Unmasking of molecular players: proteomic profiling of vitreous humor in pathologic myopia.

BACKGROUND: This study aimed to identify the differentially expressed proteins in the vitreous humor (VH) of eyes with and without pathologic myopia (PM), providing insights into the molecular pathogenesis. METHODS: A cross-sectional, observational study was conducted. VH samples were collected from patients undergoing vitrectomy for idiopathic epiretinal membrane (ERM), macular hole (MH), or myopic retinoschisis (MRS). Label-free quantitative proteomic analysis identified differential protein expression, with validation using ELISA. RESULTS: The proteomic profiling revealed significantly higher expressions of tubulin alpha 1a (TUBA1A) and eukaryotic translation elongation factor 1 alpha 1 (EEF1A1) in PM groups (MH-PM, MRS-PM) compared to controls (MH, ERM). Conversely, xylosyltransferase 1 (XYLT1), versican core protein (VCAN), and testican-2 (SPOCK2) expressions were lower in PM. ELISA validation confirmed these findings. CONCLUSIONS: Our study provides novel insights into the molecular mechanisms of PM. The differentially expressed proteins EEF1A1, TUBA1A, XYLT1, VCAN, and SPOCK2 may play crucial roles in chorioretinal cell apoptosis, scleral extracellular matrix (ECM) synthesis, and scleral remodeling in PM. These proteins represent potential new targets for therapeutic intervention in PM, highlighting the importance of further investigations to elucidate their functions and underlying mechanisms in disease pathogenesis.

Metabolic characterization of human intraocular fluid in patients with pathological myopia.

Pathological myopia (PM) and its associated complications can lead to permanent vision loss. However, the cellular mechanisms underlying PM development remain unclear. To identify the metabolic alterations that may contribute to the pathophysiology of PM, we performed non-targeted metabolomics analysis using ultra-high-performance liquid chromatography with tandem mass spectrometry in age- and sex-matched patients with PM (n = 30) and individuals without myopia as controls (n = 30). Targeted metabolomics and insulin microarray were used to validate the results. We identified 508 metabolites in the aqueous humour (AH) and 601 in the vitreous humour (VH). Statistical evaluation revealed that 104 metabolites in AH and 114 metabolites in VH were significantly different between the two groups (variable important for the projection >1, fold change >1.5, or < 0.667, and P < 0.05). The four metabolic pathways enriched in both AH and VH identified to be associated with PM were: bile secretion, insulin secretion, thyroid hormone synthesis, and cGMP-PKG signaling pathway. The concentration of 10 amino acids was significantly higher in the PM than in the controls. Insulin microarray analysis showed that insulin, insulin-like growth factor 2 (IGF-2), IGF-2R, insulin-like growth factor binding protein 1 (IGFBP-1), IGFBP-2, IGFBP-3, IGFBP-4, and IGFBP-6 levels were significantly higher in PM patients compared to that in the controls. Thus, this study identified potential metabolite biomarkers for PM and provided novel insights into the mechanisms underlying this disorder.

Declines in PDE4B activity promote myopia progression through downregulation of scleral collagen expression.

Myopia is the most common cause of a visual refractive error worldwide. Cyclic adenosine monophosphate (cAMP)-linked signaling pathways contribute to the regulation of myopia development, and increases in cAMP accumulation promote myopia progression. To pinpoint the underlying mechanisms by which cAMP modulates myopia progression, we performed scleral transcriptome sequencing analysis in form-deprived mice, a well-established model of myopia development. Form deprivation significantly inhibited the expression levels of genes in the cAMP catabolic pathway. Quantitative real-time polymerase chain reaction analysis validated that the gene expression level of phosphodiesterase 4B (PDE4B), a cAMP hydrolase, was downregulated in form-deprived mouse eyes. Under visually unobstructed conditions, loss of PDE4B function in Pde4b-knockout mice increased the myopic shift in refraction, -3.661 ± 1.071 diopters, more than that in the Pde4b-wildtype littermates (P < 0.05). This suggests that downregulation and inhibition of PDE4B gives rise to myopia. In guinea pigs, subconjunctival injection of rolipram, a selective inhibitor of PDE4, led to myopia in normal eyes, and it also enhanced form-deprivation myopia (FDM). Subconjunctival injection of dibutyryl-cyclic adenosine monophosphate, a cAMP analog, induced only a myopic shift in the normal visually unobstructed eyes, but it did not enhance FDM. As myopia developed, axial elongation occurred during scleral remodeling that was correlated with changes in collagen fibril thickness and distribution. The median collagen fibril diameter in the FDM + rolipram group, 55.09 ± 1.83 nm, was thinner than in the FDM + vehicle group, 59.33 ± 2.06 nm (P = 0.011). Thus, inhibition of PDE4 activity with rolipram thinned the collagen fibril diameter relative to the vehicle treatment in form-deprived eyes. Rolipram also inhibited increases in collagen synthesis induced by TGF-ß2 in cultured human scleral fibroblasts. The current results further support a role for PDE enzymes such as PDE4B in the regulation of normal refractive development and myopia because either loss or inhibition of PDE4B function increased myopia and FDM development through declines in the scleral collagen fibril diameter.

Morphologic and biochemical changes in the retina and sclera induced by form deprivation high myopia in guinea pigs.

BACKGROUND: To study the morphologic and biochemical changes in the retina and sclera induced by form deprivation high myopia (FDHM) in guinea pigs and explore the possible mechanisms of FDHM formation. METHODS: Forty 3-week-old guinea pigs were randomized into the blank control (Group I, 20 cases) and model groups (20 cases). In the model group, the right eyes of the guinea pigs were sutured for 8 weeks to induce FDHM (Group II) and the left eyes were considered a self-control group (Group III). The refractive errors were measured with retinoscopy. The anterior chamber depth (AC), lens thickness (L), vitreous chamber depth (V) and axial length (AL) were measured using ultrasonometry A. Retinal and scleral morphology and ultrastructural features were observed with light and electron microscopy. The malondialdehyde (MDA) content and superoxide dismutase (SOD) activity in the retina and sclera were detected with a chemical colorimetric assay. RESULTS: After 8 weeks of stitching, the refractive errors of Group II changed from (+ 3.59 ± 0.33) D to (- 7.96 ± 0.55) D, and these values were significantly higher than those of Group I (+ 0.89 ± 0.32) D and Group III (- 0.55 ± 0.49) D (P < 0.05). The vitreous chamber depth (4.12 ± 0.13) mm and axial length (8.93 ± 0.22) mm of Group II were significantly longer than those of Group I [(3.71 ± 0.23) mm and (7.95 ± 0.37) mm, respectively] and Group III [(3.93 ± 0.04) mm and (8.01 ± 0.15) mm, respectively] (P < 0.05). With the prolongation of form deprivation (FD), the retina and scleral tissues showed thinning, the ganglion cell and inner and outer nuclear layers of the retina became decreased, and the arrangement was disordered. In Group II, the SOD activity was significantly lower than that in Group I and Group III; the MDA content was significantly higher than that in Group I and Group III. The differences were statistically significant (P < 0.05). CONCLUSIONS: These findings suggested that in the FDHM guinea pigs model, the refractive errors, the vitreous chamber depth, and axial length increased significantly with prolongation of monocular FD time, and morphological structural changes in the retina and sclera were observed. Oxygen free radicals might participate in the formation of FDHM.

Topical bendazol inhibits experimental myopia progression and decreases the ocular accumulation of HIF-1α protein in young rabbits.

PURPOSE: To investigate the inhibitory effect of bendazol on form-deprivation myopia (FDM) in rabbits as well as the underlying biochemical processes. METHODS: Forty-eight 3-week-old New Zealand white rabbits were randomly assigned to three groups: a control group, a form-deprivation (FD) group and an FD + bendazol group (treated with 1% bendazol in the FD eyes). Refraction, corneal curvature, vitreous chamber depth (VCD) and axial length (AL) were assessed using streak retinoscopy, keratometry, and A-scan ultrasonography, respectively. Eyeballs were enucleated for histological analysis, and ocular tissues were homogenized to determine the mRNA and protein expression of hypoxia-inducible factor-1α (HIF-1α) and muscarinic acetylcholine receptors (mAChRs). RESULTS: Bendazol inhibited the progression of FDM and suppressed the upregulation of HIF-1α. At week 6, in the control, FD and FD + bendazol groups, the refraction values were 1.38 ± 0.43, 0.03 ± 0.47 and 1.25 ± 0.35 D, respectively (p < 0.001); the ALs were 13.91 ± 0.11, 14.15 ± 0.06 and 13.97 ± 0.10 mm, respectively (p < 0.001) and the VCDs were 6.56 ± 0.06, 6.69 ± 0.07 and 6.61 ± 0.06 mm, respectively (p < 0.001). HIF-1α was upregulated in FD eyes but downregulated in FD + bendazol eyes, while the mAChRs were the opposite. CONCLUSIONS: In the FD rabbit model, bendazol significantly inhibits the development of myopia and downregulates HIF-1α expression, which may provide a novel therapeutic approach for myopia control.

Differential expression of connective tissue growth factor and hepatocyte growth factor in the vitreous of patients with high myopia versus vitreomacular interface disease.

BACKGROUND: To determine the levels of connective tissue growth factor (CTGF) and hepatocyte growth factor (HGF) in the vitreous of patients with high myopia, in comparison with those with a vitreomacular interface disease (VMID). METHODS: Patients with either high myopia (high myopia group) or a VMID (VMID group) were included in this study. Each of the two groups were further subdivided into two subgroups: group A (high myopia with macular hole), group B (high myopia with macular retinoschisis), group C (idiopathic macular hole), and group D (idiopathic epiretinal membrane). Vitreal specimens were collected during vitrectomy, and enzyme-linked immunosorbent assay was used to quantitatively measure the CTGF and HGF levels in the vitreous. RESULTS: The average axial length was markedly longer in the high myopia group than in the VMID group. The vitreal CTGF level was significantly higher in the high myopia group than in the VMID group. Subgroup analysis revealed significantly higher vitreal CTGF in group A than in the other three subgroups. The vitreal HGF level was not significantly different between the high myopia and VMID groups, but was significantly higher in group D than in group C in the subgroup analysis. Correlation analysis showed that the vitreal CTGF level was positively correlated with the axial length. CONCLUSIONS: The vitreal CTGF level is elevated in highly myopic eyes and may be related to the pathogenesis of high myopia, whereas increased expression of HGF may be involved in the development of idiopathic epiretinal membrane.

Iontophoresis-assisted accelerated riboflavin/ultraviolet A scleral cross-linking: A potential treatment for pathologic myopia.

Scleral collagen cross-linking is one of the most promising treatments to control the pathologic process of myopia. However, the exact procedure and its impact on animal models of myopia are still to be explored. We modified the scleral riboflavin/ultraviolet A (UVA) cross-linking procedure with an iontophoresis-assisted drug delivery system and an accelerated UVA irradiation (10 mW/cm2, 9 min) and applied this treatment to an animal model of myopia. Ninety-six New Zealand White rabbits developed relatively stable myopia by visual deprivation and then underwent the modified scleral cross-linking surgery. All the statistics and sample collection were obtained from 4 postoperative time points (1-day, 10-day, 1-month and 3-month groups). We found that the ultimate stress, Young's modulus and physiological Young's modulus of treated myopia sclera were significantly increased and maintained in 4 groups. The abnormal elongation of the myopic eye was effectively controlled 1 month after the treatment and even almost halted 3 months after the treatment. The histochemical assay revealed no notable post-surgery damage or apoptosis in the retina and choroid. Vigorous collagen synthesis was observed in scleral fibroblasts of the treated samples but were rarely observed in the untreated ones under electron microscopy. Furthermore, the remarkable difference in collagen gene expression and protein content between treated and untreated samples also indicated that an alteration in collagen metabolism may be triggered by the treatment. The effectiveness and safety exploration suggested that the modified scleral cross-linking procedure may be a potential method to control the pathologic process of myopia.

Metabolic characterization of human aqueous humor in relation to high myopia.

High myopia is the common eye disorder worldwide, which may contribute to increase the risk of serious disorders including glaucoma and cataract. Although various studies including genomics, transcriptomics, and proteomics have been implicated to identify potential biomarkers (genes or proteins) for predicting high myopia and to reveal the underlying mechanism, the comprehensive metabolomics in relation to high myopia is very limited. In this study, we identified 242 metabolites in aqueous humor (AH) from a set of 40 cataract patients (including 20 with high myopia and 20 for controls), using a non-targeted metabolomic technology, gas chromatography coupled to time-of-flight mass spectrometer (GC/TOF MS). Further statistical analysis showed that 29 metabolites were significantly changed (Variable important for the projection, VIP ≥ 1 and p ≤ 0.05), between those two groups, while only 2 decreased metabolites were included. Moreover, for the first time, metabolite-metabolite correlations for AH were analyzed, which may dissect key regulatory elements or pathways involved in metabolism of amino acids, carbohydrates, and lipids. Accordingly, metabolic network was constructed based on those 29 changed metabolites in patients with high myopia. More than half of the changed metabolites were highly and positively associated, suggesting important roles of pathways involved in the metabolism of these metabolites in relation to high myopia. Altogether, this work not only provided potential biomarkers for the diagnosis and monitoring of high myopia formation, but also provided new insights into the underlying mechanisms.

Riboflavin and ultraviolet A irradiation for the prevention of progressive myopia in a guinea pig model.

In this study, we evaluated the effect of oral administration of riboflavin combined with whole-body ultraviolet A (UVA) irradiation on the biochemical and biomechanical properties of sclera in a guinea pig model to control the progression of myopia. Experimental groups were administered 0.1% riboflavin solution with or without vitamin C by gavage from 3 days before myopic modeling and during the modeling process. Guinea pigs underwent 30 min of whole-body UVA irradiation after each gavage for 2 weeks. For control groups, guinea pigs were administered vitamin C and underwent either whole-body UVA irradiation without 0.1% riboflavin solution or whole-body fluorescent lamp irradiation with or without 0.1% riboflavin solution. Resultantly, myopia models were established with an increased axial length and myopic diopter. Compared with myopic eyes in the control groups, the net increase in axial length, diopter and strain assessment decreased significantly, and the net decrease in sclera thickness, ultimate load, and stress assessment decreased significantly in experimental groups. MMP-2 expression showed a lower net increase, while TIMP-2 expression showed a lower net decrease. In addition, hyperplasia of scleral fibroblasts was more active in myopic eyes of experimental groups. Overall, our results showed that oral administration of riboflavin with whole-body UVA irradiation could increase the strength and stiffness of sclera by altering the biochemical and biomechanical properties, and decreases in axial elongation and myopic diopter are greater in the guinea pig myopic model.

Intraocular Cytokines and Their Correlations with Clinical Parameters in Patients with Myopic Choroidal Neovascularization.

PURPOSE: To study cytokine levels in aqueous humor of patients with myopic choroidal neovascularization (mCNV), their correlations with each other and ocular parameters. METHODS: Ophthalmological examination and immunological study of aqueous humor with cytokine levels measurement (Bio-Plex™ Human Cytokine 27-Plex panel; Bio-Rad Laboratories, USA) were performed in 19 patients (19 eyes) with ranibizumab-treated mCNV and compared to 15 patients (15 eyes) with myopia without CNV. RESULTS: The levels of 10 cytokines were significantly different in patients with mCNV compared to the controls: the vascular endothelial growth factor (VEGF) level was 2 times lower (191.15 ± 142.30 and 320.06 ± 170.05 pg/mL, respectively), and the levels of PDGF, IL-2, IL-5, IL-13, IL-15, IL-17А, TNF-α, IL-8, and RANTES were elevated. Strong correlations between morphological and functional parameters and cytokines, including VEGF, were found. The VEGF level inversely correlated with the myopia degree and the cytokines IL-13, INF-γ, and RANTES. CONCLUSION: The decrease in VEGF levels accompanied by imbalance of other cytokines may suggest additional mCNV development pathways.

Cortical Representation of a Myopic Peripapillary Crescent.

PURPOSE: To determine how formation of an acquired myopic crescent adjacent to the optic disc affects metabolic activity in the primary visual cortex. DESIGN: Laboratory animal study. PARTICIPANTS: Three macaque monkeys. METHODS: The blind spot region in the primary visual cortex was labeled by cytochrome oxidase (CO) histochemistry analysis or [(3)H]proline autoradiography. MAIN OUTCOME MEASURES: Visualization of the representation of the blind spot and myopic peripapillary crescent in the visual cortex. RESULTS: In high myopia, a region resembling the myopic peripapillary crescent was visible in cortical sections processed for CO. In this region, metabolic activity was reduced in ocular dominance columns that normally would be driven by input from retina corresponding to the myopic peripapillary crescent. CONCLUSIONS: The formation of a myopic crescent is accompanied by loss of metabolic activity in the cortex supplied by the affected retina. This observation confirms that retinal tissue is damaged by the development of a myopic crescent, rather than simply translocated in a temporal direction. The cortical defect matches the myopic peripapillary crescent in size and shape, indicating that fill-in of the retinotopic map by healthy, surrounding retina does not occur.

Proinflammatory status in the aqueous humor of high myopic cataract eyes.

High myopia has long been recognized as an inflammation-related disease, and high myopic eyes are thought to have a proinflammatory internal microenvironment, which might predispose to the occurrence of certain inflammation-related complications such as fibrotic capsular contraction syndrome after cataract surgery. Therefore, the purpose of this study was to detect inflammatory cytokines expressed in the aqueous humor (AH) of high myopic cataract (HMC) patients. The cytokines were screened using a RayBio Human Cytokine Antibody Array in AH samples from 15 age-related cataract (ARC) patients and 15 HMC patients. Those detected by the screening assays were verified using a Bio-Plex Suspension Array System in AH samples from 35 ARC patients and 45 HMC patients. The cytokine antibody array showed that the expression level of interleukin-1 receptor antagonist (IL-1ra) in the AH was higher in ARC than in HMC, whereas opposite trends were found for monocyte chemoattractant protein-1 (MCP-1), regulated on activation, normal T-cell expressed and presumably secreted (RANTES), IL-8, platelet-derived growth factor-BB, and IL-6 (all P < 0.05). In the verification assay using the suspension cytokine array, only the expression levels of IL-1ra and MCP-1 were significantly different between the ARC and HMC groups (P = 0.014 and 0.038, respectively); these results were confirmed by western blot assays. Our results demonstrated that the expression of IL-1ra was significantly lower and the expression of MCP-1 was significantly higher in the AH of HMC than in ARC, suggestive of a proinflammatory status in the anterior chamber of HMC eyes.

Abnormal pigment epithelium-derived factor processing in progressive myopia.

Pigment Epithelium-Derived Factor (PEDF) is a secreted glycoprotein belonging to the family of non-inhibitory serpins. It is known, that in cases of complicated myopia, the content of PEDF in aqueous humor of the anterior chamber is significantly reduced. Here we examined a bulk of Tenon's capsule samples obtained from various groups of myopes, to examine PEDF processing in progressive myopia. We have analyzed the distribution of full length PEDF50 and its truncated form PEDF45 in the soluble and insoluble fractions extracted from Tenon's capsule of myopic and control (non-myopic) patients using SDS-polyacrylamide gel electrophoresis, as well as monitored the proteolytic degradation of PEDF ex vivo by enzyme-linked immunosorbent assay. These results were complemented by PEDF mRNA analysis in correspondent tissues by using qPCR and immunohistochemistry analysis of PEDF distribution in normal and myopic specimens. We found that in the Tenon's capsule of patients suffering from a high myopia the level of "soluble" 45 kDa PEDF reduced by 2-fold, while the content of "insoluble" 50 kDa form of PEDF was increased by 4-fold compared to controls. Excessive amount of PEDF50 in myopic specimens have been shown to correlate with the abrogated PEDF processing rather than with an increase of its expression. Moreover, immunohistochemical staining of the myopic Tenon's capsule tissue sections revealed the halo of deposited PEDF50 in the fibroblast extracellular space. These findings suggest that in myopia limited proteolysis of PEDF is altered or abrogated. Accumulation of full-length PEDF insoluble aggregates in the fibroblast intercellular space may affect cell survival and consequently causes the destructive changes in the extracellular matrix of the eye connective tissues. As a result, the abrogation of full-length PEDF normal processing can be an important mechanism leading to biomechanical destabilization of the scleral capsule and myopia progression.

Associations of inflammatory cytokines with choroidal neovascularization in highly myopic eyes.

PURPOSE: To determine the relationships between the levels of intraocular inflammatory cytokines and the clinical characteristics of myopic choroidal neovascularization (mCNV) in eyes with myopic maculopathy. METHODS: One hundred eyes of 100 cases, including 51 mCNV eyes, 14 highly myopic eyes without choroidal neovascularization, and 35 normal subjects, were studied. The intraocular levels of choroidal neovascularization-related cytokines, like vascular endothelial growth factor, MCP-1, IL-8, IL-10, and IL-23, were determined. RESULTS: The levels of vascular endothelial growth factor and IL-8 were significantly higher in eyes with mCNV than in high myopia eyes without mCNV with significant odds ratio of 2.00 and 2.25 per quartile, respectively (P < 0.05). When myopic lesions of patients with mCNV were classified into 3 categories based on the severity, IL-8 and MCP-1 were significantly elevated depending on the presence of maculopathy (P < 0.05). Vascular endothelial growth factor was significantly elevated in eyes of Category 2. An advancement of the maculopathy category was significantly associated with the need for multiple treatment of intravitreal bevacizumab (P < 0.05). In 12 eyes that required multiple intravitreal bevacizumab, the MCP-1 level was significantly elevated. CONCLUSION: The significant associations of mCNV in highly myopic eyes with elevated levels of vascular endothelial growth factor or inflammatory cytokines and maculopathy lesions strongly suggest an involvement of inflammation in the etiology of mCNVs.

Changes of TGF-ß2, MMP-2, and TIMP-2 levels in the vitreous of patients with high myopia.

PURPOSE: To investigate the concentrations of transforming growth factor (TGF)-ß2, matrix metalloproteinase (MMP)-2, and tissue inhibitor of metalloproteinase (TIMP)-2 in the vitreous of patients with high myopia. METHODS: Twenty-six patients with high myopia (HM) who received vitrectomy for macular retinoschisis or macular hole were enrolled in this prospective study. Twenty-six patients with idiopathic macular hole or macular epiretinal membrane were chosen as a control group. Vitreous samples were obtained during the vitrectomy surgery. The levels of TGF-ß2、MMP-2、TIMP-2 in the vitreous samples were measured by enzyme-linked immunosorbent assay. The MMP activity was determined by a fluorometric assay. RESULTS: There was no significant difference in the vitreous level of TGF-ß2 between HM (1.64 ± 0.38 ng/ml) and the control group (1.56 ± 0.32 ng/ml, p = 0.56). The vitreous levels of MMP-2 in HM (32.40 ± 14.90 ng/ml) were significantly higher than in the control group (21.42 ± 6.74 ng/ml, p < 0.01). The ratio of MMP-2/TIMP-2 was significantly elevated in the vitreous samples from HM (0.61 ± 0.19), compared to the control group (0.48 ± 0.11, p < 0.05). The MMP activity was also significantly elevated in the vitreous samples from HM (4,030.8 ± 1,257.3 FIU), compared to the control group (3,245.8 ± 835.6 FIU, p < 0.05). CONCLUSIONS: The elevated MMP/TIMP ratio and MMP activity may play a role in the pathogenesis of human high myopia. Large prospective studies are needed to further investigate the effect of MMPs in the pathogenesis of human high myopia.

A genome-wide association study reveals association between common variants in an intergenic region of 4q25 and high-grade myopia in the Chinese Han population.

High-grade myopia (HM) is highly heritable, and has a high prevalence in the Han Chinese population. We carried out a genome-wide association study involving 102 HM cases suffering from retinal degeneration, and 335 controls who were free from HM and fundus diseases. Significant single-nucleotide polymorphisms were replicated in two follow-up studies: stage I involved 2628 independent cases and 9485 controls, and stage II involved a further 263 cases and 586 HM-free controls. The results were combined in a meta-analysis. Cases and controls were drawn from the Chinese Han population. A locus in an intergenic region at 4q25, within MYP11 (4q22-q27, OMIM: 609994), was found to be associated with HM (rs10034228, P(meta) = 7.70 × 10(-13), allelic odds ratio = 0.81, 95% confidence interval 0.76-0.86). There are no known genes in the region but a number of expressed sequence tags (ESTs) have been located there, one of which (BI480957) has been reported to express in the native human retinal pigment epithelium. In addition, a predicted gene was identified in this region. The gene's predicted protein sequence is highly similar to tubulin, beta 8 and beta-tubulin 4Q. Several previous studies have shown that tubulin plays an important role in eye development. Our result is compatible with a previous linkage study in the Han Chinese population (mapping in MYP11, 4q22-q27), and provides a more accurate locus for HM. Although there is insufficient evidence to indicate that expressed EST and the predicted gene play an important role in developing HM, this region merits further study as a candidate for the disease.

[Amyloid-like fibrils forming and fibroblasts destruction in Tenon's capsule in progressive myopia as a result of pigment epithelium derived factor resistance to restricted proteolysis].

We have shown previously the presence of full length (50 kD) and truncated proteolytic form (45 kD) of pigment epithelium derived factor (PEDF) in the eye Tenon's capsule in progressive myopia. The full length PEDF is prevalent in myopia that correlates with breach in collagen fibrils forming. Immunohistochemical analysis of Tenon's capsule with polyclonal antibodies to PEDF revealed PEDF in control group being exclusively inside fibroblasts, whereas in myopia, PEDF was distributed extracellularly as halo around blasted fibroblasts. By means of atomic force microscopy and immunodot analysis with anti amyloid fibrils antibodies the ability was studied of recombinant PEDF fragments to form fibrils. Only full length PEDF was shown to form amyloid like fibril structures, but not the truncated form. Accumulation offibrils results in fibroblasts destruction and might be the cause of changes in biochemical and morphological structure of Tenon's capsule observed in myopia.

Increased Levels of DKK1 in Vitreous Fluid of Patients with Pathological Myopia and the Correlation between DKK1 Levels and Axial Length.

Purpose: Dickkopf 1 (DKK1) functions as a natural antagonist of the canonical Wnt/ß-catenin pathway. The purpose of this study was to examine the expression of DKK1 in vitreous samples of patients with pathological myopia, in order to search for possible correlations between DKK1 and axial length.Materials and Methods: The expression of DKK1 and other cytokines in vitreous samples of 44 non-myopic eyes, 42 eyes with low-to-moderate myopia, and 51 eyes with pathological myopia were examined using multiplex cytokine detection technology. Ophthalmologic characteristics, including axial length and subfoveal choroidal thickness, were clinically measured for further analysis.Results: The intravitreous levels of DKK1 (P < .0001) were markedly higher in the pathological myopia group than in the control group. There were no differences of DKK1 levels in different vitreoretinal conditions. Additionally, we found that the DKK1 levels were positively correlated with HGF (ß = 0.268, P = .032), and TIMP-3 (ß = 0.209, P = .047) levels, as well as with axial length (ß = 0.714, P < .0001) in the pathological myopia group.Conclusions: Elevated levels of DKK1 were found in the eyes with elongated axial length.

Crosstalk between EP2 and PPARα Modulates Hypoxic Signaling and Myopia Development in Guinea Pigs.

Purpose: Cyclic adenosine monophosphate (cAMP) and peroxisome proliferator-activated receptor alpha (PPARα) levels mediate extracellular matrix (ECM) changes by altering the levels of hypoxia-inducible factor 1-alpha (HIF-1α) in various tissues. We aimed to determine, in the sclera of guinea pigs, whether a prostanoid receptor (EP2)-linked cAMP modulation affects PPARα and HIF-1α signaling during myopia. Methods: Three-week-old guinea pigs (n = 20 in each group), were monocularly injected with either an EP2 agonist (butaprost 1 µmol/L/10 µmol/L), an antagonist (AH6809 10 µmol/L/30 µmol/L) or a vehicle solution for two weeks during normal ocular growth. Separate sets of animals received these injections and underwent form deprivation (FD) simultaneously. Refraction and axial length (AL) were measured at two weeks, followed by scleral tissue isolation for quantitative PCR (qPCR) analysis (n = 10) and cAMP detection (n = 10) using a radioimmunoassay. Results: Butaprost induced myopia development during normal ocular growth, with proportional increases in AL and cAMP levels. FD did not augment the magnitude of myopia or cAMP elevations in these agonist-injected eyes. AH6809 suppressed cAMP increases and myopia progression during FD, but had no effect in a normal visual environment. Of the diverse set of 27 genes related to cAMP, PPARα and HIF-1α signaling and ECM remodeling, butaprost differentially regulated 15 of them during myopia development. AH6809 injections during FD negated such differential gene expressions. Conclusion: EP2 agonism increased cAMP and HIF-1α signaling subsequent to declines in PPARα and RXR mRNA levels, which in turn decreased scleral fibrosis and promoted myopia. EP2 antagonism instead inhibited each of these responses. Our data suggest that EP2 suppression may sustain scleral ECM structure and inhibit myopia development.

Comparison of Femto-LASIK With Combined Accelerated Cross-linking to Femto-LASIK in High Myopic Eyes: A Prospective Randomized Trial.

PURPOSE: To evaluate the safety and efficacy of femtosecond (fs) laser-assisted in situ keratomileusis (LASIK) combined with accelerated corneal cross-linking (LASIK Xtra) compared to conventional fs-LASIK (convLASIK) in high myopic patients. DESIGN: Prospective, randomized, fellow-eye controlled clinical trial. METHODS: Setting: Department of Ophthalmology, Goethe University, Frankfurt/Germany. StudyPopulation: Twenty-six patients with high myopia and/or myopic astigmatism received randomized treatment with LASIK Xtra (30 mW/cm2, 90 seconds with continuous ultraviolet-A) in 1 eye and convLASIK in the other eye. MainOutcomeMeasures: Uncorrected distance visual acuity (UDVA), best spectacle-corrected VA (BSCVA), manifest refractive spherical equivalent (MRSE), endothelial cell count (ECC), and corneal thickness. RESULTS: The UDVA improved from 1.26 ± 0.13 logMAR preoperative to -0.02 ± 0.15logMAR in LASIK Xtra eyes and from 1.27 ± 0.12 logMAR to 0.01 ± 0.15 logMAR in the convLASIK eyes (P > .05). The MRSE changed from -7.35 ± 1.15 diopters (D) and -7.5 ± 1.12 D to -0.17 ± 0.43 D and -0.25 ± 0.46 D, respectively. There was no significant difference in outcomes between both groups during the 12 months follow-up except for the convLASIK eyes' showing slightly better BSCVA after 1 week (P < .05). ConvLASIK eyes revealed a nonsignificant trend toward myopic regression from 3 to 12 months postoperative with a change in MRSE of -0.15 D compared to -0.1 D in LASIK Xtra eyes. Topography showed stability of corneal curvature with no signs of keratectasia in both groups at 12 months. CONCLUSION: While apparently safe, LASIK Xtra showed no advantages over conventional LASIK. At 12 months, both groups showed no difference regarding UDVA and refractive stability, and no signs of keratectasia.