mydriatics.

5. To make a diagnosis of ARP vision in the affected eye must be normal.


Adie's (Tonic) Pupil:1. Typically in women in their third to fourth decade of life. women:men ratio 3:1

2. Unilateral in 80% of cases;

3. There is no response to either direct or consensual light reflex.

4. Cause: The lesion is in the ciliary ganglion: Denervation of the postganglionic nerve supply to the sphincter and ciliary muscle (pupils and accommodation are affected). Internal ophthalmoplegia with loss of sphincter and accommodation; with the accommodation being very sluggish

5. Affected pupil relatively dilated in bright light and relatively constricted in dim.

6. 0.125% pilocarpine 1 gtt placed in both eyes will cause the Adie's pupil to constrict, because of denervation and hypersensitivity, whereas the normal pupil will not be affected by such a low concentration.

7. There is a reduction in the knee jerk reflex in a number of these patients.

8. It is a benign condition; with time the accommodative response improves while the tonicity of the light response gets worse. There is no treatment and patient reassurance is important.


Horner's Syndrome.

1. Miosis, which is always present in this syndrome; the anisocoria is more marked in dim illumination.

2. Moderate Ptosis - paralysis of Müller's muscle

3. Pupillary responses to light and near are unimpaired.

4. Decreased sweating (anhydrosis) on the ipsilateral side of the face.

5. Increased accommodation secondary to unopposed action of the parasympathetic.

6. Heterochromia of the iris may be present If the lesion occurred during early infancy or congenitally.

7. The prognosis is much better if the causative lesion is postganglionic than if preganglionic.

8. Test: 1% hydroxyamphetamine (Paradrine®) instilled in both eyes will cause a

a) preganglionic lesion pupil to dilate; (. Lesions located in the central (brainstem or spinal cord) or preganglionic (chest or neck) will cause the pupil to dilate. The most common cause being malignant tumors of the lung usually of the upper lobes (Pancoast's tumor), which place pressure on the cervical sympathetic trunks

b) postganglionically located lesion will not dilate. Remember Horner's pupil is miotic (small). This drug can be relied on to dilate the Horner's (preganglionic lesions) pupil and a normal pupil with the sympathetic pathway to the eye intact. The dilation will be reduced or absent in patients with postganglionic lesions.Hydroxyamphetamine (Paradrine®) test in a Horner's patient. With 1 gtt of 1% OU there is dilation of the normal right eye and none in Horner's syndrome.


Common Ophth Causes

• 1.) Central Retinal Artery occlusion (CRAO)2.) Central Retinal Vein occlusion (CRVO)3.) Optic Atrophy4.) Marked retinal detachment5.) Anterior Ischemic Optic Neuropathy (AION)6.) Branch Retinal Vein Occlusion (BRVO)7.) Asymmetric Primary Open Angle Glaucoma (POAG)


Diagnostic Importance

• Retrobulbar neuritis• Severe retinal Pathologies• Malingering and Amblyopia• CNS disorders

Health & Medicine

Pupil and its abnormalities sept 4 9-2010