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Tonopen versus Goldmann applanation tonometry for detecting restrictive thyroid eye disease
Imran Rahman1, Paul S Cannon, S Ahmed Sadiq
1Royal Manchester Eye Hospital, Manchester, United Kingdom.
Ophthalmic Plastic and Reconstructive Surgery
|January 22, 2010
Summary
Intraocular pressure (IOP) measurements in thyroid eye disease (TED) using Goldmann applanation tonometer (GAT) and Tono-Pen XL are similar in upgaze. Both instruments effectively detect increased IOP in restrictive TED.
Area of Science:
- Ophthalmology
- Ocular Biomechanics
- Thyroid Eye Disease Research
Background:
- Thyroid eye disease (TED) diagnosis involves intraocular pressure (IOP) assessment in primary gaze and upgaze to identify restrictive myopathy.
- Goldmann applanation tonometer (GAT) is traditionally used, measuring IOP on the central cornea in primary gaze and inferior cornea in upgaze.
- Tono-Pen XL offers an alternative, measuring IOP on the central cornea in both gaze positions.
Purpose of the Study:
- To compare IOP measurements in upgaze between the Goldmann applanation tonometer (GAT) and the Tono-Pen XL in patients with restrictive thyroid eye disease (TED).
- To determine if the Tono-Pen XL, measuring central corneal IOP, yields similar results to the GAT, measuring peripheral corneal IOP in upgaze.
Main Methods:
- Intraocular pressure (IOP) was measured using both GAT (central cornea, primary gaze; inferior cornea, upgaze) and Tono-Pen XL (central cornea, primary and upgaze).
- The study included 31 patients with restrictive TED and 21 control subjects.
- The primary outcome was the difference in IOP readings between the two instruments in upgaze for patients with restrictive TED.
Main Results:
- In control subjects, no significant difference was found between Tono-Pen XL and GAT readings in either primary gaze or upgaze (p = 0.99).
- Both instruments indicated a significant increase in IOP with upgaze in patients with restrictive TED compared to controls (p = 0.0006).
- No significant difference in upgaze IOP readings was observed between the GAT and Tono-Pen XL in patients with restrictive TED (p = 0.39).
Conclusions:
- Both the Goldmann applanation tonometer (GAT) and the Tono-Pen XL are suitable for measuring intraocular pressure (IOP) in patients diagnosed with restrictive thyroid eye disease (TED).
- The findings support the use of either tonometer for IOP assessment in the upgaze position for diagnosing restrictive TED.
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