Abstract
Purpose :
Trabeculectomy has been established as a safe and effective surgery to control IOP. An important objective of this technique is to adjust the tightness of the scleral flap to establish a balance between fluid under- and over-filtration in order to achieve the target IOP. Intuitive approximations to get trans-operative IOP values is of common practice besides of observing the exit rate of fluid through the scleral flap edges. IC200-tonometry is an accurate instrument to measure IOP in the supine position. The aim of this study is to compare an intuitive manuever to estimate IOP versus IC-200 rebound tonometry during trabeculectomy.
Methods :
In non-consecutive cases in which a trabeculectomy was performed, IOP was measured using an empirical manuever consisting in touching the firmess of the cornea with a cannula by both an experienced glaucoma surgeon (S) and an assisting glaucoma fellow (F). IC-200 rebound tonometry (Icare) was also performed by a third person. IOP estimations were done in random order. IOP guessed values (for the intuitive manuever) and the actual IC-200 (IC) IOP values were verbally manifested at the end of each round of measurements. At least four rounds (R1-R4) of measurements were carried out (one before the paracentesis, two more after the scleral flap was sutured and the anterior chamber was filled with BSS, and one more, prior to the conjunctival closure). Mean value comparisons and correlations were used to analyzed the information. P values of ≤ 0.5 were considered statistically significant.
Results :
Sixteen eyes of 15 patients (mean age 54.6±7.7 years; 10 male and 5 female) were included in the study. Mean baseline IOP was 29.1±8.9 mm Hg. Mean trans-operative values were not statistically significant among each other (R1-IC, 11.5±7.7, R1-S, 10.0±5.8, R1-F, 13.3±7.4; R2-IC, 3.9±1.8, R2-S, 4.7±3.5, R2-F, 5.8±4.5; R3-IC, 8.3±5.8, R3-S, 9.5±5.2, R3-F, 10.5±5.1; R4-IC, 6.8±4.3, R4-S, 8.8±5.1, R4-F, 9.3±6.2). Correlations were weak in R1 and R2, but good and statistically significant in the other two rounds (R3-S, r=0.54, p=0.027; R3-F, r=0.80, p=0.0002; R4-S, r=0.54, p=0.027; R4-F, r=0.76, p=0.016).
Conclusions :
IC-200 rebound tonometry is a feasible technique to be used trans-operatively during trabeculectomy and has potential to be used in a training process in order to improve surgeon’s ability to estimate IOP in the operating room.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.