PURPOSE: Placement of a sterile single-use cover over the tonometer tip may be a convenient and safe alternative method to repeated chemical disinfection. This study was undertaken to evaluate the accuracy and performance of Goldmann applanation tonometry using a sterile disposable silicone tonometer shield over the biprism tip. METHODS: The same investigator measured intraocular pressure in 120 eyes with and without the shield. The eyes were tested randomly first with either the uncovered or the covered tonometer to control for the possible effects of repeated tonometry influencing measurement differences. Readings were recorded independently in a masked fashion. RESULTS: The intraocular pressure measurements evaluated with the silicone shield caused an average overestimation of the true intraocular pressure of 1.9 +/- 1.9 mmHg (P = 0.0001). Covered and uncovered readings correlated well (r = 0.91, P = 0.0001). The sensitivity and specificity of the covered tonometry in detection intraocular pressures of 21 mmHg or higher (as measured without the shield) were 96.3% and 68.8%, respectively. Minor distortions of the normal-appearing fluorescein bands were seen in 5% of the tonometries, and the shield had to be replaced because of bubbles or wrinkles on the applanating surface in 3.3% of the measurements, which means that care must be taken when fitting the shield. CONCLUSIONS: Although covered and uncovered tonometry readings correlated well, an overall trend for a slightly increased measured intraocular pressure as a result of using the silicone shield over the Goldmann tonometer tip was found. The outstanding sensitivity of this procedure in detecting increased intraocular pressure suggests that it can be useful in screening for ocular hypertension and glaucoma.
RCT Entities:
PURPOSE: Placement of a sterile single-use cover over the tonometer tip may be a convenient and safe alternative method to repeated chemical disinfection. This study was undertaken to evaluate the accuracy and performance of Goldmann applanation tonometry using a sterile disposable silicone tonometer shield over the biprism tip. METHODS: The same investigator measured intraocular pressure in 120 eyes with and without the shield. The eyes were tested randomly first with either the uncovered or the covered tonometer to control for the possible effects of repeated tonometry influencing measurement differences. Readings were recorded independently in a masked fashion. RESULTS: The intraocular pressure measurements evaluated with the silicone shield caused an average overestimation of the true intraocular pressure of 1.9 +/- 1.9 mmHg (P = 0.0001). Covered and uncovered readings correlated well (r = 0.91, P = 0.0001). The sensitivity and specificity of the covered tonometry in detection intraocular pressures of 21 mmHg or higher (as measured without the shield) were 96.3% and 68.8%, respectively. Minor distortions of the normal-appearing fluorescein bands were seen in 5% of the tonometries, and the shield had to be replaced because of bubbles or wrinkles on the applanating surface in 3.3% of the measurements, which means that care must be taken when fitting the shield. CONCLUSIONS: Although covered and uncovered tonometry readings correlated well, an overall trend for a slightly increased measured intraocular pressure as a result of using the silicone shield over the Goldmann tonometer tip was found. The outstanding sensitivity of this procedure in detecting increased intraocular pressure suggests that it can be useful in screening for ocular hypertension and glaucoma.