Comparison of Intraocular Pressure Measurements with Goldmann Applanation Tonometry, iCare, and Tono-Pen in Young Children with Anterior Segment Abnormalities Under General Anesthesia.

Abstract

Background: In young patients with suspected elevated intraocular pressure (IOP), examinations under general anesthesia remain the gold standard. This study aimed to compare the reliability of Goldmann applanation tonometry (Perkins), iCare rebound tonometry, and the Tono-Pen in young children under general anesthesia in a clinical setting. Methods: This retrospective study included patients under six years of age requiring an ophthalmic examination under general anesthesia. IOP measurements were performed using all three devices, and central corneal thickness (CCT) was recorded for each patient. Results: A total of 38 eyes of 19 children (mean age, 1.8 ± 2.1 years) were included. IOP values of all three devices ranged from 5 to 43 mmHg, with a mean CCT of 645.6 ± 135 µm. The Tono-Pen recorded significantly higher IOP values than the Perkins tonometer (15.2 ± 5.5 mmHg vs. 11.1 ± 4.8 mmHg; p = 0.002), while no significant differences were observed between Perkins and iCare. CCT was significantly correlated with iCare (r = 0.344, p = 0.032) and the Tono-Pen (r = 0.519, p = 0.001) but not with Perkins (r = 0.247, p = 0.129). Bland-Altman analysis showed a significant slope for inter-device differences, but when excluding IOP values >25 mmHg, the slope was no longer significant. Conclusions: Among the devices tested, the Perkins tonometer was the least affected by other parameters such as CCT and IOP values in young patients under general anesthesia, particularly when IOP exceeded 25 mmHg or corneal thickness was increased. In patients with normal corneas and IOP below 25 mmHg, iCare provided comparable accuracy to Perkins, while the Tono-Pen consistently overestimated IOP compared to both devices.