The utility of Diaton tonometer measurements in patients with ocular hypertension, glaucoma, and glaucoma tube shunts: A preliminary study for its potential use in keratoprosthesis patients

Purpose: Glaucoma is common in patients with the Boston type 1 keratoprosthesis (KPro). Because of the inability to perform corneal applanation in KPro patients, digital palpation is currently the mainstay for assessment of intraocular pressure (IOP). The purpose of this study was to determine whether the Diaton tonometer, which estimates IOP through transpalpebral scleral indentation, can reasonably detect high IOP when compared with Goldmann applanation tonometry (GAT) in patients with ocular hypertension, glaucoma, or glaucoma tube shunts. If reliable in these patients, it may be helpful in patients with KPros. Materials and Methods: We prospectively measured IOP using GAT and Diaton transpalpebral tonometry (DTT) on the upper and lower eyelids in 87 eyes of 57 adult participants with ocular hypertension and glaucoma, several of whom had glaucoma tube shunts. Results: The correlation coefficient between GAT and DTT on the upper eyelid was 0.64 (P<0.0001). For detecting an IOP of >21mm Hg as measured by GAT, DTT on the upper eyelid had a sensitivity and specificity of 65% and 81%, respectively. The positive and negative predictive values were 74% and 73%, respectively. Bland-Altman analysis demonstrated limits of agreement of 2.0±19.5mm Hg for GAT versus DTT on the upper eyelid. The presence of a tube shunt did not significantly affect the results. Conclusions: Diaton tonometry has a large margin of error compared with GAT in patients with ocular hypertension, glaucoma, and glaucoma tube shunts. However, given the current lack of an objective and quantitative method of IOP measurement in KPro patients, Diaton tonometry may be useful in this population as a supplement to digital palpation.