Overview

Tonometry is a diagnostic procedure used to measure intraocular pressure (IOP). This is a fundamental examination in ophthalmology, particularly important for glaucoma screening and monitoring.

Intraocular pressure measurement is crucial for diagnosing and monitoring glaucoma, one of the leading causes of blindness worldwide. Accurate IOP measurement is essential for treatment decisions and disease progression monitoring.

Learn more in our comprehensive RxDx Ophthalmology Course

Indications

✓
Glaucoma Screening

Routine screening for high-risk patients

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Glaucoma Monitoring

Regular IOP monitoring in glaucoma patients

✓
Pre-operative Assessment

IOP measurement before eye surgery

✓
Post-operative Monitoring

IOP monitoring after eye procedures

✓
Ocular Hypertension

Monitoring elevated IOP without optic nerve damage

Contraindications

Absolute Contraindications

✗ Corneal abrasion or ulcer
✗ Active corneal infection
✗ Patient refusal

Relative Contraindications

✗ Severe corneal edema
✗ Recent corneal surgery
✗ Uncooperative patient

📋 Equipment Checklist

Check off items as you gather them:

Pre-procedure Preparation

Preparation includes explaining the procedure to patient, selecting appropriate tonometry method, calibrating equipment, ensuring proper patient positioning, and preparing for potential complications. All team members should understand their roles.

Step-by-Step Procedure

Step 1: Patient Preparation

Explain procedure to patient. Position patient at slit lamp. Apply topical anesthetic. Ensure patient comfort and cooperation.

⚠️ Common Mistakes to Avoid:

  • Inadequate explanation
  • Poor positioning
  • Insufficient anesthesia

💡 Pro Tip:

Explain that the procedure is quick and painless to reduce patient anxiety.

Step 2: Equipment Calibration

Calibrate tonometer using calibration block. Clean tonometer tip. Check equipment function.

⚠️ Common Mistakes to Avoid:

  • Skipping calibration
  • Poor cleaning
  • Equipment malfunction

💡 Pro Tip:

Always calibrate the tonometer before use for accurate readings.

Step 3: Corneal Staining

Apply fluorescein to cornea. Ensure adequate staining for Goldmann applanation. Wait for proper staining.

⚠️ Common Mistakes to Avoid:

  • Insufficient staining
  • Excessive fluorescein
  • Poor staining technique

💡 Pro Tip:

Use minimal fluorescein to avoid excessive staining.

Step 4: Tonometer Positioning

Position tonometer tip at corneal center. Align with slit lamp beam. Ensure proper contact.

⚠️ Common Mistakes to Avoid:

  • Off-center positioning
  • Poor alignment
  • Inadequate contact

💡 Pro Tip:

Center the tonometer tip on the cornea for accurate measurement.

Step 5: Pressure Measurement

Gently touch cornea with tonometer. Read pressure from scale. Record measurement.

⚠️ Common Mistakes to Avoid:

  • Excessive pressure
  • Poor reading technique
  • Inaccurate recording

💡 Pro Tip:

Apply gentle, consistent pressure for accurate readings.

Step 6: Documentation

Record IOP values. Compare with previous readings. Document any abnormalities.

⚠️ Common Mistakes to Avoid:

  • Poor documentation
  • Missing comparison
  • Incomplete records

💡 Pro Tip:

Always compare current IOP with previous measurements.

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Post-procedure Care

Post-procedure care involves documenting IOP values, comparing with previous readings, monitoring for complications, and determining if additional testing is needed. Regular IOP monitoring is essential for glaucoma patients.

Complications & Management

Complication Incidence Signs Management Prevention
Corneal abrasion Rare Pain, foreign body sensation, photophobia Topical antibiotics, follow-up Gentle technique, proper calibration
Infection Very rare Redness, pain, discharge Culture, antibiotics Proper sterilization, single-use tips
Inaccurate readings 5-10% Unusual IOP values Repeat measurement Proper calibration, technique
Patient discomfort 10-20% Anxiety, poor cooperation Reassurance, gentle approach Good communication, proper anesthesia

Clinical Pearls

💡

Explain that the procedure is quick and painless to reduce patient anxiety.

🎯

Always calibrate the tonometer before use for accurate readings.

⚡

Use minimal fluorescein to avoid excessive staining.

🔍

Center the tonometer tip on the cornea for accurate measurement.

📊

Apply gentle, consistent pressure for accurate readings.

🎨

Always compare current IOP with previous measurements.

⚠️

Normal IOP range is 10-21 mmHg, but varies by individual.