Novel Photodynamic/Photothermal Treatment of Fungal Keratitis Using Rose Bengal-Loaded Polypyrrole-Gold Nanoparticles in Wistar Albino Rats.

Purpose: Fungal keratitis is a potential corneal contagious disease mainly caused by yeast such as Candida albicans and filamentous fungi such as Aspergillus niger. The response of fungal keratitis to standard antifungals is limited by the poor bioavailability, the limited ocular penetration of antifungal drugs, and the development of microbial resistance. Photodynamic therapy using rose bengal (RB) as a photosensitizer was found to be effective in fungal keratitis management; however, the hydrophilicity of RB limits its corneal penetration. Polypyrrole-coated gold nanoparticles (AuPpy NP) were introduced as a nano-delivery system of RB with high loading capacity. It was proved that (RB-AuPpy NP) exhibited a combined photodynamic/photothermal effect. This study aims to use the combined photodynamic/photothermal effect of RB-AuPpy NP as a novel protocol for treating Fungal Keratitis in albino Wistar rats. Methods: The rats were infected by C. albicans and A. niger. Each infected group of rats was subdivided into groups treated by RB followed by radiation (photodynamic only), AuPpy NP followed by radiation (photothermal only), and RB-AuPpy NP followed by radiation (combined photodynamic/photothermal). Histopathological examination and slit lamp imaging were done to investigate the results. Results: The results revealed that 3 weeks post-treatment, the corneas treated by RB-AuPpy NP (combined photodynamic/photothermal effect) exhibited the best improvement compared to other groups. Conclusion: This protocol can be considered a promising one for Fungal Keratitis management that overcomes microbial resistance problems.

Investigating the light emitting diode (LED) flashlight characteristics of a sample of smartphones for its safety in indirect retinal photography.

Introduction: the off-label use of smartphones for indirect retinal photography and videography made it a popular ophthalmic clinical practice for its ubiquity and simplicity which enhanced telemedical care. Smartphone indirect retinal photography involves focusing the bright flashlight from the light emitting diode (LED) source on the rear side of the phone on the patient´s retina. Phototoxic hazards of the bright light on the already compromised patients´ retina raise concerns that require safety studies. The aim of this work is to study the characteristics of LED flashlights of a sample of smartphone types currently in use by ophthalmologists in Egypt to evaluate for potential photobiological implications when used in conjunction with + 20-diopter indirect ophthalmoscopy condensing lens for indirect photography of the retina. Methods: the spectral profile, weighted irradiance, and thermal exposure rates produced by a variety of smartphones´ LED flashlights currently used by ophthalmology specialists and trainees at the Comprehensive Outpatient Clinic of the Research Institute of Ophthalmology, Giza, Egypt, were tested in this study when collimated by a +20-diopter indirect ophthalmoscopy lens in a setup similar to actual indirect smartphone retinal photography. Results: the spectrum of the LED flashlights of all tested smartphones fell entirely in the optically safe visible spectrum between 400-750 nm with no significant infrared or ultraviolet components. Two regions of main spectral distribution were noticed in all tested smartphones with a peak at 450 nm and the other ranging between 520 to 585 nm. Weighted irradiance was within the safe limits for ocular examination and ranged from 0.58 to 2.30 mW/cm2 (safe limit is up to 706 mW/cm2) without a measurable thermal effect. Conclusion: the LED flashlight of the tested smartphones appeared to be within safe limits when used for indirect smartphone retinal photography. However, the high composition of the short wavelength blue light spectrum may be a concern particularly with prolonged and repeated examinations.

Mitigation of photoreceptors abnormalities after low-level laser therapy and chia seeds supplementation in experimental diabetic retinopathy.

BACKGROUND: This study aimed to assess the effect of low-level laser therapy (LLLT) and chia seeds on the mitigation of photoreceptors abnormalities in experimental diabetic retinopathy (DR). MATERIALS AND METHODS: A total of 65 female Wistar rats, 5 rats were served as a control group and 60 rats were injected intraperitoneally with one dose of 55 mg/kg of streptozotocin (STZ) to induce DR after 6-8 weeks. The rats were divided into (n = 20 rats each): (a) DR group: did not receive any treatment, (b) DR+ LLLT group was exposed to 670-nm LLLT for 6 weeks (two sessions/week), and (c) DR+ LLLT+ chia seed group, in which rats were exposed to LLLT and administrated with 250 mg/kg/day of chia seeds flour for 2 weeks before STZ injection and continued to the end of the experiment. Blood glucose (BG) levels and retinal histological examination were employed after 1, 2, 4, and 6 weeks. RESULTS: The BG level in the DR group and the treated groups were significantly higher (P < 0.001) than in the control group after the four-time periods. Chia seeds group exhibited BG levels less than the DR and the DR+ LLLT groups after 6 weeks (P < 0.01). LLLT improved the degeneration of the photoreceptors after 6 weeks of treatment, while LLLT+ chia seeds supplementation showed early photoreceptors improvement after 2 weeks. CONCLUSION: The early improvement in the photoreceptors after LLLT+ chia seed may be attributed to the potent antioxidant properties of chia seeds. Therefore, the combination between LLLT and chia seeds should be employed to protect the retinal photoreceptors against DR.

Histopathological Changes of the Retina After Nd: YAG Laser Thrombolysis in Branch Retinal Vein Occlusion: An Experimental Study.

Introduction: The efficacy of many therapeutics techniques for treatment of branch retinal vein occlusion (BRVO) has been the subject of many investigations. The aim of the present work is to evaluate the transluminal Nd: YAG laser thrombolysis as a new therapeutic approach used for treatment of BRVO in rabbits as an experimental model. Methods: Four rabbits were considered as a control (n=8 eyes); occlusion of the branch retinal veins was performed by using a dye enhancing thrombus formation in right eyes of 10 rabbits (n=10 eyes). Thrombi in the retinal veins were induced by intravenous injection of rose bengal solution as a photosensitizer immediately before the argon laser application with a power of 1200 mW, a spot size of 100 µm, and a duration of 20 ms. One week later, transluminal Nd: YAG laser thrombolysis (30 mJ, 3 pulses/4 ns) was employed to the site of occluded veins, until the thrombi were partially or completely shattered. The rabbits were followed up after 4 days, 1 week and 2 weeks for slit lamp fundus examination and the treated retinas were isolated for histopathological examination. Results: Argon laser photothrombosis induced complete BRVO with some vitreous hemorrhage, destruction, and necrosis in the surrounding retinal layers. Moreover, one week later, Nd: YAG laser thrombolysis showed complete venous flow, minimal vitreous hemorrhage, reperfused retina, complete veins improvement. Follow up after 2 weeks revealed more improvement of all retinal layers. Conclusion: Treatment with transluminal Nd: YAG laser thrombolysis represented a novel therapeutic modality in BRVO.