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F. A. Killian, N. M. Radcliffe, C. E. Starr; The Effect of Scleral Indentation on Intraocular Pressure. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5757.
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To determine the effect of scleral depression on intraocular pressure (IOP) during routine peripheral fundus examination.
Institutional review board approval for this experimental design was obtained from the Lenox Hill Hospital IRB. Twenty volunteers with no known ocular disease were enrolled in this study at Manhattan Eye, Ear and Throat Hospital. Baseline IOP was measured after pupillary dilation with 1% tropicamide and 2.5% phenylephrine using a hand-held tonomoter (Medtronic Solan Tono-Pen® XL). Scleral indentation was then performed with a metal scleral depressor by an experienced ophthalmologist who routinely performs this technique. At minutes two and four during the scleral indentation exam, a second examiner measured the IOP. Finally, IOP was remeasured two minutes after cessation of scleral depression.
The mean baseline IOP before scleral depression was 13.7 mmHg. During scleral depression, the mean IOP was 37.9 mmHg at two minutes and 41.2 mmHg at four minutes. These elevations in IOP from baseline were highly statistically significant (student's t-test, 1 tail, paired, p < 0.001). This demonstrates a mean increase of 24.2 and 27.5 mmHg, at two and four minutes, respectively. The IOP experienced at least a 100% increase in 18 of the 20 patients after scleral depression with an IOP maximum of 69 mmHg. The mean final IOP measured two minutes after the conclusion of scleral depression was 13.2 mmHg. The change from baseline IOP to final IOP was not statistically significant (student's t-test, 1 tail, paired, p < 0.29).
Scleral depression causes a significant elevation in IOP. It is unclear whether such transient elevations in IOP have clinical relevance in healthy eyes. However, the data may be useful when considering the risks, benefits and alternatives of performing scleral depression on patients with ocular pathology, specifically advanced glaucoma. Further exploration of the long-term effects of dramatic, transient elevations in IOP may be warranted.
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