The Healing Power of Hydrogels for Uveitis

(Posted on Sunday, December 10, 2023)

This article was published on Forbes on 12/4/2023.

This story is part of a series on the current progression in Regenerative Medicine. This piece is part of a series dedicated to the eye and improvements in restoring vision. 

In 1999, I defined regenerative medicine as the collection of interventions that restore tissues and organs damaged by disease, injured by trauma, or worn by time to normal function. I include a full spectrum of chemical, gene, and protein-based medicines, cell-based therapies, and biomechanical interventions that achieve that goal.

Uveitis is a type of eye inflammation that affects the middle layer of tissue in the eye wall called the uvea. This disorder can occur suddenly, and symptoms may worsen quickly, affecting one or both eyes. The signs and symptoms of uveitis can include eye redness, pain, light sensitivity, blurred vision, floaters, and decreased vision. 

Approximately half of all cases of uveitis are of unknown origin. In contrast, the other half may be related to autoimmune or inflammatory disorders such as systemic lupus erythematosus, sarcoidosis, or Crohn’s disease.

Categories of Uveitis

Uveitis is a complex medical condition that causes inflammation in different eye parts, leading to a wide range of symptoms that can significantly impair vision and quality of life. There are four main categories of uveitis, each with unique signs and complications.

The most common type of uveitis is anterior uveitis, which affects the iris and ciliary body at the front of the eye. This type of uveitis, also known as iritis, is characterized by eye pain, redness, sensitivity to light, and blurred vision. Sometimes, the pupil may become smaller and irregular, leading to vision problems.

Intermediate uveitis affects the vitreous and the retina at the back of the eye, and it’s often associated with systemic diseases such as sarcoidosis or multiple sclerosis. This uveitis can cause floaters, blurred vision, and difficulty seeing in low-light conditions. It can lead to retinal detachment and permanent vision loss in severe cases.

Posterior uveitis affects the choroid, retina, and optic nerve at the back of the eye, and it’s often caused by infections or autoimmune diseases such as toxoplasmosis, herpes, or Behcet’s disease. This type of uveitis can cause a gradual loss of vision, floaters, and sensitivity to light. In some cases, it can also lead to macular edema, scarring, or retinal detachment.

Finally, panuveitis affects all parts of the uvea, from the front to the back of the eye. This type of uveitis is often the most severe and can cause a wide range of symptoms, including pain, redness, blurred vision, floaters, and photophobia. Panuveitis is often associated with systemic autoimmune diseases such as lupus, rheumatoid arthritis, or sarcoidosis, and it can lead to severe complications such as glaucoma, cataracts, or retinal detachment.

Treatments of Uveitis

As uveitis can cause severe complications that lead to permanent vision loss, early diagnosis and treatment are essential. Therapy aims to treat the inflammation and check the eyes regularly to prevent further damage and vision loss. Ophthalmologists typically prescribe eye-drop medications that reduce inflammation and dilate the pupil. In some cases, injections or pills may also be necessary. While these treatments can effectively control symptoms, they do not always relieve severe cases adequately.

Exploring Hydrogels for Uveitis

Several hydrogel formulations have been researched for their potential use in treating uveitis because of their unique biodegradability properties, biocompatibility, and ability to sustain drug release. Hydrogels are polymeric materials that absorb and retain water, making them an ideal carrier for therapeutic agents. Moreover, these hydrogels can also provide sustained release of therapeutic agents, resulting in longer-lasting treatment effects and a reduced need for frequent dosing.

A recent study published in the Journal of Materials Chemistry B investigated the potential of using an injectable, thermo-sensitive, and biodegradable in situ hydrogel to deliver indomethacin to treat uveitis. The hydrogel exhibited good biocompatibility and sustained release of indomethacin for over two weeks. However, the study was limited to in vitro testing and only evaluated the hydrogel’s ability to release indomethacin over two weeks. The study did not examine the hydrogel’s impact on other ocular tissues or the eye as a whole. Therefore, further research is needed to determine any potential side effects before it can be used as a treatment option for uveitis.

Researchers from Nantong University also recently studied using hydrogels made from γ-cyclodextrin for treating anterior uveitis by delivering flurbiprofen to the eyes. The study found that the hydrogels improved the anti-inflammatory effects of flurbiprofen when given to rabbits. Still, it is essential to note that the study only tested on rabbits, and the length of the study did not allow for long-term effects to be evaluated.

Preparation of γ-cyclodextrin-based polypseudorotaxane hydrogels and topical delivery of FLB for treating anterior uveitis.

Multifunctional Hydrogel Eye Drops 

Multifunctional hydrogel eye drops have also been investigated for treating uveitis through synergistic therapy mechanisms. Synergistic therapy mechanisms refer to the combined effects of multiple therapeutic agents that work together in a complementary fashion to enhance the overall therapeutic outcome. Simply put, it is the idea that two or more medications or substances can work together to produce a more significant effect than what would be possible if they were used alone. 

A recent study in The American Chemical Society’s Nano Journal has shown that hydrogel eye drops with multiple functions can effectively alleviate uveitis. To test the hydrogel eye drops, researchers induced uveitis in mice and administered the drops. The results showed that the eye drops significantly reduced inflammation and prevented the formation of cataracts. The hydrogel eye drops achieved this by slowly releasing therapeutic agents, which provided long-lasting relief to the eyes. Additionally, the eye drops targeted only the inflamed areas of the eye, reducing the risk of side effects that can happen with other treatments. 

However, it is essential to note that the study was conducted on animals and still needs to be determined if the hydrogel eye drops will also work in humans. More research is necessary to confirm their safety and effectiveness for human use.

Tackling Uveitis 

Uveitis is a serious condition that can lead to permanent vision loss if left untreated. Although current medications can help manage the symptoms, they often offer only limited relief and have potential side effects. Hydrogels, on the other hand, have the potential to provide sustained and controlled release of drugs and can be a promising alternative to traditional treatments for uveitis. With more research and studies, hydrogel-based drug delivery systems may offer safer and more effective solutions for managing uveitis.

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