FACTORS INFLUENCING INTRAOCULAR PRESSURE

Meidina Rahmah

Consultant

Dr. dr. Hj. Fidalia, SpM(K)

dr. Prima Maya Sari, SpM

Literature review

OPHTHALMOLOGY DEPARTMENT OF SRIWIJAYA UNIVERSITY

MOH. HOESIN HOSPITAL PALEMBANG2015

Introduction

• Normally intraocular pressure is 15.5 mmHg with SD 2.6 mmHg

• Intraocular pressure are influenced by secretion and outflow of aqueous humor

• Aquos humor is a fluid which filled anterior and posterior chamber

….. Introduction

• Disturbance of aqueous humor flow can cause increasing of intraocular pressure which lead to optical nerve damage

• It’s important to know aqueous humor flow and factors that influenced the intraocular pressure

Objective

To explain about anatomy ciliary body and anterior chamber, physiology of aqueous humor

andfactors that influenced

intraocular pressure

Anatomy & Physiology

Anatomy of the Ciliary Body

• Site of aqueous humor production • Anterior portion of the uveal tract,

whichis located between the iris and the choroid

• Consist of 2 zone anterior (pars plikata) & posterior (pars plana)

….. Anatomy

oblique

circular

longitudinal

Ciliary Muscle

Ciliary Vessels

….. Anatomy

• The major arterial circle is the immediate vascular supply of the iris and ciliary processes

• Each ciliary process is supplied by two branches of the major arterial circle:the anterior and posterior ciliary process arterioles

Ciliary Epitel

– Outer part pigmented epithelium, consist of cuboid cell and facing the stroma of theciliary process

– Inner part non pigmented epithelium,consist of collumnar epithelial, facing and lining the posterior chamber

Innervation of the Ciliary Body

Simpatis Parasimpatis

• Synapse in the superior cervical Ganglion• Postsynaptic fibers are distributed to the ciliary body vessels

• Edinger-Westphal nucleus to innervate the ciliary muscles

Anatomy of Anterior Chamber

• The iris separates the aqueous humorcompartment into a posterior and an anterior chamber

• Angle formed by the iris and the cornea is called the anterior chamber angle

• The deep of anterior chamber is varyIn normal emetrop 3 mm

• Volume 200 µL

….. Anatomy

• Anterior chamber angle is formed by: –Schwalbe’s line–Schlemm’s canal and Trabecular

meshwork–Scleral spur–Collector channel –Anterior border of the cilliary body – Iris

Schwalbe’s line- Termination of Descemet’s membrane

Schlemm’s canal- A continuos monolayer of nonfenestrated

endothelium and thin connective tissue wall

Trabecular meshwork Consists of a connective tissue coresurrounded by endothelium and may be divided into three portions: (a) uveal meshwork, (b) corneoscleral meshwork,

(c) juxtacanalicular tissue

Physiology

• Aqueous humor is a clear fluid that fillsand helps form the anterior and posterior chambers of the eye

• Secreted by the nonpigmented ciliary epithelium (NPE) from a substrate ofblood plasma.

….. Physiology

Intraocular pressure is depend on:

1. Rate of aqueous secretion2. Resistance of the outflow

channel3. Episcleral venous pressure

Functions of aqueous humor

• Brings oxygen and nutrients to cells of lens, cornea, iris

• Removes products of metabolism and toxic substances from those structures

• Provides mechanism for maintaining intraocularpressure

• High ascorbate levels protect against ultraviolet-induced oxidative products, e.g., free radicals

• Facilitates cellular and humoral responses of eye to inflammation and infection

Aqueous Humor Formation

3 mechanisms

Aqueous Humor Composition

– Inorganic ion and organic anion

–Carbohydrate–Glutation and urea–Protein–Growth modulary factors–Oxygen and CO2

Components

(mmol/kg H20)Plasma Aquos Vitreus

Na+

Cl-

HCO3-

Ascorbate

Glucosa

146

109

28

0,04

6

163

134

20

1,06

3

144

114

20-30

2,21

3,4

Aqueous Humor Outflow

Aqueous humor posterior chamber pupil anterior chamber. Aqueous humor exits the eye by passingthrough the 2 route:1.The trabecular (conventional) route

(90%)2. The uveoscleral (unconventional)

route (10%)

Factors that influenced intraocular pressure

Increase intraocular pressure

• Gender• Diurnal variation• Cardiovascular• Position • External pressure of eyeball

Factors that may increase intraocular pressureIncreasing of episclera vein pressureManuver ValsavaHold to breathUsage of tight collar atau tight necktieIncrease central vein pressureObstruction outflow of orbital veinIntubationPressure on eyeballBlefarospasmeCrying HyperthermiaHormonalHipotiroidismeThyroid eye diseaseDrugs unrelated to glaucoma therapyLysergic acid diethylamide (LSD)TopiramateCorticosteroidsAnticholinergicsKetamine

Decrease intraocular pressure• Age• Exercise• Trauma and inflamation

Factors that may decrease intraocular pressureAerobic exerciseAnesthetic drugsDepolarizing muscle relaxants such as succinylcholineMetabolic or respiratory acidosisHormonal influencesPregnancyDrugs unrelated to glaucoma therapyAlcohol consumptionHeroinMarijuana (cannabis)

Conclusion

• Intraocular pressure are influenced by secretion rate of aqueous humor andrate of outflow

• This fluid flow from posterior chamber pupil anterior chamber trabecular patyhway and uveoscleral pathway

• Intraocular pressure depends on many factors that may increase dan decrease

Thank You