Middle Layer , Accomodation , Horners

Question 1

Thickest Nd thinnest part of iris

Answer 1

Thickest is colarette ( junction between pupillary and ciliary zone)

Thinnest is root of iris

Question 2

Nerve supply of sphincter and dilator pupillae

Answer 2

Sphincter pupillary—. Parasympathetic c.n. 3,7,9,10 ( cn 3 occulomaror nerve inferior branch which also supplies inferior oblique)
Short Ciliary nerve

Dilator pupillae— sympathetic
Long ciliary nerve

Question 3

Pancoast tumour lead to horners syndrome

Answer 3

Pancoast tumour is the tumour of parenchyma of the lung so while resection of tumour because sympathetic fibres are crossing anteriorly from c8- t1 (spinal chord) to the superior cervical ganglion ( in neck)
Sympathetic fibres also get cut leading to horner’s syndrome

From superior cervical ganglion fires travel - up along internal carotid artery and via long ciliary nerve supply dilator pupil— ciliospinal reflex

Question 4

5 features of horners

Answer 4

HI MAPLE
Hetrochromia IRIDIS
Inferior eyelid elevated 
Miosis
Anhydrosis ( ipsilateral absence of sweating)
Ptosis
Loss of ciliospinal reflex
Enopthalmos- sunken eyeball

Question 5

Diagnosis of horners syndrome

Answer 5

4% cocaine test
Pupil doesnot dilate on instillation(horners pupil)

To find out site of lesion
Amphetamine/ adrenaline test
Horners pupil dilate -1 nd 2 order neuron lesion( preganglionic )
Doesn’t dilate - 3 rd order neuron lesion ( postganglionic lesion )

Question 6

Causes of miosis and mydriasis

Answer 6

Miosis -HI COPS
Horners
Iridiocyclitis
Clonidine carbolic acid
Opc opoids( morphine)
Parasympathomimetics phentolamine pilocarpine
Sleep sedatives 

Mydriasis - BIG OATS
Belladona poisoning
Internal opthalmoplegia
 Glaucoma
Occulomotor nv palsy
Atropine
Tonic pupil
Sympathomimetics

Question 7

Changes during accommodation

Answer 7

Ciliary muscle contract 
Zonules relax
Anterior curvature increases
Posterior curvature won’t change
AP diameter of lens increases

Question 8

Anomality in accommodation is

Answer 8

Problem in near vision so high power lens needed ie convex lens (+)
Every 5 year the power increase by +0.5
45 year +1 D
50 +1.5 D

Question 9

Spasm of accommodation

Answer 9

Ciliary muscle become permanently contracted causing problem in far vision
Mimics myopia
permanent accommodation.
Treatment cycloplegics ( temporary paralysis of ciliary muscles pharmacologically)—atropine