ABSTRACT
Context: Precise intraocular pressure (IOP) measurement is important in glaucoma practise. Various instruments are available today to accurately measure IOP. Thus, the question arises about which instrument to use and whether all of them can be used interchangeably. Aims: To assess the agreement between noncontact tonometer (NCT), rebound tonometer (RBT), Goldmann applanation tonometer (GAT), and dynamic contour tonometer (DCT) in measuring IOP. Subjects and Methods: 499 eyes of 250 patients were evaluated during a period of 24 months from September 2010 to August 2012 and measurement of IOP by NCT, RBT, GAT, and DCT was done in the given sequence. The agreement was assessed by use of the Bland–Altman plot keeping GAT as a gold standard technique. Results: The mean IOP value of NCT, RBT, GAT, and DCT was 15.9 ± 5.5, 15.9 ± 5.8, 15.9 ± 4.9, and 16.0 ± 4.7 mm of Hg, respectively. The limits of agreement of GAT with DCT, NCT, and RBT were found to be +5.4 to −5.2, −4.7 to +4.6, and −5.2 to +5.1 mm of Hg, respectively. Conclusions: A positive and strong correlation was found between newer tonometers and GAT, but the limit of agreement was clinically unacceptable. The use of a single tonometer should be practised at a glaucoma clinic for a patient at each follow‑up.
ABSTRACT
PURPOSE: To investigate the accuracy of intraocular pressure (IOP) measurement through a plano soft contact lens (SCL) in situ by a noncontact tonometer (NCT) and a rebound tonometer (RBT). METHODS: The IOP of 66 eyes of 33 subjects with no ocular pathology was measured by NCT (tonometer CT-80, TOPCON, Japan) and RBT (iCare rebound tonometry(TM), Tiolat Oy, Finland). IOP measurement was repeated through plano SCL (ACUVUE OASYS(R), Johnson & Johnson Vision Care Inc., USA) in situ. Statistical analysis was performed using the paired t-test. RESULTS: Mean IOP measured by NCT was 13.10 +/- 2.52 mmHg without SCL and 12.95 +/- 2.56 mmHg with SCL. Mean IOP measured by RBT was 14.13 +/- 2.94 mmHg without SCL and 13.84 +/- 2.75 mmHg with SCL. No significant statistical differences were found between IOP measured with and without SCL (p=0.47, p=0.11 respectively). CONCLUSIONS: Reliable measurement of IOP by NCT and RBT can be achieved through plano SCL.
Subject(s)
Contact Lenses, Hydrophilic , Eye , Intraocular Pressure , Vision, OcularABSTRACT
The authors' clinical experience has suggested that the noncontact tonometer (NCT) has a tendency to record a lower intraocular pressure(IOP) than the Goldmann applanation tonometer(GAT) after excimer laser photo refractive keratectomy(PRK). This study was done to verify this tendency. We performed PRK on 177 eyes of 122 patients using a VISX 20/20 excimer laser, and topical fluorometholone was used after PRK. The eyes were divided into three groups according to their ablation depths, and the IOP was measured with the GAT and the Topcon NCT before surgery and 1, 3, 6, 9, and 12 months postoperatively. The mean postoperative IOP measured with the GAT or the NCT decreased as compared with the mean preoperative IOP(GAT: 1.67 ~ 2.90 mmHg, NCT:5.27 ~ 6.54 mmHg). The mean NCT reading was 1.12 mmHg higher than the mean GAT reading preoperatively, but was 2.48 ~ 2.88 mmHg lower than the mean GAT reading postoperatively. Difference between GAT and NCT measurements postoperatively was more prominent in the group of deeper ablation. These results suggest that we should be cautious of evaluating the IOP measured with the GAT or the NCT after PRK.