Capsule measuring ring to predict capsular bag diameter and follow its course after foldable intraocular lens implantation

A New Small-Aperture Device Implanted on Top of the Intraocular Lens: Safety, Feasibility, and First Clinical Results

PURPOSE

To investigate the feasibility and safety of a new small-aperture device, which is implanted on top of the intraocular lens.

METHODS

Regular cataract surgery was performed in both eyes in 7 patients. In the non-dominant eye, a small-aperture device (VisionXtender; Morcher) was additionally implanted into the capsular bag at the end of the surgery. The mask had an inner diameter of 1.4 mm. Feasibility and safety were investigated 3 months and 2 years after surgery.

RESULTS

In all cases, the device was successfully positioned in the capsular bag without any intraoperative complications. No inflammation was observed at the 3-month follow-up visit. All patients achieved binocular uncorrected distance visual acuity of 0 logarithm of the minimum angle of resolution (log-MAR) or better. Additionally, distance-corrected intermediate visual acuity of 0.1 logMAR or better was measured in the non-dominant eye. Two years postoperatively, Nd:YAG capsulotomy was performed in three patients in both eyes.

CONCLUSIONS

This clinical feasibility trial demonstrates that the use of the new small-aperture device is both easy and safe. No intraoperative or postoperative complications were reported. All patients attained satisfactory distance, intermediate, and near visual acuity. The device shows significant potential when used in combination with different intraocular lenses (eg, toric). In the future, different opening shapes seem to be possible. [J Refract Surg. 2024;40(9):e662-e666.].

Hydrophobic Trifocal Toric Intraocular Lens Outcomes in Japanese Eyes After Cataract Surgery

Purpose

To analyze the refractive and visual outcomes following cataract surgery and implantation of a new hydrophobic trifocal toric intraocular lens (IOL) in Japanese eyes with different degrees of corneal astigmatism.

Methods

A total of 66 eyes from 39 patients implanted with a FineVision HP Toric IOL (Beaver-Visitec International Inc) were analyzed retrospectively. The main outcome measures considered were refraction, monocular uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), uncorrected intermediate visual acuity (UIVA), and distance-corrected intermediate visual acuity (DCIVA) at 80 and 66 cm, uncorrected near visual acuity (UNVA) and distance-corrected near visual acuity (DCNVA) at 40 cm. Eyes were evaluated at three months post-surgery.

Results

Sixty-five eyes (98.48%) were within ±0.50D of spherical equivalent, and all were within ±1.00D (mean: 0.00±0.21D). Moreover, 63 eyes (95.45%) had ≤0.50D of residual astigmatism, and all had ≤1.00D (mean: -0.08±0.23D). Similarly, 58 (87.88%) and 60 eyes (90.91%) had ≥20/20 UDVA and CDVA, respectively, with 65 (98.48%) and 66 eyes (100%) achieving ≥20/25 UDVA and CDVA, respectively. In addition, 28 (42.42%) and 23 eyes (34.85%) had ≥20/25 DCIVA at 80 and 66 cm, respectively, with 49 (74.24%) and 52 eyes (78.79%) achieving ≥20/32 DCIVA at 80 and 66 cm, respectively. Finally, 39 (59.09%) and 40 eyes (60.61%) had ≥20/20 UNVA and DCNVA, respectively, with 58 (87.88%) and 59 eyes (89.39%) achieving ≥20/25 UNVA and DCNVA, respectively.

Conclusion

Our study shows that implantation of the new hydrophobic FineVision HP Toric IOL results in accurate refractive outcomes, with good visual acuity at different distances, in Japanese eyes.

Influence of Ocular Biometric Parameters on Intraocular Lens Position: A Prospective Cohort Study

PURPOSE

To assess the influence of ocular biometric parameters on intraocular lens (IOL) tilt and decentration after cataract surgery.

METHODS

Patients scheduled for cataract surgery were screened for inclusion in this prospective cohort study. Tilt and decentration of the crystalline lens and IOL were measured using the CASIA2 (Tomey). Anterior chamber depth (ACD), lens thickness (LT), and axial length (AL) were preoperatively measured by the IOLMaster 700 (Carl Zeiss Meditec AG). Multivariate regression analysis was performed to assess the influence of ocular biometric parameters on IOL tilt and decentration after cataract surgery.

RESULTS

In total, 191 eyes of 120 patients were included. Age was positively correlated with IOL tilt, whereas ACD and AL were negatively correlated with IOL tilt. A strong positive correlation was found between preoperative crystalline lenses and postoperative IOLs in tilt magnitude (r = 0.769, P < .001) and tilt direction (r = 0.688, P < .001). A positive correlation was found between preoperative and postoperative lens decentration magnitude and decentration direction. Greater postoperative IOL tilt and decentration were significantly associated with greater preoperative crystalline lens tilt (P < .001) and decentration (P = .027).

CONCLUSIONS

IOL tilt was greater in older patients. Shorter AL and shallower ACD contributed to greater IOL tilt. The tilt and decentration of the IOL will be greater in patients with greater tilt and decentration of the crystalline lens. [J Refract Surg. 2024;40(7):e438-e444.].

Exploring anterion capsular contraction syndrome in cataract surgery: insights into pathogenesis, clinical course, influencing factors, and intervention approaches

Anterior capsular contraction syndrome (ACCS) is a challenging complication that can occur following phacoemulsification cataract surgery. Characterized by capsular bag wrinkling, intraocular lens (IOL) decentration and tilt, ACCS can have negative effects on visual outcomes and patient satisfaction. This review aims to investigate the pathogenesis, clinical course, influencing factors, and intervention approaches for ACCS after cataract surgery. By understanding the underlying mechanisms and identifying factors that contribute to ACCS, surgeons can enhance their ability to predict and manage this complication. Various intervention strategies are discussed, highlighting their importance in reducing complications and improving surgical outcomes. However, further research is needed to determine optimal prevention and management strategies through long-term follow-up and comparative analyses. Advancements in this field will ultimately lead to improved visual outcomes and optimized cataract surgery for patients.

Implantation of a capsular tension ring during cataract surgery attenuates predicted remodeling of the post-surgical lens capsule along the visual axis

Introduction: Cataract surgery permanently alters the mechanical environment of the lens capsule by placing a hole in the anterior portion and implanting an intraocular lens (IOL) that has a very different geometry from the native lens. We hypothesized that implant configuration and mechanical interactions with the post-surgical lens capsule play a key role in determining long-term fibrotic remodeling. Methods: We developed the first finite element-growth and remodeling (FE-G&R) model of the post-surgical lens capsule to evaluate how implantation of an IOL with and without a capsular tension ring (CTR) impacted evolving lens capsule mechanics and associated fibrosis over time after cataract surgery. Results: Our models predicted that implantation of a CTR with the IOL into the post-surgical lens capsule reduced the mechanical perturbation, thickening, and stiffening along the visual axis in both the remnant anterior and posterior portions compared to implantation of the IOL alone. Discussion: These findings align with patient studies and suggest that implantation of a CTR with the IOL during routine cataract surgery would attenuate the incidence of visually-debilitating capsule fibrosis. Our work demonstrates that use of such modeling techniques has substantial potential to aid in the design of better surgical strategies and implants.

Long-term trifocal toric intraocular lens outcomes in Asian eyes after cataract surgery

PURPOSE

To determine the visual and refractive outcomes of trifocal toric intraocular lens (IOL) implantation in Asian eyes with cataract and astigmatism.

SETTING

Asian Eye Institute, Makati City, Philippines.

DESIGN

Prospective study.

METHODS

187 eyes were implanted with the FineVision POD FT IOL and followed for 2 years. The measurements included subjective refraction, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), uncorrected intermediate visual acuity (UIVA), distance-corrected intermediate visual acuity (DCIVA), uncorrected near visual acuity (UNVA), distance-corrected near visual acuity (DCNVA), defocus curve, photopic and mesopic contrast sensitivity, and rotational stability.

RESULTS

The mean spherical equivalent and cylinder values were, respectively, -0.07 ± 0.34 diopters (D) and -0.48 ± 0.31 D at the 2-year follow-up. At this same follow-up, 69.4% of patients had monocular CDVA and 79.3% had binocular UDVA ≤0.0 logMAR. For intermediate vision, monocular DCIVA reached 74.1%, while binocular UIVA was 86.2% ≤ 0.1 logMAR. Near vision showed 63% for monocular DCNVA and 70.7% for binocular UNVA ≤0.1 logMAR. The mean values at this follow-up were 0.02 ± 0.08, 0.08 ± 0.10, and 0.10 ± 0.12 logMAR for CDVA, DCIVA, and DCNVA, respectively. At the visual acuity threshold of ≤0.20 logMAR, the binocular defocus curve extended up to -3.75 D. Stable contrast sensitivity values were obtained at the different follow-ups. The mean IOL rotation was ≤2 degrees.

CONCLUSIONS

The FineVision POD FT IOL yielded good visual outcomes at far, near, and intermediate distances with accurate refractive outcomes and good rotational stability in Asian eyes.

Conforming to the anatomy and not the standard: A technique of eccentric capsulorrhexis and intraocular lens haptic amputation for eyes with iris coloboma

PURPOSE

To describe a novel technique for cataract surgery in patients with iris coloboma.

METHODS

The technique involves 1) creation of an inferiorly displaced capsulorrhexis and 2) amputation of one intraocular lens (IOL) haptic, thus allowing for controlled IOL decentration in the direction of an inferior iris defect.

RESULTS

We report favorable outcomes in two eyes (one patient) where eccentric capsulorrhexis and haptic amputation were employed during one-piece IOL repositioning in one eye and cataract surgery with three-piece IOL implantation in the contralateral eye.

CONCLUSION

In coloboma patients who are asymptomatic from their iris defect and do not have a cosmetic desire for repair, eccentric capsulorrhexis and IOL haptic amputation is a viable surgical option that allows for the preservation of a clear visual axis without the need for iris repair.

Long Term Clinical Outcomes of Hydrophilic and Hydrophobic Versions of a Trifocal IOL with the Same Optical Design

Purpose

To show the visual and refractive outcomes in Asian eyes with cataract when bilaterally implanted with either a hydrophobic FineVision POD F GF or a hydrophilic FineVision POD F intraocular lens (IOL).

Methods

Forty-six patients were randomized to receive POD F GF or POD F IOLs. Visual and refractive outcomes were assessed up to 24 months post-surgery. Measurements included uncorrected-distance visual acuity, corrected-distance visual acuity (CDVA), distance-corrected intermediate visual acuity (DCIVA), distance-corrected near visual acuity (DCNVA), refraction, defocus curve, photopic and mesopic contrast sensitivity, and patient-reported outcomes.

Results

Mean spherical equivalent was close to emmetropia for both groups and stable across postoperative visits. Overall, 97.73% and 100% of eyes in the POD F GF IOL group and 95.65% and 100%, of eyes in the POD F IOL group were within ±1.00D of the target refraction at 12 and 24 months, respectively. All patients showed a CDVA of ≥20/25 at 12- and 24-months post-surgery. In both groups, 24 months post-surgery 91% of patients presented a DCIVA of ≥20/25 and 83.3% of patients had a DCNVA of ≥20/25. Defocus curve showed continuous visual acuity, being 20/32 or better in both groups over a 4.00D range between 1.00D and -3.00/-3.50D. Both groups showed good contrast sensitivity values for photopic and mesopic conditions. Overall, 86.4%, 86.4%, and 72.7% of patients implanted with the POD F GF IOL reported not wearing glasses at all for distance, intermediate, and near vision, respectively. These values were 81.8%, 86.4%, and 90.9% for patients implanted with the POD F IOL. Both groups of patients reported similar satisfaction percentages (100% very satisfied/satisfied) and would recommend the procedure (100% definitively yes/probably yes).

Conclusion

This study demonstrates good visual and refractive outcomes for both the FineVision POD F GF and the FineVision POD F IOLs when implanted in Asian eyes.

Effect of capsular bend on the rotational stability of toric intraocular lens

PURPOSE

To assess the effect of capsular bend and axial length on the rotational stability of toric IOL.

METHODS

The prospective study included patients with preexisting astigmatism that were implanted with Acrysof IQ Toric IOL. According to the pre‑operative axial length, all patients were divided into 2 groups: high myopia (AL ≥ 26 mm) group, and emmetropia or low to moderate myopia group (AL <26 mm). High-speed Swept-source Optical Coherence Tomography (SS-OCT) radial scanning was performed after pupil dilation to obtain the toric IOL axial orientation and capsular bending index (CBI) at 1-day, 1-week, 1-month and 3-month intervals postoperatively. The correlation between the rotation of toric intraocular lens and the axial length or CBI was subsequently analyzed.

RESULTS

68 eyes of 57 patients were included in the research. The rotation of toric IOL within the high myopia group was greater than the control group (P = 0.001, 1month postoperative). Capsular contact with the IOL was delayed in highly myopic eyes, although the results were not statistically significant (P = 0.094, 1-month postoperatively). There was a positive correlation between the degree of rotation and axial length at the interval found between 1-week and 1-month after the operation (r = 0.333, P = 0.005). There was a significant negative correlation between the IOL rotational speed and CBI (P < 0.001). The regression equation was Y = -0.441*X + 1.712 (R2 = 0.323, P < 0.001).

CONCLUSION

There was a significant negative correlation between the IOL rotation speed and the CBI, while the influence of the axial length and capsular bending mainly occurred between one week and one month after the operation.

An Experimental Laboratory Study Using the Miyake-Apple Posterior View Technique to Investigate the Dynamics Between Capsular Bags and Different IOL Models

PURPOSE

To evaluate the dynamics between capsular bags and different intraocular lens (IOL) models in human cadaver eyes using the Miyake-Apple posterior view technique.

METHODS

In an in vitro laboratory study, human cadaver eyes were prepared according to the Miyake-Apple posterior view technique. Five IOLs from each of the six groups (Avansee 1P [Simonvision], Avansee 3P [Simonvision], CT Lucia [Carl Zeiss Meditec], Acrysof [Alcon Laboratories, Inc], RayOne [Rayner], and CT Asphina [Carl Zeiss Meditec]) were implanted into capsular bags with different diameters. The empty capsular bag diameter and capsular bag diameter with an IOL in it were evaluated based on the Miyake-Apple view pictures. Posterior capsule striae were observed and compared between groups. The arc of contact between IOLs and the capsular equator was noted. Correlations between the empty capsular bag diameter and the capsular bag diameter with IOL, as well as between the empty capsular bag diameter and the arc of contact, were examined. With the Avansee 3P as a reference, the area deviation of the haptics of IOL models with looped haptics was compared.

RESULTS

The capsular bag diameter with IOL inside and the arc of contact were proportional to the empty capsular bag diameter. The RayOne, Avansee 3P, and CT Lucia showed a longer arc of contact. Posterior capsule striae were observed in the Avansee 1P (1, 20%), Avansee 3P (5, 100%), Acrysof (1, 20%), and RayOne (2, 40%). Areas of deviation were 0.38 mm² (Avansee 1P), 0.24 mm² (CT Lucia), 0.34 mm² (Acrysof), and 0.31 mm² (RayOne), respectively.

CONCLUSIONS

Different IOL models showed varied characteristics in terms of capsular bag fitting and arc of contact. Understanding these dynamics is critical to optimizing postoperative outcomes. [J Refract Surg. 2022;38(10):654-660.].

Clinically Significant Intraocular Lens Decentration and Tilt in Highly Myopic Eyes: A Swept-Source Optical Coherence Tomography Study

PURPOSE

To investigate the occurrence and risk factors of clinically significant intraocular lens (IOL) decentration and tilt in highly myopic eyes using swept-source anterior segment optical coherence tomography (SS-AS-OCT).

DESIGN

Cross-sectional study.

METHODS

This study included 334 participants (334 eyes) with high myopia, defined as axial length (AL) ≥26 mm, who underwent phacoemulsification with IOL implantation. Decentration and tilt of IOL were assessed by SS-AS-OCT. Clinically significant IOL decentration and tilt was defined as decentration ≥0.4 mm and tilt ≥7°. Routine preoperative and postoperative examinations included visual acuity, refraction, biometric measurement using IOLMaster 700 (Carl Zeiss Meditec), and objective visual quality evaluated by OPD-Scan III (Nidek Technologies).

RESULTS

Among the 334 highly myopic participants, 71 (21.3%) had clinically significant IOL decentration, and 26 (7.78%) had clinically significant IOL tilt. The proportion of clinically significant IOL decentration (37.1% vs 14.0%, P < .001) and tilt (16.2% vs 3.90%, P < .001) in those with AL ≥30 mm was significantly higher than in those with AL <30 mm. The multivariable logistic regression model showed only AL ≥30 mm was associated with clinically significant IOL decentration (odds ratio, 1.65; P = .002). AL ≥30 mm (odds ratio, 2.09; P = .001) was an independent risk factor for clinically significant IOL tilt after adjusting for confounders. AL ≥30.3 mm could effectively predict IOL decentration ≥0.6 mm (area under the curve, 0.802).

CONCLUSIONS

Participants with AL >30 mm have a higher risk of clinically significant IOL decentration and tilt, thus caution should be taken to implant multifocal or toric IOL for these patients.

Associations between anterior segment parameters and rotational stability of a plate-haptic toric intraocular lens

PURPOSE

To evaluate the associations between anterior segment parameters and the rotational stability of a plate-haptic toric intraocular lens (IOL).

SETTING

Eye and Ear, Nose, Throat Hospital of Fudan University.

DESIGN

Retrospective case series.

METHODS

Patients who underwent uneventful phacoemulsification and plate-haptic toric IOL (AT TORBI 709M IOL) implantation were included. Preoperative axial length (AL) and anterior segment parameters, including the white-to-white (WTW) distance, anterior chamber depth (ACD), lens thickness (LT), and anterior segment length (ASL; the sum of ACD and LT) were recorded. IOL rotation, residual astigmatism (RAS), and visual acuity were evaluated 1 month postoperatively. The associations between the anterior segment parameters and IOL rotation were evaluated.

RESULTS

A total of 102 eyes of 102 patients were included. The mean AL was 26.43 ± 2.65 mm (range 21.71-34.60 mm). The mean IOL rotation was 4.59 ± 3.18 degrees, and RAS was 0.62 ± 0.39 D postoperatively. No correlation was detected between AL, ACD, or LT and the rotation of the plate-haptic toric IOL (all P > .05). However, its rotation correlated positively with the WTW distance (r = 0.250, P = .011) and ASL (r = 0.214, P = .030). Backward stepwise multiple linear regression revealed that the WTW distance (β = 2.142, P = .014) and ASL (β = 2.060, P = .037) were independent predictors of plate-haptic toric IOL rotation.

CONCLUSIONS

Plate-haptic toric IOLs rotate more in eyes with larger WTW distances and longer ASLs; therefore, toric IOL implantation should be performed with caution in eyes with these characteristics.

Long-Term Clinically Significant Posterior Capsular Opacification Development Pattern in Eyes Implanted with an Aspheric Monofocal Intraocular Lens with a Square Optic Edge

Purpose

To analyse the posterior capsular opacification (PCO) development pattern in the long term in eyes implanted with a monofocal intraocular lens (IOL) with a square edge all around the optic.

Methods

Longitudinal retrospective study is data analyzed from a total of 7059 eyes from 4764 patients (mean age: 75.8 years) undergoing cataract surgery with implantation of an aspheric monofocal IOL (Bi-Flex HL 677AB/677P, Medicontur, Budapest, Hungary). These data were retrospectively collected using the electronic medical record of the hospitals involved. Nd : YAG capsulotomy rates were calculated per year during a follow-up of more than 10 years. The Kaplan–Meier analysis was used to establish the transparent capsule survival rate.

Results

The Nd : YAG capsulotomy rate increased from 1.1% at 1 year postoperatively to 17.2% at 5 years after surgery. No significant differences were found between eyes with and without capsulotomy in terms of age (p = 0.202), gender (p = 0.061), type of anaesthesia used (p = 0.128), and presence of conditions such as hard cataract (p = 0.111) or pseudoexfoliation (p = 0.137). IOL power was significantly lower in those eyes of patients requiring Nd : YAG capsulotomy during the follow-up (p < 0.001). Significantly more eyes implanted with the preloaded model of the IOL required capsulotomy (p < 0.001). Mean survival time and rate were 9.38 years and 85.9%, respectively.

Conclusions

Most eyes undergoing cataract with implantation of the Bi-Flex IOL do not develop a clinically significant PCO requiring Nd : YAG capsulotomy in the long term. IOL material and design may be the main factors accounting for this finding.

Comparison of the Stability of Two Intraocular Lenses in Primary Angle-Closure Glaucoma after Phacoemulsification

Objective. To observe the stability of intraocular lenses (IOLs) in primary angle-closure glaucoma by ultralong scan depth spectral-domain optical coherence tomography (UL-OCT) after phacoemulsification. Methods. A prospective, randomized study. 73 patients (82 eyes) with primary closed-angle glaucoma and age-related cataract were included in the study. 42 eyes were implanted with ZCB00, while 40 eyes were implanted with Softec HD after phacoemulsification. The tilt, decentration, and space between IOL and posterior capsule (IOL-PC space) were analyzed using UL-OCT at 1 week, 1 month, and 3 months after surgery. The intergroup difference was compared with the paired t-test. Result. The difference of decentration and tilt was not statistically significant (both $P>0.05$ ) both in the horizontal and vertical positions at 1 week, 1 month, and 3 months postoperatively. The horizontal IOL-PC space is 0.111 ± 0.091 mm2, 0.044 ± 0.066 mm2, and 0.055 ± 0.055 mm2 in the Softec HD group and 0.458 ± 0.488 mm2, 0.497 ± 0.363 mm2, and 0.492 ± 0.441 mm2 in the ZCB00 group. The vertical IOL-PC space is 0.102 ± 0.061 mm2, 0.037 ± 0.052 mm2, and 0.053 ± 0.079 mm2 in the Softec HD group and 0.692 ± 0.815 mm2, 0.510 ± 0.415 mm2, and 0.691 ± 0.635 mm2 in the ZCB00 group. The difference was statistically significant ( $P<0.05$ ) both in the horizontal and vertical positions except for the first week on the horizon. The Softec HD group is smaller than the ZCB00 group. Conclusion. There is no difference in the stability of the IOL although the IOL-PC space is different. The thickness of IOL may affect the IOL-PC space.

Altered stress field of the human lens capsule after cataract surgery

The lens capsule of the eye is important in focusing light onto the retina during the process of accommodation and, in later life, housing a prosthetic lens implanted during cataract surgery. Though considerable modeling work has characterized the mechanics of accommodation, little has been done to understand the mechanics of the lens capsule after cataract surgery. As such, we present the first 3-D finite element model of the post-surgical human lens capsule with an implanted tension ring and, separately, an intraocular lens to characterize the altered stress field compared to that in a model of the native lens capsule. All finite element models employed a Holzapfel hyperelastic constitutive model with regional variations in anisotropy. The post-surgical lens capsule demonstrated a dramatic perturbation to the stress field with mostly large reductions in stresses (except at the equator where the implant contacts the capsule) compared to native, wherein maximal changes in Cauchy stress were -100% and -145% for the tension ring and intraocular lens, respectively. However, implantation of the tension ring produced a more uniform stress field compared to the IOL. The magnitudes and distribution of the perturbed stress field may be an important driver of the fibrotic response of inhabiting lens epithelial cells and associated lens capsule remodeling after cataract surgery. Thus, the mechanical effects of an implant on the lens capsule could be an essential consideration in the design of intraocular lenses, particularly those with an accommodative feature.

Evaluation of Lens Capsule Stability Using Capsular Tension Ring, Iris Retractor, and Capsule Expander Using a Porcine Model With Zonular Dehiscence

Purpose

We evaluate the efficacy of capsular tension rings (CTRs), iris retractors (IRs), and capsule expanders (CEs) in stabilizing the lens capsule under different degrees of zonular dehiscence using a porcine model.

Methods

We developed an experimental model that can be used to observe the dynamics of lens capsules with different degrees of zonular dehiscence during phacoemulsification and aspiration (PEA). PEA was performed without any aid (control) and with devices. A CTR was used for a dehiscence of 30°, 45°, 60°, 90°, 120°, 150°, and 180° and one to four IRs or one to three CEs were used for a dehiscence of 90°, 120°, and 180°. The retention rate, calculated as the area of the capsular bag during PEA divided by the area before zonular dissection, and the number of lens fragments dropped into the vitreous cavity during PEA were examined and compared among the control and experimental groups.

Results

The retention rate increased significantly with the use of devices compared to the control (P < 0.05). The number of dropped lens fragments decreased by one or less with the use of CTR, one IR, or one CE for 90°, two IRs, or one or two CEs for 120°, and three or four IRs, or two or three CEs for 180° of zonular dehiscence.

Conclusions

The experimental porcine eye model with zonular dehiscence makes it possible to observe the entire configuration of the lens capsule, and demonstrates differences in the efficacy of capsular bag retention with CTR, IR, and CE.

Efficacy of 4-Haptic Bitoric Intraocular Lens Implantation in Asian Patients with Cataract and Astigmatism

PURPOSE

To determine the efficacy of 4-haptic bitoric intraocular lens (IOL) implantation in Asian patients with cataract and astigmatism.

METHODS

A total of 19 eyes with ≤25.0 mm axial length and ≥0.75 diopters (D) corneal astigmatism were included in this prospective non-comparative study. All subjects underwent phacoemulsification with implantation of an AT Torbi 709M IOL. Visual and refractive outcomes as well as toric IOL axis were evaluated during a 3-month follow-up. Errors in predicted residual spherical equivalent were calculated by subtracting predicted residual spherical equivalent from postoperative refraction.

RESULTS

Uncorrected and corrected distance visual acuity improved significantly 3 months after surgery, from 0.43 to 0.05 and from 0.24 to -0.05, respectively. Mean refractive cylinders also decreased significantly, from -1.91 preoperatively to -0.54 D 3 months after surgery. Mean J0 and J45 decreased 3 months postoperatively, from 0.26 to 0.03 D and from 0.24 to -0.06 D, respectively. After 3 months, mean absolute IOL rotation was 1.81°. Errors in predicted residual spherical equivalent showed a hyperopic shift of 0.35 D.

CONCLUSIONS

Implantation of 4-haptic bitoric IOL proved to be effective for correcting astigmatism in Asian eyes during cataract surgery.

Evaluation of intraocular lens position during phacoemulsification using intraoperative spectral-domain optical coherence tomography

PURPOSE

To assess the position of intraocular lenses (IOLs) at the end of standard phacoemulsification with intraoperative spectral-domain optical coherence tomography (SD-OCT).

SETTINGS

Department of Ophthalmology, Rudolf Foundation Hospital, Vienna, Austria.

DESIGN

Prospective case series.

METHODS

Standard phacoemulsification with IOL implantation was performed. The Rescan 700 SD-OCT system was used for intraoperative imaging. The anterior segment of the eye was scanned using SD-OCT at the end of the surgery. The distance from the IOL optic center and the IOL optic edge to the posterior capsule was measured postoperatively using graphic software.

RESULTS

The study comprised 74 patients (101 eyes). The mean axial length was 23.97 mm (range 21.43 to 28.61 mm). The mean IOL power was 20.39 diopters (D) (range 6.5 to 27.5 D). Contact between the IOL and posterior capsule was absent in 88 cases (87.13%), and partial or full contact was present in 13 cases (12.87%). The mean distance between the IOL central optic and posterior capsule was 0.71 pixel (range 0.06 to 1.38 pixels) in 99 cases (98.02%). In 42 cases (57.53%), partial contact between the IOL edges and the posterior capsule was noticed. The mean distance between the IOL edge and posterior capsule was 0.21 pixel (range 0.04 to 0.92 pixel).

CONCLUSIONS

Intraoperative SD-OCT facilitated the imaging of IOL position during standard phacoemulsification. Contact between the IOL central optic and posterior capsule at the end of the surgery occurred rarely. Improved IOL design should be considered.

FINANCIAL DISCLOSURE

Drs. Binder and Glittenberg are consultants to Carl Zeiss Meditech AG. None of the other authors has a financial or proprietary interest in any material or method mentioned.

In vivo evaluation of a new hydrophobic acrylic intraocular lens in the rabbit model

PURPOSE

To evaluate the uveal and capsular biocompatibility as well as positioning stability of a new hydrophobic acrylic intraocular lens (IOL) in vivo in the rabbit model and compare it with a commercially available IOL.

SETTING

John A Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.

DESIGN

Experimental study.

METHODS

Fifteen New Zealand rabbits had the new test IOL (Clareon CNA0T0) implanted in one eye and a control IOL (Acrysof SN60WF) implanted in the contralateral eye. The test IOL is manufactured from a new hydrophobic acrylic material incorporating ultraviolet blocker and blue light filter. Its design is based on the control IOL's platform. The rabbits were followed up with weekly slitlamp evaluations, which assessed inflammatory reactions as well as capsular bag opacification. Anterior chamber depth was measured at 1 and 4 weeks post-implantation (high-frequency ultrasound). After 4 weeks, the rabbits were killed humanely and the eyes were enucleated. The anterior segment was evaluated from the posterior or Miyake-Apple view, and was then processed for complete histopathology.

RESULTS

There were no statistically significant differences between test and control eyes in terms of postoperative inflammation and capsular biocompatibility, including posterior capsule opacification (P = .34, paired t test), and anterior capsule opacification (P = .53, paired t test), as observed during clinical and pathological evaluation. In vivo axial positioning for the test IOL was comparable to the control IOL and stable over time (P = .531 versus P = .788).

CONCLUSIONS

The new IOL showed biocompatibility and stability comparable to the control IOL.

Influence of total intraocular lens diameter on efficacy and safety for in the bag cataract surgery

CONTEXT

Intraocular lenses with variable total diameter are supposed to fit better in the capsular bag and lead to fewer complications.

AIMS

This study aims to investigate the efficacy and the safety of an intraocular lens model with variable total diameter.

SETTINGS AND DESIGN

Prospective randomized intraindividual study.

SUBJECTS AND METHODS

Thirty-two eyes of sixteen patients with bilateral age-related cataract received standard cataract surgery with implantation of an intraocular lens with a standard diameter in one eye (Quatrix®, Group A) and with a variable total diameter in the fellow eye (Quatrix Evolutive®, Group B). Primary study endpoints included evaluation of refraction stability and posterior capsule opacification (PCO) over a follow-up period of 6 months.

STATISTICAL ANALYSIS USED

SPSS (Version 19.0) was used for statistical analysis.

RESULTS

Uncorrected and corrected distant visual acuity after 6 months were 0.24 and 0.1 LogMAR in Group A and 0.23 and 0.09 LogMAR in Group B, respectively. The objective and manifest spherical equivalent (OSE, MSE) 6 months postoperatively were + 0.65 D and + 0.62 D in Group A compared to + 0.33 D and + 0.33 D in Group B respectively (P = 0.665 for OSE, P = 0.208 for MSE). PCO-index increased statistically significant in both groups (P = 0.004 in Group A, P = 0.046 in Group B), but the difference of PCO-index between both groups was not statistically significant (P = 0.569).

CONCLUSIONS

An intraocular lens with a variable total diameter shows good visual outcomes and safety performance as well as same outcomes concerning postoperative refractive stability and development of PCO compared to an intraocular lens with standard total diameter.

Posterior capsular opacification in highly myopic eyes with an endocapsular equator ring

PURPOSE

Closed 9.5-mm-diameter endocapsular equator rings (E-rings) prevent posterior capsular opacification (PCO). However, in our research, some highly myopic patients unexpectedly developed late, extensive PCO that required capsulotomy. We also report for the first time how the capsule reacted to neodymium-doped yttrium aluminium garnet (Nd:YAG) laser shots.

METHODS

Sixty-two eyes (39 patients; average age, 48 ± 13.2 years) were implanted with a closed, square-edged silicone E-ring (outer diameter, 9.5 mm) and an intraocular lens between April 16, 2008, and November 30, 2011.

RESULTS

During the postoperative, minimal 2-year follow-up, PCO requiring Nd:YAG laser capsulotomy developed in six (9.7 %) of 62 eyes, of which five had -8.75 to -12.5 diopters (D) of myopia preoperatively. The axial lengths of those eyes ranged from 25.86 to 29.97 mm. However, none of the 13 eyes with higher myopia had severe PCO that required capsulotomy. All capsulotomies were performed uneventfully.

CONCLUSION

The standard 9.5-mm-diameter closed E-ring does not prevent extensive PCO in eyes with preoperative myopia ranging between -8.75 and -12.5 D and an axial length between 25.86 and 29.97 mm. Posterior capsulotomies were performed safely. Further study is needed to determine why PCO did not occur in more high myopic eyes (larger axial length eyes).

Pediatric cataract: challenges and future directions

Cataract is a significant cause of visual disability in the pediatric population worldwide and can significantly impact the neurobiological development of a child. Early diagnosis and prompt surgical intervention is critical to prevent irreversible amblyopia. Thorough ocular evaluation, including the onset, duration, and morphology of a cataract, is essential to determine the timing for surgical intervention. Detailed assessment of the general health of the child, preferably in conjunction with a pediatrician, is helpful to rule out any associated systemic condition. Although pediatric cataracts have a diverse etiology, with the majority being idiopathic, genetic counseling and molecular testing should be undertaken with the help of a genetic counselor and/or geneticist in cases of hereditary cataracts. Advancement in surgical techniques and methods of optical rehabilitation has substantially improved the functional and anatomic outcomes of pediatric cataract surgeries in recent years. However, the phenomenon of refractive growth and the process of emmetropization have continued to puzzle pediatric ophthalmologists and highlight the need for future prospective studies. Posterior capsule opacification and secondary glaucoma are still the major postoperative complications necessitating long-term surveillance in children undergoing cataract surgery early in life. Successful management of pediatric cataracts depends on individualized care and experienced teamwork. We reviewed the etiology, preoperative evaluation including biometry, choice of intraocular lens, surgical techniques, and recent developments in the field of childhood cataract.

A prospective randomized clinical evaluation of 3 presbyopia-correcting intraocular lenses after cataract extraction

PURPOSE

To compare contrast sensitivity, visual acuity (VA), and halos in subjects bilaterally implanted with 1 of 3 FDA-approved presbyopia-correcting intraocular lenses.

DESIGN

Prospective, randomized, partially masked, multicenter clinical trial.

METHODS

Seventy-eight subjects were randomized sequentially for bilateral implantation with the Crystalens AO (Bausch & Lomb Surgical), AcrySof IQ ReSTOR +3.0 (Alcon Laboratories), or Tecnis Multifocal (Abbott Medical Optics) lenses. Subjects were evaluated through visit 4 (4 to 6 months after surgery) with the following monocular and binocular assessments: high- and low-contrast VA, contrast sensitivity without glare, halos or starbursts, defocus curves, optical scatter, retinal point spread function, and safety.

RESULTS

The Crystalens AO and ReSTOR +3.0 demonstrated better monocular and binocular contrast sensitivity without glare at low to mid spatial frequencies compared with the Tecnis Multifocal lens. Binocular uncorrected distance VA was not significantly different between the 3 lenses. The Crystalens AO had significantly better binocular low-contrast distance-corrected VA than the ReSTOR +3.0 and better mean monocular low-contrast DCVA than the Tecnis Multifocal lens. The Crystalens AO demonstrated significantly better monocular and binocular uncorrected and distance-corrected intermediate VA than the ReSTOR +3.0 or Tecnis Multifocal lenses. The ReSTOR+3.0 lens had significantly better monocular and binocular uncorrected and distance-corrected near VA tested at 40 cm compared with the Crystalens AO and Tecnis Multifocal lens. The Crystalens AO elicited significantly less halos than the Tecnis Multifocal lens and less optical scatter than the ReSTOR +3.0 or Tecnis Multifocal lens.

CONCLUSIONS

The Crystalens AO had statistically better uncorrected intermediate VA and distance-corrected intermediate VA than the ReSTOR +3.0 or Tecnis Multifocal lenses and fewer photic phenomenon than the Tecnis Multifocal lens. Both multifocals had better distance-corrected near VA and uncorrected near VA than the Crystalens AO. These findings may guide intraocular lens selection for individual patients seeking to optimize vision at specific vergences or lighting conditions.

Capsular adhesion to intraocular lens in highly myopic eyes evaluated in vivo using ultralong-scan-depth optical coherence tomography

PURPOSE

To evaluate the in vivo capsular apposition to the intraocular lens (IOL) in subjects with high myopia by ultralong-scan-depth optical coherence tomography (OCT).

DESIGN

Prospective observational case series.

METHODS

Forty eyes from 40 cataract patients scheduled for phacoemulsification surgery at the Affiliated Eye Hospital, Wenzhou Medical College were studied, of which 20 eyes were highly myopic (axial length >26 mm) and 20 eyes were emmetropic (22 mm < axial length <24.5 mm). All eyes were examined with a custom-built ultralong-scan-depth OCT at 4 hours, 1 day, 7 days, 14 days, and 28 days after surgery.

RESULTS

Anterior capsule contact with the IOL was significantly delayed in highly myopic eyes. Complete apposition of the posterior capsule with the IOL was significantly less common among highly myopic eyes than in emmetropic eyes (4 vs 16 eyes; P = .001). Posterior capsule adhesion to the IOL was inversely correlated with axial length (r = -0.494, P < .001, nonparametric Spearman test). The 3 types of complete adhesive capsular bend configurations observed were classified as anterior adhesion, middle adhesion, and posterior adhesion. Incomplete adhesion patterns were classified as funnel adhesion, parallel adhesion, and furcate adhesion. Five highly myopic eyes had slight posterior capsule opacification (PCO) at the last follow-up, as did 1 emmetropic eye.

CONCLUSIONS

Ultralong-scan-depth OCT revealed weak capsular adhesion and incompletely adhesive types of capsular bend in highly myopic eyes. These features presumably increase the likelihood of PCO during the early postoperative period.

The influence of injection volume and capsular bag contraction on the refractive power of polymer refilled lenses - a finite element modelling simulation study

PURPOSE

Polymer injection into the capsular bag after phakoemulsification is an interesting and promising approach to lens surgery. Safe clinical application of this technique will require an appropriate estimate of the effect of implantation variables on the lens power. This article details the results of finite element investigations into the effects of the injected polymer volume and capsular bag contraction on the resultant lens power and accommodation amplitude.

METHODS

An axisymmetric finite element model was created from literature sources. Polymer injection and the capsular contraction were simulated, and their effect on the lens power was calculated.

RESULTS AND CONCLUSION

The simulations show that overfilling during polymer injection leads to a refractive power increase of the lens. Capsular bag contraction also results in a power increase. The calculated accommodative amplitude of the lens is minimally affected by capsular bag contraction but decreases significantly with increased capsular bag stiffness as a result of fibrosis.

Postoperative astigmatic outcomes based on the haptic axis of intraocular lenses inserted in cataract surgery

Purpose

This study was conducted to compare post-operative astigmatic outcomes of two groups, with-the-rule (WTR) and against-the-rule (ATR) astigmatism patients, according to the haptic axis of intraocular lenses (IOLs) inserted in cataract surgery.

Methods

Seventy-two eyes with WTR astigmatism and 79 eyes with ATR astigmatism had cataract surgery through a clear corneal temporal incision. These two groups of eyes were then each divided into 2 groups based on whether the haptic axis of the inserted IOL was at 180° or 90°. For ATR patients, the outcomes were analyzed according to the three types of IOLs.

Results

There was no difference in corneal astigmatism, but WTR patients with a 180° haptic axis of the inserted IOL and ATR patients with a 90° hepatic axis of the inserted IOL had a significant decrease in postoperative refractive astigmatism (p < 0.05). The changes in ATR astigmatism according to the IOL type were more effective in single-piece acrylic IOLs than in the three-piece polymethylmethacrylate haptic IOL group.

Conclusions

Insertion of the IOL at the 180° haptic axis in WTR patients and at 90° in ATR patients during cataract surgery may have an effect in reducing pre-existing astigmatism. This observed effect was not consistent among the different types of IOLs.

Computational model of evolving lens capsule biomechanics following cataract-like surgery

Cataract surgery is an invasive procedure whereby lens fibers are removed through a permanent central hole, or capsulorhexis, in the surrounding lens capsule and replaced with an artificial intraocular lens (IOL). Remnant lens epithelial cells subsequently transdifferentiate to a more contractile and synthetic wound-healing phenotype, which causes significant structural and mechanical adaptations of the residual lens capsule. The goal of this study is to present a computational model capable of capturing salient features of the biomechanical evolution of the lens capsule following cataract-like surgery. The model is shown to predict marked long-term increases in thickness and stiffness of the lens capsule nearest the edge of the capsulorhexis comparable to reported measurements. Such models represent a first step toward understanding better the long-term interactions between the residual lens capsule and implanted IOL, thus initiating a new paradigm for the design of improved IOLs, including those having an accommodative feature.

Ex vivo quantification of the time course of contractile loading of the porcine lens capsule after cataract-like surgery

Cataract surgery is an invasive procedure that replaces the quasi-spherical native lens fibers with a flat prosthetic device, which initially reduces mechanical stress within the remnant lens capsule and, ultimately, leads to contraction of the capsule about the implant. Although resultant changes in geometry have been quantified previously, little is known about the loads associated with this contraction. We present a novel experimental culture device to quantify ex vivo the time course of increases in tension within the contracting lens capsule after cataract-like surgery. Results demonstrate that contraction reaches steady state within approximately one month with a mean tension of 1.45 mN/mm and Cauchy (true) stress of 13.4 kPa. A significant increase in alpha-smooth muscle actin (alpha-SMA) was also found in post-cultured compared to fresh lens capsules, thus suggesting that transdifferentiated lens epithelial cells (LECs) modulated the contraction. Quantification of loads imparted by the contracting lens capsule is important for assessing implant/capsule interactions and implant stability in vivo. Because contraction of the capsule may be modulated in part by LECs attempting to restore their native mechanical environment, our results further suggest a possible mechanism for the long-term errant changes in capsular structure commonly observed after surgery.

Effect of a closed foldable equator ring on capsular bag shrinkage in cataract surgery

PURPOSE

To evaluate the effect of a closed foldable equator ring (CFER) versus a conventional capsular tension ring (CTR) on capsular bag shrinkage.

SETTING

Department of Ophthalmology, Johannes Gutenberg-University, Mainz, Germany.

METHODS

In this prospective study, 70 eyes of 70 patients were randomized to 2 groups using a 1:1 block scheme. After uneventful cataract surgery, a capsular measuring ring was implanted in all eyes to measure the capsular bag diameter in vivo. In Group 1, a CTR was implanted in the capsular bag. In Group 2, a CFER was inserted. Biometric characteristics such as axial length and the horizontal and vertical corneal radii were measured preoperatively. The capsular bag diameter and capsulorhexis diameter were measured intraoperatively and 2 or 3 days as well as 1 and 3 months postoperatively.

RESULTS

There were no statistically significant or clinically relevant between-group differences in covariants such as axial length, vertical and horizontal corneal radii, and capsulorhexis diameter. Eyes with the CTR had slight but statistically significant capsular bag shrinkage from a median of 10.4 to a median of 10.2 mm after 3 months (P<.001). Eyes with the CFER also had slight but statistically significant capsular bag shrinkage from a median of 10.3 to a median of 10.2 mm 3 months postoperatively (P = .021). At baseline, the CTR group had a larger capsular bag diameter, but there were no statistically significant differences between the groups at the 3-month follow-up (P = .669).

CONCLUSIONS

No clinically relevant capsular bag shrinkage was observed after implantation of a CFER or a CTR. The expected capsular bag shrinkage was the same in both groups.

Capsular bag shrinkage after implantation of a capsular bending or capsular tension ring

PURPOSE

To evaluate the influence of a capsular bending ring (CBR) or tension ring (CTR) on capsular bag shrinkage.

SETTING

Department of Ophthalmology, Johannes Gutenberg-University, and Department of Medical Biometry, Epidemiology and Informatics, University of Mainz, Mainz, Germany.

METHODS

In 92 eyes of 92 patients, a capsular measuring ring (CMR) was implanted after phacoemulsification to measure capsular bag size in vivo. Patients were randomized into 3 groups: The first received a CMR and CBR, the second received a CMR and CTR, and the third received a CMR alone. Measurements were performed preoperatively, intraoperatively, during the first 3 postoperative days, and after 1 and 3 months. Preoperative biometric characteristics such as axial length (AL) and anterior chamber depth were determined. Primary clinical end points were capsular bag size and capsulorhexis diameter measured intraoperatively and by means of slitlamp biomicroscopy and retroillumination photography postoperatively.

RESULTS

There were no clinically relevant group differences in AL, anterior chamber depth, or capsulorhexis diameter. Eyes implanted with the CBR showed shrinkage of the capsular bag from 10.6 to 10.4 mm after a median of 3 months (sign test; P = .023); eyes with a CTR showed comparable median capsular bag shrinkage from 10.5 to 10.2 mm (P<.001), whereas eyes without a CTR showed a median shrinkage from 10.5 to 10.0 mm (P<.001). Intraindividual shrinkage was of a similar, although significantly different, order among these groups (median shrinkage 0.15 versus 0.23 and 0.38 mm, respectively; all pairwise Wilcoxon test; P = .050, P = .020, P<.001, respectively).

CONCLUSIONS

Capsular shrinkage can be inhibited by a CBR and, to lesser extent, a CTR; the gain in shrinkage prevention is limited when compared with a CMR, however. This conclusion can be drawn only for the specific CBR or CTR and hydrophobic acrylic intraocular lens (IOL) used in this study. Reduction of capsular bag shrinkage after CTR implantation may reduce IOL dislocation and tilt and help to maintain postoperative visual acuity.

Accommodative intraocular lens tilting

PURPOSE

To report an unusual complication of accommodative intraocular lens (IOL) implantation after clear lens extraction for hyperopia correction.

DESIGN

Observational case report.

METHOD

A 48-year-old woman underwent clear lens exchange for the correction of moderate hyperopia. A Crystalens Model AT-45 Accommodating Posterior Chamber IOL (AT-45 IOL) was implanted to allow optimal distance and near vision. At the 3-week follow-up appointment, she complained of monocular diplopia. Ocular examination showed an increased astigmatism, causing decreased visual acuity. Scheimpflug Pentacam Image and Wave Front Analysis supported the diagnosis of IOL tilting.

RESULTS

IOL repositioning was unsuccessful because of fibrosis of the haptics. It was necessary to replace AT 45 IOL with a monofocal acrylic sulcus-fixated IOL.

CONCLUSION

Control of capsular fibrosis should be a major concern, especially in this type of IOL. Accommodating IOL exchange appears to be a safe alternative to manage this complication.

Effect of tilt of 2 acrylic intraocular lenses on high-order aberrations

PURPOSE

To investigate the high-order aberrations (HoAs) in pseudophakia between 2 foldable acrylic intraocular lenses (IOL) with differences in the tilt of IOL.

SETTING

Department of Ophthalmology, Nara Medical University, Nara, Japan.

METHOD

Sixty-four eyes that had uncomplicated phacoemulsification and IOL implantation were assigned to 1 of 2 groups: Acryfold 60BB (HOYA [n=30 eyes]) and AcrySof MA60AC (Alcon [n=34 eyes]). All patients had best corrected visual acuity better than 20/25. High-order aberrations were measured using the Hartmann-Shack aberrometer at 4.0 mm and 6.0 mm wavefront aperture diameters, and the IOL tilt and decentration were measured using Scheimpflug videophotography.

RESULTS

There was a significant difference in the IOL tilt (60BB=2.22 degrees +/- 1.44 (SD), 60AC=3.18 +/- 1.84 degrees; P=.041, Mann-Whitney U test), but no difference in IOL decentration (P>.05). In the cornea, there were no differences between the 2 groups in HoAs at 4.0 mm and 6.0 mm aperture diameters (P>.05, Mann-Whitney U test). In the whole eye, there was no difference between the 2 groups in spherical-like aberrations, coma-like aberrations, and total aberrations at the 4.0 mm and 6.0 mm aperture diameters (P>.05). The compensation of the internal optics with the 60BB group was better than with the 60AC group for coma-like (P=.037) and total aberrations (P=.010) at 6.0 mm aperture diameter.

CONCLUSION

The smaller tilt of the IOL induced more compensation for the coma-like and total aberrations at the 6.0 mm aperture diameter. The IOL tilt should be small, especially in a large pupil, with regard to HoAs.

Closed foldable capsular rings

A new foldable capsular tension and bending ring system with a sharp-edged design is described. The closed foldable capsular rings (CFCR) consist of 8 hydrophobic and 8 hydrophilic ring segments. The CFCRs have a 9.2 mm minimum overall diameter. The CFCRs were inserted using various cartridge systems or a two-folded technique with a forceps. The CFCRs were implanted after phacoemulsification through a small (1.6 to 3.2 mm) incision in 104 human adult eyes without intraoperative complications. No postoperative complications such as capsule folds or inward bending were observed over a 6-month follow-up. Posterior capsule opacification was minimal or absent in all eyes.

Accommodative intraocular lenses: current status

PURPOSE OF REVIEW

The possibility of using a monofocal IOL with accommodative ability allows refractive cataract surgery with a clearly decreased potential of photic phenomena. Three IOLs of different designs and materials have demonstrated accommodative ability, but the degree of accommodative amplitude has been reported to different extents and variabilities. The plate-haptic CrystaLens has a hinged design that might permit forward movement of the optic as a result of pressure changes in the vitreous cavity. The 1CU has modified haptics that bend in the bag as the lens capsule contracts, which are supposed to cause anterior displacement of the lens optic. With the dual-optic one-piece Synchrony, springlike haptics separate a high-plus anterior lens from a posterior minus lens. With accommodative effort, the capsular bag expands and the springs express kinetic energy, which might allow the optics to separate as the anterior lens moves forward.

RECENT FINDINGS

This article seeks to clarify and distinguish the concepts of true accommodation and pseudo accommodation. Current designs of accommodative IOLs are supposed to work by the focus-shift principle to allow true pseudophakic accommodation. Studies that biometrically assessed optic shift found no or only low amplitudes of forward movement. The amount of forward movement, if present, was highly variable between patients. To date, most studies present psychophysical data for the proof of concept, which alone seems insufficient. Capsule bag performance and posterior capsule opacification with accommodative IOLs seem worse than those with standard intraocular lenses.

SUMMARY

The potential clinical benefits of accommodative IOL technology for both cataract patients and refractive patients may place accommodative IOLs in a competitive position with multifocal IOL technology.

Spring constants of capsular tension rings

PURPOSE

To determine the spring constants of several types of capsular tension rings (CTRs).

SETTING

Department of Ophthalmology, Johannes Gutenberg-University, Mainz, Germany.

METHODS

Fourteen models of CTRs provided by 9 companies were tested; all were 11.0 mm in diameter. The CTRs were positioned in a special retainer of a material-testing machine and compressed at a constant speed of 10.0 mm per minute. The distance and force values were recorded, and each CTR model was tested 3 times using a new specimen each time. The resulting measurements were used to calculate a mean spring constant for each CTR model.

RESULTS

All tested CTRs showed linear proportionality between force and compression distance. Test results were repeatable and precise. Capsular tension rings of the same model had comparable mechanical properties, and different models had different mean spring constants ranging from 0.8162 to 4.5501 mN/mm.

CONCLUSIONS

The spring constant of a CTR is a suitable mechanical characteristic to facilitate the choice of CTR model. A CTR with a low spring constant may be advantageous for the management of zonular dialysis, whereas a CTR with a higher spring constant may reduce capsular bag shrinkage more effectively.

A mathematical model of factors that influence the performance of accommodative intraocular lenses

In this work a mathematical model of capsule movement during pseudophakic accommodation is described to allow identification and evaluation of factors that may explain the variation in effect of accommodative intraocular lenses (IOLs) between patients. The model assumes that increasing vitreous pressure pushes the lens capsule forward as a circular diaphragm and that this movement is from a fixed fulcrum. With an IOL in situ, the capsule is taken to have a non-uniform thickness due to the presence of the anterior capsulorhexis. The model assumes a uniform capsular elasticity and ignores contributions from cellular elements such as posterior capsule opacification. Using our model and a regression formula to calculate capsular bag size, taking into account axial length and keratometry values, we are able to predict accommodative effect in individual patients. By simple geometry we have developed a mathematical model to identify variables that are important in pseudophakic accommodation. It provides the basis for the development of a more complex model that would address the movement of a lens taking into account the influence of the zonular system during accommodation.