Genome-wide association meta-analysis highlights light-induced signaling as a driver for refractive error.

Refractive errors, including myopia, are the most frequent eye disorders worldwide and an increasingly common cause of blindness. This genome-wide association meta-analysis in 160,420 participants and replication in 95,505 participants increased the number of established independent signals from 37 to 161 and showed high genetic correlation between Europeans and Asians (>0.78). Expression experiments and comprehensive in silico analyses identified retinal cell physiology and light processing as prominent mechanisms, and also identified functional contributions to refractive-error development in all cell types of the neurosensory retina, retinal pigment epithelium, vascular endothelium and extracellular matrix. Newly identified genes implicate novel mechanisms such as rod-and-cone bipolar synaptic neurotransmission, anterior-segment morphology and angiogenesis. Thirty-one loci resided in or near regions transcribing small RNAs, thus suggesting a role for post-transcriptional regulation. Our results support the notion that refractive errors are caused by a light-dependent retina-to-sclera signaling cascade and delineate potential pathobiological molecular drivers.

When do myopia genes have their effect? Comparison of genetic risks between children and adults.

Previous studies have identified many genetic loci for refractive error and myopia. We aimed to investigate the effect of these loci on ocular biometry as a function of age in children, adolescents, and adults. The study population consisted of three age groups identified from the international CREAM consortium: 5,490 individuals aged <10 years; 5,000 aged 10-25 years; and 16,274 aged >25 years. All participants had undergone standard ophthalmic examination including measurements of axial length (AL) and corneal radius (CR). We examined the lead SNP at all 39 currently known genetic loci for refractive error identified from genome-wide association studies (GWAS), as well as a combined genetic risk score (GRS). The beta coefficient for association between SNP genotype or GRS versus AL/CR was compared across the three age groups, adjusting for age, sex, and principal components. Analyses were Bonferroni-corrected. In the age group <10 years, three loci (GJD2, CHRNG, ZIC2) were associated with AL/CR. In the age group 10-25 years, four loci (BMP2, KCNQ5, A2BP1, CACNA1D) were associated; and in adults 20 loci were associated. Association with GRS increased with age; ß = 0.0016 per risk allele (P = 2 × 10-8 ) in <10 years, 0.0033 (P = 5 × 10-15 ) in 10- to 25-year-olds, and 0.0048 (P = 1 × 10-72 ) in adults. Genes with strongest effects (LAMA2, GJD2) had an early effect that increased with age. Our results provide insights on the age span during which myopia genes exert their effect. These insights form the basis for understanding the mechanisms underlying high and pathological myopia.

Genome-wide association study for refractive astigmatism reveals genetic co-determination with spherical equivalent refractive error: the CREAM consortium.

To identify genetic variants associated with refractive astigmatism in the general population, meta-analyses of genome-wide association studies were performed for: White Europeans aged at least 25 years (20 cohorts, N = 31,968); Asian subjects aged at least 25 years (7 cohorts, N = 9,295); White Europeans aged <25 years (4 cohorts, N = 5,640); and all independent individuals from the above three samples combined with a sample of Chinese subjects aged <25 years (N = 45,931). Participants were classified as cases with refractive astigmatism if the average cylinder power in their two eyes was at least 1.00 diopter and as controls otherwise. Genome-wide association analysis was carried out for each cohort separately using logistic regression. Meta-analysis was conducted using a fixed effects model. In the older European group the most strongly associated marker was downstream of the neurexin-1 (NRXN1) gene (rs1401327, P = 3.92E-8). No other region reached genome-wide significance, and association signals were lower for the younger European group and Asian group. In the meta-analysis of all cohorts, no marker reached genome-wide significance: The most strongly associated regions were, NRXN1 (rs1401327, P = 2.93E-07), TOX (rs7823467, P = 3.47E-07) and LINC00340 (rs12212674, P = 1.49E-06). For 34 markers identified in prior GWAS for spherical equivalent refractive error, the beta coefficients for genotype versus spherical equivalent, and genotype versus refractive astigmatism, were highly correlated (r = -0.59, P = 2.10E-04). This work revealed no consistent or strong genetic signals for refractive astigmatism; however, the TOX gene region previously identified in GWAS for spherical equivalent refractive error was the second most strongly associated region. Analysis of additional markers provided evidence supporting widespread genetic co-susceptibility for spherical and astigmatic refractive errors.

Retinal nerve fibre layer thickness measurements after successful retinal detachment repair with silicone oil endotamponade.

AIMS: To measure peripapillary retinal nerve fibre layer thickness (RNFL) by using spectral domain optical coherence tomography (OCT) in patients who underwent successful retinal detachment repair with silicone oil tamponade. METHODS: Sixty patients treated with pars plana vitrectomy and silicone oil tamponade for retinal detachment were prospectively enrolled in a study. Peripapillary RNFL thickness was measured with a Cirrus HD-OCT at 7, 30, 90 and 180 days postoperatively, using an Optic Disc Cube 200×200 protocol. The fellow eye of each study patient served as a control. Median peripapillary RNFL thickness in silicone oil filled eyes was compared with control eyes. RESULTS: The median RNFL thickness in the group of vitrectomised eyes was significantly higher compared with control eyes at every visit. The analysis of variance showed that the median thickness in vitrectomised eyes differed between visits (F=4,3023; p=0.006). There was no time-related trend for RNFL thickness in this group. The analysis of variance of RNFL thickness in the fellow, unoperated eyes showed no difference between visits (F=2,3426; p=0.075). CONCLUSIONS: In patients with silicone oil tamponade, peripapillary RNFL was significantly thicker in comparison with fellow unoperated eyes over a 6-month period. TRIAL REGISTRATION NUMBER: NCT 01255306.

Genome-wide meta-analysis of myopia and hyperopia provides evidence for replication of 11 loci.

Refractive error (RE) is a complex, multifactorial disorder characterized by a mismatch between the optical power of the eye and its axial length that causes object images to be focused off the retina. The two major subtypes of RE are myopia (nearsightedness) and hyperopia (farsightedness), which represent opposite ends of the distribution of the quantitative measure of spherical refraction. We performed a fixed effects meta-analysis of genome-wide association results of myopia and hyperopia from 9 studies of European-derived populations: AREDS, KORA, FES, OGP-Talana, MESA, RSI, RSII, RSIII and ERF. One genome-wide significant region was observed for myopia, corresponding to a previously identified myopia locus on 8q12 (p = 1.25×10(-8)), which has been reported by Kiefer et al. as significantly associated with myopia age at onset and Verhoeven et al. as significantly associated to mean spherical-equivalent (MSE) refractive error. We observed two genome-wide significant associations with hyperopia. These regions overlapped with loci on 15q14 (minimum p value = 9.11×10(-11)) and 8q12 (minimum p value 1.82×10(-11)) previously reported for MSE and myopia age at onset. We also used an intermarker linkage- disequilibrium-based method for calculating the effective number of tests in targeted regional replication analyses. We analyzed myopia (which represents the closest phenotype in our data to the one used by Kiefer et al.) and showed replication of 10 additional loci associated with myopia previously reported by Kiefer et al. This is the first replication of these loci using myopia as the trait under analysis. "Replication-level" association was also seen between hyperopia and 12 of Kiefer et al.'s published loci. For the loci that show evidence of association to both myopia and hyperopia, the estimated effect of the risk alleles were in opposite directions for the two traits. This suggests that these loci are important contributors to variation of refractive error across the distribution.

Genetic influences on plasma CFH and CFHR1 concentrations and their role in susceptibility to age-related macular degeneration.

It is a longstanding puzzle why non-coding variants in the complement factor H (CFH) gene are more strongly associated with age-related macular degeneration (AMD) than functional coding variants that directly influence the alternative complement pathway. The situation is complicated by tight genetic associations across the region, including the adjacent CFH-related genes CFHR3 and CFHR1, which may themselves influence the alternative complement pathway and are contained within a common deletion (CNP147) which is associated with protection against AMD. It is unclear whether this association is mediated through a protective effect of low plasma CFHR1 concentrations, high plasma CFH or both. We examined the triangular relationships of CFH/CFHR3/CFHR1 genotype, plasma CFH or CFHR1 concentrations and AMD susceptibility in combined case-control (1256 cases, 1020 controls) and cross-sectional population (n = 1004) studies and carried out genome-wide association studies of plasma CFH and CFHR1 concentrations. A non-coding CFH SNP (rs6677604) and the CNP147 deletion were strongly correlated both with each other and with plasma CFH and CFHR1 concentrations. The plasma CFH-raising rs6677604 allele and raised plasma CFH concentration were each associated with AMD protection. In contrast, the protective association of the CNP147 deletion with AMD was not mediated by low plasma CFHR1, since AMD-free controls showed increased plasma CFHR1 compared with cases, but it may be mediated by the association of CNP147 with raised plasma CFH concentration. The results are most consistent with a regulatory locus within a 32 kb region of the CFH gene, with a major effect on plasma CFH concentration and AMD susceptibility.

Genome-wide association study identifies genetic risk underlying primary rhegmatogenous retinal detachment.

Rhegmatogenous retinal detachment (RRD) is an important cause of vision loss and can potentially lead to blindness. The underlying pathogenesis is complex and incompletely understood. We applied a two-stage genetic association discovery phase followed by a replication phase in a combined total of 2833 RRD cases and 7871 controls. The discovery phase involved a genome-wide association scan of 867 affected individuals and 1953 controls from Scotland, followed by genotyping and testing 4347 highest ranking or candidate single nucleotide polymorphisms (SNPs) in independent sets of cases (1000) and controls (2912) of Dutch and British origin. None of the SNPs selected reached a Bonferroni-corrected threshold for significance (P < 1.27 × 10(-7)). The strongest association, for rs12960119 (P = 1.58 × 10(-7)) located within an intron of the SS18 gene. Further testing was carried out in independent case-control series from London (846 cases) and Croatia (120 cases). The combined meta-analysis identified one association reaching genome-wide significance for rs267738 (OR = 1.29, P = 2.11 × 10(-8)), a missense coding SNP and eQTL for CERS2 encoding the protein ceramide synthase 2. Several of the top signals showing suggestive significance in the combined meta-analysis encompassed genes with a documented role in cell adhesion or migration, including SS18, TIAM1, TSTA3 and LDB2, which warrant further investigation. This first genetic association study of RRD supports a polygenic component underlying RRD risk since 27.4% of the underlying RRD liability could be explained by the collective additive effects of the genotyped SNP from the discovery genome-wide scan.

New loci associated with central cornea thickness include COL5A1, AKAP13 and AVGR8.

Central corneal thickness (CCT) is a highly heritable trait, which has been proposed to influence disorders of the anterior segment of the eye. A genome-wide association study (GWAS) of CCT was performed in 2269 individuals from three Croatian and one Scottish population. In the discovery set (1445 individuals), two genome-wide significant associations were identified for single nucleotide polymorphisms rs12447690 (ß = 0.23 SD, P = 4.4 × 10(-9)) and rs1536482 (ß = 0.22 SD, P = 7.1 × 10(-8)) for which the closest candidate genes (although ≥90 kb away) were zinc finger 469 (ZNF469) on 16q24.2 and collagen 5 alpha 1 (COL5A1) on 9q34.2, respectively. Only the ZNF469 association was confirmed in our replication set (824 individuals, P = 8.0 × 10(-4)) but COL5A1 remained a suggestive association in the combined sample (ß = 0.16 SD, P = 1.1 × 10(-6)). Following a larger meta-analysis including recently published CCT GWAS summary data, COL5A1 was genome-wide significant (ß = 0.13 SD, P = 5.1 × 10(-8)), together with two additional novel loci. The second new locus (defined by rs1034200) was 5 kb from the AVGR8 gene, encoding a putative transcription factor with typical ZNF and KRAB domains, in chromosomal region 13q12.11 (ß = 0.14 SD, P = 3.5 × 10(-9)). The third new locus (rs6496932), on 15q25.3 (ß = 0.13, P = 1.4 × 10(-8)), was within a wide linkage disequilibrium block extending into the 5' end of the AKAP13 gene, encoding a scaffold protein concerned with signal transduction from the cell surface. These associations offer mechanistic insights into the regulation of CCT and offer new candidate genes for susceptibility to common disorders in which CCT has been implicated, including primary open-angle glaucoma and keratoconus.

Heritabilities of ocular biometrical traits in two croatian isolates with extended pedigrees.

PURPOSE: To assess the effects of body stature and years of education, in addition to age and sex, on six oculometric traits and to estimate the heritabilities of these quantitative traits in two Croatian cross-population studies. METHODS: Adult subjects living on the two Croatian islands of Vis and Korcula were recruited for a large epidemiologic and genetic study that included eye biometry, keratometry, and autorefraction. Effects and heritabilities were estimated by using general linear mixed models for axial length (AL), anterior chamber depth (ACD), corneal curvature (CC), corneal thickness (CT), lens thickness (LT), and spherical equivalent refraction (SER). Both cohorts were genotyped with dense SNP arrays, allowing the use of kinship coefficients derived from genotypic data (realized kinship) rather than from pedigree information (expected kinship). RESULTS: Across cohorts, body mass index (BMI) did not consistently influence any of the ocular traits adjusted for age and/or sex, whereas height and years in education (YrEd) did, explaining up to an additional 5% of the variance (in CC). CT was the trait least influenced by covariates. Estimated heritabilities in Vis and Korcula, respectively, were 84% and 52% for CC, 75% and 71% for CT, 37% and 32% for LT, 59% and 45% for ACD, 37% and 74% for AL, and 0% and 17% for SER. CONCLUSIONS: While heritabilities of CT and CC seemed uniformly high across studies of Caucasian datasets, estimates for SER varied widely and were at the lower end of the spectrum of published observations in our study.

Common variant in myocilin gene is associated with high myopia in isolated population of Korcula Island, Croatia.

AIM: To study the association between genetic variants in myocilin and collagen type I alpha 1 genes and high myopia in an isolated island population. METHODS: A total of 944 examinees from the genetic epidemiology study conducted on the island of Korcula, Croatia, were included in the study. We selected 2 short nucleotide polymorphisms (SNP) available in our genome-wide scan set of SNPs that were previously associated with high myopia and used them to replicate previous claims of possible association. RESULTS: Nineteen cases of high myopia, defined as the refraction of

Genome-wide association study of biochemical traits in Korcula Island, Croatia.

AIM: To identify genetic variants underlying biochemical traits--total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides, uric acid, albumin, and fibrinogen, in a genome-wide association study in an isolated population where rare variants of larger effect may be more easily identified. METHODS: The study included 944 adult inhabitants of the island of Korcula, as a part of larger DNA-based genetic epidemiological study in 2007. Biochemical measurements were performed in a single laboratory with stringent internal and external quality control procedures. Examinees were genotyped using Human Hap370CNV chip by Illumina, with a genome-wide scan containing 346027 single nucleotide polymorphisms (SNP). RESULTS: A total of 31 SNPs were associated with 7 investigated traits at the level of P<1.00 x 10(-5). Nine of SNPs implicated the role of SLC2A9 in uric acid regulation (P=4.10 x 10(-6)-2.58 x 10(-12)), as previously found in other populations. All 22 remaining associations fell into the P=1.00 x 10(-5)-1.00 x 10(-6) significance range. One of them replicated the association between cholesteryl ester transfer protein (CETP) and HDL, and 7 associations were more than 100 kilobases away from the closest known gene. Nearby SNPs, rs4767631 and rs10444502, in gene kinase suppressor of ras 2 (KSR2) on chromosome 12 were associated with LDL cholesterol levels, and rs10444502 in the same gene with total cholesterol levels. Similarly, rs2839619 in gene PBX/knotted 1 homeobox 1 (PKNOX1) on chromosome 21 was associated with total and LDL cholesterol levels. The remaining 9 findings implied possible associations between phosphatidylethanolamine N-methyltransferase (PEMT) gene and total cholesterol; USP46, RAP1GDS1, and ZCCHC16 genes and triglycerides; BCAT1 and SLC14A2 genes and albumin; and NR3C2, GRIK2, and PCSK2 genes and fibrinogen. CONCLUSION: Although this study was underpowered for most of the reported associations to reach formal threshold of genome-wide significance under the assumption of independent multiple testing, replications of previous findings and consistency of association between the identified variants and more than one studied trait make such findings interesting for further functional follow-up studies. Changed allele frequencies in isolate population may contribute to identifying variants that would not be easily identified in much larger samples in outbred populations.

[Ophthalmological causes of headache]. / Okularni uzroci glavobolje.

Ophthalmologic causes of headache represent a very complex and extensive problem, and very often differential diagnostic problem too. Many various reasons of headache can be caused by ophthalmologic diseases like those of anterior and posterior eye segments, acute and subacute angle closed glaucoma and orbital diseases. Headache can be caused by no or poor correction of the refraction anomalies. Ophthalmologic causes of headache are quite frequently connected with conditions that affect other body systems apart from the eyes, nervous and/or vascular system in particular. Although ophthalmologic examination very provides the clue in patients with headache, the diagnostic and therapeutic approach to the problem has to be interdisciplinary.

Intravitreal bevacizumab for neovascular glaucoma.

The aim of the study was to assess short-term efficacy of intravitreal bevacizumab in a series of patients with neovascular glaucoma. Eleven patients with neovascular glaucoma and symptomatic elevation of intraocular pressure were treated with 1.25 mg/0.1 mL of bevacizumab. In three patients, intravitreal bevacizumab was administered preoperatively, one day before pars plana vitrectomy. Additional therapy was only performed if topical medication failed to result in satisfactory control of intraocular pressure. Patients were followed-up for a minimum of 8 weeks. In all study patients, intravitreal application of bevacizumab resulted in marked regression of iris neovascularization within the first three postoperative days. Appropriate control of intraocular pressure was achieved in seven patients, whereas four patients required additional therapy for intraocular pressure regulation. No side effects of intravitreal bevacizumab were recorded. Thus, intravitreal bevacizumab seems to be a potent adjunct in the management of neovascular glaucoma. Additional studies of bevacizumab long-term safety and efficacy are warranted.

[Correlation of photodynamic therapy outcome with choroidal neovascular membrane size]. / Procjena uspjesnosti fotodinamske terapije s obzirom na velicinu korioidalnih neovaskularizacija.

AIM: To show the results of photodynamic therapy according to the size of choroidal neovascular membrane size. PATIENTS AND METHODS: A retrospective analysis included 94 patients undergoing photodynamic therapy at University Department of Ophthalmology, Sestre MilosrdniceUniversity Hospital from 2001 till 2005. There were 61 patients with age related macular degeneration (AMD) and 33 patients with high myopia. All patients had a predominantly classic choroidal neovascular membrane. Patients were divided into two subgroups according to the lesion size. The first subgroup included patients with a lesion equal to or less than one disc diameter, and the second subgroup had a lesion greater than one disc diameter. All patients were followed up for a minimum of 3 months. RESULTS: In the group of patients with AMD statistical analysis showed no significant difference in total closure and decrease in the size of choroid neovascularization (CNV) between the two subgroups. In the group of patients with high myopia a statistically significant difference was found in total closure and decrease in the size of CNV between patients with lesions smaller or equal to one disc diameter and those with lesions greater than one disc diameter. The former group also had better visual outcome. CONCLUSION: The size of CNV was not a prognostic factor in patients with AMD. In patients with high myopia, better outcome was recorded in the subgroup with CNV smaller or equal to one disc diameter.

[Pars plana vitrectomy and intravitreal triamcinolone for chronic pseudophakic cystoid macular edema]. / Pars plana vitrektomija kod kronicnog pseudofaknog cistoidnog makularnog edema.

AIM: To report on the results of pars plana vitrectomy and intravitreal triamcinolone in patients with chronic pseudophakic cystoid macular edema unresponsive to medical treatment. PATIENTS AND METHODS: A retrospective analysis of 9 eyes in 9 patients with chronic pseudophakic cystoid macular edema was performed. All patients had cystoid macular edema confirmed on fluorescein angiography, and were unresponsive to medical treatment. In all patients pars plana vitrectomy and intravitreal application of 4 mg of triamcinolone was performed. In one patient with vitreous prolapse into the anterior chamber, anterior vitrectomy was also required. RESULTS: The mean interval between cataract surgery and vitrectomy was 16.28 +/- 2.1 months. The mean preoperative best corrected visual acuity was 0.1 +/- 0.11, and the mean final best corrected visual acuity 0.25 +/- 0.24, after a mean follow up of 6.6 +/- 3.5 months. In all 9 eyes there was a marked reduction of cystoid macular edema, as verified on fluorescein angiography. Intraocular pressure was raised in 4 patients, and it was controlled by topical antiglaucomatous treatment. CONCLUSION: Pars plana vitrectomy and intravitreal triamcinolone in eyes with chronic pseudophakic cystoid macular edema resulted in a reduction of cystoid macular edema, and visual acuity improvement.

[Intravitreal application of triamcinolone--our experiences]. / Nasa iskustva u intravitrealnoj primjeni triamcinolona.

AIM: To show the results of intravitreal application of triamcinolone used as a primary or adjuvant therapy. PATIENTS AND METHODS: We analyzed 48 patients with different ocular disorders: exudative age related macular degeneration, diabetic retinopathy, or central retinal vein occlusion. We analyzed color fundus photography, visual acuity, fluorescein angiography and complications of intravitreal triamcinolone application. RESULTS: There was a marked reduction of macular edema in 70% of patients verified on fluorescein angiography. Visual acuity improved in 62% of patients. The most common complication was transient rise in intraocular pressure. There was no case of endophthalmitis. CONCLUSION: Intravitreal application of triamcinolone is relatively safe and efficacious in selected patiens with different ocular disorders.

Postoperative outcomes after implantation of intraocular lenses in eyes with cataract and uveitis.

Despite advances in surgical technique and implant materials, cataract surgery in patients with uveitis is still a challenging procedure. We retrospectively evaluated postoperative outcomes of cataract surgery in 35 eyes of 29 patients with uveitis. Phacoemulsification with posterior chamber intraocular lens implantation was performed in all eyes. Postoperative evaluations were performed at day 2, and then at 7 days, 1, 3, and 6 months respectively. There were 16 males, and 13 females, aged 31 to 68 years. Follow-up ranged from 4 to 35 months. At final follow-up 33 eyes (94%) had an improvement in visual acuity compared with preoperative levels (p < 0,05). Giant cells were observed in the intraocular lens optic in 7 eyes (20%). Posterior capsule opacification occurred in 10 eyes (29%). Clinical cystoid macular edema was observed in 4 eyes, and 2 eyes required trabeculectomy with mitomycin C due to secondary glaucoma. Cataract surgery in patients with uveitis leads to successful visual results after correct surgical timing, and adequate anti-inflammatory therapy. There were no significant differences in the degree of inflammation after implantation of various types of intraocular lenses.

Phacoemulsification, vitrectomy and the implantation of an intraocular lens in diabetic patients.

The purpose of this study was to evaluate results of combined phacoemulsification, intraocular lens implantation and pars plana vitrectomy in patients with advanced diabetic retinopathy. We retrospectively evaluated postoperative outcomes and complications in 102 eyes of 102 patients who underwent a combined procedure. All patients had a visually significant cataract. Forty two patients had vitreous hemorrhage and mild proliferative diabetic retinopathy. Sixty patients had a mild tractional retinal detachment. The median follow up was 14 months (range 6-36 months). 80% of patients had an increase of visual acuity of at least 2 Snellen lines. The most frequent early postoperative complication was elevated intraocular pressure, followed by mild fibrinous reaction. The most frequent late postoperative complication was the presence of posterior synechia, followed by glaucoma. Eleven patients required a repeated pars plana vitrectomy. Combined phacoemulsification, posterior chamber intraocular lens implantation and pars plana vitrectomy can be successfully performed in selected diabetic patients with favorable postoperative outcome.