Erufosine, a phosphoinositide-3-kinase inhibitor, to mitigate posterior capsule opacification in the human capsular bag model

Therapeutic Ophthalmic Lenses: A Review

An increasing incidence of eye diseases has been registered in the last decades in developed countries due to the ageing of population, changes in lifestyle, environmental factors, and the presence of concomitant medical conditions. The increase of public awareness on ocular conditions leads to an early diagnosis and treatment, as well as an increased demand for more effective and minimally invasive solutions for the treatment of both the anterior and posterior segments of the eye. Despite being the most common route of ophthalmic drug administration, eye drops are associated with compliance issues, drug wastage by lacrimation, and low bioavailability due to the ocular barriers. In order to overcome these problems, the design of drug-eluting ophthalmic lenses constitutes a non-invasive and patient-friendly approach for the sustained drug delivery to the eye. Several examples of therapeutic contact lenses and intraocular lenses have been developed, by means of different strategies of drug loading, leading to promising results. This review aims to report the recent advances in the development of therapeutic ophthalmic lenses for the treatment and/or prophylaxis of eye pathologies (i.e., glaucoma, cataract, corneal diseases, or posterior segment diseases) and it gives an overview of the future perspectives and challenges in the field.

A Critical Appraisal of New Developments in Intraocular Lens Modifications and Drug Delivery Systems for the Prevention of Cataract Surgery Complications

Cataract surgery is the commonest ophthalmic surgery worldwide. The replacement of the diseased lens with a synthetic one (intraocular lens-IOL) remains the treatment of choice, despite its potential complications that include infection, inflammation and posterior capsule opacification. The potential for drug delivery via the IOL has been researched extensively over a period of twenty-five years, yet there is very limited progress in transferring the findings from research to everyday practice. The objective of this review is to assess the progress made in the field of IOL lens modifications and drug delivery systems over the past five years. Thirty-six studies that were conducted during the past five years were identified and deemed suitable for inclusion. They were grouped in three broad categories, studies that described new methods for loading a drug onto the IOL, assessment of the effects of drugs that were loaded to the IOL and studies that assessed the effects of non-pharmaceutical modifications of IOLs. While considerable progress is continually being made with regard to methods and materials, there is still little capitalization upon these research studies, with no commercially available IOL-based drug delivery system being available. Close cooperation between researchers in basic sciences (chemistry, physics, materials science and pharmacy), clinical researchers, IOL manufacturers and the pharmaceutical industry is an important prerequisite for further development.

Posterior capsule opacification: What's in the bag?

Cataract, a clouding of the lens, is the most common cause of blindness in the world. It has a marked impact on the wellbeing and productivity of individuals and has a major economic impact on healthcare providers. The only means of treating cataract is by surgical intervention. A modern cataract operation generates a capsular bag, which comprises a proportion of the anterior capsule and the entire posterior capsule. The bag remains in situ, partitions the aqueous and vitreous humours, and in the majority of cases, houses an intraocular lens (IOL). The production of a capsular bag following surgery permits a free passage of light along the visual axis through the transparent intraocular lens and thin acellular posterior capsule. Lens epithelial cells, however, remain attached to the anterior capsule, and in response to surgical trauma initiate a wound-healing response that ultimately leads to light scatter and a reduction in visual quality known as posterior capsule opacification (PCO). There are two commonly-described forms of PCO: fibrotic and regenerative. Fibrotic PCO follows classically defined fibrotic processes, namely hyperproliferation, matrix contraction, matrix deposition and epithelial cell trans-differentiation to a myofibroblast phenotype. Regenerative PCO is defined by lens fibre cell differentiation events that give rise to Soemmerring's ring and Elschnig's pearls and becomes evident at a later stage than the fibrotic form. Both fibrotic and regenerative forms of PCO contribute to a reduction in visual quality in patients. This review will highlight the wealth of tools available for PCO research, provide insight into our current knowledge of PCO and discuss putative management of PCO from IOL design to pharmacological interventions.

Cataract surgeon viewpoints on the need for novel preventative anti-inflammatory and anti-posterior capsular opacification therapies

Purpose: To determine cataract surgeon viewpoints on the efficacy of available therapies/preventatives for two common sequelae of cataract surgery: inflammation and posterior capsular opacification (PCO). Methods: Cataract surgeons practicing worldwide specializing in adult, pediatric and veterinary patients were interviewed between March and August 2018. Results: Ocular inflammation following cataract surgery is treated by either corticosteroids and/or nonsteroidal anti-inflammatories (NSAIDs). Adult and pediatric cataract surgeons are satisfied with current treatments whereas this inflammation is still considered a problem by some in veterinary practice due to its slow resolution. Yttrium-aluminum-garnet (YAG) laser therapy is the PCO treatment of choice for adult cataract surgeons and they are generally pleased with its outcome. However, pediatric cataract surgeons find YAG problematic, especially in patients under 6 years of age, and invasive surgery is often needed to correct PCO/visual axis opacification (VAO). Veterinary ophthalmologists report that YAG is not effective for PCO in animals, especially dogs, due to the density of the fibrotic plaques; 86% of adult and 100% of veterinary and pediatric cataract surgeons surveyed agree that effective anti-PCO therapeutics would improve clinical care. Conclusions: Surgeons treating human patients are pleased with the available treatments for ocular inflammation following cataract surgery, although some veterinary ophthalmologists disagree. The surgeons surveyed agree that PCO/VAO remains an unsolved problem in pediatric and veterinary cataract surgery while the long-term outcome of adult cataract surgery could be improved by additional attention to this issue.

The intraocular lens as a drug delivery device for an epidermal growth factor-Receptor inhibitor for prophylaxis of posterior capsule opacification

PURPOSE

Posterior capsule opacification (PCO) occurs as a common complication after cataract surgery. Erlotinib is an inhibitor of the epidermal growth factor-Receptor and reduces critical cellular events leading to PCO. In this in vitro study, Erlotinib-modified intraocular lenses (IOLs) employed as a drug delivery device have been evaluated for PCO prevention.

METHODS

The IC₅₀ concentration of Erlotinib was determined by using FHL-124 cells. For the human capsular bag model, 40 cadaver eyes underwent sham cataract surgery. Sixteen capsular bags were exposed to the IC₅₀ of Erlotinib. Intraocular lens (IOL) of three different materials was pharmacologically modified and tested in the anterior segment model and implanted into 24 capsular bags. To test for corneal toxicity, pairs of human cornea were exposed to high concentrations of Erlotinib and corneal endothelial cells (CEC) were exposed to the modified IOL. Release kinetics of Erlotinib from the IOL was measured.

RESULTS

IC₅₀ of Erlotinib was determined to be 10 μm. Erlotinib alone (p = 0.002) and when soaked into IOLs (p < 0.001) significantly increased the number of days needed until total cell coverage of the capsular bags in comparison with the control. Modified IOLs mitigated cell growth in the anterior segment model (p < 0.001). No short-term corneal toxicity was observed up to a concentration of 100 μm, and IOLs did not show toxicity on CEC. Erlotinib was released constantly from IOL.

CONCLUSION

Erlotinib might be of clinical relevance in PCO prophylaxis, as its short-term application induces a long-term deceleration of cellular growth. Erlotinib can be introduced into the eye via soaked IOLs.

Comparison of fibrotic response in the human lens capsular bag after femtosecond laser-assisted cataract surgery and conventional phacoemulsification

PURPOSE

To compare the effect of different laser pulse energy settings in femtosecond laser-assisted cataract surgery with that of standard phacoemulsification and no energy at all used on posterior capsule opacification (PCO) in vitro.

SETTING

Cell and Molecular Biology Research Laboratory, Department of Ophthalmology, Ludwig-Maximilians-University Munich, Real Eyes, Ophthalmology Center, Munich, and Institute for Clinical Pathology, Goethe University Frankfurt, Frankfurt, Germany.

DESIGN

Experimental study.

METHODS

Fifteen cadaver capsular bags were cultivated from 8 human donors under standard cell culture conditions. For preparation of the capsular bag, 4 groups were established as follows: femtosecond laser-assisted cataract surgery standard energy (n = 3), femtosecond laser-assisted cataract surgery high energy (n = 3), phacoemulsification (n = 6), and hydrodissection without energy (extracapsular cataract extraction) (n = 3). Growth of lens epithelial cells was observed and photodocumented. The days until full cell coverage of the posterior capsule were documented. Capsular bags were stained for fibronectin, α-smooth muscle actin, and collagen type 1.

RESULTS

Cell growth patterns in all treatment groups were comparable, with no statistically significant differences detected at any timepoint measured (P = .81, Kruskal-Wallis). The markers for fibrosis were equally distributed in all groups, indicating an equal fibrotic reaction in all groups.

CONCLUSION

Femtosecond laser-assisted cataract surgery did not increase different cellular responses in PCO formation comparison with phacoemulsification in vitro, even when higher laser pulse energy levels were used.