Comparison of surgically induced astigmatism following different glaucoma operations

Abstract

Aim

To compare surgically induced astigmatism (SIA) among glaucomatous eyes treated with trabeculectomy (LEC), EX-PRESS^® shunt (EXP), ab externo trabeculotomy (exLOT), or microhook ab interno trabeculotomy (μLOT).

Subjects and methods

Eighty right eyes of 80 subjects who underwent LEC (n=20), EXP (n=20), exLOT (n=20), or μLOT (n=20) were included. The dataset including the best-corrected visual acuity (BCVA), intraocular pressure (IOP), and keratometry recordings preoperatively and 3 months postoperatively was collected by chart review. The means of the vector magnitude, vector meridian, and arithmetic magnitude of the preoperative and postoperative astigmatism and SIA were calculated. The correlations among the SIA magnitude, postoperative BCVA, and IOP were assessed.

Results

The mean astigmatic arithmetic magnitudes did not differ significantly (P=0.0732) preoperatively among the four groups, but the magnitude was significantly (P=0.0002) greater in the LEC group than the other groups postoperatively. The mean SIA vectors were calculated to be 1.01 D at 56°, 0.62 D at 74°, 0.23 D at 112°, and 0.12 D at 97° for the LEC, EXP, exLOT, and μLOT groups, respectively. The mean SIA arithmetic magnitudes were significantly (P<0.0001) greater in the LEC group than the other groups. Three months postoperatively, the SIA magnitude was correlated positively with the logarithm of the minimum angle of resolution (logMAR) BCVA (r=0.3538) and negatively with the IOP (r=−0.3265); the logMAR BCVA was correlated negatively with the IOP (r=−0.3105).

Conclusion

EXP, exLOT, and μLOT induce less corneal astigmatism than LEC in the early postoperative period.

Keywords:

• SIA
• trabeculectomy
• EX-PRESS shunt
• ab externo trabeculotomy
• microhook ab interno trabeculotomy
• MIGS

Acknowledgments

The microhooks used in this study were codeveloped by Masaki Tanito and Inami & Co., Ltd. and were provided by Inami & Co., Ltd. The authors acknowledge Shiho Kimachi, Jo Fujihara, Shinya Soda, Kaori Ishitobi, and Kumiko Konishi for their support in chart review of the subjects. They also acknowledge the use of the SIA Calculator Version 2.1 (©2010, Dr Saurabh Sawhney, Dr Aashima Aggarwal) in the analysis of data in this study.

Disclosure

The authors report no conflicts of interest in this work.