Disinfection Procedures for Medical Equipment

Questions and Answers

What should be used to avoid disrupting the epithelium of the cornea during the procedure?

Excessive illumination

Cotton tip applicator against the globe

Ghost mires (correct)

Direct pressure with the probe

What is the ideal thickness of the mires during the procedure?

0.25-0.30 mm (correct)

0.10-0.15 mm

0.30-0.35 mm

0.20-0.25 mm

What should be done if the mires appear unequal during the procedure?

Change the light source

Proceed with the measurement regardless

Adjust the slit lamp until they are equal and centered (correct)

Stop and restart the entire procedure

According to Imbert-Fick Law, how is the pressure inside an ideal sphere expressed?

Force divided by area Signup and view all the answers

What position should the patient's head be in during the procedure?

Tightly against the forehead with chin on chinrest Signup and view all the answers

What is the primary disadvantage of using the Rebound Tonometer for IOP measurement?

The patient must be sitting straight. Signup and view all the answers

Which factor is not a limitation of the Transpalpebral Tonometer?

Patient's corneal curvature Signup and view all the answers

How does the Rebound Tonometer determine the IOP based on the probe's movement?

By analyzing the voltage produced during deceleration. Signup and view all the answers

Which of the following methods can record IOP?

Tonometry method (e.g., GAT, iCare, NCT) Signup and view all the answers

What is the role of the pneumatic system in NCT systems?

To produce an air puff directed against the cornea. Signup and view all the answers

What principle does the MacKay-Marg tonometer utilize?

Indentation and applanation Signup and view all the answers

Which device is particularly useful in non-cooperative patients or children?

Tonopen Signup and view all the answers

In which situation is the Transpalpebral Tonometer particularly useful?

For home-monitoring IOP in special needs patients. Signup and view all the answers

What advantage does the Pascal-Dynamic Tonometer (DCT) provide over traditional applanation methods?

Contour matching Signup and view all the answers

What is the primary use of disposable latex covers in the Tonopen?

To ensure patient hygiene Signup and view all the answers

How does the IOP estimation change after LASIK and PRK?

Underestimated due to tissue removal Signup and view all the answers

Which characteristic of the MacKay-Marg tonometer helps identify the force of application?

Notch in the electrical waveform Signup and view all the answers

What is the function of the piezoresistive pressure sensor in the Pascal tonometer?

To convert eye pressure to electrical signals Signup and view all the answers

How many readings does the Tonopen typically take to provide an average?

4-10 readings Signup and view all the answers

What should be done first for contact lens wearers before a procedure involving NaFl?

Flush all the NaFl out of the eye Signup and view all the answers

How is intraocular pressure (IOP) affected by WTR astigmatism?

Underestimated by 1 mmHg for every 4 DC Signup and view all the answers

What is the primary cause of inaccurate readings when using the probe to measure IOP?

Eyelashes between the cornea and the probe Signup and view all the answers

What is a recommended treatment for superficial punctate keratitis (SPK)?

Artificial Tears PF Signup and view all the answers

When is it preferable to use Non-Contact Tonometry (NCT) instead of Goldmann Applanation Tonometry (GAT)?

For patients with anterior segment conditions Signup and view all the answers

What time of day do IOP readings tend to be highest?

Early morning, between 6:00 am - 8:00 am Signup and view all the answers

How much can IOP fluctuate over 24 hours?

3-5 mmHg Signup and view all the answers

What does a diurnal curve measure in glaucoma patients?

The consistency of IOP readings throughout the day Signup and view all the answers

What IOP difference between eyes should raise concern?

More than 4 mmHg Signup and view all the answers

What can be a result of poorly rinsing the probe after measurement?

Corneal edema Signup and view all the answers

How can pressure (P) be determined in the context of the cornea?

By measuring force (F) and area (A) Signup and view all the answers

Which factor is NOT listed as a potential error in Goldmann tonometry?

Patient age Signup and view all the answers

What is the effect of thinner corneas on Goldmann Applanation Tonometry (GAT)?

They cause underestimation of IOP Signup and view all the answers

What is a characteristic of Goldmann tonometry concerning corneal thickness?

It is more precise on average thickness corneas (550 μm) Signup and view all the answers

Which of the following statements about Goldmann tonometry is true?

It is a standard care measure for glaucoma patients Signup and view all the answers

What influence does the Valsalva maneuver have on intraocular pressure?

It increases IOP due to breath-holding Signup and view all the answers

Which factor could contribute to a falsely high IOP during Goldmann tonometry?

Pressure on the patient’s globe by examiner Signup and view all the answers

How does the presence of fluorescein affect the measurement in Goldmann tonometry?

It can show a pulsating pattern due to venous pulsation Signup and view all the answers

In which situation is it advised to finalize a patient's refraction prior to GAT?

When anesthesia is expected to cause blurry vision Signup and view all the answers

Which condition is described as ocular hypertension?

IOP greater than 21 mmHg without optic nerve head damage Signup and view all the answers

Study Notes

Disinfecting Solutions

Opticide: Disinfectant that does not damage the probe; requires 3 minutes of immersion.
Isopropyl alcohol 70%: Potential to damage probes; not as effective against Hepatitis B and C; requires rinsing and tapping dry.

Tonometer Procedure

Patient positioning: Must keep head against forehead and chin on chinrest for accurate measurements.
Fixation targets: Different targets for each eye (OD and OS).
Slit lamp adjustment: Set measuring drum to 1, light source at 60-65° temporal to the probe.
Observe and position probe close to cornea without sudden movements.

Probe Alignment and Use

Before touching the cornea, ensure probe is centralized.
Use cotton tip applicator to hold eyelids if needed, avoiding pressure on the globe.
Look for ghost mires (pale blue/gray semicircles) to ensure alignment and avoid epithelial disruption.

Mires Measurement

Ideal mire measurements: 0.25-0.30 mm; thick mires lead to falsely high readings, thin mires yield falsely low readings.
Align mires, if misaligned, follow the larger one for adjustment.

Imbert-Fick Law

States pressure inside a fluid-filled sphere is determined by the force needed to flatten the sphere's surface divided by the area flattened.
Variables like irregularity of the cornea may affect results.

Goldmann Tonometry Errors

Various factors influence accuracy: fluorescein amount, eye movements, and corneal conditions.
Patient anxiety or specific eye conditions can lead to inaccurate IOP measurements.

Corneal Thickness Impact

GAT most accurate with average thickness (~550 μm).
Thinner corneas may underestimate IOP; thicker corneas may overestimate.
Conversion tables for corneal thickness not widely used due to lack of consensus.

GAT Application

Performed prior to dilation; critical for glaucoma management.
Recommended to finalize refraction before GAT due to anesthesia-induced blurry vision.

Measurement Considerations

IOP varies throughout the day, highest readings in the early morning.
Discrepancies larger than 4mmHg between eyes may indicate underlying conditions.

Perkins Tonometer

A handheld version of Goldmann tonometry.

Advanced Tonometer Systems

MacKay-Marg/Tonopen: Electronics convert transmitted pressure to mmHg; useful for non-cooperative patients.
Pascal Tonometer: Uses contour matching and piezoresistive sensors; accounts for pulsatile IOP variations.
NCT: Utilizes pneumatic air puff for measurements, includes optoelectronic mechanisms.
Diaton (Transpalpebral Tonometer): Measures IOP through eyelid pressure; useful for special needs populations.

Rebound Tonometer (iCare)

Utilizes a magnetized probe to measure deceleration speed on contact; least contact time required.
Probes are disposable, allowing easy hygiene without disinfection.

Flatness and Astigmatism Considerations

Astigmatism impacts IOP readings; adjustments based on K readings help minimize errors.
Post-procedure examination for keratitis or abrasions is important to prevent complications.

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Description

This quiz covers the essential steps and precautions for disinfecting medical probes and equipment. It focuses on the use of Opticide and isopropyl alcohol, along with their effectiveness and guidelines to prevent damage. Test your knowledge on proper disinfection methods and safety measures in a clinical setting.