Role of anterior segment optical coherence tomography angiography in the assessment of acute chemical ocular injury: a pilot animal model study

To examine the use of anterior segment-optical coherence tomography angiography (AS-OCTA) in the assessment of limbal ischemia in an animal model chemical ocular injury. We conducted a prospective study using an established chemical ocular injury model in 6 rabbits (12 eyes), dividing the cornea limbus into 4 quadrants. Chemical injury grade was induced based on extent of limbal injury (0 to 360 degrees) and all eyes underwent serial slit-lamp with AS-OCTA imaging up to one month. Main outcome measure was changes in AS-OCTA vessel density (VD) comparing injured and control cornea limbal quadrants within 24 h and at one month. AS-OCTA was able to detect differences in limbal VD reduction comparing injured (3.3 ± 2.4%) and control quadrants (7.6 ± 2.3%; p < 0.001) within 24 h of ocular chemical injury. We also observed that AS-OCTA VD reduction was highly correlated with the number of quadrants injured (r = − 0.89; p < 0.001; 95% CI − 5.65 to − 1.87). Corneal vascularization was detected by AS-OCTA in injured compared to control quadrants (10.1 ± 4.3% vs 7.0 ± 1.2%; p = 0.025) at 1 month. Our animal pilot study suggests that AS-OCTA was able to detect limbal vessel disruption from various severities of acute chemical insult, and in the future, could potentially serve as an adjunct in providing objective grading of acute ocular chemical injury once validated in a clinical trial.

Opposing roles of blood-borne monocytes and tissue-resident macrophages in limbal stem cell damage after ocular injury

Limbal stem cell (LSC) deficiency is a frequent and severe complication after chemical injury to the eye. Previous studies have assumed that this is mediated by direct chemical injury. Here we show that LSC loss can occur even without direct chemical injury to LSCs. Elevation of anterior chamber (AC) pH causes acute uveal stress, release of inflammatory cytokines at the basal limbal tissue, and subsequent LSC death. In particular, peripherally-derived CCR2+ CX3CR1- monocytes cause upregulation of tumor necrosis factor alpha (TNF-α) at the limbus, causing LSC loss. In contrast to peripherally-derived monocytes, CX3CR1+ CCR2- tissue-resident macrophages are protective. Pharmacological depletion of tissue-resident macrophages prior to injury exacerbates LSC loss and increases LSC vulnerability to apoptosis following exposure to TNF-α, despite reduced CCR2+ cell infiltration into the tissue. Consistently, repopulation of the cornea by new tissue-resident macrophages after depletion reverse LSC susceptibility to inflammatory cell death. This findings have important implication in LSC protection after chemical injury.

Chemical injury induced by the use of topical imiquimod: case report

Chemical injury consists in damage caused by a substance when it comes into contact with living tissue. Certain drugs can cause this type of lesion in the oral mucosa. Imiquimod (INN) is an example. Erythema, edema, vesicles, erosions, ulcerations and inflammatory reactions are among the adverse effects associated with the use of INN. Nevertheless, since its effects disappear when terminating treatment, INN is still considered an essential drug in the treatment of condyloma acuminata, actinic cheilitis, superficial basal cell carcinoma and molluscum contagiosum. The objective of this work is to report a clinical case of a 34-year-old male patient presenting a symptomatic lesion on the lower and upper lip mucosa; while including a literature review on potential adverse effects when prescribing topical INN 5% for the oral mucosa.

Extracellular Matrix Deposition and Remodeling after Corneal Alkali Burn in Mice

Corneal transparency relies on the precise arrangement and orientation of collagen fibrils, made of mostly Type I and V collagen fibrils and proteoglycans (PGs). PGs are essential for correct collagen fibrillogenesis and maintaining corneal homeostasis. We investigated the spatial and temporal distribution of glycosaminoglycans (GAGs) and PGs after a chemical injury. The chemical composition of chondroitin sulfate (CS)/dermatan sulfate (DS) and heparan sulfate (HS) were characterized in mouse corneas 5 and 14 days after alkali burn (AB), and compared to uninjured corneas. The expression profile and corneal distribution of CS/DSPGs and keratan sulfate (KS) PGs were also analyzed. We found a significant overall increase in CS after AB, with an increase in sulfated forms of CS and a decrease in lesser sulfated forms of CS. Expression of the CSPGs biglycan and versican was increased after AB, while decorin expression was decreased. We also found an increase in KS expression 14 days after AB, with an increase in lumican and mimecan expression, and a decrease in keratocan expression. No significant changes in HS composition were noted after AB. Taken together, our study reveals significant changes in the composition of the extracellular matrix following a corneal chemical injury.

Surgical Success Evaluation in Limbal Stem Cell Deficiency Due to Chemical Injury – How to Be Accurate?

Purpose: To evaluate limbal stem cell transplantation (LSCT) success in limbal stem cell deficiency (LSCD) due to chemical injury in a tertiary eye care center in Turkey by using ‘Limbal Stem Cell Working Group’ LSCD grading system.Methods: Medical records of 80 eyes of 80 patients who underwent LSCT for LSCD secondary to chemical injury were included. The patients were divided into 3 groups according to performed surgery as limbal autograft, limbal allograft, cultivated limbal epithelial cell transplantation (CLET). Surgical success was defined as improvement in the post-operative 1st year LSCD stage.Results: The mean age of the patients was 37.9±15.7(4-71) with a Male/Female ratio of 2.4. Forty-five(56.3%) patients were injured with alkaline and 16(20%) were injured with acid substance. The mean follow-up time was 60.3±30.6(6-118.6) months. Limbal autograft, allograft and CLET were performed in 58(72.5%), 12(15%) and 10(12.5%) eyes, respectively. The interval between injury and surgery in limbal autograft, limbal allograft and CLET were 43.3±94.1(0.5-592); 14.5±10.6(2.4-32.5) and 122.8±158.9(21.1-504) months, respectively (p=0.02). The overall surgical success rate was 65%. Surgical success rates in each groups were 65.5%, 41.7% and 90%, respectively (p=0.03).Conclusion: It is vital to accurately determine the stage of the LSCD in order to evaluate the surgical success rates. Surgery type and a longer time interval between the chemical injury and surgery seems to be the most important factors associated with a higher surgical success rate. Despite the limited subject number for subgroups, the results were remarkable to emphasize the significance of the novel LSCD grading system.