intraocular lens power change after trabeculectomy

purpose: to describe the biometric changes and their effect on intraocular lens (iol) power calculation after trabeculectomy and to compare the accuracy of four formulas namely srk/ii, srk/t, holladay and hoffer q for iol power calculation in these patients. methods: thirty-four eyes of 31 glaucoma patients who were scheduled for primary trabeculectomy were enrolled. a non-contact biometry device (lenstar) was used to measure mean corneal power, axial length, and iol power, calculated with srk/t, srk/ii, holladay and hoffer q formulas, in the day before trabeculectomy and 3 and 6 months postoperatively. postoperative measurements were compared with preoperative values and bland-altman plots were used to investigate the agreement between pre and postoperative calculated iol powers. results: at postoperative months 3 and 6, axial length decreased by 0.14±0.13 and 0.14±0.15 mm (p<0.001) at, respectively and mean corneal power increased by -0.41±0.46 diopter (p<0.001) and -0.27±0.47 diopters (p=0.008), respectively. calculated iol powers ​​were not significantly different from preoperative values (srk/t formula: -0.01±0.64 (p=0.895) at months 3 and -0.2±0.71 diopters (p=0.17) at months 6, srk/ii formula: -0.04±0.76 (p=0.738) at months 3 and -0.2±0.74 diopters (p=0.187) at months 6, holladay formula: 0.1±0.75 (p=0.427) at months 3 and -0.16±0.79 diopters (p=0.319) at months 6, hoffer q formula: 0.09±0.76 (p=0.505) at months 3 and -0.14±0.9 diopters (p=0.442) at months 6). conclusion: after trabeculectomy, the decrease in axial length negated the increase in corneal power which resulted in a non-significant change in postoperative calculated iol powers as compared to preoperative values.