Korean J Ophthalmol.  2019 Feb;33(1):70-81. 10.3341/kjo.2018.0085.

Analysis of Positional Relationships of Various Centers in Cataract Surgery

  • 1Department of Ophthalmology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea. hwtchah@amc.seoul.kr


To analyze the positional relationships of various centers in patients undergoing femtosecond laser-assisted cataract surgery (FLACS).
The locations of the pupil center (PC), limbal center (LC) and lens center were analyzed in each patient using optical coherence tomography during FLACS in 35 eyes of 35 patients. Using the preoperative corneal aberrometry device, angle kappa and the location of the visual axis (VA) were calculated. After acquiring the relative horizontal and vertical coordinates of each center, the distance and location among each center were compared. The relative location and distance of each center were statistically evaluated.
The distance from the PC to the lens center was 0.147 ± 0.103 mm, that from the LC to the lens center was 0.205 ± 0.104 mm, and that from the VA to the lens center was 0.296 ± 0.198 mm. The distance from the PC to the VA was 0.283 ± 0.161 mm, that from the LC to the VA was 0.362 ± 0.153 mm, and that from the lens center to the VA was 0.296 ± 0.198 mm. Among the various centers, the PC was the closest to the lens center, whereas the LC and VA were the farthest. Based on the location of the lens center, the PC, LC, and VA exhibited differences in the X and Y coordinate positions (vertical p = 0.004, horizontal p < 0.001). Among them, the LC was significantly inferior and temporal compared to the PC (vertical p = 0.026, horizontal p = 0.023). Based on the location of the VA, the respective locations of the PC, LC and lens center in two dimensions did not significantly differ (vertical p = 0.310, horizontal p = 0.926).
This study demonstrated the positional and locational relationships between the centers regarding FLACS. The locations of the PC, LC, and VA were different from the lens center with the PC being the closest. Surgeons should be aware of these positional relationships, especially in FLACS.


Angle kappa; Lens center; Limbal center; Pupil center; Visual axis

MeSH Terms

Tomography, Optical Coherence


  • Fig. 1 Location of each center. (A) Lens center, (B) pupil center, and (C) limbal center.

  • Fig. 2 Extrapolation of anterior and posterior capsular lines in the crystalline lens.

  • Fig. 3 Calculation of the distances between the pupil, limbal and lens centers. Pixels for each center were acquired using ImageJ software. (A) Lens center, (B) pupil center, and (C) limbal center.

  • Fig. 4 Location of the pupil center and visual axis on OPD scan III in a pharmacologically dilated state. The blue and pink centers are the photopic and mesopic pupil centers, respectively, and the large central plus sign represents the visual axis. PDist and MDist denote the distance between the pupil center and the visual axis in the photopic and mesopic states, respectively.

  • Fig. 5 Distance between centers. (A) Distance between centers and the lens center and (B) distance between centers and the visual axis (VA). PC = pupil center; LC = limbal center. *Statistically significant.

  • Fig. 6 Location of the pupil, limbal center and visual axis relative to the lens center. (A) Relative pupil center location, (B) relative limbal center location, and (C) relative visual axis location.

  • Fig. 7 Location of the pupil, limbal and lens centers relative to the visual axis. (A) Relative pupil center location, (B) relative limbal center location, and (C) relative lens center location.


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