Capsular bag opacification with a new accommodating intraocular lens

BCLA CLEAR Presbyopia: Definitions

Presbyopia is often the first sign of ageing experienced by humans. Standardising terminology and adopting it across the BCLA CLEAR Presbyopia reports, improves consistency in the communication of the evidence-based understanding of this universal physiological process. Presbyopia can be functionally and psychologically debilitating, especially for those with poor access to eyecare. Presbyopia was defined as occurring when the physiologically normal age-related reduction in the eye's focusing range reaches a point that, when optimally corrected for far vision, the clarity of vision at near is insufficient to satisfy an individual's requirements. Accommodation is the change in optical power of the eye due to a change in crystalline lens shape and position, whereas pseudo-accommodation is the attainment of functional near vision in an emmetropic or far-corrected eye without changing the refractive power of the eye. Other definitions specific to vision and lenses for presbyopia were also defined. It is recommended that these definitions be consistently adopted in order to standardise future research, clinical evaluations and education.

Influence of the CleaRing intraocular open capsule device on refractive predictability in cataract surgery

BACKGROUND

The marked improvement in cataract surgery and intraocular lens (IOL) quality has led to a decline in posterior capsular opacification (PCO) incidence; however, PCO remains a common complication of cataract surgery. The CleaRing intraocular capsule open device (IOCD) decreases PCO incidence. We aimed to investigate the influence of the CleaRing IOCD on refractive predictability in cataract surgery.

METHODS

We conducted this prospective pilot study at the Wolfson Medical Center, Holon, Israel. Ten eyes of patients who underwent cataract surgery and insertion of an IOL after IOCD implantation into the capsular bag were included. All patients completed 12 months of follow-up, including refraction, measurement of uncorrected (UDVA) and best-corrected distance visual acuity (CDVA), slit-lamp biomicroscopy, and ultrasound biomicroscopy.

RESULTS

All the surgeries were uneventful, with no postoperative complications. The IOL was centred in the device and bag in all cases. The mean prediction error at 1 and 12 months postoperatively was +0.28 ± 0.32 D and +0.50 ± 0.32 D, respectively. The mean UDVA was 0.17 ± 0.13 and 0.15 ± 0.11 logMAR, and the mean CDVA was 0.04 ± 0.10 and 0.04 ± 0.06 logMAR, respectively. The manifest refractive cylinders at 12 months postoperatively were compatible with corneal astigmatism.

CONCLUSIONS

Implantation of the IOCD resulted in a slight, predicted, and stable hyperopic shift with a low standard deviation. The standard deviation of the prediction error demonstrated excellent refractive accuracy and predictability using the IOCD, which was as low as 0.32 D at the 12-month follow-up.

Pediatric cataract surgery: Rate of secondary visual axis opacification depending on intraocular lens type

PURPOSE

To assess the time course of secondary visual axis opacification (VAO) that led to additional surgery after primary intraocular lens (IOL) implantation in children and to describe further surgical outcomes. Comparison of different lens types.

DESIGN

Single center, retrospective analysis of children aged 1-14 years who underwent cataract surgery with primary IOL implantation. The surgical technique was either in-bag IOL placement with primary posterior capsulotomy and anterior vitrectomy or bag-in-lens IOL placement. We excluded eyes with visually significant ocular comorbidities.

SUBJECTS

Total of 135 eyes of 95 children. Of these, 64 had received an acrylic three-piece IOL, 51 an acrylic single-piece IOL, and 20 an acrylic single-piece bag-in-lens IOL. The median ages at surgery were 53 months (IQR 35-75), 52 months (27-65), and 60 months (40-84) in the 3-piece, 1-piece, and bag-in-lens group, respectively.

METHODS

Analysis of medical records. We used the Kaplan-Meier method and a cox proportional hazards model with pre-defined adjustments for age at surgery, year of surgery, and socioeconomic deprivation (GISD score by postal code) to analyze VAO-free survival by lens type. Patients were invited to attend a clinical visit to achieve longer follow-ups.

MAIN OUTCOME MEASURES

The rate of survival without VAO that required clearing of the visual axis after cataract surgery with primary IOL implantation. Any other surgical complications.

RESULTS

The overall median follow-up was 19 months (IQR 3-58). There were 13 cases of VAO, occurring at a median of 10 months (IQR 10-12) after surgery. Of these, 1 eye had a 3-piece in-bag IOL, 10 eyes had 1-piece in-bag IOLs, and 2 eyes had bag-in-lens IOLs. The adjusted hazard ratio was 32.8 (95% CI: 3.3-327, p=0.003) for 1-piece acrylic IOLs and 19.6 (1.22-316, p=0.036) for bag-in-lens IOLs, compared to 3-piece acrylic in-bag IOLs. Two eyes with bag-in-lens surgery (10%) had an iris capture. There was one case of endophthalmitis. We found no cases of postoperative retinal detachment or new glaucoma.

CONCLUSIONS

Children with secondary visual axis opacification that required a procedure to clear the visual axis generally presented within fifteen months. Opacification rates were lowest when a 3-piece acrylic IOL was used.

Long-term uveal and capsular biocompatibility of a new fluid-filled, modular accommodating intraocular lens

PURPOSE

To evaluate long-term uveal and capsular biocompatibility of a new fluid-filled modular accommodating intraocular lens (IOL) consisting of base and fluid lenses.

SETTING

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

DESIGN

Experimental study.

METHODS

Bilateral phacoemulsification was performed on 8 rabbits; 1 eye received the test IOL (Juvene) and the other a hydrophobic acrylic control IOL (SA60AT). Slitlamp examinations were performed at postoperative weeks 1 and 4, and at months 2, 3, and 6. The rabbits were killed humanely at 6 months. After gross examination from the Miyake-Apple view, IOLs were removed for implant cytology. All globes were then processed for histopathologic examination.

RESULTS

Uveal biocompatibility was similar between test and control IOLs up to 6 months postoperatively. Anterior capsule opacification appeared absent in the test group, and posterior capsule opacification (PCO) was significantly less in comparison with the control group throughout the study. At 6 months, central PCO was scored as 0.12 ± 0.23 with test IOLs and as 4.0 ± 0 with control IOLs (P < .0001, 2-tailed t test: paired 2-sample for means). Histopathologic examination confirmed the relative lack of capsular opacification in test eyes in comparison to controls and the absence of toxicity in any eye.

CONCLUSIONS

Six weeks in the rabbit model corresponds to approximately 2 years in the human eye for PCO. In this model, the Juvene IOL maintained an open and expanded capsular bag, preventing overall capsular bag opacification while retaining excellent uveal and capsular biocompatibility.

Explantation/exchange of the components of a new fluid-filled, modular, accommodating IOL

PURPOSE

To evaluate the ease of replacement and capsular stability of a new fluid-filled, modular, accommodating intraocular lens (IOL) system composed of a monofocal base lens with a fluid lens clipped inside of it.

SETTING

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

DESIGN

Experimental study.

METHODS

Five New Zealand rabbits underwent bilateral phacoemulsification with implantation of the test lens (Juvene, LensGen, Inc.) in both eyes (4 rabbits), or a control IOL in 1 eye (AcrySof, Alcon Laboratories, Inc.) and the test IOL in the other (1 rabbit). At 2 weeks, the 4 rabbits with bilateral Juvene IOLs had the clipped-in fluid lens exchanged for a new fluid lens in 1 eye, and the base and fluid lenses exchanged for a control lens in the contralateral eye. Slitlamp examinations were performed weekly for 4 weeks. The globes were enucleated and evaluated with ultrasound biomicroscopy, grossly from the posterior Miyake-Apple view, and histopathologically.

RESULTS

Explantation/exchange of the fluid lens was considered straightforward by the surgeon. Explantation of the base lens (4) was also safely performed, albeit more demanding, without any signs of damage to the capsular bag under clinical, ultrasound biomicroscopy, and pathological examination in the exchanged eyes. Less capsular bag opacification was observed with the Juvene lens system.

CONCLUSIONS

Explantation/exchange of the fluid lens component, or both fluid and base lenses, of this new lens system can be safely accomplished if necessary, because of its modular design and the relative lack of postoperative capsular bag opacification associated with it.

Intraocular Lenses: Overview of Designs, Materials, and Pathophysiologic Features

This article provides an overview of intraocular lenses (IOLs) currently used in cataract surgery. Aspects presented include design features related to IOL construction and sites of fixation; optic, filter, and haptic materials; as well as pathophysiologic features of uveal biocompatibility, capsular biocompatibility, and postoperative IOL opacification. This overview also includes supplementary (add-on; piggyback) lenses implanted in eyes that are already pseudophakic and considerations on IOLs used in the pediatric population. Different IOLs are made available to surgeons each year, including lenses with increasingly complex design characteristics owing to advancements in manufacturing and surgical techniques.

Long-term uveal and capsular biocompatibility of a novel modular intraocular lens system

BACKGROUND

We evaluated the long-term biocompatibility and safety of a new modular posterior chamber intraocular lens (IOL) system in rabbit eyes.

METHODS

Seven New Zealand rabbits underwent bilateral phacoemulsification with placement of the modular IOL in OD and a control IOL (SA60AT) in OS. Slit-lamp examinations were performed at postoperative weeks 1, 2, 3, 4, 6 and 8 and months 3 and 6. All rabbits were then sacrificed and eyes enucleated. The eyes were examined grossly from the Miyake-Apple view. Selected IOLs were explanted and underwent surface staining for implant cytology. All globes were then sectioned and processed for histopathological examination.

RESULTS

The modular IOL remained stable in all seven rabbits through the entire follow-up period. Biocompatibility was better than the control lens at six months postoperatively, on account of less extensive synechiae formation as assessed by slit-lamp examination. At the six-week examination, posterior capsule opacification (PCO) was significantly better in the test group (scored as 1.71 ± 0.8 versus 3.28 ± 0.48 in the control group, p = 0.0008). On gross examination with the Miyake-Apple view, Soemmering's ring formation was significantly better in the test group, (5.14 ± 1.57 versus 10.85 ± 1.95 in the control group, p = 0.002).

CONCLUSION

Previous studies showed that explantation/exchange of the modular system optic was safer and easier than with a standard IOL. The new modular IOL system has demonstrated better long-term biocompatibility compared to the control lens at six months postoperatively in the rabbit model.

Further Enhancement of Intraocular Open-Capsule Devices for Prevention of Posterior Capsule Opacification

Purpose

We improve the intraocular open-capsule devices (IOCD) for the prevention of posterior capsule opacification (PCO).

Methods

A total of 45 New Zealand rabbit eyes were divided into six similar groups after crystalline lens evacuation. Each group was implanted with a hydrophilic intraocular lens (IOL) and a hydrophilic IOCD of different designs. In the first experiment (Part A), a square design ring with and without large apertures was compared to a round design ring without apertures. In the second experiment (Part B), a square design ring with large apertures was compared to square design IOCDs with small apertures of high and low density. PCO and Soemmering's ring were evaluated clinically, by the Miyake Apple view, and histologically. The results were compared to a control group of eyes implanted with a hydrophilic IOL only.

Results

All devices showed significant prevention of PCO and Soemmering's ring compared to the control group. Part A: the square design with apertures had the lowest level of peripheral lens epithelial cells proliferation (protrusions). Part B: modifying the size and density of the apertures had no influence on those protrusions.

Conclusions

The IOCD significantly reduced the rate of PCO and its precursor, Soemmering's ring. The rings with the square edges and apertures produced the best results. The study was underpowered to determine the influence of the apertures design.

Translational Relevance

The IOCD has the potential to prevent up to 80% of the PCO cases; the most common complication after cataract surgery. The design of the ring is important for its success.

Accommodating Intraocular Lenses

With an explosive increase in the worldwide prevalence of presbyopia, development of an accommodating intraocular lens (IOL) with expansive accommodative amplitude remains the holy grail in lens-based refractive surgery. A dynamic change in the dioptric power of the eye can be accomplished by various strategies alone or in combination, including changes in the position, shape, or refractive index of a single- or dual- optic IOL. This article reviews the cumulative advances in these various lens designs, along with clinical outcomes and complications of those that have been implanted. The challenges that remain in each cat-egory are also highlighted.

Prevention of postoperative capsular bag opacification using intraocular lenses and endocapsular devices maintaining an open or expanded capsular bag

Postoperative capsule opacification is a multifactorial physiological consequence of cataract surgery that remains the most common complication of this procedure. A literature review that included several intraocular lenses (IOLs) and endocapsular devices studied in our laboratory found that devices maintaining the capsular bag in an open or expanded state were associated with improved bag clarity. This observed effect likely occurs secondary to the complex interactions of myriad mechanisms, which include formation of a barrier to lens epithelial cell (LEC) migration, mechanical compression of residual LECs, mechanical stretch at the level of the capsule equator, maintenance of overall bag contour, and enhanced endocapsular circulation of aqueous humor. We review the designs of endocapsular devices and IOLs that minimize the degree of postoperative capsule opacification by preventing capsular bag collapse and discuss the underlying mechanisms that contribute to this phenomenon.

FINANCIAL DISCLOSURE

None of the authors has a financial or proprietary interest in any material or method mentioned.

Long-term uveal and capsular biocompatibility of a new accommodating intraocular lens

PURPOSE

To evaluate long-term uveal and capsular biocompatibility of a new accommodating intraocular lens (IOL).

SETTING

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

DESIGN

Experimental study.

METHODS

Bilateral phacoemulsification was performed in 14 rabbits; 1 eye received the accommodating IOL (Fluidvision) and the other received a hydrophobic acrylic control IOL. Slitlamp examinations were performed at postoperative weeks 1 to 4 and months 2, 3, 4, and 6. Six rabbits were humanely killed at 2 months and 8 rabbits at 6 months. After gross examination with the Miyake-Apple view, selected IOLs were removed for implant cytology. All globes were then sectioned and processed for histopathologic examination.

RESULTS

Uveal biocompatibility of study and control IOLs was similar in clinical and pathologic examinations up to 6 months postoperatively. In the study group, anterior capsule opacification appeared absent and posterior capsule opacification (PCO) was significantly less than in the control group. At the gross examination at 6 months, central PCO was 0.8 ± 0.5 (SD) in the study IOLs and 3.7 ± 0.4 in the control IOLs (P < .0001, 2-tailed paired t test). Histopathologic examination confirmed the relative lack of capsule opacification in study eyes compared with controls and the absence of untoward inflammatory reaction or toxicity in all eyes.

CONCLUSIONS

The accommodating IOL maintained an expanded capsular bag secondary to the large size of the haptic elements without significant contact with the anterior capsule. This appeared to prevent overall capsular bag opacification and to retain uveal and capsular biocompatibility.

Developments in the correction of presbyopia II: surgical approaches

PURPOSE

To discuss the various static and dynamic surgical approaches which attempt to give presbyopes good vision at far, intermediate and near viewing distances.

CONTENT

Static methods broadly adopt the same optical techniques as those used in presbyopic contact lens correction and aim to satisfy the needs of the presbyope by increasing binocular depth-of-focus, often using monovision as well as simultaneous-imagery. Dynamic methods generally attempt to make use of at least some of the still-active elements of the accommodation system. They include procedures which are supposed to modify the relative geometry of the ciliary muscle and lens, or which reduce the stiffness of the presbyopic lens either by replacing it with other natural or man-made material or by subjecting it to femtosecond laser treatment. Alternatively the natural lens may be replaced by some form of intraocular lens which changes power as a result of forces derived from the still-active ciliary muscle, zonule and capsule, or other sources.

CONCLUSIONS

At present, multifocal intraocular lenses appear to offer the most consistent and reliable surgical approach to surgical presbyopic correction. They have obvious advantages in convenience and stability over optically-similar, simultaneous-image presbyopic contact lenses but this must be balanced against their relative inflexibility in cases of patient dissatisfaction. Dynamic methods remain largely experimental. Although some approaches show promise, as yet no method has demonstrated a reliable, long-term ability to correct distance refractive error and to appropriately change ocular power in response to changes in viewing distance over the normal range of interest.