ISOPT Clinical Hot Topic Panel Discussion on Glaucoma.

As part of the 14th International Symposium on Ocular and Pharmacological Therapeutics, a unique panel was gathered to discuss two cardinal questions related to the treatment of glaucoma, peeking into the future: (1) What shape and form will glaucoma medical treatment have five and fifteen years from today, and (2) Will personalized medicine be commonly used five years from now. For each of the questions, we assigned an "optimist" and "pessimist" who provided the assigned point of view, for a total of 4 discussants, the authors of this panel discussion.

SWITCHING TREATMENT FOR NEOVASCULAR AGE-RELATED MACULAR DEGENERATION FROM BEVACIZUMAB TO RANIBIZUMAB: Who is Likely to Benefit From the Switch?

PURPOSE: To evaluate the safety and efficacy of switching from bevacizumab to ranibizumab in patients with neovascular age-related macular degeneration. METHODS: Retrospective study of patients with neovascular age-related macular degeneration initially treated with bevacizumab and switched to ranibizumab. Visual acuity and central retinal thickness (CRT) were retrieved at four time points: before the last three bevacizumab injections, at the switch, after the first three ranibizumab injections, and at the end of follow-up. RESULTS: One hundred and fourteen eyes of 110 patients were included. Switching from bevacizumab to ranibizumab did not achieve a significant change in visual acuity, and a significant reduction in CRT was achieved after the first three injections but was not maintained by the end of follow-up. Eyes that lost ≥0.1 logMAR before the switch were more likely to improve in visual acuity (P = 0.013), and eyes with ≥10% increase in CRT before the switch were more likely to improve anatomically (P = 0.0003). In 47.3% of the eyes, the CRT was reduced by ≥10% after the first 3 ranibizumab injections, and the reduction was maintained with additional injections. CONCLUSION: Switching to ranibizumab should be considered in patients with visual acuity decrease or CRT increase, despite monthly bevacizumab injections. The response should be evaluated after the first three injections to guide future treatment.

A double-blind, randomized study of minocycline for the treatment of negative and cognitive symptoms in early-phase schizophrenia.

BACKGROUND: Current antipsychotics have only a limited effect on 2 core aspects of schizophrenia: negative symptoms and cognitive deficits. Minocycline is a second-generation tetracycline that has a beneficial effect in various neurologic disorders. Recent findings in animal models and human case reports suggest its potential for the treatment of schizophrenia. These findings may be linked to the effect of minocycline on the glutamatergic system, through inhibition of nitric oxide synthase and blocking of nitric oxide-induced neurotoxicity. Other proposed mechanisms of action include effects of minocycline on the dopaminergic system and its inhibition of microglial activation. OBJECTIVE: To examine the efficacy of minocycline as an add-on treatment for alleviating negative and cognitive symptoms in early-phase schizophrenia. METHOD: A longitudinal double-blind, randomized, placebo-controlled design was used, and patients were followed for 6 months from August 2003 to March 2007. Seventy early-phase schizophrenia patients (according to DSM-IV) were recruited and 54 were randomly allocated in a 2:1 ratio to minocycline 200 mg/d. All patients had been initiated on treatment with an atypical antipsychotic < or = 14 days prior to study entry (risperidone, olanzapine, quetiapine, or clozapine; 200-600 mg/d chlorpromazine-equivalent doses). Clinical, cognitive, and functional assessments were conducted, with the Scale for the Assessment of Negative Symptoms (SANS) as the primary outcome measure. RESULTS: Minocycline was well tolerated, with few adverse events. It showed a beneficial effect on negative symptoms and general outcome (evident in SANS, Clinical Global Impressions scale). A similar pattern was found for cognitive functioning, mainly in executive functions (working memory, cognitive shifting, and cognitive planning). CONCLUSIONS: Minocycline treatment was associated with improvement in negative symptoms and executive functioning, both related to frontal-lobe activity. Overall, the findings support the beneficial effect of minocycline add-on therapy in early-phase schizophrenia. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00733057.

Donor scleral patch for treating hypotony due to leaking and/or overfiltering blebs.

OBJECTIVE: To report a modified technique of bleb revision with the use of a donor scleral patch in cases in which scleral melting did not allow effective suturing and closure of the aqueous leak. The suturing technique ensures tight adaptation of the scleral patch over the leaky region, and allows better-controlled aqueous flow with loose suturing of the posterior edge of the scleral patch. METHODS: Records of patients who underwent bleb revision with donor scleral graft from 1997 to 2003 were reviewed retrospectively. Chart information including demographic and clinical data was recorded preoperatively and 1 day, 1 week, 1 month, 6 months, and at final follow-up. RESULTS: Fifteen patients underwent this surgical procedure for bleb revision. The mean follow-up time was 22.0 +/- 24.0 months (median = 8.0 months). The mean preoperative visual acuity was 20/50 and the mean intraocular pressure (IOP) was 2.9 +/- 2.3 mm Hg, which improved to 20/30 and 14.1 +/- 3.3 mm Hg respectively, on last follow-up. CONCLUSIONS: The scleral patch with 4-nylon sutures should be proposed in cases in which a macerated scleral bed is revealed during the revision. The loose suturing of the scleral patch at its posterior border was found to prevent intraocular pressure spikes.

The transcription factor c-jun is activated in retinal ganglion cells in experimental rat glaucoma.

This study investigates the role of the MAP kinase pathway including c-jun, ATF-2 and JNK in glaucomatous eyes of rats and in optic nerve transection. Glaucoma was induced in one eye of 51 adult Wistar rats by laser treatment to the trabecular meshwork. Eighteen further rats underwent unilateral optic nerve transection. We studied the transcription factor c-jun, its activated form, phospho-c-jun, the transcription factor p-ATF-2, and the enzyme JNK by immunohistochemistry. The activation of p-c-jun was also investigated using western blot analysis. Treated and control eyes were compared in a masked way at multiple time points after injury. We found a statistically significant increase in immunolabelling for c-jun and phospho-c-jun in retinal ganglion cells (RGCs) from 1 day to 4 weeks after intraocular pressure (IOP) elevation. At 1 and 2 days after the laser treatment, a mean of 2.9+/-3.3 RGCsmm(-1) were positive for c-jun (n=12, p=0.005, t-test), increasing to a mean of 13.4+/-7.5 cells mm(-1) at 1 week (n=18, p=0.00005), and decreasing to 2.3+/-2.0 cells mm(-1) at 2 weeks (n=5, p=0.04) and 0.1+/-0.1 cells mm(-1) at 2 months. Few of the 47 control eyes had any labelling for c-jun or phospho-c-jun, while between 80 and 100% of elevated IOP eyes showed positivity during the first 2 weeks of experimental glaucoma. After optic nerve transection, c-jun and phospho-c-jun were also significantly activated at 1, 2 and 9 days (p<0.03, t-test). Western blot analysis demonstrated significantly increased phospho-c-jun amounts in both transected and glaucomatous eyes compared to control fellow eyes 1 week following treatment. JNK was not significantly activated in glaucoma or optic nerve transection. P-ATF-2 was not significantly activated in glaucoma, but was significantly increased 2 days after optic nerve transection. We conclude that the process leading to RGC death in experimental glaucoma and after optic nerve transection involves the activation of c-jun at the RGC layer. C-jun is activated more gradually in glaucoma then after optic nerve transection.

Effect of glatiramer acetate on primary and secondary degeneration of retinal ganglion cells in the rat.

PURPOSE: After crush injury to the optic nerve, elevated intraocular pressure, and glutamate toxicity, the immune modulator glatiramer acetate (GA, Cop-1; Copaxone; Teva Pharmaceutical Industries, Pitach Tikva, Israel) has been shown to reduce the delayed cell death of retinal ganglion cells (RGCs). This study was undertaken to confirm the protective effect of GA on secondary degeneration of RGCs in the rat, by using a spatial, rather than temporal, model. METHODS: A total of 131 Wistar rats divided into 10 groups underwent bilateral stereotactic injection of fluorescent tracer (Fluorogold; Fluorochrome, Denver, CO) into the superior colliculus to label RGCs. They received a concurrent subcutaneously injection of (1) GA mixed with complete Freund's adjuvant (CFA), (2) CFA alone, or (3) saline. One week later, the superior one third of the left optic nerve was transected in animals in the six partial transection groups. Optic nerves in four additional groups underwent full transection. Rats were killed and retinas harvested from both eyes 1 or 4 weeks after partial transection and 1 or 2 weeks after full transection. RGC densities were calculated from retinal wholemounts, and differences between right (control) and left (transected) eyes were compared across treatment groups. RESULTS: Among the partial transection groups, differences in the mean percentage of RGC loss in the inferior retinas were not significant at 1 or 4 weeks (ANOVA; P = 0.20, P = 0.12, respectively). After full transection, there was significantly more RGC loss in the GA group than in the CFA group when comparing whole retinas at 1 week, but not at 2 weeks (two-tailed t-test; P = 0.04, P = 0.36, respectively). CONCLUSIONS: There is no evidence that GA has a neuroprotective effect after optic nerve transection, either for primarily injured or secondarily involved RGC.

Gene therapy with brain-derived neurotrophic factor as a protection: retinal ganglion cells in a rat glaucoma model.

PURPOSE: To develop a modified adenoassociated viral (AAV) vector capable of efficient transfection of retinal ganglion cells (RGCs) and to test the hypothesis that use of this vector to express brain-derived neurotrophic factor (BDNF) could be protective in experimental glaucoma. METHODS: Ninety-three rats received one unilateral, intravitreal injection of either normal saline (n = 30), AAV-BDNF-woodchuck hepatitis posttranscriptional regulatory element (WPRE; n = 30), or AAV-green fluorescent protein (GFP)-WPRE (n = 33). Two weeks later, experimental glaucoma was induced in the injected eye by laser application to the trabecular meshwork. Survival of RGCs was estimated by counting axons in optic nerve cross sections after 4 weeks of glaucoma. Transgene expression was assessed by immunohistochemistry, Western blot analysis, and direct visualization of GFP. RESULTS: The density of GFP-positive cells in retinal wholemounts was 1,828 +/- 299 cells/mm(2) (72,273 +/- 11,814 cells/retina). Exposure to elevated intraocular pressure was similar in all groups. Four weeks after initial laser treatment, axon loss was 52.3% +/- 27.1% in the saline-treated group (n = 25) and 52.3% +/- 24.2% in the AAV-GFP-WPRE group (n = 30), but only 32.3% +/- 23.0% in the AAV-BDNF-WPRE group (n = 27). Survival in AAV-BDNF-WPRE animals increased markedly and the difference was significant compared with those receiving either AAV-GFP-WPRE (P = 0.002, t-test) or saline (P = 0.006, t-test). CONCLUSIONS: Overexpression of the BDNF gene protects RGC as estimated by axon counts in a rat glaucoma model, further supporting the potential feasibility of neurotrophic therapy as a complement to the lowering of IOP in the treatment of glaucoma.

A model to study differences between primary and secondary degeneration of retinal ganglion cells in rats by partial optic nerve transection.

PURPOSE: To use a rat model of optic nerve injury to differentiate primary and secondary retinal ganglion cell (RGC) injury. METHODS: Under general anesthesia, a modified diamond knife was used to transect the superior one third of the orbital optic nerve in albino Wistar rats. The number of surviving RGC was quantified by counting both the number of cells retrogradely filled with fluorescent gold dye injected into the superior colliculus 1 week before nerve injury and the number of axons in optic nerve cross sections. RGCs were counted in 56 rats, with 24 regions examined in each retinal wholemount. Rats were studied at 4 days, 8 days, 4 weeks, and 9 weeks after transection. The interocular difference in RGCs was also compared in five control rats that underwent no surgery and in five rats who underwent a unilateral sham operation. It was confirmed histologically that only the upper optic nerve had been directly injured. RESULTS: At 4 and 8 days after injury, superior RGCs showed a mean difference from their fellow eyes of -30.3% and -62.8%, respectively (P = 0.02 and 0.001, t-test, n = 8 rats/group), whereas sham-operation eyes had no significant loss (mean difference between eyes = 1.7%, P = 0.74, t-test). At 8 days, inferior RGCs were unchanged from control, fellow eyes (mean interocular difference = -4.8%, P = 0.16, t-test). Nine weeks after transection, inferior RGC had 34.5% fewer RGCs than their fellow eyes, compared with 41.2% fewer RGCs in the superior zones of the injured eyes compared with fellow eyes. Detailed, serial section studies of the topography of RGC axons in the optic nerve showed an orderly arrangement of fibers that were segregated in relation to the position of their cell bodies in the retina. CONCLUSIONS: A model of partial optic nerve transection in rats showed rapid loss of directly injured RGCs in the superior retina and delayed, but significant secondary loss of RGCs in the inferior retina, whose axons were not severed. The findings confirm similar results in monkey eyes and provide a rodent model in which pharmacologic interventions against secondary degeneration can be tested.

Selective laser trabeculoplasty as primary treatment for open-angle glaucoma: a prospective, nonrandomized pilot study.

OBJECTIVE: To examine the safety and efficacy of selective laser trabeculoplasty as primary treatment for patients with open-angle glaucoma. METHODS: Forty-five eyes of 31 patients with open-angle glaucoma or ocular hypertension (intraocular pressure [IOP] >or=23 mm Hg on 2 consecutive measurements) underwent selective laser trabeculoplasty as primary treatment. All patients underwent complete ophthalmic evaluation before and at intervals after treatment. This evaluation included visual acuity, slitlamp examination, ophthalmoscopy, gonioscopy, and visual field analysis. The IOP was measured 1 hour, 1 day, 1 week, and 1, 3, 6, 12, 15, and 18 months postoperatively. During the follow-up period, patients were treated with topical antiglaucoma medications as required. RESULTS: Mean +/- SD decreased by 7.7 +/- 3.5 mm Hg (30%), from 25.5 +/- 2.5 mm Hg to 17.9 +/- 2.8 mm Hg (P<.001). Only 2 eyes (4%) did not respond to selective laser trabeculoplasty, and 3 eyes (7%) required topical medications to control their IOP at the end of the follow-up period. Forty eyes (89%) had a decrease of 5 mm Hg or more. Visual acuity, visual fields, and gonioscopic findings remained unchanged. Complications included conjunctival redness and injection within 1 day postoperatively in 30 eyes (67%). One hour after selective laser trabeculoplasty, an increase in IOP of more than 5 mm Hg was detected in 5 eyes (11%), while an increase in IOP between 2 and 5 mm Hg was measured in 3 eyes (7%). CONCLUSION: Selective laser trabeculoplasty is effective and safe as a primary treatment for patients with ocular hypertension and open-angle glaucoma.

Measurement of amino acid levels in the vitreous humor of rats after chronic intraocular pressure elevation or optic nerve transection.

PURPOSE: To investigate whether the levels of free amino acids and protein in the vitreous of rat eyes are altered with chronic intraocular pressure (IOP) elevation or after optic nerve transection. MATERIALS AND METHODS: The concentrations of 20 amino acids in the vitreous humor were measured by high-performance liquid chromatography in both eyes of 41 rats with unilateral IOP elevation induced by translimbal photocoagulation. Eyes were studied 1 day and 1, 2, 4, and 9 weeks after initial IOP elevation. The same amino acids were measured in 41 rats 1 day and 2, 4, and 9 weeks after unilateral transection of the orbital optic nerve. The intravitreal protein level was assayed in additional 22 rats with IOP elevation and 12 rats after nerve transection. Two masked observers evaluated the amount of optic nerve damage with a semiquantitative, light-microscopic technique. RESULTS: In rats with experimental glaucoma, amino acid concentrations were unchanged 1 day after treatment. At 1 week, 4 of 20 amino acids (aspartate, proline, alanine, and lysine) were higher than in control eyes ( < or = 0.01), but this difference was nonsignificant after Bonferroni correction for multiple simultaneous amino acid comparisons (none achieved < 0.0025). No amino acid was significantly different from control in the nerve transection groups (all > 0.05). Vitreous protein level was significantly higher in glaucomatous eyes than their paired controls at 1 day ( < 0.0001) and 1 week ( < 0.002). One day and 1 week after optic nerve transection, vitreal proteins were significantly elevated compared with control eyes from untreated animals ( < 0.0020 and < 0.0022, respectively), though not compared with their fellow eyes ( = 0.25 and 0.10). CONCLUSION: Chronic experimental glaucoma and transection of the optic nerve increase the amount of protein in the rat vitreous above control levels. In the vitreous of rats with experimental glaucoma, a number of free amino acids were transiently elevated to a modest degree, but no significant difference in vitreous glutamate concentration was detected ( > 0.01).

Retinal glutamate transporter changes in experimental glaucoma and after optic nerve transection in the rat.

PURPOSE: High levels of glutamate can be toxic to retinal ganglion cells. Effective buffering of extracellular glutamate by retinal glutamate transporters is therefore important. This study was conducted to investigate whether glutamate transporter changes occur with two models of optic nerve injury in the rat. METHODS: Glaucoma was induced in one eye of 35 adult Wistar rats by translimbal diode laser treatment to the trabecular meshwork. Twenty-five more rats underwent unilateral optic nerve transection. Two glutamate transporters, GLAST (EAAT-1) and GLT-1 (EAAT-2), were studied by immunohistochemistry and quantitative Western blot analysis. Treated and control eyes were compared 3 days and 1, 4, and 6 weeks after injury. Optic nerve damage was assessed semiquantitatively in epoxy-embedded optic nerve cross sections. RESULTS: Trabecular laser treatment resulted in moderate intraocular pressure (IOP) elevation in all animals. After 1 to 6 weeks of experimental glaucoma, all treated eyes had significant optic nerve damage. Glutamate transporter changes were not detected by immunohistochemistry. Western blot analysis demonstrated significantly reduced GLT-1 in glaucomatous eyes compared with control eyes at 3 days (29.3% +/- 6.7%, P = 0.01), 1 week (55.5% +/- 13.6%, P = 0.02), 4 weeks (27.2% +/- 10.1%, P = 0.05), and 6 weeks (38.1% +/- 7.9%, P = 0.01; mean reduction +/- SEM, paired t-tests, n = 5 animals per group, four duplicate Western blot analyses per eye). The magnitude of the reduction in GLT-1 correlated significantly with mean IOP in the glaucomatous eye (r(2) = 0.31, P = 0.01, linear regression). GLAST was significantly reduced (33.8% +/- 8.1%, mean +/- SEM) after 4 weeks of elevated IOP (P = 0.01, paired t-test, n = 5 animals per group). In contrast to glaucoma, optic nerve transection resulted in an increase in GLT-1 compared with the control eye (P = 0.01, paired t-test, n = 15 animals). There was no significant change in GLAST after transection. CONCLUSIONS: GLT-1 and GLAST were significantly reduced in an experimental rat glaucoma model, a response that was not found after optic nerve transection. Reductions in GLT-1 and GLAST may increase the potential for glutamate-induced injury to RGC in glaucoma.

Caspase activation and amyloid precursor protein cleavage in rat ocular hypertension.

PURPOSE: Retinal ganglion cell (RGC) death in glaucoma involves apoptosis. Activation of caspases and abnormal processing of amyloid precursor protein (APP) are important events in other chronic neurodegenerations, such as Alzheimer's disease (AD). The retinal expression and activation of caspases and the patterns of caspase-3-mediated APP processing in ocular hypertensive models of rat glaucoma were investigated. METHODS: RGC death was produced in one eye by chronic exposure to increased intraocular pressure (IOP) or by optic nerve transection. Elevated IOP was produced by obstruction of aqueous humor outflow with laser coagulation or limbal hypertonic saline injection. Caspase activity and APP processing in the retina were examined by RNase protection assay (RPA), immunocytochemistry, immunoblot assay, and colorimetric assay. RESULTS: RPA revealed elevations of caspase-3 mRNA, as well as other apoptosis-related mRNAs. Immunocytochemistry showed caspase-3 activation in RGCs damaged by ocular hypertension. The generation of the caspase-3-mediated APP cleavage product (DeltaC-APP) was also increased in ocular hypertensive RGCs. Western immunoblot assay and colorimetry revealed significantly more activated caspase-3 in ocular hypertensive retinas than in control retinas. The activated form of caspase-8, an initiator caspase, and amyloid-beta, a product of APP proteolysis and a component of senile plaques in AD, were detected in RGCs by immunohistochemistry significantly more often in ocular hypertensive than in control retinas. The amounts of full-length APP were reduced and amyloid-beta-containing fragments were increased in ocular hypertensive retinas by Western immunoblot assay. CONCLUSIONS: Rat RGCs subjected to chronic ocular hypertension demonstrate caspase activation and abnormal processing of APP, which may contribute to the pathophysiology of glaucoma.

Translimbal laser photocoagulation to the trabecular meshwork as a model of glaucoma in rats.

PURPOSE: To develop and characterize a model of pressure-induced optic neuropathy in rats. METHODS: Experimental glaucoma was induced unilaterally in 174 Wistar rats, using a diode laser with wavelength of 532 nm aimed at the trabecular meshwork and episcleral veins (combination treatment group) or only at the trabecular meshwork (trabecular group) through the external limbus. Intraocular pressure (IOP) was measured by a tonometer in rats under ketamine-xylazine anesthesia. Possible retinal vascular compromise was evaluated by repeated fundus examinations and by histology. The degree of retinal ganglion cell (RGC) loss was assessed by a masked, semiautomated counting of optic nerve axons. Effects of laser treatment on anterior ocular structures and retina were judged by light microscopy. RESULTS: After the laser treatment, IOP was increased in all eyes to higher than the normal mean IOP of 19.4 +/- 2.1 mm Hg (270 eyes). Peak IOP was 49.0 +/- 6.1 mm Hg (n = 108) in the combination group that was treated by a laser setting of 0.7 seconds and 0.4 W and 34.0 +/- 5.7 mm Hg (n = 46) in the trabecular group. Mean IOP after 6 weeks was 25.5 +/- 2.9 mm Hg in glaucomatous eyes in the combination group compared with 22.0 +/- 1.8 mm Hg in the trabecular group. IOP in the glaucomatous eyes was typically higher than in the control eyes for at least 3 weeks. In the combination group, RGC loss was 16.1% +/- 14.4% at 1 week (n = 8, P = 0.01), 59.7% +/- 25.7% at 6 weeks (n = 88, P < 0.001), and 70.9% +/- 23.6% at 9 weeks (n = 12, P < 0.001). The trabecular group had mean axonal loss of 19.1% +/- 14.0% at 3 weeks (n = 9, P = 0.004) and 24.3% +/- 20.2% at 6 weeks (n = 25, P < 0.001), increasing to 48.4% +/- 32.8% at 9 weeks (n = 12, P < 0.001). Laser treatment led to closure of intertrabecular spaces and the major outflow channel. The retina and choroid were normal by ophthalmoscopy at all times after treatment. Light microscopic examination showed only loss of RGCs and their nerve fibers. CONCLUSIONS: Increased IOP caused by a laser injury to the trabecular meshwork represents a useful and efficient model of experimental glaucoma in rats.