Abstract: Objective To compare the calculation accuracy of Haigis and SRK/T formulas in patients with pathological myopia who underwent vitrectomy combined with cataract phacoemulsification and IOL implantation. Design Retrospective case series. Participants Twenty-six patients (40 eyes) with pathological myopia who underwent vitrectomy combined with cataract phacoemulsification and IOL implantation in Beijing Tongren Eye Center. Methods The medical records of patients were reviewed. All patients underwent IOL Master 500 examination before the surgeries. Three months postoperatively, the patients underwent optometry. Postoperative spherical equivalent was calculated. The prediction error (PE) and absolute prediction error (APE) of Haigis and SRK/T formulas were calculated. PE means actual postoperative spherical equivalent subtract postoperative diopter predicted by IOL formula. The absolute value of PE is APE. According to the axial length (AL), the study eyes were divided into three groups: AL< 28 mm, 28~30 mm and AL>30 mm. Differences between the indicators of the two formulas in the three groups were analyzed. Main Outcome Measures PE, APE. Results The mean PE values of the two IOL calculation formulas were both positive, suggesting that the calculation results drift towards hyperopia. The PE value of Haigis formula is (0.63±0.93) D and that of SRK/T formula was (0.61±1.17) D with no significant difference. The APE value of Haigis formula was (0.85±0.74) D, and that of SRK/T formula was (0.97±0.89) D with no significant difference. In 26 eyes with axial length ≤30 mm, there was no significant difference in PE or APE value between Haigis and SRK/T formula. In 14 eyes with axial length >30 mm, there was no significant difference on PE values between Haigis and SRK/T formula (t=-0.819, P=0.420). The APE value of Haigis formula was (0.84±0.49) D and that of SRK/T formula was (1.33±1.07) D with a significant difference (t=-2.619, P=0.015). Conclusion Haigis formula was more accurate than SRK/T formula when the axial length was >30 mm in patients with pathological myopia undergoing vitrectomy combined with cataract phacoemulsification and IOL implantation. When the axial length was ≤30 mm, there was no significant difference in the accuracy of Haigis and SRK/T formulas in calculating IOL power. Postoperative diopter shift to hyperopia. (Ophthalmol CHN, 2022, 31: 190-194)

Key words: pathologic myopia, vitrectomy combined with cataract phacoemulsification, intraocular lens power calculation formula