Comparison of Goldmann applanation and dynamic contour tonometry before and after cataract surgery

[Intraocular pressure elevation after vitrectomy-Goldmann applanation tonometry measures lower intraocular pressure than dynamic contour tonometry]

Hintergrund

Das dynamische Konturtonometer PASCAL (DCT) ist ein digitales, der natürlichen Hornhautgeometrie angepasstes Kontakttonometer. Verglichen wurde das DCT mit dem Goldmann-Applanationstonometer (GAT).

Methodik

In einer prospektiven Querschnittstudie wurden 100 Augen vor und nach Pars-plana-Vitrektomie (ppV) vergleichend mit dem GAT und DCT gemessen. Verwendete Endotamponaden waren verschiedene Gase und Silikonöle. Erfasst wurden der präoperative intraokulare Druck (IOD), postoperative Druckveränderungen und die Intertonometerdifferenz.

Ergebnisse

Präoperativ lag der mittlere IOD mit dem GAT gemessen bei 15,8 ± 5,2 mm Hg und dem DCT bei 17,5 ± 5,9 mm Hg. Am ersten postoperativen Tag stieg bei Augen, die mit Gas versorgt wurden, der Druck im Mittel um 2,5 mm Hg (p = 0,035) an. Das DCT erfasste 18 Augen (19,1 %) mit einem postoperativen IOD von ≥ 25 mm Hg. Postoperativ maß das GAT den IOD im Schnitt 2,5 mm Hg niedriger und bei expansiver Gasendotamponade im Mittel um 3,0 mm Hg niedriger als das DCT. Bei IOD-Werten von postoperativ über 20 mm Hg lag das GAT im Mittel 4,7 mm Hg unter dem DCT. Zehn von 18 Augen mit IOD ≥ 25 mm Hg wurden mit dem GAT nicht als hypertensiv (≥ 25 mm Hg) erkannt. Bei 13 % maß das DCT am 1. postoperativen Tag einen um mindestens 6 mm Hg höheren IOD als das GAT. In einem Extremfall wurde der IOD mit dem GAT bei Gasendotamponade um 12 mm Hg unterschätzt.

Schlussfolgerung

Postoperative Druckanstiege nach ppV sind gefürchtete Komplikationen und können zu irreversiblem Visusverlust führen. Abhängig von der verwendeten Endotamponade misst das GAT den IOD niedriger als das DCT – besonders bei Druckspitzen durch expansive Gase. Die postoperative IOD-Messung nach ppV ist bedeutend und die Messwerte von GAT und DCT können abweichen.

[Management of posttraumatic ocular hypotony]

The posttraumatic ocular hypotony (3% after ocular contusion, 50-74% after open globe injury) can lead to severe secondary damage of the eyeball. In addition to corneal folds, ciliary body and choroidal detachment, papilledema e vacuo and macular folds, the shrinking of the eye can lead to substantial visual impairment. Subsequently, the contralateral eye may react with ocular hypertension. The cause of the hypotony must be identified and causally treated. A preservation of the globe is possible if more than 210 ° of the ciliary body are intact. One of the major causes of posttraumatic hypotony is cyclodialysis. Smaller cyclodialysis clefts respond to a cycloplegic treatment, larger clefts require a surgical approach. The direct cyclopexy can be combined with primary wound repair or pole to pole surgery. An alternative consists of silicone oil endotamponade or occlusion of Schlemm's canal. The posttraumatic ocular hypotony is complex and requires exact diagnostics to be able to differentially and specifically treat the causes of hypotony.

Changes in intraocular pressure after intraocular eye surgery-the influence of measuring technique

AIM

To investigate the changes in intraocular pressure (IOP) before and after intraocular surgery measured with Goldmann applanation tonometry (GAT) and pascal dynamic contour tonometry (PDCT), and assessed their agreement.

METHODS

Patients who underwent trans pars plana vitrectomy (TPPV) with or without cataract extraction (CE) were included. The IOP was measured in both eyes with GAT and PDCT pre- and postoperatively, where the non-operated eyes functioned as control.

RESULTS

Preoperatively, mean IOP measurements were 16.3±6.0 mm Hg for GAT and 12.0±2.8 mm Hg for PDCT for the operated eyes. Postoperatively, the mean IOP dropped to 14.3±5.6 mm Hg for GAT (P=0.011) and rose up to 12.7±2.6 mm Hg for PDCT (P=0.257). Bland-Altman analysis showed a poor agreement between GAT and PDCT with a mean difference of 2.9 mm Hg preoperatively and 95% limits of agreement ranging from -3.2 to 9.0 mm Hg. Postoperatively, the mean difference was 1.2 mm Hg with 95% limits of agreement ranging from -8.3 to 10.7 mm Hg. There were no significant differences between the TPPV and TPPV+CE group, except when measured with PDCT postoperatively (P=0.012).

CONCLUSION

The IOP is reduced after surgery when measured with GAT and remained stable when measured with PDCT. However, the agreement between GAT and PDCT is poor. Although PDCT may be a more accurate predictor of the true IOP, it seems less suitable for daily use in the clinical practice.

Influence of preoperative astigmatism on corneal biomechanics and accurate intraocular pressure measurement after micro-incision phacoemulsification

AIM

To define the corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg) and corneal compensated intraocular pressure (IOPcc) prior to and following coaxial micro-incision phacoemulsification in patients with corneal astigmatism.

METHODS

Of 97 patients with cataracts were enrolled in the study. Group 1 included patients with corneal astigmatism (K1-K2) values of K1-K2<+1.0 D, and group 2 with values of K1-K2 ≥+1.0 D and ≤+2.25 D. Coaxial micro-incision phacoemulsification of a corneal incision of 2.0 mm with intraocular lens (IOL) implantation was performed. CH, CRF, IOPg, IOPcc, waveform score (WS) were measured preoperatively and one week, one month postoperatively using an Ocular Response Analyzer. Axial length (AXL) was calculated by Tomey Optical Biometer OA 2000.

RESULTS

Group 1 consisted of 51 patients with mean corneal astigmatism value of +0.49±0.25 D. Group 2 included 46 patients with astigmatism of +1.43±0.43 D. In group 1, CRF (t=2.68, P<0.05), CH (t=2.64, P<0.05) and WS (t=3.51, P<0.05) were significantly lower one week postoperatively, when compared to the preoperative values. CRF significantly decreased (t=3.61, P<0.05) when measured one month following the surgery. In group 2 CH (t=5.92, P<0.05), and WS (t=3.96, P<0.05) were significantly lowered one week after cataract surgery. Moreover, we observed a significant decrease in IOPg (t=2.24, P<0.05), CRF (t=5.05, P<0.05) and CH (t=2.31, P<0.05) one month after phacoemulsification. There was no statistically significant (t=-0.83, P=0.41) difference in AXL between study groups.

CONCLUSION

CRF, CH and IOPg are reduced in patients with preoperative corneal astigmatism equal or higher than +1.0 D and lower than +2.25 D. Hence, bias of IOPg measurement in these patients may cause underestimation of the real IOP both before and after cataract surgery. The measurement of IOPcc allows the precise assessment of IOP pre- and postoperatively, independently on corneal astigmatism, CH and CRF values.

Comparison of intraocular pressure fluctuation before and after cataract surgeries in normal-tension glaucoma patients

Purpose:

Cataract surgeries have been shown to reduce intraocular pressure. We used a Sensimed Triggerfish® contact lens sensor to compare intraocular pressure levels and their fluctuation between before and after cataract surgeries in patients with normal-tension glaucoma.

Methods:

This was a prospective open-label study. Thirteen patients with normal-tension glaucoma were included. All patients underwent a 1-month washout and discontinued glaucoma medications during this study. In each eye, intraocular pressure fluctuations over 24 h were measured with the contact lens sensor before and at 3 months after the cataract surgery. We compared intraocular pressure levels and their fluctuation between before and after cataract surgeries. We used two approaches to evaluate the amplitude of intraocular pressure fluctuations: dual-harmonic regression analysis, and measurement of the difference between the maximum and the minimum value.

Results:

The mean pre-operative intraocular pressure was 14.7 ± 2.2 mm Hg and mean post-operative intraocular pressure was 11.4 ± 2.2 mm Hg. Cataract surgery significantly decreased intraocular pressure (p = 0.0005). In both methods, the post-operative fluctuations in intraocular pressure over 24 h were significantly smaller than their pre-operative counterparts (dual-harmonic regression analysis: p = 0.0171; difference between the maximum and the minimum: p = 0.0398).

Conclusion:

Cataract surgery decreased both intraocular pressure values and intraocular pressure fluctuations in normal-tension glaucoma patients.

Analysis of differences in intraocular pressure evaluation performed with contact and non-contact devices

Background

To evaluate differences of intraocular pressure (IOP) measurements performed with Goldmann applanation tonometer (GAT), dynamic contour tonometer (DCT), rebound tonometry (RT), Ocular Response Analyzer (ORA) and Corvis ST (CST) in eyes screened for refractive surgery.

Methods

One eye, only the right one, of 146 patients was included in this study. Each participant was submitted to a corneal analysis with Scheimpflug camera and IOP evaluation with GAT, DCT, RT, ORA and CST. Differences in IOP values obtained thanks to each instruments were compared and then correlations between these discrepancies and morphological features such as mean keratometry (MK) and central corneal thickness (CCT) provided by Pentacam were studied. Software used to run statistical evaluations was SPSS, version 18.0.

Results

Study participants had a mean age of 33.1 ± 9.2 years old. IOP values observed in this study were 15.97 ± 2.47 mmHg (GAT), 17.55 ± 2.42 mmHg (DCT), 17.49 ± 2.08 mmHg (RT), 18.51 ± 2.59 mmHg (ORA) and 18.33 ± 2.31 mmHg (CST). The mean CCT was 560.23 ± 31.00 μm, and the mean MK was 43.33 ± 1.35 D. GAT provided significant lower values in comparison to all other devices. DCT and RT gave significantly lower intermediate IOP values than those measured with ORA and CST. All the IOP measures and the differences between devices were significantly correlated with CCT.

Conclusions

According to our data, although our findings should be confirmed in further studies, GAT tonometer cannot be used interchangeably with DCT, RT, ORA and CST.

Goldmann Applanation Tonometry versus Dynamic Contour Tonometry after Vitrectomy with Silicone Oil Endotamponade

PURPOSE

To evaluate the agreement of intraocular pressure (IOP) measurements using dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) in eyes after vitrectomy with silicone oil endotamponade and controls.

METHODS

In this prospective comparative study, IOP was measured with GAT and DCT in 30 eyes with oil endotamponade 1-3 days after vitrectomy and 40 untreated controls. In addition, ocular pulse amplitude (OPA), corneal pachymetry (CCT), and axial length (AL) were measured.

RESULTS

GAT values in the oil group were significantly higher compared to control eyes (mean GAT oil 13.6 ± 5.1 mmHg; mean GAT control 10.8 ± 2.1 mmHg; p = 0.003). There was no significant difference in DCT measurements (mean DCT oil 12.0 ± 4.1 mmHg; mean DCT control 11.9 ± 2.9 mmHg; p = 0.9). This led to a significant difference of GAT-DCT between the oil and control group (mean difference of GAT-DCT oil 1.6 ± 4.7 mmHg; mean difference of GAT-DCT control -1.1 ± 2.6 mmHg; p = 0.004). The difference between GAT and DCT was negatively correlated with the mean IOP measured by both methods (r = -0.36, p = 0.02) and positively correlated with CCT only in the control group (r = 0.36, p = 0.02), as well as to AL only in the oil group (r = 0.46, p = 0.01). The OPA did not differ significantly between groups.

CONCLUSION

GAT and DCT showed a good agreement in control eyes. The difference of GAT and DCT is significantly changed in eyes after vitrectomy with silicone oil endotamponade. Our findings suggest that GAT overestimates IOP in this situation.

[Reduction of intraocular pressure and ocular pulse amplitude during general anesthesia]

AIM

Measurement of the intraocular pressure (IOP) is an important tool for glaucoma diagnostics in children or patients with impaired cooperation. General anesthesia (GA) may significantly influence the IOP. This study aimed to evaluate the reduction of IOP during GA.

PATIENTS AND METHODS

The IOP was measured in 229 patients in a recumbent position in the non-operated eye prior to and 5 min after the beginning of GA with a dynamic contour tonometer (DCT).

RESULTS

The average IOP decreased from 19.9 ± 3.7 mmHg prior to GA to 14.1 ± 3.5 mmHg 5 min after beginning GA (p < 0.0001, IOP decrease 30 %). The GA caused a decrease of up to 2 mmHg in 6.1 %, 2-4 mmHg in 18.8 %, 4-6 mmHg in 21.0 %, 6-8 mmHg in 36.6 %, 8-10 mmHg in 13.6 %, 10-12 mmHg in 2.2 % and more than 12 mmHg in 1.7 % of the eyes. The ocular pulse amplitude (OPA) decreased from a mean of 3.4 ± 1.5 mmHg to 1.9 ± 1.0 mmHg (p < 0.0001, OPA decrease 41 %) under GA.

CONCLUSION

A significant decrease of IOP (mean 6 mmHg) occurs during GA and under extreme conditions up to 13.8 mmHg. A decrease of OPA of 1.5 mmHg should be taken into consideration for patients under general anesthesia and under extreme conditions up to 7 mmHg.

Goldmann Applanation Tonometry Versus Dynamic Contour Tonometry After Vitrectomy

PURPOSE

The aim of the study was to investigate the agreement of intraocular pressure (IOP) measurement using dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) in eyes after vitrectomy with intraocular gas endotamponade, in eyes after vitrectomy with no tamponade, and in controls.

METHODS

In this prospective comparative study IOP was measured with GAT and DCT in 41 eyes with gas endotamponade (sulfur hexafluoride 20%) 1 to 3 days after vitrectomy, in 32 postvitrectomy eyes with intraocular water, and in 46 control eyes with no history of glaucoma or intraocular surgery. Corneal pachymetry and axial length measurements were additionally performed.

RESULTS

The mean difference between GAT and DCT (GAT-DCT) in gas-filled eyes was 3.1 mm Hg [SD=6.2 mm Hg], that in eyes after vitrectomy with no tamponade was 0.4 mm Hg (SD=4.8 mm Hg), and in control eyes was 0.4 mm Hg (SD=3.8 mm Hg). No significant correlation was found between the differences of GAT and DCT (GAT-DCT) and the mean IOP of GAT and DCT in water-filled eyes (r=-0.25, P=0.18) and control eyes (r=0.23, P=0.13), but a significant correlation was found in the gas-filled eyes (r=0.71, P<0.0001). A significant correlation between central corneal thickness and the mean difference of both methods was seen only in the control group (r=0.36, P=0.03).

CONCLUSIONS

IOP as determined by DCT underestimates IOP in gas-filled eyes compared with GAT, as GAT values were on average 3.1 mm Hg higher compared with those of DCT. The extent of IOP underestimation using DCT increases with higher IOP values. In the group of eyes after vitrectomy and in normal eyes we found a generally good agreement between the 2 methods, although high interindividual discrepancies were present. Our findings suggest that the 2 devices should not be used interchangeably in IOP evaluation after vitrectomy with gas endotamponade, which remains a difficult challenge.

Intraocular pressure evaluation in healthy eyes and diseased ones using contact and non contact devices

PURPOSE

To analyze and compare intraocular pressure (IOP) values measured in healthy subjects (HS), keratoconus (KC) patients and patients that underwent myopic photorefractive keratectomy (REF), using Goldmann applanation tonometry (GAT), dynamic contour tonometry (DCT), ocular response analyzer (ORA) and Corvis ST (CST).

METHODS

The study included 76 eyes of 76HS, 15 eyes of 15 KC patients and 18 eyes of 18 subjects that underwent REF. Each participant underwent a complete ophthalmic evaluation, IOP measurement with GAT, DCT, ORA and CST.

RESULTS

HS showed a mean GAT value of 15.62±2.33 mm Hg, a mean DCT value of 17.44±2.51 mm Hg, a mean ORA value of 15.99±3.58 mm Hg and a mean CST value of 17.24±3.44 mm Hg. KC showed a mean GAT value of 15.07±1.83 mm Hg, a mean DCT value of 17.01±1.96 mm Hg, a mean ORA value of 13.58±2.99 mm Hg and a mean CST value of 14.37±1.89 mm Hg. REF showed a mean GAT value of 14.06±1.51 mm Hg, a mean DCT value of 15.12±2.34 mm Hg, a mean ORA value of 16.85±2.4 mm Hg and a mean CST value of 15.57±1.77 mm Hg.

CONCLUSION

Our data suggest that ORA and GAT could be used interchangeably in HS; GAT, ORA and CST could be used interchangeably in KC patients and that GAT provides lower IOP values compared to the other devices in eyes previously submitted to myopic PRK.

Comparison between Corvis and other tonometers in healthy eyes

PURPOSE

To determine the agreement of intraocular pressure (IOP) values in healthy eyes among Goldmann applanation tonometer, dynamic contour tonometer, ocular response analyzer and Corvis. Additionally, to study the relationship between their differences with central corneal thickness (CCT) and corneal curvature (CK).

METHODS

Seventy-six eyes of 76 healthy subjects were examined. Every subject underwent a complete ophthalmic evaluation, a Pentacam scan and three consecutive IOP measurements with each instrument (DCT, GAT, ORA and CST). IOP measurements provided by each device were compared with each other and the differences between them were correlated with morphological parameters obtained by Pentacam (CCT and CK). Statistical analysis was performed using SPSS software, version 18.0.

RESULTS

The mean age of enrolled subjects was 36.8 ± 10.6 years old. The mean IOP measurements that were obtained with GAT, DCT, ORA and CST was 15.62 ± 2.33 mmHg, 17.44 ± 2.51 mmHg, 15.99 ± 3.58 mmHg and 17.24 ± 3.44 mmHg respectively. The mean CCT was 543.63 ± 36.15 μm, the mean CK was 43.35 ± 1.23 D. GAT and ORA provided IOP values not showing a statistical difference; CST and DCT IOP measurements did not show a statistical difference whereas CST provided statistically higher IOP values both than GAT and both ORA.

CONCLUSIONS

According to our data, CST produces IOP values that are notably higher than GAT measures; therefore they cannot be used interchangeably. If CST should be used as the next gold standard, higher IOP values will come to be considered normal.

Phaco-trabeculectomy in controlled, advanced, open-angle glaucoma and cataract: parallel, randomized clinical study of efficacy and safety

BACKGROUND

To examine the efficacy and safety of combined phaco-trabeculectomy in patients with cataract and controlled, open-angle advanced glaucoma and to identify preoperative predictive factors of postoperative glaucoma course.

SETTING

Departments of Ophthalmology, University of Athens, and General Hospital of Lamia, Greece.

METHODS

Prospective, interventional, parallel, cluster (units=examinations), randomized clinical study. 60 patients with visually significant cataract, visual field Mean Deviation (MD) worse than -15.0 dB, and preoperative intraocular pressure (IOP), controlled (consistently below 22 mmHg) on topical medications and with no previous ocular surgery, were randomly allocated (1:1) to phacoemulsification alone or phaco-trabeculectomy group. Intention-to-treat analysis was performed to compare the postoperative outcome and adjusted multivariate longitudinal linear regression analysis was performed to identify predictive factors of the main outcome measures, with postoperative visual field MD change up to two years postoperatively. Participant recruiters and data collectors were masked to group assignment.

RESULTS

31 and 29 patients were randomized to phacoemulsification alone and phaco-trabeculectomy groups, respectively. Patients assigned to the phaco-trabeculectomy group experienced a 1.7 mmHg [95% CI:-3.1 to -0.23] reduction in IOP, a 1.4 dB [95% CI: -0.17 to 2.96] improvement in visual fields MD, a 0.6 [95% CI: -1.2 to -0.05] reduction in the number of glaucoma medications needed postoperatively, while the visual acuity improvement was similar between the two groups. Best predictors for visual field MD: degree of nuclear sclerosis, relative afferent pupilary defect (RAPD), preoperative MD deviation from -19.0 dB and preoperative cup-disc ratio deviation from 0.9. The phacoemulsification group experienced more IOP spikes (>25 mmHg) with Odds Ratio (OR) of 0.34 [95% CI: 0.11-1.02]. No patient lost light perception.

CONCLUSION

Phaco-trabeculectomy in advanced, controlled, open-angle glaucoma patients with cataract results in better postoperative visual field MD with no major adverse events.