A Pixel-Based Machine-Learning Model For Three-Dimensional Reconstruction of Vitreous Anatomy.

Purpose: To develop a machine-learning image processing model for three-dimensional (3D) reconstruction of vitreous anatomy visualized with swept-source optical coherence tomography (SS-OCT). Methods: Healthy subjects were imaged with SS-OCT. Scans of sufficient quality were transferred into the Fiji is just ImageJ image processing toolkit, and proportions of the resulting stacks were adjusted to form cubic voxels. Image-averaging and Trainable Weka Segmentation using Sobel and variance edge detection and directional membrane projections filters were used to enhance and interpret the signals from vitreous gel, liquid spaces within the vitreous, and interfaces between the former. Two classes were defined: "Septa" and "Other." Pixels were selected and added to each class to train the classifier. Results were generated as a probability map. Thresholding was performed to remove pixels that were classified with low confidence. Volume rendering was performed with TomViz. Results: Forty-seven eyes of 34 healthy subjects were imaged with SS-OCT. Thirty-four cube scans from 25 subjects were of sufficient quality for volume rendering. Clinically relevant vitreous features including the premacular bursa, area of Martegiani, and prevascular vitreous fissures and cisterns, as well as varying degrees of vitreous degeneration were visualized in 3D. Conclusions: A machine-learning model for 3D vitreous reconstruction of SS-OCT cube scans was developed. The resultant high-resolution 3D movies illustrated vitreous anatomy in a manner like triamcinolone-assisted vitrectomy or postmortem dye injection. Translational Relevance: This machine learning model now allows for comprehensive examination of the vitreous structure beyond the vitreoretinal interface in 3D with potential applications for common disease states such as the vitreomacular traction and Macular Hole spectrum of diseases or proliferative diabetic retinopathy.

Multi-view convolutional neural networks for automated ocular structure and tumor segmentation in retinoblastoma.

In retinoblastoma, accurate segmentation of ocular structure and tumor tissue is important when working towards personalized treatment. This retrospective study serves to evaluate the performance of multi-view convolutional neural networks (MV-CNNs) for automated eye and tumor segmentation on MRI in retinoblastoma patients. Forty retinoblastoma and 20 healthy-eyes from 30 patients were included in a train/test (N = 29 retinoblastoma-, 17 healthy-eyes) and independent validation (N = 11 retinoblastoma-, 3 healthy-eyes) set. Imaging was done using 3.0 T Fast Imaging Employing Steady-state Acquisition (FIESTA), T2-weighted and contrast-enhanced T1-weighted sequences. Sclera, vitreous humour, lens, retinal detachment and tumor were manually delineated on FIESTA images to serve as a reference standard. Volumetric and spatial performance were assessed by calculating intra-class correlation (ICC) and dice similarity coefficient (DSC). Additionally, the effects of multi-scale, sequences and data augmentation were explored. Optimal performance was obtained by using a three-level pyramid MV-CNN with FIESTA, T2 and T1c sequences and data augmentation. Eye and tumor volumetric ICC were 0.997 and 0.996, respectively. Median [Interquartile range] DSC for eye, sclera, vitreous, lens, retinal detachment and tumor were 0.965 [0.950-0.975], 0.847 [0.782-0.893], 0.975 [0.930-0.986], 0.909 [0.847-0.951], 0.828 [0.458-0.962] and 0.914 [0.852-0.958], respectively. MV-CNN can be used to obtain accurate ocular structure and tumor segmentations in retinoblastoma.

Comparison of A-Scan ultrasonography and the Lenstar optical biometer in Guinea pig eyes.

OBJECTIVE: To compare the biometric parameters provided by A-scan ultrasonography and the Lenstar optical biometer in guinea pig eyes, including anterior segment depth (ASD), lens thickness (LT), vitreous chamber depth (VCD), and axial length (AL), and differences of them between treated form deprivation (FD) eyes and untreated fellow eyes after 4 weeks of FD. METHODS: Three-week-old guinea pigs (N = 41) were subjected to biometric measurements before monocular FD (baseline) and after a 4-week FD. Statistical analyses including within-subject standard deviation (SDwithin), coefficient of variation (CV), and intraclass correlation coefficient (ICC), used to evaluate repeatability for both the A-scan ultrasonography and the Lenstar individually, and correlation and Bland-Altman analyses were used to assess agreement between the two methods. The absolute values of ASD, LT, VCD and AL as measured by the two devices were compared, and the differences of them between treated (T) and untreated fellow (F) eyes (ΔASD, ΔLT, ΔVCD and ΔAL) (Δ = T-F) were compared between the two devices after 4 weeks of FD. RESULTS: Measurements by the Lenstar (ICC: 0.923-0.994) were more repeatable than A-scan ultrasonography (ICC: 0.825-0.870). There was a high correlation for AL (r = 0.851, P < 0.001), a moderate correlation for VCD (r = 0.571, P < 0.001) and LT (r = 0.423, P < 0.001), and a low correlation for ASD (r = 0.230, P < 0.01) between the two devices. The values for ASD, VCD and AL measured by A-scan ultrasonography were larger than those measured by the Lenstar (all, P < 0.001), while LT provided by A-scan ultrasonography was much smaller than that of the Lenstar (P < 0.001). Bland-Altman plots showed poor agreement of absolute values of the four parameters between the two devices. Moreover, there was a high correlation between both methods for ΔAL (r = 0.704, P < 0.001), a moderate correlation for ΔVCD (r = 0.534, P < 0.001) and ΔASD (r = 0.574, P < 0.001), and no correlation for ΔLT (r = 0.303, P = 0.054). The ΔASD, ΔLT, and ΔAL measurements obtained by A-scan ultrasonography were greater than those obtained by the Lenstar (all, P < 0.001), while ΔVCD was mildly smaller using A-scan ultrasonography (P < 0.05). Bland-Altman plots illustrated there is good agreement of ΔAL, ΔVCD, ΔASD, and ΔLT between the two devices. CONCLUSIONS: The Lenstar exhibited better repeatability and provided smaller measurements for AL, VCD and ASD than A-scan ultrasonography. Furthermore, a high correlation and a good agreement for the ΔAL was observed between the two devices after a period of FD. In summary, the two devices cannot replace each other directly to obtain absolute values of ASD, LT, VCD and AL, but the Lenstar still can serve as an option in measuring ΔAL between eyes in guinea pig myopia model.

Expression of Lymphatic Markers in the Berger's Space and Bursa Premacularis.

We previously reported that the bursa premacularis (BPM), a peculiar vitreous structure located above the macula, contains numerous cells expressing markers of lymphatic endothelial cells, such as podoplanin and LYVE-1. Herein, we examined the expression of lymphatic markers in the Berger's space (BS), BPM, and vitreous core (VC). BS, BPM, and VC specimens were selectively collected in macular hole and epiretinal membrane patients during vitrectomy and were then immunostained with antibodies for podoplanin, LYVE-1, and fibrillin-1 and -2. By visualization using triamcinolone acetonide, the BS was recognized as a sac-like structure with a septum located behind the lens as well as BPM. Those tissues adhered to the lens or retina in a circular manner by means of a ligament-like structure. Immunostaining showed intense expression of podoplanin and LYVE-1 in the BS. Both BS and BPM stained strongly positive for fibrillin-1 and -2. The VC was faintly stained with antibodies for those lymph-node markers. Our findings indicate that both BS and BPM possibly belong to the lymphatic system, such as lymph nodes, draining excess fluid and waste products into lymphatic vessels in the dura mater of the optic nerve and the ciliary body, respectively, via intravitreal canals.

Jules Germain Cloquet: del epónimo al anatomista del Romanticismo / Jules Germain Cloquet: From the eponymous to the anatomist of Romanticism

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Intraocular pressure and axial length changes during altitude acclimatization from Beijing to Lhasa.

PURPOSE: To investigate changes in intraocular pressure (IOP) and axial length (AL) on the ascent to high altitude from Beijing to Lhasa. PATIENTS AND METHODS: Twenty volunteers (17 men, 3 women) who had been sent to work in Lhasa, Tibet for more than 6 months were enrolled. One of their journeys from Beijing to Lhasa was chosen as the time for the examination. IOP, AL, corneal curvature (K), and blood pressure (BP) were measured in Beijing (altitude 43 m) and Lhasa (altitude 3658 m). Their first examination was conducted at least 1 day before arriving in Lhasa and the second examination after they had stayed in Lhasa for 7 days. The data from the highland and lowland examinations were analyzed with a paired-sample T test and Pearson's correlation coefficient was calculated for the association between IOP and average BP. RESULTS: The mean IOP was 12.65±2.34 mmHg in Beijing and 14.85±3.1 mmHg in Lhasa. The mean AL was 24.61±1.50mm in Beijing, and 24.98±1.45 mm in Lhasa. The IOP and AL showed a significant elevation in highland compared with lowland (P<0.05). The mean K was 43.58±2.25 D in Beijing and 43.56±2.21 D in Lhasa and no significant difference was found in this study (P>0.05). A positive correlation between variance of IOP and ACD was found (r = 0.475, P<0.05) and no correlation between IOP and average BP was noted. CONCLUSIONS: High altitude may lead to a small but significant change in IOP and axial length. However, the shape of the corneal surface was not influenced by the hypobaric and hypoxic conditions.

Air-Puff-Induced Dynamics of Ocular Components Measured with Optical Biometry.

Purpose: To analyze the dynamics of all optical components of the eye and the behavior of the eyeball under air-puff conditions in vivo. To determine the impact of the intraocular pressure (IOP) on the air-puff-induced deformation of the eye. Methods: Twenty eyes of 20 healthy subjects were included in this study. The dynamics of the ocular components, such as the cornea, the crystalline lens, and the retina, was measured by a prototype swept source optical coherence tomography biometer integrated with the air-puff system. The system allows to acquire a series of axial scans at the same location as a function of time with no transverse scanning. Several parameters were extracted from optical coherence tomography data. The IOP was measured using a Goldmann applanation tonometry. The measurements of the eyes were performed before and 2 hours after administration of IOP-reducing drops, namely, 0.2 % brimonidine tartrate. Results: There is a statistically significant correlation of corneal thickness, vitreous depth, and eye length with IOP. The deformation amplitudes of the cornea and the crystalline lens are inversely proportional to the IOP, but statistical significance is achieved only for the cornea. The crystalline lens is displaced without compression, and the return has the form of wobbling. The reduction of IOP level induces corresponding changes in the extracted parameters. Conclusions: Optical biometry combined with air puff provides comprehensive information on the in vivo behavior of all ocular components, including the crystalline lens. Measurement of the axial length dynamics of during deformation enables correcting the deformation for eye retraction.

Bush-like integrin filament networks associated with hyaloid vasculature in murine neonate eyes.

The vitreous of perinatal mice temporarily develops a unique vascular system, called the vasa hyaloidea propria (VHP). Observations showed the vessels possessed an extracellular matrix including the basement membrane in their entire length. Immunostaining of whole mount preparations of VHP with integrin ß1 antibody displayed a bush-like network consisting of long and straight fibers which were associated with the VHP but extended apart from the blood vessels. Electron microscopically, each fiber was composed of a bundle of thin filaments different from collagen fibrils. Macrophages associated with the VHP appeared to be arrested by the integrin bushes. The integrin bushes fragmented and disappeared by postnatal day 10, just before the regression of the VHP. Macrophages were involved in the digestion and clearance of integrin bushes. The vitreous integrin bushes appear to provide a scaffold for architectural maintenance of the hyaloid vessels and macrophages.

In vivo imaging of the fibrillar architecture of the posterior vitreous and its relationship to the premacular bursa, Cloquet's canal, prevascular vitreous fissures, and cisterns.

PURPOSE: To describe the fibrillar architecture of the posterior cortical vitreous and identify variations across eyes of different axial lengths in vivo. METHODS: Sixty-four eyes of 32 subjects were examined with swept-source optical coherence tomography (SS-OCT). Grading of vitreous degeneration, presence of vitreous cisterns/lacunae, posterior hyaloid status, directionality of vitreous fibers and their relations to vitreous spaces, and lamellar reflectivity of the posterior vitreous were assessed. RESULTS: A consistent pattern of fibrillar organization was discovered. Eyewall parallel fibers formed a dense meshwork over the retinal surface and fibers oriented in a perpendicular fashion to this meshwork were found to envelop the various vitreous spaces, intersecting at variable angles of insertion to the eyewall parallel fibers. Lamellar reflectivity suggestive of splitting of the cortical fibrillar meshwork was detected in 27 eyes (42%) with 56% of these eyes demonstrating perpendicularly oriented intersecting fibers. Fifty-six percent of eyes with lamellar reflectivity had an axial length > 25 mm. CONCLUSION: SS-OCT imaging revealed fibrillar organization of the posterior vitreous. Eye wall parallel hyperreflectivity of cortical vitreous was a universal finding. This pattern is suggestive of a splitting of cortical vitreous tissue and may represent a precursor to vitreoschisis. Perpendicular fibers appear to be important constituents of the walls of the various liquid vitreous spaces.

Matching the LenStar optical biometer to A-Scan ultrasonography for use in small animal eyes with application to tree shrews.

We describe an analysis strategy to obtain ultrasonography-matched axial dimensions of small animal eyes using the LenStar biometer. The LenStar optical low-coherence reflectometer is an attractive device for animal research due to its high precision, non-invasiveness, and the ability to measure the axial dimensions of cornea, anterior chamber, lens, vitreous chamber, and axial length. However, this optical biometer was designed for clinical applications in human eyes and its internal analysis provides inaccurate values when used on small eyes due to species-dependent differences in refractive indices and relative axial dimensions. The LenStar uses a near infrared light source to measure optical path lengths (OPLs) that are converted by the LenStar's EyeSuite software into geometrical lengths (GLs) based on the refractive indices and axial dimensions of the human eye. We present a strategy that extracts the OPLs, determines refractive indices specific for the small animal eye of interest and then calculates corrected GLs. The refractive indices are obtained by matching the LenStar values to ultrasonography values in the same eyes. As compared to ultrasounography, we found that the internal calculations of the LenStar underestimate the axial dimensions of all ocular compartments of the tree shrew eye: anterior segment depth by 6.17±4.50%, lens thickness by 1.37±3.06%, vitreous chamber depth by 29.23±2.35%, and axial length by 10.62±1.75%. Using tree shrew-specific refractive indices, the axial dimensions closely matched those measured by ultrasonography for each compartment. Our analysis strategy can be easily translated to other species by obtaining a similar paired data set using ultrasonography and LenStar, and applying our step by step procedures.

Multi-channel MRI segmentation of eye structures and tumors using patient-specific features.

Retinoblastoma and uveal melanoma are fast spreading eye tumors usually diagnosed by using 2D Fundus Image Photography (Fundus) and 2D Ultrasound (US). Diagnosis and treatment planning of such diseases often require additional complementary imaging to confirm the tumor extend via 3D Magnetic Resonance Imaging (MRI). In this context, having automatic segmentations to estimate the size and the distribution of the pathological tissue would be advantageous towards tumor characterization. Until now, the alternative has been the manual delineation of eye structures, a rather time consuming and error-prone task, to be conducted in multiple MRI sequences simultaneously. This situation, and the lack of tools for accurate eye MRI analysis, reduces the interest in MRI beyond the qualitative evaluation of the optic nerve invasion and the confirmation of recurrent malignancies below calcified tumors. In this manuscript, we propose a new framework for the automatic segmentation of eye structures and ocular tumors in multi-sequence MRI. Our key contribution is the introduction of a pathological eye model from which Eye Patient-Specific Features (EPSF) can be computed. These features combine intensity and shape information of pathological tissue while embedded in healthy structures of the eye. We assess our work on a dataset of pathological patient eyes by computing the Dice Similarity Coefficient (DSC) of the sclera, the cornea, the vitreous humor, the lens and the tumor. In addition, we quantitatively show the superior performance of our pathological eye model as compared to the segmentation obtained by using a healthy model (over 4% DSC) and demonstrate the relevance of our EPSF, which improve the final segmentation regardless of the classifier employed.

Distribution of Ocular Component Measures and Refraction in Brazilian School Children.

PURPOSE: To describe ocular component values and refraction in 6-17-year-old school children in Campinas, Brazil. METHODS: To obtain a representative sample, a total of 1100 6-17-year-old public school students in Campinas, Brazil, were randomly selected and divided into groups according to median ages 6 years (range 5-7 years), 10 years (range 9-11 years), 14 years (range 13-15 years), and 17 years (range 16-18 years). Cycloplegic autorefraction and ocular biometry were performed on each child. RESULTS: Parental consent for participation was obtained for 778 of the 1100 students (70.7%). Of these, 440 (56.6%) were female and 330 (44.4%) male. Sex distributions were similar for each median age group. Median age groups 6, 10, 14, and 17 years displayed significant trends of decreasing mean spherical equivalent refraction (SER; 0.96, 0.89, 0.57, and 0.23 diopters, D, respectively), mean lens thickness (3.50, 3.42, 3.41, and 3.45 mm, respectively), and mean lens power (23.6, 22.7, 21.8, and 21.2D, respectively), but significant trends of increasing mean anterior chamber depth (ACD; 3.00, 3.12, 3.16, and 3.15 mm, respectively), mean vitreous chamber depth (VCD; 16.0, 16.4, 16.6, and 16.8 mm, respectively), and mean axial length (22.5, 23.0, 23.2, 23.4 mm, respectively; all p for trend <0.001). CONCLUSIONS: Significant trends towards lower refractive power, increased prevalence of myopia, increased ACD, VCD, and axial length, and decreased lens power were associated with increasing age in these children. There were no significant changes in corneal thickness or corneal curvature.

Importancia del estudio del humor vítreo para el diagnóstico de diabetes mellitus y cetoacidosis diabética post mortem. A propósito de un caso / Importance of the study of the vitreous body for the diagnosis of diabetes mellitus and diabetic ketoacidosis post-mortem. About a case

La diabetes mellitus tipo 1 usualmente debuta con cetoacidosis, una de sus complicaciones que puede llevar a la muerte de forma rápida. Esta condición puede pasar inadvertida, requiriéndose la autopsia médico-legal. Dentro de las muestras de mayor interés en la autopsia se encuentra el humor vítreo, el cual se usa para detección de glucosa y electrolitos, entre otros. Presentamos el caso de una joven de 15 años de edad, sin antecedentes importantes, la cual fallece luego de presentar un cuadro de faringoamigdalitis y los hallazgos anatomopatológicos no permiten identificar la causa de la muerte. Sin embargo, el estudio de humor vítreo revela concentraciones elevadas de glucosa, y la química sanguínea muestra valores de acetona aumentados. Discutimos la importancia de la recolección del humor vítreo para el diagnóstico de enfermedades metabólicas (AU)

Type 1 Diabetes Mellitus usually begins with ketoacidosis, one of its complications that can lead to death quickly. This condition may go unnoticed, requiring medical and legal autopsy. Among the samples of major interest in the autopsy is the vitreous humor, which is used for detection of glucose levels, electrolytes and others. We present the case of a 15-year-old girl with no significant history, who died after presenting with pharyngotonsillitis and the pathological findings did not allow the cause of death to be identified, however, the vitreous humor study revealed elevated glucose levels and Increased blood levels of acetone. We discussed the importance of collecting the vitreous humor for the diagnosis of metabolic diseases (AU)

Microarchitecture of the Vitreous Body: A High-Resolution Optical Coherence Tomography Study.

PURPOSE: To report novel vitreous body microarchitecture findings using high-resolution spectral-domain optical coherence tomography (HR-SD-OCT). DESIGN: Prospective, cross-sectional study. METHODS: Horizontal and vertical retinal cross-sectional images that were 10 mm long were acquired from 17 eyes of 17 young healthy volunteers using HR-SD-OCT with enhanced vitreous imaging (EVI). Images were acquired through the fovea, upper vessel arcade, and lower vessel arcade. RESULTS: Three new findings on vitreous body microarchitecture were found. First, material located between the retina and posterior vitreous cortex was easily detected in 90% of upper and lower vessel arcade scans. Most scans contained hyperreflective dots and multilayered hyperreflective lines around the detached vitreous cortex. Second, a lamellar structure was observed in the vitreous body in 70%-80% of all scans, excluding vertical scans of the upper arcade vessel area. Third, tubular zones of hypodensity were detected in >80% of scans, excluding horizontal scans of the macula. Interestingly, the location of tubular zones of hypodensity seemed to correspond with the location of retinal vessels. Subject age, refractive error, and axial length were not significantly different in scans with and without material between the retina and vitreous, lamellar structures, and tubular zones of hypodensity. CONCLUSIONS: The microarchitecture of the vitreous body can be visualized using HR-SD-OCT and EVI.

Vitreous anatomy and the vitreomacular correlation.

The presence of a posterior precortical vitreous pocket, referred to as a precortical pocket, implies that the vitreous cortex is formed into a collagen sheet separated from the gel in the macula. Along with strong vitreoretinal attachment at the fovea, the precortical pocket plays a role in perifoveal posterior vitreous detachments, which may lead to macular holes, premacular membranes, and ring-shaped proliferation in diabetic retinopathy. I and my colleagues published pioneer studies of the vitreous in postmortem eyes. Here, the role of the precortical pocket in various vitreoretinal interface diseases is discussed. Swept-source optical coherence tomography showed development of the precortical pocket, the connecting channel, and Cloquet's canal during early childhood. These findings raised the possibility that aqueous humor may drain into the precortical pocket. The physiologic role of the drainage route is also discussed. Crosstalk between the anterior chamber and macula is an attractive hypothesis and remains to be elucidated.

RETINOCHOROIDAL MORPHOLOGY DESCRIBED BY WIDE-FIELD MONTAGE IMAGING OF SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY.

PURPOSE: To present baseline images of the vitreous, retina, and choroid from the macula to the periphery in normal patients using a novel montaging technique of spectral domain optical coherence tomography. METHODS: Twenty-six normal eyes of 22 healthy volunteers were enrolled in this study. Montaged images of four radial optical coherence tomography scans through the fovea were obtained from each subject. RESULTS: In the macula, there were six identifiable retinal layers as well as four bands in the outer retina. In the periphery, the ganglion cell layer was not identifiable. The external limiting membrane, the second band, and the retinal pigment epithelium were continuously delineated from the macula to the periphery. The third band was not visible in the periphery. CONCLUSION: Spectral domain optical coherence tomography montaged images provide wide-angle images of the vitreous, retina, and choroid, allowing for evaluation of peripheral findings and examination of relationships between peripheral and posterior disease. The maximum scan length achieved here was 36 mm. The scan length is approximately three times than that provided by conventional posterior scanning and is consistent with known dimensions of the eye. This method is achievable with current commercially available devices and may contribute to decision making in clinical practice.

Effects of Birth Weight on Anterior Segment Measurements in Full-Term Children Without Low Birth Weight by Dual-Scheimpflug Analyzer.

PURPOSE: To evaluate the effects of birth weight on ocular anterior segment parameters in full-term children without low birth weight using the Galilei Dual-Scheimpflug Analyzer. DESIGN: Retrospective cohort study. METHODS: The right eyes from 110 healthy children, 3-6 years of age, were scanned with the Galilei Dual-Scheimpflug Analyzer. A total of 78 eyes were measured in full-term children with birth weight of >2500 g. Central, paracentral, pericentral, and the thinnest corneal thicknesses; anterior and posterior keratometry (average, steep, flat); axial curvatures; asphericity of cornea; anterior chamber depth and volume; and iridocorneal angle values were measured. Axial length, lens thickness, and vitreous length were obtained by ultrasound biometry. RESULTS: The mean age of children was 55.86 ± 12.52 (mean ± SD) months. Mean birth weight and gestational age were 3426.3 ± 545 g and 39.4 ± 1.2 weeks, respectively. Although lens thickness, vitreous length, axial length, and anterior chamber volume were moderately correlated with birth weight (P < .05), there was no relationship between birth weight and anterior chamber depth. With the exception of pericentral corneal thickness, all regions of corneal thicknesses were correlated with birth weight (P < .05). Birth weight was negatively correlated with anterior curvature (P < .05) and had no relationship to posterior curvature. While central and paracentral axial curvatures correlated with birth weight (P < .05), pericentral axial curvature did not. CONCLUSION: Preschoolers who were born heavier had thicker cornea and lens, longer axial length, and flatter corneal curve. The thicknesses and axial curves of central cornea within 7 mm may be particularly associated with birth weight.

The relationship of birth weight, gestational age, and postmenstrual age with ocular biometry parameters in premature infants.

PURPOSE: To analyze ocular biometry parameters and evaluate their relationship with gestational age, birth weight, and postmenstrual age in prematurely born infants. METHODS: The right eyes of 361 premature infants born before the 36th gestational week were evaluated. Birth weight, gestational week, and gender were recorded. An A-scan Biometer was used for obtaining axial measurements, including anterior chamber depth, lens thickness, vitreous length, and total axial length. RESULTS: Gestational age and birth weight values ranged from 23 to 36 weeks and from 560 to 2,670 g, respectively. The mean gestational age and birth weight were 30.8 ± 2.8 weeks and 1,497.9 ± 483.6 g, respectively. During the first examination (4-5 weeks of postnatal age), birth weight and gestational age of the infants correlated significantly and positively with lens thickness, vitreous length, and axial length (r>0.5, p<0.001), but not with anterior chamber depth (r<0.5). Increased vitreous and axial lengths correlated significantly with increasing postmenstrual age of the infants (r=0.669, p<0.001; r=0.845, p<0.001, respectively). CONCLUSIONS: Lens thickness, vitreous length, and axial length, but not anterior chamber depth, were significantly correlated with birth weight and gestational age. All four parameters increased with increasing postmenstrual age, with higher correlations for vitreous and axial lengths than for anterior chamber depth and lens thickness. It was concluded that axial elongation resulted primarily from increasing posterior chamber length.