Quantifying refractive error in companion dogs with and without nuclear sclerosis: 229 eyes from 118 dogs.

OBJECTIVE: To evaluate the relationship between nuclear sclerosis (NS) and refractive error in companion dogs. ANIMALS STUDIED: One hundred and eighteen companion dogs. PROCEDURES: Dogs were examined and found to be free of significant ocular abnormalities aside from NS. NS was graded from 0 (absent) to 3 (severe) using a scale developed by the investigators. Manual refraction was performed. The effect of NS grade on refractive error was measured using a linear mixed effects analysis adjusted for age. The proportion of eyes with >1.5 D myopia in each NS grade was evaluated using a chi-square test. Visual impairment score (VIS) was obtained for a subset of dogs and compared against age, refractive error, and NS grade. RESULTS: Age was strongly correlated with NS grade (p < .0001). Age-adjusted analysis of NS grade relative to refraction showed a mild but not statistically significant increase in myopia with increasing NS grade, with eyes with grade 3 NS averaging 0.58-0.88 D greater myopia than eyes without NS. However, the myopia of >1.5 D was documented in 4/58 (6.9%) eyes with grade 0 NS, 12/91 (13.2%) eyes with grade 1 NS, 13/57 (22.8%) eyes with grade 2 NS, and 7/23 (30.4%) eyes with grade 3 NS. Risk of myopia >1.5 D was significantly associated with increasing NS grade (p = .02). VIS was associated weakly with refractive error, moderately with age, and significantly with NS grade. CONCLUSIONS: NS is associated with visual deficits in some dogs but is only weakly associated with myopia. More work is needed to characterize vision in aging dogs.

Comparison in conjunctival-Tenon's capsule thickness, anterior scleral thickness and ciliary muscle dimensions between Caucasians and Hispanic by optical coherence tomography.

PURPOSE: To investigate the differences in the dimensions of the anterior ocular segment, and specifically in conjunctival-Tenon's capsule thickness (CTT), anterior scleral thickness (AST) and ciliary muscle thickness (CMT), between Caucasian and Hispanic subjects using swept-source optical coherence tomography (SS-OCT). METHODS: Cross-sectional study including 53 Hispanic and 60 Caucasian healthy participants, matched by age, sex and refractive error, who underwent a complete ophthalmological examination. CTT, AST and CMT were manually measured in the temporal and nasal quadrants at 0, 1, 2 and 3 mm from the scleral spur using SS-OCT. RESULTS: Mean age and refractive error were 38.7 ± 12.3 years and -1.05 ± 2.6 diopters, and 41.8 ± 11.7 years and -0.50 ± 2.6 diopters for the Hispanic and Caucasians, respectively (p = 0.165 and p = 0.244). The CTT was increased in the temporal quadrant in the Hispanic group in the three studied regions (CTT1, CTT2 and CTT3; being the means 223.0 ± 68.4, 215.3 ± 66.4 and 203.8 ± 67.1 µm versus 190.8 ± 51.0, 189.4 ± 53.2 and 187.4 ± 55.3 µm respectively; p < 0.001). Larger AST values were observed in the temporal quadrant in the Hispanic group (AST2: 559.8 ± 80.8 µm and AST3: 591.6 ± 83.0 µm) compared to the Caucasian group (520.7 ± 50.1 and 558.9 ± 54.7 respectively; p ≤ 0.022). No differences were observed in the nasal quadrant for CTT, AST1 and AST3 (p ≥ 0.076). No differences emerged in the CM dimensions (p ≥ 0.055). CONCLUSION: CTT and AST measurements were thicker in the temporal quadrant of Hispanic patients compared to Caucasians. This could have implications for the pathogenesis of different ocular diseases.

Effects of blue light-exposed retinal pigment epithelial cells on the process of ametropia.

Ametropia is one of the most common ocular disorders worldwide, to which almost half of visual impairments are attributed. Growing evidence has linked the development of ametropia with ambient light, including blue light, which is ubiquitous in our surroundings and has the highest photonic energy among the visible spectrum. However, the underlying mechanism of blue light-mediated ametropia remains controversial and unclear. In the present study, our data demonstrated that exposure of the retinal pigment epithelium (RPE) to blue light elevated the levels of the vital ametropia-related factor type Ⅰ collagen (COL1) via ß-catenin inhibition in scleral fibroblasts, leading to axial ametropia (hyperopic shift). Herein, our study provides evidence for the vital role of blue light-induced RPE dysfunction in the process of blue light-mediated ametropia, providing intriguing insights into ametropic aetiology and pathology by proposing a link among blue light, RPE dysfunction and ametropia.

Non-additive (dominance) effects of genetic variants associated with refractive error and myopia.

Genome-wide association studies (GWAS) have revealed that the genetic contribution to certain complex diseases is well-described by Fisher's infinitesimal model in which a vast number of polymorphisms each confer a small effect. Under Fisher's model, variants have additive effects both across loci and within loci. However, the latter assumption is at odds with the common observation of dominant or recessive rare alleles responsible for monogenic disorders. Here, we searched for evidence of non-additive (dominant or recessive) effects for GWAS variants known to confer susceptibility to the highly heritable quantitative trait, refractive error. Of 146 GWAS variants examined in a discovery sample of 228,423 individuals whose refractive error phenotype was inferred from their age-of-onset of spectacle wear, only 8 had even nominal evidence (p < 0.05) of non-additive effects. In a replication sample of 73,577 individuals who underwent direct assessment of refractive error, 1 of these 8 variants had robust independent evidence of non-additive effects (rs7829127 within ZMAT4, p = 4.76E-05) while a further 2 had suggestive evidence (rs35337422 in RD3L, p = 7.21E-03 and rs12193446 in LAMA2, p = 2.57E-02). Accounting for non-additive effects had minimal impact on the accuracy of a polygenic risk score for refractive error (R2 = 6.04% vs. 6.01%). Our findings demonstrate that very few GWAS variants for refractive error show evidence of a departure from an additive mode of action and that accounting for non-additive risk variants offers little scope to improve the accuracy of polygenic risk scores for myopia.

OBSERVATION OF VITREOUS FEATURES USING ENHANCED VITREOUS IMAGING OPTICAL COHERENCE TOMOGRAPHY IN HIGHLY MYOPIC RETINOSCHISIS.

PURPOSE: To observe features of the posterior vitreous and vitreoretinal interface in highly myopic eyes with retinoschisis using enhanced vitreous imaging optical coherence tomography. METHODS: Comprehensive ophthalmologic examination and enhanced vitreous imaging optical coherence tomography were performed in 77 eyes of 63 patients with highly myopic retinoschisis. Two different modes of spectral domain optical coherence tomography were employed to estimate retinoschisis and the posterior vitreous features in optical coherence tomography images, respectively. The types and distribution of vitreoretinal interface abnormalities were also analyzed. RESULTS: Complete posterior vitreous detachment (PVD) was identified in 55 eyes (71.4%) with a Weiss ring. Residual cortex was found in 39 eyes (70.9%) with complete PVD. Vitreoretinal interface changes, including vitreoretinal adhesion and epiretinal membrane (ERM), most frequently appeared in the macular area (47.3%), followed by the inferior arched vessels region (34.5%). In partial PVD eyes, vitreoretinal traction, vitreoretinal adhesion, and epiretinal membrane tended to be observed in the inferior and superior arched vessels regions (54.5 and 40.9%, respectively). Among all types of vitreoretinal interface abnormalities, epiretinal membrane comprised the largest proportion (46.8%) despite the status of PVD. The presence of inner layers of retinoschisis connoted a relatively high possibility of vitreoretinal interface abnormalities occurring. CONCLUSION: Enhanced vitreous imaging optical coherence tomography reveals a high prevalence of vitreoretinal interface abnormalities in highly myopic eyes with retinoschisis. Vitreous cortex tends to remain on the macular area in eyes with complete PVD. Our findings may lead to better guidance for the surgical treatment of highly myopic retinoschisis.

General formula to design a freeform singlet free of spherical aberration and astigmatism.

In this paper, an analytical closed-form formula for the design of freeform lenses free of spherical aberration and astigmatism is presented. Given the equation of the freeform input surface, the formula gives the equation of the second surface to correct the spherical aberration. The derivation is based on the formal application of the variational Fermat principle under the standard geometrical optics approximation.

Accuracy and Repeatability of an Anterior Segment Swept-Source Optical Coherence Tomographer.

OBJECTIVES: To assess accuracy and repeatability of the CASIA swept-source optical coherence tomographer (SS-OCT) in measuring contact lens (CL) radii of curvature and thicknesses compared with verified CL parameters and to investigate intrasession and intersession repeatability of the CASIA SS-OCT in measuring epithelial and total corneal thicknesses. METHODS: Rigid CLs with varying radii of curvature (front, rf; back, rb) and thicknesses were imaged with the CASIA SS-OCT across two sessions. Contact lens parameters were measured from processed images using an automated MATLAB program and were compared with parameters verified using standard techniques. Central epithelial and total corneal thicknesses of 43 normal subjects were measured to assess intrasession and intersession repeatability of the CASIA SS-OCT. RESULTS: No significant differences (P>0.05) were found in rigid CL rf and central and peripheral thickness measurements compared with verified CL parameters. However, the rb values obtained from the CASIA SS-OCT were consistently 0.2 mm flatter than the verified rb values (P<0.001) along horizontal and vertical meridians. Bland-Altman analysis revealed excellent intrasession agreement with mean differences of 0.004 and 0.003 mm for rf and rb, 0.000 mm for CL thickness and 0.372 and 0.395 µm for epithelial and total corneal thicknesses, respectively. Similarly, mean intersession differences of 0.020 and 0.000 mm for rf and CL thickness and 0.100 and 0.984 µm for epithelial and total corneal thicknesses were found, respectively. Ninety-five percentage confidence intervals across one or two sessions indicated insignificant undermeasurement or overmeasurement for CL rf, and corneal thicknesses, but significant bias toward overmeasurement for CL rb was found across two sessions. CONCLUSIONS: The CASIA SS-OCT produces accurate measurements of CL parameters compared with verified values. Inbuilt distortion correction in this instrument necessitated no further correction of scanned images and provided high intrasession and intersession repeatability in measuring both CLs and corneal thicknesses. Further investigation of discrepancies in rb measurements is warranted.

Effects of Preoperative Topometric Indices on Visual Gain After Intracorneal Ring Segment Implantation For Keratoconus.

OBJECTIVES: To assess the corneal topometric parameters that can be predictive for better visual gain after intracorneal ring segment (ICRS) implantation in eyes with keratoconus. METHODS: A total of 42 eyes of 32 patients who underwent ICRS implantation at Dokuz Eylul University, Deparment of Ophthalmology, Cornea Divison were included. Changes in uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive errors, and corneal topometric indices measured using Scheimpflug topography (Pentacam, Oculus) were evaluated retrospectively. RESULTS: After creation of intrastromal tunnels of 5.01±0.03 mm inner diameter, 5.71±0.03 mm outer diameter and at 384.21±34.12 µm depth, 1 or 2 ICRS of 150 to 350 µm thickness and 90 to 210° arc length were implanted. Preoperative UDVA of 0.09±0.10 and CDVA of 0.29±0.14 Snellen lines improved postoperatively to 0.42±0.26 and 0.62±0.24, respectively (P<0.001 for both). Preoperative spherical equivalent of -6.35±4.58D and refractive astigmatism of -5.89±2.40D decreased to -3.59±3.86 and -2.25±1.66D, retrospectively (P<0.001 for both). Strong negative correlations were detected between preoperative mean simulated keratometry (SimKavg)/index of surface variance (ISV) and changes in UDVA/CDVA (P<0.01, for all). Postoperative change in ISV was positively correlated with thicknesses of implanted rings. Change in topographical keratoconus classification was positively and change in index of vertical asymmetry was negatively correlated with number of implanted rings (P<0.05 for all). CONCLUSIONS: Preoperative ISV value seems to be beneficial in predicting visual gain after ICRS implantation, in addition to SimKavg. Future work on new nomograms for ICRS selection that include ISV, besides refractive, topographic, and cone location data, is warranted.

Bilateral optic disc pathologies as an accompanying feature of comitant strabismus in children.

PURPOSE: To describe and report accompanying bilateral optic disc pathologies in children with comitant strabismus. METHODS: Twenty-eight patients (16 female, 12 male) aged between 1 and 12 years who had comitant strabismus and bilateral optic disc pathologies were included in the study. Visual acuity, refractive errors, amount of deviation and types of optic disc pathologies were all recorded. Each patient underwent complete neurological and ophthalmological examination. RESULTS: Of the 28 patients, 14 (50.0%) had esotropia and 14 (50.0%) had exotropia. The mean age was 4.18 ± 3.03 years. The mean deviation angle was 35.30 ± 13.26 prism diopters (PD) (20-70 PD). Optic atrophy as being the most common pathology was found in nine (32.1%) patients. Six (21.4%) patients had temporal disc pallor, six (21.4%) patients had optic nerve hypoplasia, and seven (25%) patients had other optic disc anomalies (tilted disc, megalodisc, disc coloboma, peripapillary staphyloma). Optic disc pathologies were found to be isolated in 12 patients. Nine of 13 patients with congenital optic disc pathologies had esotropia, whereas 10 of 15 patients with optic atrophy or optic disc pallor had exotropia. CONCLUSION: Comitant strabismus in children can be associated with congenital or acquired optic disc pathologies. It is worthy of note that esotropia was more common in patients with congenital optic disc pathologies, whereas exotropia was more frequent in patients with optic atrophy or optic disc pallor. The findings of the present study show that complete ophthalmological examination including fundus evaluation should be carried out in all patients with strabismus even though the cause of ocular misalignment is obvious.

Choroidal thickness alterations in diabetic nephropathy patients with early or no diabetic retinopathy.

PURPOSE: To assess changes in choroidal thickness (CT) in diabetes patients with and without diabetic nephropathy using enhanced depth imaging spectral domain optical coherence tomography (EDI-OCT). METHODS: Thirty-five type 2 diabetes patients with a diagnosis of diabetic nephropathy (DNP) in nephrology department and 35 type 2 diabetes patients without nephropathy (non-DNP) were included in our prospective study consecutively. The control group comprised 34 healthy individuals. CT measurements were recorded under the fovea and at 1500 µm from the foveal center in the nasal and temporal sides. The study parameters also included age, refractive error, axial length, intraocular pressure, HbA1c, glomerular filtration rate and proteinuria amount. RESULTS: The subfoveal, temporal and nasal choroidal thickness was noted to be thinner in patients with DNP compared with non-DNP and normal subjects (p < 0.05). However, CT measurements did not show any difference between the healthy and non-DNP group. CONCLUSION: CT decreases significantly in diabetic patients when diabetic nephropathy accompanies diabetes mellitus.

CHOROIDAL THICKNESS IN HEALTHY CHINESE CHILDREN AGED 6 to 12: The Shanghai Children Eye Study.

PURPOSE: To explore the characteristics of choroidal thickness (ChT) in Chinese children. METHODS: A total of 144 healthy children, aged 6 years to 12 years old, were enrolled in the study. The ChT of subfovea and peripheral locations 0.5, 1.5, and 2.5 mm away from the fovea were evaluated by enhanced depth imaging optical coherence tomography. The association between subfoveal ChT and systemic, as well as ocular factors, including age, sex, height, weight, body mass index, axial length, refractive error, intraocular pressure, preterm history, and the refractive status of parents were studied. RESULTS: The mean subfoveal ChT was 302 ± 63 µm. In the nasal, superior, and inferior areas, the ChT of locations closer to the fovea was thicker than those farther away from the fovea (all P < 0.05); however, ChT was not significantly different among different locations in the temporal area (P = 0.16). The ChT of the nasal quadrant was significantly thinner than that of other areas (P < 0.01). Subfoveal ChT decreased with age, axial length, preterm history, and increased with height. Sex was not statistically associated with subfoveal ChT. CONCLUSION: In Chinese children, the ChT is thinnest in the nasal quadrant and thicker in central regions than in peripheral areas. The subfoveal ChT independently decreases with age, axial length, preterm history, and increases with height.

Characteristics of higher-order aberrations and anterior segment tomography in patients with pathologic myopia.

PURPOSE: To investigate prospectively the characteristics in the higher-order aberrations and anterior segment tomography in patients with pathologic myopia. METHODS: One hundred and twelve consecutive highly myopic patients (mean age 43.4 ± 9.3 years, spherical equivalent of refractive error ≥8 D and an axial length ≥26.5 mm) were studied. Thirty-seven emmetropic individuals (mean age 37.0 ± 14.5 years, spherical equivalent of refractive error ≤ ±1 D) were analyzed as controls. The ocular and cornea higher-order aberrations were measured using a Hartmann-Shack wavefront sensor (KR-1W; Topcon Corporation, Tokyo, Japan). The crystalline lens rise, the angle-to-angle, and the white-to-white values were measured using anterior segment OCT (SS-1000; Tomey Corporation, Nagoya, Japan). The mean curvature of the anterior corneal surface, the thickness at the thinnest central corneal point, the location of the central corneal point, the corneal volume, the anterior chamber volume, and the anterior chamber depth were measured using the Pentacam HR (Oculus, Inc., Wetzlar, Germany). RESULTS: The ocular total higher-order aberration for 4-mm pupil, the ocular spherical aberrations, and internal spherical aberration for 6-mm pupil were significantly higher in highly myopic eyes than in the emmetropic controls. The crystalline lens rise was significantly smaller in highly myopic eyes than in the emmetropic controls. The anterior chamber depth and the anterior chamber volume were significantly larger in highly myopic eyes than in the emmetropic controls. CONCLUSION: Highly myopic eyes had higher-order aberrations than emmetropic eyes because of the increasing internal aberrations.

Axial length/corneal radius of curvature ratio and refractive status in an adult Nigerian population.

AIM/BACKGROUND: Associations between axial length (AL) to corneal radius of curvature (CR) ratio and refractive status in a healthy Nigerian adult population were studied. MATERIALS AND METHODS: Healthy students and members of staff of Obafemi Awolowo Teaching Hospitals Complex, Ile-Ife, South West Nigeria, free of obvious ocular diseases except possible refractive errors were recruited. Consecutive consenting volunteers were recruited by simple random sampling and a proportionate sample of each population based on its representative fraction in the hospital community was recruited. The study was conducted between June and August 2011. Noncycloplegic objective refraction was done and spherical equivalent refraction (SER) of the right eyes was used for calculation. The AL, CR, and keratometric readings were measured with the IOL Master. The AL/CR ratio was calculated. The data were analyzed with statistical software package STATA 13. RESULTS: Three hundred and fifty volunteers aged 18-60 years were studied. The mean ± standard deviation of AL/CR and SER were 3.04 ± 0.10 and -0.38 ± 1.42D, respectively. AL in myopia was significantly higher than in emmetropia and hypermetropia. There were no significant differences between CR in the refraction groups. Myopes had significantly higher AL/CR than nonmyopes. On controlling for age and gender, 1 mm increase in AL increased SER by -0.77D (95% confidence interval [CI] -0.91--0.64D) while a unit increase in AL/CR increased SER by -8.89D (95% CI -10.00--7.78D). Whereas AL accounts for 39% of variability in SER (P < 0.001), AL/CR accounts for 51% of the variability observed in SER (P < 0.001). CONCLUSION: This study has further confirmed that the AL remains a strong determinant of refraction, but a derived factor AL/CR accounts for more variation in final refractive status than AL in isolation.

Education influences the association between genetic variants and refractive error: a meta-analysis of five Singapore studies.

Refractive error is a complex ocular trait governed by both genetic and environmental factors and possibly their interplay. Thus far, data on the interaction between genetic variants and environmental risk factors for refractive errors are largely lacking. By using findings from recent genome-wide association studies, we investigated whether the main environmental factor, education, modifies the effect of 40 single nucleotide polymorphisms on refractive error among 8461 adults from five studies including ethnic Chinese, Malay and Indian residents of Singapore. Three genetic loci SHISA6-DNAH9, GJD2 and ZMAT4-SFRP1 exhibited a strong association with myopic refractive error in individuals with higher secondary or university education (SHISA6-DNAH9: rs2969180 A allele, ß = -0.33 D, P = 3.6 × 10(-6); GJD2: rs524952 A allele, ß = -0.31 D, P = 1.68 × 10(-5); ZMAT4-SFRP1: rs2137277 A allele, ß = -0.47 D, P = 1.68 × 10(-4)), whereas the association at these loci was non-significant or of borderline significance in those with lower secondary education or below (P for interaction: 3.82 × 10(-3)-4.78 × 10(-4)). The evidence for interaction was strengthened when combining the genetic effects of these three loci (P for interaction = 4.40 × 10(-8)), and significant interactions with education were also observed for axial length and myopia. Our study shows that low level of education may attenuate the effect of risk alleles on myopia. These findings further underline the role of gene-environment interactions in the pathophysiology of myopia.

Nine loci for ocular axial length identified through genome-wide association studies, including shared loci with refractive error.

Refractive errors are common eye disorders of public health importance worldwide. Ocular axial length (AL) is the major determinant of refraction and thus of myopia and hyperopia. We conducted a meta-analysis of genome-wide association studies for AL, combining 12,531 Europeans and 8,216 Asians. We identified eight genome-wide significant loci for AL (RSPO1, C3orf26, LAMA2, GJD2, ZNRF3, CD55, MIP, and ALPPL2) and confirmed one previously reported AL locus (ZC3H11B). Of the nine loci, five (LAMA2, GJD2, CD55, ALPPL2, and ZC3H11B) were associated with refraction in 18 independent cohorts (n = 23,591). Differential gene expression was observed for these loci in minus-lens-induced myopia mouse experiments and human ocular tissues. Two of the AL genes, RSPO1 and ZNRF3, are involved in Wnt signaling, a pathway playing a major role in the regulation of eyeball size. This study provides evidence of shared genes between AL and refraction, but importantly also suggests that these traits may have unique pathways.

Five-Year Progression of Refractive Errors and Incidence of Myopia in School-Aged Children in Western China.

BACKGROUND: To determine the change in refractive error and the incidence of myopia among school-aged children in the Yongchuan District of Chongqing City, Western China. METHODS: A population-based cross-sectional survey was initially conducted in 2006 among 3070 children aged 6 to 15 years. A longitudinal follow-up study was then conducted 5 years later between November 2011 and March 2012. Refractive error was measured under cycloplegia with autorefraction. Age, sex, and baseline refractive error were evaluated as risk factors for progression of refractive error and incidence of myopia. RESULTS: Longitudinal data were available for 1858 children (60.5%). The cumulative mean change in refractive error was -2.21 (standard deviation [SD], 1.87) diopters (D) for the entire study population, with an annual progression of refraction in a myopic direction of -0.43 D. Myopic progression of refractive error was associated with younger age, female sex, and higher myopic or hyperopic refractive error at baseline. The cumulative incidence of myopia, defined as a spherical equivalent refractive error of -0.50 D or more, among initial emmetropes and hyperopes was 54.9% (95% confidence interval [CI], 45.2%-63.5%), with an annual incidence of 10.6% (95% CI, 8.7%-13.1%). Myopia was found more likely to happen in female and older children. CONCLUSIONS: In Western China, both myopic progression and incidence of myopia were higher than those of children from most other locations in China and from the European Caucasian population. Compared with a previous study in China, there was a relative increase in annual myopia progression and annual myopia incidence, a finding which is consistent with the increasing trend on prevalence of myopia in China.

Three-dimensional ray-tracing model for the study of advanced refractive errors in keratoconus.

We propose a numerical three-dimensional (3D) ray-tracing model for the analysis of advanced corneal refractive errors. The 3D modeling was based on measured corneal elevation data by means of Scheimpflug photography. A mathematical description of the measured corneal surfaces from a keratoconus (KC) patient was used for the 3D ray tracing, based on Snell's law of refraction. A model of a commercial intraocular lens (IOL) was included in the analysis. By modifying the posterior IOL surface, it was shown that the imaging quality could be significantly improved. The RMS values were reduced by approximately 50% close to the retina, both for on- and off-axis geometries. The 3D ray-tracing model can constitute a basis for simulation of customized IOLs that are able to correct the advanced, irregular refractive errors in KC.

Interocular symmetry of the peripapillary choroidal thickness and retinal nerve fibre layer thickness in healthy adults with isometropia.

BACKGROUND: The aim of this study was to determine the interocular differences in the peripapillary retinal nerve fibre layer (RNFL), peripapillary choroidal thickness (PCT) and subfoveal choroidal thickness (SFCT) in healthy adults with isometropia, using enhanced depth imaging optical coherence tomography (EDI SD-OCT). METHODS: One hundred healthy Chinese adults with spherical equivalents of ≤ ±3 dioptres and interocular differences of <0.5 dioptres were prospectively enrolled in this study. They underwent RNFL and PCT measurements via EDI SD-OCT, with a 3.4 mm scan circle centred on the optic nerve head. Subfoveal choroidal thickness (SFCT) measurements were also taken with a horizontal line scan centred on the macula. Right and left eyes were compared by a paired t-test, and the interocular differences were calculated. The agreement and correlations of the RNFLs, PCTs and SFCTs between the right and left eyes were analysed. RESULTS: Eighty-six subjects (172 eyes) were included in the final analysis, consisting of 44 (51.6 %) males and 42 (48.8 %) females; 55 (63.9 %) had emmetropia and 33 (36.1 %) had ametropia. The RNFL was statistically significantly thicker in the right eyes when compared to the left eyes in the temporal quadrant, and thinner on average in the nasal superior quadrant (p < 0.05). However, the differences in the choroidal thicknesses in all of the quadrants between the right and left eyes were not statistically significant. The tolerance limits of the average RNFL were -21.1 µm and 7.1 µm, and the mean and standard deviation of the interocular difference in the average PCT was -2.2 ± 24.2 µm. The RNFLs and PCTs in all of the locations in the right eyes were significantly correlated with those in the left eyes. However, no significant associations between the age, sex, interocular asymmetry of spherical the equivalent or interocular differences in the RNFL and PCT were detected. CONCLUSION: The PCT did not differ significantly between the right and left eyes, although interocular asymmetry of the RNFL existed in this Chinese population with isometropia.

Genome-wide analysis points to roles for extracellular matrix remodeling, the visual cycle, and neuronal development in myopia.

Myopia, or nearsightedness, is the most common eye disorder, resulting primarily from excess elongation of the eye. The etiology of myopia, although known to be complex, is poorly understood. Here we report the largest ever genome-wide association study (45,771 participants) on myopia in Europeans. We performed a survival analysis on age of myopia onset and identified 22 significant associations ([Formula: see text]), two of which are replications of earlier associations with refractive error. Ten of the 20 novel associations identified replicate in a separate cohort of 8,323 participants who reported if they had developed myopia before age 10. These 22 associations in total explain 2.9% of the variance in myopia age of onset and point toward a number of different mechanisms behind the development of myopia. One association is in the gene PRSS56, which has previously been linked to abnormally small eyes; one is in a gene that forms part of the extracellular matrix (LAMA2); two are in or near genes involved in the regeneration of 11-cis-retinal (RGR and RDH5); two are near genes known to be involved in the growth and guidance of retinal ganglion cells (ZIC2, SFRP1); and five are in or near genes involved in neuronal signaling or development. These novel findings point toward multiple genetic factors involved in the development of myopia and suggest that complex interactions between extracellular matrix remodeling, neuronal development, and visual signals from the retina may underlie the development of myopia in humans.

Macular Pigment Optical Density and Ocular Pulse Amplitude in Subjects with Different Axial Lengths and Refractive Errors.

BACKGROUND: The purpose of our study was to: (1) investigate the macular pigment optical density (MPOD) and ocular pulse amplitude (OPA) in subjects with different axial lengths (AL) and refractive errors (RE); (2) determine if there is a correlation between MPOD and OPA; and (3) evaluate whether MPOD and OPA depend on intraocular pressure (IOP). MATERIAL AND METHODS: This study included 140 eyes of 70 subjects - 17 men and 53 women, aged 18 to 29 years (mean: 22.5 years; SD=2.8). Every examined person underwent a thorough eye examination including: visual acuity, anterior segment and fundus examination, keratometry, auto-refractometry, and MPOD, OPA, AL, and IOP measurements. The obtained results were analyzed statistically using Statistica 10 software. P values of <0.05 were considered statistically significant. RESULTS: The following refractive errors were selected: emmetropia (34 eyes), hyperopia (18 eyes), low myopia (60 eyes), medium myopia (19 eyes), and high myopia (9 eyes). It has been established that the OPA increases with the rise in the spherical equivalents (SE) (Rs=+0.38, P<0.001), while the increase in AL correlates with the decrease of OPA (Rs=-0.40, P<0.001). The increase in IOP correlates with the rise in the OPA (Rs=+0.20, P<0.05). There were no significant correlations between IOP and SE or AL. CONCLUSIONS: (1) MPOD is not correlated with the OPA in subjects with different AL and RE; (2) OPA decreases with the rise of AL; (3) OPA decreases with the fall of the SE; and (4) OPA increases with the rise in IOP.