The effectiveness of a three-step sterilization method for Goldmann tonometer prism: A cross-sectional study.

PURPOSE: To propose a three-step sterilization method for Goldmann tonometer prism (GTP) and to analyze the sterilization effects of each step. METHODS: 120 patients (240 eyes) who underwent Goldmann applanation tonometer (GAT) IOP measurement were enrolled in this study. GTPs were used individually for each patient and wiped by swabs soaked with 75% ethyl alcohol, ofloxacin eye drops, and 75% ethyl alcohol for at least 5 s. GTPs were directly pressed onto the surface of agar plates before (W0) and after three-step sterilization (W1, W2, and W3). All the agars were sent to the laboratory in 2 h and incubated at 37°C for 48 h. Subsequently, the growth of microbial species was assessed through visual inspection of the colonies at the inoculation points on the agar surface. RESULTS: Staphylococcus. epidermidis was the most frequently isolated bacterium and was observed in 23.33% of all prisms. Most of the bacteria were eliminated at W3 except Staphylococcus. epidermidis and Kocuria roseus in one case. The isolation rates of Staphylococcus genus and Staphylococcus. epidermidis were significantly decreased (both with P < 0.001). The number of bacteria types isolated from prisms at time point W2 and W3 had a statistically significant difference compared with W1 and W (both with P < 0.05), while W2 and W3 exhibited no significant difference. CONCLUSION: This three-step sterilization method for GTP proved to be effective and safe for repeated use. We recommend using ofloxacin to prevent the transmission of pathogens based on ethyl alcohol, which could also bring some economic benefits.

Comparison of intraocular pressure measurements with different contact tonometers in young healthy persons.

AIM: To analyze the correlation of Goldmann applanation tonometer (GAT), I-Care tonometer and Tono-Pen tonometer results in young healthy persons, and to investigate the influence of central corneal thickness (CCT) on intraocular pressure (IOP) measurements recorded with these tonometers. METHODS: We conducted a pilot clinical study in 78 eyes of 78 subjects aged 22-28 years old (44 women and 34 men; mean age 23.8±1.19y). IOP was measured using GAT, I-Care and Tono-Pen tonometers, followed by measurements of CCT. Statistical analysis was performed using SPSS 20.0. RESULTS: The mean IOPs and standard deviation (±SD) for GAT, I-Care and Tono-Pen were 15.62±2.281 mm Hg, 16.29±2.726 mm Hg and 16.32±2.393 mm Hg, respectively. The mean CCT was 555.15±29.648 µm. Clear positive correlations between GAT and I-Care, GAT and Tono-Pen, and I-Care and Tono-Pen tonometers were found (r=0.867, P<0.001; r=0.861, P<0.001; r=0.915, P<0.001, respectively). In comparison between devices, Bland-Altman analysis showed a significant mean difference (MD) in the measurements by GAT and I-Care of -0.679 mm Hg and by GAT and Tono-Pen of -0.705 mm Hg ( P<0.001), but there was no significant difference between I-Care and Tono-Pen ( P>0.05). Both non-gold standard tonometers were affected by CCT; that is, both I-Care and Tono-Pen tonometer values were significantly higher with higher CCT means (>555 µm; MD=-1.282, P<0.001; MD=-0.949, P<0.001, respectively) compared with GAT. CONCLUSION: Both I-Care and Tono-Pen tonometers overestimated IOP compared with the GAT values. Either the I-Care or Tono-Pen tonometer could be used instead of GAT because there was no significant difference between their results. Higher CCT values (>555 µm) were associated with overestimated IOP values.

Corneal biomechanical properties: precision and influence on tonometry.

PURPOSE: To assess the precision and reproducibility of the corneal biomechanical parameters, and their relationships with the intraocular pressure (IOP) measured with the Goldmann tonometer and a noncontact tonometer. METHODS: Readings for biomechanical properties and for IOP measured with the Goldmann and noncontact tonometers, were taken on one randomly selected eye of 106 normal subjects, on each one of two measurement sessions. Measurements with the ocular response analyzer (ORA) and the noncontact tonometer were randomized, followed by the measurement of central corneal thickness and with the Goldmann tonometer. RESULTS: Repeatability coefficients for CCT, corneal hysteresis (CH) and corneal resistance factor (CRF) in Session 1 were ± 0.01 µm, ± 3.05 mmHg and ± 2.62 mmHg, respectively. The mean CCT, CH, CRF, Goldmann and noncontact tonometry did not vary significantly between sessions. Reproducibility coefficients for CCT, CH and CRF were ± 0.02 µm, ± 2.19 mmHg and ± 1.97 mmHg, respectively. Univariate regression analysis showed that CCT, CH and CRF significantly (P<0.0001) correlated with the IOP measured with the Goldmann and noncontact tonometers (and with the differences between tonometers) in Session 1. There were no significant correlations with the differences between tonometers in Session 2. Multivariate analysis revealed a minimal effect of CCT on Goldmann measurements but a significant effect on those of the noncontact tonometer. CONCLUSIONS: Measurement of the biomechanical properties of the cornea, using the ORA, are repeatable and reproducible, affect Goldmann tonometry less than noncontact tonometry, and have a minimal influence on the difference in measured intraocular pressure between tonometers.

Clinical Comparision of the ProTon and the Goldmann Applanation Tonometer

The recently developed ProTon tonometer is a small hand-held instrument which has less chances of infectious ocular diseases transmission and corneal abrasion than other types of tonometer. We compared the intraocular pressures taken by the ProTon tonometer with those by the Goldmann applanation tonometer in 290 eyes of 145 patients. The results were as follows: 1. The difference of the intraocular pressures between the ProTon tonometer and the Goldmann tonometer is less than 3mmHg in 91.03% of the estimation, and less than ImmHg in 64.83%. 2. The average intraocular pressure measured by the ProTon tonometer is lower than that by the Goldmann applanation tonometer. In the higher intraocular pressure zone, the difference of intraocular pressures between the two is more increased. 3. The correlation between the intraocular pressures measured by the ProTon tonometer and those by the Goldmann tonometer is very high(correlation coefficient 0.98). According to the above results, we conclude that the ProTon tonometer can be used more accurately and conveniently for both patient and examiner than other classic instruments.

Intraocular Pressure Assessment in Vitrectomized Gas-filled Eyes

We assessed the accuracy of Goldmann or Schi-(phi)tz tonometric readings in the gas filled vitrectomized eyes. We performed pars plana vitrectomy with or without lensectomy in 8 rabbit eyes, and in 6 enucleated porcine eyes. Fluid-air exchange was done at the end of the procedure. Intraocular pressure was measured using Goldmann tonometer and Schi-(phi)tz tonometer and was compared with true pressure which was monitored by manometer with indwelling catheter in the intravitreal cavity. Goldmann and Schi-(phi)tz tonometry always showed lower presure value than manometeric one(P0.05).

Comparison of the Noncontact Tonometer with Goldmann Tonometer

Several kinds of non-contact tonometers have been used since the first non-contact tonometer was introduced in the 1970's in order to measure intraocular pressure with easiness and accuracy. However several problems were still remained because of:he inaccuracy of the non-contact tonometer in high and low range of intraocular pressure. A new non-contact tonometer (Model CT-20, Japan) was recently introduced by Topcon Company to evaluate the clinical efficacy of the non-ccntact tonometers. The authors measured the intraocular pressure with Topcon tonometer, AO tonometer and Pulsair non-contat tonometer and compared the results with those measured with Goldmann tonometer. The results were as follows: 1) The correlation coefficient between Goldmann and Topcon tonometer was 0.8452 (p=0.001), Goldmann and Pulsair tonometer was 0.7084 (p=O.OOl) and Goldmann and AO tonometer was 0.6048 (p=O.OOl) in the normal eyes. 2) The correlation coefficient between Goldmann and Topcon tonometer was 0.8651 (p=0.0001) in the ocular hypertensive or open angle glaucoma eyes. 3) The correlation coefficient between Goldmann and Topcon tonometer was 0.6987 (p=0.000l) in the low lOP eyes. 4) The correlation coefficient between Goldmann and Topcon tonometer was 0.6829 (p=0.0001) in the high myopic eyes. As above, a new-contact tonometer (Model CT-20, Japan) made by Topcon Company was relatively accurate in measuring not only the intraocular pressure of normal eyes but that of ocular hypertensive, low IOP and high myopic eyes.