Effectiveness of the ICare rebound tonometer in patients with overestimated intraocular pressure due to tight orbit syndrome

Purpose To evaluate the effectiveness of the ICare rebound tonometer in patients with overestimated intraocular pressure (IOP) due to tight orbit syndrome and to identify factors affecting the development of tight orbit syndrome in glaucoma patients. Methods We investigated 84 eyes in 84 glaucoma patients, of which 14 eyes were classified in the tight orbit syndrome group and 70 eyes in the control group. IOP was measured using the ICare tonometer and the Goldmann applanation tonometer (GAT). The demographic data, medical histories, ocular histories, and detailed ocular drug histories of the two groups were compared to identify factors contributing to the development of tight orbit syndrome. Results In the tight orbit syndrome group, the ICare tonometer significantly underestimated the IOP by approximately 8.6 mmHg compared with the GAT. In the control group, the IOP readings of the GAT and the ICare tonometer did not differ significantly. Bland–Altman analysis showed that the mean difference between measurements taken using the GAT and those taken using the ICare tonometer was 2.5 ± 6.3 mmHg. The difference between the GAT and ICare tonometer measurements was greater in the tight orbit syndrome group (8.6 ± 5.3 mmHg) than in the control group (1.3 ± 2.7 mmHg). Multivariate regression analysis revealed that only the use of prostaglandin analogs (PGAs) was associated with the development of tight orbit syndrome. Conclusions The ICare tonometer is a suitable alternative device for use in patients with tight orbit syndrome in whom the IOP may be overestimated with the GAT. The prolonged use of PGAs is significantly associated with the development of tight orbit syndrome.