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Purpose To investigate the choriocapillaris in children with amblyopia, using optical coherence tomography angiography (OCT-A). Methods Patients with amblyopia and age-matched controls were prospectively imaged using OCT-A. On OCT-A, the choriocapillaris measures 30 μm starting 31 μm posterior to the retinal pigment epithelium. The section of choriocapillaris under superficial retinal vessels was excluded from analysis to avoid shadowing or projection artifacts. The main outcome measure was choriocapillaris vessel density. Secondary outcome measures were foveal macular thickness and parafoveal macular thickness. Results A total of 20 eyes of 16 patients with amblyopia and 25 eyes of 25 controls were included. Mean age of amblyopic subjects was 7.6 ± 3.6 years; of controls, 9.3 ± 2.2 years (P = 0.10). Mean refractive error of subjects was 4.3 ± 6.2 D; of controls, 0.0 ± 1.6 D (P = 0.004). Mean choriocapillaris vessel density was 74.8 ± 5.8 in the amblyopic group and 71.1 ± 3.6 in the control group, which was significant even after adjusting for age and refractive error (P = 0.012). There was no difference between groups in foveal macular thickness or parafoveal macular thickness; however, outer parafoveal macular thickness (the inner boundary of the inner nuclear layer to the retinal pigment epithelium outer boundary) was significantly greater in amblyopic eyes than in control eyes, even after adjusting for age and refractive error (203 ± 11 μm and 189 ± 12 μm, resp. [ P = 0.014]). Conclusions In our study cohort, amblyopic eyes were found to have increased choriocapillaris vessel density as well as a greater outer parafoveal macular thickness, which may be due to alterations in outer retinal maturation. [ABSTRACT FROM AUTHOR]

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Abstract: Purpose: Defocus imposed to the periphery of the visual field can affect the development of foveal/central refractive errors. To make use of this observation, lenses can be designed to reduce myopia progression, but it is important to know which power profiles of the lenses are most effective. We have studied this question in chickens. Methods: Sixty male white leghorn chickens were used. From day 7 after hatching, they were treated for 5days either with full field −7D or +7D lenses, with −7D lenses with a 4mm central hole, with hemi-field lenses of the same power, or with two different types of radial refractive gradient (RRG) lenses with increasing positive power from the center to the periphery, which were designed by Rodenstock GmbH, Munich, Germany. A macro file was written for “ImageJ” to trace and average the outlines of several excised eyes after treatment. Shapes of fellow control eyes and lens-treated eyes were compared in the horizontal and vertical meridians. Refractions were determined at −45°, 0°, and 45° over the horizontal visual field, at the beginning and at the end of experiments, using automated infrared photoretinoscopy. Results: (1) Eye length, as determined by the new automated eye shape tracing technique, was well correlated with A-scan ultrasound data. (2) The effects of previously tested lens designs were reproduced with the new tracing technique. Full field lenses were by far the most effective (−7D: external axial length +0.24mm with an increase in eye volume of about 6%, +7D: −0.08mm, with a decrease in eye volume of about 2%). Hemi-field lenses and negative lenses with a 4mm central hole induced conspicuous local changes in eye shape. (3) The first type of RRG lenses with a plano zone of about 4mm (equivalent to about ±12.52° in the visual field for a vertex distance of 5mm) had no apparent effect on central refractions but induced small hyperopic shifts in the periphery, more significant in the temporal retina (+1.70±1.70D, p <0.001, paired t-test to untreated fellow eyes). The second type of RRG lenses with a small plano zone of 2mm (equivalent to ±6.34°) induced peripheral hyperopia but also changed the central refraction (temporal retina +1.50±1.17D, p <0.001, central retina +0.77±1.15D, p <0.01, nasal retina +1.47±1.35D, p <0.001, paired t-test to untreated control eyes). Conclusions: In the afoveate chick, RRG lenses have an effect on central refraction and eye growth only if the central plano zone is small (<4mm). For the second type of RRG lens with a central plano zone of about 2mm, inhibitory effects on eye growth were detected in both the center and periphery even though the optical power of the lenses in the periphery was low. [Copyright &y& Elsevier]

Abstract: During the developmental process of emmetropization evidence shows that visual feedback guides the eye as it approaches a refractive state close to zero, or slightly hyperopic. How this “set-point” is internally defined, in the presence of continuous shifts of the focal plane with different viewing distances and accommodation, remains unclear. Minimizing defocus blur over time should produce similar end-point refractions in different individuals. However, we found that individual chickens display considerable variability in their set-point refractive states, despite that they all had the same visual experience. This variability is not random since the refractions in both eyes were highly correlated – even though it is known that they can emmetropize independently. Furthermore, if chicks underwent a period of experimentally induced ametropia, they returned to their individual set-point refractions during recovery (correlation of the refractions before treatment versus after recovery: n =19 chicks, 38 eyes, left eyes: slope 1.01, R=0.860; right eyes: slope 0.85, R = 0.610, p <0.001, linear regression). Also, the induced deprivation myopia was correlated in both eyes (n =18 chicks, 36 eyes, p <0.01, orthogonal regression). If chicks were treated with spectacle lenses, the compensatory changes in refraction were, on average, appropriate but individual chicks displayed variable responses. Again, the refractions of both eyes remained correlated (negative lenses, n =18 chicks, 36 eyes, slope 0.89, R =0.504, p <0.01, positive lenses: n =21 chicks, 42 eyes, slope 1.14, R =0.791, p <0.001). The amount of deprivation myopia that developed in two successive treatment cycles, with an intermittent period of recovery, was not correlated; only vitreous chamber growth was almost significantly correlated in both cycles (n =7 chicks, 14 eyes; p <0.05). The amounts of ametropia and vitreous chamber changes induced in two successive cycles of treatment, first with lenses and then with diffusers, were also not correlated, suggesting that the “gains of lens compensation” are different from those in deprivation myopia. In summary, (1) there appears to be an endogenous, possibly genetic, definition of the set-point of emmetropization in each individual, which is similar in both eyes, (2) visual conditions that induce ametropia produce variable changes in refractions, with high correlations between both eyes, (3) overall, the “gain of emmetropization” appears only weakly controlled by endogenous factors. [Copyright &y& Elsevier]

Purpose To characterize choroidal thickness and choroidal reflectivity in the eyes of patients with birdshot chorioretinopathy (BSCR). Design Cross-sectional observational study. Participants Two hundred twenty BSCR patients and 59 healthy controls. Methods Patients with BSCR and healthy controls underwent imaging of the macula in both eyes with a swept-source optical coherence tomography device (DRI-OCT1 Atlantis; Topcon). Images were exported from the device, and analysis was performed by 2 graders in the Doheny Image Reading Center using Image J software. The choroidal thickness at the foveal center was measured. In addition, the inner and outer boundaries of the choroid and retinal pigment epithelium (RPE) as well as the inner retinal surface all were segmented to allow the brightness and reflectivity of the pixels in the choroid, RPE band, and overlying vitreous to be quantified. An adjusted or normalized choroidal reflectivity, with the RPE as the bright reference standard and the vitreous as the dark reference standard, was computed using the formula: normalized choroidal reflectivity = (choroidal reflectivity−vitreous reflectivity)/RPE reflectivity. Main Outcome Measures Choroidal reflectivity and choroidal thickness. Results Three hundred eighty-six eyes in the BSCR group and 59 eyes in the control group were included in this analysis. Higher choroidal reflectivity and lower choroidal thickness were documented in inactive BSCR patients compared with active BSCR and controls ( P < 0.01). Active BSCR patients showed lower choroidal thickness compared with controls ( P < 0.01). There was a negative correlation between choroidal reflectivity and choroidal thickness ( r = −0.793; P < 0.001). On multiple regression analysis, choroidal thickness, age, and disease duration (all P < 0.01) all were significant predictors of choroidal reflectivity. Conclusions Choroidal reflectivity and choroidal thickness changes are evident in active and inactive BSCR patients. Novel choroidal parameters such as choroidal reflectivity may warrant further study in the setting of BSCR. [ABSTRACT FROM AUTHOR]