Dysfunction of VIPR2 leads to myopia in humans and mice.

BACKGROUND: Myopia is the leading cause of refractive errors. As its pathogenesis is poorly understood, we determined if the retinal VIP-VIPR2 signalling pathway axis has a role in controlling signalling output that affects myopia development in mice. METHODS: Association analysis meta-study, single-cell transcriptome, bulk RNA sequencing, pharmacological manipulation and VIPR2 gene knockout studies were used to clarify if changes in the VIP-VIPR2 signalling pathway affect refractive development in mice. RESULTS: The SNP rs6979985 of the VIPR2 gene was associated with high myopia in a Chinese Han cohort (randomceffect model: p=0.013). After either 1 or 2 days' form deprivation (FD) retinal VIP mRNA expression was downregulated. Retinal single-cell transcriptome sequencing showed that VIPR2 was expressed mainly by bipolar cells. Furthermore, the cAMP signalling pathway axis was inhibited in some VIPR2+ clusters after 2 days of FD. The selective VIPR2 antagonist PG99-465 induced relative myopia, whereas the selective VIPR2 agonist Ro25-1553 inhibited this response. In Vipr2 knockout (Vipr2-KO) mice, refraction was significantly shifted towards myopia (p<0.05). The amplitudes of the bipolar cell derived b-waves in 7-week-old Vipr2-KO mice were significantly larger than those in their WT littermates (p<0.05). CONCLUSIONS: Loss of VIPR2 function likely compromises bipolar cell function based on presumed changes in signal transduction due to altered signature electrical wave activity output in these mice. As these effects correspond with increases in form deprivation myopia (FDM), the VIP-VIPR2 signalling pathway axis is a viable novel target to control the development of this condition.

Posterior scleral reinforcement for the treatment of myopic traction maculopathy.

BACKGROUND: This study aimed to investigate the clinical effectiveness of posterior scleral reinforcement(PSR) for the treatment of myopic traction maculopathy (MTM). METHODS: This was a prospective study of 32 eyes from 20 patients with MTM treated with PSR using genipin-cross-linked donor sclera. The length of the scleral strip used for the surgery was designed to be 1.5-times the axial length of the eye, whereas its width was 0.4-times the axial length of the eye. The optical coherence tomography images, spherical equivalent of refractive error, axial length, best corrected visual acuity, electroretinogram findings, and intraocular pressure of the patients were assessed postoperatively. RESULTS: The mean duration of follow-up was 17.80 ± 8.74 months. The differences between the spherical equivalent of refractive error, best corrected visual acuity, axial length, and electroretinogram findings recorded preoperatively and those measured postoperatively were statistically significant (p < 0.05). The final reduction in axial length was 1.64 ± 0.85 mm. At the end of the follow-up, optical coherence tomography showed essential foveal reattachment in 30 eyes (93.75%), partial reattachment in two eyes (6.25%), and closure of macular holes in seven eyes (77.78%). No retinal detachment, vitreous haemorrhage, or other serious complications occurred following the surgery. CONCLUSIONS: Posterior scleral reinforcement with genipin-cross-linked sclera showed safe and effective outcomes for the treatment of MTM during a follow-up period of at least one year. TRIAL REGISTRATION: 11\12\2018, ChiCTR1800020012 .

EVALUATION OF THE EFFICACY OF POSTERIOR SCLERAL CONTRACTION IN THE TREATMENT OF MACULAR HOLE WITH RETINAL DETACHMENT IN HIGH MYOPIA.

PURPOSE: To evaluate efficacy of posterior scleral contraction for macular hole with retinal detachment in high myopia. METHODS: Seventy-three macular hole with retinal detachment eyes were treated with posterior scleral contraction. A strip was sent across inferior-temporal scleral surface to posterior pole, then two ends were led out from nasal-inferior to temporal-superior areas. It was tightened to contract posterior sclera with designed axial length shortening ([10% of preoperative axial length-0.5] mm) after aqueous humor was drained from anterior chamber. Recovery was classified as type I (retinal reattachment with MH bridged) and II (retinal reattachment without MH bridged). Follow-up duration was 25.3 ± 18.0 months. RESULTS: Axial length was 30.01 ± 2.27 mm at preoperation and shortened by 2.57 ± 0.82 mm intraoperatively. At final postoperation, maintained axial length shortening was 1.87 ± 0.92 mm. Forty-six eyes (63.0%) recovered as type I, 26 eyes (35.6%) as type II, and 1 eye (1.4%) unrecovered. Postoperative best-corrected visual acuity (logarithm of minimal angle of resolution) was better than preoperative one (0.85 ± 0.50 [Snellen 20/125] vs. 1.11 ± 0.56 [Snellen 20/250], P < 0.001) with correlation (r = 0.662, P < 0.001) and consistency (Kappa = 0.34, P < 0.001) between two. Best-corrected visual acuity improvement did not differ between recovery types (P = 0.206). CONCLUSION: Macular hole with retinal detachment was successfully recovered by posterior scleral contraction with axial length shortening. Visual improvement was achieved, correlated, and consistent with preoperative best-corrected visual acuity while independent of recovery types.

POSTERIOR SCLERAL CONTRACTION TO TREAT MYOPIC FOVEOSCHISIS IN HIGHLY MYOPIC EYES.

PURPOSE: To evaluate the efficacy of posterior scleral contraction to treat myopic foveoschisis (MF). METHODS: The records of MF patients treated with posterior scleral contraction were reviewed. During posterior scleral contraction, a cross-linked fusiform strip from allogeneic sclera was used and designed axial length (AL) shortening amount was around 2.0∼3.0 mm based on preoperative AL. The middle part of the strip was placed at the posterior pole of the eye. After few aqueous humors were released, the strip was tightened to contract posterior sclera and shorten AL. Clinical data were collected at pre-operation (op) and post-op follow-ups for 12 months. RESULTS: Twenty-four eyes were collected. The AL at pre-op, post-op 1-week, 3-month, 6-month, and 12-month were 29.84 ± 1.24, 27.39 ± 1.32, 27.73 ± 1.23, 27.86 ± 1.26, and 27.91 ± 1.29 mm. There was no AL difference between post-op 6-month and 12-month (P = 0.242). The accumulated MF reattachment rate at post-op 1-week, 3-month, 6-month, and 12-month were 8.3%, 16.7%, 50.5%, and 95.8%. The best-corrected visual acuity at post-op 6-month and 12-month were 0.71 ± 0.39 (Snellen acuity 20/80) and 0.64 ± 0.37 (Snellen acuity 20/63), improving significantly compared with pre-op (P = 0.006 and <0.001). CONCLUSION: The posterior scleral contraction was effective to treat MF. The AL stabilized after post-op 6-month and MF reattached gradually with improved visual acuity up to post-op 12-month.

POSTERIOR SCLERAL CONTRACTION TO TREAT RECURRENT OR PERSISTENT MACULAR DETACHMENT AFTER PREVIOUS VITRECTOMY IN HIGHLY MYOPIC EYES.

PURPOSE: To determine the efficacy of posterior scleral contraction (PSC) to treat recurrent or persistent macular detachment after previous vitrectomy in highly myopic eyes. METHODS: We reviewed the medical records of patients with high myopia and recurrent or persistent macular detachment after previous vitrectomy treated with PSC at our hospital between April 2013 and March 2017. Fourteen eyes (14 patients; mean age, 58.93 ± 11.08 years) were included. Sclera cross-linked with genipin was used for PSC. The desired axial length decrease was 0.1-fold. The reattachment rate, best-corrected visual acuity, and axial length changes were evaluated. RESULTS: The macular reattachment rate was 100%. In seven eyes with a silicone oil tamponade, the oil was successfully removed 2 weeks to 4 months after surgery. The best-corrected visual acuity improved significantly postoperatively (Snellen acuity improved from 20/1,000-20/400) (1.75 ± 0.90 vs. 1.34 ± 0.58 logarithm of the minimal angle of resolution; P < 0.05). Eight eyes (57.14%) improved; six eyes (43.86%) remained stable. The axial length decreased significantly postoperatively (31.32 ± 3.04 vs. 29.08 ± 3.05 mm; P < 0.05). CONCLUSION: Posterior scleral contraction is safe and effective for recurrent and persistent macular detachment after previous vitrectomy in highly myopic eyes. The silicone oil is removed after PSC, and vision can be preserved in these refractory cases.

[Effects of posterior chamber phakic intraocular lens on axial length measurements].

OBJECTIVE: To study the effects of posterior chamber phakic intraocular lens (IOL) on axial length (AL) measurements and whether a correction factor for later IOL power calculation before cataract surgery is necessary. METHODS: Twenty-two high myopic patients (39 eyes) with mean spherical equivalent -19.00 +/- 4.03 D received phakic refractive lens (PRL) implantation, and 24 patients (40 eyes) with mean spherical equivalent (-13.10 +/- 2.53) D received implantable Collamer lens (ICL) implantation. Pre-and postoperative AL measurements with the IOLMaster were compared. Results The pre-and postoperative ALs were (30.87 +/- 2.18) mm and (30.94 +/- 2.16) mm, respectively (t = -2.635, P = 0.012) in the PRL group, and (28.35 +/- 1.20) mm and (28.45 +/- 1.22) mm, respectively ( t = -3.97, P < 0.001) in the ICL group. Linear regression analysis showed: in the PRL group, preoperative AL = 1.01 x postoperative AL-0.24 (R2 = 0.99, P < 0.001), or postoperative AL--preoperative AL = 0.24-0.0055 x postoperative AL; in the ICL group, preoperative AL = 0.96 x postoperative AL +1.17 (R2 = 0.99, P < 0.001), or postoperative AL--preoperative AL = 0.0154 x postoperative AL -0.3763. The mean differences between pre-and postoperative ALs in the PRL and, ICL groups were 0.075 mm and 0.054 mm, respectively. CONCLUSIONS: Based on the SRK formula, a < 0.1 mm AL difference would result in a <0.25 D change in the calculated IOL power, possibly a < 0.20 D change in manifest refraction. Furthermore, for PRL, the longer the AL, the smaller the difference between pre-and postoperative ALs. These differences are so small that it is unnecessary to correct IOL power calculation.

Genetic variants at 13q12.12 are associated with high myopia in the Han Chinese population.

High myopia, which is extremely prevalent in the Chinese population, is one of the leading causes of blindness in the world. Genetic factors play a critical role in the development of the condition. To identify the genetic variants associated with high myopia in the Han Chinese, we conducted a genome-wide association study (GWAS) of 493,947 SNPs in 1088 individuals (419 cases and 669 controls) from a Han Chinese cohort and followed up on signals that were associated with p < 1.0 × 10(-4) in three independent cohorts (combined, 2803 cases and 5642 controls). We identified a significant association between high myopia and a variant at 13q12.12 (rs9318086, combined p = 1.91 × 10(-16), heterozygous odds ratio = 1.32, and homozygous odds ratio = 1.64). Furthermore, five additional SNPs (rs9510902, rs3794338, rs1886970, rs7325450, and rs7331047) in the same linkage disequilibrium (LD) block with rs9318086 also proved to be significantly associated with high myopia in the Han Chinese population; p values ranged from 5.46 × 10(-11) to 6.16 × 10(-16). This associated locus contains three genes-MIPEP, C1QTNF9B-AS1, and C1QTNF9B. MIPEP and C1QTNF9B were found to be expressed in the retina and retinal pigment epithelium (RPE) and are more likely than C1QTNF9B-AS1 to be associated with high myopia given the evidence of retinal signaling that controls eye growth. Our results suggest that the variants at 13q12.12 are associated with high myopia.

Posterior scleral reinforcement on progressive high myopic young patients.

PURPOSE: To evaluate the effect of posterior scleral reinforcement in controlling high myopic axial progression in young patients. METHODS: Only one eye of each patient had posterior scleral reinforcement surgery. Before surgery and at each postoperative follow-up, the best corrected visual acuity, intraocular pressure, refractive errors, indirect ophthalmoscopy, B-type ultrasonography, and IOLMASTER reflected light biometry were performed on both eyes. The changes of axial length and the changes of refractive errors from the baseline were compared between the surgery eyes and the contralateral eyes. RESULTS: Thirty patients had a mean age of 7.5 years and a mean spherical equivalent of -9.72 diopters. The mean elongation of axial length was significantly less in the surgery eye group than that in the contralateral eye group (0.75 mm vs. 0.94 mm, p < 0.0001, paired t test) after a mean follow-up of 895 days. The surgical effect was mild but maintained during the follow-up. The eyes with staphyloma gained less surgical effect when compared with the eyes without staphyloma (p = 0.0036). There was also a notable nonstatistically significant trend for younger patients to gain a larger surgical effect (p = 0.0986). CONCLUSIONS: Posterior scleral reinforcement surgery was found effective in slowing down high myopic axial progression in young patients within the study period, but the size of the effect was small. The surgical procedure is well tolerated without vision-threatening complications.

Exome sequencing reveals CCDC111 mutation associated with high myopia.

Myopia is a refractive error of the eye that is prevalent worldwide. The most extreme form, high myopia, is usually associated with other ocular disorders such as retinal detachment, macular degeneration, cataract, and glaucoma, and is one of leading causes of blindness. The etiology is complex and has not been fully elucidated. In this study, we identified a novel missense variant of the CCDC111 gene (NM_152683.2: c.265T > G; p.Y89D) in a high myopia family by exome sequencing. The variant was identified in 4 patients from an additional 270 sporadic high myopia patients, but not found in 270 controls. The amino acid is highly conserved across species, and variants giving rise to amino acid substitutions are predicted to be functionally damaging. The CCDC111 gene was ubiquitously expressed in primary cell cultures from human eye tissue, including corneal epithelial cells, choroidal melanoma cells, scleral fibroblasts, retinal epithelial cells, retinal Müller cells, and lens capsule epithelial cells. In summary, our results suggested that the CCDC111 may be a susceptibility gene for high myopia.

Interocular evaluation of axial length and retinal thickness in people with myopic anisometropia.

PURPOSE: To investigate the changes in axial length and retinal thickness and their relationships with myopia in highly myopic anisometropia. METHODS: A total of 87 Chinese subjects (25.28±11.98 years, mean±SD) were divided into two groups: anisometropia (n=38) and nonanisometropia (n=49). All eyes were measured for axial length, refractive status, and macular thickness (optical coherence tomography). Ocular biometric results were compared between eyes of subgroups. Linear correlation between refractive error and other biometric results was performed. RESULTS: In the anisometropic group, the inner ring macula and part of the outer ring macula (nasal and inferior quadrants) in the higher myopic eyes were significantly thinner than in the fellow eyes (P≤0.007), but the foveal thickness (minimum and average) was similar (P≥0.050) between the two eyes. However, the minimum and average foveal thicknesses were found to be significantly thicker in the highly myopic eyes than those in the emmetropic to moderate myopic eyes (P≤0.016) in the nonanisometropic group. Among the eyes ranging from emmetropia to high myopia, the refractive error was negatively correlated to the axial length of the eye (P<0.001) and the thinning of inner ring macula is consistent with the increase in both myopia and axial length. There was a negative correlation in refractive error and axial length but no correlation in parafoveal thickness between eyes of the same subjects (P<0.001) in the anisometropic group. CONCLUSIONS: In people with myopic anisometropia, the higher myopic eye has a longer axial length but a thinner parafoveal region than its fellow eye. The axial growth in the development of high myopia seems to be centrally regulated; however, the changes in parafoveal thickness are likely manipulated by local mechanisms within the eye.

Posterior scleral contraction to treat myopic traction maculopathy at different stages.

OBJECTIVE: We aimed to evaluate anatomical and functional outcomes and determine posterior scleral contraction (PSC) timing in treating myopic traction maculopathy (MTM). METHODS: This is a retrospective study of MTM patients undergoing PSC with genipin cross-linked strip at a single hospital site. Differences in demographic and clinical characteristics were compared among three groups defined by the MTM staging system. All patients were followed up for at least one year postoperatively. The best-corrected visual acuity (BCVA), macular hole diameter, axial length (AL), optical coherence tomography findings, and the complications were evaluated. Additionally, regression analyses were performed to account for confounders. RESULTS: Sixty-one MTM patients (24 eyes at stage 2, 22 eyes at stage 3, and 18 eyes at stage 4) were included. The macular holes were closed in 16 eyes (66.7%), 13 eyes (59.0%), and 11 eyes (61.1%) at stage 2, stage 3, and stage 4, respectively. PSC improved the BCVA in patients at each stage (all P < 0.05). Postoperative BCVA at stage 2 was significantly better than that at stage 4 (P = 0.0069). Preoperative BCVA was associated with postoperative BCVA (P < 0.001). Preoperative AL (OR 0.676, 95% CI 0.480 to 0.951, P = 0.025), AL shortening amount (OR 5.129, 95% CI 1.974 to 13.327, P = 0.001) and macular hole diameter (OR 1.003, 95% CI 1.000 to 1.006, P = 0.030) were associated with macular hole closure. CONCLUSIONS: PSC is safe and effective in treating MTM at different stages. Early PSC intervention will have more significant visual benefits.

Biomechanical Considerations of Patching Material for Posterior Scleral Reinforcement Surgery.

Purpose: To characterize biomechanical properties of genipin-crosslinked human dura mater as reinforcing material for posterior scleral reinforcement (PSR) and to compare it with crosslinked human sclera. Methods: Donor dura mater and sclera were crosslinked in the same optimized genipin solution. Resistance to enzyme degradation for both materials were investigated by exposing the materials to accelerated enzyme degrading. Elastic modulus and tensile strength were measured by biomechanics testing equipment. Crosslinked human dura mater was used as reinforcing patch in PSR on 57 adult pathologic myopic eyes. The patients were followed up for an average 3 years. The main outcome was eye globe axial length change and safety profile of the reinforcing material. Results: Crosslinked dura mater demonstrated similar percentage weight loss to crosslinked sclera when exposed to enzymatic solution. Dura mater has higher density than sclera. The retaining elastic modulus after enzyme exposure was 72.02 MPa for crosslinked dura mater while 53.88 MPa for crosslinked sclera, 34% greater for crosslinked dura mater, P = 0.0186). At the end of 3 years follow-up, the mean globe axis of the surgery eyes was reduced by 1.29 mm (from 30.81 to 29.51 mm, P < 0.0001, paired t-test). Visual acuity (BCVA logMar) improved by 0.10 logMar unit which is an improvement of five letters (P = 0.0184, paired t-test). No material specific complication was noted. Conclusion: Crosslinked human dura mater may be superior to crosslinked human sclera as reinforcing material for PSR to manage progression of high myopia. This material was well tolerated on human eye.

Vascular Changes of the Choroid and Their Correlations With Visual Acuity in Pathological Myopia.

Purpose: Photoreceptor loss plays a role in visual impairment in pathological myopia. As the nutrition and oxygen demands of photoreceptors are mainly supported by the choroidal vessels, we aimed to investigate changes in the choroidal vasculature and their correlations with visual acuity in pathological myopia. Methods: The cohort was composed of 136 eyes from 80 participants, including 42 eyes from 21 participants with emmetropia/low myopia, 48 eyes from 26 participants with simple high myopia, and 46 eyes from 33 participants with pathological myopia. Swept-source optical coherence tomography (OCT) was used to image the eyes with a 12-mm radial line scan protocol. The parameters for 6-mm diameters of macula area centered on the fovea were analyzed. A custom deep learning algorithm based on a modified residual U-Net architecture was used to segment the choroidal boundaries. Then, the distance between the two boundaries was determined and choroidal thickness (CT), luminal area (LA), and stromal area (SA) were demarcated based on Niblack's auto-local threshold algorithm after binarization of the OCT images. Finally, the ratio of LA and total choroidal area was defined as the choroidal vascularity index (CVI). The choroidal parameters in three groups were compared, and correlations of the choroidal parameters with age, gender, axial length, and best-corrected visual acuity (BCVA) were analyzed. Results: The CVI, CT, LA, and SA values were lower in pathological myopia than in emmetropia/low myopia and simple high myopia (P < 0.05). The CT, LA, and SA values were lower in simple high myopia than in emmetropia/low myopia (P < 0.05), whereas there was no difference between the CVIs in the emmetropia/low myopia and high myopia groups (P > 0.05). The CVI was nonlinear with increases in axial length (AL), and there was a critical AL flexion point, approximately 27.26 mm; however, the CT, LA, and SA were negatively correlated with AL. Further analysis showed that only younger subjects (40 years old or less) showed significant AL flexion points. Simple and multiple regression models showed that the CVI was correlated with BCVA (P < 0.05). Conclusions: Choroidal vascular alterations, especially decreased CVI, occurred in patients with pathological myopia. The CVI decreased with axial elongation beyond the flexion point and was correlated with visual impairment, indicating that the CVI might be a reliable imaging biomarker to monitor the progression of pathological myopia.

Assessment of exonic single nucleotide polymorphisms in the adenosine A2A receptor gene to high myopia susceptibility in Chinese subjects.

PURPOSE: The adenosine A(2A) receptor (A(2A)R) modulates collagen synthesis and extracellular matrix production in ocular tissues that contribute to eye growth and the development of myopia. We aimed to determine if single nucleotide polymorphisms (SNPs) in A(2A)R exons associates with high myopia found in Chinese subjects. METHODS: DNA samples were prepared from venous lymphocytes of 175 Chinese subjects with high myopia of less than -8.00 diopters (D) correction and 101 ethnically similar controls with between -1.00 D and +1.00 D correction. The coding region sequences of A(2A)R were amplified by PCR and analyzed by Sanger sequencing. The detected variations were confirmed by reverse sequencing. Allelic frequencies of all detected common SNPs were assessed for Hardy-Weinberg equilibrium. RESULTS: Five variations in A(2A)R exons, 5675 A>G, 5765 C>T, 13325 G>A, 13448 C>T, and 14000 T>A, were detected in controls at a low frequency (<1%). However, one SNP, 13772 T>C (rs5751876), showed its polymorphism in 53.3% of the total study population. The rs5751876 is a synonymous substitution located in a tyrosine codon of exon 2. Despite no significant difference in genotype distribution between cases and controls, the frequency of heterozygotes with the rs5751876 genotype was significantly lower in subjects with high myopia. CONCLUSIONS: The reduced frequency of the heterozygote rs5751876 genotype in subjects suggests a possible association of A(2A)R with high myopia in a Chinese population.

[Vitrectomy without internal limiting membrane peeling associated with gas tamponade for treatment of foveoschisis in pathologic myopia].

OBJECTIVE: To evaluate the efficacy of vitrectomy without internal limiting membrane (ILM) peeling associated with gas tamponade in eyes with myopic foveoschisis. METHODS: A prospective study was conducted, in which 49 pathological myopia patients (52 eyes) with myopic foveoschisis were enrolled and divided into three groups according to the different therapeutic procedures: 22 patients (24 eyes) underwent vitrectomy without internal limiting membrane (non-gas tamponade group), 15 patients (16 eyes) received vitrectomy without internal limiting membrane peeling but combined with gas tamponade (gas tamponade group) and 12 patients (12 eyes) did not receive surgical treatments (control group). SAS 9.13 was used for the statistic analysis. Best-corrected visual acuity (BCVA) and optical coherence tomographic (OCT) findings of the foveal thickness before and after the operation (the 3rd, 6th, and 9th month postoperatively) were obtained and compared by the Wilcoxon Rank-Sum test. Non-parameters Wilcoxon symbols test was used to compare the BCVA, the central foveal thickness (CFT) and maximum foveal thickness (MxFT) of each group before and after the surgery. RESULTS: Postoperative visual acuity was significantly increased in the two operation groups (t = 2.57, P < 0.05; t = 3.58, P < 0.05) but not increased in the control group (t = 1.84; P > 0.05). The difference of BCVA between these three groups was not significant (χ(2) = 0.24, P > 0.05). OCT showed the mean foveal thickness was significantly decreased postoperatively. Vitrectomy without peeling of the ILM significantly promoted the retinal reattachment in eyes with myopic foveoschisis. No retinal reattachment was found in the control group while 16 and 13 retinal reattachment were found in the non-gas tamponade (66.7%) and gas tamponade group (81.3%), the difference between these two operation groups and the control was statistically significant (χ(2) = 20.50, P < 0.05). During the follow-up, two eyes in the control group developed a macular hole and both developed retinal detachment (RD) in the 6 and 8 month, respectively. The remaining 10 eyes did not develop any complications, although the thickness of the macula increased significantly. A transient increase of intraocular pressure occurred in three eyes and had been cured by medications within 2 weeks after gas tamponade. A macular hole was recognized in one eye 2 months after surgery and the retina was reattached at the fovea 1 month after reoperation. CONCLUSIONS: Vitrectomy without ILM peeling could be a safe and effective surgical approach for the treatment of foveoschisis in pathologic myopia. In addition, gas tamponade can improve the success rate of the operation.

PDE4B Proposed as a High Myopia Susceptibility Gene in Chinese Population.

Myopia is the most common cause of refractive error worldwide. High myopia is a severe type of myopia, which usually accompanies pathological changes in the fundus. To identify high myopia susceptibility genes, DNA-pooling based genome-wide association analysis was used to search for a correlation between single nucleotide polymorphisms and high myopia in a Han Chinese cohort (cases vs. controls in discovery stage: 507 vs. 294; replication stage 1: 991 vs. 1,025; replication stage 2: 1,021 vs. 52,708). Three variants (rs10889602T/G, rs2193015T/C, rs9676191A/C) were identified as being significantly associated with high myopia in the discovery, and replication stage. rs10889602T/G is located at the third intron of phosphodiesterase 4B (PDE4B), whose functional assays were performed by comparing the effects of rs10889602T/T deletion of this risk allele on PDE4B and COL1A1 gene and protein expression levels in the rs10889602T/Tdel/del, rs10889602T/Tdel/wt, and normal control A549 cell lines. The declines in the PDE4B and COL1A1 gene expression levels were larger in the rs10889602T/T deleted A549 cells than in the normal control A549 cells (one-way ANOVA, p < 0.001). The knockdown of PDE4B by siRNA in human scleral fibroblasts led to downregulation of COL1A1. This correspondence between the declines in rs10889602 of the PDE4B gene, PDE4B knockdown, and COL1A1 protein expression levels suggest that PDE4B may be a novel high myopia susceptibility gene, which regulates myopia progression through controlling scleral collagen I expression levels. More studies are needed to determine if there is a correlation between PDE4B and high myopia in other larger sample sized cohorts.

Association analysis of retinoic acid receptor beta (RARbeta) gene with high myopia in Chinese subjects.

PURPOSE: High myopia or pathological myopia is a common refractive error. Individuals with high myopia are subject to increased risk of serious eye complications. Accumulating evidence has demonstrated the role for heritability in ocular growth and in the development of high myopia. Retinoic acid and retinoic acid receptors play important roles in ocular development and in experimentally induced myopia. The purpose of this study was to determine if high myopia is associated with single nucleotide polymorphism (SNP) variants in the retinoic acid receptor beta (RARbeta) gene in Chinese subjects. METHODS: DNA samples were purified from venous lymphocytes of 175 unrelated Chinese patients with high myopia (less than -8.00 diopters) and 101 Chinese control subjects without high myopia (+/-1.00 diopters). Direct nucleotide sequence analysis in the RARbeta gene was performed, and the detected variations were further confirmed by reverse sequencing. Allelic frequencies of all detected SNPs were assessed for Hardy-Weinberg equilibrium. RESULTS: Five variations in RARbeta were detected in Chinese subjects with high myopia, including 32574G>A, 32629G>A, 32645C>T, 32647T>G, and 151973C>T, of which only 32647T>G (NCBI notes as rs58244688 and rs2067964) had already been reported. The majority of SNP genotypes were heterozygous. While 32647T>G, 32629G>A, and 32645C>T were located in introns and 32574G>A and 151973C>T were located in coding regions, none of the SNPs affected the amino acid sequence. In the present study, no evidence of association was found between variations in the nucleotide sequence of RARbeta and high myopia. CONCLUSIONS: Five SNP variants in RARbeta were detected in Chinese subjects with high myopia, none of them were associated significantly with high myopia. Further studies are needed to identify which genes are responsible for high myopia.

Evaluation of BLID and LOC399959 as candidate genes for high myopia in the Chinese Han population.

PURPOSE: BH3-like motif containing, cell death inducer (BLID) and LOC399959 are two genes associated with the single nucleotide polymorphism (SNP) rs577948, which is a susceptibility locus for high myopia in Japanese subjects. The purpose of this study was to determine if BLID and LOC399959 are associated with high myopia in Chinese Han subjects. METHODS: High myopia subjects (n=476) had a spherical refractive error of less than -6.00 D in at least one eye and/or an axial length greater than 26 mm. Genomic DNA was extracted and genotyped from peripheral blood leukocytes of high myopes and controls (n=275). Using a case-control association study of candidate regions, linkage disequilibrium blocks for 19 tag SNPs (tSNPs), including rs577948, harbored within and surrounding the BLID and LOC399959 genes were analyzed on a MassArray platform using iPlex chemistry. Each of the tSNPs had an r(2)>0.8 and minor allele frequency >10% in the Chinese Han population. Haplotype association analysis was performed on Haploview 4.1 using Chi-square (χ(2)) tests. RESULTS: None of the 19 tSNPs were statistically associated with high myopia. CONCLUSIONS: While rs577948 may be associated with high myopia in Japanese subjects, it and the other tSNPs near the BLID and LOC399959 genes are not susceptibility loci for high myopia in the Chinese Han population. Thus, associations of SNPs with high myopia as determined by Genome-Wide Association Study (GWAS) may be restricted to certain ethnic or genetically distinct populations. Without systematic replication in other populations, the results of GWAS associations should be interpreted with great caution.

[Three-year follow-up of iris-claw phakic intraocular lens implantation for high myopia].

OBJECTIVE: To investigate long-term efficacy and safety of an iris-claw phakic intraocular lens (ICPIOL) implantation for high myopia. METHODS: A consecutive group of 86 eyes in 49 patients with -15.33±3.81 diopters (D) of myopia was implanted with the Artisan ICPIOL (Ophtec), and was evaluated preoperatively and 1, 2, 3 years postoperatively. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest refraction, intraocular pressure, and complications were evaluated. RESULTS: The implantation was successful in all of 86 eyes. Compared with preoperative data, UCVA, BCVA, and spherical equivalent (SE) were improved significantly (F=513.68, 20.88, 827.65; P<0.01). At 3-year postoperatively, UCVA in 85% eyes was 0.5 or better, in 35% was 0.8 or better; No loss of BCVA was found, 17% gained 1 line, and 59% gained 2 lines or more; SE in 81%, 54% eyes was within ±1.00 D, ±0.50 D of attempted, respectively. At 1-, 2-, 3-year follow-up, the corneal endothelial loss was 3.60%, 5.78%, 7.74%, respectively. There were 2 macular haemorrhages resulted from CNV, and 1 ICPIOL repositioning due to inappropriate iris capture. No other severe complications occurred. CONCLUSION: At 3-year follow-up, the implantation of the ICPIOL proved to be safe and effective for the correction of myopia in phakic eyes.

[Change of accommodative function in phakic eyes with iris-fixated phakic intraocular lens implantation].

OBJECTIVE: To evaluate the changes of accommodative function after implantation of iris-fixated phakic intraocular lens (IFPIOL) for correction of high myopia, and compared with gender and age matched emmetropes. This study also provides clinical basis for assessing the quality of life after implantation of the IFPIOL. METHODS: It was a case-control study. Iris-fixated in phakic intraocular lens implantation was performed in 23 eyes of 12 high myopic patients. Control group included 22 eyes in 11 emmetropes. All patients and controlled subjects had the same examinations including amplitude of accommodation, accommodative facility test, and negative/positive relative accommodation before, 1 month and 3 months after operation. Surgery was performed by the same surgeon. Randomized block design analysis of variance was applied to analyze accommodative function between the patients preoperative and postoperative, and two independent samples t-test was applied to analyze accommodative function between the control group and the patients. P value less than 0.05 was considered significant. RESULTS: The mean amplitude of accommodation at 1 month and 3 months was (8.90 ± 2.13) D and (9.10 ± 1.72) D after IFPIOL implantation, respectively. Mean amplitude of accommodation after the operation was significantly greater than that from preoperative eyes (7.35 ± 2.20) D, (F = 19.88, P < 0.01). Mean amplitude of accommodation at 3 months in eyes after IFPIOL implantation showed no significant difference (t = -1.76, P = 0.09) as compared with the control group (10.10 ± 2.09) D. Mean accommodative facility at 1 month and 3 months after IFPIOL implantation was (8.17 ± 2.09) cyc/min and (8.67 ± 1.80) cyc/min, respectively. This was significantly increased from preoperative data which was (5.67 ± 1.53) cyc/min, (F = 64.27, P < 0.01). Mean accommodative facility at 3 months after IFPIOL implantation had no statistically significant difference (t = -6.29, P < 0.01) as compared with the control group (14.51 ± 3.81) cyc/min. In addition, mean positive relative accommodation (2.45 ± 0.81) D was significantly greater than that in preoperative eyes (1.61 ± 0.80) D, (F = 6.10, P = 0.01) but, not significantly different (t = -2.83, P = 0.01) from the control group (3.89 ± 1.49) D. CONCLUSIONS: Patients can obtain physiological accommodative function after the implantation of IFPIOL for correction of high myopia. Moreover, the accommodative function increases with time and is stable. Nevertheless, accommodative function could not reach the level of normal emmetropic eyes. Longer-term results would be further observed.