Use of pegaptanib for recurrent and non-clearing vitreous haemorrhage in proliferative diabetic retinopathy.

PURPOSE: Diabetes is the leading cause of blindness in the United Kingdom among people of working age. Many with proliferative diabetic retinopathy (PDR) go on to develop vitreous haemorrhage (VH). Those with recurrent or non-clearing VH require vitrectomy to restore vision. Pegaptanib is a vascular endothelial growth factor antagonist that disrupts the proliferative cascade and has been shown to precipitate regression of retinal neovascularisation. We assessed the effect of pre-operative intravitreal (IVT) pegaptanib on the timing, difficulty, and outcome of vitrectomy for recurrent VH in PDR. METHODS: Fourteen consecutive patients (15 eyes) were given a course of 1-3 IVT pegaptanib injections and vitrectomy was performed when indicated by the recurrence or persistence of VH, or progression of associated tractional retinal detachment (TRD). RESULTS: The range of patient follow-up was from 6 months to 2 years. All had no further VH for at least 4 weeks after IVT pegaptanib. Five eyes remained free from VH until the end of the study (8-25 months), thus obviating the need for vitrectomy. Two further cases avoided vitrectomy following further IVT pegaptanib. In the majority of patients with VH, IVT pegaptanib created a window for further laser and risk factor optimisation. Surgery was faster and less challenging, compared with conventional vitrectomy for recurrent VH due to PDR. CONCLUSIONS: IVT pegaptanib can be considered in diabetic patients with VH. Approximately one-third may avoid vitrectomy altogether. There are clear intra-operative advantages of using IVT pegaptanib pre-operatively. However, caution should be exercised where there is pre-existing TRD.

The role of leptin in choroidal neovascularization.

PURPOSE: The purpose of this study was to investigate the role of leptin in choroidal neovascularization. METHODS: We examined the localization of leptin by immunohistochemistry in nine choroidal neovascular membranes surgically excised from patients with age-related macular degeneration, idiopathic choroidal neovascularization, and ocular histoplasmosis. Controls included omission of primary antibody, use of an irrelevant primary antibody and leptin staining of posterior segment of four normal donor eyes. RESULTS: Leptin was present in eight membranes and appeared vesicular, within the cytoplasm. The more vascular membranes and those consisting of a larger number of retinal pigment epithelium cells were associated with greater leptin staining. Leptin was not seen in the posterior segment of the four normal eyes. CONCLUSION: We suggest that leptin plays an active role in choroidal neovascularization, although further experiments are necessary to establish a causal relationship.

The effects of panretinal photocoagulation on the primary visual cortex of the adult monkey.

PURPOSE: To determine the effects of panretinal photocoagulation (PRP) on the levels of cytochrome oxidase (CO), Zif268, synaptophysin, and growth-associated protein 43 (GAP-43) in the primary visual cortex of adult monkeys. METHODS: Ten adult primates underwent unilateral argon laser PRP with instrument settings at 300 to 500 microns spot diameter, 200 to 500 mW power intensity, and 0.1 to 0.2 second duration, causing moderate to severe burns in the peripheral retina. At 20 hours, 12 days, 6 months, and 13 months after laser treatment, the visual cortex was assessed histologically for CO and immunohistochemically for Zif268, synaptophysin, and GAP-43. RESULTS: PRP resulted in transneuronal changes in the relative distributions of CO, Zif268, synaptophysin, and GAP-43 in the primary visual cortex. CO activity was relatively decreased in the lasered eye's ocular dominance columns at 12 days post-PRP, with recovery by 13 months post-PRP. The level of Zif268 was dramatically decreased in the lasered eye's ocular dominance columns at 20 hours post-PRP, with gradual recovery by 13 months post-PRP. Levels of synaptophysin and GAP-43 immunoreactivity were increased in both the lasered and the nonlasered eyes' ocular dominance columns at 6 months post-PRP. CONCLUSION: PRP treatment results in metabolic activity changes in the visual cortex of the adult monkey. These changes are followed chronologically by spatial redistribution of synaptophysin and GAP-43, neurochemicals known to play a role in cortical plasticity. This study demonstrates, for the first time, that PRP as used in the treatment of diabetic retinopathy results in a redistribution of neurochemicals in the adult monkey visual cortex. Such changes may help explain the anomalous visual functional loss often reported by patients after PRP.