CPT® Code 92120

Deleted

1. Indications

Tonography is performed for several specific indications related to intraocular pressure and the assessment of glaucoma. The following conditions may warrant the use of this procedure:

• Glaucoma Screening - Tonography is utilized to detect glaucoma by measuring the intraocular pressure and evaluating the outflow of aqueous humor.
• Monitoring of Intraocular Pressure - The procedure is indicated for patients with known glaucoma or those at risk of developing the condition, allowing for ongoing assessment of IOP changes.
• Evaluation of Aqueous Outflow - Tonography helps in understanding the dynamics of aqueous humor flow, which is crucial for diagnosing and managing various ocular conditions.

2. Procedure

The tonography procedure involves several key steps to accurately measure intraocular pressure. The following outlines the procedural steps:

• Step 1: Patient Preparation - The patient is positioned supine to facilitate access to the eye. Local anesthetic drops are administered to the cornea to ensure comfort during the procedure.
• Step 2: Placement of the Tonometer - The footplate of the tonometer is carefully placed on the cornea. This footplate is designed to have a span greater than that of the cornea, allowing for accurate indentation measurements.
• Step 3: Application of Weights - A plunger, which protrudes through a central hole in the footplate, is used to apply varying known weights to the cornea. These weights are added to the plunger assembly to create different levels of pressure.
• Step 4: Measurement of Indentation - As the plunger is moved vertically, it indents the cornea using the standard weights. The force required to achieve this indentation is recorded by a mechanical pointer that moves over a scale at the top of the tonometer.
• Step 5: Conversion of Measurements - The readings obtained from the mechanical pointer are converted into millimeters of mercury (mm Hg) using a graph, normogram, or conversion chart, which helps in determining the presence of glaucoma.
• Step 6: Alternative Method - Perilimbal Suction - In addition to the indentation method, the perilimbal suction technique may be employed, which intentionally increases intraocular pressure by impeding the circulation and flow of aqueous humor from the eye, providing further insights into IOP dynamics.

3. Post-Procedure

After the tonography procedure, patients may experience temporary discomfort or blurred vision due to the application of anesthetic drops and the pressure applied during the test. It is generally recommended that patients rest for a short period before resuming normal activities. Follow-up appointments may be scheduled to discuss the results of the tonography and any necessary further evaluations or treatments based on the findings. Additionally, patients should be monitored for any adverse reactions to the procedure, although serious complications are rare.