A New Matrix Therapy Agent for Faster Corneal Healing and Less Ocular Discomfort Following Epi-off Accelerated Corneal Cross-linking in Progressive Keratoconus

Pain mechanisms and management in corneal cross-linking: a review

Though corneal collagen cross-linking (CXL) is an increasingly available and effective treatment for keratoconus, few reports have considered its impact on pain-related physiology in depth. This comprehensive narrative review summarises mechanisms underlying pain in CXL and clinical care possibilities, with the goal of future improvement in management of CXL-related pain. Postoperative pain associated with CXL is largely due to primary afferent nerve injury and, to a smaller extent, inflammation. Chronification of pain after CXL has not been reported, even as long-term nerve damage without regeneration following standard CXL treatment is frequently observed. The lack of pain chronification may be due to the minimally invasive nature of the procedure, with its rapidly recovering superficial corneal wound, and to the positive anti-inflammatory changes of the tear film that have been described after CXL. Different CXL approaches have been developed, with the transepithelial epithelial-on technique (epi-on) associated with less postsurgical pain than the gold standard, epithelial-off technique (epi-off). After the first few days, however, the difference in pain scores and need for analgesics between epi-on and epi-off disappear. Patients experience relatively high-intensity pain the first few days post-CXL, and many strategies for acute pain control following CXL have been studied. Currently, no method of pain management is considered superior or universally accepted. Acute pain following CXL is a recognised and clinically significant side effect, but few CXL studies have systematically investigated postoperative pain and its management. This review aims to improve patient pain outcomes following this increasingly common procedure.

Fast and sustained healing of resistant corneal ulcers using corneal scrubbing and matrix regenerating therapy

AIM

The aim of this study was to assess the efficacy and safety of corneal scrubbing associated with matrix regenerating agent on corneal wound healing in patients with persistent corneal ulcers.

METHODS

This was a retrospective case study in patients with difficult-to-treat corneal ulcer. Corneal scrubbing was performed with a sterile dry cotton bud to eliminate damaged epithelial cells and corneal deposits, promoting epithelial renewal. Regenerating agent was then administered as one eye drop every 2 days in addition to preservative-free ocular lubricants. A bandage contact lens was applied in case of moderate-to-severe corneal pain. Corneal ulcers were regularly assessed until healing.

RESULTS

In total, 17 patients with a chronic corneal ulcer of various etiologies for several months on average were enrolled. Corneal scrubbing combined with regenerating agent administration led to a rapid corneal ulcer size reduction from 26.4 ± 20.6 mm² after scrubbing (before regenerating agent) to 7.2 ± 7.1 mm² at day 5, 3.3 ± 6.0 mm² at day 10, and 0.9 ± 2.3 mm² at day 18. Complete corneal ulcer healing was observed in 35.2% of patients within 10 days, in 70.4% within 18 days, and in all patients within 25 days. Corneal ulcer relapse was observed in two (11.8%) patients after 6 weeks and 5 months, respectively; both were successfully treated using the same procedure. The regenerating agent was well tolerated in all patients.

CONCLUSION

In this study, combined corneal scrubbing and matrix regenerating therapy (with or without bandage contact lens) led to a rapid healing and successful resolution of persisting corneal ulcers, including large and deep corneal ulcers.

Case Reports for Topical Treatment of Corneal Ulcers with a New Matrix Therapy Agent or RGTA® in Dogs

Superficial corneal ulcers that fail to heal within a normal time period and are refractory to conventional therapy in dogs are common in veterinary practice. Different etiologies can lead to this result, including spontaneous chronic corneal epithelial defects (SCCEDs) and ulcerative keratitis associated with bullous keratopathy. Thus, there is an urgent need to find new therapeutic approaches such as matrix therapy replacement. To determine the efficacy of a new ophthalmic treatment (Clerapliq^®) for SCCEDs and ulcerative keratitis associated with bullous keratopathy, a total of 11 dogs referred to the clinic because of nonhealing erosive ulcers after a classic primary treatment were enrolled to get this new treatment. Dogs underwent ophthalmic exams and 7 dogs (10 eyes) were diagnosed with superficial ulceration and 4 dogs (5 eyes) with bullous keratopathy due to endothelial dystrophy/degeneration. They received eye drops of Clerapliq^® every 3 days until recovery. The results showed that the corneas with recurrences of the ulcers were resolved predominantly by using Clerapliq^® every 3 days in 83.3% of the cases during a period of treatment ranging between 6 to 35 days. Therefore, this new approach using matrix therapy regenerating technology in treating superficial ulcers and bullous keratopathy in dogs can be successfully considered as an adjunctive therapy.

Corneal Repair and Regeneration: Current Concepts and Future Directions

The cornea is a unique tissue and the most powerful focusing element of the eye, known as a window to the eye. Infectious or non-infectious diseases might cause severe visual impairments that need medical intervention to restore patients' vision. The most prominent characteristics of the cornea are its mechanical strength and transparency, which are indeed the most important criteria considerations when reconstructing the injured cornea. Corneal strength comes from about 200 collagen lamellae which criss-cross the cornea in different directions and comprise nearly 90% of the thickness of the cornea. Regarding corneal transparency, the specific characteristics of the cornea include its immune and angiogenic privilege besides its limbus zone. On the other hand, angiogenic privilege involves several active cascades in which anti-angiogenic factors are produced to compensate for the enhanced production of proangiogenic factors after wound healing. Limbus of the cornea forms a border between the corneal and conjunctival epithelium, and its limbal stem cells (LSCs) are essential in maintenance and repair of the adult cornea through its support of corneal epithelial tissue repair and regeneration. As a result, the main factors which threaten the corneal clarity are inflammatory reactions, neovascularization, and limbal deficiency. In fact, the influx of inflammatory cells causes scar formation and destruction of the limbus zone. Current studies about wound healing treatment focus on corneal characteristics such as the immune response, angiogenesis, and cell signaling. In this review, studied topics related to wound healing and new approaches in cornea regeneration, which are mostly related to the criteria mentioned above, will be discussed.

Evaluation of corneal epithelial wound healing after penetrating keratoplasty in patients receiving a new matrix therapy agent (regenerating agent)

OBJECTIVES

Complete epithelial wound healing is a milestone in early postoperative care after penetrating keratoplasty. The re-epithelialization rate after penetrating keratoplasty was measured in patients receiving a new matrix therapy agent (regenerating agent, Cacicol^®) that mimics heparan sulphates.

METHODS

This was a prospective, open-label, uncontrolled, single-centre observational study. A total of 33 consecutive patients (33 eyes) who underwent an 8.25-mm diameter penetrating keratoplasty were treated with regenerating agent eye drops: one drop in the operating theatre immediately after graft, then on alternate days. Patients were divided into those at low risk (13 patients) and high risk (20 patients) of delayed wound healing, and follow-up was performed by digital slit lamp with fluorescein-dye testing repeated daily at a fixed time. Dye area was measured using ImageJ freeware. The main endpoint was epithelial healing after regenerating agent therapy.

RESULTS

The mean ± standard deviation time to complete healing for all patients was 2.7 ± 1.1 (median: 3, range: 1-6) days. This was obtained on Day 1 for 15% of patients, Day 2 for 33%, Day 3 for 88%, Day 4 for 94% and Day 6 for 100%. There was no significant difference between low- and high-risk patients. The area of epithelial defect decreased by a mean ± standard deviation of 75% ± 22% between Day 1 and Day 2, corresponding to a mean ± standard deviation wound-healing rate of 11.5 ± 6.5 mm²/D. There were no systemic or local side effects related to regenerating agent.

CONCLUSION

These preliminary data suggest that regenerating agent could be a useful, non-invasive therapeutic approach in postoperative management of penetrating keratoplasty with the potential to accelerate re-epithelialization.

Application of Novel Drugs for Corneal Cell Regeneration

Corneal transplantation has been the only treatment method for corneal blindness, which is the major cause of reversible blindness. However, despite the advancement of surgical techniques for corneal transplantation, demand for the surgery can never be met due to a global shortage of donor cornea. The development of bioengineering and pharmaceutical technology provided us with novel drugs and biomaterials that can be used for innovative treatment methods for corneal diseases. In this review, the authors will discuss the efficacy and safety of pharmacologic therapies, such as Rho-kinase (ROCK) inhibitors, blood-derived products, growth factors, and regenerating agent on corneal cell regeneration. The promising results of these agents suggest that these can be viable options for corneal reconstruction and visual rehabilitation.

RGTA® or ReGeneraTing Agents mimic heparan sulfate in regenerative medicine: from concept to curing patients

The importance of extracellular matrix (ECM) integrity in maintaining normal tissue function is highlighted by numerous pathologies and situations of acute and chronic injury associated with dysregulation or destruction of ECM components. Heparan sulfate (HS) is a key component of the ECM, where it fulfils important functions associated with tissue homeostasis. Its degradation following tissue injury disrupts this delicate equilibrium and may impair the wound healing process. ReGeneraTing Agents (RGTA^®s) are polysaccharides specifically designed to replace degraded HS in injured tissues. The unique properties of RGTA^® (resistance to degradation, binding and protection of ECM structural and signaling proteins, like HS) permit the reconstruction of the ECM, restoring both structural and biochemical functions to this essential substrate, and facilitating the processes of tissue repair and regeneration. Here, we review 25 years of research surrounding this HS mimic, supporting the mode of action, pre-clinical studies and therapeutic efficacy of RGTA^® in the clinic, and discuss the potential of RGTA^® in new branches of regenerative medicine.