PURPOSE
To test the performance of 4 tonometers in estimating intraocular pressure (IOP) after 3 forms of refractive surgery.
SETTING
Eye Hospital, WenZhou Medical University, China.
DESIGN
Prospective case series.
METHODS
Patients matched for preoperative age, corneal thickness and myopic correction enrolled for femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK), small-incision lenticule extraction (SMILE), or transepithelial photorefractive keratectomy (TransPRK) were included in the study. For each patient, 4 measurements of IOP were obtained preoperative and 3 months postoperative, using the Goldmann applanation tonometer (GAT-IOP), the Dynamic Contour Tonometer (DCT-IOP), corneal-compensated IOP (IOPcc) from the Ocular Response Analyzer, and biomechanically-corrected IOP (bIOP) from the Corvis ST. Overall corneal stiffness was also estimated based on the stiffness parameter (SP-A1) provided by the Corvis ST.
RESULTS
The study included 144 eyes of 144 patients. Among the 3 procedures, the smallest variances between preoperative and postoperative IOP estimates and SP-A1 values were observed with the TransPRK, followed by SMILE and FS-LASIK. In the TransPRK group, no significant differences were observed in both bIOP (-0.18±1.63 mmHg) and DCT-IOP (-0.64±2.34 mmHg), while they were larger and significant in GAT-IOP (-1.78±2.29 mmHg) and IOPcc (-2.77±1.84 mmHg). In FS-LASIK and SMILE groups, while there were similar significant reductions in IOP after surgery, these reductions were still lower in bIOP and DCT-IOP than in GAT-IOP and IOPcc.
CONCLUSIONS
The bIOP and DCT-IOP were the least affected IOP estimates between the 3 refractive surgery procedures considered. It was evident that TransPRK produced significantly smaller reductions in IOP readings than did FS-LASIK and SMILE.