Tonometer

Tonometer

1. TONOMETERY Presented by : B.OPTOM

2. Contents : Introduction to Tonometery What is IOP ? Measurement of IOP Classification of Tonometery Clinical uses

3. INTRODUCTION : TONOMETER – It is a device that measures the Intraocular pressure. Most tonometers are calibrated to measure pressure in millimeters of Mercury ( mmHg ). NORMAL IOP -: 10-20 mmHg

4. CLINICAL USES -: Diagnosis and management Abnormally high IOP. Suggest the presence of Glaucoma.

5. MANOMETERY – measured by inserting a cannula directly into the anterior chamber which is connected with manometer. Disadvantage – Needs general anesthesia. Not practical method for human beings. Use – For experiment, research work on ANIMAL eye.

6. INDENTATION TONOMETER : SCHIOTZ TONOMETER – PRINCIPAL – Based on principal that a plunger will indent a soft eye more than a hard eye.

7. PROCEDURE- Sterilization. Paitent counseling Supine position. Topical anesthetic. Fixation target(Thumb). Place tonometer directly onto the cornea vertically. Note scale reading. Antibiotic. ADVANTAGE – Cheap , Portable ,Very good for camp screening. DISADVANTAGE - False reading , corneal abrassion.

8. GOLDMAN TONOMETER : Concept was introduced by Goldman in 1954. Consists of double prism mounted on a standard slit lamp. BASED ON – Imbert- Fick Law. P=W/A

9. PROCEDURE -: Paitent counselling . Pt comfortably positioned. Topical anesthesia. Place fluorescin strip in the lower fornix. Room light should be dimmed. Chin rest. Cornea and biprism is illuminated by cobalt blue filter light . These prisms are then advanced untill it just touches the apex of cornea. At this point 2 semi circles are viwed.

10. Advantages Accurate reading No indentation Disadvantages Need slit lamp Dark room procedure Staining light necessary

11. PERKIN’S HAND HELD: Same type of Goldman applanation tonometer. Used with pt in any position. The light source is powered by battery. ADVANTAGE – Portable, usally used infants and in children.

12. TONOPEN -:(Mackay-Marg) Including its power source Wt only 60g. 185 mm long. 25 mm wide. 2. Fully portable 3. Pocket tonopen. 4. Held in any position 5. It converts IOP into electric wave. Advantage – Portable, useful in pts with nystagmus, useful in scarage cornea Disadvangte- Costly ,Required in supine position.

13. NON CONTACT TONOMETER: A]AIR PUFF - Applanates the cornea by means of jet of air. IOP readings compare favourably with goldman tonometery. ADVANTAGE – Instrument is beneficial in mass Glaucoma screenings . Requires no anesthetics with proper use. No risk of injuring the cornea. B]PULSE AIR – Non contact tonometer that can be used in any position.

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