OBJECTIVE: To investigate the repeatability and reproducibility of a new method for centration analysis after small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK (FS-LASIK).
METHODS: This study comprised 29 eyes treated with SMILE and 24 with FS-LASIK. Decentrations were analyzed using tangential and pachymetry difference maps respectively. Both difference maps were generated with a Scheimpflug tomographer (Pentacam) for each eye, using preoperative and 3-month postoperative scans. Repeatability and reproducibility were evaluated by calculating the intraclass correlation coefficient (ICC), within-subject standard deviation (Sw), and coefficient of repeatability (CR).
RESULTS: ICC, Sw, and CR showed good to excellent repeatability in locating the coordinates of the optical zone (OZ) center on both maps, with values ranging from 0.84 to 0.96, 0.03 to 0.13, and 0.08 to 0.36 respectively. The repeatability of the total decentration from the preoperative corneal vertex on the tangential curvature difference maps( d TC ) and the pachymetry difference maps( d PC ) were moderate and good, respectively. The ICC, Sw, and CR of d TC were 0.63, 0.09, and 0.25, respectively. The ICC, Sw, and CR of d PC were 0.77, 0.10, and 0.28, respectively. The reproducibility of the OZ center measurements was excellent for the tangential difference maps (ICC ≥ 0.97 ) and good for the pachymetry difference maps (ICC ≥ 0.86). ICC, Sw, and CR showed excellent reproducibility of d TC , with values of 0.95, 0.03, and 0.08, respectively. ICC, Sw, and CR showed good reproducibility of d PC , with values of 0.89, 0.06, and 0.17, respectively.
CONCLUSIONS: The centration analysis method used in this study showed good to excellent repeatability and reproducibility in locating the coordinates of the center of the OZ on the tangential and pachymetry difference maps.

OBJECTIVE: To quantify the impact of varying central fluid reservoir depth, lens thickness/mass and the addition of a peripheral fenestration upon scleral lens centration.
METHODS: Ten young, healthy adults participated in a series of repeated-measures experiments involving short-term (90 min) open eye scleral lens wear. Scleral lens parameters (material, back optic zone radius, diameter, back vertex power and landing zone) were controlled across all experiments, and the central fluid reservoir depth (ranging from 144 to 726 μm), lens thickness (ranging from 150 to 1200 μm), lens mass (101-241 mg) and lens design (with or without a single 0.3 mm peripheral fenestration) were altered systematically. Scleral lens decentration was quantified using over-topography maps.
RESULTS: On average, scleral lens centration varied by <0.10 mm over 90 min of wear. Medium and high initial fluid reservoir conditions resulted in 0.17 mm more temporal and 0.55 mm more inferior lens decentration, compared to the low fluid reservoir depth (p < 0.001). Changes in lens thickness or the addition of a peripheral fenestration did not cause clinically significant changes in centration (<0.10 mm on average) when controlling for fluid reservoir depth. Central fluid reservoir depth was the best predictor of horizontal and vertical lens decentration, explaining 62-73% of the observed variation, compared to 40-44% for lens thickness and mass.
CONCLUSIONS: Scleral lens decentration remained relatively stable over 90 min of lens wear. A greater initial central fluid reservoir depth resulted in significantly more lens decentration, particularly inferiorly. Large variations in lens thickness, mass or the addition of a single peripheral fenestration did not substantially affect lens centration.

OBJECTIVE: The fit and optical performance of a scleral lens is affected by the alignment of the landing zone with the underlying ocular surface. The aim of this research was to quantify the effect of landing zone toricity upon scleral lens fitting characteristics (rotation and decentration) and optics (lens flexure) during short-term wear.
METHODS: Scleral lenses with nominal landing zone toricities of 0, 100, 150 and 200 μm were worn in a randomised order by 10 young healthy participants (mean [SD] 24 [7] years) for 30 min, with other lens parameters held constant. Scleral toricity was quantified using a corneo-scleral profilometer, and lens flexure, rotation, and decentration were quantified using over-topography during lens wear. Repeated measures analyses were conducted as a function of landing zone toricity and residual scleral toricity (the difference between scleral and lens toricity) for eyes with \'low\' magnitude scleral toricity (mean: 96 μm) and \'high\' magnitude scleral toricity (mean: 319 μm).
RESULTS: Toric landing zones significantly reduced lens flexure (by 0.37 [0.21] D, p < 0.05) and lens rotation (by 20 [24]°, p < 0.05) compared with a spherical landing zone. Horizontal and vertical lens decentration did not vary significantly with landing zone toricity. These trends for flexure, rotation, and decentration were also observed for eyes with \'low\' and \'high\' magnitude scleral toricity as a function of residual scleral toricity.
CONCLUSIONS: Landing zones with 100-200 μm toricity significantly reduced lens flexure (by ~62%) and rotation (by ~77%) but not horizontal or vertical lens decentration, compared with a spherical landing zone, when controlling for other confounding variables. The incorporation of a toric landing zone, even for eyes with lower magnitude scleral toricity (~100 μm), may be beneficial, particularly for front surface optical designs.

OBJECTIVE: This study aimed to observe the tilt and decentration of multifocal intraocular lens (IOL) with optic capture in Berger space within 2 years after pediatric cataract surgery.
METHODS: This is a prospective observational study. The implantation of multifocal IOL (Tecnis ZMB00) with optic capture in Berger space was performed on 33 patients (48 eyes) with pediatric cataract at Qingdao Eye Hospital. Tilt and decentration of IOL was measured using Scheimpflug system (Pentacam) at 1 month and 2 years postoperatively.
RESULTS: All the multifocal IOLs were successfully implanted in Berger space with optic capture and no visually significant complications were detected during the follow-up. The mean tilt of IOLs was 2.779° ± 0.950° in the vertical plane and 2.399° ± 0.898° in the horizontal plane at 1 month postoperatively, and the mean length of the decentration was 0.207 ± 0.081 mm in vertical plane and 0.211 ± 0.090 mm in the horizontal plane. Compared with 1 month after surgery, the angle of tilt decreased by a mean of 0.192° and decentration increased by a mean of 0.014 mm at the vertical meridian at 2 years postoperatively (P = 0.37 and P = 0.27, respectively), meanwhile, tilt increased by 0.265° and decentration increased by 0.012 mm at the horizontal meridian (P = 0.11 and P = 0.22, respectively).
CONCLUSIONS: The follow-up results suggest the tilt and decentration of multifocal IOL implantation with optic capture in Berger space remain stable in an acceptable range within 2 years after cataract surgery in children above the age of 5.
BACKGROUND: The study was approved by the Ethics Committee of Qingdao Eye Hospital, and registered on Chinese Clinical Trial Registry (ChiCTR identifier: 1900023155).

OBJECTIVE: To evaluate and compare the effect of decentration and tilt on the optical quality of monofocal and trifocal intraocular lenses (IOL).
METHODS: Optical quality of a monofocal IOL (AcrySof IQ SN60WF; Alcon Laboratories, Inc., USA) and a trifocal IOL (AcrySof IQ PanOptix; Alcon Laboratories, Inc., USA) was assessed using an in vitro optical bench (OptiSpheric IOL R&D; Trioptics GmbH, Germany). At apertures of 3.0 mm and 4.5 mm, modulation transfer function (MTF) at spatial frequency of 50 lp/mm, MTF curve and the United States Air Force (USAF) resolution test chart of the two IOLs were measured and compared at their focus with different degrees of decentration and tilt. Optical quality at infinity, 60 cm and 40 cm and the through-focus MTF curves were compared when the two IOLs were centered at apertures of 3.0 mm and 4.5 mm. Spectral transmittance of the two IOLs was measured by the UV-visible spectrophotometer (UV 3300 PC; MAPADA, China).
RESULTS: The SN60WF and the PanOptix filtered blue light from 400 to 500 nm. Both IOLs at the far focus and the PanOptix at the intermediate focus showed a decrease in optical quality with increasing decentration and tilt. The PanOptix demonstrated enhanced optical quality compared to the previous gradient at the near focus at a decentration range of 0.3-0.7 mm with a 3.0 mm aperture, and 0.5 mm with a 4.5 mm aperture, whereas other conditions exhibited diminished optical quality with increasing decentration and tilt at the focus of both IOLs. When the two IOLs were centered, the SN60WF had better optical quality at infinity, while the PanOptix had better optical quality at 60 cm and 40 cm defocus. The optical quality of the SN60WF exceeded that of the PanOptix at far focus, with a 3 mm aperture decentration up to 0.7 mm and a 4.5 mm aperture decentration up to 0.3 mm; this observation held true for all tilts, irrespective of aperture size. As both decentration and tilt increased, the optical quality of the SN60WF deteriorated more rapidly than that of the PanOptix at the far focal point.
CONCLUSIONS: The SN60WF showed a decrease in optical quality with increasing decentration and tilt. Optical quality of the PanOptix at the near focus increased in some decentration conditions and decreased in some conditions, while it showed a decrease at the other focuses with increasing decentration. While tilt only had a negative effect on optical quality. When both IOLs were centered, the PanOptix provided a wider range of vision, while the SN60WF provided better far distance vision. At the far focus, the SN60WF has better resistance to tilt than the PanOptix, but the optical quality degrades more quickly when decentered and tilted.

UNASSIGNED: To determine the differences in myopia control efficiency and corneal reshaping between three different brands of orthokeratology (OK) lenses (Lucid, Euclid, and Alpha).
UNASSIGNED: We retrospectively reviewed subjects who started simultaneously using different brands of OK lenses. For each participant, every 6 months in the 19 months of following, the changes in axial length (AL), horizontal and vertical maximum distances of the treatment zone (HMDTZ and VMDTZ), width of the high convex zone (WHCZ), distance of decentration, and horizontal and vertical components of the decentration vector were measured. The average values of the above data, the average value of the decentration vector (ADV), and the average value of decentration calculated algebraically (ADA) were calculated.
UNASSIGNED: All the three pairs (Lucid (n = 46) vs. Euclid (n = 46): groups Lucid-versus-Euclid-Lucid (LE-L) and LE-E), Lucid (n = 50) vs. Alpha (n = 50): groups LA-L and LA-A), and Euclid (n = 17) vs. Alpha (n = 17): groups EA-E and EA-A) showed good comparability. Regarding the change in AL during 19 months, none of the pairs showed significant differences (LE-L:0.27 ± 0.24 mm, LE-E:0.31 ± 0.24 mm (p = 0.68); LA-L:0.36 ± 0.26 mm, LA-A:0.36 ± 0.27 mm (p = 0.85); EA-E:0.34 ± 0.27 mm, EA-A:0.41 ± 0.28 mm (p = 0.63)). Regarding treatment zone, Lucid showed the largest HMDTZ and VMDTZ (both p < 0.05). Regarding the WHCZ, none of the pairs showed significant differences. For the ADV and ADA, Lucid had more ADV and ADA than Euclid (ADV: LE-L:0.73 ± 0.44 mm, LE-E:0.55 ± 0.45 mm, p < 0.05; ADA: LE-L:0.80 ± 0.41 mm, LE-E:0.63 ± 0.44 mm, p < 0.05), and the remaining pairs showed no significant difference. For the overall cohort with 113 eyes, the change in AL was weakly correlated with both ADV and ADA (both p < 0.05). Regarding the ADV/ADA, all pairs showed no significant differences, indicating equal lens position stability.
UNASSIGNED: After OK, there were no significant differences between the different pairs of the three brands in AL growth, WHCZ, or lens position stability, although Lucid had a larger treatment zone than Euclid and Alpha, and Lucid had more decentration than Euclid. A larger lens decentration were weakly related to less AL growth.

OBJECTIVE: To evaluate the incidence and causes of intraocular lens (IOL) tilt and changes in anterior chamber angle after secondary IOL sulcus implantation following congenital cataract removal.
METHODS: A retrospective observational study was conducted on children who underwent secondary sulcus IOL implantation following pediatric cataract removal in the period from 2017-2020 in Cairo university Hospitals. Children were examined for IOL position, centration, and tilt. Intraocular pressure (IOP) measurement, fundus and gonioscopic examination was performed. Ultrasound biomicroscopy (UBM) was performed on both eyes in children with clinically detected tilt.
RESULTS: Ciliary sulcus secondary IOL implantation was performed in 102 eyes (57 children). IOL tilt was detected clinically in 16 eyes of 14 children (15.7%). UBM showed clinically undetected tilt in the fellow eye in additional 4 eyes. The mean angle of tilt was 12.8 ± 3.9° in clinically detected tilt compared to 7.5 ± 1.2° in UBM detected tilt. Mean anterior chamber depth (ACD) was 2.4 ± 0.5 mm IOP was >21 mmHg in 1.9% of eyes. Narrowing of the anterior chamber angle (ACA) after sulcus implantation occurred in 40% of eyes with open angle. Sulcus proliferations and obliterated sulcus were detected in all 20 eyes. Sommering\'s ring was found in 7 eyes (35%). Axial length, corneal diameter, and presence of persistent fetal vasculature did not affect IOL position.
CONCLUSIONS: The presence of residual lens matter or an obliterated ciliary sulcus is associated with a higher incidence of IOL malposition following ciliary sulcus implantation.

OBJECTIVE: To evaluate the relative positions of modern soft contact lenses (SCLs) relative to the limbus/cornea and the pupil.
METHODS: Sixty images of the anterior eyes of 101 subjects were acquired over 10 s while participants fixated the centre of the camera lens located 33 cm in front of the eye in a well-lit (300 lux) clinic. Custom validated image analysis software was used to locate the boundaries of the contact lenses, pupils and corneas (limbus). Horizontal and vertical relative positions of the contact lens, pupil and limbus were calculated from the fitted boundaries.
RESULTS: The mean (standard deviation) pupil and corneal diameters for all subjects were 3.84 mm, (0.83) and 11.97 mm (0.48), respectively. The mean [95% confidence interval] pupil centre was located 0.28 mm [0.26, 0.30] nasally and 0.07 mm [0.05, 0.10] superiorly to the corneal centre. Consistent with clinical observations, the contact lenses centred accurately relative to the corneal centre both nasally 0.04 mm [0.01, 0.07] and inferiorly -0.01 mm [-0.06, 0.03]. However, regardless of the eye, the contact lens was significantly (p < 0.001) decentred relative to the pupil centre both temporally -0.23 mm [-0.26, -0.20] and inferiorly -0.08 mm [-0.12, -0.04]. Decentration magnitudes were significantly correlated between the right and left eyes.
CONCLUSIONS: Spherical SCLs centred well on the cornea but temporally and inferiorly from the primary line of sight (pupil centre), due to the differences in the location of the pupil and corneal centres. Contrary to some previous reports, there was no evidence that lens optics or material affected lens centration significantly.

Lens dislocation is a significant complication after cataract surgery. Scleral fixation of 3-piece intraocular lens provides favorable visual outcome and can spare patients the need for lens exchange. Two patients presented with dislocated 3-piece lenses implanted over 10 years earlier. Both patients underwent pars plana vitrectomy and dropped lens rescue with scleral fixation. Postoperatively, the lens optic was found flipped nearly 90° at the optic-haptic junctions secondary to fluid-air exchange performed during vitrectomy. Both patients underwent intraocular lens exchange with a four point sclera fixated lens. Our study found that air tamponade is better avoided during rescue of old dislocated 3-piece lens implants. Intraocular lens exchange is preferred, when possible, to avoid complications associated with old dislocated lenses. Larger studies are needed to determine the effect of time on dislocated lens implants materials.

This study aimed to analyze the relationship between visual quality and implantable collamer lenses (ICL) decentration.
Prospective treatment evaluation clinical study METHODS: This prospective study included 119 eyes with ICL implantation. Refractive parameters and ocular aberrations were examined pre- and postoperatively. ICL decentration and higher-order aberrations (HOAs) were evaluated using the OPD-Scan III aberrometer.
At the 1-month follow-up, the mean values for decentration were 0.38 ± 0.19 mm (0.02-0.78). Regarding the position of decentration in right and left eyes, 22.8% and 17.7% were located in the superior nasal section, 0% and 6.5% in the inferior nasal section, 50.9% and 53.2% in the superior temporal section, and 26.3% and 22.6% in the inferior temporal section, respectively. The root mean square values of whole-eye total HOAs, coma, and trefoil had significantly increased. Decentration had a significant negative correlation with variation in the pre- and postoperative trefoils of the whole eye.
ICL decentration had a slightly negative correlation with trefoil and slightly affected visual quality.