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.

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.

Pharmacotherapy of Myopic Choroidal Neovascularization.

BACKGROUND: Myopic choroidal neovascularization (CNV) is a common cause of central visual loss in patients with high myopia, and the most common form of CNV in younger individuals. Pharmacologic therapy is the current mainstay of treatment of these patients. METHODS: Review of pharmacological treatment options for myopic CNV, which primarily involves intravitreal administration of anti-vascular endothelial growth factor (anti-VEGF) agents. RESULTS: At this time, anti-VEGF therapy agents are the first-line therapy in these patients. Comparative trials have not identified any major differences in treatment outcomes between aflibercept, bevacizumab, and ranibizumab. Only ranibizumab is approved for this indication in the US. Best visual outcomes are associated with younger age, smaller lesion size, and absence of chorioretinal atrophy. CONCLUSION: Anti-VEGF therapy is generally very effective in the treatment of myopic CNV.

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.

A Novel Potentially Causative Variant of NDUFAF7 Revealed by Mutation Screening in a Chinese Family With Pathologic Myopia.

Purpose: Pathologic myopia described as myopia accompanied by severe deformation of the eye besides excessive elongation of eye, is usually a genetic heterogeneous disorder characterized by extreme, familial, early-onset vision loss. However, the exact pathogenesis of pathologic myopia remains unclear. In this study, we screened a Han Chinese family with pathologic myopia to identify the causative mutation and explore the possible pathogenic mechanism based on evaluation of the biological functions of the mutation. Methods: We identified the mutations in a family with pathologic myopia by single nucleotide polymorphism array combined with short tandem repeat microsatellite marker analysis and exome sequencing. Mutations were validated among family members by direct Sanger sequencing. The subcellular localization of the protein variant was investigated by immunofluorescence, and the stability of the mutant protein was determined by immunoblotting. Intracellular levels of adenosine triphosphate and reactive oxygen species and complex I activity were measured by traditional biochemical methods to determine the functional role of the disease-associated mutation. Results: The novel missense mutation: c.798C>G (p.Asp266Glu) in NDUFAF7, cosegregated with the disease and the resulting amino acid substitution affected a highly conserved residue in its protein. The mutation D266E in NDUFAF7 impaired complex I activity, which resulted in decreased ATP levels in cultured cells. Conclusions: We propose that the heterozygous mutation (c.798C>G) in NDUFAF7 may contribute to the pathogenesis of pathologic myopia, possibly by interfering with the phototransduction cascade. Mitochondrial dysfunction during eye development may lead to pathologic myopia.

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.

Assessing oxygen saturation in retinal vessels in high myopia patients pre- and post-implantable collamer lens implantation surgery.

PURPOSE: To determine whether posterior chamber phakic implantable collamer lens (ICL) surgery in high myopia patients impedes oxygen saturation of retinal vessels. METHODS: Mean oxygen saturation and diameter in retinal blood vessels were measured before and after ICL implantation surgery to correct high myopia refractive errors (i.e. -6.00 to -20.25 dioptres [D]), using an Oxymap T1 retinal oximeter. RESULTS: In 17 eyes of 17 patients, the Oxymap T1 retinal oximeter detected a small but significant decrease in oxygen saturation of retinal venules, 1-week postoperatively (compared to preoperative measurements). Moreover, at 1 week after ICL implantation, the diameter of patient retinal vessels had consistently contracted, compared to preoperative measurements. By 1 month after ICL surgery, however, both the oxygen saturation and retinal vessel diameter had returned to preoperative levels. Otherwise, no statistically significant difference in oxygen saturation and diameter of retinal arterioles was found when comparing their measurements before and 1 week after implantation. CONCLUSION: Stable levels of oxygen saturation in retinal vessels, as detected by the Oxymap T1 oximeter, show ICL implantation would not leave lasting impact or adverse effects to retina oxygen saturation in high myopia patients.

Visual Outcomes After SMILE, LASEK, and LASEK Combined With Corneal Collagen Cross-Linking for High Myopic Correction.

PURPOSE: To compare the visual and refractive outcomes of small-incision lenticule extraction (SMILE), laser-assisted subepithelial keratomileusis (LASEK), and LASEK combined with corneal collagen cross-linking (LASEK-CXL) surgery for high-degree myopia. METHODS: Medical records of patients with spherical equivalent (SE) greater than -6.00 diopters (D) treated with SMILE, LASEK, and LASEK-CXL were reviewed. Uncorrected distance visual acuity (UCVA), SE, and corneal haze were followed up in the 3 groups for 6 months. RESULTS: The SMILE group included 69 eyes, the LASEK group included 61 eyes, and the LASEK-CXL group included 40 eyes. At 6 months postoperatively, there were no statistically significant differences in UCVA between the SMILE, LASEK, and LASEK-CXL groups (logMAR 0.00 ± 0.00, 0.01 ± 0.08, and 0.01 ± 0.08, respectively, P = 0.69). The averages of the absolute value of SE were 0.34 ± 0.25 D, 0.50 ± 0.36 D, and 0.42 ± 0.34 D in the SMILE, LASEK, and LASEK-CXL groups, respectively (P = 0.04). The percentages of the patients with a postoperative residual refractive error within ±0.50 D were 84% in the SMILE group, 65% in the LASEK group, and 76% in the LASEK-CXL group. The percentages of the patients with greater than 20/25 postoperative UCVA were 100%, 91%, and 95%, respectively. SMILE produced no postoperative corneal haze. However, 18% of patients treated with LASEK and 25% of those treated with LASEK-CXL had corneal haze at 6 months postoperatively. CONCLUSIONS: SMILE, LASEK, and LASEK-CXL surgery appear to be safe and effective for high-degree myopic correction. However, the SMILE group had no haze and fewer induction of some higher-order aberrations compared with the LASEK and LASEK-CXL groups.

Scleral Cross-Linking Using Riboflavin UVA Irradiation for the Prevention of Myopia Progression in a Guinea Pig Model: Blocked Axial Extension and Altered Scleral Microstructure.

PURPOSE: To develop methods of collagen cross-linking (CXL) in the sclera for the treatment of progressive myopia and to investigate the biomechanical and histological changes that occur in as a result. METHODS: Twenty 14-day-old guinea pigs were divided into 3 groups: the cross-linking group (CL, n = 8), non cross-linking group (NCL, n = 8), and control group (n = 4). The scleras of the right eyes of the guinea pigs in the CL group were surgically exposed and riboflavin was dropped onto the irradiation zone for 20 seconds prior to ultraviolet-A (UVA) irradiation. The same procedure was conducted on the NCL group but without UVA irradiation. No procedure was conducted on the control group. The right eyes of the guinea pigs in the CL and NCL groups were then fitted with -10.00DS optics for six weeks. Retinoscopy and the axial lengths (AXL) were measured at baseline, and at the second, fourth and sixth weeks post-treatment in all three groups. All animal subjects were euthanized after the sixth week and then biomechanical and histopathological examinations of the scleras were conducted. RESULTS: The mean AXL of the NCL group was longer than both the control and CL groups at six weeks (P = 0.001). The mean refractive error in the NCL group was statistically significantly more negative than both the control and the CL groups at six weeks (P = 0.001). The scleral collagen fiber arrangements of the CL and control groups were denser and more regularly distributed than the NCL group. Ultimate stress of the sclera was lowest in the NCL group, followed by the CL then the control group (P<0.05). Ultimate strain (%) of the sclera was lowest in the CL group followed by the NCL and then the control group (P<0.05). CONCLUSION: Our study demonstrates that scleral CXL using riboflavin UVA irradiation effectively prevents the progression of myopia by increasing scleral biomechanical strength in a guinea pig model.

Elevated TGF-ß2 level in aqueous humor of cataract patients with high myopia: Potential risk factor for capsule contraction syndrome.

PURPOSE: To evaluate the level of transforming growth factor-ß2 (TGF-ß2) in the aqueous humor of highly myopic cataract patients and its correlation with capsule contraction syndrome. SETTING: Eye and ENT Hospital of Fudan University, Shanghai, China. DESIGN: Prospective comparative case series. METHODS: The highly myopic cataract patients were divided into the following 2 groups according to the Lens Opacity Classification System III: nuclear color (NC) 2 to 3 and NC 5 to 6. Aqueous humor TGF-ß2 concentrations were assayed in the highly myopic cataract and age-related cataract groups. The TGF-ß2, TGF-ßRII (the type II receptor for TGF-ß2), and α-smooth muscle actin (α-SMA) expressions in lens epithelial cells (LECs) were detected by real-time polymerase chain reaction and immunofluorescent staining. RESULTS: The study comprised 40 highly myopic cataract patients (40 eyes) and 20 patients (20 eyes) with age-related cataract as the control group. Compared with the control group, the highly myopic cataract group had significantly higher TGF-ß2 concentration in the aqueous humor and increased TGF-ßRII expression in LECs, especially in NC 5 to 6 cases. Expression of α-SMA was barely detectable in both groups. CONCLUSION: In highly myopic cataract patients, especially those with dark nuclei, elevated aqueous humor TGF-ß2 levels and the upregulated TGF-ßRII expression in LECs might contribute to the pathogenesis of capsule contraction syndrome through transdifferentiation of LECs into myofibroblasts. FINANCIAL DISCLOSURE: None of the authors has a financial or proprietary interest in any material or method mentioned.

Effect of a Single Nucleotide Polymorphism in the LAMA1 Promoter Region on Transcriptional Activity: Implication for Pathological Myopia.

PURPOSE: To elucidate the role of the protein coding laminin α1 (LAMA1) gene in pathological myopia (PM) at the transcriptional level. To achieve this, the binding affinity of single nucleotide polymorphism (SNP) rs2089760-located on the LAMA1 promoter gene-to human fetal scleral fibroblast (HFSF) nucleoprotein was investigated and its effect on LAMA1 transcriptional initiation activity was analyzed. METHODS: Binding interactions of the HFSF nucleoprotein and biotin-labeled SNP rs2089760 probe were investigated by amplifying the LAMA1 promoter gene and performing overlap extension polymerase chain reaction (PCR) to obtain the G/A mutation of LAMA1 SNP rs2089760. Recombinant adenovirus vectors, Ad5f11p-pLAMA1SNPa-Luc2, Ad5f11p-pLAMA1SNPg-Luc2, and Ad5f11p-CMV-RLuc, were constructed. Fluorescence intensity ratios of firefly luciferase (FLuc) and renilla luciferase (RLuc) vectors were measured 48 h after HFSF infection. RESULTS: Both specific and mutant probes banded precisely with HFSF nucleoprotein. The intensity value of the mutant probe was significantly lower than that of the specific probe (p < 0.05). HFSFs were successfully infected by the recombinant adenoviruses. The FLuc/RLuc fluorescence intensity ratio of Ad5f11p-pLAMA1SNPa-Luc2 (0.0238 ± 0.0009) was significantly lower than that of Ad5f11p-pLAMA1SNPg-Luc2 (0.0281 ± 0.0015) (p < 0.05). CONCLUSIONS: It is highly likely that SNP rs2089760 in the LAMA1 promoter region is located at the transcription factor binding site. The SNP rs2089760 G > A mutation reduces transcription factor binding ability and transcriptional initiation activity, and negatively regulates gene transcription of LAMA1. We suggest that LAMA1 SNP rs2089760 plays an important role in the development of PM.

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.

Anti-VEGF treatment for myopic choroid neovascularization: from molecular characterization to update on clinical application.

Choroidal neovascularization (CNV) secondary to pathologic myopia has a very high incidence in global, especially in Asian, populations. It is a common cause of irreversible central vision loss, and severely affects the quality of life in the patients with pathologic myopia. The traditional therapeutic modalities for CNV secondary to pathologic myopia include thermal laser photocoagulation, surgical management, transpupillary thermotherapy, and photodynamic therapy with verteporfin. However, the long-term outcomes of these modalities are disappointing. Recently, intravitreal administration of anti-VEGF biological agents, including bevacizumab, ranibizumab, pegaptanib, aflibercept, and conbercept, has demonstrated promising outcomes for this ocular disease. The anti-VEGF regimens are more effective on improving visual acuity, reducing central fundus thickness and central retina thickness than the traditional modalities. These anti-VEGF agents thus hold the potential to become the first-line medicine for treatment of CNV secondary to pathologic myopia. This review follows the trend of "from bench to bedside", initially discussing the pathogenesis of myopic CNV, delineating the molecular structures and mechanisms of action of the currently available anti-VEGF drugs, and then systematically comparing the up to date clinical applications as well as the efficacy and safety of the anti-VEGF drugs to the CNV secondary to pathologic myopia.

Effect of intravitreal ranibizumab injections on aqueous humour concentrations of vascular endothelial growth factor and pigment epithelium-derived factor in patients with myopic choroidal neovascularisation.

AIMS: To investigate aqueous humour changes in vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF) levels in patients with choroidal neovascularisation (CNV) secondary to pathological myopia (mCNV) before and after intravitreal ranibizumab injection (IVR). METHODS: This was a prospective, case-control study investigating aqueous levels of VEGF and PEDF in eyes with mCNV treated with IVR. RESULTS: Mean VEGF and PEDF levels in the aqueous humour of control patients were 25.7±4.9 pg/mL and 12.6±3.5 ng/mL, respectively. Lower levels of both VEGF (19.5±5.4 pg/mL) and PEDF (4.7±2.2 ng/mL) were found in patients with mCNV before IVR. After IVR, aqueous VEGF levels significantly reduced to 6.5±2.7 pg/mL, while PEDF levels significantly increased to 35.8±11.4 ng/mL. VEGF and PEDF levels significantly correlated with each other, and with best-corrected visual acuity and central retinal thickness. CONCLUSIONS: The VEGF and PEDF levels in aqueous humour were significantly lower in the myopic group than in controls. Moreover, IVR resulted in reduced VEGF and increased PEDF levels in patients with mCNV. In mCNV, neovascularisation is associated with inappropriate VEGF and PEDF expression. A balance between VEGF and PEDF is crucial to prevent CNV development. TRIAL REGISTRATION NUMBER: NCT02175940.

Correlation of macular choroidal thickness with concentrations of aqueous vascular endothelial growth factor in high myopia.

PURPOSE: To investigate the association of both aqueous and serum vascular endothelial growth factor (VEGF) levels and macular choroidal thickness in high myopia. MATERIALS AND METHODS: VEGF concentrations were measured in aqueous and serum samples via enzyme-linked immunosorbent assay (ELISA) and compared between high myopia (n = 36 eyes, 36 patients) and normal control (n = 42 eyes, 42 patients) eyes. Macular choroidal thickness, the distance from the retinal pigment epithelium (RPE) to the scleral interface, was determined via enhanced depth-imaging optical coherence tomography (EDI-OCT). Axial length was measured using the intraocular (IOL) lens Master. RESULTS: Aqueous levels of VEGF from high myopia patients were significantly lower compared with those from control persons (61.4 ± 27.6 versus 122.6 ± 52.4 pg/ml; p < 0.001), respectively. Macular choroidal thickness of high myopia patients was significantly lower compared with that of control persons (111.1 ± 45.0 versus 230.6 ± 81.8 µm; p < 0.001), respectively. Aqueous levels of VEGF were significantly associated with both macular choroidal thickness (R(2)= 0.641; p < 0.001) and axial length (R(2)= 0.679; p < 0.001) in high myopia patients. In addition, there was a significantly negative correlation between macular choroidal thickness and axial length (R(2)= 0.69; p < 0.001). However, no correlation between serum VEGF and either macular choroidal thickness or axial length was detected in high myopia patients (R(2)= 0.009; p = 0.59; R(2)= 0.00002; p = 0.981). CONCLUSIONS: Macular choroidal thickness was significantly correlated with aqueous, but not serum, levels of VEGF in highly myopic eyes. Macular choroidal thickness may be of predictive value for identifying aqueous VEGF levels in high myopia patients and may, thus, be a useful prognostic modality.

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.

Aqueous humor levels of vascular endothelial growth factor and pigment epithelium-derived factor in polypoidal choroidal vasculopathy and choroidal neovascularization.

PURPOSE: To determine the aqueous levels of vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF) in patients with active polypoidal choroidal vasculopathy (PCV) and choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD) and pathologic myopia. DESIGN: Prospective, comparative control study. METHODS: Aqueous humors were collected from 32 eyes of 32 patients for either active PCV or CNV. Among them, 11 eyes had active and symptomatic PCV, 12 eyes had active CNV secondary to AMD, and nine eyes had active CNV of pathologic myopia. Levels of VEGF and PEDF were determined by commercially available enzyme-linked immunosorbent assay kits. A group of 10 aqueous samples from 10 patients who underwent cataract surgery without other ocular or systemic diseases comprised the controls. RESULTS: VEGF concentrations in aqueous humor were markedly increased in patients with PCV, CNV of AMD, and CNV of myopia when compared with the controls (analysis of variance [ANOVA], P < .001). VEGF levels in eyes with PCV were, however, significantly lower than those of exudative AMD (P = .045). The PEDF levels were also significantly different among the groups (ANOVA, P = .001), and we observed increased levels in PCV, CNV of AMD, and CNV of myopia. CONCLUSIONS: VEGF and PEDF factors were coexpressed and increased with positive correlation in aqueous humor of eyes with active PCV. The different levels of both factors in eyes of PCV and AMD might suggest distinct clinical entities or different angiogenesis courses between PCV and AMD.

Low levels of pigment epithelium-derived factor in highly myopic eyes with chorioretinal atrophy.

PURPOSE: To determine the concentration of pigment epithelium-derived factor (PEDF) in the aqueous humor of highly myopic eyes. DESIGN: Observational case series. METHODS: The PEDF concentration in the aqueous humor of 23 eyes of 17 patients with high myopia (axial length >26 mm) who underwent cataract surgery was measured by enzyme-linked immunosorbent assay. RESULTS: The mean concentration of PEDF in eyes with high myopia (0.54 +/- 0.12 microg/ml) was significantly lower than that in control eyes (0.86 +/- 0.04 microg/ml, P = .0022). The PEDF level in myopic eyes with chorioretinal atrophy (0.32 +/- 0.05 microg/ml) was lower than that in myopic eyes without chorioretinal atrophy (0.71 +/- 0.12 microg/ml; P = .041) and control eyes (P = .0003). CONCLUSIONS: The significantly lower concentration of PEDF in eyes with chorioretinal atrophy-associated high myopia probably resulted from degeneration of the retinal pigment epithelial cells and/or the retinal ganglion cells that are the main sources of PEDF in the eye.