Thrombospondin 1, thrombospondin 2 and the eye

Thrombospondin 1 and thrombospondin 2 (TSP1 and TSP2), which comprise the subgroup A thrombospondins, are matricellular proteins. As matricellular proteins, they modulate interactions between cells and the cellular environment, regulate cell adhesion and typically are expressed during tissue formative processes. In general, TSP1 and TSP2 counter angiogenesis (including tumour angiogenesis) and play important but contrasting roles during cutaneous repair. The two proteins are involved in development, including that of the eye, although evidence suggests that they have their greatest impact during tissue production in the adult. In the normal adult eye, they tend to be found at sites of ongoing matrix synthesis or cell-matrix interactions. At these sites, the two proteins possibly influence cellular differentiation and/or basement membrane deposition. TSP1 is also present in the intraocular fluids and drainage pathway, where it may function in maintaining the anti-angiogenic environment and in intraocular pressure control, respectively. TSP1 could also be involved in ocular immune privilege. Unlike in skin wounds, where TSP1 is derived from the blood and is present only in the early phases of repair, ocular tissue damage appears to lead to protacted TSP1 synthesis by local cells. This response might help suppress angiogenesis in the transparent tissues of the eye and so lessen visual axis opacification following injury. However, TSP2, which is also produced by damaged ophthalmic tissue and may be especially important in matrix organisation, seems to augment contraction in anomalous intraocular fibrosis. Elucidating the roles of TSP1 and TSP2 in ocular physiology and pathobiology may lead to improved therapies for neovascular, neoplastic, reparative and other ophthalmic diseases.     

Platelet-activating factor induces the gene expression of TIMP-1, -2, and PAI-1: imbalance between the gene expression of MMP-9 and TIMP-1 and -2

Previous studies in the laboratory have shown that platelet-activating factor (PAF), a potent inflammatory mediator that accumulates rapidly in the cornea after an injury, stimulates the expression of urokinase (uPA) and matrix metalloproteinase-1 (MMP-1) and -9 (MMP-9). Tissue inhibitors of MMPs (TIMPs) and plasminogen activator inhibitor (PAI-1) are produced in conjunction with these enzymes and are important regulators of their activity. Here, the authors investigated how PAF affects the expression of PAI-1, TIMP-1 and -2 relative to that of uPA, MMP-1, and -9 in rabbit corneal epithelial cells. Rabbit corneas were incubated in MEM medium containing 100 nM cPAF. To block the effects of PAF in some studies, corneas were preincubated for 1 hr in the presence of the PAF antagonist BN50730 (10 microM). At several time intervals, mRNA was extracted from epithelial cells and the levels of gene expression for the enzymes and their inhibitors were determined by real-time PCR. All quantitations were normalized to the 18s rRNA values (endogenous control) and changes in gene expression were reported as fold increase relative to untreated controls. PAF produced a 20-fold increase in the gene expression of PAI-1 at 8 hr, while similar fold increases in uPA mRNA expression occurred at 2 hr. PAF treatment also stimulated the expression of TIMP-1 and -2 genes, with a six-fold increase in TIMP-1 expression occurring at 36 hr and a four-fold increase in TIMP-2 expression at 24 hr. Maximal induction of MMP-1 and -9 mRNA, on the other hand, occurred at 4 and 8 hr, respectively. Induction of MMP-1 gene expression was similar to that of its inhibitors TIMP-1 and -2, while MMP-9 mRNA induction exceeded that of these inhibitors by 100-fold. The PAF-induced expression of PAI-1, TIMP-1 and -2 mRNAs was abolished by pre-treatment with BN50730. These data indicate that PAF activates the gene expression of TIMP-1, -2, and PAI-1 in corneal epithelium by a receptor-mediated mechanism. Furthermore, PAF induced overexpression of MMP-9 mRNA relative to that of TIMP-1 and -2, suggesting an imbalance between the expression of this proteolytic enzyme and its inhibitors, which may contribute to changes in the wound-healing process and ultimately lead to corneal ulcer development.     

Expression of P2Y1, P2Y2, P2Y4, and P2Y6 receptor subtypes in the rat retina

PURPOSE: To elucidate the expression pattern of different types of metabotropic P2Y receptors in the adult rat retina. METHODS: Qualitative RT-PCR was used to investigate the expression profile of different P2Y receptor subtypes (P2Y1, P2Y2, P2Y4, and P2Y6), and in situ hybridization studies were performed to show their cellular localization within the retina. Immunohistochemical staining was used to detect the corresponding P2Y proteins (P2Y1, P2Y2, and P2Y4) and their cellular localization. Southern blot analysis and sequencing verified the identity of the P2Y PCR products. RESULTS: RT-PCR revealed the presence of P2Y1, -2, -4, and -6 mRNA in the neural retina and the retinal pigment epithelium (RPE) and choroid. In situ hybridization showed labeling in the retinal ganglion cell layer for all four P2Y receptor subtypes, although the intensity varied. In addition, staining for P2Y1, -4, and -6 mRNA was shown in the inner nuclear layer, but was absent for the P2Y2 receptor subtype. Immunohistochemistry showed intense staining for P2Y1, -2, and -4 in the ganglion cell layer and the outer plexiform layer. There was also a specific subtype staining in the inner plexiform layer (P2Y2, -4), the inner (P2Y1, -4) and outer (P2Y1) nuclear layers and the inner segments of the photoreceptors (P2Y1, -2). discussion. The data suggest that extracellular nucleotides may play complex roles as autocrine-paracrine mediators and may have neuromodulatory effects in the retina through metabotropic P2Y receptors.     

Structural assessment of PITX2, FOXC1, CYP1B1, and GJA1 genes in patients with Axenfeld-Rieger syndrome with developmental glaucoma

PURPOSE: Axenfeld-Rieger (AR) is an autosomal dominant disorder with phenotypic heterogeneity characterized by anterior segment dysgenesis, facial bone defects, and redundant periumbilical skin. The PITX2 gene, on chromosome 4q25, and the FOXC1 gene, on chromosome 6p25, have been implicated in the different phenotypes of the syndrome through mutational events. Recently, the CYP1B1 gene was found to be associated with Peters' anomaly, and the gene associated with oculodentodigital dysplasia syndrome, which presents some similarities with AR, was identified (connexin 43--GJA1 gene). The purpose of this study was to evaluate PITX2, FOXC1, CYP1B1, and GJA1 gene mutations in Brazilian families with AR. METHODS: Eight unrelated patients affected by AR (all eight with glaucoma and three with systemic manifestations) and their families were ophthalmologically evaluated and their blood was collected for DNA extraction purposes. The coding regions of PITX2, FOXC1, CYP1B1, and GJA1 genes were completely evaluated through direct sequencing. RESULTS: The frequency of mutations in the FOXC1, GJA1, PITX2, and CYP1B1 genes in this study were 25%, 12.5%, 0% and 0%, respectively. In the FOXC1 gene, two GGC triplet insertions (GGC375ins and GGC447ins) defined as a polymorphism, and two new mutations--a deletion (718 to 719delCT) and a nonsense mutation (Trp152STOP)--were identified. One polymorphism (Ala253Val) was identified in the GJA1 gene in the same family presenting the Trp152STOP mutation in the FOXC1 gene. In this family harboring both structural alterations, two patients who carried the GJA1 (Ala253Val) and FOXC1 (Trp152STOP) mutations developed less severe glaucoma compared with family members presenting the FOXC1 (Trp152STOP) mutation alone. CONCLUSIONS: Two new structural alterations in the FOXC1 gene and a polymorphism in the GJA1 gene were first described in Brazilian patients with AR and developmental glaucoma. A polymorphism in the GJA1 gene (Ala253Val), for the first time identified in association with AR, raises the possibility of its participation as a modifier gene.     

翼状胬肉中MMP-2,TIMP-2和TGF-β1的表达意义

目的:探讨MMP-2及其抑制剂TIMP-2和影响它们作用的TGF-β1在翼状胬肉中的表达及意义。方法:采用Maxvision免疫组化技术检测在20例翼状胬肉和10例正常球结膜中MMP-2、TIMP-2及TGF-β1的表达,并比较两组中表达的差异。结果:MMP-2和TGF-β1在翼状胬肉中的表达的阳性率显著高于正常球结膜中它们的阳性表达率(z=-4.618,-4.376,P<0.01),而TIMP-2在两组中的表达差异无显著性(z=-1.319,P>0.05)。经Spearman等级相关检验分析,在翼状胬肉中,MMP-2和TGF-β1的阳性表达率存在正相关(r=0·686,P<0.01);而MMP-2和TGF-β1与TIMP-2阳性表达率之间无相关(r=-0.410,-0.143,P>0.05)。结论:TGF-β1介导的MMP-2和TIMP-2表达失衡在翼状胬肉的发生、发展及侵犯角膜过程中发挥着重要的作用。     

Cartesian and non-Cartesian responses in LGN,V1, and V2 cells

Cell responses to drifting Cartesian (parallel) and non-Cartesian (concentric, radial, and hyperbolic) stimuli were recorded in and beyond the classical receptive field (CRF) in the lateral geniculate nucleus (LGN), V1, and V2 of anesthetized monkeys. Many cells were equally responsive to Cartesian and non-Cartesian, especially concentric, gratings. Around 15% of cells in each area were significantly more responsive to concentric compared to parallel gratings; however, cells significantly more responsive to parallel compared to concentric gratings were more numerous in the cortex. While many cells responded to hyperbolic and radial gratings, few were most responsive to these gratings. Cell selectivity decreased for Cartesian and increased for non-Cartesian gratings from V1 to V2 and the relative response varied as a function of stimulus extent with respect to the CRE. Complex, nonoriented, nondirectional cells with a low aspect ratio (AR) responded best to non-Cartesian gratings. These results cannot be fully explained using Gabor linear/energy models of simple and complex receptive fields (RFs) although such models predict some cells to respond equally to Cartesian and non-Cartesian gratings. Cells significantly more responsive to non-Cartesian gratings can be accounted for by CRF selectivity influenced by modulation from the nonclassical receptive field (nCRF). The present study shows that Cartesian/non-Cartesian selectivity is not an emergent property of V4 cells but is present at all levels of early visual processing being subserved by a subset of cells with specific tuning properties.     

Gene polymorphisms of the MMP1, MMP9, MMP12, IL‐1β and TIMP1 and the risk of primary open‐angle glaucoma

Background: Primary open‐angle glaucoma (POAG) is the main cause of irreversible blindness worldwide. Matrix metalloproteinases (MMPs) and their regulators (TIMPs and ILs) have been extensively studied as POAG risk factors. Recent reports have showed several single‐nucleotide polymorphisms (SNPs) for MMPs, TIMPs and ILs encoding genes in patients with POAG. The aim of this study was to investigate association of the ‐1607 1G/2G MMP1, ‐the 1562 C/T MMP9, the ‐82 A/G MMP12, the ‐511 C/T IL‐1β and the 372 T/C TIMP1 gene polymorphisms with POAG occurrence and to investigate their impact on main clinical features. Material and methods: In the present case–control study, we examined group of 511 unrelated Caucasian subjects consist of 255 patients with POAG (mean age 70 ± 15) and 256 controls (mean age 67 ± 16). Determination of genes polymorphic variants was made using polymerase chain reaction–restriction fragment length polymorphism technique (PCR‐RFLP). The odds ratios (ORs) and 95% confidence intervals (CIs) for each genotype and allele were calculated. Results: Presented study showed statistically significant increase in the POAG development risk of the ‐1607 2G/2G MMP1 genotype (OR 1.75; 95% CI, 1.11–2.75; p = 0.014) and for the ‐1607 2G MMP1 allele (OR 1.35; 95% CI, 1.05–1.73; p = 0.017), as well as for the ‐1562 C/T MMP9 genotype (OR 1.74; 95% CI, 1.17–2.59; p = 0.006) and the ‐1562 T MMP9 allele (OR 1.55; 95% CI, 1.10–2.17; p = 0.012) in patients with POAG in comparison with healthy control group. We also observed positive association of the ‐511 T/T IL‐1β genotype (OR 2.60; 95% CI, 1.41–4.80; p = 0.002) as well as the ‐511 T IL‐1β allele occurrence with an increased POAG development risk (OR 1.47; 95% CI, 1.13–1.90; p = 0.003). Furthermore, we found an association of the ‐1607 1G/2G MMP1, ‐1562 C/T MMP9 (anova , p < 0.001) and the ‐511 C/T IL‐1β gene polymorphism (anova , p < 0.05) with decreased retinal nerve fibre layer (RNFL) thickness in patients with POAG group. Results displayed also an association of the 372 T/C TIMP1 gene polymorphism with normal range RNFL (anova , p < 0.001). We observed an association of decreased RA value (rim area) with the ‐82 A/G MMP12 (anova , p < 0.001). Normal RA value was observed in patients with POAG group connected with the 372 T/C TIMP1 (anova , p < 0.05) and the ‐511 C/T IL‐1β (anova , p < 0.05) genes polymorphisms occurrence. Finally, results showed an association of the ‐1562 C/T MMP9 (anova , p < 0.001) gene polymorphism with decreased cup/disc index in patients with POAG group. Conclusion: In conclusion, we suggest that the ‐1607 1G/2G MMP1, ‐1562 C/T MMP9, ‐511 C/T IL‐1β gene polymorphisms can be considered as an important risk factors associated with POAG.     

2'-nor-cGMP, a new cyclic derivative of 2'NDG, inhibits HSV-1 replication in vitro and in the mouse keratitis model

The present study examined the antiherpetic effect of 2'-nor-cGMP, a new cyclic phosphate derivative of 2'NDG, in vitro and in the mouse keratitis model. The 50% inhibitory dose (ID50) was determined with HSV-1 RE strain in Vero cell monolayers for 2'-nor-cGMP (6.9 mcg./ml), 2'NDG (.06 mcg/ml), and trifluridine (F3T) (.72 mcg/ml). Balb C mice underwent bilateral ocular inoculation with HSV-1 RE strain, and then were treated with different therapeutic regimens. The antiviral efficacy of each drug was evaluated by ocular virus titers, clinical grading of epithelial keratitis, and histological evaluation of stromal keratitis. 2'-nor-cGMP was the most effective drug (P = .0001) in reducing ocular viral titers. Both 2'-nor-cGMP and 2'NDG were significantly more effective (P = .0001) than F3T in reducing epithelial keratitis, and as effective as F3T in reducing stromal keratitis.     

Classifying the severity of corneal ulcers by using the "1, 2, 3" rule

PURPOSE: To propose and define the "1, 2, 3" rule as a system of categorizing the severity of bacterial keratitis and to determine its value in predicting the likelihood of visual loss after healing of bacterial corneal infection. METHODS: Seventy patients were evaluated for infectious corneal ulcers by 2 cornea subspecialists (J.D.L., M.C.V.) at a tertiary facility between October 30, 2001, and November 1, 2004. Forty-one patients met the inclusion criteria. Visual acuities, ulcer characteristics, culture results, and treatment data were collected. RESULTS: The sensitivity of the "1, 2, 3" rule for detecting potentially sight-threatening (PST) ulcers that would result in 0.20 logMAR (2 Snellen lines) or greater loss in best spectacle-corrected visual acuity (BSCVA) was 100%. The specificity of the "1, 2, 3" rule in correctly labeling an ulcer that did not cause vision loss as rarely sight threatening (RST) was 57.14%. The positive predictive value of the "1, 2, 3" rule was 28.57%. The negative predictive value of the "1, 2, 3" rule was 100%. CONCLUSIONS: Corneal ulcers classified as PST are at significantly higher risk for sustaining loss of BCSVA compared with RST corneal ulcers. The "1, 2, 3" rule is sensitive and specific enough to be clinically useful in predicting which ulcers are more likely to have vision loss and which ulcers are not.     

The different contributions of prostaglandins (E1, E2, F2alpha,D2) to the tone and neurogenic response of bovine iris sphincter muscle

The function and sites of action of prostaglandins (PGs) vary in different animal species and tissues. In this study the influence of PGs (E₁, E₂, F_2alpha, D₂) on muscle tone and nerve-mediated contraction was investigated in isolated bovine iris sphincter muscles.None of these PGs exogenously applied influenced the neuromuscular transmission. By contrast, after treatment with indomethacin, all PGs tested contracted the muscle much more than in the absence of indomethacin and under these conditions the PGs potentiated responses to cholinergic nerve stimulation. Their ED₅₀ were (2.2 ± 0.2) × ^–7 M for PGE₁, (6.7 ± 0.3) × ^–8M for PGE₂, and (7.3 ± 0.4) × ^–8 M for PGF_2alpha. PGE₁ acted both on nerves and the muscle cell. PGE₂ had its influence mostly via nerves. Whereas PGF_2alpha was less potent in the absence of indomethacin, PGF_2alpha had much more potent action primarily on nerves and partly on muscles after treatment with indomethacin. High concentrations of PGD₂ had both pre- and post-junctional action with accompanying weak contraction of the muscle. Thus the degrees of pre- and post-junctional involvement were different from one another.There is a possibility that the application of these PGs alone masked the role of such endogenous agents. In order to understand and clarify the site and action of PGs, pretreatment with indomethacin may be useful in the iris muscle. In conclusion, PGs modulate cholinergic activity in the bovine iris sphincter muscles, as well as regulate the muscle tone.     

Regulation of endotoxin-induced keratitis by PECAM-1, MIP-2, and toll-like receptor 4

PURPOSE: Bacterial lipopolysaccharide (LPS, endotoxin) is a potent stimulator of inflammatory responses and is likely to contribute to microbial keratitis and to the pathogenesis of sterile corneal ulcers. The purpose of the present study was to identify specific mediators of endotoxin-induced keratitis. METHODS: The corneal epithelium of BALB/c, C3H/HeJ, and C3H/HeN mice was abraded, and Pseudomonas aeruginosa endotoxin (10 microg in 1 microL) was added. Stromal thickness and haze were measured by in vivo scanning confocal microscopy, and neutrophil recruitment determined by immunohistochemistry. RESULTS: Pseudomonas endotoxin induced a significant increase in stromal thickness and haze compared with untreated control corneas at each time point examined, and the severity coincided with neutrophil infiltration into the corneal stroma. Furthermore, systemic depletion of neutrophils completely abrogated endotoxin-induced increases in stromal thickness and haze, indicating an essential role for these cells. Expression of platelet endothelial cell adhesion molecule (PECAM)-1 on vascular endothelium and production of macrophage inflammatory protein (MIP)-2 in the corneal stroma were also significantly elevated after exposure to endotoxin, and antibody blockade inhibited neutrophil recruitment to the cornea and abrogated endotoxin-induced increases in stromal thickness and haze. In LPS-hyporesponsive C3H/HeJ mice, PECAM-1 and MIP-2 were not upregulated after exposure to endotoxin, and endotoxin-induced keratitis did not develop in these mice. CONCLUSIONS: These findings demonstrate that endotoxin-induced keratitis is regulated by toll-like receptor-4 (TLR4)-dependent expression of PECAM-1 and MIP-2, which are essential for recruitment of neutrophils to this site and for development of endotoxin-induced stromal disease.     

CDKN2A,CDK1, and CCNE1 overexpression in sebaceous gland carcinoma of eyelid

Purpose

To investigate the overexpression of genes in sebaceous gland carcinoma (SGC) of the eyelid compared to sebaceous adenoma of the eyelid in order to elucidate the molecular mechanism underlying pathogenesis.

Methods

We performed histopathological examination of eyelid tissues surgically removed from four patients diagnosed with SGC (cases 1–3) and sebaceous adenoma (case 4) of the eyelid. Next, we performed global gene expression analysis of surgical tissue samples using a GeneChip^® system and the Ingenuity Pathways Knowledge Base. The results of the GeneChip^® analysis were explored with quantitative real-time polymerase chain reaction (qRT-PCR) analysis.

Results

In the SGC samples, we found that 211, 199, and 199 genes, respectively, showed?≥?2.0-fold higher expression than those in the sebaceous adenoma sample (case 4); 194 genes were common to all three SGC samples. For the 194 genes with upregulated expression, functional category analysis showed that SGC of the eyelid employed a unique gene network, including cyclin-dependent kinase inhibitor 2A (CDKN2A), cyclin-dependent kinase 1 (CDK1), and cyclin E1 (CCNE1), which are related to cell cycle progression, incidence of tumor, and cell viability. Furthermore, qRT-PCR analysis showed that the expression levels of CDKN2A, CDK1, and CCNE1 were significantly upregulated in all SGC cases compared to those in the sebaceous adenoma case. These data were similar to the results of microarray analysis.

Conclusion

Overexpression of cell cycle-related genes CDKN2A, CDK1, CCNE1, and their gene network may help elucidate the pathogenic pathway of SGC of the eyelid at the molecular level.

     

Effects of Th2 cytokines on expression of collagen,MMP-1, and TIMP-1 in conjunctival fibroblasts

PURPOSE: To determine whether cytokines involved in chronic allergic conjunctival disorders may affect formation of giant papillae and tissue remodeling. METHODS: Conjunctival fibroblast cultures were challenged with different concentrations of human recombinant interleukin (IL)-4, IL-13, interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha. Procollagens I (PIP) and III (PIIIP), matrix metalloproteinase (MMP)-1 and -9, and tissue inhibitor of metalloproteinase (TIMP)-1 were measured in supernatants, and their respective mRNAs were evaluated by RT-PCR. RESULTS: IL-4 and -13 (10 ng/mL) significantly increased production and expression of PIP compared with nonstimulated cells, whereas IFN-gamma elicited the opposite effect, at both the protein and mRNA levels. Both IL-4 and -13 significantly decreased production of MMP-1 and increased that of TIMP-1, whereas TNF-alpha increased production of MMP-1 and -9. Expression of MMP-1 was reduced by IL-4 and increased by the other tested cytokines, whereas expression of TIMP-1 was increased by all tested cytokines. CONCLUSIONS: IL-4 and -13 increased production of collagen and modified the equilibrium between MMP-1 and its inhibitor, TIMP-1. These effects were partially opposed by IFN-gamma and TNF-alpha.     

Effects of laser photocoagulation on serum angiopoietin-1, angiopoietin-2, angiopoietin-1/angiopoietin-2 ratio, and soluble angiopoietin receptor Tie-2 levels in type 2 diabetic patients with proliferative diabetic retinopathy

AIM: To determine the effects of laser photocoagulation on serum levels of angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), soluble angiopoietin receptor Tie-2 (Tie-2), Ang-1/Ang-2 ratio and vascular endothelial growth factor (VEGF) in patients with type 2 diabetes mellitus (T2DM) and proliferative diabetic retinopathy (PDR). We also explored the role of the Ang/Tie system in PDR.METHODS: 160 patients with T2DM, including 50 patients with non-diabetic retinopathy (NDR), 58 patients with non-proliferative diabetic retinopathy (NPDR), and 52 patients with PDR were enrolled in this study. Serum Ang-1, Ang-2, Tie-2 receptor and VEGF levels were measured using enzyme-linked immunosorbent assays for all patients and were repeated in 26 patients who underwent laser photocoagulation two months after the procedure.RESULTS: The median levels of Ang-2 and VEGF in serum were significantly higher in the NPDR group (4.23 ng/mL and 303.2 pg/mL, respectively) compared to the NDR group (2.67 ng/mL and 159.8 pg/mL, respectively, P<0.01), with the highest level in the PDR group (6.26 ng/mL and 531.2 pg/mL, respectively, P<0.01). The median level of Ang-1 was significantly higher in the NPDR group (10.77 ng/mL) compared to the NDR group (9.31 ng/mL) and the PDR groups (9.54 ng/mL) (P<0.05), while no difference was observed between the PDR and NDR groups. Ang-1/Ang-2 ratio of PDR group was lowest in three groups (1.49 vs 2.69 and 2.90, both P<0.01). The median level of Tie-2 was not significantly different among three groups (P>0.05). Ang-2 was positively correlated with VEGF and Tie-2 in the PDR and NPDR groups (both P<0.05). Among the 26 patients who underwent laser photocoagulation, serum Ang-2 and VEGF levels significantly decreased (both P<0.05), whereas serum Ang-1 level and Ang-1/Ang-2 ratio were weakly increased (P>0.05). The median levels of Ang-2 and VEGF in serum were highest in PDR group, however, Ang-1/Ang-2 ratio of PDR group was lowest in three groups.CONCLUSION: Laser photocoagulation can reduce serum Ang-2 and VEGF levels. The Ang/Tie system and VEGF play an important role in the development and progression of T2DM patients with PDR.     

The ocular pharmacokinetics of eicosanoids and their derivatives. 1. Comparison of ocular eicosanoid penetration and distribution following the topical application of PGF2 alpha, PGF2 alpha-1-methyl ester, and PGF2 alpha-1-isopropyl ester

These experiments were undertaken to determine whether the increased ocular hypotensive potency of topically applied prostaglandin (PG) PGF2 alpha esters, as compared with that of PGF2 alpha free acid, can be accounted for by increased penetration of the eicosanoid moiety of the esterified PG into the eye. One hour after the topical application of [3H]PGF2 alpha-1-methyl ester (ME) in peanut oil, the 3H activities in the cornea, aqueous humor, and ciliary body of the rabbit eye were 32-, 22-, and 8-fold higher, respectively, than they were following the topical application of [3H]PGF2 alpha free acid. 3H activity during the first 3 hr declined rapidly in the cornea and more slowly in the aqueous humor, but remained essentially constant in the ciliary body for up to 6 hr, declining rapidly only between 6- and 24 hr. 3H activity in eyes that received [3H]PGF2 alpha ME was also several-fold higher in the anterior sclera and iris than in eyes that were treated with [3H]PGF2 alpha free acid, but this difference was much smaller in the conjunctiva. At 1 hr, most of the 3H activity in the aqueous humor was associated with PGF2 alpha, as determined by chromatography, but at 2- and 3 hr other peaks, presumably reflecting metabolites of PGF2 alpha, became apparent. The penetration and intraocular distribution of 3H activity was similar when [3H]PGF2 alpha ME was applied to the eye in normal saline rather than in peanut oil or when the isopropyl rather than the methyl ester of PGF2 alpha was used. These studies indicate that esterification of the carboxyl group of PGF2 alpha greatly enhances the penetration of the PGF2 alpha moiety into the eye and suggests that effective de-esterification of the PGF2 alpha ester occurs in the cornea, resulting in the delivery of PGF2 alpha free acid into the aqueous humor. It is concluded that topically applied PG esters act as pro-drugs and that the increased ocular penetration of these esters may account for the previously reported increase in their ocular hypotensive potency as compared to that of PG free acid or salts.     

Natural outcomes of stage 1, 2, 3, and 4 idiopathic macular holes.

AIMS--A study was carried out to ascertain the natural outcome of each stage of idiopathic macular hole. METHODS--One hundred and fifty four eyes with different stages of idiopathic macular holes were retrospectively studied: stage 1 (40 eyes), 2 (25 eyes), 3 (58 eyes), and 4 (31 eyes). RESULTS--Of 27 of 40 eyes with a stage 1 lesion with posterior vitreous attachment to the macula initially, nine (33%) eyes developed a full thickness macular hole. No stage 1 lesions with posterior vitreous separation from the macula initially progressed to full thickness holes. Twenty one (84%) of 25 eyes with a stage 2 lesion, 32 (55%) of 58 eyes with a stage 3 lesion, and five (16%) of 31 eyes with a stage 4 lesion underwent macular hole enlargement during the median follow up period of 3 years. Visual acuity decreased two or more lines of Snellen equivalent during the follow up period in 12 (30%) eyes with a stage 1 lesion, 17 (68%) eyes with a stage 2 lesion, 17 (29%) eyes with a stage 3 lesion, and four (13%) eyes with a stage 4 lesion. The percentage was significantly higher in eyes with stage 2 lesions than the other stages (p < 0.01). CONCLUSION--The results suggest that the different stages of idiopathic macular holes have different natural outcomes, and the management depends on the stage at presentation.     

Intravitreal triamcinolone for diabetic macular edema: comparison of 1, 2, and 4 mg

PURPOSE: To compare the efficacy and safety of different doses of intravitreal triamcinolone (IVTA) in treating eyes with refractory diffuse diabetic macular edema (DME) with cystic changes. METHODS: Forty-five eyes of 45 patients with diffuse DME were randomized to receive 1, 2, or 4 mg IVTA. Patients were observed for 6 months and changes in best-corrected visual acuity (VA) in Early Treatment Diabetic Retinopathy Study (ETDRS) scores, retinal thickness analyzer (RTA) central macular thickness (CMT), intraocular pressure, and cataract progression were compared among the three groups. RESULTS: Forty-two patients completed 6 months of follow-up and were included in the analysis. Following IVTA injection, the ETDRS score improved similarly, eight to nine letters, in all three groups at 4 weeks. The standardized CMT improved in all three groups at 4 weeks. This improvement was maintained through 12 and 24 weeks in the 1 and 2 mg groups, but not in the 4 mg group, which was significantly worse than the 1 and 2 mg groups at 12 and 24 weeks (P = 0.01, 0.03, 0.01, and 0.05). CONCLUSIONS: Regarding eyes with refractory diffuse DME with cystic changes, 4 mg IVTA does not appear to be more effective than 1 or 2 mg IVTA.     

Comparative study of the effects of 2% ibopamine, 10% phenylephrine,and 1% tropicamide on the anterior segment

PURPOSE: To assess in normal and glaucomatous eyes the effect of the dopaminergic drug 2% ibopamine on visual acuity, IOP, pupil size and anterior segment geometry, compared with 10% phenylephrine and 1% tropicamide. METHODS: Fifteen healthy subjects and 15 patients with primary open-angle glaucoma, aged from 40 to 70 years (mean age: 54.8 +/- 9.6), were recruited into this open prospective study. After instillation of 2% ibopamine, refraction, visual acuity, pupil diameter, IOP, five A-scan ultrasonographic parameters, and 15 ultrasound biomicroscopy parameters were evaluated. The study was repeated with assessment of the same parameters 20 to 30 days later in 10 subjects (5 normal and 5 with glaucoma), using first 10% phenylephrine and then 1% tropicamide. A second group of 15 healthy subjects, aged from 45 to 70 years (mean age: 53.5 +/- 8.6) was examined to evaluate the dose-response effect and time course on pupil diameter, of ibopamine, phenylephrine, and tropicamide. RESULTS: After 40 minutes 2% ibopamine induced a marked mydriatic effect (from 5 to 9.1 mm; P < 0.0001) greater than that produced by 10% phenylephrine (from 4.7 to 7.9 mm; P < 0.0001) or 1% tropicamide (from 4.6 to 6.9 mm; P < 0.0001), with no changes in refraction or visual acuity. IOP was significantly increased only in patients with glaucoma after instillation of either 2% ibopamine (from 22.2 to 24.8 mm Hg; P < 0.0001) or 1% tropicamide (from 21.2 to 23.6 mm Hg; P = 0.004), whereas 10% phenylephrine induced no statistically significant changes. Ibopamine (2%) caused a significant increase in iris thickness with a reduction of the sulcus ciliaris and posterior chamber depth. The anterior chamber angle (ACA) showed a mean 5 degrees widening with an increase in scleral-iris angle (SIA) and sclera-ciliary process angle. In 11 (37%) of 30 cases, separation of the pupil border and lens surface occurred, whereas contact was maintained only with the zonule in the other 19 (63%) of 30. The changes after 10% phenylephrine instillation were similar, although only the increase in iris thickness and SIA was statistically significant. Tropicamide (1%) induced a slight but significant increase in SIA. CONCLUSIONS: The results confirm the potent mydriatic effect of 2% ibopamine, which is greater than that of either 10% phenylephrine or 1% tropicamide, as well as its ability to induce an increase in intraocular pressure when used in patients with glaucoma alone. These data support the hypothesis that the widening of the ACA induced by 2% ibopamine is due to posterior rotation of the iris plane and ciliary processes. These changes are quantitatively greater than those induced by 10% phenylephrine and 1% tropicamide and are related to the greater mydriatic effect of the drug.