Neuroprotective Effect of Citicoline Eye Drops on Corneal Sensitivity After LASIK

The Role of Citicoline and Coenzyme Q10 in Retinal Pathology

Ocular neurodegenerative diseases such as glaucoma, diabetic retinopathy, and age-related macular degeneration are common retinal diseases responsible for most of the blindness causes in the working-age and elderly populations in developed countries. Many of the current treatments used in these pathologies fail to stop or slow the progression of the disease. Therefore, other types of treatments with neuroprotective characteristics may be necessary to allow a more satisfactory management of the disease. Citicoline and coenzyme Q10 are molecules that have neuroprotective, antioxidant, and anti-inflammatory properties, and their use could have a beneficial effect in ocular neurodegenerative pathologies. This review provides a compilation, mainly from the last 10 years, of the main studies that have been published on the use of these drugs in these neurodegenerative diseases of the retina, analyzing the usefulness of these drugs in these pathologies.

Neurostimulation for dry eye disease

PURPOSE OF REVIEW

To review the neuroanatomy and physiology of the basal and reflex tearing and present the available and developing therapies using the concept of neurostimulation in dry eye disease (DED).

RECENT FINDINGS

The most prevalent current DED treatments seek to supplement low tear volume and tear components or reduce inflammation. Neurostimulation is a unique approach gaining momentum in recent years, geared toward increasing the production of all basal tear components by stimulating the nerves responsible for producing the various tear components. The neuroanatomy of the lacrimal unit provides several possible access points to stimulate tear production through two arms of the sensory trigeminal nerves. Modes of stimulation include chemical or energy in electrical or magnetic form. Research thus far has shown that neurostimulation can achieve lacrimal, goblet cell, and meibomian gland stimulation. Subjectively it improves symptoms of DED. Clinically, neurostimulation has improved the signs and symptoms of DED by increasing basal tear production and tear volume.

SUMMARY

Neurostimulation using electrical, mechanical, or chemical means is a novel concept to increase tear production and was demonstrated to be an effective, safe, and well-tolerated method for managing DED.

Metabolomics comparison of cord and peripheral blood-derived serum eye drops for the treatment of dry eye disease

Allogeneic peripheral blood-derived (PBS) serum eye drops have been largely used in the treatment of dry eye disease (DED). Recently, cord blood has emerged as an effective alternative serum source (cord blood serum, CBS), containing a higher amount of growth factors than PBS, it holds the promise of a better capability to stimulate corneal healing. However, the lack of a standardized method for preparation, dispensation, storage and a poor biochemical characterization still hamper the establishment of a clinical consensus. Here the metabolomes of the two different serum eye drop preparations were compared using proton nuclear magnetic resonance spectroscopy. We found that both PBS and CBS contained several organic compounds, the majority of them already detected in human tears and may be thereby considered lacrimal substitutes. Metabolites having in the multivariate statistical analysis Partial least squares discriminant analysis (PLS-DA) a VIP scores > 1.0 were considered to be significantly different. All the metabolites identified were found to have a p < 0.05 in the univariate analysis. CBS, in particular, showed the highest amount of choline, myo-inositol, glutamine, creatine and β-hydroxybutyrate. These evidences constitute relevant advances towards serum eye drops characterization and confirm that cord blood is a valid alternative source of serum eye drops.

Role of Choline in Ocular Diseases

Choline is essential for maintaining the structure and function of cells in humans. Choline plays an important role in eye health and disease. It is a precursor of acetylcholine, a neurotransmitter of the parasympathetic nervous system, and it is involved in the production and secretion of tears by the lacrimal glands. It also contributes to the stability of the cells and tears on the ocular surface and is involved in retinal development and differentiation. Choline deficiency is associated with retinal hemorrhage, glaucoma, and dry eye syndrome. Choline supplementation may be effective for treating these diseases.

CORNEAL NEUROTIZATION IN A PATIENT WITH SEVERE NEUROTROPHIC KERATOPATHY. CASE REPORT

PURPOSE

Neurotrophic keratopathy (NK) is a degenerative corneal disease caused by damage to the trigeminal innervation due to a decrease in corneal sensitivity or complete anaesthesia. Impaired corneal innervation leads to morphological and metabolic disorders of the epithelium. In addition, it also leads to the development of recurrent or persistent epithelial defects in corneal ulcers, which may progress to stromal lysis and corneal perforation. One possible solution for severe NK is reinnervation of the anaesthetic cornea (corneal neurotization) using the supraorbital nerve and an autologous sensory nerve graft (indirect neurotization). This article presents the results of corneal neurotization in a young male patient with persistent epithelial defects and corneal ulcers due to corneal denervation.

RESULTS

A 22-year-old man with a history of neurosurgery for astrocytoma of the cerebellum and trunk on the right side at the age of 2 years, was observed for postoperative paresis of the right facial nerve with lagophthalmos in his childhood. The presence of asymptomatic dysfunction of the right trigeminal nerve was also noted. At the age of 22 years, after right eyeball contusion, the vision of the right eye decreased and a persistent epithelial defect developed, followed by corneal ulceration. Due to the exhaustion of therapeutic options in a young patient with corneal anaesthesia, the cornea was reinnervated via the contralateral supraorbital nerve using an autologous sural nerve graft. Five months after the surgery, the sensitivity of the cornea of the right eye began to recover. After amniotic membrane transplantation, the extensive epithelial defect healed, and the opaque corneal stroma gradually cleared up.

CONCLUSION

The reinnervation of the anaesthetic cornea (corneal neurotization) using the supraorbital nerve and the autologous sensory nerve graft represents a new solution for severe NK treatment. The severe corneal condition in our patient healed after the surgery.

The Potential Neuroprotective Role of Citicoline in Hepatic Encephalopathy

Purpose

Hepatic encephalopathy (HE) is described as impaired brain function induced by liver failure. Ammonia is the most suspected chemical involved in brain injury during HE. Although the precise mechanism of HE is not clear, several studies mentioned the role of oxidative stress in ammonia neurotoxicity. In animal models, the use of some compounds with antioxidant properties was reported to reduce the neurotoxic effects of ammonia, improve energy metabolism, and ameliorate the HE symptoms. Citicoline is a principal intermediate in the biosynthesis pathway of phosphatidylcholine that acts as neurovascular protection and repair effects. Various studies mentioned the neuroprotective and antioxidative effects of citicoline in the central nervous system. This study aims to investigate the potential protective effects of citicoline therapeutic in an animal model of HE.

Materials and Methods

Mice received acetaminophen (APAP,1g/kg, i. p.) and then treated with citicoline (500 mg/kg, i.p) one and two hours after APAP. Animals were monitored for locomotor activity and blood and brain ammonia levels. Moreover, markers of oxidative stress were assessed in the brain tissue.

Results

The result of the study revealed that plasma and brain ammonia and the liver injury markers increased, and locomotor activity impaired in the APAP-treated animals. Besides, an increase in markers of oxidative stress was evident in the brain of the APAP-treated mice. It was found that citicoline supplementation enhanced the animal’s locomotor activity and improved brain tissue markers of oxidative stress.

Conclusion

These data propose citicoline as a potential protective agent in HE. The effects of citicoline on oxidative stress markers could play a fundamental role in its neuroprotective properties during HE.

Effect of neuroprotective citicoline eye drops on macular microcirculation

BACKGROUND AND OBJECTIVE

To use optical coherence tomography (OCTA) examination of the retinal microvascular structures to evaluate the effect of neuroprotective eye drops (citicoline, OMK1^®) administered for laser in situ keratomileusis (LASIK) surgery.

PATIENTS AND METHODS

This prospective study included 45 patients treated with citicoline after LASIK and 48 patients not treated with citicoline after LASIK as a control group. In both groups, the foveal avascular zone (FAZ), retinal superficial vascular density (SVD), and deep vascular density (DVD) in the foveal and parafoveal areas were measured preoperatively and at 1 and 3 months postoperatively using OCTA.

RESULTS

No significant difference was detected between the groups in terms of preoperative SVD or DVD in the foveal and parafoveal zones and all quadrants (superior, inferior, temporal, and nasal) (P > 0.05). Similarly, no significant difference was detected between the citicoline group and control group in terms of SVD or DVD in the foveal and parafoveal zones at 1 and 3 months after LASIK (P > 0.05).

CONCLUSIONS

Despite their neuroprotective effect, topical citicoline drops had no significant effect on the superficial and deep microvascular structures of the retina or choriocapillaris.