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Marco Cuadros, Jose A Paczka, Yesenia Yolanda Dorantes Diez, Montserrat Romo Sainz; Scleral Indentation Measurement of IOP with Schiötz Tonometry. Comparison with Rebound and Goldmann Tonometries.. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2693. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
In cases with disorders affecting central corneal integrity almost any type of tonometry may be precluded. The purpose of this study is to compare alternative options to determine IOP when central cornea could be impaired. Schiötz tonometry (ST) measured in the superior temporal sclera and rebound tonometry (RT) applied in the peripheral cornea are compared with central Goldmann applanation tonometry (GAT).
Non-consecutive patients visiting a specialized glaucoma center were invited to participate in the study. Informed consent was obtained from all selected participants. Methods of tonometry were used in random order. Under topical anesthesia (tetracaine ophthalmic drops), ST was performed with a 5.5 g weight or 7.5 g weight (if results were less than 4 in the scale reading) at 3 mm to the superior temporal corneo-scleral limbus, then IOP was calculated using the conversion tables; RT was done with an Icare ic-100 device applied to the most peripheral temporal cornea; and GAT was done in a masked fashion during two times if a difference between measurements was less than 3 mmHg, or three times if the difference was greater than 3 mmHg. Ultrasound pachimetry was also performed to obtain the central corneal thickness (CCT).
Forty two eyes from 21 glaucoma patients with healthy corneas were included in the study. Participants had a mean age of 57.6 ± 9.8 years old, a mean CCT of 551.5 ± 35.4 microns. Mean IOP values with ST, RT and GAT were 17.1 ± 5.3, 16.0 ± 4.8, 16.5 ± 4.6 mmHg, respectively showed no statistical difference among groups. Largest variations were found within ST measurements (≥ 7 mm Hg in three cases). Coefficients of variation were not different (0.3, 0.3, and 0.28). IOP values of ST vs. GAT and ST vs. RT were moderately correlated (R = 0.65 and 0.67, respectively; P = 0.0001 for both correlations). A strong correlation was observed between RT and GAT (R = 0.79, P = 0.001). A slight non-significantly negatively correlation (R ≤ 0.22) was observed among methods of tonometry and mean CCT values.
Scleral Schiötz tonometry and peripheral cornea rebound tonometry are comparable to Goldmann applanation tonometry and may be used as an alternative method in clinical practice to determine IOP when conventional devices and techniques might be inadequate or unreliable due to central corneal abnormalities
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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