Cellular and molecular assessment of rose bengal photodynamic antimicrobial therapy on keratocytes, corneal endothelium and limbal stem cell niche.

Rose Bengal Photodynamic Antimicrobial Therapy (RB-PDAT) is a novel potential treatment for progressive infectious keratitis. The principle behind this therapy is using Rose Bengal as a photosensitizer that can be activated by green light and results in the production of oxygen free radicals which in turn eradicate the microorganism. Given RB-PDAT's mechanism of action and the potential cytotoxic effects, concerns regarding the safety of this technique have arisen. The purpose of this study was to evaluate the effect of RB-PDAT on keratocytes, while focusing on the safety profile that the photo-chemical reaction has on the limbal stem cell (LSC) niche and endothelial cell layer of the treated cornea. To perform RB-PDAT, Rose Bengal solution (0.1% RB in BSS) was applied to the right cornea of rabbits for 30 min and then irradiated by a custom-made green LED light source (525 nm, 6 mW/cm2) for 15 min (5.4 J/cm2). Three rabbits were sacrificed and enucleated after 24 h for evaluation. TUNEL assay and immunohistochemistry for endothelium and limbal stem cell viability were performed on whole mounts and frozen sections in treated and control eyes. LSC of both eyes were isolated and cultured to perform MTT viability and proliferation, and scratch wound healing assays under time-lapse microscopy. Interestingly, while Rose Bengal dye penetration was superficial, yet associated cellular apoptosis was evidenced in up to 1/3 of the stromal thickness on frozen sections. TUNEL assay on whole mounts showed no endothelial cell death following treatment. Immunohistochemistry on frozen sections of LSC displayed no structural difference between treated and non-treated eyes. There was no difference in LSC proliferation rates and scratch wound healing assay demonstrated adequate cell migration from treated and non-treated eyes. The current study suggests that even though penetration of the RB dye has been shown to be limited, oxidative stress produced by RB-PDAT can reach deeper into the corneal stroma. Nevertheless, our results show that performing RB-PDAT is safe on the corneal endothelium and has no effect on LSC viability or function.

Salzmann's nodular degeneration of cornea associated with thyroid eye disease.

Salzmann's nodular degeneration (SND) typically occurs in patients who are female, 50-60 years old, and have a history of corneal inflammation and irritation. Multiple case reports have documented associations between SND and trachoma, viral infections, trauma, contact lens wear, corneal surgeries and corneal exposure. The authors describe a patient with bilateral SND confirmed by anterior segment optical coherence tomography (OCT) imaging in the context of thyroid eye disease (TED) and history of LASIK. Treatment involved propylthiouracil (PTU), artificial tear use, loteprednol etabonate ophthalmic gel, eyelid taping and selenium supplementation and prospective superficial keratectomy with diamond burr polish.

Successful simple limbal epithelial transplantation (SLET) in lime injury-induced limbal stem cell deficiency with ocular surface granuloma.

A 9-year-old boy presented with unilateral, total limbal stem cell deficiency (LSCD) complicated by the presence of a large fibro-vascular ocular surface mass lesion secondary to accidental lime injury. The pathological tissue covering the cornea was excised and simple limbal epithelial transplantation (SLET) was performed using autologous limbal tissue from the fellow eye. Histopathology of the excised ocular surface tissue revealed exuberant granulation tissue interspersed with retained calcium particles. At 6 weeks postoperatively, a focal recurrence of LSCD with symblepharon and forniceal shortening was noted superiorly. This was successfully managed by performing conjunctival autografting along with supplemental SLET. The unaided vision had improved from light perception at presentation to 20/40 at 6 months postoperatively. The fornices were deep and the corneal surface was avascular, epithelised and stable. This case demonstrates the efficacy of SLET in a child with severe ocular burns, highlighting the role of supplementary procedures customised to treat focal recurrences of LSCD.

Yellow corneal ring associated with vitamin supplementation for age-related macular degeneration.

PURPOSE: To report the first described cases of peripheral yellow corneal rings secondary to vitamin supplementation for age-related macular degeneration (ARMD). DESIGN: Retrospective single-center case series. PARTICIPANTS: The eyes of 4 patients taking vitamin supplementation for ARMD were examined at the University of Pittsburgh Medical Center Department of Ophthalmology between January 2010 and April 2011. METHODS: We reviewed the medical records of 4 patients with peripheral corneal rings receiving vitamin supplementation for ARMD. MAIN OUTCOME MEASURES: The presence of peripheral yellow corneal rings, skin findings, and serum carotene levels. RESULTS: Each patient had circumferential, yellow, peripheral corneal rings and exhibited subtle yellowing of the skin most notable on the palms. Serum carotene levels were normal in 2 of the 3 patients and markedly elevated in the last patient in whom it was measured. CONCLUSIONS: It is unclear at this time how to counsel patients with this ocular finding. We suspect that these rings are more common than generally appreciated because they may have a subtle appearance or be misdiagnosed as arcus senilis. We suggest that a formal study be performed on a cohort of patients taking vitamin supplementation for macular degeneration that specifically screens for yellow rings and measures serum carotene levels when they are identified.

[Limbal stem cell deficiency following multiple intravitreal injections]. / Insuficiencia limbar secundaria a múltiples inyecciones intravítreas.

CASE REPORT: A 68 year-old male with idiopathic choroidal polypoidal vasculopathy received seven intravitreal injections of bevacizumab in the supero-nasal quadrant. He later developed a localized limbal stem cell deficiency which required limbal transplantation from the same eye. Two months after surgery, a slight improvement of visual acuity was noted, along with an intact ocular surface, clear cornea and decreased inflammation. DISCUSSION: Repeated surgical trauma on the limbus and surrounding areas may damage the limbal stem cells, giving rise to a corneal epitheliopathy due to iatrogenic limbal deficiency. Repeated intravitreal injections may be considered as one of the possible causes.

[Pepper spray injuries of the anterior segment of the eye]. / Pfeffersprayverletzungen des vorderen Augensegmentes.

BACKGROUND: A wide variety of pepper sprays is currently available and gaining increasing popularity among both professional guardians and amateurs. Adverse side effects to the anterior segment of the eye are known but underestimated. HISTORY AND SIGNS: We present two cases with severe corneal and conjunctival damage after accidental self injury by a pepper spray (Jet Protector Guardian Angel), benzyl alcohol 90.1 %, capsaicinoids 2.6 %). THERAPY AND OUTCOME: Despite immediate and intensive irrigation, a complete epithelial defect, extensive ischemia to the limbus and the conjunctiva and a circular conjunctival chemosis were diagnosed. After slow re-epithelialization in both cases, a neurotrophic superficial keratitis, a reduced corneal sensibility and in one case deep stromal scarring were noted. CONCLUSIONS: Pepper spray application to the eye might result in severe and permanent damage to the corneo-conjunctival tissue which is not adequately addressed in the current literature. From the present case reports arise the discussion whether the irritative and lipophilic capsacin/benzyl alcohol mixture or the pyrotechnical additives nitrocellulose und sinoxide are responsible for the anterior segment injuries.