The reported rate of endophthalmitis after intravitreal anti-VEGF injection is low. Coagulase-negative Staphylococcus and Streptococcus species were the most frequent causative organisms. Streptococcus species represent the causative organism of endophthalmitis after intravitreal VEGF injections at a higher rate than rates reported in the literature for endophthalmitis following most incisional intraocular surgeries. Among patients with endophthalmitis after intravitreal anti-VEGF injection, endophthalmitis caused by Streptococcus species is associated with poorer visual acuity outcomes than endophthalmitis caused by coagulase-negative Staphylococcus and culture-negative cases.

Increased intraocular pressure (IOP) leads, by an unknown mechanism, to apoptotic retinal ganglion cell (RGC) death in glaucoma. We now report cleavage of the autoinhibitory domain of the protein phosphatase calcineurin (CaN) in two rodent models of increased IOP. Cleaved CaN was not detected in rat or mouse eyes with normal IOP. In in vitro systems, this constitutively active cleaved form of CaN has been reported to lead to apoptosis via dephosphorylation of the proapoptotic Bcl-2 family member, Bad. In a rat model of glaucoma, we similarly detect increased Bad dephosphorylation, increased cytoplasmic cytochrome c (cyt c), and RGC death. Oral treatment of rats with increased IOP with the CaN inhibitor FK506 led to a reduction in Bad dephosphorylation and cyt c release. In accord with these biochemical results, we observed a marked increase in both RGC survival and optic nerve preservation. These data are consistent with a CaN-mediated mechanism of increased IOP toxicity. CaN cleavage was not observed at any time after optic nerve crush, suggesting that axon damage alone is insufficient to trigger cleavage. These findings implicate this mechanism of CaN activation in a chronic neurodegenerative disease. These data demonstrate that increased IOP leads to the initiation of a CaN-mediated mitochondrial apoptotic pathway in glaucoma and support neuroprotective strategies for this blinding disease.retina ͉ optic nerve ͉ apoptosis

The current results confirm that Thy 1 mRNA levels do not reflect the number of RGCs present and extend this to include a parallel decrease in Thy1 protein levels. These results suggest that Thy1 serves as an early marker of RGC stress, but not a marker of RGC loss, in models of retinal damage.

In glaucoma, retinal ganglion cells (RGCs) die by apoptosis, generally attributed to an elevated intraocular pressure (IOP). We now describe the impact of elevated IOP in the rat on expression of caspase 8 and caspase 9, initiators of the extrinsic and intrinsic caspase cascades, respectively. Activation of both caspases was demonstrated by the presence of cleaved forms of the caspases and the detection of cleaved Bid and PARP, downstream consequences of caspase activation. Surprisingly, the absolute level of procaspase 9 was also elevated after 10 days of increased IOP. To examine the cause of increased levels of the procaspase, we used laser capture microdissection to capture Fluorogold back-labeled RGCs and real-time polymerase chain reaction to measure mRNA changes of initiating caspases. The mRNA levels of both caspase 8 and caspase 9 were increased specifically in RGCs. These data suggest that elevated IOP activates a transcriptional up-regulation and activation of initiating caspases in RGCs and triggers apoptosis through both extrinsic and intrinsic caspase cascades. The pathological hallmark of glaucoma is atrophy of the optic nerve associated with retinal ganglion cell (RGC) death, leading to vision loss and blindness throughout decades. The major risk factor for developing glaucoma is increased intraocular pressure (IOP). RGCs have been shown to die by apoptosis in both human 1,2 and animal models 3-5 although the exact mechanism(s) by which RGC apoptosis occurs in response to increased IOP is unknown. Two distinct pathways of upstream, initiating caspases can each begin a cascade that leads to activation of downstream effector caspases resulting in apoptosis. 6 Caspase 8 is the initial caspase activated by cleavage of procaspase 8 to the active form in response to extrinsic cell signaling, such as binding of receptors with death domains that interact with Fas-associated death domains (FADD). 7 The mitochondrial stress pathway on the other hand, begins with the release of cytochrome c from mitochondria, which then interacts with Apaf-1, causing cleavage and activation of caspase 9. 8 The extrinsic pathway (through the death receptors) and the intrinsic pathway (through the mitochondria) for apoptosis are capable of operating independently leading to the activation of downstream effector caspases, caspase 3, 6, and 7. Poly (ADP-ribose) polymerase (PARP) is a 116-kd nuclear protein that is involved in the repair of DNA and in differentiation and in chromatin structure formation. During the late stages of apoptosis, downstream caspases, such as caspase 3, cleave PARP to yield 85-kd and 25-kd fragments. 9 It is unclear which of the specific upstream molecular events occur in the retina under conditions of elevated IOP. In one report, caspase 8 was shown by immunohistochemistry to be activated in RGCs in experimental glaucoma in the rat. 10 In another report, we showed that caspase 9 is activated by immunohistochemistry in RGCs and by Western blot analysis under conditions of elevated IOP also in the rat. ...

These results confirm previous reports of elevated Hsp27 in experimental glaucoma and extend them to the DBA/2J mouse. In addition, a significant increase occurred in Hsp27 phosphorylation with elevated IOP in both models of glaucoma. IHC studies show that the increases in Hsp27 and pHsp27 occur primarily in glial cells.

These data support the hypothesis that calpain is activated under conditions of elevated intraocular pressure and provide further details of the pathologic events leading to RGC loss in glaucoma.

Retinal ganglion cells (RGCs) are the only output neurons of the retina, and their degeneration after damage to the optic nerve or in glaucoma is a well established system for studying apoptosis in the central nervous system. Frequently used procedures for assessing RGC number in retinal flat mounts suffer from two problems: RGC densities are not uniform across retinal flat mounts, and density measures may therefore not reflect total number, and flat mounts do not allow efficient use of tissue.To overcome these problems we developed a stereological method for efficiently assessing RGC number in cryostat sections of the retina. We empirically demonstrate that only ~1:20 sections need be assessed to accurately estimate the total number of RGCs in the rat retina, providing ample tissue for additional studies in the same retina and saving considerably on more exhaustive sampling strategies. Using this method, we estimate that there are 86,282 ± 4,759 RGCs in the normal BrownNorway rat retina. These counts match well with estimates of axon counts in optic nerve. In a pilot study of experimental glaucoma, we determined a reduction of RGCs to 53,862 ± 4272 (p<0.05). The current technique should prove advantageous to assess neuroprotective strategies in these experimental models.

A, An asymptomatic 12-year-old girl presented with unilateral dilated and tortuous retinal vessels. B, Optical coherence tomography demonstrates a dramatic pattern of circular lesions corresponding to cross-sections of abnormal retinal vessels. Findings are consistent with the diagnosis of Wyburn-Mason syndrome.