Vision 3: Intra-Ocular Pressure

Question 1

normal Range of Intraocular pressure

Answer 1

12-20 mmHg
* Increases in the morning & decreases in the evening

Question 2

Describe regulation of Intraocular pressure

Answer 2

Resistance to Outflow:
1. If IOP increases, irido-scleral angle increases
2. Causing Distention of Meshwork of trabeculae
3. Causing increase in drainage
4. Causing decrease in IOP

Pupil constriction & Dilatation:
1. Constriction causes opening of angle, decreasing IOP
2. Dilatation causing closure of angle, inceasing IOP

Question 3

Functions of Intra-Ocular Pressure (IOP)

Answer 3

Normal Focusing mechanism:
1. Decrease in IOP causes Relaxation of Suspensory Ligaments, This Increases Lens power
2.Increasing IOP causes Stretching fo the suspensory ligament, therefore Decrease lens power

Maintainance of spheroid shape of eye

Question 4

Definiton of Glaucoma

Answer 4

Increase in Intraocular pressure more than 21mmHg, or Optic Nerve hypersensitivity to pressure change

Question 5

Causes/Types of Glaucoma

Answer 5

Open angle glaucoma:
* Angle is not affected
* Increase in resistance of Meshwork/Canal of Schlem, which decrease the drainage of Aqueous Humour, Increasing IOP

Closed Angle Glaucoma:
* Foreward movement of Iris causes closure of Angle (EMERGENCY)

Question 6

Manifestations of Glaucoma

Answer 6

1. Sever pain
2. Inabilitty to accomodate Near vision
3. Blindness

Question 7

Treatement of Open angle Glaucoma

Answer 7

1. CA inhibitors: Diamox, Acetazolamide, Dorozlamide
2. Parasympatomemetic: Esirine, pilocarpine (pupillary constriction)
3. Surgical opening of spaces
4. Laser opening of spaces
5. Prostaglandin Analog

Question 8

Treatement of close angle Glaucoma

Answer 8

Surgical treatment (emergency)