Fábio Gasparin

New insights into Vogt-Koyanagi-Harada disease

Vogt-Koyanagi-Harada disease (VKH), a well-established multiorgan disorder affecting pigmented structures, is an autoimmune disorder of melanocyte proteins in genetically susceptible individuals. Several clinical and experimental data point to the importance of the effector role of CD4+ T cells and Th1 cytokines, the relevance of searching a target protein in the melanocyte, and the relevance of the HLA-DRB1*0405 in the pathogenesis of the disease. Vogt-Koyanagi-Harada disease has a benign course when early diagnosed and adequately treated. Full-blown recurrences are rare after the acute stage of Vogt-Koyanagi-Harada disease is over. On the other hand, clinical findings, such as progressive tissue depigmentation (including sunset glow fundus) and uveitis recurrence, indicate that ocular inflammation may persist after the acute phase. Additionally, indocyanine green angiography findings suggest the presence of choroidal inflammation in eyes without clinically detectable inflammation. The aim of this paper is to review the latest research results on Vogt-Koyanagi-Harada disease pathogenesis and chronic/convalescent stages, which may help to better understand this potentially blinding disease and to improve its treatment.

New approaches and potential treatments for dry age-related macular degeneration

Emerging treatments for dry age-related macular degeneration (AMD) and geographic atrophy focus on two strategies that target components involved in physiopathological pathways: prevention of photoreceptors and retinal pigment epithelium loss (neuroprotection induction, oxidative damage prevention, and visual cycle modification) and suppression of inflammation. Neuroprotective drugs, such as ciliary neurotrophic factor, brimonidine tartrate, tandospirone, and anti-amyloid β antibodies, aim to prevent apoptosis of retinal cells. Oxidative stress and depletion of essential micronutrients are targeted by the Age-Related Eye Disease Study (AREDS) formulation. Visual cycle modulators reduce the activity of the photoreceptors and retinal accumulation of toxic fluorophores and lipofuscin. Eyes with dry age-related macular degeneration present chronic inflammation and potential treatments include corticosteroid and complement inhibition. We review the current concepts and rationale of dry age-related macular degeneration treatment that will most likely include a combination of drugs targeting different pathways involved in the development and progression of age-related macular degeneration.

Experimental models of autoimmune inflammatory ocular diseases

Ocular inflammation is one of the leading causes of blindness and loss of vision. Human uveitis is a complex and heterogeneous group of diseases characterized by inflammation of intraocular tissues. The eye may be the only organ involved, or uveitis may be part of a systemic disease. A significant number of cases are of unknown etiology and are labeled idiopathic. Animal models have been developed to the study of the physiopathogenesis of autoimmune uveitis due to the difficulty in obtaining human eye inflamed tissues for experiments. Most of those models are induced by injection of specific photoreceptors proteins (e.g., S-antigen, interphotoreceptor retinoid-binding protein, rhodopsin, recoverin, phosducin). Non-retinal antigens, including melanin-associated proteins and myelin basic protein, are also good inducers of uveitis in animals. Understanding the basic mechanisms and pathogenesis of autoimmune ocular diseases are essential for the development of new treatment approaches and therapeutic agents. The present review describes the main experimental models of autoimmune ocular inflammatory diseases.

Vitreous pharmacokinetics and electroretinographic findings after intravitreal injection of acyclovir in rabbits

OBJECTIVES: Acute retinal necrosis is a rapidly progressive and devastating viral retinitis caused by the herpesvirus family. Systemic acyclovir is the treatment of choice; however, the progression of retinal lesions ceases approximately 2 days after treatment initiation. An intravitreal injection of acyclovir may be used an adjuvant therapy during the first 2 days of treatment when systemically administered acyclovir has not reached therapeutic levels in the retina. The aims of this study were to determine the pharmacokinetic profile of acyclovir in the rabbit vitreous after intravitreal injection and the functional effects of acyclovir in the rabbit retina. METHODS: Acyclovir (Acyclovir; Bedford Laboratories, Bedford, OH, USA) 1 mg in 0.1 mL was injected into the right eye vitreous of 32 New Zealand white rabbits, and 0.1 mL sterile saline solution was injected into the left eye as a control. The animals were sacrificed after 2, 9, 14, or 28 days. The eyes were enucleated, and the vitreous was removed. The half-life of acyclovir was determined using high-performance liquid chromatography. Electroretinograms were recorded on days 2, 9, 14, and 28 in the eight animals that were sacrificed 28 days after injection according to a modified protocol of the International Society for Clinical Electrophysiology of Vision. RESULTS: Acyclovir rapidly decayed in the vitreous within the first two days after treatment and remained at low levels from day 9 onward. The eyes that were injected with acyclovir did not present any electroretinographic changes compared with the control eyes. CONCLUSIONS: The vitreous half-life of acyclovir is short, and the electrophysiological findings suggest that the intravitreal delivery of 1 mg acyclovir is safe and well tolerated by the rabbit retina.

Pharmacokinetics, Electrophysiological, and Morphological Effects of the Intravitreal Injection of Mycophenolic Acid in Rabbits

PURPOSE To determine the half-life of mycophenolic acid (MPA) in the vitreous of New Zealand albino rabbits after intravitreal injection and the retinal toxicity of different doses of MPA. METHODS Ten micrograms of MPA (Roche Bioscience, Palo Alto, CA) was injected in the vitreous of 16 rabbits, animals were sacrificed at different time-points, and vitreous samples underwent high-performance liquid chromatography. For functional and morphological studies, 5 doses of MPA (0.05, 0.5, 2, 10, and 100 μg) were injected in the vitreous of 20 rabbits. As control, contralateral eyes were injected with aqueous vehicle. Electroretinograms (ERGs) were recorded before injection and at days 7, 15, and 30. Animals were sacrificed on day 30 and retinas were analyzed under light microscopy. RESULTS MPA half-life in the vitreous was 5.0±0.3 days. ERG revealed photoreceptor functional impairment in eyes injected with 0.5 μg and higher on day 30, while eyes injected with 100 μg presented the same changes already from day 15. No morphological change was found. CONCLUSIONS MPA vitreous half-life is 5.0 days. Intravitreal injection of 0.5 μg MPA and higher causes dose- and time-related photoreceptor sensitivity decrease in rabbits. The MPA dose of 0.05 μg may be safe for intravitreal use in rabbits.

In vitro evidence for mycophenolic acid dose-related cytotoxicity in human retinal cells.

Purpose: Mycophenolic acid (MPA) is an immunosuppressive agent that controls noninfectious uveitis. Intravitreal MPA delivery may be a potential adjuvant therapy in patients who have to discontinue steroid or immunosuppressive systemic therapy because of side effects. The aims of this study are to evaluate the in vitro effects of MPA over human retinal pigment epithelium (ARPE-19) and human Muller cells (MIO M-1). Methods: ARPE-19 cells and MIO M-1 cells were exposed to 25, 50, and 100 µg/mL of MPA (Roche Bioscience, Palo Alto, CA) for 24 hours. Toxicity was evaluated by trypan blue dye-exclusion cell viability assay, caspase-3/7 apoptosis-related assay, and JC-1 mitochondrial membrane potential assay. Results: The MPA (25 µg/mL and 50 µg/mL) did not cause reduction in cell viability or significant change in caspase-3/7 activity in both cell lines tested. Mycophenolic acid (100 µg/mL) caused a significant decrease in cell viability (P < 0.01) and higher caspase-3/7 activity (P < 0.05) in both cell lines compared with untreated cells. The JC-1 mitochondrial membrane potential did not show statistically significant differences for both cell lines and all concentration tested when compared with untreated controls (P > 0.05). Conclusion: Intraocular delivery may be a potential alternative for the treatment of noninfectious uveitis, either by intravitreal injection or sustained-release drug-delivery systems, in doses of 50 µg/mL or lower.

Use of intravitreal triamcinolone and laser photocoagulation for the treatment of diffuse diabetic macular edema

PURPOSE To assess the efficacy of intravitreal use of triamcinolone acetonide combined with laser photocoagulation for the treatment of diffuse diabetic macular edema and to compare it with the separate use of each treatment. METHODS After systemic clinical control, thirty patients with diffuse diabetic macular edema were divided into 3 treatment groups: (1) macular grid photocoagulation; (2) intravitreal injection of 4 mg of triamcinolone acetonide; (3) combination of the two previous therapies. Follow-up was scheduled at predetermined intervals of one day, one week and monthly until completion of six months. The following parameters were analyzed: LogMAR best corrected visual acuity, central macular thickness, total macular volume and intraocular pressure. RESULTS Grid photocoagulation did not significantly reduce the central macular thickness or the total macular volume. On the other hand, this reduction was statistically significant in the other two groups. All groups improved their mean visual acuity, however, the group that received both treatments had a higher percentage of patients that gained 10 or more letters. CONCLUSION The simultaneous administration of grid photocoagulation with intravitreal triamcinolone can be considered an option for the treatment of diffuse diabetic macular edema.

Lesões expansivas da órbita: distribuição de casos com estudo histopatológico em 11 anos no Hospital das Clínicas da FMUSP

PURPOSE To report the incidence of orbital space-occupying lesions in an 11-year interval study of patients examined at the Hospital das Clínicas of FMUSP, and to evaluate which are the main specialties involved in the diagnosis and treatment of such conditions. METHODS All cases of orbital space-occupying lesions in the period from 1993 to 2004 were revised. Of 924 obtained medical records, 155 were selected after histopathological analysis. Another 111 cases were gathered from the personal archives of a pathologist responsible for Ophthalmic Histopathology, from which 45 cases were excluded because they had already been included in the first source analysis. The data were analyzed and compared with the results from other institutions. RESULTS Of the studied 181 orbital space-occupying lesions, 70% were primary, 23% secondary, 6% metastatic and lymphomas, and 1% was not classified. The most common specialties involved ophthalmologists in 72.37% of all 181 cases, head and neck surgeons in 14.36%, neurosurgeons in 6.62%, and others in 6.62%. CONCLUSIONS The orbital mass lesions were treated mostly by an expert ophthalmologist. When other specialties were included, there was a modest increase in secondary tumor incidence when the final result was compared with previous studies on this subject. Our findings indicate that the creation of a trustworthy register of all orbital space-occupying lesions in Brazilian specialized services is necessary. The multidisciplinary character of the orbital mass lesions is corroborated by this review.

Intravitreal injection of polysorbate 80: a functional and morphological study

Objective: to determine the functional and morphological effects at rabbits retina of PS80 concentration used in the preparation of intravitreal drugs. Methods: eleven New Zealand rabbits received a intravitreal injection of 0.1ml of PS80. As control, the contralateral eye of each rabbit received the same volume of saline. Electroretinography was performed according to a modified protocol, as well as biomicroscopy and retina mapping before injection and seven and ten days after. Animals were euthanized in the 30th day and the retinas were analyzed by light microscopy. Results: eyes injected with PS80 did not present clinical signs of intraocular inflammation. Electroretinography did not show any alteration of extent and implicit time of a and b waves at scotopic and photopic conditions. There were no morphological alterations of retinas at light microscopy. Conclusion: intravitreal injection of PS80 in the used concentration for intravitreal drug preparations do not cause any functional or morphological alterations of rabbit retinas. These results suggest that PS80 is not toxic to rabbit retinas and may be safely used in the preparation of new lipophilic drugs for intravitreal injection.OBJECTIVE to determine the functional and morphological effects at rabbits retina of PS80 concentration used in the preparation of intravitreal drugs. METHODS eleven New Zealand rabbits received a intravitreal injection of 0.1ml of PS80. As control, the contralateral eye of each rabbit received the same volume of saline. Electroretinography was performed according to a modified protocol, as well as biomicroscopy and retina mapping before injection and seven and ten days after. Animals were euthanized in the 30th day and the retinas were analyzed by light microscopy. RESULTS eyes injected with PS80 did not present clinical signs of intraocular inflammation. Electroretinography did not show any alteration of extent and implicit time of a and b waves at scotopic and photopic conditions. There were no morphological alterations of retinas at light microscopy. CONCLUSION intravitreal injection of PS80 in the used concentration for intravitreal drug preparations do not cause any functional or morphological alterations of rabbit retinas. These results suggest that PS80 is not toxic to rabbit retinas and may be safely used in the preparation of new lipophilic drugs for intravitreal injection.

Importância da tomografia de coerência óptica e do eletrorretinograma na retinosquise senil

Retinoschisis diagnosis can be very difficult in atypical forms. Special exams are necessary to differentiate retinoschisis from other pathologies such as retinal detachment. Case Report: A 61-year-old black woman presented for routine examination. Fundus of the right eye reveled a superior periphery lesion extending to the posterior pole. The ultrassonography of the same eye showed a high reflective membrane. An inferior field absolute scotoma was detected. The OCT scan that was positioned at lesion in the outer retinal break demonstrated the fragmentation of the retinal layer. The scotopic ERG showed a reduction of the b wave amplitude of the right eye compared to the left eye (Negative electroretinogram). The multifocal ERG was normal in both eyes. The OCT demonstrated to be an useful toll to detect morphological alterations. The ERG and the absolute scotoma in the inferior field, demonstrated the retinal functional defect. A negative electroretinogram, showed a normal a wave and a reduced b wave demonstrating that the photoreceptor inner segments were relatively intact and that the initial damage in this disorder would seem to occur in the inner retinal layers. In doubtful cases especial exams are necessary and a careful investigation must confirm the diagnosis. The indications for treatment should be seriously analysed to avoid any intervention that can be harmful for the patients prognosis.