Effect of square-edged intraocular lenses on neodymium:YAG laser capsulotomy rates in the United States

The evaluation of the effect of Nd-YAG capsulotomy on posterior ocular vascular structures by Optical coherence tomography angiography

BACKGROUND

We aimed to examine the changes in retinal, choroidal and optic nerve head vascular structures after Nd-YAG laser application due to posterior capsule opacification after cataract surgery by Optical coherence tomography angiography (OCTA).

METHODS

Fifteen eyes of 15 patients who have posterior capsule opasification and underwent Nd-YAG laser capsulotomy were included in the study. OCTA imagings of patients were made before and one hour, one week and one month later after the laser procedure.

RESULTS

No significant change was determined before and after capsulotomy in macular thickness measurements, flow areas and vessel densities (all p > 0.05). Optic nerve head vessel densities and flow areas didn't differ preoperatively and postoperatively (p > 0.05).

CONCLUSIONS

Nd-YAG laser capsulotomy for posterior capsule opacification has no detectable effect on macular and optic nerve flows and vessel densities.

Cataract inhibitors: Present needs and future challenges

Cataracts result from opacification of the ocular lens and represent the leading cause of blindness worldwide. After surgical removal of the diseased lens material and implantation of an artificial intraocular lens, up to 50% of cataract patients develop a secondary lens defect called posterior capsular opacification (PCO). While vision can be restored in PCO patients by a laser-mediated capsulotomy, novel therapies involving inhibition of aldose reductase are now being developed to prevent PCO development and complications of laser capsulotomy. A question we wished to address was whether cataract surgeons believe there is an unmet need for a preventative PCO therapy, whether they would prescribe such a therapy were it available, and to assess their perceptions regarding the benefits of and obstacles to adopting novel PCO therapies in the place of laser capsulotomy. We gathered perspectives from adult, pediatric, and veterinary cataract surgeons using an online questionnaire. From 161 surgeon responses, we found that the majority of adult, pediatric, and veterinary cataract surgeons (78% n = 35, 88% n = 37, and 96% n = 71 respectively) believed there is an unmet need for preventative PCO therapy, with more than 95% expressing interest in incorporating such therapy into surgical protocols. Perceived benefits included optimizing visual outcomes, avoiding the need for additional procedures, eliminating complications related to neodymium:yttrium-aluminum-garnet laser, preserving the posterior capsule particularly in patients receiving multifocal intraocular lens implants, providing a viable solution for PCO in animals, and using it in developing countries that lack access to neodymium:yttrium-aluminum-garnet lasers. Perceived obstacles included potential lack of reimbursement by insurance companies, and the need for strong efficacy and safety profiles. Among adult surgeons, 70% (n = 31) indicated that preventative PCO therapy could add value to premium intraocular lens packages. Our studies revealed that cataract surgeons overwhelmingly support the development of preventative PCO therapy, and that clinical trials will play a critical role to test the safety and efficacy of specific therapeutic agents.

A Review of Complicated Cataract in Retinitis Pigmentosa: Pathogenesis and Cataract Surgery

Retinitis pigmentosa (RP) is a set of inherited retinal degenerative diseases that affect photoreceptor and retinal pigment epithelial cells (RPEs), possibly associated with some ocular complications, including cataract. The complicated cataract formation is most likely the result of RP-related inflammation response, and the most common morphology category is posterior subcapsular cataract (PSC). Despite the absence of curative pharmacologic treatment, phacoemulsification with intraocular lens implantation to deal with opacification in the lens is preferred due to the considerable visual outcomes. However, the incidence of intraocular and postoperative complications is higher in RP patients than those without, including intraoperative phototoxic retinal damage, posterior capsular opacification (PCO), capsular contraction syndrome (CCS), pseudophakic cystoid macular edema (PCME), increased postoperative intraocular pressure (IOP), and intraocular lens (IOL) dislocation. Hence, it needs much attention to surgery progress and close follow-up. In this review, we discuss the current understanding of RP patients with complicated cataracts from morphology to potential pathogenesis to cataract surgical procedure and provide a concise description and the recommended management of related surgery complications to broaden the knowledge and lower the latent risks to yield better clinical outcomes.

Use of Human Pluripotent Stem Cells to Define Initiating Molecular Mechanisms of Cataract for Anti-Cataract Drug Discovery

Cataract is a leading cause of blindness worldwide. Currently, restoration of vision in cataract patients requires surgical removal of the cataract. Due to the large and increasing number of cataract patients, the annual cost of surgical cataract treatment amounts to billions of dollars. Limited access to functional human lens tissue during the early stages of cataract formation has hampered efforts to develop effective anti-cataract drugs. The ability of human pluripotent stem (PS) cells to make large numbers of normal or diseased human cell types raises the possibility that human PS cells may provide a new avenue for defining the molecular mechanisms responsible for different types of human cataract. Towards this end, methods have been established to differentiate human PS cells into both lens cells and transparent, light-focusing human micro-lenses. Sensitive and quantitative assays to measure light transmittance and focusing ability of human PS cell-derived micro-lenses have also been developed. This review will, therefore, examine how human PS cell-derived lens cells and micro-lenses might provide a new avenue for development of much-needed drugs to treat human cataract.

Transzonular capsulo-hyaloidal hydroseparation with optional triamcinolone enhancement: A technique to detect or induce anterior hyaloid membrane detachment for primary posterior laser capsulotomy

Primary posterior laser capsulotomy (PPLC) requires adequate visualization and spacing of the posterior lens capsule (PLC) and anterior hyaloid membrane (AHM). After intraocular lens implantation and watertight incision hydration, the laser is redocked for optical coherence tomography reimaging. If the PLC and AHM are not imaged or interspaced adequately, transzonular capsulo-hyaloidal hydroseparation is attempted by rinsing the zonular fibers with fluid. If the PLC or AHM are still not detected or discernable, an attempt follows to mark the Berger space using diluted triamcinolone acetate. Before hydroseparation, the AHM or PLC are often invisible or variably attached. If structures cannot be defined, triamcinolone-added hydroseparation is often effective in defining the AHM and Berger space. Transzonular capsulo-hyaloidal hydroseparation with an optional triamcinolone acetate addition can initiate or complete AHM detachment and improve visibility and patency of Berger space for augmenting control and feasibility of PPLC.

Aldose Reductase Inhibition Prevents Development of Posterior Capsular Opacification in an In Vivo Model of Cataract Surgery

Purpose

Cataract surgery is a procedure by which the lens fiber cell mass is removed from its capsular bag and replaced with a synthetic intraocular lens. Postoperatively, remnant lens epithelial cells can undergo an aberrant wound healing response characterized by an epithelial-to-mesenchymal transition (EMT), leading to posterior capsular opacification (PCO). Aldose reductase (AR) inhibition has been shown to decrease EMT markers in cell culture models. In this study, we aim to demonstrate that AR inhibition can attenuate induction of EMT markers in an in vivo model of cataract surgery.

Methods

A modified extracapsular lens extraction (ECLE) was performed on C57BL/6 wildtype, AR overexpression (AR-Tg), and AR knockout mice. Immunofluorescent staining for the myofibroblast marker α-smooth muscle actin (α-SMA), epithelial marker E-cadherin, and lens fiber cell markers αA-crystallin and Aquaporin 0 was used to characterize postoperative PCO. Quantitative reverse transcription PCR (qRT-PCR) was employed to quantify postoperative changes in α-SMA, vimentin, fibronectin, and E-cadherin. In a separate experiment, the AR inhibitor Sorbinil was applied postoperatively and qRT-PCR was used to assess changes in EMT markers.

Results

Genetic AR knockout reduced ECLE-induced upregulation of α-SMA and downregulation of E-cadherin. These immunofluorescent changes were mirrored quantitatively in changes in mRNA levels. Similarly, Sorbinil blocked characteristic postoperative EMT changes in AR-Tg mice. Interestingly, genetic AR knockout did not prevent postoperative induction of the lens fiber cell markers αA-crystallin and Aquaporin 0.

Conclusions

AR inhibition prevents the postoperative changes in EMT markers characteristic of PCO yet preserves the postoperative induction of lens fiber cell markers.

Dual function of TGFβ in lens epithelial cell fate: implications for secondary cataract

The most common vision-disrupting complication of cataract surgery is posterior capsule opacification (PCO; secondary cataract). PCO is caused by residual lens cells undergoing one of two very different cell fates: either transdifferentiating into myofibroblasts or maturing into lens fiber cells. Although TGFβ has been strongly implicated in lens cell fibrosis, the factors responsible for the latter process have not been identified. We show here for the first time that TGFβ can induce purified primary lens epithelial cells within the same culture to undergo differentiation into either lens fiber cells or myofibroblasts. Marker analysis confirmed that the two cell phenotypes were mutually exclusive. Blocking the p38 kinase pathway, either with direct inhibitors of the p38 MAP kinase or a small-molecule therapeutic that also inhibits the activation of p38, prevented TGFβ from inducing epithelial-myofibroblast transition and cell migration but did not prevent fiber cell differentiation. Rapamycin had the converse effect, linking MTOR signaling to induction of fiber cell differentiation by TGFβ. In addition to providing novel potential therapeutic strategies for PCO, our findings extend the so-called TGFβ paradox, in which TGFβ can induce two disparate cell fates, to a new epithelial disease state.

Experimental models for posterior capsule opacification research

Millions of people worldwide are blinded due to cataract formation. At present the only means of treating a cataract is through surgical intervention. A modern cataract operation involves the creation of an opening in the anterior lens capsule to allow access to the fibre cells, which are then removed. This leaves in place a capsular bag that comprises the remaining anterior capsule and the entire posterior capsule. In most cases, an intraocular lens is implanted into the capsular bag during surgery. This procedure initially generates good visual restoration, but unfortunately, residual lens epithelial cells undergo a wound-healing response invoked by surgery, which in time commonly results in a secondary loss of vision. This condition is known as posterior capsule opacification (PCO) and exhibits classical features of fibrosis, including hyperproliferation, migration, matrix deposition, matrix contraction and transdifferentiation into myofibroblasts. These changes alone can cause visual deterioration, but in a significant number of cases, fibre differentiation is also observed, which gives rise to Soemmering's ring and Elschnig's pearl formation. Elucidating the regulatory factors that govern these events is fundamental in the drive to develop future strategies to prevent or delay visual deterioration resulting from PCO. A range of experimental platforms are available for the study of PCO that range from in vivo animal models to in vitro human cell and tissue culture models. In the current review, we will highlight some of the experimental models used in PCO research and provide examples of key findings that have resulted from these approaches.

EGFR inhibitor Gefitinib attenuates posterior capsule opacification in vitro and in the ex vivo human capsular bag model

PURPOSE

Posterior capsule opacification (PCO) occurs as a common complication after cataract surgery. Gefitinib is a selective inhibitor of the epidermal growth factor receptor (EGFR) which represents a potential pharmacological target for PCO prevention. In this in vitro study, we assessed the effect and biocompatibility of Gefitinib in PCO prophylaxis.

METHODS

The effect of Gefitinib on the key pathological features of PCO was assessed in vitro. We determined growth in the human capsular bag model, prepared from sixteen cadaver eyes that underwent sham cataract surgery. Furthermore, two lens epithelial cell lines, HLE-B3 and FHL-124, were used to determine concentration-based effects on cell proliferation. In addition, cell-migration, matrix-contraction, and cell spreading were investigated. To exclude toxic concentrations, Gefitinib was assessed for its biocompatibility on six different human ocular cell types from the anterior and posterior segment of the eye.

RESULTS

Gefitinib significantly increased the time until confluence of the capsular bag compared to controls (p < 0.001)). In both human lens epithelial cell lines (HLE-B3 and FHL-124), proliferation decreased significantly and as equally strong after incubation with Gefitinib (p < 0.001), as did chemotactic migration (p = 0.004), matrix contraction (p = 0.001), and cell-spreading (p = 0.001). At the IC50 concentration, Gefitinib was well tolerated by six different human ocular cell types of the anterior and posterior segment.

CONCLUSION

The specific EGFR inhibitor Gefitinib might become of clinical relevance in PCO prophylaxis as it attenuated cellular growth and other pathological PCO factors in the ex vivo human capsular bag model and in two human lens epithelial cell lines, while showing good biocompatibility in vitro.

In vitro growth of lens epithelial cells from cataract patients - association with possible risk factors for posterior capsule opacification

AIM

Inter-individual differences in intrinsic proliferative capacity of lens epithelial cells may have importance for the risk of developing posterior capsule opacification (PCO) after cataract surgery. The purpose of the present study was to determine growth of human lens epithelial cells (HLEC) in culture and investigate possible associations with clinical characteristics of the donors, such as age, sex, pseudoexfoliation, uveitis and diabetes.

METHODS

Pieces of lens capsule and adhering lens epithelial cells were obtained through capsulorhexis at cataract surgery. Specimens were cultured in a humidified CO2-incubator using standard culture medium and 5% fetal calf serum for two weeks after which cultured cells were stained with carboxy-fluorescein diacetate succinimidyl ester. Image processing software was used to determine the area of the confluent epithelial cell layer in relation to the size of the original capsule specimen.

RESULTS

The increase in area of confluent HLEC showed a negative correlation with diabetes at the first week after surgery. Lower age and female sex showed border-line significant associations with a higher rate of cell proliferation. The presence of pseudoexfoliation in vivo did not significantly affect cell growth in culture postoperatively. Nor did installation of xylocain in the anterior chamber during surgery.

CONCLUSION

Diabetes is associated with lower rate of proliferation of lens epithelial cells in culture. The lack of strong correlations between in vitro growth and known risk factors for PCO in the donors suggest that other factors than the proliferative capacity of the cells per se are important for PCO formation.

The Effect of ND:YAG Laser Posterior Capsulotomy Size on Refraction, Intraocular Pressure, and Macular Thickness

Purpose. The aim of this study is to examine the influence of capsulotomy size on, spherical equivalent (SE), intraocular pressure (IOP), and macular thickness. Materials and Methods. Sixty-eight patients were examined preoperatively and 1, 4, and 12 weeks after Nd:YAG capsulotomy. Patients were divided into two groups based on the postoperative capsulotomy size. Changes in SE, IOP, and macular thickness were compared between two groups. Results. We found a higher hyperopic shift in large capsulotomy group. In both groups 1 and 2, IOP increased 1 week postoperatively. Intraocular pressure rise in group 2 was higher than in group 1. Both groups had increased macular thickness at 1 week postoperatively. The degree of macular thickening was similar in group 1 and group 2. Comment. Patients who underwent a larger capsulotomy have a higher hyperopic shift and IOP elevation. Rise in macular thickness was similar in large and small capsulotomy groups.

Posterior capsular opacification in patients with pseudoexfoliation syndrome: a long-term perspective

PURPOSE

To compare posterior capsular opacification in patients with and without pseudoexfoliation syndrome 6-7 years following surgery.

METHODS

Forty-four eyes of 44 patients with pseudoexfoliation syndrome who underwent cataract surgery with phacoemulsification in 2001 and 2002 were available for follow-up in 2008. These patients were compared to 86 age- and gender-matched patients (86 eyes) without pseudoexfoliation syndrome who had surgery during the same time period. Posterior capsule opacification was assessed using digital retroillumination photography. The images were analysed with a software program (POCOman) to determine the extent and severity of the capsular opacification.

RESULTS

Percentage and severity of posterior capsular opacification within the central 4.0 and 1.3 mm of the optical zone were compared in eyes with and without pseudoexfoliation syndrome. Neither of these results were statistically significant. Before the re-examination in 2008, neodymium:yttrium-aluminium-garnet laser posterior capsulotomy had been conducted in 16% (n = 7) of eyes with pseudoexfoliation syndrome, as well as in 16% (n = 14) of eyes without pseudoexfoliation syndrome.

CONCLUSION

Our study indicates that, with phacoemulsification, development of long-term posterior capsular opacification is not increased in patients with pseudoexfoliation syndrome after uncomplicated cataract surgery.

Outcome of capsulotomy in patients with low vision and posterior capsule opacification

PURPOSE

To investigate the functional outcome, as defined using the Catquest questionnaire, for patients with posterior capsule opacification (PCO) and low corrected distance visual acuity (CDVA), after capsulotomy.

METHODS

Thirty-one patients with PCO and visual acuity ≥ 0.6 (log MAR, ≤ 0.25 decimal notation) in the PCO eye were examined before and 1 month after capsulotomy. An ophthalmic examination, procuring of a digital image of the posterior lens capsule and completion of Catquest were carried out.

RESULTS

Mean CDVA (p < 0.001), disabilities in daily life (p = 0.004), activity (p = 0.012), symptoms of glare (p = 0.003) and satisfaction with vision (p < 0.001) all improved after capsulotomy. Sixty-five per cent of patients had good or very good benefit and 23% questionable or no benefit. The group with moderate benefit was only 6%. Compared with patients with PCO and better visual acuity, the number of patients with good benefit was greater than the number with moderate benefit.

CONCLUSIONS

Most patients with PCO and low CDVA reported improved visual function in daily life as defined using Catquest, after capsulotomy. The group with moderate benefit was small, indicating that the improvement was either substantial or negligible.

Nd:YAG laser capsulotomy: a survey of UK practice and recommendations

PURPOSE

To determine national trends in YAG laser capsulotomy practice in the NHS.

METHODS

A total of 300 consultants were randomly selected, based on a list from the Royal College of Ophthalmologists, to receive a postal questionnaire. It included 10 questions about YAG capsulotomy technique and postcapsulotomy management.

RESULTS

A total of 158 (53%) replies were received; 132 (83.5%) questionnaires were completed correctly. Most consultants dilate the pupil prior to treatment (98.5%) and use contact lens (87.9%), with 63.5% reporting using contact lenses for more than one indication. Nearly half of the consultants used cruciate laser pattern (47.0%). Most aimed for capsulotomy size larger than undilated pupil size (64.4%). A total of 42.4% used postoperative steroid drops, 61.8% for 1 week. Half used postlaser intraocular pressure-lowering drops with the majority used as 1-stat dose (85.1%). A total of 60% are not reviewing cases. Cases reviewed are mostly seen by doctors, with 50% reviewed 1 month postlaser.

CONCLUSIONS

Though commonly practiced, there is still considerable variation in YAG laser capsulotomy practice among NHS consultant ophthalmologists. Evidence-based guidelines are warranted to lessen any unnecessary complications.

Effect of delivery of MMP inhibitors from PDMS as a model IOL material on PCO markers

Posterior capsule opacification (PCO) or secondary cataract formation, following intraocular lens implantation, is a significant complication affecting an estimated 28% of cataract patients. Matrix metalloproteinases (MMPs) have been demonstrated to play a role in the formation of anterior subcapsular cataracts and it has been shown that the presence of MMP inhibitors (MMPI) decreases subcapsular cataract formation ex vivo. Since the mechanisms responsible for anterior subcapsular cataract formation and posterior capsule opacification are similar, it is reasonable to suggest that MMP inhibitors may also mitigate PCO. One of the most effective ways of delivering the inhibitors may be from the implanted intraocular lens (IOL) material itself. In the current work, delivery of three different MMP inhibitors from silicone rubber as a model IOL material was examined. Loading methods were developed which allowed continuous release of active MMPI for periods of over 5 months in some cases. Reduced migration rates were observed in human lens epithelial cells in vitro, suggesting that an effect on PCO may be possible. While further studies are necessary to tune the systems to achieve the desired rates of release, this work demonstrates that delivery of MMPI from silicone IOL materials has the potential to decrease the incidence of PCO.

Ten-year longitudinal visual function and Nd: YAG laser capsulotomy rates in patients less than 65 years at cataract surgery

PURPOSE

To investigate the longitudinal subjective and objective visual functional results in adult cataract patients younger than 65 years at surgery. To evaluate the 10-year cumulative incidence of neodymium-yttrium-aluminum-garnet (Nd:YAG) laser treatment.

DESIGN

A prospective, longitudinal, population-based cohort study.

METHODS

The study comprised 116 patients younger than 65 years who had cataract surgery during 1 year at Norrlands University Hospital, Umeå, Sweden. Most patients (94%) had received implantation with a hydrophobic acrylic intraocular lens. Evaluated were visual acuity (VA) and visual function questionnaire (VF-14) results before and after surgery. A comparison with patients 65 years or older at surgery was made. Ten years later, 102 survivors were offered eye examinations and again asked to fill out the questionnaire. Past Nd:YAG laser treatment, as well as high- and low-contrast VA results, were analyzed.

RESULTS

Ten years postoperatively, 37% of the patients under 65 at surgery had been treated with Nd:YAG in comparison to 20% of the older patients. The cumulative incidence for not having Nd:YAG over 10 years was 72% for those under 65 and 85% for the patients 65 years or more at surgery. Eighteen percent of the younger patients had lost more than 0.1 logarithm of the minimal angle of resolution (logMAR) units of the operated eye, compared with 37% of the older (P = .00003). A reduction in VF-14 score of 10 points or more was found in 9% of the younger and 28% of the older cataract surgery patients (P = .00004).

CONCLUSION

Ten years after surgery, subjective and objective visual function remained stable in most patients younger than 65 years at surgery. More than one-third had received a posterior capsulotomy. Only a few patients with posterior capsular opacification requiring Nd:YAG were untreated at the 10-year follow-up.

Clinical consequences of acrylic intraocular lens material and design: Nd:YAG-laser capsulotomy rates in 3 x 300 eyes 5 years after phacoemulsification

Background/aims

To investigate the incidence of Nd:YAG-laser treatment for posterior capsular opacification (PCO) over a period of 5 years from phacoemulsification in an unselected population, comparing outcomes for three acrylic intraocular lenses (IOLs).

Methods

Retrospective longitudinal cohort study comprising 900 eyes. Three subgroups of 300 eyes, receiving the AR40, AR40e (Abbott Medical Optics, Santa Ana, California), or BL27 (Bausch & Lomb, Rochester, New York) IOL respectively, were compared. Data on patient age, gender, IOL type, dates of cataract surgery, Nd:YAG-laser treatment and/or death, and visual acuities before/after cataract surgery/Nd:YAG-laser treatment were collected from five sources: cataract operation register, patient administration system, quality control system for cataract operations, Nd:YAG-laser treatment register and clinical patient records.

Results

216 eyes (24%) received Nd:YAG-laser treatment over a 5-year period. Statistically significant differences (p<0.001, χ² test) were found between treatment rates for the three IOLs: AR40 73 eyes (24%), BL27 91 eyes (30%) and AR40e 52 eyes (17%). Eyes of patients who died during the follow-up period had fewer treatments (23/266, 8.6%) than eyes of patients living (193/634, 30%) at the end of the follow-up period.

Conclusion

In comparison with a hydrophobic acrylic IOL with sharp posterior optic edge, a hydrophilic acrylic IOL was associated with almost twice the number of Nd:YAG-laser treatments over the 5-year period. The results are useful for discussing the economic long-term consequences of choosing an IOL with a design that makes PCO development more or less likely. Caution is advised when applying data from post-mortem PCO studies on living populations.