A brief Pathophysiology Presentation on the topic " MYDRIATIC AND MIOTIC AGENTS AND DRUGS USED IN GLAUCOMA " Includes Both Open Angle and Closed Angle Glaucoma , their Mechanism Of Onset , Pathophysiology and Treatment ( Drugs Used In Glaucoma )

1. MYDRIATIC AND MIOTIC
AGENTS AND DRUGS USED IN
GLAUCOMA :)

2. FIRSTLY , WHAT IS A MYDRIATIC AGENT ??? :)
Agents that dilate the pupil. They may be either sympathomimetics
or parasympatholytics.

3. MYDRIATIC AGENTS :-
A mydriatic is an agent that induces dilation of the pupil. Drugs such as
tropicamide are used in medicine to permit examination of the retina and
other deep structures of the eye, and also to reduce painful ciliary muscle
spasm.
Normally, as part of the pupillary light reflex, the pupil dilates in the dark and
constricts in the light to respectively improve vividity at night and to protect
the retina from sunlight damage during the day.
A mydriatic pupil will remain excessively large even in a bright environment.
The excitation of the radial fibres of the iris which increases the pupillary
aperture is referred to as a mydriasis.

4. USE OF MYDRIATICS :-
More generally, mydriasis also refers to the natural dilation of pupils,
for instance in low light conditions or under sympathetic stimulation.
One effect of administration of a mydriatic is intolerance to
bright light (photophobia).

6. CLASSIFICATION :-

7. ACTIONS OF AVAILABLE MYDRIATICS :-

10. DRUGS WHICH CAN CAUSE MYDRIASIS :-
Mydriasis can be induced via modulation of adrenergic or cholinergic signalling.
Drugs that can cause mydriasis include:
● Stimulants (typically monoaminergics) such as amphetamines, cocaine, MDMA, and
mephedrone.
● Anticholinergics such as diphenhydramine, atropine, hyoscyamine, and
scopolamine antagonize the muscarinic acetylcholine receptors in the eye.
Blocking acetylcholine receptors, reduces the pupilary muscles' ability to constrict
and causes dilation .The antimuscarinic, tropicamide, may be used as a mydriastic
agent during surgery.
● Serotonergics such as LSD, psilocybin mushrooms, mescaline and 2C-B. . Similarly,
selective serotonin reuptake inhibitors can cause mydriasis.
● Dissociatives such as dextromethorphan (an SSRI and sigma-1 agonist).
● Certain GABAergic drugs, such as phenibut and GHB.
● Adrenergic agonists, such as phenylephrine and cyclomydril.

11. WHAT ARE MIOTICS ??
Miotics (drugs that cause the pupil to contract) improve the outflow of
aqueous as part of the treatment of glaucoma and reduce the risk of
a posteriorly luxated lens entering the anterior chamber.

12. WHAT IS GLAUCOMA ??
Glaucoma is a disease that damages your eye’s optic nerve.
It usually happens when fluid builds up in the front part of
your eye. That extra fluid increases the pressure in your
eye, damaging the optic nerve.

13. GLAUCOMA :-
Glaucoma is a group of eye diseases which result in damage to the
optic nerve and cause vision loss.
The most common type is open-angle glaucoma, in which the drainage
angle for fluid within the eye remains open, with less common types
including closed-angle glaucoma and normal-tension glaucoma.
Open-angle glaucoma develops slowly over time and there is no pain.
Peripheral vision may begin to decrease, followed by central vision, resulting
in blindness if not treated
Closed-angle glaucoma can present gradually or suddenly.
The sudden presentation may involve severe eye pain, blurred vision, mid-
dilated pupil, redness of the eye, and nausea.

14. PATHOPHYSIOLOGY :OPEN-ANGLE GLAUCOMA

16. PATHOPHYSIOLOGY : CLOSED ANGLE GLAUCOMA

18. RISK FACTORS :-
Vision loss from glaucoma, once it has occurred, is permanent.
Risk factors for glaucoma include increased pressure in the eye, a family history
of the condition, and high blood pressure.
For eye pressures, a value of greater than 21 mmHg or 2.8 kPa is often used, with
higher pressures leading to a greater risk.
However, some may have high eye pressure for years and never develop
damage.
Conversely, optic nerve damage may occur with normal pressure, known
as normal-tension glaucoma.

19. MECHANISM OF ONSET :-
The mechanism of open-angle glaucoma is believed to be slow exit of
aqueous humor through the trabecular meshwork, while in closed-angle
glaucoma the iris blocks the trabecular meshwork.
Diagnosis is by a dilated eye examination.
Often, the optic nerve shows an abnormal amount of cupping.

26. MEDICATIONS /DRUGS USED IN TREATMENT OF
GLAUCOMA :-
Intraocular pressure can be lowered with medication, usually eye drops. Several classes of
medications are used to treat glaucoma, with several medications in each class.
The possible neuroprotective effects of various topical and systemic medications are
also being investigated.
● Prostaglandin analogs, such as latanoprost, bimatoprost and travoprost,
increase uveoscleral outflow of aqueous humor. Bimatoprost also increases
trabecular outflow.
● Topical beta-adrenergic receptor antagonists, such as timolol, levobunolol,
and betaxolol, decrease aqueous humor production by the epithelium of the
ciliary body.
● Alpha2-adrenergic agonists, such as brimonidine and apraclonidine, work by a
dual mechanism, decreasing aqueous humor production and increasing
uveoscleral outflow.

28. ● Less-selective alpha agonists, such as epinephrine, decrease aqueous humor
production through vasoconstriction of ciliary body blood vessels, useful only in
open-angle glaucoma.
● Epinephrine's mydriatic effect, however, renders it unsuitable for closed-angle
glaucoma due to further narrowing of the uveoscleral outflow (i.e. further closure
of trabecular meshwork, which is responsible for absorption of aqueous humor).
Miotic agents (parasympathomimetics), such as pilocarpine, work by contraction
of the ciliary muscle, opening the trabecular meshwork and allowing increased
outflow of the aqueous humour. Echothiophate, an acetylcholinesterase
inhibitor, is used in chronic glaucoma.
● Carbonic anhydrase inhibitors, such as dorzolamide, brinzolamide, and
acetazolamide, lower secretion of aqueous humor by inhibiting carbonic
anhydrase in the ciliary body.

36. SUBMITTED TO :- DR . SUNANDA DASTIDAR
MADE BY :- RISHABH SHARMA
B.Sc CLINICAL RESEARCH

37. REFERENCES :-
https://www.sciencedirect.com/topics/medicine-and-dentistry/mydriatic-agent
https://www.aao.org/eye-health/diseases/what-is-glaucoma
https://en.wikipedia.org/wiki/Glaucoma
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