A novel suprachoroidal microinvasive glaucoma implant: in vivo biocompatibility and biointegration.

BACKGROUND: A major challenge for any glaucoma implant is their ability to provide long-term intraocular pressure lowering efficacy. The formation of a low-permeability fibrous capsule around the device often leads to obstructed drainage channels, which may impair the drainage function of devices. These foreign body-related limitations point to the need to develop biologically inert biomaterials to improve performance in reaching long-term intraocular pressure reduction. The aim of this study was to evaluate in vivo (in rabbits) the ocular biocompatibility and tissue integration of a novel suprachoroidal microinvasive glaucoma implant, MINIject™ (iSTAR Medical, Wavre, Belgium). RESULTS: In two rabbit studies, no biocompatibility issue was induced by the suprachoroidal, ab-externo implantation of the MINIject™ device. Clinical evaluation throughout the 6 post-operative months between the sham and test groups were similar, suggesting most reactions were related to the ab-externo surgical technique used for rabbits, rather than the implant material itself. Histological analysis of ocular tissues at post-operative months 1, 3 and 6 revealed that the implant was well-tolerated and induced only minimal fibroplasia and thus minimal encapsulation around the implant. The microporous structure of the device became rapidly colonized by cells, mostly by macrophages through cell migration, which do not, by their nature, impede the flow of aqueous humor through the device. Time-course analysis showed that once established, pore colonization was stable over time. No fibrosis nor dense connective tissue development were observed within any implant at any time point. The presence of pore colonization may be the process by which encapsulation around the implant is minimized, thus preserving the permeability of the surrounding tissues. No degradation nor structural changes of the implant occurred during the course of both studies. CONCLUSIONS: The novel MINIject™ microinvasive glaucoma implant was well-tolerated in ocular tissues of rabbits, with observance of biointegration, and no biocompatibility issues. Minimal fibrous encapsulation and stable cellular pore colonization provided evidence of preserved drainage properties over time, suggesting that the implant may produce a long-term ability to enhance aqueous outflow.

Secretory proteostasis of the retinal pigmented epithelium: Impairment links to age-related macular degeneration.

Secretory proteostasis integrates protein synthesis, processing, folding and trafficking pathways that are essential for efficient cellular secretion. For the retinal pigment epithelium (RPE), secretory proteostasis is of vital importance for the maintenance of the structural and functional integrity of apical (photoreceptors) and basal (Bruch's membrane/choroidal blood supply) sides of the environment it resides in. This integrity is achieved through functions governed by RPE secreted proteins, which include extracellular matrix modelling/remodelling, angiogenesis and immune response modulation. Impaired RPE secretory proteostasis affects not only the extracellular environment, but leads to intracellular protein aggregation and ER-stress with subsequent cell death. Ample recent evidence implicates dysregulated proteostasis as a key factor in the development of age-related macular degeneration (AMD), the leading cause of blindness in the developed world, and research aiming to characterise the roles of various proteins implicated in AMD-associated dysregulated proteostasis unveiled unexpected facets of the mechanisms involved in degenerative pathogenesis. This review analyses cellular processes unveiled by the study of the top 200 transcripts most abundantly expressed by the RPE/choroid in the light of the specialised secretory nature of the RPE. Functional roles of these proteins and the mechanisms of their impaired secretion, due to age and genetic-related causes, are analysed in relation to AMD development. Understanding the importance of RPE secretory proteostasis in relation to maintaining retinal health and how it becomes impaired in disease is of paramount importance for the development and assessment of future therapeutic advancements involving gene and cell therapies.

Thrombospondin-2 is up-regulated by TGFß2 and increases fibronectin expression in human trabecular meshwork cells.

Elevated intraocular pressure (IOP) is a major risk factor for the development of primary open-angle glaucoma (POAG). This is from an increased aqueous humour (AH) outflow resistance through the trabecular meshwork (TM). The pathogenic mechanisms leading to the increase in TM outflow resistance are poorly understood but are thought to be from a dysregulation of the TM extracellular matrix (ECM) environment. ECM modification and turnover are crucial in regulating the resistance to aqueous outflow. ECM turnover is influenced by a complex interplay of growth factors such as transforming growth factors (TGFß) family and matrix metalloproteinases (MMPs). Elevated TGFß2 levels result in an increase in ECM deposition such as fibronectin leading to increased resistance. Fibronectin is a major component of TM ECM and plays a key role in its maintenance. Thrombospondins (TSP)-1 and -2 are important regulators of the ECM environment. TSP-1 has been implicated in the pathogenesis of POAG through activation of TGFß2 within the TM. TSP-2 does not contain the catalytic domain to activate latent TGFß, but is able to mediate the activities of MMP 2 and 9, thereby influencing ECM turnover. TSP-2 knock out mice show lower IOP levels compared to their wild type counterparts, suggesting the involvement of TSP-2 in the pathogenesis of POAG but its role in the pathogenesis of POAG remains unclear. The purpose of this study was to investigate the role of TSP-2 in trabecular meshwork ECM regulation and hence the pathogenesis of POAG. TSP-1 and TSP-2 expressions in immortalised glaucomatous TM cells (GTM3) and primary human non-glaucomatous (NTM) and glaucomatous cells (GTM) were determined by immunocytochemistry, immuno-blot analysis and qPCR following treatment with TGFß2 and Dexamethasone. The level of ECM protein fibronectin was determined in TM cells using immuno-blot analysis following treatment with TSP-1 or -2. TM cells secrete TSP-1 and -2 under basal conditions at the protein level and TSP-2 mRNA and protein levels were increased in response to TGFß2 three days post treatment. Exogenous treatment with TSP-2 up-regulated the expression of fibronectin protein in GTM3 cells, primary NTM and GTM cells. TSP-1 did not affect fibronectin protein levels in GTM3 cells. This suggests that the role of TSP-2 might be distinct from that of TSP-1 in the regulation of the TM cell ECM environment. TSP-2 may be involved in the pathogenesis of POAG and contribute to increased IOP levels by increasing the deposition of fibronectin within the ECM in response to TGFß2.

Advanced glycation end products-related modulation of cathepsin L and NF-κB signalling effectors in retinal pigment epithelium lead to augmented response to TNFα.

The retinal pigment epithelium (RPE) plays a central role in neuroretinal homoeostasis throughout life. Altered proteolysis and inflammatory processes involving RPE contribute to the pathophysiology of age-related macular degeneration (AMD), but the link between these remains elusive. We report for the first time the effect of advanced glycation end products (AGE)-known to accumulate on the ageing RPE's underlying Bruch's membrane in situ-on both key lysosomal cathepsins and NF-κB signalling in RPE. Cathepsin L activity and NF-κB effector levels decreased significantly following 2-week AGE exposure. Chemical cathepsin L inhibition also decreased total p65 protein levels, indicating that AGE-related change of NF-κB effectors in RPE cells may be modulated by cathepsin L. However, upon TNFα stimulation, AGE-exposed cells had significantly higher ratio of phospho-p65(Ser536)/total p65 compared to non-AGEd controls, with an even higher fold increase than in the presence of cathepsin L inhibition alone. Increased proportion of active p65 indicates an AGE-related activation of NF-κB signalling in a higher proportion of cells and/or an enhanced response to TNFα. Thus, NF-κB signalling modulation in the AGEd environment, partially regulated via cathepsin L, is employed by RPE cells as a protective (para-inflammatory) mechanism but renders them more responsive to pro-inflammatory stimuli.

Bovine posterior limbus: an evaluation of an alternative source for corneal endothelial and trabecular meshwork stem/progenitor cells.

A growing body of evidence has revealed that stem-like cells in the posterior limbus of the eye between the corneal endothelium (CE) and trabecular meshwork (TM) may be able to rejuvenate these tissues in disease. However, these cells have not been clearly defined and we have named them PET cells (progenitor cells of the endothelium and trabeculum). A good and inexpensive animal model for PET cells is lacking, so we investigated bovine eyes as an effective large tissue source. We showed the presence of stem/progenitor cells in the bovine CE, transition zone, and TM in situ. Floating spheres cultured from the CE and TM showed similar stem cell marker expression patterns. Both the CE and TM spheres were bipotent and highly proliferative, but with limited secondary sphere-forming capability. They were highly prone to differentiate back into the cell type of their tissue of origin. It is speculated that the PET cells become more tissue-specific as they migrate away from their niche. Here, we showed that PET cells are present in the posterior limbus of bovine eyes and that they can be successfully cultured and expanded. PET cells represent an attractive target for developing new treatments to regenerate both the CE and TM, thereby reducing the requirement for donor tissue for corneal transplant and invasive treatments for glaucomatous patients.

A Novel Schlemm's Canal Scaffold: Histologic Observations.

PURPOSE: To assess the biocompatibility of a novel implant made of Nitinol (nickel-titanium alloy), designed to improve aqueous humor outflow. MATERIALS AND METHODS: In the first arm of biocompatibility testing, microstents were surgically inserted into Schlemm's canal (SC) of 2 non-human primates (NHPs), and a third NHP served as a surgical sham control. After 13 weeks the animals were killed, and the eyes were examined by light and scanning electron microscopy. Two masked investigators evaluated the histology sections. The second arm utilized 8 New Zealand white rabbits; each rabbit received a microstent inserted into the sclera and subconjunctival space by means of passage across the anterior chamber thus providing contact with several representative ocular tissues. The fellow eye of each rabbit underwent a sham procedure without microstent insertion. The rabbits were killed after 26 weeks, and a trained ocular pathologist examined the specimens using light microscopy. RESULTS: Histologic and scanning electron microscopy analysis of the NHPs demonstrated that the microstents were located in SC. There was no evidence of an acute or chronic inflammatory response, granulation response, or fibrosis in the outflow system or in adjacent tissues. Rabbit eyes showed minimal mononuclear cell infiltration and minimal fibrotic responses at the site of the implants when compared with sham-treated control eyes. CONCLUSIONS: The Hydrus Microstent was associated with minimal inflammation in both NHP and rabbit eyes with extended follow-up. These preclinical studies demonstrate that the Hydrus Microstent appears to have excellent long-term biocompatibility.

Measurement and computer modeling of temporary arrangements of polygonal actin structures in trabecular meshwork cells which consist of cross-linked actin networks and polygonal actin arrangements.

PURPOSE: In trabecular meshwork (TM) cells, actin geodesic arrangements were measured and then subjected to computational modeling to appreciate the response of different dome shapes to mechanical force. METHODS: Polygonal actin arrangements (PAAs) and cross-linked actin networks (CLANs) were induced and imaged by Alexa Flour(®) 488 Phalloidin in bovine TM and human TM cells. Masked images were examined for size, circularity, and spoke and hub dimensions using ImageJ. Finite element modeling was used to create idealized dome structures and "realistic" PAA and CLAN models. The models were subjected to different loads simulating concentrated force and distortion measured. RESULTS: We provide evidence that PAAs and CLANs are not identical. Both structures formed flattened domes but PAAs were 6 times larger than CLANs, significantly more circular and had greater height. The dimensions of the triangulations of hubs and spokes were, however, remarkably similar. Hubs were around 2 µm(2) in area, whereas spokes were about 5 µm in length. Our modeling showed that temporary arrangements of polygonal actin structures (TAPAS) were because of their flattened shape, more resistant to shearing than compression when compared with idealized domes. CLANs were marginally more resistant to shearing than PAAs but because of size much more resistant to compression. CONCLUSIONS: Evidence is provided that there are 2 types of actin icosahedrons in cultured TM cells we collectively call TAPAS. Modeling suggests that TAPAS have rigidity and are better at dealing with shearing than compression forces. The 2 types of TAPAS, PAAs, and CLANs, have much in common but there are size and mechanical response differences that need to be taken into account in future experimentation.

Progenitors for the corneal endothelium and trabecular meshwork: a potential source for personalized stem cell therapy in corneal endothelial diseases and glaucoma.

Several adult stem cell types have been found in different parts of the eye, including the corneal epithelium, conjunctiva, and retina. In addition to these, there have been accumulating evidence that some stem-like cells reside in the transition area between the peripheral corneal endothelium (CE) and the anterior nonfiltering portion of the trabecular meshwork (TM), which is known as the Schwalbe's Ring region. These stem/progenitor cells may supply new cells for the CE and TM. In fact, the CE and TM share certain similarities in terms of their embryonic origin and proliferative capacity in vivo. In this paper, we discuss the putative stem cell source which has the potential for replacement of lost and nonfunctional cells in CE diseases and glaucoma. The future development of personalized stem cell therapies for the CE and TM may reduce the requirement of corneal grafts and surgical treatments in glaucoma.

Inducers of cross-linked actin networks in trabecular meshwork cells.

PURPOSE: It is well established that the unusual actin arrangements known as cross-linked actin networks (CLANs) can be induced by dexamethasone (DEX) in trabecular meshwork (TM) cells. Recent work reporting their presence in elderly glaucomatous and nonglaucomatous tissue, however, has highlighted the presence of other inducers. In this study, the authors sought to identify CLAN induction agents that may be present within and around the outflow system. METHODS: Studies were conducted on confluent bovine TM (BTM) cells in culture, and actin was stained with Alexa-Fluor 488 phalloidin to identify CLANs in the target cells. The CLAN-inducing potential of aqueous humor was expanded and included investigation of transforming growth factor-beta 2 (TGF-ß2). The effect of decorin and fetal calf serum (FCS) on BTM cell cytoskeleton was also investigated, and all were compared with DEX with an exposure period of up to 7 days. RESULTS: CLAN numbers were increased after 7 days of exposure to TGF-ß2 (45%), aqueous humor (37%), and decorin (69%). Even FCS had some modest CLAN-inducing ability (reaching 12%) in BTM cells. Neutralization of TGF-ß2 reduced CLAN incidence in aqueous humor conditions to baseline (12%) levels. Blocking TGF-ß2 receptors reduced CLAN formation in TM cells by 25% to 30%, whereas the inhibition of Smad3 negated CLAN incidence. CONCLUSIONS: In this study the authors identified TGF-ß2 as a CLAN-inducing component present in aqueous humor. Decorin was also implicated as another CLAN-inducing agent and it was confirmed that FCS has CLAN-inducing properties.

Cross-linked actin networks (CLANs) are present in lamina cribrosa cells.

AIMS: A study was undertaken to determine and compare the F-actin staining patterns in the cells of the lamina cribrosa (LC) of normal, dexamethasone (DEX)-treated and glaucomatous dissected tissue and cell cultures. METHODS: About 30 dissected donor eyes and nine cell lines provided the human specimens; 25 eyes and 20 primary cell cultures provided the bovine material. Appropriate samples were exposed to 1×10⁻7 M DEX for up to 14 days. LC tissue and cells were stained with Phalloidin-Alexa 488 to identify F-actin, and all samples were examined by confocal or epifluorescent microscopy. RESULTS: Both in the LC tissue and LC cell cultures the dominant actin arrangement was bundles of stress fibres. However, cross-linked actin networks (CLANs) were identified in the tissue and in culture. These were markedly increased by steroid treatment and were particularly large and abundant in cultures from glaucoma donors. CLANs were not associated with optic nerve head astrocytes. CONCLUSIONS: The presence of abundant stress fibres in situ and in vitro highlights the biomechanical contribution of LC cells. However, the identification of CLANs in these cells shows that they are not exclusive to the trabecular meshwork, the only other place they have been found, and may have a role in glaucoma pathology.

Cystatin C in macular and neuronal degenerations: implications for mechanism(s) of age-related macular degeneration.

Cystatin C is a strong inhibitor of cysteine proteinases expressed by diverse cells. Variant B cystatin C, which was associated with increased risk of developing age-related macular degeneration, differs from the wild type protein by a single amino acid (A25T) in the signal sequence responsible for its targeting to the secretory pathway. The same variant conveys susceptibility to Alzheimer disease. Our investigations of the trafficking and processing of variant B cystatin C in living RPE cells highlight impaired secretion of extracellular modulators and inappropriate protein retention in RPE cells as potential molecular mechanisms underpinning macular, and possibly neuronal, degeneration.

Spontaneous regression of human cancer cells in vitro: potential role of disruption of Cdk1/Cdk4 co-expression.

BACKGROUND: Although well-acknowledged in vivo, spontaneous death of cancer cells in vitro is less widely appreciated. MATERIALS AND METHODS: Colony formation was studied in untreated control plates of standard clonogenic assays and measurements of actual and potential doubling times performed in asynchronous cultures of human cancer cells lines. Western blotting of lung large cell carcinoma, COR-L23 cells actively undergoing spontaneous cell death was also carried out. RESULTS: Catastrophic disintegration of mature colonies could be seen in the untreated plates of lung large cell carcinoma, H460 and colon adenocarcinoma, SW620 human cancer cell lines and a significant cell loss factor was present in the cell lines growing as adherent cells in continuous culture. Western blotting demonstrated alterations of relative cyclin dependent kinase (Cdk)1 to Cdk4 protein expression in dying COR-L23 cells. CONCLUSION: The phenomenon of spontaneous cell death should be considered a hallmark of cancer and may be the result of failure to stabilise unstable, fully developed cancer cells due to the disruption of Cdk1/Cdk4 co-expression in those cells.

Cathepsin S and its inhibitor cystatin C: imbalance in uveal melanoma.

The present study aimed to investigate, as a follow-up of microarray profiling, the expression of the lysosomal cysteine protease cathepsin S and that of its endogenous inhibitor cystatin C in the most common primary intraocular tumor in adults, uveal melanoma. The expression pattern unveiled was characterized by a relative increase in the active form of the elastolytic and collagenolytic cathepsin S that was not counterbalanced by the expression of its strongest endogenous inhibitor cystatin C in the aggressive, highly metastatic uveal melanomas. The study provides evidence for a novel correlation between a specific cysteine protease activity and the strongest predictive factor for metastatic behavior in primary uveal melanoma and documents the first investigation of both a specific protease activity and its endogenous inhibitor in uveal melanoma. The results indicate that the shift in the balance between cathepsin S and cystatin C may be part of deregulated proteolytic pathways contributing to the invasive phenotype of uveal melanoma.

Cross-linked actin networks (CLANs) in the trabecular meshwork of the normal and glaucomatous human eye in situ.

PURPOSE: A percentage of trabecular meshwork (TM) cells in tissue and organ culture have been shown to contain cross-linked actin networks (CLANs) when exposed to dexamethasone, as have TM cultures derived from glaucomatous individuals. The purpose of this study was to determine whether CLANs exist within TM cells in situ in tissue unmanipulated by culturing, thereby eliminating the possibility that CLANs are artifacts of culture conditions, and to determine their numbers and dimensions in normal and glaucoma TM cells. METHODS: Twelve human donor eyes (five normal and seven with glaucoma) provided the TM tissue. Each eye was dissected, and the TM tissue was exposed either by microdissection (qualitative studies) or cryo-sectioning (quantitative analysis). The actin cytoskeleton was visualized using a high-affinity probe and viewed using confocal microscopy. RESULTS: Qualitative examination of the microdissected tissue revealed that CLANs and CLAN-like structures were a common finding in the TM cells in every specimen, irrespective of whether they were from normal or glaucomatous eyes. CLAN size and phenotype were variable, with the same variations occurring in both normal and glaucomatous eyes. Quantitative analysis showed that there were more CLANs in glaucoma TM specimens than normal TM specimens, but this difference was not statistically significant. The mean number of CLANs/TM cell in our glaucoma tissue was estimated to be 1.03, while in the elderly normal controls it was 0.67. CONCLUSIONS: This study showed for the first time that CLANs exist in cells of TM tissues from both normal and glaucomatous eyes that have not been manipulated by either tissue or organ culture procedures. It also provides quantitative data on CLAN prevalence in organized TM tissue, which indicates that CLANs are far more common than predicted (even from tissue culture) and there may be one in every cell in the glaucomatous TM in situ.

Prostaglandin analogues in the anterior eye: their pressure lowering action and side effects.

Topical application of prostaglandin (PG) analogues are currently the most commonly used intraocular pressure lowering drugs in glaucoma. They have been available since the mid 1990's, and are efficacious and generally well tolerated, the compliance rates are good due to the once a day application regime. The mode of action of PGs is by increasing the aqueous humour outflow primarily via the uveoscleral route, and also (but to a lesser degree) the conventional trabecular meshwork pathway. Increased outflow is primarily accomplished by remodelling the extracellular matrix components in both of the outflow pathways. PGs are associated with very few systemic side effects. The side effects of concern are all concentrated in the eye. Conjunctival hyperaemia is a common mild but transient complication. Since the development of this class of drug the most worrying and unusual side effect is a change in the pigmentation of the melanin-containing tissues close to the application site, i.e. eyelid skin, eyelashes and iris. As the prostaglandin induced iris darkening (PIID) is irreversible on cessation of the drugs it was of particular concern. We report here the findings from many studies which strongly indicate that there are no histopathological changes occurring in the iris tissue that has developed the darkening side effect. The only definitive change that has been detected in the cases of PIID is a small enlargement of the size of the existing melanin granule population and it has been shown that this change in melanin granule size is sufficient to account for the PIID. These findings point to the conclusion that the darkening developed following PG use is of a purely cosmetic effect with little or no serious consequences.

P53 apoptosis mediator PERP: localization, function and caspase activation in uveal melanoma.

p53 apoptosis effector related to PMP-22 (PERP) is a transcriptional target gene of p53 tumour suppressor that is specifically induced during apoptosis and not during cell cycle arrest. In primary uveal melanoma (UM), the most common intraocular malignancy in adults that has a reportedly unaffected signalling pathway upstream of and including p53, PERP expression is down-regulated in the metastatic monosomy 3-type tumours, compared with the less aggressive disomy 3-type tumours. Here, we demonstrate experimentally, by the use of full-length PERP-green fluorescent protein (GFP) fusions and real-time confocal microscopy, the intracellular targeting and plasma membrane localization of PERP in living UM cells and show that expression of PERP induces caspase-mediated apoptosis in UM cells. Induction of PERP expression in GFP-PERP-transfected UM cells leads to increased levels of cleaved caspase-8 forms, as well as to reduction of its full-length substrate Bid, but not to detectable processing of caspase-9. The levels of mature caspase-8, -9 and -3 proteins significantly correlate with PERP expression levels in primary UMs. Transcriptional profiling of PERP and caspase-8 in tumour specimens indicates that the positive association of PERP and caspase-8 proteins is a consequence of post-translational processing, most likely at the level of caspase-8 cleavage, and not of increased transcription of pro-caspase-8. We conclude that PERP expression leads to activation of an extrinsic receptor-mediated apoptotic pathway, with a possible subsequent engagement of the intrinsic apoptotic pathway. The findings underline the apoptotic pathway mediated by PERP as a critical mechanism employed by UM tumours to modulate susceptibility to apoptosis.

Side effects associated with prostaglandin analog therapy.

Topical prostaglandin analogs, which have become first-line therapy in the medical management of glaucoma, have an excellent safety profile with regard to systemic side effects, but are associated with several ocular side effects. Some of these are common, with no apparent serious consequences other than cosmetic, whereas others are much less common but represent potentially sight-threatening side effects. The former group includes conjunctival hyperemia, elongation and darkening of eyelashes, induced iris darkening, and periocular skin pigmentation. The latter group of side effects, which are relatively rare and lack definitive causal relationship to prostaglandin analog therapy, includes iris cysts, cystoid macular edema, anterior uveitis, and reactivation of herpes simplex keratitis. Most of the literature regarding side effects associated with prostaglandin analogs involves the use of latanoprost, probably because it was the first to be studied. There is no evidence, however, aside from less conjunctival hyperemia with latanoprost, that the commercially available prostaglandin analogs differ significantly with regard to side effects.

Long-term results of viscocanalostomy in pseudoexfoliative and primary open angle glaucoma.

PURPOSE: To document the outcome of viscocanalostomy (VC) alone or combined with phacoemulsification (phaco-VC) in eyes with pseudoexfoliation glaucoma (PEXG) and primary open angle glaucoma (POAG). METHODS: A prospective, comparative study of 314 eyes undergoing VC in two centres over 6 years was conducted. Main outcome measures were: (i) intraocular pressure (IOP) control (complete success was IOP < or = 18 mmHg without medication and failure IOP > 18 mmHg); and (ii) requirement for Nd:YAG laser goniopuncture (YAG-GP) if IOP > 21 mmHg. RESULTS: In the POAG group, 174 eyes underwent phaco-VC and 104 VC. In the PEX group, 20 eyes underwent phaco-VC and 16 VC. At final follow up, complete success rate (CSR) was 76% for POAG phaco-VC, 67% for POAG VC, 95% for PEXG phaco-VC and 63% for PEXG VC with mean IOP reduction of 29.9%, 40%, 42.5% and 51%, respectively. Without YAG-GP, by 3 years postoperatively the failure rate was 100% for PEXG eyes and 21% for POAG eyes undergoing VC alone, but PEXG eyes undergoing phaco-VC were 100% successful. CSR for YAG-GP was 92% in PEXG VC eyes and 55% in POAG VC eyes. CONCLUSIONS: In phakic eyes with PEXG undergoing VC, an absolute requirement for long-term success was YAG-GP. This was not the case in POAG eyes or PEXG eyes undergoing phaco-VC. Late IOP rise in phakic PEXG eyes and restoration of IOP control following YAG-GP suggests that continued release of PEX material from the lens capsule with time blocks the outflow through the trabecular-Descemetic window created by VC.

Expression of COX-2 and prognostic outcome in uveal melanoma.

PURPOSE: The expression of cyclooxygenase-2 (COX-2) and its prognostic value in uveal melanoma was examined. METHODS: Paraffin-embedded sections from 32 clinicopathologically well-characterized cases of primary uveal melanoma were immunohistochemically stained for COX-2. COX-2 expression was evaluated in terms of both the intensity and the extent of staining for each tumor. A COX-2 score encompassing both intensity and extent was also calculated for each specimen. RESULTS: 29 specimens (90.6%) contained moderate or intense positive immunoreactivity for COX-2. A statistically significant association (p<0.05) between COX-2 expression (intensity and score) and metastatic death was established. CONCLUSION: Upregulation of COX-2 expression appears to be associated with poor prognosis in uveal melanoma.

Multifocal electroretinography as a predictor of maintenance of vision after photodynamic therapy for neovascular age-related macular degeneration.

PURPOSE: To investigate the role of multifocal electroretinography (mfERG) in predicting the outcome of photodynamic therapy (PDT) for neovascular age-related macular degeneration (AMD). METHODS: Participants underwent refraction protocol VA assessment using the ETDRS logMAR chart at 1 m, Contrast Sensitivity (CS) using the Pelli-Robson chart at 1 m, fundus fluorescein angiography (FA) and mfERGs in response to 19 segments. Response to PDT was binary (1 = the loss of less than 15 letters at 12 months, 0 = the loss of 15 letters or more) and was used as the dependent variable for logistic regression analysis. RESULTS: Logistic regression modelling identified mfERG central segment amplitude, lesion size on FA, VA and CS as predictors of outcome (P = 0.05, 0.02, 0.01, 0.03). The model is stable and has excellent discriminability. CONCLUSION: The outcomes of this study are particularly relevant to patients in the UK who are sometimes treated with PDT alone. A larger prospective study would facilitate development of an index to predict outcome of future treatments for AMD.