Purpose: The toric-type lens has been added to the list of low-power segmental intraocular lenses (IOLs); however, this lens known to rarely rotate significantly after implantation. Accordingly, in this study, the postoperative rotation angle of patients implanted with normal low-power segmental IOLs with the same shape as that of the toric lens was compared between horizontal and vertical fixations.
Subjects and methods: Among the eyes implanted with low-power segmental IOLs (LS-313 MF15, Santen) fixed in the capsule, 84 eyes of 55 patients fixed in the horizontal direction (H group) and 84 eyes of 47 patients fixed in the vertical direction (V group) were included in the study. Still images at the end of surgery captured from surgery videos was superimposed on the images of the anterior segment after mydriasis at ≥3 days after surgery and, the angles of intracapsular rotation after the end of surgery were measured and compared between the two groups.
Results: The corneal refractive power (mean±standard deviation) was 44.0±1.6 D and 44.1±1.9 D, axial length of the eye was 23.6±1.1 mm and 24.0±1.5 mm, IOL power was 19.3±2.9 D and 18.3±3.7 D, anterior chamber depth was 3.4±2.3 mm and 3.1±0.4 mm, corneal diameter was 11.5±0.8 mm and 11.5±0.8 mm, central lens thickness was 4.6±0.6 mm and 4.8±2.0 mm, lens capsule diameter was 10.3±0.2 mm and 10.3±0.2 mm, and continuous curvilinear capsulorrhexis area was 27.1±3.8 mm² and 27.4±3.2 mm², for the H and V groups, respectively, with no significant differences between the two groups in all measurements. Although no significant differences were found between the two groups in terms of postoperative rotation angle, (rotation angles: 7.9±15.4° and 4.4±4.8° for the H and V groups, respectively), rotation of ≥20° was significantly more common in the H group, with seven and zero eyes in the H and V groups, respectively (p=0.0137; Fisher exact test).
Conclusion: This study found no significant differences in the postoperative rotation angles of low-power segmental IOLs between horizontal and vertical fixations, but the frequency of significant rotations was found to be higher when IOL was fixed in the horizontal direction.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 127: 844-849,2023.