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Change in intraocular pressure during point-of-care ultrasound.

Berg C, Doniger SJ, Zaia B, Williams SR - West J Emerg Med (2015)

Bottom Line: Post-US examination IOP values were not significantly different than baseline (average -0.15mmHg, p=0.42).Overall, the resulting change in IOP with US transducer placement is considerably less than the mean diurnal variation in healthy subjects, or pressure generated by physical examination, and is therefore unlikely to be clinically significant.However, it is important to take caution when performing ocular ultrasound, since it is unclear what the change in IOP would be in patients with ocular trauma.

View Article: PubMed Central - PubMed

Affiliation: North Memorial Health Care, Department of Emergency Medicine, Robbinsdale, Minnesota.

ABSTRACT

Introduction: Point-of-care ocular ultrasound (US) is a valuable tool for the evaluation of traumatic ocular injuries. Conventionally, any maneuver that may increase intraocular pressure (IOP) is relatively contraindicated in the setting of globe rupture. Some authors have cautioned against the use of US in these scenarios because of a theoretical concern that an US examination may cause or exacerbate the extrusion of intraocular contents. This study set out to investigate whether ocular US affects IOP. The secondary objective was to validate the intraocular pressure measurements obtained with the Diaton® as compared with standard applanation techniques (the Tono-Pen®).

Methods: We enrolled a convenience sample of healthy adult volunteers. We obtained the baseline IOP for each patient by using a transpalpebral tonometer. Ocular US was then performed on each subject using a high-frequency linear array transducer, and a second IOP was obtained during the US examination. A third IOP measurement was obtained following the completion of the US examination. To validate transpalpebral measurement, a subset of subjects also underwent traditional transcorneal applanation tonometry prior to the US examination as a baseline measurement. In a subset of 10 patients, we obtained baseline pre-ultrasound IOP measurements with the Diaton® and Tono-Pen®, and then compared them.

Results: The study included 40 subjects. IOP values during ocular US examination were slightly greater than baseline (average +1.8mmHg, p=0.01). Post-US examination IOP values were not significantly different than baseline (average -0.15mmHg, p=0.42). In a subset of 10 subjects, IOP values were not significantly different between transpalpebral and transcorneal tonometry (average +0.03mmHg, p=0.07).

Conclusion: In healthy volunteer subjects, point-of-care ocular US causes a small and transient increase in IOP. We also showed no difference between the Diaton® and Tono-Pen® methods of IOP measurement. Overall, the resulting change in IOP with US transducer placement is considerably less than the mean diurnal variation in healthy subjects, or pressure generated by physical examination, and is therefore unlikely to be clinically significant. However, it is important to take caution when performing ocular ultrasound, since it is unclear what the change in IOP would be in patients with ocular trauma.

No MeSH data available.


Related in: MedlinePlus

Graphic representation of the modified apparatus setup. The study subject is in a seated upright position, with a closed eyelid. The ultrasound transducer (US) is placed over the eyelid and the Diaton® transpalpebral tonometer (D) placed superior to the transducer.
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f2-wjem-16-263: Graphic representation of the modified apparatus setup. The study subject is in a seated upright position, with a closed eyelid. The ultrasound transducer (US) is placed over the eyelid and the Diaton® transpalpebral tonometer (D) placed superior to the transducer.

Mentions: This was a pilot study using a convenience sample. Once identified and consented for enrollment, each subject was assigned a study identification number and the researchers recorded data as it was collected. Each subject underwent three intraocular pressure measurements: prior to ultrasound, during ultrasound, and following ultrasound. All IOP measurements were performed in triplicate, and the mean values were recorded. A baseline IOP measurement first was obtained and recorded for either the right or left eye of each subject. This was recorded as the “pre-US” IOP. We used the Diaton® transpalpebral tonometer (BiCom Inc. Long Beach, NY). The manufacturer’s instructions recommend performing measurement on a person in the seated upright position, with a partially open eye by placing the device along the tarsal plate of the superior eyelid. We amended the technique, performing the measurement on a closed eyelid. The subject was placed in a seated position with eyes closed; the tonometer was centered on the eyelid at the superior aspect of the globe and angled perpendicular to ground level (Figure 1). After obtaining the baseline IOP measurements, ocular US was performed on the same eye. A 10-5MHz linear transducer (M-Turbo, Sonosite Inc.) was used and US gel was liberally applied to the transducer surface. The examiner’s hand was braced against the subject’s maxilla to minimize transmitted force. The transducer was placed directly on the closed eyelid, and the optimal transverse US image was obtained. While maintaining this image, a second researcher simultaneously performed transpalpebral tonometry by placing the Diaton® superior to the US transducer (Figure 2). This second IOP measurement was recorded as the “intra-US” IOP. Lastly, the US transducer was removed from the subject’s eyelid and the final transpalpebral IOP was measured and recorded as the “post-US” IOP.


Change in intraocular pressure during point-of-care ultrasound.

Berg C, Doniger SJ, Zaia B, Williams SR - West J Emerg Med (2015)

Graphic representation of the modified apparatus setup. The study subject is in a seated upright position, with a closed eyelid. The ultrasound transducer (US) is placed over the eyelid and the Diaton® transpalpebral tonometer (D) placed superior to the transducer.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4380377&req=5

f2-wjem-16-263: Graphic representation of the modified apparatus setup. The study subject is in a seated upright position, with a closed eyelid. The ultrasound transducer (US) is placed over the eyelid and the Diaton® transpalpebral tonometer (D) placed superior to the transducer.
Mentions: This was a pilot study using a convenience sample. Once identified and consented for enrollment, each subject was assigned a study identification number and the researchers recorded data as it was collected. Each subject underwent three intraocular pressure measurements: prior to ultrasound, during ultrasound, and following ultrasound. All IOP measurements were performed in triplicate, and the mean values were recorded. A baseline IOP measurement first was obtained and recorded for either the right or left eye of each subject. This was recorded as the “pre-US” IOP. We used the Diaton® transpalpebral tonometer (BiCom Inc. Long Beach, NY). The manufacturer’s instructions recommend performing measurement on a person in the seated upright position, with a partially open eye by placing the device along the tarsal plate of the superior eyelid. We amended the technique, performing the measurement on a closed eyelid. The subject was placed in a seated position with eyes closed; the tonometer was centered on the eyelid at the superior aspect of the globe and angled perpendicular to ground level (Figure 1). After obtaining the baseline IOP measurements, ocular US was performed on the same eye. A 10-5MHz linear transducer (M-Turbo, Sonosite Inc.) was used and US gel was liberally applied to the transducer surface. The examiner’s hand was braced against the subject’s maxilla to minimize transmitted force. The transducer was placed directly on the closed eyelid, and the optimal transverse US image was obtained. While maintaining this image, a second researcher simultaneously performed transpalpebral tonometry by placing the Diaton® superior to the US transducer (Figure 2). This second IOP measurement was recorded as the “intra-US” IOP. Lastly, the US transducer was removed from the subject’s eyelid and the final transpalpebral IOP was measured and recorded as the “post-US” IOP.

Bottom Line: Post-US examination IOP values were not significantly different than baseline (average -0.15mmHg, p=0.42).Overall, the resulting change in IOP with US transducer placement is considerably less than the mean diurnal variation in healthy subjects, or pressure generated by physical examination, and is therefore unlikely to be clinically significant.However, it is important to take caution when performing ocular ultrasound, since it is unclear what the change in IOP would be in patients with ocular trauma.

View Article: PubMed Central - PubMed

Affiliation: North Memorial Health Care, Department of Emergency Medicine, Robbinsdale, Minnesota.

ABSTRACT

Introduction: Point-of-care ocular ultrasound (US) is a valuable tool for the evaluation of traumatic ocular injuries. Conventionally, any maneuver that may increase intraocular pressure (IOP) is relatively contraindicated in the setting of globe rupture. Some authors have cautioned against the use of US in these scenarios because of a theoretical concern that an US examination may cause or exacerbate the extrusion of intraocular contents. This study set out to investigate whether ocular US affects IOP. The secondary objective was to validate the intraocular pressure measurements obtained with the Diaton® as compared with standard applanation techniques (the Tono-Pen®).

Methods: We enrolled a convenience sample of healthy adult volunteers. We obtained the baseline IOP for each patient by using a transpalpebral tonometer. Ocular US was then performed on each subject using a high-frequency linear array transducer, and a second IOP was obtained during the US examination. A third IOP measurement was obtained following the completion of the US examination. To validate transpalpebral measurement, a subset of subjects also underwent traditional transcorneal applanation tonometry prior to the US examination as a baseline measurement. In a subset of 10 patients, we obtained baseline pre-ultrasound IOP measurements with the Diaton® and Tono-Pen®, and then compared them.

Results: The study included 40 subjects. IOP values during ocular US examination were slightly greater than baseline (average +1.8mmHg, p=0.01). Post-US examination IOP values were not significantly different than baseline (average -0.15mmHg, p=0.42). In a subset of 10 subjects, IOP values were not significantly different between transpalpebral and transcorneal tonometry (average +0.03mmHg, p=0.07).

Conclusion: In healthy volunteer subjects, point-of-care ocular US causes a small and transient increase in IOP. We also showed no difference between the Diaton® and Tono-Pen® methods of IOP measurement. Overall, the resulting change in IOP with US transducer placement is considerably less than the mean diurnal variation in healthy subjects, or pressure generated by physical examination, and is therefore unlikely to be clinically significant. However, it is important to take caution when performing ocular ultrasound, since it is unclear what the change in IOP would be in patients with ocular trauma.

No MeSH data available.


Related in: MedlinePlus