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The purpose of this study was to determine whether natural dyes facilitate posterior hyaloid detachment (posterior vitreous detachment [PVD]) and retinal internal limiting membrane (ILM) peeling in human eyes.Open-sky vitrectomy with posterior hyaloid and ILM removal was performed in 86 human cadaveric eyes. After core vitrectomy, 11 different dyes were injected into the vitreous cavity to aid hyaloid detachment and ILM removal. The dyes were allowed to settle on the macula for 5 minutes after PVD and were removed by mechanical aspiration. Intraocular forceps were used for ILM peeling, which was confirmed by light microscopy of the peeled tissue. Acai fruit (Euterpe oleracea) extract and 10 additional dyes from plants or animal sources were tested: pomegranate (Punica granatum), logwood (Haematoxylum campechianum), chlorophyll extract from alfalfa (Medicago sativa), cochineal (Dactylopius coccus), hibiscus (Hibiscus rosa-sinensis), indigo (Indigofera tinctoria), paprika (Capiscum annuum), turmeric (Curcuma longa), old fustic (Maclura tinctoria), and grape (Vitis vinifera).The dyes facilitated PVD and ILM peeling. Acai fruit (E. oleracea) extract, logwood (H. campechianum), cochineal (D. coccus), and old fustic (M. tinctoria) facilitated PVD in all cases; dye-assisted PVD was compared with triamcinolone-assisted PVD performed previously in a comparative model. Acai fruit (E. oleracea) extract, cochineal (D. coccus), and chlorophyll extract from alfalfa (M. sativa) showed the best capability for ILM staining; dye-assisted ILM removal was compared with the ILM peeling guided by indocyanine green staining performed previously in a comparative model. Light microscopy confirmed the ILM removal in all cases.Anthocyanin dye of the acai fruit (E. oleracea) and the dyes from cochineal (D. coccus) and chlorophyll extract from alfalfa (M. sativa) resulted in the best capability for posterior hyaloid and ILM staining in human cadaveric eyes and may be a useful tool for vitreoretinal surgery.

Sir, Leber’s hereditary optic neuropathy (LHON) is one of the best-studied mitochondrial diseases (for review see Carelli et al. , 2004; Yu-Wai-Mann et al. , 2011). Classically, there is a subacute loss of central vision that affects prevalently males, peaking in young adulthood. After a few months, optic atrophy becomes evident and the patient enters a chronic phase, in most cases characterized by stable blindness. Infrequently a partial recovery of visual acuity occurs. Exceptions have been reported. Concerning age of onset, childhood cases seem to represent a different version of LHON that often resembles dominant optic atrophy (Barboni et al. , 2006), whereas very late-onset cases have also been reported, widening the spectrum (Shah et al. , 2008; Yu-Wai-Man et al. , 2008; Giraudet et al. , 2011; Dimitriadis et al. , 2014). There is also a certain degree of heterogeneity in clinical expression, ranging from mild to severe cases, and the rates of spontaneous recovery of vision vary with mutation type (Carelli et al. , 2004, 2011; Yu-Wai-Mann et al. , 2011). A maternally inherited mitochondrial DNA (mtDNA) mutation is necessary but not sufficient to develop optic neuropathy. There are three common mtDNA mutations affecting complex I (i.e. m.11778G>A/MT-ND4, m.3460G>A/MT-ND1 and m.14484T>C/MT-ND6). Most cases remain as asymptomatic carriers, with males much more likely than females to undergo conversion to the affected state. Thus, male prevalence and incomplete penetrance remain areas of active investigation. Environmental factors have now been demonstrated as frequent triggers of the disease. The most common is tobacco smoke, in combination with or without alcohol consumption (Sadun et al. , 2003), as corroborated by Kirkman and colleagues (2009) with their large survey of LHON affected and unaffected mutation carriers. More rarely, exposure to toxins, various forms of smoke, or certain …

To evaluate the retinal penetration and toxicity of two doses of intravitreal infliximab in primates.Ten marmosets (Callithrix jacchus) were given intravitreal injection of 100 μg or 400 μg of infliximab, and balanced salt solution served as control. At baseline and after 24 hours (5 animals) and 7 days (the other 5), the eyes were examined by electroretinography. They were then killed (at 24 hours and 7 days) and assessed by light microscopy and transmission electron microscopy for toxicity and immunohistochemistry, using a biotinylated anti-human immunoglobulin G, to evaluate retinal penetration.There was no difference over 50% of the electroretinography b-wave between baseline and the time points studied in all animals. Light and electron microscopy, and electroretinography analysis, showed no signs of toxicity in any of the animals. Strong presence of infliximab was observed in all retinal layers 7 days after intravitreal injection at both doses (100 and 400 μg).Infliximab at doses of 100 and 400 μg seemed to cause no damage to the retina 24 hours and 7 days after its intravitreal injection, and deeply penetrated all its layers, in primates. These results encourage future perspectives for the treatment of chronic inflammatory diseases of the retina in humans.

Aims: Experimental retinal research has gained great importance due to the ophthalmic pharmacotherapy era. An increasing number of drugs are constantly released into the market for the treatment of retinal diseases. In this review, animal species, animal models and toxicity assays in retinal research are discussed. Methods: An extensive search of the literature was performed to review various aspects of the methods of investigation of drug toxicity. The different types of animal species, as well as single animal models available for the evaluation of safety and efficacy of retinal pharmacotherapy, were identified. In addition, a large variety of reported laboratory techniques were critically examined. Results: In vitro studies are the first-line experiments for the development of a new drug for retinal diseases, using retinal pigment epithelial cells and other cell lines. The next step involves in vivo animal studies where nonhuman primates are considered the gold standard. However, cost and legal issues make their use difficult. Mice and rats provide genetically controlled models for investigations. Pigs, dogs and cats represent good large-size animal models, while rabbits are one of the most used species for retinal toxicity evaluations. Various laboratory methods were identified, including light microscopy, electron microscopy, electroretinography and new emerging methods, such as optical coherence tomography and scanning laser ophthalmoscopy for experimental purposes. Conclusions: A great number of animal species and models are available that simulate retinal diseases and provide experimental data for further human use. Work with animal models should include properly designed toxicity assays to obtain reliable results for safety and efficacy.