[Temperature changes of the cornea by applying an eye bandage]

COVID-19 Ocular Prophylaxis: The Potential Role of Ozonated-Oils in Liposome Eyedrop Gel

Purpose

To assess whether ozonated-oil in liposome eyedrop gel (OED) could be used to prevent the severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) infection in an in vitro infection model.

Methods

First, we tested the efficacy of OED on in vitro cell regeneration and dry eye resolution in human corneal epithelial cells (hCE-2). Second, we assessed the in vitro anti-SARS-CoV-2 infection efficacy of OED using Vero E6 cells. Tissues were examined to assess different parameters: morphology, histology, and mRNA expression at 24 hours after treatment.

Results

OED could restore 50% of the scratch in the monolayer of hCE-2 cells in vitro compared with the 25% obtained with phosphate-buffered saline solution (PBS). At 24 hours after treatment with OED, the number of microvilli and the mucin network were restored, as observed using scanning electron microscopy. In Vero E6 cells infected with a primary SARS-CoV-2 strain and treated with OED two times/day, viral replication was found to be inhibited, with a 70-fold reduction observed at 72 hours after infection compared with that under the untreated and PBS-treated conditions.

Conclusions

SARS-CoV-2 transmission through the ocular surface should not be ignored. Although the prevalence of coronavirus disease 2019 conjunctivitis infection is low, the need for a barrier to prevent possible viral infection is warranted. OED treatment may prevent the risk of SARS-CoV-2 infection after 72 hours of twice-daily applications.

Translational Relevance

Dry eye condition might be a risk factor for SARS-CoV-2 infection and OED treatment may have a preventive role.

[Ocular burns]

Ocular or thermal burns account for 7.7%-18% of ocular trauma. The majority of victims are young. The burns occur in the setting of accidents at work or in the home, or during a physical attack. Chemical burns by strong acids or bases are responsible for the most serious injuries. Associated with the destruction of limbal stem cells, they present as recurrent epithelial ulcerations, chronic stromal ulcers, deep stromal revascularization, conjunctival overlap, or even corneal perforation. The initial clinical exam is sometimes difficult to perform in the presence of burning symptoms. Nevertheless, it enables the physician to classify the injury, establish a prognosis, and most importantly, guide the therapeutic management. The Roper-Hall modification of the Hughes classification system is the most widely utilized, broken down into stages based on the size of the stromal opacity and the extent of possible limbal ischemia. This classification is now favorably supplemented by those proposed by Dua and Wagoner, which are based on the extent of the limbal stem cell deficiency. The prognosis of the more serious forms of ocular burns has markedly improved over the last decade because of a better understanding of the physiology of the corneal epithelium. Surgical techniques aimed at restoring the destroyed limbal stem cells have altered the prognosis of severe corneal burns. In order to decrease the incidence of burns, prevention, particularly in industry, is essential.

Modelling the impact of blood flow on the temperature distribution in the human eye and the orbit: fixed heat transfer coefficients versus the Pennes bioheat model versus discrete blood vessels

Prediction of the temperature distribution in the eye depends on how the impact of the blood flow is taken into account. Three methods will be compared: a simplified eye anatomy that applies a single heat transfer coefficient to describe all heat transport mechanisms between the sclera and the body core, a detailed eye anatomy in which the blood flow is accounted for either by the bioheat approach, or by including the discrete vasculature in the eye and the orbit. The comparison is done both for rabbit and human anatomies, normo-thermally and when exposed to homogeneous power densities. The first simplified model predicts much higher temperatures than the latter two. It was shown that the eye is very hard to heat when taking physiological perfusion correctly into account. It was concluded that the heat transfer coefficient describing the heat transport from the sclera to the body core reported in the literature for the first simplified model is too low. The bioheat approach is appropriate for a first-order approximation of the temperature distribution in the eye when exposed to a homogeneous power density, but the discrete vasculature down to 0.2 mm in diameter needs to be taken into account when the heterogeneity of the temperature distribution at a mm scale is of interest.

Emergency treatment of eye burns: which rinsing solution should we choose?

BACKGROUND

In the treatment of eye burns few data on the comparative application of rinsing solutions exist. We present experiments in vitro and ex vivo on the pH changes that can be achieved in alkali eye burns with currently distributed and propagated rinsing fluids like water, saline solution, Cederroth Eye Wash Solution (including borate buffer), Diphoterine, Ringers lactate solution and phosphate buffer.

METHODS

Titration curves in beakers are compared with ex vivo experiments on isolated rabbit eyes. We exposed eyes to burns from filter paper soaked in 2 mol NaOH, continuously measuring the anterior chamber pH by means of a micro pH electrode placed near the endothelium. In each experiment--repeated five times--the corneal burn of 20 s in 2 mol NaOH was followed by a period of 15 min of rinsing under a defined flow of 66 ml/min.

RESULTS

We found highly significant differences in intracameral pH related to different types of rinsing solutions. The return of the intracameral pH to normal was not achieved by any of the rinsing fluids, but the best results were noted for of Cederroth Eye Wash Solution (Cederroth Industrial Products, Upplands Väasby, Sweden) and the Diphoterine- and Previn solutions (Prevor, Cologne, Germany). Water played an intermediate role whereas saline and phosphate buffer were not efficient at lowering intracameral pH after alkali burns.

CONCLUSION

In alkali burns we recommend efficient buffering solutions. The tested isotonic phosphate buffer (PBS) was not effective at buffering the intraocular pH. Water was found to be much less efficient than Previn, Diphoterine or Cederroth Eye Wash solution in balancing intraocular pH.

[The influence of transport on organ cultured corneas. An experimental study of porcine corneal endothelium]

BACKGROUND

To investigate the influence of transport on the quality of corneas in organ culture, based on the vitality of the corneal endothelium.

METHODS

Transport was simulated for 222 porcine corneal disks. These were placed in standard transportation containers filled with organ culture medium II, kept in an incubator and then shaken on a laboratory shaker.

RESULTS

Agitated corneas at all acceleration rates always showed less endothelial cell damage than corneas kept motionless. The best condition was found after maximum accelerations of 0.10 g and 0.72 g. Damage consisted predominantly of disseminated cell loss and circular cell damage. A storage temperature of 37 degrees C caused most harm to the endothelium.

CONCLUSION

The reduction in endothelial damage found in corneas after agitation can be attributed to a better distribution of nutrients in the transportation container. Assuming transferability, a better quality of human grafts can be achieved by inducing slight motions of corneas in organ culture.

Emergency treatment of chemical and thermal eye burns

Chemical and thermal eye burns account for a small but significant fraction of ocular trauma. The speed at which initial irrigation of the eye begins, has the greatest influence on the prognosis and outcome of eye burns. Water is commonly recommended as an irrigation fluid. However, water is hypotonic to the corneal stroma. The osmolarity gradient causes an increased water influx into the cornea and the invasion of the corrosive substance into deeper corneal structures. We therefore recommend higher osmolarities for the initial rinsing to mobilize water and the dissolved corrosives out of the burnt tissue. Universal systems such as amphoteric solutions, which have an unspecific binding with bases and acids, provide a convenient solution for emergency neutralisation. Both conservative anti-inflammatory therapy and early surgical intervention are important to reduce the inflammatory response of the burnt tissue. In most severe eye burns, tenonplasty re-establishes the conjunctival surface and limbal vascularity and prevents anterior segment necrosis.

Eye burns: an emergency and continuing problem

Adequate treatment of eye burns is an essential task of rescue teams. Clinical and occupational medicine studies have shown that efficient emergency treatment can prevent severe eye damage, but therapy is frequently delayed or inadequate. When initial therapy has been delayed or missed, several treatment strategies, including surgery, are available that may improve the outcome of an injury with poor visual prognosis. Discussed in this review are common accident mechanisms, causative agents and biophysical/pathogenetic aspects of eye burns, together with emergency and long-term treatment strategies including surgical procedures, and factors influencing outcome.