不同角膜厚度下非接触眼压计与Schiotz眼压计测量眼压的比较

目的：比较不同角膜厚度下非接触眼压计与Schiotz眼压计测量结果的差异。 方法：对314例627眼分别用角膜测厚仪测量角膜厚度,非接触眼压计与Schiotz眼压计测量眼压,根据角膜厚度分为：较薄组（角膜厚度≤530μm）、正常组（530μm＜角膜厚度≤570μm）、较厚组（角膜厚度＞570μm）。采用配对t检验比较不同角膜厚度下两种测量结果的差异,并通过Bland-Altman进行一致性评价。 结果：角膜厚度较薄组170眼,正常组301眼,较厚组156眼。两种方法在较薄组、正常组、较厚组三组中的眼压值分别为12.82±2.67,12.84±2.37mmHg;13.67±2.66,1358±2.41mmHg;15.45±2.91,14.76±2.39mmHg。两种方法测量结果在角膜厚度正常和偏薄组中差异无统计学意义,偏厚组中差异有统计学意义。 结论：在角膜厚度≤570μm的人群中,眼压的检查可在非接触眼压计和Schiotz眼压计间选择一种检查;对于角膜厚度＞570μm的人群,需参考两种方法检查结果,进一步检查排除青光眼。     

动态轮廓眼压计在正常人群中的应用及其影响因素分析

目的评价动态轮廓眼压计（DCT）与Goldmann压平眼压计（GAT）测量值之间的关系,寻找DCT眼压测量值的影响因素;分析DCT所测眼压脉动振幅（OPA）与DCT眼压值、中央角膜厚度（CCT）、角膜屈光力（CCV）、眼轴长度（AL）、前房深度（ACD）、收缩压（SBP）、舒张压（DBP）和心率（HR）的关系。方法分别测量正常人60例60眼的DCT眼压、GAT眼压、CCT、CCV、AL、ACD以及HR、SBP、DBP等指标,比较GAT、DCT2种眼压计测量的相关性及DCT测量值的影响因素。结果 DCT与GAT所测眼压平均值分别为（16.04±2.57）mmHg和（14.20±2.93）mmHg。DCT眼压值较GAT眼压值高,差异有统计学意义（t=6.454,P〈0.01）。DCT眼压值与GAT眼压值呈正相关（r=0.684,P〈0.01）。DCT眼压值与CCT不相关（r=0.212,P=0.105）,GAT眼压值与CCT呈正相关（r=0.291,P=0.024）。60例正常人的OPA均值为（2.50±0.89）mmHg,OPA与年龄、DCT眼压值、CCT、SBP、DBP、HR均不相关（P〉0.05）,与CCV呈正相关（r=0.343,P=0.007）。结论在正常人群中DCT眼压值与GAT眼压值有较好的相关性,DCT的眼压测量值不受CCT、CCV等因素的影响。DCT眼压值、CCT、SBP、DBP、HR等对OPA无明显影响。     

使用不同眼压计比较翼状胬肉术后绷带镜对眼压的影响

目的：利用回弹式眼压计(RT)及非接触式眼压计(NCT)测量并比较翼状胬肉术后配戴治疗用绷带镜时与裸眼眼压的差异。

方法：选取2019-04/06在开封市中心医院开封眼病医院手术治疗的翼状胬肉患者(鼻侧原发性翼状胬肉小于4mm且术后配戴治疗用绷带镜)50例50眼。于术后14d用RT及NCT分别在戴镜状态、裸眼状态测量患者眼压,比较并分析翼状胬肉术后治疗用绷带镜对眼压测量的影响。

结果：RT在戴镜状态、裸眼状态测得的眼压分别为18.20±3.19、15.17±3.80mmHg,相差3.04±1.79mmHg,且前后两次测量具有良好的相关性(r=0.884,P<0.001); NCT在戴镜状态、裸眼状态测得的眼压分别为15.74±3.23、13.19±3.89mmHg,相差2.55±1.88mmHg,且具有良好的相关性(r=0.876,P<0.001); 在戴镜状态及裸眼状态,两种设备测量所得眼压分别相差2.46±1.45、1.98±1.67mmHg,RT测量结果均显著高于NCT测量结果(P<0.001)。

结论：翼状胬肉术后应用RT、NCT测量配戴治疗用绷带镜状态与裸眼状态的眼压一致性均较好,但在配戴治疗用绷带镜时两种眼压计均有高估患者眼压风险,且应用RT在戴镜状态及裸眼状态眼压高估较NCT更明显。     

Effects of topical anaesthetics and repeated tonometry on intraocular pressure

Purpose: To investigate the effects of repeated measurements of intraocular pressure (IOP) using Goldmann applanation tonometry (GAT) and applanation resonance tonometry (ART) to identify mechanisms contributing to the expected IOP reduction. Methods: A prospective, single‐centre study with six healthy volunteers. Consecutive repeated series (six measurements/serie/method) were made alternately on both eyes for 1 hr with oxybuprocaine/fluorescein in the right eye and tetracaine in the left. The left eye was Pentacam^® photographed before and repeatedly for 20 min after the IOP measurements. On a separate occasion, the same volunteers received the same amount of anaesthetic drops for 1 hr but without repeated IOP measurements. Results: A significant IOP reduction occurred with both ART and GAT in the oxybuprocaine‐treated eye, ?4.4 mmHg and ?3.8 mmHg, respectively and with ART in the tetracaine eye, ?2.1 mmHg. There was a significant difference in IOP reduction between the oxybuprocaine and tetracaine eyes with ART. There was a significant drop in anterior chamber volume (ACV) immediately after the IOP measurements, ?12.6 μl that returned to pretrial level after 2 min. After 1 hr of receiving anaesthetic eye drops (without IOP measurements), the IOP decreased significantly in the oxybuprocaine eye for both ART and GAT, ?3.1 and ?1.7 mmHg, respectively, but not in the tetracaine eye (p = 0.72). Conclusion: The IOP reduction cannot be explained solely by aqueous humor being pressed out of the anterior chamber. While significant IOP reduction occurred with both tetracaine and oxybuprocaine after repeated mechanical applanation, the IOP reduction was significantly greater with oxybuprocaine.     

Precision and accuracy of the ICare tonometer – Peripheral and central IOP measurements by rebound tonometry

Purpose: The purpose of this study was to evaluate the ICare tonometers precision and accuracy and the extent to which intraocular pressure (IOP) measurements are influenced by measuring position. Methods: This was carried out by comparing the central and peripheral ICare‐IOP readings and comparing ICare‐ with the Goldmann applanation tonometer (GAT)‐IOP readings. IOP was measured using the ICare rebound tonometer on the right eye of 40 subjects, straight at the centre of the cornea (CS), straight 2 mm from the nasal and temporal limbus (NS and TS), and in 10 degrees nasally and temporally angled positions measured from the same location as CS (NA and TA). The IOP was also assessed with the GAT. Results: Central IOP (CS) was significantly (p < 0.001) greater than peripheral measurements (NS, TS, NA and TA) by approximately 3–4 mmHg. Centre IOP (CS) significantly overestimated by mean 2 mmHg and the peripheral measurements significantly underestimates approximately 1.4–2 mmHg compared with GAT readings. Conclusion: The ICare tonometer may be useful in a routine clinical setting for IOP screening, but the ICare measurement is not a substitute for the GAT measurement, when a precise and accurate IOP is desired.     

动态轮廓眼压计与Goldmann压平眼压计及非接触眼压计测量眼压的对比研究

目的探讨动态轮廓眼压计(DCT)与Goldmann压平眼压计(GAT)及非接触眼压计(NCT)测量眼压的准确性,并比较三种眼压计测量结果与中央角膜厚度(CCT)的相关性。设计前瞻性、比较性病例系列。研究对象连续选取90例(90眼)10~76岁正常人。方法采用KONAN非接触式角膜内皮镜测量CCT后,对所有入选者单眼以随机顺序采用Pascal型DCT、GAT及Topcon型NCT测量眼压。测量结果两两比较,并将眼压值与CCT进行直线回归分析。主要指标眼压值,Pearson相关系数。结果 90例正常人DCT眼压平均值(17.33±2.71 mm Hg)明显高于GAT(14.27±2.81 mm Hg)(P=0.000)及NCT(14.67±2.93 mm Hg)(P=0.000),平均差异分别为(3.06±2.01)mm Hg和(2.67±2.20)mm Hg;GAT与NCT之间平均差异为(-0.39±2.29)mm Hg(P=0.105)。DCT与GAT眼压值之间相关系数r=0.736(P=0.000);与NCT眼压值之间相关系数r=0.699(P=0.000)。GAT、NCT眼压值与CCT均明显相关(r=0.370,P=0.000;r=0.508,P=0.000);DCT眼压值与CCT无明显相关性(r=0.051,P=0.639)。DCT和GAT的差值与年龄无明显相关性(r=0.064,P=0.052)。结论 DCT测量的眼压值虽高于GAT及NCT,但不受CCT的影响,可能较GAT和NCT测量的眼压值更接近真实值。     

Comparison of the ICare® rebound tonometer with the Goldmann tonometer in a normal population

The aim of this study was to evaluate the accuracy of measurement of intraocular pressure (IOP) using a new induction/impact rebound tonometer (ICare) in comparison with the Goldmann applanation tonometer (AT). The left eyes of 46 university students were assessed with the two tonometers, with induction tonometry being performed first. The ICare was handled by an optometrist and the Goldmann tonometer by an ophthalmologist. In this study, statistically significant differences were found when comparing the ICare rebound tonometer with applanation tonometry (AT) (p < 0.05). The mean difference between the two tonometers was 1.34 +/- 2.03 mmHg (mean +/- S.D.) and the 95% limits of agreement were +/-3.98 mmHg. A frequency distribution of the differences demonstrated that in more than 80% of cases the IOP readings differed by <3 mmHg between the ICare and the AT. In the present population the ICare overestimates the IOP value by 1.34 mmHg on average when compared with Goldmann tonometer. Nevertheless, the ICare tonometer may be helpful as a screening tool when Goldmann applanation tonometry is not applicable or not recommended, as it is able to estimate IOP within a range of +/-3.00 mmHg in more than 80% of the population.     

Twenty-four hours intraocular pressure in keratoconic eyes assessed by applanation tonometry and Tono-Pen AVIA

AIM: To assess intraocular pressure (IOP) during the daily curve of intraocular pressure (DCPo) in keratoconic eyes and compare Goldmann applanation tonometer (GAT), without and with astigmatism correction (nGAT and cGAT) and Tono-Pen AVIA (TPA) assessment methods. METHODS: Thirty-nine keratoconic eyes of 24 patients were assessed. DCPo was evaluated with five IOP measurements; four were performed with a GAT (nGAT and cGAT), and a Tono-Pen AVIA (TPA) at various times throughout the day. RESULTS: Mean IOP DCPo values (mm Hg) were: nGAT, 9.9±2.6; cGAT, 11.3±2.6; TPA 12.3±3.1. Mean IOP DCPo differences (mm Hg) and Spearman’s correlation coefficients were as follows: cGATc-nGAT, 1.32±1.31, rs=0.879 (P<0.01); cGAT-TPA, -1.02±2.08, rs=0.723 (P<0.01); and nGAT-TPA, -2.35±2.23, rs=0.730 (P<0.01). Bland-Altman analysis for agreement between cGAT-TPA and nGAT-TPA mean IOP DCPo measurements revealed a mean difference of 1.02 (95%CI, 0.35-1.70) and 2.35 (95%CI, 1.62-3.07) mm Hg, respectively. Regression analysis yielded the following equation: TPA IOP=5.49+0.775×cGAT-0.015×ACD-0.299×corneal astig matism, which allowed us to infer TPA IOP values from other parameters. CONCLUSION: In keratoconic eyes, IOP peaks of DCPo measurements are identified at 6 a.m., independent of the tonometer. The mean DCPo values are: TPA>cGAT>nGAT. IOP TPA measures are predictive of cGAT values, adjusted according to anterior chamber depth and corneal astigmatism.     

Comparison of Proview phosphene tonometry with Goldmann applanation tonometry

BACKGROUND: To compare intraocular pressures obtained using a handheld pressure phosphene tonometer (PPT) (Proview, Bausch & Lomb Pharmaceuticals, Inc., Tampa, Fla.) with Goldmann applanation tonometry. METHODS: Comparative case series of 30 randomly selected patients. RESULTS: The readings obtained with the pressure phosphene tonometer display a higher mean and a larger standard deviation than those obtained with the Goldmann applanation tonometer (GAT). Differences between PPT and GAT readings tended to decrease as a function of increased Goldmann levels. The relation of Proview and Goldmann readings (r = 0.32) and the scatterplot were not consistent with the hypothesis that the 2 methods are equivalent. INTERPRETATION: Our results indicate that the pressure phosphene-type handheld tonometry method, which does not appear to provide an accurate and consistent measure of intraocular pressure, is substantially less reliable than the Goldmann method.     

Clinical performance of non-contact tonometry by Reichert AT550® in glaucomatous patients

Measuring intraocular pressure (IOP) by non-contact tonometry (NCT) has been demonstrated to be a valid and reliable technique to be used in primary eye care; it is easier to use, it does not transmit infectious diseases, and it is not necessary to use anaesthetic or staining eye drops. Recently, a new NCT device has showed an excellent level of agreement with Goldmann tonometry, but there are no records of its performance in glaucomatous eyes. To rectify this, IOP was measured in twenty-two patients (44 eyes) receiving medical treatment to control elevated IOP, with AT550 and Goldmann tonometry. Mean values of IOP were 18.98 +/- 2.77 and 19.08 +/- 3.02 mmHg using Goldmann and AT550, respectively. Plots of differences against means displayed good agreement (mean difference +/- limits of agreement, -0.09 +/- 3.30); this value was not significantly different from zero (t-test for dependent samples, p = 0.709). In conclusion, IOP values as measured with the AT550 NCT are clinically comparable with those obtained with Goldmann tonometry in glaucomatous patients. This validates this NCT not only for screening of IOP but to follow-up glaucomatous patients with a rapid, non-invasive method.     

Comparison of dynamic contour tonometry and Goldmann applanation tonometry following penetrating keratoplasty

Objective: To evaluate dynamic contour tonometry (DCT) versus Goldmann applanation tonometry (GAT) intraocular pressure (IOP) measurements in eyes that underwent penetrating keratoplasty (PKP).Design: Prospective, cross-sectional, observational study.Participants: Thirty-one eyes of 28 patients were examined after PKP.Methods: All eyes had undergone PKP with interrupted sutures. The postoperative period was more than 1 year for 25 eyes and less than 1 year for 6. Sutures were removed based on corneal topography and refraction. IOP was measured by both DCT and GAT methods and was correlated to the number of remaining sutures.Results: IOP readings were successfully obtained in 25/31 (80.6%) with DTC and in 21/31 (67.7%) with GAT (p = 0.25). In eyes with fewer than 4 remaining sutures, both methods were successful. In eyes with more than 4 sutures, the success rates of DCT and GAT were 66.7% and 44.4%, respectively (p = 0.18). In PKPs with a postoperative period of more than 1 year, the success rates of DCT and GAT were 96% and 84%, respectively (p = 0.16). In 20 eyes, both methods measured the IOP. The mean IOP obtained by DCT (16.6 [SD 2.8] mm Hg) was higher than the mean IOP obtained from GAT (15.1 [SD 3.6] mm Hg). The IOPs from the 2 instruments correlated significantly (p < 0.05) and the mean difference was 1.5 mm Hg.Conclusions: The success rate in measuring IOP with DCT and GAT did not show any statistically significant difference. Both methods were less effective measuring the IOP after recent PKPs and regrafts. However, DCT seemed to be superior to GAT in corneas with more than 4 remaining sutures and in PKPs performed more than 1 year earlier. The absolute values of IOP were higher with DCT than with GAT.     

Technical Note: A comparison of central and peripheral intraocular pressure using rebound tonometry

PURPOSE: To compare central and peripheral intraocular pressure (IOP) readings obtained with rebound tonometry. METHODS: Intraocular pressure was measured on the right eye of 153 patients (65 males, 88 females), aged from 21 to 85 years (mean +/- S.D., 55.5 +/- 15.2 years) with the ICare rebound tonometer at centre, and 2 mm from the limbus (in the nasal and temporal regions along the 0-180 degrees corneal meridian). RESULTS: Intraocular pressure values obtained with the ICare were 14.9 +/- 2.8; 14.1 +/- 2.5 and 14.5 +/- 2.7 mmHg at centre, nasal and temporal corneal locations, respectively. On average, nasal and temporal IOP readings were 0.75 and 0.37 mmHg lower than the central reading (p < 0.05 and p > 0.05, respectively). A highly significant correlation was found between central and peripheral measurements in nasal (r(2) = 0.905; p < 0.001) and temporal (r(2) = 0.879; p < 0.001) regions along the horizontal meridian. Almost 80% of patients presented nasal IOP values within +/-1 mmHg of the central value. CONCLUSIONS: Intraocular pressure values measured with the ICare rebound tonometer on the nasal corneal region is slightly lower on average and highly correlated with IOP values recorded at corneal centre. Both nasal and temporal readings are in good agreement with central IOP, and could be used to obtain a reliable estimate of rebound IOP in corneas where central readings cannot be taken.     

The relationship between central corneal thickness and Goldmann applanation tonometry

Background: The aim of this study was to investigate the relationship between Goldmann applanation tonometry and central corneal thickness in a large sample of healthy eyes. Method: Five hundred eyes of 500 subjects (253 women, 50.6 per cent and 247 men, 49.4 per cent) were analysed in a prospective healthy population study. Mean age of the sample was 31 ± 8 years. Goldmann applanation tonometry was carried out by one physician. Tonometric values were the mean of three consecutive readings. Subsequently, another physician carried out ultrasonic pachymetry with the DGH 2000 AP ultrasonic pachymeter (DGH Technology Inc, San Diego, USA). Ten measurements were made at the centre of the cornea of each eye. The lowest value was used for analysis. Results: Applanation tonometry and central corneal thickness were correlated (r = 0.184, p < 0.001). There was no significam correlation between corneal thickness and age (r = 0.083, p = 0.065), mean spherical equivalem refraction (r = 0.083, p = 0.065) or visual acuity (r = 0.036, p = 0.187). Conclusion: In normal eyes, there is no statistically significant correlation between changes of intraocular pressure and changes of central corneal thickness but they suggest a relationship between intraocular pressure and central corneal thickness. Goldmann applanation tonometry has a systematic error in accuracy of intraocular pressure readings of healthy eyes caused by its dependence on central corneal thickness. Measurement of corneal thickness by optometrists should be the first step in diagnosing intraocular pressure pathologies.     

Relationship between ocular pulse amplitude and systemic blood pressure measurements

Purpose: This study aimed to determine whether ocular pulse amplitude (OPA) measured with dynamic contour tonometry (DCT) is related to systemic blood pressure (BP) parameters. Methods: Blood pressure was measured continuously and simultaneously with OPA in one randomly selected eye in 29 healthy subjects. Systemic parameters of interest were: systolic and diastolic BPs and their difference (BP amplitude), and left ventricle ejection time (LVET; defined as the time between the diastolic trough and the incisural notch in the BP curve). In addition, the axial length (AL) of the eye was measured. Associations between OPA, AL and systemic cardiovascular parameters were analysed in a multivariate regression model. Results: Measurements of OPA ranged from 1.0 mmHg to 4.9 mmHg (mean 2.3 ± 0.9 mmHg, median 1.9 mmHg). In a univariate analysis with one predictor at a time, means of intraocular pressure (IOP) (p = 0.008), AL (p = 0.046) and LVET (p = 0.037) were significantly correlated with OPA, whereas systolic and diastolic BPs and their amplitude were not. A multiple linear regression analysis showed that mean IOP (p < 0.005), AL (p = 0.01) and LVET (p = 0.002) all independently contributed to OPA. Conclusions: The OPA readings measured with DCT in healthy subjects were not related to BP levels and amplitude. It seems that the OPA strongly depends on the time?course of the cardiac contraction. Regulating mechanisms in the carotid system as well as scleral rigidity may be responsible for dampening the direct effect of BP variations.     

The effect of contact lens-induced corneal edema on Goldmann applanation tonometry and dynamic contour tonometry

Purpose  To evaluate the effect of contact lens-induced corneal edema on intraocular pressure (IOP) measurements using Goldmann applanation tonometry (GAT) and dynamic contour tonometry (DCT) in Asian subjects. Participants  The study included 40 eyes of 20 normal volunteers with no evidence of ocular disease. Methods  Forty eyes of 20 healthy volunteers were required to wear soft contact lenses for 2 hours to induce corneal swelling. Central corneal thickness (CCT) and IOP were measured before and immediately after contact lens wear using specular microscope, GAT, and DCT. The IOP measurements by GAT and DCT were compared. The changes in the CCT and the IOP measurements after wearing contact lenses were assessed. Results  The mean CCT of the 40 eyes evaluated was 532.6 ± 31.6 μm. The mean IOP was 11.78 ± 2.04 mmHg for the GAT and 14.46 ± 1.89 mmHg for the DCT, and the difference was statistically significant (P < 0.001). After wearing contact lenses, the mean CCT was 553.2 ± 34.3 μm, which was 20.6 ± 12.9 μm greater than before wearing them (P < 0.001). The mean IOP measurements of the GAT and DCT were decreased after wearing the contact lenses. The mean decrease of the GAT values was 0.43 ± 1.95 mmHg, which was not statistically significant (P = 0.175). However, the mean decrease of the DCT readings, which was 0.75 ± 1.74 mm Hg, was statistically significant (P = 0.010). Conclusion  The IOP measurements with DCT were significantly higher than those with GAT in healthy Asian eyes. Although the mean IOP measurements of both the GAT and the DCT were decreased in the edematous cornea, IOP measurements of the DCT were more affected by corneal edema than were the GAT. The authors have no proprietary, commercial, or financial interests in any of the products described in this study.     

Diaton tonometry: an assessment of validity and preference against Goldmann tonometry

Background: To assess agreement between the Diaton, a new transpalpebral tonometer, and Goldmann applanation tonometry, the accepted gold standard. Design: Comparative study of two devices in a hospital setting. Participants: Two hundred and fifty‐one patients attending the eye casualty and general ophthalmology clinics at St James' University Hospital, Leeds between February and December 2009. Methods: Intraocular pressure was measured using Goldmann applanation tonometry and Diaton tonometry by one examining ophthalmologist. Patient preference for either technique was also recorded. Main Outcome Measures: Intraocular pressure measured by Diaton was compared with intraocular pressure measured by Goldmann applanation tonometry. Limits of agreement were determined using the Bland‐Altman method. Results: Two hundred and fifty right eyes underwent both Goldmann applanation tonometry and Diaton tonometry. Mean intraocular pressure was 13.8 ± 3.6 mmHg using Goldmann applanation tonometry and 13.2 ± 4.3 mmHg using Diaton tonometry. Upper and lower limits of agreement were +8.4 mmHg and ?9.6 mmHg, respectively. Order of intraocular pressure measurement and positioning did not influence limits of agreement in a clinically significant manner. Overall, more patients expressed preference for Diaton tonometry (40.2%) than Goldmann applanation tonometry (30.3%). Those aged 50 or less were more likely to prefer Diaton tonometry. Conclusions: The Diaton tonometer is portable, lightweight, user‐friendly and well tolerated by patients. However, it shows poor agreement with Goldmann applanation tonometry, thereby precluding it from being regarded as a substitute in routine clinical practice.     

轮廓动态眼压计测量准分子激光原位角膜磨镶术后眼压

目的通过与Goldmann眼压计(goldmann appla-nation tonometer,GAT)的比较,评价轮廓动态眼压计(dynamiccontour tonometer,DCT)在准分子激光原位角膜磨镶术(laser insitu keratomileusis,LASIK)前和术后眼压测量中的应用价值。方法在术前以及术后第1周和第4周,分别用GAT和DCT测量30例60眼的眼压,对所得结果采用SPSS 11.5统计分析软件进行统计学处理。结果中央角膜厚度(centralcorneal thickness,CCT)和GAT读数相关,而与DCT读数无关。术前眼压和术后第1周、第4周的眼压比较,GAT读数分别下降(5.00±1.12)mmHg和(5.45±1.13)mmHg,DCT则无显著性差异。结论LASIK导致的CCT变化可影响GAT测量结果的准确性,但对DCT无影响,因此,DCT更适用于正常眼以及曾接受LASIK手术眼的眼压测量。     

Predictability and limitations of non-invasive murine tonometry: comparison of two devices

Our purpose was to evaluate the accuracy, reproducibility and predictive ability of two non-invasive tonometers developed for intraocular pressure (IOP) measurements in the mouse. The prototype impact-rebound tonometer (I-R) and a prototype optical interferometry tonometer (OIT) utilizing a fiberoptic pressure sensor, were compared. Enucleated eyes from C57/BL6 mice were used for the calibration. The anterior chamber was cannulated and the IOP was adjusted in increments of 5 cm of H2O (open stopcock method). A calibration curve was generated for each individual eye along with a master calibration curve for all eyes. Two operators measured the IOP. The instruments were then used in alternating order to measure the IOP in C57/BL6 and in DBA2/J animals. The same eyes were subsequently cannulated and the error of the non-invasive tonometers was determined. Both tonometers yielded almost equivalent ex vivo calibration curves with individual R2 of 0.9878 and 0.9902 respectively. Both instruments were highly reproducible. In vivo the I-R tonometer underestimated while the OIT overestimated the IOP. This error was systematic and therefore predictable. The confidence intervals of this error were determined by comparing the IOP estimates provided by each tonometer with the measurements obtained invasively by cannulation in vivo. The 95% CI of the error were 2.36 mmHg for the I-R and 2.62 mmHg for the OIT respectively. Non-invasive tonometry in the mouse is feasible. Both non-invasive instruments provide accurate and reproducible measurements with the OIT requiring calibration curves for each individual investigator.