Tonometry in Corneal Edema after Cataract Surgery: ReboundversusGoldmann Applanation Tonometry

Corneal Edema after Cataract Surgery

This systematic review investigates the prevalence and underlying causes of corneal edema following cataract surgery employing manual phacoemulsification. A comprehensive search encompassing databases such as PubMed, Embase, ProQuest, Cochrane Library, and Scopus was conducted, focusing on variables encompassing cataract surgery and corneal edema. Two independent reviewers systematically extracted pertinent data from 103 articles, consisting of 62 theoretical studies and 41 clinical trials. These studies delved into various aspects related to corneal edema after cataract surgery, including endothelial cell loss, pachymetry measurements, visual performance, surgical techniques, supplies, medications, and assessments of endothelial and epithelial barriers. This review, encompassing an extensive analysis of 3060 records, revealed significant correlations between corneal edema and endothelial cell loss during phacoemulsification surgery. Factors such as patient age, cataract grade, and mechanical stress were identified as contributors to endothelial cell loss. Furthermore, pachymetry and optical coherence tomography emerged as valuable diagnostic tools for assessing corneal edema. In conclusion, this systematic review underscores the link between corneal edema and endothelial cell loss in manual phacoemulsification cataract surgery. It highlights the relevance of factors like patient demographics and diagnostic modalities. However, further research is essential to unravel the complexities of refractive changes and the underlying mechanisms.

[Tonometry: Review and Perspectives]

Reliable and repeated IOP measurement are essential in the diagnosis and treatment of glaucoma. In this first part of this review, besides the physiological basics, contact tonometry will be presented, which is both the first instrumental method with the indentation tonometers and the gold standard with the Goldmann applanation tonometer. Both methods and subsequently developments will be discussed.

Tonometrie: Rückblick und Ausblick (Teil 1)

Der intraokulare Druck (IOD) ist ein wichtiger physikalischer Parameter der Physiologie des Auges. Ein erhöhter IOD wurde früh als Ätiologie für Augenerkrankungen vermutet. In diesem 1. Teil des Beitrags wird neben den physiologischen Grundlagen die Kontakttonometrie vorgestellt, die sowohl die erste instrumentelle Methode mit den Indentationstonometern als auch den Goldstandard mit dem Goldmann-Applanationstonometer darstellt.

Variations of Intraocular Pressure Measured by Goldmann Applanation Tonometer, Tono-Pen, iCare Rebound Tonometer, and Pascal Dynamic Contour Tonometer in Patients With Corneal Edema After Phacoemulsification

PRCIS

Edematous corneas had lower Goldmann applanation tonometer (GAT) intraocular pressure (IOP) compared with other tonometers. A significant, mild negative correlation between central corneal thickness (CCT) and GAT IOP was found in a group of significant edematous corneas with CCT increases of >100 µm.

PURPOSE

To compare the IOP that was randomly obtained with the GAT, Tono-Pen, iCare, and Pascal dynamic contour tonometer in patients with corneal edema after phacoemulsification.

MATERIALS AND METHODS

Corneal edema was quantified by CCT measurement. The agreement between IOP measurements assessed by different instruments was evaluated using Bland-Altman plots. The relationship between CCT and IOP was investigated using the coefficient of correlation. The CCT and IOP were compared between the periods of postsurgical edema and after its resolution.

RESULTS

The mean age of 60 patients was 75.9±7.8 years. CCT increased significantly after surgery, by an average of 96.1±39.9 µm (P<0.001). Relative to the IOPs measured with the GAT in edematous eyes: the mean difference in Tono-Pen IOPs was 4.7 mm Hg; 95% limits of agreement (LOA), -0.3 to 9.6 mm Hg. For iCare, was 2.3 mm Hg; 95% LOA, -2.2 to 6.8 mm Hg. For Pascal dynamic contour tonometer, was 3.0 mm Hg; 95% LOA, -0.4 to 6.5 mm Hg. Edematous corneas had significantly lower GAT IOP than Tono-Pen IOP; 12.3±3.2 versus 16.9±3.1 (P=0.02). Pearson correlation coefficients (r) showed a high correlation between the 4 tonometers in eyes without edema. There was a significant, mild negative correlation between CCT and GAT IOP (r=-0.25, P=0.02) in a group of significant edematous corneas with CCT increases of >100 µm: GAT IOP decreased by 3.1 mm Hg for every 10-µm increase in CCT.

CONCLUSIONS

IOP readings with GAT tended to be lower than those obtained with the other tonometers, especially the Tono-Pen. GAT IOP readings in cases of severe corneal edema should be interpreted with caution.

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.

A comparison of Icare PRO and Tono-Pen XL tonometers in anesthetized children

BACKGROUND

Tonometry in the anesthetized child, vital for evaluating known or suspected glaucoma, remains limited to tonometers capable of supine recording. The Icare PRO measures intraocular pressure (IOP) in the sitting or supine patient. The purpose of this study was to compare Icare PRO and Tono-Pen tonometry during examination under anesthesia in eyes of supine children with normal eyes and glaucoma and/or corneal pathology.

METHODS

In this prospective study of children undergoing examination under anesthesia, IOP was recorded in both eyes with Icare PRO and Tono-Pen immediately after mask anesthesia induction, with instrument order randomized.

RESULTS

A total of 100 eyes of 50 children (median age, 58 months) were included. IOP range was 6-50 mm Hg by Icare PRO and 6-53 mm Hg by Tono-Pen. Mean IOP measured by Tono-Pen (18.9 ± 7.5) was higher than that measured by Icare PRO (16.7 ± 7.1 mm Hg) by 2.2 mm Hg (P < 0.001). The presence of corneal edema was associated with IOP measurements higher by Tono-Pen than by Icare PRO (mean difference, 8.4 mm Hg). When eyes with corneal edema were excluded from analysis, there was no correlation between central corneal thickness and the difference in IOP between the two instruments.

CONCLUSIONS

IOP in eyes of supine children under anesthesia measured approximately 2 mm Hg higher by Tono-Pen than Icare PRO and this difference was greater in eyes with frank corneal edema. Icare PRO may become a valuable tool for tonometry in supine infants and children, but a confirmatory test should be considered in eyes with corneal edema.