Eye drug

By
Pharmacist
Salwan Salem
Human Eye (physiology ,Pathology ,and treatments)

Human Eye

Is the organ which gives the sense of sight .
Eye allows us to see and interpret the shapes , colors, and dimensions of objects by processing the light they reflect or emit.
The eye able to detect bright light or dim light , but cannot sense objects when light is absent.

Anatomy and physiology

The eye consists of a retinal –lined fibrovascular sphere which contains the aqeous humor , the lens and viterous body .
Retina Serves the primary purpose of photoreception
-Role of other structures :
act on focus image on retina , to regulate amount of light entering the eye , or to provide nutrition ,protection ,or motion .

Eye

1-Sclera : is white and opaque material , for protection
2- Cornea: white and transparent , for protection
3- Retina :
The sensory retina covers the inner posterior two thirds of the wall of the globe .

It consists of several layers :

Retina composed of 10 layers , from outside (nearest the blood vessel enriched chharoid )
To the inside ( nearest the gelatinous viterous humor)
The rods and cones , the light receptive elements of the retina ,transform physical energy into nerve impulses.

4-Lens

Is a biconvex, transparent , and avascular structure . It is suspended behind the iris by the a suspensory ligament , which connects it with the ciliary body
5 -The aqeous humor :
is transparent ,gelatinous fluid secreted from the ciliary epithelium , it is located in the anterior and posterior chambers of eye .






Accommodation in near and far vision

Glaucoma

Is deisease of the eye in which fluid pressure withen the eye rises .
IOP is the pressure caused by the fluid inside the eye that help maintain the shape of eye.
Normal IOP 10-21 mmHg
May lead to lose vision
Affect both eyes
Aqous humor builds up ,and increase pressure withen the eye

Aqueous humor flow in Glaucoma

Types of Glaucoma

1- Open angle glaucoma:
The most common type of G ( 90% )
Caused by : slow clogging of drainage canals , increased IOP
Open angle means the angle where the iris meets the cornea is a wide and opened as it should be.


2-Closed angle glaucoma :
Caused by blocked drainage canals , sudden rise in IOP
Which has closed angle between iris and cornea
3- Normal tension G
4-conginetal G

Symptoms

Loss of periphral vision
Sensitivity to light and glare
Problems with night vision
Blurred vision

Risk factors

Increased IOP
Age >60 yr
Race : African-American
Family history
Medical conditions: DM (3 times risk) , HT
Eye injury
CTS chronic use may develop secondary G.


Complications
Blind spots in peripheral vision
Tunnel vision
Total blindness

Diagnosis

Tonometry : to measure eye ball pressure , High IOP suggest Glaucoma
Optic nerve examination : check damage
Visual field exam : pt visual field ( area in front) will be mapped to check for visual loss

Treatment

There is no cure of Glaucoma , and if the optic nerve damaged ,it cannot be fixed
The progression of G can be controlled by
1- lowering IOP ,
2-increase drainage of aqeous humor (out flow) by prostoglandins ,
3- decrease production of Aqeous humor by B-Blockers , Carbonic anhydrase inhibitors .

4-Surgery to improve outflow of Aq.Humor:

Laser Surgery by trabeculoplasty , Filtering surgery by trabeculectomy .
5-Drainage implants : by inserting tube in eye to facilitate draining of Aq.humor to reduce Pressure


1-Prostoglandins
Treat open angle G
By increasing outflow of Aq.Humor
Ex: Latanoprost ( Xalatan)
Travoprost (Travatan)
S/E: mild reddening of eye , eyelid pigmentation , blurred vision

2- Betablockers

Reduce the production of IOP , by block the action of Symp. N .S , which leads to decrease IOP , the presice mechanism is uknown
Beta blocker
Ex: Timolol ( Timoptic)
Betaxalol ( Betoptic)
s/E: difficulty breathing , Bradycardia , decrease B.P, impotence .

3-Alpha adrenergic agonists

Reduce production of Aq.Humor and increase out flow .
Alpha 2 receptor agonist :
Ex: Brimonidine ( Alphagan)
Apraclonidine ( Lopidine )
S/E : irrigular H.R ,
high blood pressure , fatigue ,
swollen eyes , dry mouth .

4-Carbonic anhydrase inhibitors

-Systemic adminstration (oral) Ex: Acetazolamide
-Carbonic anhydrase is enzyme present in biochemical of aqueous humor. So it decrease Aq.humor production.
Ex: Dorzolamide (Trusopt) eye drops
Brinzolamide ( Azopt) eye drop s
-S/E : frequent urination

5-Miotic and cholinergic agents

Which increase out flow of Aq.Humor withen eyes .
Muscarinic receptor agonist
Ex: Pilocarpine (Isopto carpine)
S/E: Smaller pupils , Blurred vision .

summary

Treatments for Glaucoma
• Agents enhancing aqueous humor outflow
• Muscarinic agonists (pilocarpine)
• Prostaglandins (Latanaprost)
• Agents suppressing aqueous humor production
• ß adrenergic antagonists (Timolol)
• 2 adrenergic agonists (Aproclonidine)
• Carbonic anhydrase inhibitors (Acetazolamide)