Assessment of conjunctival, episcleral and scleral thickness in healthy individuals using anterior segment optical coherence tomography

PURPOSE

To determine the thickness of the conjunctiva, episclera and sclera in healthy individuals using anterior segment optical coherence tomography (AS-OCT).

METHODS

We prospectively included 107 healthy individuals of different age groups (18-39 years, 40-54 years, 55-69 years and ≥70 years). For each eye, AS-OCT scans of four quadrants (temporal, nasal, superior and inferior) were acquired. The thickness of the conjunctiva, episclera and sclera was measured for each scan. In addition, the axial length of both eyes was measured, and general characteristics, including smoking, allergies and contact lens use, were collected.

RESULTS

The mean conjunctival thickness was significantly different between the nasal and superior quadrants (87 ± 30 μm vs. 77 ± 16 μm; p < 0.001), as well as the superior and inferior quadrants (77 ± 16 μm vs. 86 ± 19 μm; p = 0.001). The mean episcleral thickness was larger in the superior (174 ± 54 μm) and inferior (141 ± 43 μm) quadrants, compared to the nasal (83 ± 38 μm) and temporal quadrants (90 ± 44 μm). The mean scleral thickness of the inferior quadrant was the largest (596 ± 64 μm), followed by the nasal (567 ± 76 μm), temporal (516 ± 67 μm) and superior (467 ± 52 μm) quadrants (all p < 0.001). The averaged scleral thickness increased 0.96 μm per age year (0.41-1.47 μm, p < 0.001).

CONCLUSIONS

This study provides an assessment of the thickness of scleral and adjacent superficial layers in healthy individuals determined on AS-OCT, which could enable future research into the use of AS-OCT in diseases affecting the anterior eye wall.

Prevalence of Myopic Macular Features in Dutch Individuals of European Ancestry With High Myopia

Question

What is the prevalence of myopic macular degeneration in Dutch individuals of European ancestry with high myopia?

Findings

In this cross-sectional study of 626 individuals with European ancestry with high myopia, the prevalence of myopic macular degeneration was 25.9% and increased with older age, lower spherical equivalent of refractive error, and higher axial length.

Meaning

Myopic retinal features were frequent in this highly myopic study population, but not different than patients of Asian ancestry with similar risk profiles.

Importance

High myopia incidence and prevalence is increasing worldwide, and the visual burden caused by myopia is expected to rise accordingly. Studies investigating the occurrence of myopic complications in individuals of European ancestry with high myopia are scarce, hampering insights into the frequency of myopic retinal complications in European individuals and their visual burden.

Objective

To assess the frequency of myopic macular features in individuals of European ancestry with high myopia.

Design, Setting, and Participants

This cross-sectional analysis of the Dutch Myopia Study (MYST) and individuals with high myopia from the Rotterdam Study (RS) included 626 patients with high myopia (spherical equivalent of refractive error [SER] ≤−6 diopters [D] or axial length [AL] ≥26 mm) who underwent an extensive ophthalmic examination including multimodal retinal imaging. In addition to this combination of a population-based cohort study and mix-based high myopia study, a systematic literature review was also performed to compare findings with studies of individuals of Asian ancestry.

Exposures

High myopia, age, and AL.

Main Outcomes and Measures

Frequency of myopic macular and optic disc features: tessellated fundus, myopic macular degeneration (MMD), staphyloma, peripapillary intrachoroidal cavitation, peripapillary atrophy (PPA), and “plus” lesions (choroidal neovascularization, Fuchs spot, and lacquer cracks).

Results

The mean (SD) SER of the combined study population (MYST and RS) was −9.9 (3.2) D; the mean (SD) age was 51.4 (15.1) years, and 387 (61.8%) were women. The prevalence of MMD was 25.9% and increased with older age (P for trend <.001), lower SER (odds ratio [OR], 0.70; 95% CI, 0.65-0.76; P < .001), and higher AL (OR, 2.53; 95% CI, 2.13-3.06; P < .001). Choroidal neovascularization or Fuchs spot was present in 2.7% (n = 17), both lesions in 0.3% (n = 2), and lacquer cracks in 1.4% (n = 9). Staphyloma, PPA, and MMD were highly prevalent in visual impaired and blind eyes (frequency was 73.9% [20 of 27], 90.5% [19 of 21], and 63.0% [17 of 27] of unilateral blind eyes for MMD, staphyloma, and PPA, respectively). Seven previous studies in Asian populations reported a variable MMD frequency ranging from 8.3% to 64%, but frequencies were similar for comparable risk profiles based on age and SER.

Conclusions and Relevance

In this cross-sectional study of a highly myopic Dutch population of European ancestry, myopic retinal features were frequent; were associated with age, SER, and AL; and occurred in all visually severely impaired eyes. The absence of treatment options for most of these retinal complications emphasizes the need for effective strategies to prevent high myopia.

CAUSES AND CLINICAL MANIFESTATIONS OF MASQUERADE SYNDROMES IN INTRAOCULAR INFLAMMATORY DISEASES

OBJECTIVE

To identify the clinical characteristics and prevalence of neoplastic and nonneoplastic inflammatory masquerade syndromes (IMSs) in a tertiary center and determine the useful diagnostic tests.

METHODS

A retrospective cohort study of consecutive 1906 patients diagnosed with intraocular inflammatory disease.

RESULTS

Of all patients initially diagnosed with intraocular inflammatory disease, we identified 116 (6%) patients with noninflammatory causes (neoplastic IMSs in 36/116; 31% and nonneoplastic IMSs in 52/116; 45%). In addition, 26 patients (22%, 1.4% of all) had drug-induced uveitis and 2 (2%, 0.1% of all) had paraneoplastic uveitis. The large B-cell lymphoma was the most common neoplastic IMS (78%), and the major clinical features were presence of cells and floaters in the vitreous (69%) and chorioretinal lesions (33%). The causes of nonneoplastic IMSs included retinal vascular disorders (38%), hereditary retinal diseases (31%), and degenerative ocular disorders (19%). The common clinical manifestations consisted of chorioretinal scars (27%), small white-yellow retinal lesions (17%), and leaking vessels on fluorescein angiography (14%).

CONCLUSION

Noninflammatory causes were determined in 6% of a large population with initial diagnosis of intraocular inflammatory disease. Although neoplastic IMS was commonly characterized by vitreous cells and opacities, most common definitive diagnoses in nonneoplastic IMS encompassed diverse retinal disorders.

Enlargement of Geographic Atrophy From First Diagnosis to End of Life

Importance

Treatments for geographic atrophy (GA), a late stage of age-related macular degeneration (AMD), are currently under development. Understanding the natural course is needed for optimal trial design. Although enlargement rates of GA and visual acuity (VA) in the short term are known from clinical studies, knowledge of enlargement in the long term, life expectancy, and visual course is lacking.

Objective

To determine long-term enlargement of GA.

Design, Setting, and Participants

In this study, participant data were collected from 4 population-based cohort studies, with up to 25 years of follow-up and eye examinations at 5-year intervals: the Rotterdam Study cohorts 1, 2, and 3 and the Blue Mountains Eye Study. Data were collected from 1990 to 2015, and data were analyzed from January 2019 to November 2020.

Main Outcomes and Measures

Area of GA was measured pixel by pixel using all available imaging. Area enlargement and enlargement of the square root-transformed area, time until GA reached the central fovea, and time until death were assessed, and best-corrected VA, smoking status, macular lesions according to the Three Continent AMD Consortium classification, a modified version of the Wisconsin age-related maculopathy grading system, and AMD genetic variants were covariates in Spearman, Pearson, or Mann-Whitney analyses.

Results

Of 171 included patients, 106 (62.0%) were female, and the mean (SD) age at inclusion was 82.6 (7.1) years. A total of 147 of 242 eyes with GA (60.7%) were newly diagnosed in our study. The mean area of GA at first presentation was 3.74 mm2 (95% CI, 3.11-4.67). Enlargement rate varied widely between persons (0.02 to 4.05 mm2 per year), with a mean of 1.09 mm2 per year (95% CI, 0.89-1.30). Stage of AMD in the other eye was correlated with GA enlargement (Spearman ρ = 0.34; P = .01). Foveal involvement was already present in incident GA in 55 of 147 eyes (37.4%); 23 of 42 eyes (55%) developed this after a mean (range) period of 5.6 (3-12) years, and foveal involvement did not develop before death in 11 of 42 eyes (26%). After first diagnosis, 121 of 171 patients with GA (70.8%) died after a mean (SD) period of 6.4 (5.4) years. Visual function was visually impaired (less than 20/63) in 47 of 107 patients (43.9%) at last visit before death.

Conclusions and Relevance

In this study, enlargement of GA appeared to be highly variable in the general population. More than one-third of incident GA was foveal at first presentation; those with extrafoveal GA developed foveal GA after a mean of 5.6 years. Future intervention trials should focus on recruiting those patients who have a high chance of severe visual decline within their life expectancy.

Prevalence and Severity of Diabetic Retinopathy in Patients with Macular Telangiectasia Type 2

PURPOSE

To study the prevalence and severity of diabetic retinopathy (DR) in patients with macular telangiectasia type 2 (MacTel 2).

DESIGN

Retrospective case series.

PARTICIPANTS

Patients with a diagnosis of MacTel 2 treated at the Rotterdam Eye Hospital or Erasmus Medical Center between 2014 and 2018 were included.

METHODS

The following information was retrieved from patient files: demographics, history of diabetes mellitus and hypertension, presence of DR, and severity of DR, that is, mild, moderate, severe, or proliferative. Presence of diabetic macular edema (DME) was assessed using OCT.

MAIN OUTCOME MEASURES

Presence and severity of DR.

RESULTS

Two hundred six eyes of 103 patients were included. At the onset of MacTel 2, the mean age was 61 years (standard deviation [SD], 9.8 years) and 64 (62%) were women. Mean follow-up was 71 months (SD, 60 months). Diabetes mellitus type 2 was present in 50 patients (49%) and hypertension was present in 47 patients (46%). Mild DR was present in 22 eyes (11%), of which 14 eyes (7%) showed signs at baseline and 8 eyes (4%) showed signs at a later time during follow-up. Ten eyes (5%) demonstrated remission of mild DR during follow-up. Both eyes (1%) in 1 patient progressed to moderate DR. Severe DR, proliferative DR, and DME did not occur.

CONCLUSIONS

Although diabetes mellitus was highly prevalent among MacTel 2 patients, no patients showed severe or proliferative DR or DME. These findings suggest that MacTel 2 could have a protective effect on the progression of DR. We hypothesize that our results may be explained by the role of Müller cells in the development of MacTel 2 and DR, and therefore a link between both diseases warrants additional studies.

Current insights in the pathogenesis of scleritis

Scleritis is a sight-threatening inflammation characterized by severe pain and redness of the eye. It can cause blindness by severe complications like scleral and corneal necrosis, keratitis, and uveitis. The pathogenesis of scleritis is largely unknown due to a combination of the rarity of the disease, the little available human tissue-based research material, and the lack of animal models. The immune system is assumed to play a crucial role in the pathogenesis of scleritis. Multiple clues indicate probable antigenic stimuli in scleritis, and the involvement of matrix metalloproteinases in the destruction of scleral tissue. In this article we review the current insights into the pathogenesis of scleritis, and we suggest new hypotheses by implementing knowledge of systemic autoimmune disease pathogenesis. Understanding the pathogenesis of scleritis is crucial to improve the clinical management, as well as to find novel treatment modalities.

Comparing the Efficacy of Bevacizumab and Ranibizumab in Patients with Diabetic Macular Edema (BRDME): The BRDME Study, a Randomized Trial

PURPOSE

To generate conclusive evidence regarding the noninferiority of intravitreal bevacizumab compared with ranibizumab in patients with diabetic macular edema (DME).

DESIGN

Comparative, randomized, double-masked, multicenter, noninferiority clinical trial.

PARTICIPANTS

Eligible patients were older than 18 years, diagnosed with type 1 or type 2 diabetes mellitus, with glycosylated hemoglobin of less than 12%, central area thickness of more than 325 μm, and visual impairment from DME with a best-corrected visual acuity (BCVA) between 24 letters and 78 letters.

METHODS

From June 2012 through February 2018, a total of 170 participants were randomized to receive 6 monthly injections of either 1.25 mg bevacizumab (n = 86) or 0.5 mg ranibizumab (n = 84).

MAIN OUTCOME MEASURES

Primary outcome was change in BCVA from baseline to month 6 compared between the 2 treatment arms. The noninferiority margin was 3.5 letters.

RESULTS

The difference in mean BCVA between treatment arms was 1.8 letters in favor of ranibizumab after 6 months of follow-up; BCVA improved by 4.9±6.7 letters in the bevacizumab group and 6.7±8.7 letters in the ranibizumab group. The lower bound of the 2-sided 90% confidence interval (CI) was -3.626 letters, exceeding the noninferiority margin of 3.5 letters. Central area thickness decreased more with ranibizumab (138.2±114.3 μm) compared with bevacizumab (64.2±104.2 μm). In a post hoc subgroup analysis, participants with a worse BCVA at baseline (≤69 letters) improved by 6.7±7.0 letters with bevacizumab and 10.4±10.0 letters with ranibizumab, and central area thickness decreased significantly more in the ranibizumab arm of this subgroup compared with the bevacizumab arm. Participants with an initially better BCVA at baseline (≥70 letters) did not demonstrate differences in BCVA or OCT outcomes between treatment arms.

CONCLUSIONS

Based on change in BCVA from baseline to month 6, the noninferiority of 1.25 mg bevacizumab to 0.5 mg ranibizumab was not confirmed. Only the subgroup of patients with a lower BCVA at baseline showed better visual acuity and anatomic outcomes with ranibizumab. Our study confirmed the potential differential efficacy of anti-vascular endothelial growth factor agents in the treatment of DME as well as the difference in response between patient groups with different baseline visual acuities.

Growth in foetal life, infancy, and early childhood and the association with ocular biometry

PURPOSE

Ocular biometry varies within groups of emmetropic, hyperopic or myopic children. The aim of this study was to quantify the effect of foetal and infant growth on ocular biometry in early childhood, to determine the most important period for this association, and to examine genetic overlap with height and birth weight.

METHODS

5931 children (50.1% girls) from a population-based prospective birth cohort study underwent intra-uterine and infant growth measurements at second and third trimester, and from birth to 72 months. An ophthalmic examination including axial length (mm) and corneal radius of curvature (mm) was performed at 6 years of age. The associations between prenatal and postnatal growth variables and axial length and corneal radius of curvature were assessed with conditional linear regression analyses. Weighted genetic risk scores for birth weight and height were calculated and causality was tested with Mendelian randomisation.

RESULTS

Weight and length from mid-pregnancy to 2 years of age were most important prognostic factors for axial length and corneal radius of curvature at age 4.9-9 years (mean 6.2 years S.D. 0.5). For height (Standard deviation score), the association with axial length and corneal radius of curvature was highest for the measurement at 12 months (β 0.171 p < 0.001 and 0.070 p < 0.001). The genetic height and birth weight risk scores were both significantly associated with ocular biometry.

CONCLUSIONS

Larger neonates had longer axial length and greater corneal radius of curvature. Growth during pregnancy and 2 years postnatally is the most important period underlying this association and may be partly genetically determined by genes associated with height.

Progression characteristics of ellipsoid zone loss in macular telangiectasia type 2

PURPOSE

To investigate the progression characteristics of ellipsoid zone (EZ) loss in eyes with macular telangiectasia type 2 (MacTel) as reflected by area and linear measurements, and their relevance for visual acuity.

METHODS

Participants were selected from the MacTel Study cohort. Linear and area measurements of EZ loss were performed in Spectral-Domain Optical Coherence Tomograph (SD-OCT) volume scans. Progression characteristics and correlations between linear and area measurements were analysed using linear mixed effects models.

RESULTS

A total of 134 eyes of 70 patients were included (85 eyes with follow-up, mean 4.7 years, range: 1.4-8 years). Ellipsoid zone (EZ) loss significantly progressed at a mean annual increment of 0.057 mm² (p = 0.005). The progression rate was non-linear and interacted significantly with initial EZ lesion size indicating an exponential growth before reaching a plateau. There was a strong heterogeneity in area sizes between fellow eyes. EZ break length had a significant linear effect on EZ break area (b = 1.06, p < 0.001) and could predict it. The location of the EZ break had a significant impact on visual acuity.

CONCLUSION

Ellipsoid zone (EZ) loss in MacTel has a non-linear progression characteristic, and its rate depends on area size at baseline, which must be taken into account at sample selection in clinical trials. Our results show a good correlation of linear and area measures of EZ loss and a segregation of best-corrected visual acuity by EZ location, which may help routine clinical practice.

Intake of Vegetables, Fruit, and Fish is Beneficial for Age-Related Macular Degeneration

PURPOSE

What patients should eat to reduce their risk of age-related macular degeneration (AMD) is still unclear. We investigated the effect of a diet recommended by Health Councils on AMD.

DESIGN

Prospective population-based cohort study.

METHODS

Four thousand two hundred and two participants from the Rotterdam Study ≥55 years of age who were free of AMD at baseline were included and followed up for 9.1 ± 5.8 years. Incident AMD was graded on fundus photographs. Dietary data were collected using a validated 170-item food frequency questionnaire, and food intakes were categorized into food patterns based on guidelines from Health Councils. Associations with incident AMD were analyzed using Cox proportional hazards models that were adjusted for age, sex, total energy intake, smoking, body mass index, hypertension, education, and income.

RESULTS

Seven hundred fifty-four people developed incident AMD. Intake of the recommended amounts of vegetables (≥200 g/day), fruit (2×/day), and fish (2×/week) were 30.6%, 54.9%, and 12.5%, respectively. In particular, the intake of fish (2×/week) decreased the risk of incident AMD (hazard ratio 0.76 [95% confidence interval 0.60-0.97]). Intake of the recommended amounts of all 3 food groups was only 3.7%, but adherence to this pattern showed a further reduction of the risk of incident AMD (hazard ratio 0.58 [95% confidence interval 0.36-0.93]). Younger age, higher income, and not smoking were associated with this food pattern, but the risk-lowering effects remained significant after additional adjustment for these factors.

CONCLUSION

A diet of 200 grams per day of vegetables, fruit two times per day, and fish two times per week is associated with a significantly reduced risk of AMD.

Pimasertib-associated ophthalmological adverse events

PURPOSE

To analyse ophthalmological adverse events associated with mitogen-activated protein kinase kinase (MEK) inhibition with pimasertib treatment for metastatic cutaneous melanoma (CM).

METHODS

In this prospective observational, cohort-based, cross-sectional study, eight patients treated with the MEK inhibitor pimasertib received a complete ophthalmic examination. This included Early Treatment of Diabetic Retinopathy Study best-corrected visual acuity, visual field testing, colour vision testing, slit-lamp examination, applanation tonometry, indirect ophthalmoscopy, digital colour fundus photography and optical coherence tomography (OCT). In selected cases, fluorescein angiography was performed.

RESULTS

Serous subretinal fluid (SRF) developed in all patients, within a time frame of 9-27 days after the start of treatment. The fovea was involved in six of eight patients (75%). None of the patients with foveal SRF [excluding a patient who developed a bilateral retinal vein occlusion (RVO)] experienced visual symptoms. Subretinal fluid (SRF) decreased or resolved in all patients, despite continuation of study medication in six of eight patients (75%). Complaints in the CM patient (13%) consisted of experiencing a dark fleck in the inferior part of the visual field of the right eye 1 week after the start of treatment, due to an RVO. Subsequent intravitreal bevacizumab treatment resulted in functional and anatomical improvement.

CONCLUSION

Patients with metastatic CM who are treated with the MEK inhibitor pimasertib are at high risk of development of ocular adverse events including serous retinopathy and possibly RVO, stressing the need of adequate ophthalmological follow-up including OCT during administration of pimasertib, despite the fact that SRF generally does not lead to ophthalmological complaints.

Environmental Risk Factors Can Reduce Axial Length Elongation and Myopia Incidence in 6- to 9-Year-Old Children

PURPOSE

To identify risk factors for axial length (AL) elongation and incident school myopia.

DESIGN

Population-based prospective birth-cohort study.

PARTICIPANTS

Four thousand seven hundred thirty-four children examined at 6 and 9 years of age from the Generation R Study in Rotterdam, The Netherlands.

METHODS

Axial length and corneal radius (CR) were measured with an IOLMaster 500 and daily life activities and demographic characteristics were obtained by questionnaire. Three thousand three hundred sixty-two children (71%) were eligible for cycloplegic refractive error measurements. Linear regression models on AL elongation were used to create a risk score based on the regression coefficients resulting from environmental and ocular factors. The predictive value of the prediction score for myopia (≤-0.5 diopter) was estimated using receiver operating characteristic curves. To test if regression coefficients differed for baseline AL-to-CR ratio, interaction terms were calculated with baseline AL-to-CR ratio and environmental factors.

MAIN OUTCOME MEASURES

Axial length elongation and incident myopia.

RESULTS

From 6 to 9 years of age, average AL elongation was 0.21±0.009 mm/year and myopia developed in 223 of 2136 children (10.4%), leading to a myopia prevalence at 9 years of age of 12.0%. Seven parameters were associated independently (P < 0.05) with faster AL elongation: parental myopia, 1 or more books read per week, time spent reading, no participation in sports, non-European ethnicity, less time spent outdoors, and baseline AL-to-CR ratio. The discriminative accuracy for incident myopia based on these risk factors was 0.78. Axial length-to-CR ratio at baseline showed statistically significant interaction with number of books read per week (P < 0.01) and parental myopia (P < 0.01). Almost all predictors showed the highest association with AL elongation in the highest quartile of AL-to-CR ratio; incidental myopia in this group was 24% (124/513).

CONCLUSIONS

Determination of a risk score can help to identify school children at high risk of myopia. Our results suggest that behavioral changes can offer protection particularly in these children.

Thinner retinal layers are associated with changes in the visual pathway: A population-based study

Increasing evidence shows that thinner retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL), assessed on optical coherence tomography (OCT), are reflecting global brain atrophy. Yet, little is known on the relation of these layers with specific brain regions. Using voxel-based analysis, we aimed to unravel specific brain regions associated with these retinal layers. We included 2,235 persons (mean age: 67.3 years, 55% women) from the Rotterdam Study (2007-2012) who had gradable retinal OCT images and brain magnetic resonance imaging (MRI) scans, including diffusion tensor (DT) imaging. Thicknesses of peripapillary RNFL and perimacular GCL were measured using an automated segmentation algorithm. Voxel-based morphometry protocols were applied to process DT-MRI data. We investigated the association between retinal layer thickness with voxel-wise gray matter density and white matter microstructure by performing linear regression models. We found that thinner RNFL and GCL were associated with lower gray matter density in the visual cortex, and with lower fractional anisotropy and higher mean diffusivity in white matter tracts that are part of the optic radiation. Furthermore, thinner GCL was associated with lower gray matter density of the thalamus. Thinner RNFL and GCL are associated with gray and white matter changes in the visual pathway suggesting that retinal thinning on OCT may be specifically associated with changes in the visual pathway rather than with changes in the global brain. These findings may serve as a basis for understanding visual symptoms in elderly patients, patients with Alzheimer's disease, or patients with posterior cortical atrophy.

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.

Axial length growth and the risk of developing myopia in European children

PURPOSE

To generate percentile curves of axial length (AL) for European children, which can be used to estimate the risk of myopia in adulthood.

METHODS

A total of 12 386 participants from the population-based studies Generation R (Dutch children measured at both 6 and 9 years of age; N = 6934), the Avon Longitudinal Study of Parents and Children (ALSPAC) (British children 15 years of age; N = 2495) and the Rotterdam Study III (RS-III) (Dutch adults 57 years of age; N = 2957) contributed to this study. Axial length (AL) and corneal curvature data were available for all participants; objective cycloplegic refractive error was available only for the Dutch participants. We calculated a percentile score for each Dutch child at 6 and 9 years of age.

RESULTS

Mean (SD) AL was 22.36 (0.75) mm at 6 years, 23.10 (0.84) mm at 9 years, 23.41 (0.86) mm at 15 years and 23.67 (1.26) at adulthood. Axial length (AL) differences after the age of 15 occurred only in the upper 50%, with the highest difference within the 95th percentile and above. A total of 354 children showed accelerated axial growth and increased by more than 10 percentiles from age 6 to 9 years; 162 of these children (45.8%) were myopic at 9 years of age, compared to 4.8% (85/1781) for the children whose AL did not increase by more than 10 percentiles.

CONCLUSION

This study provides normative values for AL that can be used to monitor eye growth in European children. These results can help clinicians detect excessive eye growth at an early age, thereby facilitating decision-making with respect to interventions for preventing and/or controlling myopia.

Systemic and Ocular Determinants of Peripapillary Retinal Nerve Fiber Layer Thickness Measurements in the European Eye Epidemiology (E3) Population

PURPOSE

To investigate systemic and ocular determinants of peripapillary retinal nerve fiber layer thickness (pRNFLT) in the European population.

DESIGN

Cross-sectional meta-analysis.

PARTICIPANTS

A total of 16 084 European adults from 8 cohort studies (mean age range, 56.9±12.3-82.1±4.2 years) of the European Eye Epidemiology (E3) consortium.

METHODS

We examined associations with pRNFLT measured by spectral-domain OCT in each study using multivariable linear regression and pooled results using random effects meta-analysis.

MAIN OUTCOME MEASURES

Determinants of pRNFLT.

RESULTS

Mean pRNFLT ranged from 86.8±21.4 μm in the Rotterdam Study I to 104.7±12.5 μm in the Rotterdam Study III. We found the following factors to be associated with reduced pRNFLT: Older age (β = -0.38 μm/year; 95% confidence interval [CI], -0.57 to -0.18), higher intraocular pressure (IOP) (β = -0.36 μm/mmHg; 95% CI, -0.56 to -0.15), visual impairment (β = -5.50 μm; 95% CI, -9.37 to -1.64), and history of systemic hypertension (β = -0.54 μm; 95% CI, -1.01 to -0.07) and stroke (β = -1.94 μm; 95% CI, -3.17 to -0.72). A suggestive, albeit nonsignificant, association was observed for dementia (β = -3.11 μm; 95% CI, -6.22 to 0.01). Higher pRNFLT was associated with more hyperopic spherical equivalent (β = 1.39 μm/diopter; 95% CI, 1.19-1.59) and smoking (β = 1.53 μm; 95% CI, 1.00-2.06 for current smokers compared with never-smokers).

CONCLUSIONS

In addition to previously described determinants such as age and refraction, we found that systemic vascular and neurovascular diseases were associated with reduced pRNFLT. These may be of clinical relevance, especially in glaucoma monitoring of patients with newly occurring vascular comorbidities.

Whole-Exome Sequencing in Age-Related Macular Degeneration Identifies Rare Variants in COL8A1, a Component of Bruch's Membrane

PURPOSE

Genome-wide association studies and targeted sequencing studies of candidate genes have identified common and rare variants that are associated with age-related macular degeneration (AMD). Whole-exome sequencing (WES) studies allow a more comprehensive analysis of rare coding variants across all genes of the genome and will contribute to a better understanding of the underlying disease mechanisms. To date, the number of WES studies in AMD case-control cohorts remains scarce and sample sizes are limited. To scrutinize the role of rare protein-altering variants in AMD cause, we performed the largest WES study in AMD to date in a large European cohort consisting of 1125 AMD patients and 1361 control participants.

DESIGN

Genome-wide case-control association study of WES data.

PARTICIPANTS

One thousand one hundred twenty-five AMD patients and 1361 control participants.

METHODS

A single variant association test of WES data was performed to detect variants that are associated individually with AMD. The cumulative effect of multiple rare variants with 1 gene was analyzed using a gene-based CMC burden test. Immunohistochemistry was performed to determine the localization of the Col8a1 protein in mouse eyes.

MAIN OUTCOME MEASURES

Genetic variants associated with AMD.

RESULTS

We detected significantly more rare protein-altering variants in the COL8A1 gene in patients (22/2250 alleles [1.0%]) than in control participants (11/2722 alleles [0.4%]; P = 7.07×10^-5). The association of rare variants in the COL8A1 gene is independent of the common intergenic variant (rs140647181) near the COL8A1 gene previously associated with AMD. We demonstrated that the Col8a1 protein localizes at Bruch's membrane.

CONCLUSIONS

This study supported a role for protein-altering variants in the COL8A1 gene in AMD pathogenesis. We demonstrated the presence of Col8a1 in Bruch's membrane, further supporting the role of COL8A1 variants in AMD pathogenesis. Protein-altering variants in COL8A1 may alter the integrity of Bruch's membrane, contributing to the accumulation of drusen and the development of AMD.

Antiplatelet and Anticoagulant Drugs Do Not Affect Visual Outcome in Neovascular Age-Related Macular Degeneration in the BRAMD Trial

PURPOSE

To determine if use of antiplatelet or anticoagulant (AP/AC) medication influences visual acuity in patients with active neovascular age-related macular degeneration (N-AMD).

DESIGN

Retrospective analysis of data from a randomized controlled trial.

METHODS

Setting: Multicenter.

STUDY POPULATION

Total of 330 patients with active N-AMD from the BRAMD study, a comparative trial between bevacizumab and ranibizumab in the Netherlands.

OBSERVATION PROCEDURES

Patients underwent an extensive ophthalmic examination. Visual acuity was categorized into functional vision (best-corrected visual acuity [BCVA] ≥ 0.5), visual impairment (BCVA < 0.5), and severe visual impairment (BCVA < 0.3). Fundus photographs were graded for presence of retinal or subretinal hemorrhages. Information on AP/AC medication was obtained through interview. Logistic regression analysis was used to determine associations between AP/AC medication and outcomes. Frequency of hemorrhages in users and non-users stratified for visual acuity categories was analyzed with ANCOVA.

MAIN OUTCOME MEASURES

BCVA and presence of hemorrhages.

RESULTS

In total, 40.9% of the patients used AP/AC medication, of which 73.3% was aspirin. AP/AC use was not associated with visual impairment (adjusted odds ratio [OR] 0.79; 95% confidence interval [CI] 0.43-1.44) or severe visual impairment (adjusted OR 0.75; 95% CI 0.40-1.43). Patients on AP/AC presented with comparable frequencies of hemorrhages (27% vs 32%, P = .32, respectively). Similar results were found when analyses were restricted to aspirin users only.

CONCLUSION

In our study, use of AP/AC medication was associated neither with visual decline nor with the occurrence of hemorrhages in patients with active N-AMD.

A genome-wide association study of corneal astigmatism: The CREAM Consortium

Purpose

To identify genes and genetic markers associated with corneal astigmatism.

Methods

A meta-analysis of genome-wide association studies (GWASs) of corneal astigmatism undertaken for 14 European ancestry (n=22,250) and 8 Asian ancestry (n=9,120) cohorts was performed by the Consortium for Refractive Error and Myopia. Cases were defined as having >0.75 diopters of corneal astigmatism. Subsequent gene-based and gene-set analyses of the meta-analyzed results of European ancestry cohorts were performed using VEGAS2 and MAGMA software. Additionally, estimates of single nucleotide polymorphism (SNP)-based heritability for corneal and refractive astigmatism and the spherical equivalent were calculated for Europeans using LD score regression.

Results

The meta-analysis of all cohorts identified a genome-wide significant locus near the platelet-derived growth factor receptor alpha (PDGFRA) gene: top SNP: rs7673984, odds ratio=1.12 (95% CI:1.08-1.16), p=5.55×10^-9. No other genome-wide significant loci were identified in the combined analysis or European/Asian ancestry-specific analyses. Gene-based analysis identified three novel candidate genes for corneal astigmatism in Europeans-claudin-7 (CLDN7), acid phosphatase 2, lysosomal (ACP2), and TNF alpha-induced protein 8 like 3 (TNFAIP8L3).

Conclusions

In addition to replicating a previously identified genome-wide significant locus for corneal astigmatism near the PDGFRA gene, gene-based analysis identified three novel candidate genes, CLDN7, ACP2, and TNFAIP8L3, that warrant further investigation to understand their role in the pathogenesis of corneal astigmatism. The much lower number of genetic variants and genes demonstrating an association with corneal astigmatism compared to published spherical equivalent GWAS analyses suggest a greater influence of rare genetic variants, non-additive genetic effects, or environmental factors in the development of astigmatism.

Joint Contribution of Genetic Susceptibility and Modifiable Factors to the Progression of Age-Related Macular Degeneration over 10 Years: The Three Continent AMD Consortium Report

PURPOSE

To assess joint effects of genetic and modifiable factors on the 10-year progression of age-related macular degeneration (AMD).

DESIGN

Individual and pooled data analyses of 2 population-based cohorts.

PARTICIPANTS

Blue Mountains Eye Study (BMES) and Rotterdam Study (RS) participants (n = 835).

METHODS

Participants of the BMES and RS were followed up over 10 years or more. At baseline and follow-up visits, interviews using questionnaires and eye examinations with retinal photography were performed. Age-related macular degeneration was assessed by trained photographic graders and verified by retinal specialists. Genetic susceptibility to AMD meant carrying 2 or more risk alleles of the CFH or ARMS2 SNPs, or both (rs1061170 and rs10490924), relative to 0 or 1 risk allele. Discrete logistic regression models were used to investigate the joint associations of genetic susceptibility and either smoking, fish consumption, dietary intake of lutein-zeaxanthin, or combined environmental risk scores from the 3 modifiable factors with the risk of AMD progression. Odds ratios (ORs) with 95% confidence intervals (CIs) and synergy indexes are reported.

MAIN OUTCOME MEASURE

Ten-year progression of AMD, categorized as any (≥1 step) or 2-step (≥2 steps) progression on the Three Continent AMD Consortium 5-step severity scale.

RESULTS

Older age, the presence of AMD genetic susceptibility, and baseline AMD status were associated strongly with AMD progression (P < 0.0001). In analyses of pooled data, each additional score from the combined environmental risk scores was associated with an increased risk of 2-step progression over 10 years (OR, 1.26; 95% CI, 1.02-1.56). The copresence of AMD genetic susceptibility and combined risk score of 3 or more was associated with a substantially higher risk of 2-step progression compared with the presence of either factor alone. There was a significant synergistic effect (OR, 4.14; 95% CI, 1.07-15.95) and interaction (P = 0.025) between genetic susceptibility and environmental risk score of 3 or more.

CONCLUSIONS

Among persons with AMD genetic susceptibility and pre-existing early AMD lesions, presenting with high environmental risk scores from 3 modifiable factors (smoking, infrequent consumption of fish, low lutein-zeaxanthin intake) were associated with an increased risk of 2-step progression over 10 years.

Prevalence of Age-Related Macular Degeneration in Europe: The Past and the Future

Purpose

Age-related macular degeneration (AMD) is a frequent, complex disorder in elderly of European ancestry. Risk profiles and treatment options have changed considerably over the years, which may have affected disease prevalence and outcome. We determined the prevalence of early and late AMD in Europe from 1990 to 2013 using the European Eye Epidemiology (E3) consortium, and made projections for the future.

Design

Meta-analysis of prevalence data.

Participants

A total of 42 080 individuals 40 years of age and older participating in 14 population-based cohorts from 10 countries in Europe.

Methods

AMD was diagnosed based on fundus photographs using the Rotterdam Classification. Prevalence of early and late AMD was calculated using random-effects meta-analysis stratified for age, birth cohort, gender, geographic region, and time period of the study. Best-corrected visual acuity (BCVA) was compared between late AMD subtypes; geographic atrophy (GA) and choroidal neovascularization (CNV).

Main Outcome Measures

Prevalence of early and late AMD, BCVA, and number of AMD cases.

Results

Prevalence of early AMD increased from 3.5% (95% confidence interval [CI] 2.1%–5.0%) in those aged 55–59 years to 17.6% (95% CI 13.6%–21.5%) in those aged ≥85 years; for late AMD these figures were 0.1% (95% CI 0.04%–0.3%) and 9.8% (95% CI 6.3%–13.3%), respectively. We observed a decreasing prevalence of late AMD after 2006, which became most prominent after age 70. Prevalences were similar for gender across all age groups except for late AMD in the oldest age category, and a trend was found showing a higher prevalence of CNV in Northern Europe. After 2006, fewer eyes and fewer ≥80-year-old subjects with CNV were visually impaired (P = 0.016). Projections of AMD showed an almost doubling of affected persons despite a decreasing prevalence. By 2040, the number of individuals in Europe with early AMD will range between 14.9 and 21.5 million, and for late AMD between 3.9 and 4.8 million.

Conclusion

We observed a decreasing prevalence of AMD and an improvement in visual acuity in CNV occuring over the past 2 decades in Europe. Healthier lifestyles and implementation of anti–vascular endothelial growth factor treatment are the most likely explanations. Nevertheless, the numbers of affected subjects will increase considerably in the next 2 decades. AMD continues to remain a significant public health problem among Europeans.

Incidence of glaucomatous visual field loss after two decades of follow-up: the Rotterdam Study

To determine the incidence of glaucomatous visual field loss (GVFL) two decades after the start of the Rotterdam Study, and to compare known risk factors for open-angle glaucoma (OAG) between different clinical manifestations of OAG. Of 6806 participants aged 55 years and older from the population-based Rotterdam Study, 3939 underwent visual field testing at baseline and at least one follow-up round. The ophthalmic examinations included optic disc assessment and measurements of intraocular pressure (IOP), refractive error, diastolic blood pressure (DBP), and height and weight. The incidence rate of GVFL was calculated. Associations with the risk factors age, gender, baseline IOP, family history, myopia, DBP, and body-mass index [BMI] were assessed using Cox regression, with different clinical manifestations of OAG as outcome measure (glaucomatous optic neuropathy (GON), GVFL, GVFL and GON, GVFL without GON, and GON without GVFL). Median follow-up was 11.1 (IQR 6.8–17.2; range 5.0–20.3) years. The incidence rate of GVFL was 2.9 (95% confidence interval 2.4–3.4) per 1000 person years (140 cases with incident GVFL in one (n = 113) or both (n = 27) eyes). Baseline IOP and age were significantly associated with all OAG outcomes (all p < 0.001); BMI showed a non-significant protective effect in all outcomes (p = 0.01 to p = 0.09). Gender, myopia, and DBP were not associated with any outcome. Our study provides an estimate of the long-term incidence of GVFL in a predominantly white population. The development of GVFL was strongly associated with baseline IOP and age. Risk factor profiles were similar for the different outcomes.

Association of Axial Length With Risk of Uncorrectable Visual Impairment for Europeans With Myopia

Importance

Myopia (ie, nearsightedness) is becoming the most common eye disorder to cause blindness in younger persons in many parts of the world. Visual impairment due to myopia is associated with structural changes of the retina and the globe because of elongation of the eye axis. How axial length-a sum of the anterior chamber depth, lens thickness, and vitreous chamber depth-and myopia relate to the development of visual impairment over time is unknown.

Objectives

To evaluate the association between axial length, spherical equivalent, and the risk of visual impairment and to make projections of visual impairment for regions with high prevalence rates.

Design, Setting, and Participants

This cross-sectional study uses population-based data from the Rotterdam Study I (1990 to 1993), II (2000 to 2002), and III (2006 to 2008) and the Erasmus Rucphen Family Study (2002 to 2005) as well as case-control data from the Myopia Study (2010 to 2012) from the Netherlands. In total, 15 404 individuals with data on spherical equivalent and 9074 individuals with data on axial length were included in the study; right eyes were used for analyses. Data were analyzed from September 2014 to May 2016.

Main Outcomes and Measures

Visual impairment and blindness (defined according to the World Health Organization criteria as a visual acuity less than 0.3) and predicted rates of visual impairment specifically for persons with myopia.

Results

Of the 15 693 individuals included in this study, the mean (SD) age was 61.3 (11.4) years, and 8961 (57.1%) were female. Axial length ranged from 15.3 to 37.8 mm; 819 individuals had an axial length of 26 mm or greater. Spherical equivalent ranged from -25 to +14 diopters; 796 persons had high myopia (ie, a spherical equivalent of -6 diopters or less). The prevalence of visual impairment varied from 1.0% to 4.1% in the population-based studies, was 5.4% in the Myopia Study, and was 0.3% in controls. The prevalence of visual impairment rose with increasing axial length and spherical equivalent, with a cumulative incidence (SE) of visual impairment of 3.8% (1.3) for participants aged 75 years with an axial length of 24 to less than 26 mm and greater than 90% (8.1) with an axial length of 30 mm or greater. The cumulative risk (SE) of visual impairment was 5.7% (1.3) for participants aged 60 years and 39% (4.9) for those aged 75 years with a spherical equivalent of -6 diopters or less. Projections of these data suggest that visual impairment will increase 7- to 13-fold by 2055 in high-risk areas.

Conclusions and Relevance

This study demonstrated that visual impairment is associated with axial length and spherical equivalent and may be unavoidable at the most extreme values in this population. Developing strategies to prevent the development of myopia and its complications could help to avoid an increase of visual impairment in the working-age population.

Novel quantitative pigmentation phenotyping enhances genetic association, epistasis, and prediction of human eye colour

Success of genetic association and the prediction of phenotypic traits from DNA are known to depend on the accuracy of phenotype characterization, amongst other parameters. To overcome limitations in the characterization of human iris pigmentation, we introduce a fully automated approach that specifies the areal proportions proposed to represent differing pigmentation types, such as pheomelanin, eumelanin, and non-pigmented areas within the iris. We demonstrate the utility of this approach using high-resolution digital eye imagery and genotype data from 12 selected SNPs from over 3000 European samples of seven populations that are part of the EUREYE study. In comparison to previous quantification approaches, (1) we achieved an overall improvement in eye colour phenotyping, which provides a better separation of manually defined eye colour categories. (2) Single nucleotide polymorphisms (SNPs) known to be involved in human eye colour variation showed stronger associations with our approach. (3) We found new and confirmed previously noted SNP-SNP interactions. (4) We increased SNP-based prediction accuracy of quantitative eye colour. Our findings exemplify that precise quantification using the perceived biological basis of pigmentation leads to enhanced genetic association and prediction of eye colour. We expect our approach to deliver new pigmentation genes when applied to genome-wide association testing.

Five-year progression of unilateral age-related macular degeneration to bilateral involvement: the Three Continent AMD Consortium report

PURPOSE

To assess the 5-year progression from unilateral to bilateral age-related macular degeneration (AMD) and associated risk factors.

DESIGN

Pooled data analyses of three prospective population-based cohorts, the Blue Mountains Eye Study, Beaver Dam Eye Study and Rotterdam Study.

METHODS

Retinal photography and interview with comprehensive questionnaires were conducted at each visit of three studies. AMD was assessed following the modified Wisconsin AMD grading protocol. Progression to bilateral any (early and late) or late AMD was assessed among participants with unilateral involvement only. Factors associated with the progression were assessed using logistic regression models while simultaneously adjusting for other significant risk factors.

RESULTS

In any 5-year duration, 19-28% of unilateral any AMD cases became bilateral and 27-68% of unilateral late AMD became bilateral. Factors associated with the progression to bilateral involvement of any AMD were age (per year increase, adjusted OR 1.07), carrying risk alleles of the complement factor H and age-related maculopathy susceptibility 2 genes (compared with none, OR 1.76 for 1 risk allele and OR 3.34 for 2+ risk alleles), smoking (compared with non-smokers, OR 1.64 for past and OR 1.67 for current smokers), and the presence of large drusen area or retinal pigmentary abnormalities in the first eye.

CONCLUSION

One in four to one in five unilateral any AMD cases, and up to one in two unilateral late AMD cases, progressed to bilateral in 5 years. Known AMD risk factors, including smoking, are significantly associated with the progression to bilateral involvement.

New insights into the genetics of primary open-angle glaucoma based on meta-analyses of intraocular pressure and optic disc characteristics

Primary open-angle glaucoma (POAG), the most common optic neuropathy, is a heritable disease. Siblings of POAG cases have a ten-fold increased risk of developing the disease. Intraocular pressure (IOP) and optic nerve head characteristics are used clinically to predict POAG risk. We conducted a genome-wide association meta-analysis of IOP and optic disc parameters and validated our findings in multiple sets of POAG cases and controls. Using imputation to the 1000 genomes (1000G) reference set, we identified 9 new genomic regions associated with vertical cup-disc ratio (VCDR) and 1 new region associated with IOP. Additionally, we found 5 novel loci for optic nerve cup area and 6 for disc area. Previously it was assumed that genetic variation influenced POAG either through IOP or via changes to the optic nerve head; here we present evidence that some genomic regions affect both IOP and the disc parameters. We characterized the effect of the novel loci through pathway analysis and found that pathways involved are not entirely distinct as assumed so far. Further, we identified a novel association between CDKN1A and POAG. Using a zebrafish model we show that six6b (associated with POAG and optic nerve head variation) alters the expression of cdkn1a. In summary, we have identified several novel genes influencing the major clinical risk predictors of POAG and showed that genetic variation in CDKN1A is important in POAG risk.

Automated Segmentability Index for Layer Segmentation of Macular SD-OCT Images

PURPOSE

To automatically identify which spectral-domain optical coherence tomography (SD-OCT) scans will provide reliable automated layer segmentations for more accurate layer thickness analyses in population studies.

METHODS

Six hundred ninety macular SD-OCT image volumes (6.0 × 6.0 × 2.3 mm³) were obtained from one eyes of 690 subjects (74.6 ± 9.7 [mean ± SD] years, 37.8% of males) randomly selected from the population-based Rotterdam Study. The dataset consisted of 420 OCT volumes with successful automated retinal nerve fiber layer (RNFL) segmentations obtained from our previously reported graph-based segmentation method and 270 volumes with failed segmentations. To evaluate the reliability of the layer segmentations, we have developed a new metric, segmentability index SI, which is obtained from a random forest regressor based on 12 features using OCT voxel intensities, edge-based costs, and on-surface costs. The SI was compared with well-known quality indices, quality index (QI), and maximum tissue contrast index (mTCI), using receiver operating characteristic (ROC) analysis.

RESULTS

The 95% confidence interval (CI) and the area under the curve (AUC) for the QI are 0.621 to 0.805 with AUC 0.713, for the mTCI 0.673 to 0.838 with AUC 0.756, and for the SI 0.784 to 0.920 with AUC 0.852. The SI AUC is significantly larger than either the QI or mTCI AUC (P < 0.01).

CONCLUSIONS

The segmentability index SI is well suited to identify SD-OCT scans for which successful automated intraretinal layer segmentations can be expected.

TRANSLATIONAL RELEVANCE

Interpreting the quantification of SD-OCT images requires the underlying segmentation to be reliable, but standard SD-OCT quality metrics do not predict which segmentations are reliable and which are not. The segmentability index SI presented in this study does allow reliable segmentations to be identified, which is important for more accurate layer thickness analyses in research and population studies.

Meta-analysis of gene-environment-wide association scans accounting for education level identifies additional loci for refractive error

Myopia is the most common human eye disorder and it results from complex genetic and environmental causes. The rapidly increasing prevalence of myopia poses a major public health challenge. Here, the CREAM consortium performs a joint meta-analysis to test single-nucleotide polymorphism (SNP) main effects and SNP × education interaction effects on refractive error in 40,036 adults from 25 studies of European ancestry and 10,315 adults from 9 studies of Asian ancestry. In European ancestry individuals, we identify six novel loci (FAM150B-ACP1, LINC00340, FBN1, DIS3L-MAP2K1, ARID2-SNAT1 and SLC14A2) associated with refractive error. In Asian populations, three genome-wide significant loci AREG, GABRR1 and PDE10A also exhibit strong interactions with education (P<8.5 × 10(-5)), whereas the interactions are less evident in Europeans. The discovery of these loci represents an important advance in understanding how gene and environment interactions contribute to the heterogeneity of myopia.

Low serum vitamin D is associated with axial length and risk of myopia in young children

The aim of the study was to investigate the relationship between serum 25(OH)D levels and axial length (AL) and myopia in 6-year-old children. A total of 2666 children aged 6 years participating in the birth-cohort study Generation R underwent a stepwise eye examination. First, presenting visual acuity (VA) and AL were performed. Second, automated cycloplegic refraction was measured if LogMAR VA > 0.1. Serum 25-hydroxyvitamin D [25(OH)D] was determined from blood using liquid chromatography/tandem mass spectrometry. Vitamin D related SNPs were determined with a SNP array; outdoor exposure was assessed by questionnaire. The relationships between 25(OH)D and AL or myopia were investigated using linear and logistic regression analysis. Average 25(OH)D concentration was 68.8 nmol/L (SD ± 27.5; range 4–211); average AL 22.35 mm (SD ± 0.7; range 19.2–25.3); and prevalence of myopia 2.3 % (n = 62). After adjustment for covariates, 25(OH)D concentration (per 25 nmol/L) was inversely associated with AL (β −0.043; P < 0.01), and after additional adjusting for time spent outdoors (β −0.038; P < 0.01). Associations were not different between European and non-European children (β −0.037 and β −0.039 respectively). Risk of myopia (per 25 nmol/L) was OR 0.65 (95 % CI 0.46–0.92). None of the 25(OH)D related SNPs showed an association with AL or myopia. Lower 25(OH)D concentration in serum was associated with longer AL and a higher risk of myopia in these young children. This effect appeared independent of outdoor exposure and may suggest a more direct role for 25(OH)D in myopia pathogenesis.

Validity of Automated Choroidal Segmentation in SS-OCT and SD-OCT

PURPOSE

To evaluate the validity of a novel fully automated three-dimensional (3D) method capable of segmenting the choroid from two different optical coherence tomography scanners: swept-source OCT (SS-OCT) and spectral-domain OCT (SD-OCT).

METHODS

One hundred eight subjects were imaged using SS-OCT and SD-OCT. A 3D method was used to segment the choroid and quantify the choroidal thickness along each A-scan. The segmented choroidal posterior boundary was evaluated by comparing to manual segmentation. Differences were assessed to test the agreement between segmentation results of the same subject. Choroidal thickness was defined as the Euclidian distance between Bruch's membrane and the choroidal posterior boundary, and reproducibility was analyzed using automatically and manually determined choroidal thicknesses.

RESULTS

For SS-OCT, the average choroidal thickness of the entire 6- by 6-mm2 macular region was 219.5 μm (95% confidence interval [CI], 204.9-234.2 μm), and for SD-OCT it was 209.5 μm (95% CI, 197.9-221.0 μm). The agreement between automated and manual segmentations was high: Average relative difference was less than 5 μm, and average absolute difference was less than 15 μm. Reproducibility of choroidal thickness between repeated SS-OCT scans was high (coefficient of variation [CV] of 3.3%, intraclass correlation coefficient [ICC] of 0.98), and differences between SS-OCT and SD-OCT results were small (CV of 11.0%, ICC of 0.73).

CONCLUSIONS

We have developed a fully automated 3D method for segmenting the choroid and quantifying choroidal thickness along each A-scan. The method yielded high validity. Our method can be used reliably to study local choroidal changes and may improve the diagnosis and management of patients with ocular diseases in which the choroid is affected.

Comparing the effectiveness and costs of Bevacizumab to Ranibizumab in patients with Diabetic Macular Edema: a randomized clinical trial (the BRDME study)

Background

The effectiveness of ranibizumab in the treatment of diabetic macular edema has been proven with large clinical trials. For bevacizumab only two clinical trials have been published and a head-to-head comparison is lacking to date. However, if proved non-inferior to ranibizumab, use of the off-label bevacizumab could reduce costs enormously without a loss in visual acuity. A cost-effectiveness study has been designed to substantiate this hypothesis.

Aim

To compare the effectiveness and costs of 1.25 mg of bevacizumab to 0.5 mg ranibizumab given as monthly intravitreal injections during 6 months in patients with diabetic macular edema. It is hypothesized that bevacizumab is non-inferior to ranibizumab regarding its effectiveness.

Design

This is a randomized, controlled, double masked, clinical trial in 246 patients in seven academic trial centres in The Netherlands.

Outcomes

The primary outcome measure is the change in best-corrected visual acuity (BCVA) in the study eye from baseline to month 6. Secondary outcomes are the proportions of patients with a gain or loss of 15 letters or more or a BCVA of 20/40 or more at 6 months, the change in leakage on fluorescein angiography and the change in foveal thickness by optical coherence tomography at 6 months, the number of adverse events in 6 months, and the costs per quality adjusted life-year of the two treatments.

WNT10A exonic variant increases the risk of keratoconus by decreasing corneal thickness

Keratoconus is a degenerative eye condition which results from thinning of the cornea and causes vision distortion. Treatments such as ultraviolet (UV) cross-linking have proved effective for management of keratoconus when performed in early stages of the disease. The central corneal thickness (CCT) is a highly heritable endophenotype of keratoconus, and it is estimated that up to 95% of its phenotypic variance is due to genetics. Genome-wide association efforts of CCT have identified common variants (i.e. minor allele frequency (MAF) >5%). However, these studies typically ignore the large set of exonic variants whose MAF is usually low. In this study, we performed a CCT exome-wide association analysis in a sample of 1029 individuals from a population-based study in Western Australia. We identified a genome-wide significant exonic variant rs121908120 (P = 6.63 × 10(-10)) in WNT10A. This gene is 437 kb from a gene previously associated with CCT (USP37). We showed in a conditional analysis that the WNT10A variant completely accounts for the signal previously seen at USP37. We replicated our finding in independent samples from the Brisbane Adolescent Twin Study, Twin Eye Study in Tasmania and the Rotterdam Study. Further, we genotyped rs121908120 in 621 keratoconus cases and compared the frequency to a sample of 1680 unscreened controls from the Queensland Twin Registry. We found that rs121908120 increases the risk of keratoconus two times (odds ratio 2.03, P = 5.41 × 10(-5)).

Increasing Prevalence of Myopia in Europe and the Impact of Education

Purpose

To investigate whether myopia is becoming more common across Europe and explore whether increasing education levels, an important environmental risk factor for myopia, might explain any temporal trend.

Design

Meta-analysis of population-based, cross-sectional studies from the European Eye Epidemiology (E³) Consortium.

Participants

The E³ Consortium is a collaborative network of epidemiological studies of common eye diseases in adults across Europe. Refractive data were available for 61 946 participants from 15 population-based studies performed between 1990 and 2013; participants had a range of median ages from 44 to 78 years.

Methods

Noncycloplegic refraction, year of birth, and highest educational level achieved were obtained for all participants. Myopia was defined as a mean spherical equivalent ≤−0.75 diopters. A random-effects meta-analysis of age-specific myopia prevalence was performed, with sequential analyses stratified by year of birth and highest level of educational attainment.

Main Outcome Measures

Variation in age-specific myopia prevalence for differing years of birth and educational level.

Results

There was a significant cohort effect for increasing myopia prevalence across more recent birth decades; age-standardized myopia prevalence increased from 17.8% (95% confidence interval [CI], 17.6–18.1) to 23.5% (95% CI, 23.2–23.7) in those born between 1910 and 1939 compared with 1940 and 1979 (P = 0.03). Education was significantly associated with myopia; for those completing primary, secondary, and higher education, the age-standardized prevalences were 25.4% (CI, 25.0–25.8), 29.1% (CI, 28.8–29.5), and 36.6% (CI, 36.1–37.2), respectively. Although more recent birth cohorts were more educated, this did not fully explain the cohort effect. Compared with the reference risk of participants born in the 1920s with only primary education, higher education or being born in the 1960s doubled the myopia prevalence ratio–2.43 (CI, 1.26–4.17) and 2.62 (CI, 1.31–5.00), respectively—whereas individuals born in the 1960s and completing higher education had approximately 4 times the reference risk: a prevalence ratio of 3.76 (CI, 2.21–6.57).

Conclusions

Myopia is becoming more common in Europe; although education levels have increased and are associated with myopia, higher education seems to be an additive rather than explanatory factor. Increasing levels of myopia carry significant clinical and economic implications, with more people at risk of the sight-threatening complications associated with high myopia.

Thyroid function and age-related macular degeneration: a prospective population-based cohort study--the Rotterdam Study

BACKGROUND

In animal models, lack of thyroid hormone is associated with cone photoreceptor preservation, while administration of high doses of active thyroid hormone leads to deterioration. The association between thyroid function and age-related macular degeneration (AMD) has not been investigated in the general population.

METHODS

Participants of age ≥ 55 years from the Rotterdam Study with thyroid-stimulating hormone (TSH) and/or free thyroxine (FT4) measurements and AMD assessment were included. We conducted age- and sex-adjusted Cox proportional hazards models to explore the association of TSH or FT4 with AMD, in the full range and in those with TSH (0.4-4.0 mIU/L) and/or FT4 in normal range (11-25 pmol/L). Cox proportional hazards models were performed for the association of TSH or FT4 with retinal pigment alterations (RPA), as an early marker of retinal changes. Multivariable models additionally included cardiovascular risk factors and thyroid peroxidase antibodies positivity. We also performed stratification by age and sex. A bidirectional look-up in genome-wide association study (GWAS) data for thyroid parameters and AMD was performed. Single nucleotide polymorphisms (SNPs) that are significantly associated with both phenotypes were identified.

RESULTS

We included 5,573 participants with a median follow-up of 6.9 years (interquartile range 4.4-10.8 years). During follow-up 805 people developed AMD. TSH levels were not associated with increased risk of AMD. Within normal range of FT4, participants in the highest FT4 quintile had a 1.34-fold increased risk of developing AMD, compared to individuals in the middle group (95% confidence interval [CI] 1.07-1.66). Higher FT4 values in the full range were associated with a higher risk of AMD (hazard ratio 1.04, CI, 1.01-1.06 per 1 pmol/L increase). Higher FT4 levels were similarly associated with a higher risk of RPA. Restricting analyses to euthyroid individuals, additional multivariable models, and stratification did not change estimates. We found a SNP (rs943080) in the VEGF-A gene, associated with AMD, to be significant in the TSH GWAS (P = 1.2 x 10(-4)). Adding this SNP to multivariable models did not change estimates.

CONCLUSIONS

Higher FT4 values are associated with increased risk of AMD - even in euthyroid individuals - and increased risk of RPA. Our data suggest an important role of thyroid hormone in pathways leading to AMD.

Prevalence of refractive error in Europe: the European Eye Epidemiology (E(3)) Consortium

To estimate the prevalence of refractive error in adults across Europe. Refractive data (mean spherical equivalent) collected between 1990 and 2013 from fifteen population-based cohort and cross-sectional studies of the European Eye Epidemiology (E(3)) Consortium were combined in a random effects meta-analysis stratified by 5-year age intervals and gender. Participants were excluded if they were identified as having had cataract surgery, retinal detachment, refractive surgery or other factors that might influence refraction. Estimates of refractive error prevalence were obtained including the following classifications: myopia ≤-0.75 diopters (D), high myopia ≤-6D, hyperopia ≥1D and astigmatism ≥1D. Meta-analysis of refractive error was performed for 61,946 individuals from fifteen studies with median age ranging from 44 to 81 and minimal ethnic variation (98 % European ancestry). The age-standardised prevalences (using the 2010 European Standard Population, limited to those ≥25 and <90 years old) were: myopia 30.6 % [95 % confidence interval (CI) 30.4-30.9], high myopia 2.7 % (95 % CI 2.69-2.73), hyperopia 25.2 % (95 % CI 25.0-25.4) and astigmatism 23.9 % (95 % CI 23.7-24.1). Age-specific estimates revealed a high prevalence of myopia in younger participants [47.2 % (CI 41.8-52.5) in 25-29 years-olds]. Refractive error affects just over a half of European adults. The greatest burden of refractive error is due to myopia, with high prevalence rates in young adults. Using the 2010 European population estimates, we estimate there are 227.2 million people with myopia across Europe.

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.

ARHGEF12 influences the risk of glaucoma by increasing intraocular pressure

Primary open-angle glaucoma (POAG) is a blinding disease. Two important risk factors for this disease are a positive family history and elevated intraocular pressure (IOP), which is also highly heritable. Genes found to date associated with IOP and POAG are ABCA1, CAV1/CAV2, GAS7 and TMCO1. However, these genes explain only a small part of the heritability of IOP and POAG. We performed a genome-wide association study of IOP in the population-based Rotterdam Study I and Rotterdam Study II using single nucleotide polymorphisms (SNPs) imputed to 1000 Genomes. In this discovery cohort (n = 8105), we identified a new locus associated with IOP. The most significantly associated SNP was rs58073046 (β = 0.44, P-value = 1.87 × 10(-8), minor allele frequency = 0.12), within the gene ARHGEF12. Independent replication in five population-based studies (n = 7471) resulted in an effect size in the same direction that was significantly associated (β = 0.16, P-value = 0.04). The SNP was also significantly associated with POAG in two independent case-control studies [n = 1225 cases and n = 4117 controls; odds ratio (OR) = 1.53, P-value = 1.99 × 10(-8)], especially with high-tension glaucoma (OR = 1.66, P-value = 2.81 × 10(-9); for normal-tension glaucoma OR = 1.29, P-value = 4.23 × 10(-2)). ARHGEF12 plays an important role in the RhoA/RhoA kinase pathway, which has been implicated in IOP regulation. Furthermore, it binds to ABCA1 and links the ABCA1, CAV1/CAV2 and GAS7 pathway to Mendelian POAG genes (MYOC, OPTN, WDR36). In conclusion, this study identified a novel association between IOP and ARHGEF12.

Meta-analysis of Genome-Wide Association Studies Identifies Novel Loci Associated With Optic Disc Morphology

Primary open-angle glaucoma is the most common optic neuropathy and an important cause of irreversible blindness worldwide. The optic nerve head or optic disc is divided in two parts: a central cup (without nerve fibers) surrounded by the neuroretinal rim (containing axons of the retinal ganglion cells). The International Glaucoma Genetics Consortium conducted a meta-analysis of genome-wide association studies consisting of 17,248 individuals of European ancestry and 6,841 individuals of Asian ancestry. The outcomes of the genome-wide association studies were disc area and cup area. These specific measurements describe optic nerve morphology in another way than the vertical cup-disc ratio, which is a clinically used measurement, and may shed light on new glaucoma mechanisms. We identified 10 new loci associated with disc area (CDC42BPA, F5, DIRC3, RARB, ABI3BP, DCAF4L2, ELP4, TMTC2, NR2F2, and HORMAD2) and another 10 new loci associated with cup area (DHRS3, TRIB2, EFEMP1, FLNB, FAM101, DDHD1, ASB7, KPNB1, BCAS3, and TRIOBP). The new genes participate in a number of pathways and future work is likely to identify more functions related to the pathogenesis of glaucoma.

Population-based evaluation of retinal nerve fiber layer, retinal ganglion cell layer, and inner plexiform layer as a diagnostic tool for glaucoma

PURPOSE

We determined the glaucoma screening performance of regional optical coherence tomography (OCT) layer thickness measurements in the peripapillary and macular region, in a population-based setting.

METHODS

Subjects (n = 1224) in the Rotterdam Study underwent visual field testing (Humphrey Field Analyzer) and OCT of the macula and optic nerve head (Topcon 3-D OCT-1000). We determined the mean thicknesses of the retinal nerve fiber layer (RNFL), retinal ganglion cell layer (RGCL), and inner plexiform layer for regions-of-interest; thus, defining a series of OCT parameters, using the Iowa Reference Algorithms. Reference standard was the presence of glaucomatous visual field loss (GVFL); controls were subjects without GVFL, an intraocular pressure (IOP) of 21 mm Hg or less, and no positive family history for glaucoma. We calculated the area under the receiver operating characteristics curve (AUCs) and the sensitivity at 97.5% specificity for each parameter.

RESULTS

After excluding 23 subjects with an IOP > 21 mm Hg and 73 subjects with a positive family history for glaucoma, there were 1087 controls and 41 glaucoma cases. Mean RGCL thickness in the inferior half of the macular region showed the highest AUC (0.85; 95% confidence interval [CI] 0.77-0.92) and sensitivity (53.7%; 95% CI, 38.7-68.0%). The mean thickness of the peripapillary RNFL had an AUC of 0.77 (95% CI, 0.69-0.85) and a sensitivity of 24.4% (95% CI, 13.7-39.5%).

CONCLUSIONS

Macular RGCL loss is at least as common as peripapillary RNFL abnormalities in population-based glaucoma cases. Screening for glaucoma using OCT-derived regional thickness identifies approximately half of those cases of glaucoma as diagnosed by perimetry.

Harmonizing the classification of age-related macular degeneration in the three-continent AMD consortium

PURPOSE

To describe methods to harmonize the classification of age-related macular degeneration (AMD) phenotypes across four population-based cohort studies: the Beaver Dam Eye Study (BDES), the Blue Mountains Eye Study (BMES), the Los Angeles Latino Eye Study (LALES), and the Rotterdam Study (RS).

METHODS

AMD grading protocols, definitions of categories, and grading forms from each study were compared to determine whether there were systematic differences in AMD severity definitions and lesion categorization among the three grading centers. Each center graded the same set of 60 images using their respective systems to determine presence and severity of AMD lesions. A common 5-step AMD severity scale and definitions of lesion measurement cutpoints and early and late AMD were developed from this exercise.

RESULTS

Applying this severity scale changed the age-sex adjusted prevalence of early AMD from 18.7% to 20.3% in BDES, from 4.7% to 14.4% in BMES, from 14.1% to 15.8% in LALES, and from 7.5% to 17.1% in RS. Age-sex adjusted prevalences of late AMD remained unchanged. Comparison of each center's grades of the 60 images converted to the consortium scale showed that exact agreement of AMD severity among centers varied from 61.0-81.4%, and one-step agreement varied from 84.7-98.3%.

CONCLUSION

Harmonization of AMD classification reduced categorical differences in phenotypic definitions across the studies, resulted in a new 5-step AMD severity scale, and enhanced similarity of AMD prevalence among the four cohorts. Despite harmonization it may still be difficult to remove systematic differences in grading, if present.

Meta-analysis of genome-wide association studies identifies novel loci that influence cupping and the glaucomatous process

Glaucoma is characterized by irreversible optic nerve degeneration and is the most frequent cause of irreversible blindness worldwide. Here, the International Glaucoma Genetics Consortium conducts a meta-analysis of genome-wide association studies of vertical cup-disc ratio (VCDR), an important disease-related optic nerve parameter. In 21,094 individuals of European ancestry and 6,784 individuals of Asian ancestry, we identify 10 new loci associated with variation in VCDR. In a separate risk-score analysis of five case-control studies, Caucasians in the highest quintile have a 2.5-fold increased risk of primary open-angle glaucoma as compared with those in the lowest quintile. This study has more than doubled the known loci associated with optic disc cupping and will allow greater understanding of mechanisms involved in this common blinding condition.

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.

Lipids, lipid genes, and incident age-related macular degeneration: the three continent age-related macular degeneration consortium

PURPOSE

To describe associations of serum lipid levels and lipid pathway genes to the incidence of age-related macular degeneration (AMD).

DESIGN

Meta-analysis.

METHODS

setting: Three population-based cohorts. population: A total of 6950 participants from the Beaver Dam Eye Study (BDES), Blue Mountains Eye Study (BMES), and Rotterdam Study (RS). observation procedures: Participants were followed over 20 years and examined at 5-year intervals. Hazard ratios associated with lipid levels per standard deviation above the mean or associated with each additional risk allele for each lipid pathway gene were calculated using random-effects inverse-weighted meta-analysis models, adjusting for known AMD risk factors. main outcome measures: Incidence of AMD.

RESULTS

The average 5-year incidences of early AMD were 8.1%, 15.1%, and 13.0% in the BDES, BMES, and RS, respectively. Substantial heterogeneity in the effect of cholesterol and lipid pathway genes on the incidence and progression of AMD was evident when the data from the 3 studies were combined in meta-analysis. After correction for multiple comparisons, we did not find a statistically significant association between any of the cholesterol measures, statin use, or serum lipid genes and any of the AMD outcomes in the meta-analysis.

CONCLUSION

In a meta-analysis, there were no associations of cholesterol measures, history of statin use, or lipid pathway genes to the incidence and progression of AMD. These findings add to inconsistencies in earlier reports from our studies and others showing weak associations, no associations, or inverse associations of high-density lipoprotein cholesterol and total cholesterol with AMD.

Retinal vascular caliber and metabolic syndrome in a Chinese population

BACKGROUND

Microvascular changes have been associated with the metabolic syndrome.

METHODS

We included 869 participants aged ≥ 40 years from the High-risk for Diabetes Changfeng Study, who had gradable fundus photographs. On digital photographs sum retinal arteriolar and venular calibers were measured with a semi-automated system. Metabolic syndrome was defined according to the International Diabetes Federation consensus.

RESULTS

A total of 286 (32.9%) participants was diagnosed with metabolic syndrome. Participants with narrower retinal arteriolar caliber were more often diagnosed with metabolic syndrome (odds ratio 1.78, 95% confidence interval 1.02 – 3.10; lowest vs highest quintile). Additionally adjusting for age, gender, education, smoking and weekly activity, and adding arteriolar and venular caliber simultaneously in the same models did not alter these associations. In the component analyses, participants with narrower retinal arteriolar caliber were more likely to have central obesity, dyslipidaemia or raised blood pressure, and less likely to have raised fasting plasma glucose. The association between wider venular caliber and metabolic syndrome was less pronounced and non-significant (odds ratio 1.34; 95% confidence interval 0.79 – 2.38; highest vs lowest quintile).

CONCLUSION

Retinal arteriolar narrowing and, to a lesser extent, retinal venular dilatation were associated with metabolic syndrome in this Chinese population. These vascular changes, although small in magnitude, may still be important in the pathophysiological mechanisms involved in the metabolic syndrome.