Influence of a Capsular Tension Ring on Capsular Bag Behavior of a Plate Haptic Intraocular Lens: An Intraindividual Randomized Trial.

PURPOSE: To evaluate the influence of a capsular tension ring (CTR) on rotational stability, decentration, tilt, and axial stability of an 11.0-mm plate haptic intraocular lens (IOL). DESIGN: Intraindividual, randomized, double-masked, controlled clinical trial. PARTICIPANTS: Patients scheduled for sequential same-day bilateral cataract surgery. METHODS: All patients were randomized to receive a CTR and a plate haptic IOL in one eye and a plate haptic IOL in the fellow eye only. Intraocular lens axis assessment was performed at the end of surgery, 1 hour, 1 week, 1 month, and 6 months using a high-precision evaluation method. Decentration and tilt of the crystalline and pseudophakic lenses were assessed before surgery and at 1 week and 6 months using an anterior segment OCT. MAIN OUTCOME MEASURES: Rotational stability from the end of surgery to 6 months and at all follow-up visits, decentration and tilt at 6 months, and differences in axial shift between 1 week and 6 months. RESULTS: One hundred thirty eyes of 65 patients were included in the study. Absolute rotation from the end of surgery to 6 months was 2.8 ± 3.9° and 3.2 ± 5.3° for the CTR and control groups, respectively (P = 0.613). Intraocular lens decentration and IOL tilt at 6 months were 0.29 ± 0.1 mm and 0.24 ± 0.1 mm and 6.7 ± 2.8° and 5.6 ± 1.6° for the CTR and control groups, respectively (P = 0.058; P < 0.01). A posterior IOL shift of 0.31 ± 0.31 mm and 0.19 ± 0.14 mm was observed in the CTR and control groups, respectively. CONCLUSIONS: Concomitant implantation of a CTR and a plate haptic IOL did not improve the overall rotational stability of the IOL compared with the control group. Against expectations, higher values of decentration, tilt, and axial shift were observed in the CTR group. The simultaneous use of a CTR and a plate haptic IOL in the absence of zonular weakness at the time of cataract surgery should be considered with caution. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Effect of decentration and tilt on the in vitro optical quality of monofocal and trifocal intraocular lenses.

PURPOSE: 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.

Prediction of IOL decentration, tilt and axial position using anterior segment OCT data.

BACKGROUND: Intraocular lenses (IOLs) require proper positioning in the eye to provide good imaging performance. This is especially important for premium IOLs. The purpose of this study was to develop prediction models for estimating IOL decentration, tilt and the axial IOL equator position (IOLEQ) based on preoperative biometric and tomographic measures. METHODS: Based on a dataset (N = 250) containing preoperative IOLMaster 700 and pre-/postoperative Casia2 measurements from a cataractous population, we implemented shallow feedforward neural networks and multilinear regression models to predict the IOL decentration, tilt and IOLEQ from the preoperative biometric and tomography measures. After identifying the relevant predictors using a stepwise linear regression approach and training of the models (150 training and 50 validation data points), the performance was evaluated using an N = 50 subset of test data. RESULTS: In general, all models performed well. Prediction of IOL decentration shows the lowest performance, whereas prediction of IOL tilt and especially IOLEQ showed superior performance. According to the 95% confidence intervals, decentration/tilt/IOLEQ could be predicted within 0.3 mm/1.5°/0.3 mm. The neural network performed slightly better compared to the regression, but without significance for decentration and tilt. CONCLUSION: Neural network or linear regression-based prediction models for IOL decentration, tilt and axial lens position could be used for modern IOL power calculation schemes dealing with 'real' IOL positions and for indications for premium lenses, for which misplacement is known to induce photic effects and image distortion.

Comparative visual outcomes of the first versus second eye following small-incision lenticule extraction (SMILE).

BACKGROUND: This study aimed to compare the visual outcomes of the first operated eyes with those of the second operated eyes following small-incision lenticule extraction (SMILE). METHODS: A total of 202 patients (404 eyes) underwent SMILE using the tear film mark centration method for myopia and myopic astigmatism correction. Baseline characteristics, objective optical quality, decentered displacement, induced corneal aberrations, and modulation transfer function (MTF) values were assessed. Linear regression analyzed the relationship between decentration and visual quality parameters, including corneal aberrations and MTF values. RESULTS: No significant difference was observed in objective visual quality, efficacy, and safety indexes between the two groups (all P > 0.05). The average decentered displacement for the first and second surgical eyes was 0.278 ± 0.17 mm and 0.315 ± 0.15 mm, respectively (P = 0.002). The horizontal coma in the first surgical eyes were notably lower than in the second (P = 0.000). MTF values at spatial frequencies of 5, 10, 15, and 20 cycles/degree (c/d) were higher in the first surgical eyes compared to the second (all P < 0.05). Linear regression indicated that high-order aberrations (HOAs), root mean square (RMS) coma, spherical aberration, horizontal coma, vertical coma, and eccentric displacement were all linearly correlated. Furthermore, MTF values exhibited a linear relationship with eccentric displacement across these spatial frequencies. CONCLUSIONS: There was no discernible difference in visual acuity, efficacy, or safety between the two operated eyes. Nonetheless, the first operated eyes exhibited reduced decentered displacement and demonstrated superior outcomes in terms of horizontal coma and MTF values compared to the second operated eyes following SMILE. The variations in visual quality parameters were linearly correlated with decentered displacement.

The effect of lens and fitting characteristics upon scleral lens centration.

PURPOSE: 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. CONCLUSION: 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.

The effect of landing zone toricity on scleral lens fitting characteristics and optics.

PURPOSE: 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. CONCLUSION: 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.

On-eye centration of soft contact lenses.

PURPOSE: 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.

An analysis of the factors involved in IOL decentration after phacoemulsification using CASIA 2 anterior segment optical coherence tomography.

PURPOSE: To evaluate the magnitude of IOL transversal shift (ITS) after phacoemulsification and to analyse the factors contributing to IOL decentration and ITS. METHODS: 94 consecutive patients who underwent cataract surgery and IOL implantation was enrolled. Each patient underwent anterior segment optical coherence tomography with CASIA 2 (Tomey, Nagoya, Japan) to assess crystalline lens decentration, thickness and diameter seven days preoperatively and at one and sixty days postoperatively. Univariate and multivariate linear regression analysis were performed to evaluate the determinants of ITS and final decentration. RESULTS: The preoperative crystalline lens diameter was associated with the ITS and with the IOL final decentration. A positive association between the final IOL decentration and the first post-surgical day decentration was found (p < 0.0001). CONCLUSION: Greater crystalline lens diameter was associated with greater decentration and with greater ITS. Day-one IOL decentration seems to be the main determinant of final IOL decentration.

Observation on the tilt and decentration of multifocal intraocular lens with optic capture in Berger space for pediatric cataract.

PURPOSE: 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. TRIAL REGISTRATION: The study was approved by the Ethics Committee of Qingdao Eye Hospital, and registered on Chinese Clinical Trial Registry (ChiCTR identifier: 1900023155).

Short-term clinic observation of misalignment and rotational stability after implantable collamer lens implantation.

PURPOSE: We aimed to investigate misalignment (tilt and decentration) and rotational stability of the implantable collamer lens V4c 6 months after implantation and to explore the potential risk factors associated with postoperative misalignment and rotation. METHODS: A total of 36 eyes of 36 patients with high myopia and myopic astigmatism who underwent implantable collamer lens V4c implantation were included in this study. Tilt, decentration, and rotation of the implantable collamer lens were assessed postoperatively at l week, 1 month, 3 months, and 6 months. Correlation analysis was used to identify the potential risk factors for implantable collamer lens tilt, decentration, and rotation at 6 months postoperatively. Higher-order aberration was measured to evaluate the effect of implantable collamer lens misalignment on visual quality at pupil diameters of 4.0 mm and 6.0 mm. RESULTS: The tilt and decentration at the last follow-up were 2.43 ± 1.35° and 0.278 ± 0.160 mm, respectively. There was a significant positive correlation between tilt and decentration (r = 0.31, P = 0.046). No significant correlation was detected between implantable collamer lens decentration and internal higher-order aberrations (P > 0.05). The degree of implantable collamer lens rotation (3.11 ± 2.00°) was significantly associated with the vault (r = - 0.422, P = 0.01), while it was positively associated with the preoperative anterior chamber depth (r = 0.36, P = 0.034). No significant correlation was found between postoperative astigmatism and rotation (r = - 0.07, P = 0.351). CONCLUSIONS: The implantable collamer lens V4c provides relatively stable misalignment and rotation after implantation. The ICL lens vault is a potential risk factor for postoperative implantable collamer lens rotation. The absolute value of decentration and tilt was relatively small, which showed no correlation with internal higher-order aberration in short-term observation.

Influence of decentration of plate-haptic toric intraocular lens on postoperative visual quality.

BACKGROUND: To evaluate the influence of decentration of plate-haptic toric intraocular lens (IOLs) on visual quality. METHODS: This study enrolled 78 eyes of 78 patients. Patients in group A were implanted with toric IOLs, and patients in group B were implanted with monofocal IOLs. All patients were divided into group A1 and B1 (decentration below 0.3 mm) and group A2 and B2 (decentration above 0.3 mm). The uncorrected distance visual acuity (UDVA), best corrected visual acuity (BCVA), modulation transfer function cutoff (MTF cutoff), objective scatter index (OSI), strehl ratio (SR), optical interference and patients' satisfaction were measured in different pupils at three months postoperatively. The associations between decentration and visual quality were analyzed by Spearman correlation. RESULTS: There were no significant differences in UDVA, BCVA, MTF cutoff, OSI, SR, optical interference and patients' satisfaction among subgroups. The differences in decentration between groups A and B were not statistically significant. In group A2, the total higher order aberrations (tHOAs) at pupil sizes of 3 mm (P = 0.046), 5 mm (P = 0.014), spherical aberrations at pupil sizes of 3 mm (P = 0.011), 4 mm (P = 0.014), 5 mm (P = 0.000), secondary astigmatism at pupil sizes of 3 mm (P = 0.002), 4 mm (P = 0.005) were higher than in group B2. Compared to group A1, group A2 had higher spherical aberrations at pupil sizes of 4 mm (P = 0.042), 5 mm (P = 0.001), 6 mm (P = 0.038), secondary astigmatism at pupil sizes of 3 mm (P = 0.013), 4 mm (P = 0.005), 6 mm (P = 0.013). Group B2 has higher coma and secondary astigmatism than group B1 at 6-mm pupil (P = 0.014, P = 0.045). Significant positive correlations were found between spherical aberrations and the decentration of group A1 and A2 at 6-mm pupils. CONCLUSION: The decentration above 0.3 mm negatively affected visual quality due to increased tHOAs, spherical aberrations, coma and secondary astigmatism aberrations, the influence become larger with increasing pupil diameter. And toric IOLs are more affected by decentration than monofocal IOLs.

Comparison of sutureless intrascleral fixation and sutured scleral fixation for the treatment of dislocated intraocular lenses.

BACKGROUND: To compare the outcomes of sutured transscleral fixation and sutureless intrascleral fixation for the treatment of a dislocated intraocular lens (IOL). METHODS: Thirty-five eyes of 35 patients who required IOL repositioning surgery due to IOL dislocation were included in this retrospective study. Sixteen eyes underwent two-point sutured transscleral fixation, eight eyes underwent one-point sutured transscleral fixation, and 11 eyes underwent sutureless intrascleral IOL fixation. The patients were followed for ≥ 12 months after repositioning surgery, and their postoperative outcomes were recorded and analyzed. RESULTS: The major cause of IOL dislocation was ocular blunt trauma (19/35, 54.3%). The mean corrected distance visual acuity (CDVA) improved significantly after IOL repositioning (P = 0.022). The mean postoperative change in endothelial cell density (ECD) was - 4.5%. There were no significant differences in the changes in CDVA or ECD among the three groups with different repositioning techniques (both P > 0.1). The mean vertical tilt of the IOLs in all enrolled patients was significantly greater than the horizontal value (P = 0.001). The vertical tilt was greater in the two-point scleral fixation group than that in the sutureless intrascleral fixation group (P = 0.048). The mean decentration values in the one-point scleral fixation group in the horizontal and vertical directions were greater than those in the other two groups (all P < 0.01). CONCLUSION: All three IOL repositioning techniques resulted in favorable ocular prognosis.

Comparison of visual performance between peripheral gradient high-addition multifocal soft contact lenses and orthokeratology.

PURPOSE: The aim of this study was to evaluate the short-term effects of peripheral gradient high-addition multifocal soft contact lenses (MFSCLs) and orthokeratology (Ortho-K lenses) on visual performance in myopic children. METHODS: Thirty myopic children participated in this prospective study. Each participant wore different sets of lenses in the following sequence: single-vision spectacles (SVSPs) as a control, MFSCLs and Ortho-K lenses. Ocular aberrations, topography, high-contrast visual acuity (HCVA), low-contrast visual acuity (LCVA) and accommodation of the right eye were measured with each type of correction on a different day. RESULTS: Compared with SVSPs, high-addition MFSCLs and Ortho-K lenses significantly increased all items of aberrations (all p < 0.05) except trefoil (p = 0.17). MFSCLs induced less coma, root mean square of the third-order aberration (RMS3) and higher order aberrations than Ortho-K lenses (all p < 0.05). No significant difference in HCVA was found across the three correction types (F = 1.19, p = 0.39). In terms of LCVA, MFSCLs performed significantly poorer than SVSPs (difference, 0.16 logMAR; p = 0.001) and slightly worse than Ortho-K lenses (difference, 0.08 logMAR; p = 0.35). No significant difference in decentration was found between the two types of contact lenses, and no associations were observed between decentration and visual acuity at both high- and low-contrast levels (all p > 0.05). For MFSCLs, decentration was positively related to coma (r = 0.43, p = 0.02) and RMS3 (r = 0.44, p = 0.02), which was not the case for Ortho-K lenses. Accommodative facility was worse with MFSCLs than Ortho-K lenses (p = 0.001). CONCLUSION: Multifocal soft contact lenses differed from Ortho-K lenses in aberration profile and LCVA, although decentration was similar. Decentration <1 mm had minimal influence on both HCVA and LCVA for either type of correction, but significantly increased third-order aberrations for MFSCLs, but not Ortho-K lenses.

Postoperative intraocular lens stability following cataract surgery with or without primary posterior continuous curvilinear capsulorrhexis: an intra-individual randomized controlled trial.

PURPOSE: To evaluate the effect of primary posterior continuous curvilinear capsulorrhexis (PPCCC) on the positional stability of IOLs. METHODS: This study is a prospective intra-individual comparative randomized controlled trial including 31 patients (62 eyes). Eyes of the same patient were randomly assigned to the PPCCC group (18 right eyes and 13 left eyes) or group without PPCCC (NPCCC group). Eyes in both groups were implanted with a one-piece foldable hydrophobic acrylic IOL via routine cataract surgery. Patients in the PPCCC group underwent additional manual PPCCC before IOL implantation. Examinations were performed 1 day, 1 week, 1 month and 3 months postoperatively. IOL tilt (x, y), decentration (x, y), anterior chamber depth (z) and refractive prediction error data were collected and analyzed with Pentacam. RESULTS: Postoperatively, the range of IOL position change over 3 months in PPCCC group was comparable to NPCCC group, which indicated smaller value in every tilt and decentration index. PPCCC eyes showed comparable tilt and decentration with NPCCC eyes in this study endpoint: mean tilt (x, y), decentration (x, y) and anterior chamber depth (ACD) were 1.04 ± 0.56°, 0.90 ± 0.64°, 0.239 ± 0.140 mm, 0.233 ± 0.133 mm and 4.01 ± 0.32 mm, respectively, in the PPCCC group vs. 1.09 ± 0.76°, 1.10 ± 0.82°, 0.252 ± 0.153 mm, 0.244 ± 0.155 mm and 4.01 ± 0.38 mm, respectively, in the NPCCC group. Refractive prediction error in the PPCCC group demonstrated a mild hyperopic shift vs. the NPCCC group (0.13 ± 0.50 vs. 0.05 ± 0.39; p = 0.208), and corrected distance visual acuity (CDVA) did not differ between the two groups (0.027 ± 0.014 vs. 0.059 ± 0.185; p = 0.377). CONCLUSIONS: Comparable IOL tilt, decentration, ACD and refractive prediction error were observed in PPCCC eyes with that underwent routine cataract surgery. Little IOL position fluctuation and good visual acuity were shown in PPCCC group over time. TRAIL REGISTRATION: The study was registered at the Chinese Clinical Trial Register Center on May 27th, 2020 (protocol code ChiCTR2000033304, 27/05/2020).

Effects of tilt and decentration of Visian Implantable Collamer Lens (ICL V4c) on visual quality: an observational study.

BACKGROUND: The central hole of the Visian Implantable Collamer Lens (ICL V4c) provides a reference to observe its tilt or decentration. This study aimed to investigate the tilt and decentration effects of ICL V4c on visual quality after implantation. METHODS: A total of 135 eyes from 69 patients who underwent ICL V4c implantation were included in this study. Evaluation of uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and aberrations were performed 6-months postoperatively. The anterior segment parameters were collected using CASIA2 anterior segment-optical coherence tomography, tilt and decentration of ICL V4c were analyzed using MATLAB software. All patients received questionnaires to investigate the visual quality postoperatively. RESULTS: The safety and effectiveness were 1.18 ± 0.17 and 1.11 ± 0.18, respectively. No significant changes were observed regarding higher-order and spherical aberrations after the operation; however, coma and trefoil significantly increased compared to preoperative values. The average total decentration and tilt was 0.21 ± 0.12 mm and 2.54 ± 1.00°, respectively. Horizontal, vertical, and total values of tilt and decentration were not significantly associated with postoperative CDVA, UDVA, and aberrations. The most common visual symptom was halo, and 97.04% of patients had a satisfaction score ≥ 8. The total or horizontal tilt was significantly positively correlated with the frequency, severity, and bothersome scores from the questionnaires. CONCLUSIONS: ICL V4c implantation can obtain high visual quality and patient satisfaction. Although the degree of tilt and decentration after ICL V4c implantation was small, a positive effect on subjective visual quality was observed.

Tilt and decentration of posterior and anterior iris-claw intraocular lenses: a pilot study using anterior segment optical coherence tomography.

BACKGROUND: Information on the centration and tilt of iris-claw intraocular lenses (IC-IOLs) is limited. In this study, we tested the capacity of an anterior segment optical coherence tomography (AS-OCT) instrument to measure decentration and tilt of anterior and posterior IC-IOLs through an integrated software. METHODS: The present observational, cross-sectional study was conducted at University Eye Clinic of Parma (Parma, Italy). The CASIA2 swept-source AS-OCT (Tomey Corp.) was used to measure the tilt and decentration of posterior and anterior IC-IOLs in patients implanted at least 6 months in advance. After failure with full-automation, semi-manual IOL tracing was applied. In-the-bag (IB) contralateral IOLs, when present, were measured automatically. The Bland-Altman method was used to evaluate the agreement between repeated measurements (2 images for each study eye). The amount and direction of tilt and decentration were recorded and plotted into polar charts for evaluation. RESULTS: A total of 21 patients were included: 14 with posterior and 7 with anterior IC-IOL fixation. In 17 eyes (81%), the AS-OCT provided a repeatable measurement of tilt and decentration. All contralateral eyes with IB IOL were automatically measured. The median decentration was 0.67 mm, 0.24 mm, and 0.24 mm in posterior IC-IOLs, anterior IC-IOLs, and IB IOLs group, respectively. The median tilt was 5.0°, 5.6°, and 5.6° for posterior IC-IOLs, anterior IC-IOLs, and IB IOLs, respectively. Tilt direction was mainly temporal, while decentration was inferior-temporal with posterior IC-IOLs and scattered with anterior IC-IOLs and IB IOLs. CONCLUSIONS: The semi-manual tracing function of the CASIA2 AS-OCT provides repeatable and affordable measurements of the decentration and tilt of IC-IOLs in both the anterior and posterior chamber. Data from the former group were similar to the IB group.

The treatment zone decentration and corneal refractive profile changes in children undergoing orthokeratology treatment.

BACKGROUND: To confirm the association between treatment-zone (TZ) decentration and axial length growth (ALG) in children who underwent orthokeratology; and to explore the association between TZ decentration and relative corneal refractive power (RCRP) profile, which was known to be significantly associated with ALG retardation. METHODS: Four hundred myopic children of age 12 years participated in the study, with 200 wearing orthokeratology lenses and the other 200 wearing single-vision spectacle as the controls. Cycloplegic refraction was performed at baseline. Axial length was measured at baseline and 12 months after initial lens wear, and ALG was defined as the difference. In the ortho-k group, TZ decentration and the RCRP map were calculated from the topography map obtained at the 12-month visit. RCRP were summed within various chord radii from the cornea center, and the association to TZ decentration, spherical equivalent (SE), ALG were analyzed with linear regressions. RESULTS: Compared to the controls, children wearing orthokeratology lenses had significantly smaller ALG over 1 year (0.1 ± 0.15 mm vs. 0.32 ± 0.17 mm, p < 0.001). ALG was significantly and negatively associated with summed RCRP within the central cornea of 2 mm in radius. The mean TZ decentration was 0.62 ± 0.25 mm, and the mean direction was 214.26 ± 7.39 degrees. ALG was negatively associated with the TZ decentration magnitude (p < 0.01), but not the direction (p = 0.905). TZ decentration caused an asymmetrical distribution of the RCRP with the nasal side plus power shifting towards the corneal center. For chord radius ranging 1-2 mm, the association between TZ decentration and the summed RCRP were significant, and the proportion of variance accountable increased with chord radius. For chord radius beyond 1.5 mm, the association between baseline spherical equivalent (SE) and summed RCRP was significant. The portion of variance accountable by SE increased and peaked in 2.5 mm chord radius. CONCLUSIONS: A larger TZ decentration was associated with a larger summed RCRP in the central cornea. It may be one of the possible reasons why TZ decentration is beneficial to retarding myopia progression.

The effect of orthokeratology treatment zone decentration on myopia progression.

BACKGROUND: This study aimed to compare the changes in the axial length (AL) in myopic children that wear centered and decentered orthokeratology (Ortho-K). METHODS: This retrospective study included 217 subjects who were treated with an Ortho-K lens for >12 months. The subjects were divided into three groups based on the magnitude of the Ortho-K lens treatment zone decentration: mildly, moderately, and severely decentered groups. Distance and direction of treatment zone decentration were calculated using software that was developed in-house. The AL changes in different groups were compared. RESULTS: Based on the distance of the treatment zone decentration, 65 children (65 eyes) were included in the mildly decentered group, 114 children (114 eyes) in the moderately decentered group, and 38 children (38 eyes) in the severely decentered group. The mean decentration distance in the three groups was 0.35 ± 0.11 mm, 0.71 ± 0.13 mm, and 1.21 ± 0.22 mm, respectively. The mean AL increase in the three groups after 12 months of Ortho-K lens wear was 0.24 ± 0.21 mm, 0.23 ± 0.18 mm, and 0.19 ± 0.20 mm, respectively. There were no significant differences in AL changes among the three groups. CONCLUSIONS: Ortho-K lens decentration is common in clinical practice. The AL change after Ortho-K lens wear was not significantly different in subjects with different magnitudes of Ortho-K lens decentration. Fitting the Ortho-K lens in the properly centered zone is recommended to ensure the safety of Ortho-K lens wear and to maintain visual quality.

Treatment zone decentration promotes retinal reshaping in Chinese myopic children wearing orthokeratology lenses.

PURPOSE: To investigate whether the treatment zone (TZ) decentration in orthokeratology (OK) lenses affects retinal expansion in Chinese children with myopia. METHODS: Children aged 8 to 13 years (n = 30) were assessed over 13 months comprising 12 months of OK lens wear followed by discontinuation of lens wear for 1 month. Corneal topography was measured at 0, 1, 3, 6, 9, 12 and 13 months. TZ decentration of the OK lens was calculated, and subjects were subdivided into a small decentration group (group S) and a large decentration group (group L) based on the median value of the weighted average decentration (dave ). Central axial length (AL) and peripheral eye lengths (PELs) at the central retina, as well as 10°, 20° and 30° nasally and temporally were measured at 0 and 13 months under cycloplegia. Second-order polynomial (y = ax2 + bx + c) and linear fits (y = Kx + B) were applied to the peripheral relative eye length (PREL), and the coefficients 'a' and 'K' were used to describe the shape of the eye. RESULTS: Mean AL growth for one year was 0.28 ± 0.17 mm. In a multiple linear regression model, AL elongation was related to the baseline age (ß = -0.41, p = 0.01) and the dave (ß = -0.37, p = 0.03) (R2  = 0.34, p = 0.002). When compared with smaller dave (0.45 ± 0.15 mm), a larger dave (0.89 ± 0.17 mm) was associated with slower ocular growth (central: 0.20 ± 0.13 mm vs. 0.35 ± 0.17 mm, p = 0.009; 10° nasal: 0.26 ± 0.18 mm vs. 0.45 ± 0.21 mm, p = 0.02; 10° temporal: 0.17 ± 0.14 mm vs. 0.32 ± 0.19 mm, p = 0.02) and more oblate retina shape ('a': -0.13 ± 0.02 vs. -0.14 ± 0.02, p = 0.02; Knasal : 0.35 ± 0.11 vs. 0.39 ± 0.09, p = 0.02; Ktemporal : -0.42 ± 0.08 vs. -0.46 ± 0.08, p = 0.004). CONCLUSIONS: Greater TZ decentration with the use of OK lenses was associated with slower axial growth and a more oblate retinal shape. TZ decentration caused local defocusing changes, which may inhibit myopic progression. These findings may have important implications for improving optical designs for myopia control.

Impact of Decentration and Tilt on Spherical, Aberration Correcting, and Specific Aspherical Intraocular Lenses: An Optical Bench Analysis.

INTRODUCTION: The human eye is not optically symmetrical, and very few intraocular lens (IOLs) are perfectly centered in the eye. That is why contrast sensitivity can degrade in some conditions, especially in low light. In an optical bench analysis, we compare spherical (A), aberration correcting (B), and specific aspherical lenses (C) in terms of impact of decentration and tilt on the modulation transfer function as well as the simulated overall quality with USAF test targets. MATERIAL AND METHODS: The OptiSpheric IOL PRO2 was used to measure the optical performance of IOLs (A, B, C). In order to assess the optical quality of the IOLs, the optical quality parameters for the aperture size of 3.0 mm and 4.5 mm at the IOL plane were assessed. Through Frequency Modulation Transfer Function (MTF) and Strehl Ratio (SR) values, as well as the "US Airforce 1951 resolution test chart images" as qualitative simulation, were analyzed. All measurements (ISO) were repeated and done for centered, decentered (1 mm), and tilted (5°) IOLs. RESULTS: Centered: The MTF (mean) at 50 lp/mm (IOL A, B, C) with 3.0-mm aperture was 0.794/0.716/0.797 (ISO-1 cornea) and 0.673/0.752/0.723 (ISO-2 cornea) and with 4.5-mm aperture 0.728/0.365/0.751 (ISO 1) and 0.276/0.767/0.505 (ISO 2). The SR (mean) with 3.0-mm aperture was 0.763/0.829/0.898 and with 4.5-mm aperture 0.228/0.386/0.432. Decentered by 1 mm: The MTF (mean) at 50 lp/mm with 3.0-mm aperture was 0.779/0.459/0.726 (ISO 1) and 0.695/0.381/0.662 (ISO 2). The MTF (mean) at 50 lp/mm with 4.5-mm aperture was 0.732/0.348/0.653 (ISO 1) and 0.355/0.069/0.346 (ISO 2). The SR (mean) with 3.0-mm aperture was 0.829/0.543/0.397 and with 4.5-mm aperture was 0.259/0.145/0.192. Tilted by 5°: The MTF (mean) at 50 lp/mm with 3.0-mm aperture was 0.731/0.705/0.751 (ISO 1) and 0.623/0.727/0.732 (ISO 2). The MTF (mean) at 50 lp/mm with 4.5-mm aperture was 0.579/0.406/0.701 (ISO 1) and 0.277/0.512/0.429 (ISO 2). The SR (mean) with 3.0-mm aperture was 0.539/0.478/0.514 and with 4.5-mm aperture was 0.262/0.136/0.201. CONCLUSION: Aberration correcting IOLs perform best when perfectly centered. The optical performance of aberration correcting IOLs can be markedly downgraded by misalignment. The examined ZO optic performed well in decentration and tilt. The ZO concept seems to be a good alternative to aspheric lenses, as it achieves to combine benefits of spherical and aspheric intraocular lenses. There is no perfect IOL, but fitting and choosing the right one for the individual case seems to be crucial to take advantage of benefits and minimize disadvantages. This is why knowledge of optical properties is also mandatory for the surgeon.