Ocular Components Research Articles

Repeatability and reproducibility of ocular biometry using a new noncontact optical low-coherence interferometer

To assess the precision of ocular biometry with a new noncontact optical low-coherence interferometer (Aladdin) in healthy subjects and patients with cataracts. Eye Hospital of Wenzhou Medical University, Wenzhou, China. Observational cross-sectional study. Eyes from healthy subjects and eyes from patients with cataracts were examined with the new interferometer. Axial length (AL), anterior chamber depth (ACD), keratometry (K), and white-to-white (WTW) values were measured by 2 operators. The test-retest repeatability, coefficient of variation (CoV), and intraclass correlation coefficient (ICC) were calculated to evaluate intraoperator repeatability. Different-operator comparison was analyzed with paired t tests and Bland-Altman plots to assess interoperator reproducibility. Ninety-eight people were enrolled for this study, of which 52 eyes were from healthy subjects and 46 eyes were from patients with cataracts. The AL was the most repeatable and reproducible parameter. The ACD, K values, and WTW measurements were highly repeatable in healthy subjects with CoV less than 0.89% and ICC more than 0.94. However, in patients with cataracts, high repeatability could only be observed for AL, ACD, and K values, whereas WTW measurement had test-retest repeatability of 0.80 mm and an ICC of 0.795. Bland-Altman analysis also showed good agreement between the 2 operators for ocular component measurements, except that the WTW in patients with cataracts had wider 95% limits of agreement (range -0.88 to 0.95 mm). The new biometer showed excellent intraoperator repeatability and interoperator reproducibility for AL, ACD, and K values measurements in both groups. The precision of WTW measurements was lower in patients with cataracts. No author has a financial or proprietary interest in any material or method mentioned.

Blue Light Protects Against Temporal Frequency Sensitive Refractive Changes.

Time spent outdoors is protective against myopia. The outdoors allows exposure to short-wavelength (blue light) rich sunlight, while indoor illuminants can be deficient at short-wavelengths. In the current experiment, we investigate the role of blue light, and temporal sensitivity, in the emmetropization response. Five-day-old chicks were exposed to sinusoidal luminance modulation of white light (with blue; N = 82) or yellow light (without blue; N = 83) at 80% contrast, at one of six temporal frequencies: 0, 0.2, 1, 2, 5, 10 Hz daily for 3 days. Mean illumination was 680 lux. Changes in ocular components and corneal curvature were measured. Refraction, eye length, and choroidal changes were dependent on the presence of blue light (P < 0.03, all) and on temporal frequency (P < 0.03, all). In the presence of blue light, refraction did not change across frequencies (mean change -0.24 [diopters] D), while in the absence of blue light, we observed a hyperopic shift (>1 D) at high frequencies, and a myopic shift (>-0.6 D) at low frequencies. With blue light there was little difference in eye growth across frequencies (77 μm), while in the absence of blue light, eyes grew more at low temporal frequencies and less at high temporal frequencies (10 vs. 0.2 Hz: 145 μm; P < 0.003). Overall, neonatal astigmatism was reduced with blue light. Illuminants rich in blue light can protect against myopic eye growth when the eye is exposed to slow changes in luminance contrast as might occur with near work.

Longitudinal Changes in Lens Thickness in Myopic Children Enrolled in the Correction of Myopia Evaluation Trial (COMET)

ABSTRACTPurpose: To describe longitudinal changes in lens thickness in myopic children in the Correction of Myopia Evaluation Trial (COMET) and to investigate the association between these changes and myopia progression.Methods: Four-hundred sixty-nine 6 to <12-year-old children with −1.25 to −4.50 D of myopia were enrolled in COMET, a clinical trial comparing single vision lenses (SVLs) versus progressive addition lenses (PALs) for slowing myopia. Children remained in their original lenses for 5 years and then could wear contact lenses, SVLs or PALs. Myopia by cycloplegic autorefraction (Nidek ARK 700A) and ocular components, including lens thickness, by A-scan ultrasound (Sonomed A2500) were measured annually over 11 years. Analyses of lens thickness were based on right eye data from 426 children with refractions fit with Gompertz functions. Longitudinal lens thickness measurements for each participant were fit with a third-degree polynomial function, and average polynomial functions were calculated for three groups of children previously identified based on Gompertz functions: 6–7 years at baseline (n = 40), ≥8 years with progressing myopia (n = 329), and ≥8 years with non-progressing myopia (n = 56). ANOVAs were used for comparing the lens curve-based parameters among the three groups. Associations between lens and Gompertz parameters were assessed using Pearson correlations.Results: Overall, between 6 and 18 years the lenses thinned and then thickened, with the minimum value of 3.37 ± 0.15mm reached at 11.56 ± 2.04 years. The minimum lens thickness did not differ among the three myopia groups (p = 0.09), nor was it correlated with the amount of myopia at lens minimum or amount of final myopia (r’s = −0.01 and −0.03, respectively, p’s > 0.05).Conclusion: As a similar pattern of change in lens thickness with age was found in all children, whether their myopia progressed or not, these results suggest that the association of lens thinning and thickening with the course of myopia is coincidental rather than causal.

Crystalline lens and refractive development.

Individual refractive errors usually change along lifespan. Most children are hyperopic in early life. This hyperopia is usually lost during growth years, leading to emmetropia in adults, but myopia also develops in children during school years or during early adult life. Those subjects who remain emmetropic are prone to have hyperopic shifts in middle life. And even later, at older ages, myopic shifts are developed with nuclear cataract. The eye grows from 15 mm in premature newborns to approximately 24 mm in early adult years, but, in most cases, refractions are maintained stable in a clustered distribution. This growth in axial length would represent a refractive change of more than 40 diopters, which is compensated by changes in corneal and lens powers. The process which maintains the balance between the ocular components of refraction during growth is still under study. As the lens power cannot be measured in vivo, but can only be calculated based on the other ocular components, there have not been many studies of lens power in humans. Yet, recent studies have confirmed that the lens loses power during growth in children, and that hyperopic and myopic shifts in adulthood may be also produced by changes in the lens. These studies in children and adults give a picture of the changing power of the lens along lifespan. Other recent studies about the growth of the lens and the complexity of its internal structure give clues about how these changes in lens power are produced along life.

TSH-receptor-expressing fibrocytes and thyroid-associated ophthalmopathy.

Thyroid-associated ophthalmopathy (TAO) is a vexing and undertreated ocular component of Graves disease in which orbital tissues undergo extensive remodelling. My colleagues and I have introduced the concept that fibrocytes expressing the haematopoietic cell antigen CD34 (CD34(+) fibrocytes), which are precursor cells of bone-marrow-derived monocyte lineage, express the TSH receptor (TSHR). These cells also produce several other proteins whose expression was traditionally thought to be restricted to the thyroid gland. TSHR-expressing fibrocytes in which the receptor is activated by its ligand generate extremely high levels of several inflammatory cytokines. Acting in concert with TSHR, the insulin-like growth factor 1 receptor (IGF-1R) expressed by orbital fibroblasts and fibrocytes seems to be necessary for TSHR-dependent cytokine production, as anti-IGF-1R blocking antibodies attenuate these proinflammatory actions of TSH. Furthermore, circulating fibrocytes are highly abundant in patients with TAO and seem to infiltrate orbital connective tissues, where they might transition to CD34(+) fibroblasts. My research group has postulated that the infiltration of fibrocytes into the orbit, their unique biosynthetic repertoire and their proinflammatory and profibrotic phenotype account for the characteristic properties exhibited by orbital connective tissues that underlie susceptibility to TAO. These insights, which have emerged in the past few years, might be of use in therapeutically targeting pathogenic orbit-infiltrating fibrocytes selectively by utilizing novel biologic agents that interfere with TSHR and IGF-1R signalling.

Assessment of Full-Eye Response to Osmotic Stress in Mouse Model In Vivo Using Optical Coherence Tomography.

NaCl based solutions were applied as osmotic stress agents to alter the hydration state of the mouse eye. Full-eye responses to these osmotic challenges were monitored in vivo using a custom-built optical coherence tomography (OCT) with an extended imaging range of 12.38 mm. Dynamic changes in the mouse eye were quantified based on the OCT images using several parameters, including the central corneal thickness (CCT), the anterior chamber depth (ACD), the crystalline lens thickness (LT), the cornea-retina distance (CRD), the iris curvature (IC), and the lens scattering intensity (LSI). Apparent but reversible changes in the morphology of almost all the ocular components and the light transparency of the lens are exhibited. Particularly, the ocular dehydration induced by the hypertonic challenges resulted in a closing of the iridocorneal angle and an opacification of the lens. Our results indicated that the ocular hydration is an important physiological process which might be correlated with various ocular disorders, such as dry eye, cataract, and angle-closure glaucoma, and would affect the biometry and imaging of the eye. OCT uniquely enables the comprehensive study of the dynamic full-eye responses to the ocular hydration in vivo.

Past History of Ocular Trauma in an Iranian Population-Based Study: Prevalence and its Associated Factors.

Purpose:The purpose of this study was to determine the prevalence of a history of ocular trauma and its association to age, sex, and biometric components.Materials and Methods:Residents of Shahroud, Iran aged 40–64 years, were sampled through a cross-sectional study using multistage cluster sampling. Three hundred clusters were randomly selected, and 20 individuals were systematically selected from each cluster. The subjects underwent optometric and ophthalmic examinations, and ocular imaging. A history of ocular trauma was determined through personal interviews.Results:The prevalence of a history of trauma and blunt trauma, sharp trauma, and chemical burns were 8.57%, 3.91%, 3.82%, and 1.93%, respectively. After adjusting for age, the rate of all types of trauma was significantly higher for males. Only the prevalence of chemical burns significantly decreased with aging. A history of hospitalization was stated by 1.64% of the subjects. The axial length was significantly longer in cases with a history of trauma. The corneal curvature was significantly larger in cases with a history of sharp trauma and chemical burns. The prevalence of corneal opacities was significantly higher among cases with a history of the blunt trauma odds ratio (OR = 2.33) and sharp trauma (OR = 4.46). Based on corrected visual acuity, the odds of blindness was 3.32 times higher in those with a history of ocular trauma (P < 0.001).Conclusion:A considerable proportion of the 40–64-year-old population reported a history of ocular trauma. This observation has important health implications. Blindness, corneal opacities, and posterior subcapsular cataract were observed more frequently among these cases, and they demonstrated differences in some ocular biometric components.

The Genetics and the Genomics of Primary Congenital Glaucoma.

The sight is one of the five senses allowing an autonomous and high-quality life, so that alterations of any ocular component may result in several clinical phenotypes (from conjunctivitis to severe vision loss and irreversible blindness). Most parts of clinical phenotypes have been significantly associated with mutations in genes regulating the normal formation and maturation of the anterior segments of the eye. Among the eye anterior segment disorders, special attention is given to Glaucoma as it represents one of the major causes of bilateral blindness in the world, with an onset due to Mendelian or multifactorial genetic-causative traits. This review will point out the attention on the Primary Congenital Glaucoma (PCG), which is usually transmitted according to an autosomal-recessive inheritance pattern. Taking into consideration the genetic component of the PCG, it is possible to observe a strong heterogeneity concerning the disease-associated loci (GLC3), penetrance defects, and expressivity of the disease. Given the strong PGC heterogeneity, pre- and posttest genetic counseling plays an essential role in the achievement of an appropriate management of PCG, in terms of medical, social, and psychological impact of the disease.

Normal Ocular Ultrasonographic Biometry and Fundus Imaging of Indian Camel (Camelus dromedarius)

The present study was aimed to document the normal measurements of different ocular components of eight adult live Indian camels (Camelus dromedarius) of either sex using B-mode ultrasonography and normal ocular fundus using fundus imaging camera. In all animals, corneal anesthesia was achieved by instilling Proparacaine HCl 0.5% directly on the cornea. Ultrasonographic scanning of eyes was done in sternal recumbency with linear transducer (12–18 MHz) by transcorneal approach. Anterior chamber depth was 0.48+0.006 cm, while vitreous depth was 1.74+0.02 cm. Anterio-posterior depth of lens and Latero-medial diameter of lens were 1.05+0.008 cm and 1.92+0.01 cm, respectively. Globe axial length was 3.29+0.03 cm. Camel eye was aspherical and no significant difference was observed in all the parameters of right and left eyes. Before funduscopy, the pupils were dilated with a short-acting mydriatic such as 1% tropicamide prior to examination. In camels, fundus examination was somewhat cumbersome. The vascular pattern was holangiotic and was similar to other ruminants. Unlike bovines, tapetal non-tapetal differentiation was not clear and sometimes in a single fundus with islands of pigmented and non-pigmented areas could be observed. They usually have a prominent Bergmeister's papilla, which is the posterior remnant of the hyaloid artery.

Human eye development is characterized by coordinated expression of fibrillin isoforms.

Mutations in human fibrillin-1 and -2, which are major constituents of tissue microfibrils, can affect multiple ocular components, including the ciliary zonule, lens, drainage apparatus, cornea, and retina. However, the expression pattern of the three human fibrillins and an integral microfibrillar component, MAGP1, during human eye development is not known. We analyzed sections from human eyes at gestational weeks (GWs) 6, 8, and 11 and at 1 and 3 years of age with antibodies specific for each human fibrillin isoform or MAGP1, using immunofluorescence microscopy. During embryonic development, each fibrillin isoform was detected in vascular structures bridging the ciliary body and the developing lens, hyaloid vasculature, and retina. In addition, they were present in the developing corneal basement membranes and lens capsule. MAGP1 codistributed with the fibrillin isoforms. In contrast, the juvenile zonule was composed of fibrillin-1 microfibrils containing MAGP1, but fibrillin-2 was absent and fibrillin-3 was only sparsely detected. Fibrillin-1, -2, and, unique to humans, fibrillin-3 are found in various ocular structures during human embryonic eye development, whereas fibrillin-1 dominates the postnatal zonule. We speculate that vasculature spanning the ciliary body and lens, which elaborates fibrillin-2 and -3, may provide an initial scaffold for fibrillin assembly and zonule formation.

Change of ocular components after cycloplegia in children using the IOLMaster

AbstractPurpose Ocular components are traditionally measured using A‐scan ultrasound. With ultrasound, the probe makes contact with the cornea, so there is some problem in children. The IOLMaster is non‐contact device that can measure ocular components, so it can be used in children with poor cooperation. We evaluated change of ocular components after cycloplegia in children using the IOLMaster.Methods One hundred and sixty eight children aged from 3 to 15 years were recruited from the Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine. Children with ocular problem except refractive error were excluded. Pre‐ and post‐cycloplegic corneal curvature (CC), anterior chamber depth (ACD) and axial length (AL) on the right eye were measured with the IOLMaster. We evaluated the change of ocular components after cycloplegia by age and refractive error.Results ACD was 0.134 ± 0.134mm deeper after cycloplegia (p=.000). The amount of change had statistically significant negative correlation with age (Pearson correlation ‐0.332, p=.006), but it was not significantly different between myopic and hyperopic group after age correction (p=.398). AL was also significantly elongated after cycloplegia (p=.000), but the amount of change was very small (0.011 ± 0.022mm). There was no change in CC after cycloplegia (p=.428).Conclusion Effect of cycloplegia on ACD in children measured with the IOLMaster was significant. We suppose that the negative correlation between the change of ACD and age may be associated with decreasing accommodation with age.

Association between ocular optical components and refractive errors in bank’s Employees of Sari, Iran

AbstractPurpose To investigate the association between ocular optical components and refractive errors in bank’s employees of Sari, IranMethods In this cross sectional study 398 bank’s employees of Sari, Iran were selected, 232 of them used the eyes for close work (computers, etc…) for a minimum of 7 hours per day for the 5 past years. The other 166 bank’s employees acted as a control group and did not did a close work more than one hour daily for the 5 past years. Age of the participants were between 25 to 40 years old. Axial length, anterior chamber depth, lens diameter and vitreous depth were measured with Nidek biometer. Corneal radius and non cycloplegic refraction performed with autorefracto‐keratometer; refractive errors were checked by retinoscopy and subjective tests. There was a high correlation between equivalent sphere (ES) right and left eyes of the subjects (0.9) and data of the right eye was analyzed. Data were analyzed by using version 19 of SPSS software.Results The results showed that the bank’s employees who had excessive use of the eyes for near work have more axial length (p&lt;0.001), more anterior chamber depth (p=0.003) and more vitreous chamber depth (p&lt;0.001) than the control group. There was no significant difference between lens diameter (p=0.525) and cornel radius (p=0.666) of the two groups. There was correlation between axial length and SE by increasing in axial length (p&lt;0.000). The least amount correlation was found between lens diameter and ES (P&lt; 0.000).Conclusion The results of this study indicated that ocular optical components changed toward myopia in people who had excessive close work.

Optical quality of the diabetic eye: a review.

Diabetes mellitus is a metabolic disorder characterized by the presence of chronic hyperglycaemia. Several structural, morphological, and physiological changes in each of ocular component have been described in detail during the past decades. Due to these abnormalities, the diabetic patient undergoes a degradation of the retinal image by an increase of higher ocular aberrations and ocular scattering coming from mainly tear film, cornea, and crystalline lens. This review aims to provide an overview of current knowledge about the effects of diabetes mellitus in these optical phenomena and its consequence on the visual quality of the diabetic patient.

Activation of dopamine D2 receptor is critical for the development of form-deprivation myopia in the C57BL/6 mouse.

This study used dopamine D2 receptor (D2R) knockout (KO) mice to investigate the role of D2R activity in the development of form-deprivation myopia (FDM). Sulpiride, a D2R antagonist, was administered systemically into wild-type (WT) mice to validate the involvement of D2R in FDM development. The D2R KO and WT C57BL/6 mice were subjected to FDM. Wild-type mice received daily intraperitoneal injections of sulpiride, 8 μg/g body weight, for a period of 4 weeks. The body weight, refraction, corneal radius of curvature, and ocular axial components were measured at week 4 of the experiment. Differences in all ocular parameters between the experimental and control groups were compared statistically. Form-deprivation myopia in D2R KO mice (FD-KO) was significantly reduced compared with their WT littermates (interocular difference, -2.12 ± 0.91 diopter [D] in FD-KO versus -5.35 ± 0.83 D in FD-WT, P = 0.014), with a smaller vitreous chamber depth (0.008 ± 0.006 vs. 0.026 ± 0.006 mm, P = 0.044) and axial length (-0.001 ± 0.007 vs. 0.027 ± 0.008 mm, P = 0.007). Furthermore, FDM was attenuated in animals treated with sulpiride (-2.01 ± 0.31 D in FD-sulpiride versus -4.06 ± 0.30 D in FD-DMSO, P < 0.001) compared with those treated with vehicle, with a retardation in growth of vitreous chamber depth (-0.001 ± 0.006 vs. 0.022 ± 0.004 mm, P = 0.003) and axial length (-0.004 ± 0.007 vs. 0.027 ± 0.005 mm, P = 0.001). Genetic and pharmacological inactivation of D2R attenuates FDM development in mice, suggesting that dopamine acting on D2R appears to promote the development of FDM in C57BL/6 mice. Further studies are required to confirm these results using animal models in which retinal D2R is selectively blocked.

Kmeans-ICA based automatic method for ocular artifacts removal in a motorimagery classification.

Electroencephalogram (EEG) recordings aroused as inputs of a motor imagery based BCI system. Eye blinks contaminate the spectral frequency of the EEG signals. Independent Component Analysis (ICA) has been already proved for removing these artifacts whose frequency band overlap with the EEG of interest. However, already ICA developed methods, use a reference lead such as the ElectroOculoGram (EOG) to identify the ocular artifact components. In this study, artifactual components were identified using an adaptive thresholding by means of Kmeans clustering. The denoised EEG signals have been fed into a feature extraction algorithm extracting the band power, the coherence and the phase locking value and inserted into a linear discriminant analysis classifier for a motor imagery classification.

Ocular components during the ages of ocular development.

To determine the distribution of ocular biometric components and their correlation with age and sex during the ages of ocular development in a 6- to 18-year-old population in Iran. In this cross-sectional study, which was performed in October 2012, multi-stage stratified cluster sampling was used to sample the study population from Dezful schools, a city in the southwest of Iran. Biometric examinations were done by an experienced optometrist using the LENSTAR/BioGraph (WaveLight AG, Erlangen, Germany). Among 864 selected students, 683 participated in the study (response rate: 79.1%); 377 participants (55.2%) were male, and the mean age of the participants was 12 ± 3.4 years (range: 6-18 years). The mean and 95% confidence interval of axial length (AL) were 23.13 mm (22.93-23.33), anterior chamber depth (ACD) was 3.01 mm (2.96-3.06), lens thickness (LT) was 3.58 mm (3.55-3.61), central corneal thickness (CCT) was 549.33 mic (546.59-552.07), corneal radius (CR) was 7.77 mm (7.74-7.81), corneal diameter (CD) was 12.34 mm (12.31-12.38) and pupil diameter (PD) was 4.97 (4.91-5.03). Mean AL, ACD, CD and CR were significantly higher in boys, and mean LT was significantly higher in girls. AL and ACD increased, while LT decreased significantly with age. Myopia was associated with an increase in AL and ACD, and hyperopia was associated with an increase in LT and a decrease in ACD. This study evaluated the distribution of the biometric components of the eye during the ages of ocular development in an Iranian population. In this age range, the majority of the changes were observed in the AL and LT.

Ocular alignment and refraction in preterm children at 1 and 6 years old.

PurposeTo investigate cycloplegic refraction and ocular alignment in a population of preterm children at 1 and 6 years old.Patients and methodsWe included 261 preterm infants with a birth weight ≤1,500 g and a gestational age ≤32 weeks; there were 217 preterm infants (group 1), 28 preterm infants with mild retinopathy of prematurity (ROP) (group 2), and 16 preterm infants affected by severe ROP (group 3). Each patient underwent retinoscopy, ocular alignment assessment, and fundus examination at 1 and 6 years old.ResultsThe prevalence of refractive errors and ocular alignment abnormalities at 1 year old in groups 2 and 3 compared to group 1 were, respectively (P<0.05): myopia 18% and 40.6% versus 6.9%; hyperopia 28.6% and 22% versus 39.2%; astigmatism 53.4% and 37.4% versus 53.9%; and strabismus 12.5% and 38% versus 5.3%. At 6 years old, they were, respectively (P<0.05): myopia 10.8% and 28.4% versus 7.4%; hyperopia 48.3% and 40.5% versus 62%; astigmatism 40.9% and 31.1% versus 30.6%; and strabismus 25% and 56.25% versus 11.5%.ConclusionAt 6 years old, we observed increased rates of both hyperopia and strabismus in all groups compared to 1-year-old children. In preterm children with mild and severe ROP, we recorded increased rates of myopia and strabismus versus preterm children without ROP, and the risk of developing these disorders increased significantly with ROP severity. Astigmatism at 1 year old is not predictive of further development during growth. Patients born prematurely should be informed of the possible risks of ocular alterations due to refractive and ocular component changes.

Evaluation of a new optical biometry device for measurements of ocular components and its comparison with IOLMaster

ObjectiveTo assess the reliability of ocular component measurements with a new optical biometry device (AL-Scan; Nidek) and compare these measurements with those of the IOLMaster (Carl Zeiss Meditec) in patients...

A fully automatic ocular artifact removal from EEG based on fourth-order tensor method

The aim of this paper is to propose a fully automatic system using the underdetermined blind source separation (UBSS) method and kurtosis to remove ocular artifacts (OAs) from scalp electroencephalogram (EEG). The fully automatic system about OAs rejection is devised with the fourth-order tensor method (FOOBI). Firstly, the FOOBI method decomposes multiple EEG channels into a relative large number of source components. The kurtosis value is used to identify the ocular components in these source components. Then, the free-ocular sources components are reconstructed to EEG without OAs. The simulations show that the FOOBI method can completely separate the ocular signals from the observed signals. The data that have got rid of the OAs are used to classify with the epileptic EEG. The classification accuracy acquired by FOOBI method is better than the independent component analysis (ICA). The results inferred that the FOOBI method can not only completely remove the OAs from the observed signals but also preserve an amount of useful information of EEG. Compared with the ICA method, this fully automatic system is more suitable to remove OAs.

Lens Power in a Population-Based Cross-Sectional Sample of Adults Aged 40 to 64 Years in the Shahroud Eye Study

To report on calculated lens power in adults in relation to other ocular components of refraction, analyzed in relation to secular change in height and education. The first phase of the Shahroud Eye Cohort Study is a cross-sectional population-based study in Iranian subjects 40 to 64 years old. Data on cycloplegic spherical equivalent refraction and the ocular components of the right eyes were used for the calculation of crystalline lens power with Bennett's formula. Interactions between sex and age as independent variables were analyzed by two-way analysis of variances. Cycloplegic refraction data and biometry were obtained from 4592 subjects, of whom 2666 (58%) were women. The mean lens power showed a biphasic trend. Up to the age of 50, younger subjects had lower lens power than older subjects, but after the age of 50, older subjects had lower lens power. A secular trend in height was found, with younger subjects significantly taller than older ones. Taller men or women had longer eyes, with flatter corneas and less powerful lenses, independent of refractive error. In multiple regression models, corneal power (P < 0.001), axial length (P < 0.001), and lens power (P < 0.001) were all associated with height, independent of age and sex. There was an unexpected biphasic pattern of the distribution of lens power with age in this cross-sectional study. Younger subjects were taller, and despite having longer axial lengths, their bigger eyes were still predominantly emmetropic. The greater axial lengths were counterbalanced by both lower corneal and lower lens powers.