Third Year b. Pharm (semester-VI) Practical experiment no-16

1. Study of Mydriatic and Miotic
effects on rabbit eye.
Dr. Sameer H. Sawant,
Assistant Professor Pharmacology,
Experiment No. 15
Pharmacology-III Practical
B.Pharm Semester-VI
Dr. Sameer H. Sawant, Pharmacology, SIOP 1

2. • Aim: Study of Mydriatic and Miotic effects on rabbit eye.
• References:
1. Kulkarni S K. 2010, “Hand book of experimental pharmacology”. Vallabh Prakashan, Delhi, 3rd edition, Pg.
Nos. -153-155.
2. Badyal D. 2018, “Practical manual of Pharmacology”. Jaypee brothers medical publishers, 2nd edition, Pg.
Nos.- 71
Dr. Sameer H. Sawant, Pharmacology, SIOP 2

3. Requirements:
1. Animal: Rabbits weighing about 2-5 kg
2. Drugs: Mydriatics drug- Atropine (1% W/V), Phenylephrine (20%
W/V),
3. Miotic Drug- Physostigmine (1% W/V), Pilocarpine (4% W/V)
• Apparatus: Rabbit holder, Droppers, Measuring scale, torch, cotton
wool, calculator (optional)
Dr. Sameer H. Sawant, Pharmacology, SIOP 3

4. Theory/ Principle:
• The eye is supplied both by sympathetic (radial fibres) and parasympathetic
nerves (circular fibers)
• Stimulation of sympathetic systems (radial fibers) produces mydriasis
• Stimulation of parasympathetic nerves (circular fibers) produces miosis
• Their paralysis produces opposite effects.
Dr. Sameer H. Sawant, Pharmacology, SIOP 4

5. Dr. Sameer H. Sawant, Pharmacology, SIOP 5

6. Dr. Sameer H. Sawant, Pharmacology, SIOP 6

7. Mydriatics
• Disrupting parasympathetic supply to the eye (atropine)
• Over- activating the sympathetic system (Phenylephrine)
• Use of Mydriatics:
1. They are used to reduce painful Ciliary spasm
2. for diagnosing Horners syndrome
3. examining the retina and deeper structures
4. for treating chronic simple glaucoma
5. corneal ulcers
6. used for retinoscopy particularly in children and very old patients.
Dr. Sameer H. Sawant, Pharmacology, SIOP 7

8. Miotics
• Miotics constrict the pupil by contracting iris sphincter
muscles (pilocarpine)
• or by inhibiting acetyl cholinesterase enzyme there by
facilitating actions of acetylcholine at transmitted sites
(Physostigmine).
• These mechanism increases outflow of aqueous humor and
decrease the intraocular pressure.
• These drugs are used during cataract and anterior chamber
surgeries, to treat wide angle glaucoma, xerostomia (dry
mouth)
Dr. Sameer H. Sawant, Pharmacology, SIOP 8

9. Light Reflex
• Light reflex is checked with a torch
• A pencil torch is best suited for this purpose
• Always Put the light from side (back) and bring it to the
front
• Do not put the light from the front side of the rabbit.
• Observe the changes in the diameter of pupil when light is
put into eye.
• Note any decrease or increase in pupillary diameter
• Take 3 readings.
Dr. Sameer H. Sawant, Pharmacology, SIOP 9

10. Corneal Reflex
• It is tested with a fine cotton wool wick.
• Wick is made in such a manner that there is no protruding
part of cotton.
• Touch peripheral part of cornea with tip of cotton wick.
• Always bring forward the cotton wool from the side (back).
• Rabbit should not be able to see cotton wool or your hand.
• Blinking represents presence of corneal reflex.
• Do not forget to note down the 3 readings.
Dr. Sameer H. Sawant, Pharmacology, SIOP 10

11. Procedure:
1.Carefully handle the rabbit and please it in rabbit holder box
keeping the head outside.
2.Note down the pupil size of both eyes.
3.Observe light reflex by putting the light from side and then
to front (to and fro) and corneal reflex by touching a side of
the cornea with a cotton swab of tip.
4.Use pouch method for instillating of drops into the eye.
Dr. Sameer H. Sawant, Pharmacology, SIOP 11

12. Cont.
5.Put one drop of saline to the Right eye and consider it as
control eye.
6.Instill (mydriatic/miotic) in the Left eye and consider it as
test.
7.After adding the drops, press the medial canthus for 10
seconds.
8.Record the following parameters at 1 minute, 5, 10 and 15
minutes after instilling the drug and saline.
Dr. Sameer H. Sawant, Pharmacology, SIOP 12

13. Parameters to be measured:
• Diameter of the pupil
A. Light reflex
B. Corneal reflex
• Take 3 readings for every parameter and record observations in a
tabular form. Repeat the same procedure for other drug on separate
rabbits.
Dr. Sameer H. Sawant, Pharmacology, SIOP 13

14. Precautions:
• Do not touch central part of cornea it can cause
corneal ulcers/opacities
• This can lead to blindness as central part of
cornea is the main part of cornea used for
visibility
Dr. Sameer H. Sawant, Pharmacology, SIOP 14

15. Dr. Sameer H. Sawant, Pharmacology, SIOP 15
L R

16. Dr. Sameer H. Sawant, Pharmacology, SIOP 16
L R

17. Dr. Sameer H. Sawant, Pharmacology, SIOP 17
L
L
R
R

18. Observation Table
Effect of drugs on rabbit eye
Dr. Sameer H. Sawant, Pharmacology, SIOP
Result
Mydriatics
Mydriatics
Miotics
Miotics
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18

19. Classification of miotics and mydriatics
Dr. Sameer H. Sawant, Pharmacology, SIOP 19