Exophthalmometer

Exophthalmometer

An exophthalmometer used in clinical practice

An exophthalmometer is a medical instrument used for measuring the degree of forward displacement of the eyes, a condition known as exophthalmos. This condition is often associated with thyroid eye disease, particularly Graves' disease, but can also occur in other conditions such as orbital tumors or inflammation.

Function

The primary function of an exophthalmometer is to measure the distance between the lateral orbital rim and the anterior surface of the cornea. This measurement helps in assessing the degree of proptosis, which is the forward protrusion of the eye. Accurate measurement is crucial for diagnosing and monitoring the progression of diseases that cause exophthalmos.

Types of Exophthalmometers

There are several types of exophthalmometers, each with its own method of measurement:

• Hertel Exophthalmometer: The most commonly used type, it consists of a ruler with two mirrors that are placed at the lateral orbital rims. The examiner reads the measurement from the scale on the device.

• Luedde Exophthalmometer: A simpler device that uses a transparent ruler placed directly on the lateral orbital rim to measure the protrusion of the eye.

• Maddox Rod Exophthalmometer: Utilizes a series of parallel red lines to measure the degree of exophthalmos by aligning the lines with the corneal apex.

Clinical Use

In clinical practice, the exophthalmometer is used by ophthalmologists and endocrinologists to:

• Diagnose thyroid eye disease
• Monitor changes in eye protrusion over time
• Evaluate the effectiveness of treatments for conditions causing exophthalmos

Procedure

The procedure for using an exophthalmometer involves the following steps:

1. The patient is seated comfortably with their head in a neutral position. 2. The examiner positions the exophthalmometer at the lateral orbital rims. 3. The examiner aligns the device to ensure accurate measurement. 4. The measurement is read from the scale, indicating the degree of eye protrusion.

Related Pages

• Exophthalmos
• Thyroid eye disease
• Graves' disease
• Ophthalmology