ESR 5, Nadia Toffoletto, discusses how intraocular lenses have the capacity to reduce the need for eye drops after cataract surgery, and change how the industry looks at post-operative care and treatment options for patients.
My grandmother Lidia received brand new intraocular lenses (IOLs) a few years ago, as a treatment for cataract. Right after surgery, she was very surprised on how she could immediately resolve her blurred vision, with a minimally invasive implant and a fast recovery. In the following weeks, however, I remember seeing her struggling with three different types of eye drops, each to be administered every few hours, with half of the drops falling outside her eye and half forgotten while she was busy in her everyday activities.
The numbers say she is not the only one: it was estimated that cataract surgery patients only apply half of the prescribed number of drops and it is very frequent to observe patients interrupting the treatment before completion.
Cataract surgery is the standard of care for severe cataractous eyes. The procedure consists in the removal of the damaged lens and the subsequent implant of an IOL made of polymeric material. Despite the advances in the technique and the evolution in the different types of IOLs made this procedure one of the most cost-effective in the current healthcare, some post-operative complications (such as inflammation and infection) can still occur and cause discomfort and visual impairment to the patient, as well as a prolonged recovery time. For this reason, the current prophylaxis after cataract surgery consists in the administration of antibiotics and anti-inflammatory drugs in the form of eye drops for 2-4 weeks after surgery.
In the last decade, many researchers focused on the possibility of directly using the implanted IOLs as a drug delivery platform, to overcome the issues related to patient compliance but also to increase the effectiveness of the pharmacological treatment. Eye drops, in fact, are subjected to the poor drug permeability through the cornea and it is estimated that at most 5% of the drugs can reach the interior part of the eye.
We focused our work on the design of materials suitable for IOLs able to deliver simultaneously a NSAID (bromfenac sodium) and a corticosteroid (dexamethasone sodium) for the prevention of chronic inflammation after cataract surgery, which could lead to macular edema and, in the most serious cases, to vision loss. Our strategy was the use of functional monomers in the polymeric network of the lens. Monomers are the building blocks of polymers, and their selection influences the macro and microscopic characteristics of the material. By use of molecular simulations, we selected monomers with a high affinity to the drugs, so that the IOL material could load drugs into its structure and then release it after implant. Drug release was expected to provide therapeutic amounts of bromfenac sodium and dexamethasone sodium in the aqueous humor for about 2 and 8 weeks, respectively, which is compatible with the current eye drops prophylaxis after cataract surgery.
Drug-loaded IOLs are not present on the market yet. However, the results obtained in 10+ years of research on the topic in laboratories all over the world push to be applied to extended in vivo test and clinical trials, with the hope of reaching the objective of their use in cataract surgery in the near future and obtain a more patient-friendly and effective prevention of post-operative issues associated with the procedure.
Find out more on the current options for drug delivery from ophthalmic lenses here: https://www.mdpi.com/1999-4923/13/1/36/htm
More details on our work here: https://www.mdpi.com/1999-4923/13/7/976/htm