Ablation of mpeg+ Macrophages Exacerbates mfrp-Related Hyperopia.

Purpose: Proper refractive development of the eye, termed emmetropization, is critical for focused vision and is impacted by both genetic determinants and several visual environment factors. Improper emmetropization caused by genetic variants can lead to congenital hyperopia, which is characterized by small eyes and relatively short ocular axial length. To date, variants in only four genes have been firmly associated with human hyperopia, one of which is MFRP. Zebrafish mfrp mutants also have hyperopia and, similar to reports in mice, exhibit increased macrophage recruitment to the retina. The goal of this research was to examine the effects of macrophage ablation on emmetropization and mfrp-related hyperopia. Methods: We utilized a chemically inducible, cell-specific ablation system to deplete macrophages in both wild-type and mfrp mutant zebrafish. Spectral-domain optical coherence tomography was then used to measure components of the eye and determine relative refractive state. Histology, immunohistochemistry, and transmission electron microscopy were used to further study the eyes. Results: Although macrophage ablation does not cause significant changes to the relative refractive state of wild-type zebrafish, macrophage ablation in mfrp mutants significantly exacerbates their hyperopic phenotype, resulting in a relative refractive error 1.3 times higher than that of non-ablated mfrp siblings. Conclusions: Genetic inactivation of mfrp leads to hyperopia, as well as abnormal accumulation of macrophages in the retina. Ablation of the mpeg1-positive macrophage population exacerbates the hyperopia, suggesting that macrophages may be recruited in an effort help preserve emmetropization and ameliorate hyperopia.

The Role of Dopamine in Emmetropization Modulated by Wavelength and Temporal Frequency in Guinea Pigs.

Purpose: Wavelength and temporal frequency have been found to influence refractive development. This study investigated whether retinal dopamine (DA) plays a role in these processes. Methods: Guinea pigs were randomly divided into nine groups that received different lighting conditions for 4 weeks, as follows: white, green, or blue light at 0, 0.5, or 20.0 Hz. Refractions and axial lengths were measured using streak retinoscopy and A-scan ultrasound imaging. DA and its metabolites were measured by high-pressure liquid chromatography-electrochemical detection. Results: At 0 Hz, green and blue light produced myopic and hyperopic shifts compared with that of white light. At 0.5 Hz, no significant changes were observed compared with those of green or blue light at 0 Hz, whereas white light at 0.5 Hz induced a myopic shift compared with white light at 0 or 20 Hz. At 20 Hz, green and blue light acted like white light. Among all levels of DA and its metabolites, only vitreous 3, 4-dihydroxyphenylacetic acid (DOPAC) levels and retinal DOPAC/DA ratios were dependent on wavelength, frequency, and their interaction. Specifically, retinal DOPAC/DA ratios were positively correlated with refractions in white and green light conditions. However, blue light (0, 0.5, and 20.0 Hz) produced hyperopic shifts but decreased vitreous DOPAC levels and retinal DOPAC/DA ratios. Conclusions: The retinal DOPAC/DA ratio, indicating the metabolic efficiency of DA, is correlated with ocular growth. It may underlie myopic shifts from light exposure with a long wavelength and low temporal frequency. However, different biochemical pathways may contribute to the hyperopic shifts from short wavelength light.

Meridional Anisotropy of Foveal and Peripheral Resolution Acuity in Adults With Emmetropia, Myopia, and Astigmatism.

Purpose: To quantify astigmatism-related meridional anisotropy in visual resolution at central, nasal, and inferior visual fields. Methods: Three groups of young adults (range, 18-30 years) with corrected-to-normal visual acuity (logMAR 0) were recruited: (1) myopic astigmats (MA): spherical-equivalent error (SE) < -0.75D, with-the-rule astigmatism ≥ 2.00D, n = 19; (2) simple myopes (SM): SE < -0.75D, astigmatism ≤ 0.50D, n = 20; and (3) emmetropes (EM): SE ± 0.50D, astigmatism ≤ 0.50D, n = 14. Resolution acuity was measured for the horizontal and vertical gratings at central and peripheral visual fields (eccentricity: 15°) using a 3-down 1-up staircase paradigm. On- and off-axis refractive errors were corrected by ophthalmic lenses. Results: The MA group exhibited meridional anisotropy preferring vertical gratings. At the central field, the MA group had better resolution acuity for vertical than horizontal gratings, and their resolution acuity for horizontal gratings was significantly worse than the SM and EM groups. At peripheral visual fields, both the SM and EM groups showed better resolution acuity for the radial (i.e., nasal field: horizontal gratings; inferior field: vertical gratings) than tangential orientation. However, the MA group tended to have better resolution acuity for the tangential orientation (i.e., vertical gratings), and their resolution acuity for horizontal gratings was significantly lower than the SM and EM groups at the nasal field. No significant differences were found in the inferior field among the three groups. Conclusions: This study provided evidence of astigmatism-related meridional anisotropy at the fovea and nasal visual fields, underscoring the significant impact of astigmatism on orientation-dependent visual functions.

The Role of Retinal Connexins Cx36 and Horizontal Cell Coupling in Emmetropization in Guinea Pigs.

Purpose: The purpose of this study was to determine whether retinal gap junctions (GJs) via connexin 36 (Cx36, mediating coupling of many retinal cell types) and horizontal cell (HC-HC) coupling, are involved in emmetropization. Methods: Guinea pigs (3 weeks old) were monocularly form deprived (FD) or raised without FD (in normal visual [NV] environment) for 2 days or 4 weeks; alternatively, they wore a -4 D lens (hyperopic defocus [HD]) or 0 D lens for 2 days or 1 week. FD and NV eyes received daily subconjunctival injections of a nonspecific GJ-uncoupling agent, 18-ß-Glycyrrhetinic Acid (18-ß-GA). The amounts of total Cx36 and of phosphorylated Cx36 (P-Cx36; activated state that increases cell-cell coupling), in the inner and outer plexiform layers (IPLs and OPLs), were evaluated by quantitative immunofluorescence (IF), and HC-HC coupling was evaluated by cut-loading with neurobiotin. Results: FD per se (excluding effect of light-attenuation) increased HC-HC coupling in OPL, whereas HD did not affect it. HD for 2 days or 1 week had no significant effect on retinal content of Cx36 or P-Cx36. FD for 4 weeks decreased the total amounts of Cx36 and P-Cx36, and the P-Cx36/Cx36 ratio, in the IPL. Subconjunctival 18-ß-GA induced myopia in NV eyes and increased the myopic shifts in FD eyes, while reducing the amounts of Cx36 and P-Cx36 in both the IPL and OPL. Conclusions: These results suggest that cell-cell coupling via GJs containing Cx36 (particularly those in the IPL) plays a role in emmetropization and form deprivation myopia (FDM) in mammals. Although both FD and 18-ß-GA induced myopia, they had opposite effects on HC-HC coupling. These findings suggest that HC-HC coupling in the OPL might not play a significant role in emmetropization and myopia development.

Eyes grow towards mild hyperopia rather than emmetropia in Chinese preschool children.

PURPOSE: To document one-year changes in refraction and refractive components in preschool children. METHODS: Children, 3-5 years old, in the Jiading District, Shanghai, were followed for one year. At each visit, axial length (AL), refraction under cycloplegia (1% cyclopentolate), spherical dioptres (DS), cylinder dioptres (DC), spherical equivalent refraction (SER) and corneal curvature radius (CR) were measured. RESULTS: The study included 458 right eyes of 458 children. The mean changes in DS, DC and SER were 0.02 ± 0.35 D, -0.02 ± 0.33 D and 0.01 ± 0.37 D, while the mean changes in AL, CR and lens power (LP) were 0.27 ± 0.10 mm, 0.00 ± 0.04 mm and - 0.93 ± 0.49 D. The change in the SER was linearly correlated with the baseline SER (coefficient = -0.147, p < 0.001). When the baseline SER was at 1.05 D (95% CI = 0.21 to 2.16), the change in SER was 0 D. The baseline SER was also linearly associated with the change in LP (coefficient = 0.104, p = 0.013), but not with the change in AL (p = 0.957) or with the change in CR (p = 0.263). CONCLUSION: In eyes with a baseline SER less than +1.00 D, LP loss was higher compared to axial elongation, leading to hyperopic shifts in refraction, whereas for those with baseline SER over this range, loss of LP compared to axial elongation was reduced, leading to myopic shifts. This model indicated the homeostasis of human refraction and explained how refractive development leads to a preferred state of mild hyperopia.

Spectral composition of artificial illuminants and their effect on eye growth in chicks.

In broadband light, longitudinal chromatic aberration (LCA) provides emmetropization signals from both wavelength defocus and the resulting chromatic cues. Indoor illuminants vary in their spectral output, potentially limiting the signals from LCA. Our aim is to investigate the effect that artificial illuminants with different spectral outputs have on chick emmetropization with and without low temporal frequency modulation. In Experiment 1, two-week-old chicks were exposed to 0.2 Hz, square-wave luminance modulation for 3 days. There were 4 spectral conditions: LED strips that simulated General Electric (GE) LED "Soft" (n = 13), GE LED "Daylight" (n = 12), a novel "Equal" condition (n = 12), and a novel "High S" condition (n = 10). These conditions were all tested at a mean level of 985 lux. In Experiment 2, the effect of intensity on the "Equal" condition was tested at two other light levels (70 lux: n = 10; 680 lux: n = 7). In Experiment 3, the effect of temporal modulation on the "Equal" condition was tested by comparing the 0.2 Hz condition with 0 Hz (steady). Significant differences were found in axial growth across lighting conditions. At 985 lux, birds exposed to the "Equal" condition showed a greater reduction in axial growth (both p < 0.01) and a greater hyperopic shift compared to "Soft" and "Daylight" (both p < 0.01). The "High S" birds experienced more axial growth compared to "Equal" (p < 0.01) but less than in "Soft" and "Daylight" (p < 0.01). Axial changes in "Equal" were only observed at 985 lux with 0.2 Hz temporal modulation, and not with lower light levels or steady light. We conclude that axial growth and refraction were dependent on the lighting condition in a manner predicted by wavelength defocus signals arising from LCA.

Associations between visual function and magnitude of refractive error for emmetropic to moderately hyperopic 4- and 5-year-old children in the Vision in Preschoolers - Hyperopia in Preschoolers Study.

PURPOSE: To evaluate associations between visual function and the level of uncorrected hyperopia in 4- and 5-year-old children without strabismus or amblyopia. METHODS: Children with spherical equivalent (SE) cycloplegic refractive error of -0.75 to +6.00 on eligibility testing for the Vision in Preschoolers-Hyperopia in Preschoolers (VIP-HIP) study were included. Children were grouped as emmetropic (<1D SE myopia or hyperopia), low hyperopic (+1 to <+3D SE) or moderate hyperopic (+3 to +6D SE). Children with anisometropia or astigmatism (≥1D), amblyopia or strabismus were excluded. Visual functions assessed were monocular distance visual acuity (VA) and binocular near VA with crowded HOTV charts, accommodative lag using the Monocular Estimation Method and near stereoacuity by 'Preschool Assessment of Stereopsis with a Smile'. Visual functions were compared as continuous measures among refractive error groups. RESULTS: 554 children (mean age 58 months) were included in the analysis. Mean SE (SD) {N} for emmetropia, low and moderate hyperopia were +0.52D (0.49) {N = 270}, +2.18D (0.57) {N = 171} and +3.95D (0.78) {N = 113}, respectively. There was a consistent trend of poorer visual function with increasing hyperopia (p < 0.001). Although all children had age-normal distance VA, logMAR (Snellen) VA of 0.00 (6/6) or better was achieved (distance, near) among more emmetropic (52%, 26%) and low hyperopic (47%, 15%) children than moderate hyperopes (25%, 9%). Mean (SD) distance logMAR VA declined from emmetropic 0.05 (0.10), to low hyperopic 0.06 (0.10) to moderately hyperopic children 0.12 (0.11) (p < 0.001); A mild progressive decrease in near VA also was observed from the emmetropic 0.13 (0.11) to low hyperopic 0.15 (0.10) to moderate hyperopic 0.19 (0.11) groups, (p < 0.001). Accommodative responses showed an increased lag with increasing hyperopia (ρ = 0.50, p < 0.001). Median near stereoacuity for emmetropes, low and moderate hyperopes was 40, 60 and 120 sec arc, respectively. The percentage of these groups with no reduced near visual functions was 83%, 61%, and 34%, respectively. CONCLUSIONS: Decreasing visual function was associated with increasing hyperopia in 4- and 5-year-olds without strabismus or amblyopia. As hyperopia with reduced visual function has been associated with early literacy deficits, near visual function should be evaluated in these children.

Myopia, corneal endothelial cell density and morphology in a Japanese population-based cross-sectional study: the JPHC-NEXT Eye Study.

This population-based cross-sectional study was performed to determine the mean corneal endothelial cell density (ECD), coefficient of variation (CV), and hexagonality (HEX), and their associations with myopia in Japanese adults living in Chikusei city. Of 7109 participants with available data, 5713 (2331 male and 3382 female) participants were eligible for analysis. After assessing the relationship between participant characteristics and spherical equivalent refraction (SER), the association of SER with the abnormal value of ECD (< 2000 cells/mm), CV (≥ 0.40), and HEX (≤ 50%) were determined using the logistic regression models adjusting for potential confounders (age, intraocular pressure, keratometric power, height, and antihypertensive drug use). In male participants, there was no statistically significant relationships between SER and endothelial parameters. In female participants, compared to emmetropia, SER ≤ - 6 D had significantly higher odds ratio (OR) of having the abnormal value of CV (OR = 2.07, 95% confidence interval [CI] 1.39-3.10) and HEX (OR = 2.04, 95% CI 1.29-3.23), adjusted for potential confounders, indicating that the high myopia was associated with the abnormal values of CV and HEX. Further adjustment for contact lenses wear partly attenuated these associations. Association between the SER and ECD was not detected.

The blur horopter: Retinal conjugate surface in binocular viewing.

From measurements of wavefront aberrations in 16 emmetropic eyes, we calculated where objects in the world create best-focused images across the central 27\(^\circ\) (diameter) of the retina. This is the retinal conjugate surface. We calculated how the surface changes as the eye accommodates from near to far and found that it mostly maintains its shape. The conjugate surface is pitched top-back, meaning that the upper visual field is relatively hyperopic compared to the lower field. We extended the measurements of best image quality into the binocular domain by considering how the retinal conjugate surfaces for the two eyes overlap in binocular viewing. We call this binocular extension the blur horopter. We show that in combining the two images with possibly different sharpness, the visual system creates a larger depth of field of apparently sharp images than occurs with monocular viewing. We examined similarities between the blur horopter and its analog in binocular vision: the binocular horopter. We compared these horopters to the statistics of the natural visual environment. The binocular horopter and scene statistics are strikingly similar. The blur horopter and natural statistics are qualitatively, but not quantitatively, similar. Finally, we used the measurements to refine what is commonly referred to as the zone of clear single binocular vision.

Emmetropic, But Not Myopic Human Eyes Distinguish Positive Defocus From Calculated Blur.

Purpose: Defocus blur imposed by positive lenses can induce hyperopia, whereas blur imposed by diffusers induces deprivation myopia. It is unclear whether the retina can distinguish between both conditions when the magnitude of blur is matched. Methods: Ten emmetropic (average 0.0 ± 0.3 diopters [D]) and 10 subjects with myopia (-2.7 ± 0.9 D; 24 ± 4 years) watched a movie on a large screen (65 inches at 2 meters (m) distance. The movie was presented either unfiltered ("control"), with calculated low-pass filtering equivalent to a defocus of 2.5 D, or with binocular real optical defocus of +2.5 D. Spatial filtering was done in real-time by software written in Visual C++. Axial length was followed with the Lenstar LS-900 with autopositioning system. Results: Watching unfiltered movies ("control") caused no changes in axial length. In emmetropes, watching movies with calculated defocus caused axial eye elongation (+9.8 ± 7.6 µm) while watching movies with real positive defocus caused shorter eyes (-8.8 ± 9.2 µm; difference between both P < 0.0001). In addition, in myopes, calculated defocus caused longer eyes (+8.4 ± 9.0 µm, P = 0.001). Strikingly, myopic eyes became also longer with positive defocus (+9.1 ± 11.2 µm, P = 0.02). The difference between emmetropic and myopic eyes was highly significant (-8.8 ± 9.2 µm vs. +9.1 ± 11.2 µm, respectively, P = 0.001). Conclusions: (1) In emmetropic human subjects, the retina is able to distinguish between real positive defocus and calculated defocus even when the modulation transfer function was matched, (2) in myopic eyes, the retina no longer distinguishes between both conditions because the eyes became longer in both cases. Results suggest that the retina in a myopic eye has reduced ability to detect positive defocus.

Tree shrews do not maintain emmetropia in initially-focused narrow-band cyan light.

We asked if emmetropia, achieved in broadband colony lighting, is maintained in narrow-band cyan light that is well focused in the emmetropic eye, but does not allow for guidance from longitudinal chromatic aberrations (LCA) and offers minimal perceptual color cues. In addition, we examined the response to a -5 D lens in this lighting. Seven tree shrews from different litters were initially housed in broad-spectrum colony lighting. At 24 ± 1 days after eye opening (Days of Visual Experience, DVE) they were housed for 11 days in ambient narrow-band cyan light (peak wavelength 505 ± 17 nm) selected because it is in focus in an emmetropic eye. Perceptually, monochromatic light at 505 nm cannot be distinguished from white by tree shrews. While in cyan light, each animal wore a monocular -5 D lens (Cyan -5 D eyes). The fellow eye was the Cyan no-lens eye. Daily awake non-cycloplegic measures were taken with an autorefractor (refractive state) and with optical low-coherence optical interferometry (axial component dimensions). These measures were compared with the values of animals raised in standard colony fluorescent lighting: an untreated group (n = 7), groups with monocular form deprivation (n = 7) or monocular -5 D lens treatment (n = 5), or that experienced 10 days in total darkness (n = 5). Refractive state at the onset of cyan light treatment was low hyperopia, (mean ± SEM) 1.4 ± 0.4 diopters. During treatment, the Cyan no-lens eyes became myopic (-2.9 ± 0.3 D) whereas colony lighting animals remained slightly hyperopic (1.0 ± 0.2 D). Initially, refractions of the Cyan -5 D eyes paralleled the Cyan no-lens eyes. After six days, they gradually became more myopic than the Cyan no-lens eyes; at the end of treatment, the refractions were -5.4 ± 0.3 D, a difference of -2.5 D from the Cyan no-lens eyes. When returned to colony lighting at 35 ± 1 DVE, the no-lens eye refractions rapidly recovered towards emmetropia but, as expected, the refraction of the -5 D eyes remained near -5 D. Vitreous chamber depth in both eyes was consistent with the refractive changes. In narrow-band cyan lighting the emmetropization mechanism did not maintain emmetropia even though the light initially was well focused. We suggest that, as the eyes diverged from emmetropia, there were insufficient LCA cues for the emmetropization mechanism to utilize the developing myopic refractive error in order to guide the eyes back to emmetropia. However, the increased myopia in the Cyan -5 D eyes in the narrow-band light indicates that the emmetropization mechanism nonetheless detected the presence of the lens-induced refractive error and responded with increased axial elongation that partly compensated for the negative-power lens. These data support the conclusion that the emmetropization mechanism cannot maintain emmetropia in narrow-band lighting. The additional myopia produced in eyes with the -5 D lens shows that the emmetropization mechanism responds to multiple defocus-related cues, even under conditions where it is unable to use them to maintain emmetropia.

Topically instilled caffeine selectively alters emmetropizing responses in infant rhesus monkeys.

Oral administration of the adenosine receptor (ADOR) antagonist, 7-methylxanthine (7-MX), reduces both form-deprivation and lens-induced myopia in mammalian animal models. We investigated whether topically instilled caffeine, another non-selective ADOR antagonist, retards vision-induced axial elongation in monkeys. Beginning at 24 days of age, a 1.4% caffeine solution was instilled in both eyes of 14 rhesus monkeys twice each day until the age of 135 days. Concurrent with the caffeine regimen, the monkeys were fitted with helmets that held either -3 D (-3D/pl caffeine, n = 8) or +3 D spectacle lenses (+3D/pl caffeine, n = 6) in front of their lens-treated eyes and zero-powered lenses in front of their fellow-control eyes. Refractive errors and ocular dimensions were measured at baseline and periodically throughout the lens-rearing period. Control data were obtained from 8 vehicle-treated animals also reared with monocular -3 D spectacles (-3D/pl vehicle). In addition, historical comparison data were available for otherwise untreated lens-reared controls (-3D/pl controls, n = 20; +3D/pl controls, n = 9) and 41 normal monkeys. The vehicle controls and the untreated lens-reared controls consistently developed compensating axial anisometropias (-3D/pl vehicle = -1.44 ± 1.04 D; -3D/pl controls = -1.85 ± 1.20 D; +3D/pl controls = +1.92 ± 0.56 D). The caffeine regime did not interfere with hyperopic compensation in response to +3 D of anisometropia (+1.93 ± 0.82 D), however, it reduced the likelihood that animals would compensate for -3 D of anisometropia (+0.58 ± 1.82 D). The caffeine regimen also promoted hyperopic shifts in both the lens-treated and fellow-control eyes; 26 of the 28 caffeine-treated eyes became more hyperopic than the median normal monkey (mean (±SD) relative hyperopia = +2.27 ± 1.65 D; range = +0.31 to +6.37 D). The effects of topical caffeine on refractive development, which were qualitatively similar to those produced by oral administration of 7-MX, indicate that ADOR antagonists have potential in treatment strategies for preventing and/or reducing myopia progression.

Anterior scleral thickness and shape changes with different levels of simulated convergence.

PURPOSE: Convergence plays a fundamental role in the performance of near visual tasks. We measured the effect of two levels of convergence on anterior scleral thickness and shape in emmetropes, low to moderate myopes and high myopes. METHODS: Forty-five healthy young adults aged between 18 and 35 years including 15 emmetropes, 15 low/moderate myopes, and 15 high myopes were recruited. Anterior segment optical coherence tomography and eye surface profilometry were used to evaluate the anterior scleral thickness (nasal only, n = 42) and shape (n = 40), before and during two visual tasks involving 9° and 18° convergence, in those participants with complete and reliable data. RESULTS: Convergence led to a thickening of the total anterior eye wall (5.9 ± 1.4 µm) and forward movement (10 ± 2 µm) of the nasal anterior scleral surface (both p < 0.001). Larger changes were found at 18° than at 9° convergence and in more peripheral nasal scleral regions. There was a significant association between total wall thickening and forward movement of the scleral surface. Refractive group was not a significant main effect, but there were significant interactions between refractive group and the thickness changes with convergence in different scleral regions. CONCLUSION: During convergence, the biomechanical forces acting on the eye lead to nasal anterior scleral thickening and forward movement of the nasal scleral surface.

Effects of physical exercise on macular vessel density and choroidal thickness in children.

We used swept-source (SS) optical coherence tomography (OCT) and OCT angiography (OCTA) to investigate the effects of moderate physical exercise on retinal and choroidal vessel densities (VDs) and thicknesses in children. One eye in each of 40 myopic children (mean age, 11.70 years) and 18 emmetropic children (mean age, 11.06 years) were included. SS-OCT 6 × 6-mm radial scans and SS-OCTA 3 × 3-mm images were centered on the macula. Heart rate (HR), systolic and diastolic blood pressure, and intraocular pressure (IOP) were recorded before and immediately after a 20-min stationary cycling exercise and after a 30-min rest. The subfoveal choroidal thickness (SFCT), choroidal thickness (CT), and VD at the superficial and deep retinal layers, choriocapillaris, and deeper choroidal vessels were determined. SFCT and CT were significantly lower at all locations immediately after exercise (p < 0.001) and did not fully recover after rest (p < 0.05). VD was lower in the deep retinal layer after exercise (p = 0.02) and higher in the superficial layer after rest (p = 0.03) in myopic eyes while it was higher in the superficial (p < 0.01) and deep layer (p < 0.01) after rest in emmetropic eyes. No significant exercise-related changes in the superficial retinal VD, choroidal VD, or IOP were observed. ΔCT% and ΔSFCT% were significantly correlated with increases in HR in myopic group (p = 0.04 and p = 0.03, respectively). Exercise increased retinal VD after rest in emmetropic eyes, and caused significant CT thinning that lasted for at least 30 min in both emmetropic and myopic eyes.

Unilateral Versus Bilateral Refractive Lens Exchange With a Trifocal Intraocular Lens in Emmetropic Presbyopic Patients.

PURPOSE: To compare visual outcomes and patient satisfaction between unilateral and bilateral trifocal diffractive intraocular lens (IOL) implantation in emmetropic patients with presbyopia. DESIGN: Retrospective observational case series. METHODS: This is a multicenter, multisurgeon study of emmetropic presbyopes who underwent refractive lens exchange (RLE) followed by an implantation of FineVision IOL (PhysIOL). Inclusion criteria were emmetropic eyes, with a sphere between -0.25 and +0.50 diopters (D), cylinder of less than 0.75 D and spherical equivalent (SE) between -0.25 and +0.25 D. In addition, uncorrected distance visual acuity (UDVA) had to be Snellen >0.9 in each eye. A total of 171 eyes of 122 patients were evaluated. This sample was divided into 2 groups depending on whether they have been operated monocularly or binocularly. Visual and refractive performance, patient satisfaction, and spectacle independence were evaluated. RESULTS: UDVA and corrected distance visual acuity (CDVA) remained almost unchanged after monocular and binocular surgery. Binocular uncorrected intermediate (UIVA) and near visual acuity (UNVA) were better in those operated binocularly (0.3±0.12 vs 0.22±0.06, P < .063, and 0.09±0.08 vs 0.04±0.05, P < .027, respectively). Predictability and efficacy were higher in the binocular group, whereas safety was better in the monocular group. Visual dysphotopsia was worse and spectacle independence for all distances was higher in binocular group. CONCLUSIONS: Our research shows that RLE with binocular implantation of a trifocal diffractive IOL in presbyopic emmetropic patients is more successful in UNVA than monocular implantation. However, no significant differences were observed in UDVA, UIVA, and patient satisfaction.

Temporal color contrast guides emmetropization in chick.

As a result of longitudinal chromatic aberration (LCA), longer wavelengths are blurred when shorter wavelengths are in focus, and vice versa. As a result, LCA affects the color and temporal aspects of the retinal image with hyperopic defocus. In this experiment, we investigated how the sensitivity to temporal color contrast affects emmetropization. Ten-day-old chicks were exposed for three days to sinusoidal color modulation. The modulation was either blue/yellow flicker (BY) (n = 57) or red/green flicker (RG) (n = 60) simulating hyperopic defocus with and without a blue light component. The color contrasts tested were 0.1, 0.2, 0.3, 0.4, 0.6, and 0.8 Michelson contrast. The mean illuminance of all stimuli was 680 lux. Temporal modulation was either of a high (10 Hz) or low (0.2 Hz) temporal frequency. To test the role of short- and double-cone stimulation, an additional condition silenced these cones in RG_0.4 (D-) and was compared with RG_0.4 (D+) (n = 14). Changes in ocular components and refractive error were measured using Lenstar and a photorefractometer. With high temporal frequency BY representing an in-focus condition for shorter-wavelengths, we found that high temporal frequency BY contrast was positively correlated with vitreous expansion (R2 = 0.87, p < 0.01), expanding the vitreous to compensate for hyperopic defocus. This expansion was offset by low temporal frequency RG, which represented blurred longer wavelengths. The reduction in vitreous expansion in RG_0.4, was enhanced in D+ compared to D- (p < 0.001), indicating a role for short- and/or double-cones. With high temporal frequency RG representing an in-focus condition for longer-wavelengths, we found that high temporal frequency RG contrast was also positively correlated with a linear increase in vitreous chamber depth (R2 = 0.84, p < 0.01) and eye length (R2 = 0.30, p ≤ 0.05), required to compensate for hyperopic defocus, but also with RG sensitive choroidal thickening (R2 = 0.18: p < 0.0001). These increases in the vitreous and eye length were enhanced with D+ compared to D- (p = 0.003) showing the role of short- and double-cones in finessing the vitreous response to hyperopic defocus. Overall, the increase in vitreous chamber depth in RG was offset by reduced expansion in BY, indicating sensitivity to the shorter focal length of blue light and wavelength defocus. Predictable changes in cone contrast and temporal frequency of the retinal image that occur with LCA and defocus result in homeostatic control of emmetropization.

Comparison of refractive value and pupil size under monocular and binocular conditions between the Spot Vision Screener and binocular open-field autorefractor.

We determined the repeatability-reproducibility of refraction values and pupil size measured using the Spot Vision Screener and compare the obtained values with those measured using the binocular open-field autorefractor Grand Seiko WAM 5500 in healthy adults. This cross-sectional study included 22 eyes of 22 healthy adults with emmetropia to myopia. For each participant, spherical equivalent value, cylindrical value, and pupil size were measured in the right eye using the Spot Vision Screener and Grand Seiko autorefractor devices by two different orthoptists under two conditions: monocular and binocular (three consecutive refraction measurements). Repeatability-reproducibility of values measured using both devices were evaluated using intra-class correlation coefficients (ICCs). The mean spherical equivalent value measured using the Spot Vision Screener was -2.79D in the monocular condition and -2.69D in binocular condition, which showed a small significant difference to those measured using the Grand Seiko autorefractor (-2.98D and -2.93D, respectively). The mean cylindrical value measured using the Spot Vision Screener was -0.59D in the monocular condition and -0.52D in the binocular condition, which showed a small significant difference compared with those measured using the Grand Seiko autorefractor in the binocular condition (-0.70D and -0.75D, respectively). Correlation coefficients of the spherical equivalent values, cylindrical values, and pupil sizes measured using both devices were R=0.959 (P<0.001), R=0.243 (P=0.260) and R=0.917 (P<0.001), respectively, in the monocular condition and R=0.962 (P<0.001), R=0.444 (P=0.040), and R=0.832 (P<0.001), respectively, in the binocular condition. ICC values of spherical equivalent value in intra-rater or inter-rater were more than 0.99 in both devices and conditions. ICC values of cylindrical values under the binocular condition in the Spot Vision Screener were 0.636 in intra-rater and 0.574 in inter-rater, which were lower than those of the Grand Seiko autorefractor (0.874 and 0.839, respectively). ICC values of pupil sizes under the binocular condition in the Spot Vision Screener were 0.871 in intra-rater and 0.760 in inter-rater, which were lower than those of the Grand Seiko autorefractor (0.967 and 0.943, respectively). The refractive value and pupil size obtained using the Spot Vision Screener showed high repeatability and reproducibility and were similar to the values obtained using the Grand Seiko autorefractor. Thus, the Spot Vision Screener, an automated vision screener, is a reliable portable refractor and pupillometry device for measuring refractive errors in clinical settings.

Three-dimensional data capture and analysis of intact eye lenses evidences emmetropia-associated changes in epithelial cell organization.

Organ and tissue development are highly coordinated processes; lens growth and functional integration into the eye (emmetropia) is a robust example. An epithelial monolayer covers the anterior hemisphere of the lens, and its organization is the key to lens formation and its optical properties throughout all life stages. To better understand how the epithelium supports lens function, we have developed a novel whole tissue imaging system using conventional confocal light microscopy and a specialized analysis software to produce three-dimensional maps for the epithelium of intact mouse lenses. The open source software package geometrically determines the anterior pole position, the equatorial diameter, and three-dimensional coordinates for each detected cell in the epithelium. The user-friendly cell maps, which retain global lens geometry, allow us to document age-dependent changes in the C57/BL6J mouse lens cell distribution characteristics. We evidence changes in epithelial cell density and distribution in C57/BL6J mice during the establishment of emmetropia between postnatal weeks 4-6. These epithelial changes accompany a previously unknown spheroid to lentoid shape transition of the lens as detected by our analyses. When combined with key findings from previous mouse genetic and cell biological studies, we suggest a cytoskeleton-based mechanism likely underpins these observations.

A role of color vision in emmetropization in C57BL/6J mice.

Spectral composition affects emmetropization in both humans and animal models. Because color vision interacts the effects of chromatic defocus, we developed a method to bypass the effects of longitudinal chromatic aberration by placing a spectral filter behind the optics of the eye, using genetic tools. Newborn C57BL/6J (B6) mice were reared in quasi-monochromatic red (410-510 nm) or blue (585-660 nm) light beginning before eye-opening. Refractive states and ocular dimensions were compared at 4, 6, 8, and 10 weeks with mice reared in normal white light. Cre recombinase-dependent Ai9 reporter mice were crossed with Chx10-Cre to obtain Chx10-Cre;Ai9 mice, expressing red fluorescent protein in retinal Cre-positive cells. Ai9 offsprings, with and without Cre, were reared under a normal visual environment. Refraction and axial components were measured as described above. Expression levels of M and S opsin were quantified by western blotting at 10 weeks. Compared with those reared in white light, B6 mice reared in red light developed relative hyperopia, principally characterized by flattening of corneal curvature. Emmetropization was not affected by blue light, possibly because the reduction in vitreous chamber depth compensated for the increase in corneal curvature. Compared with Cre-negative littermates, the refraction and axial dimensions of Chx10-Cre;Ai9 mice were not significantly different at the follow-up timepoints. M opsin levels were higher in Chx10-Cre;Ai9 mice at 10 weeks while S opsin levels were not different. Red light induced a hyperopic shift in mouse refractive development. Emmetropization was not impacted in mice with perturbed color vision caused by intrinsic red-fluorescent protein, suggesting that color vision may not be necessary in mouse emmetropization when other mechanisms are present.

Resultados del cálculo de la lente intraocular con la fórmula Holladay 2 en pacientes con catarata / Results of intraocular lens calculation with the Holladay 2 formula in cataract patients

RESUMEN Objetivo: Determinar los resultados refractivos en pacientes operados de catarata, según el cálculo del poder dióptrico de la lente intraocular con la fórmula Holladay 2. Métodos: Se realizó un estudio descriptivo prospectivo y longitudinal en 222 ojos de 173 pacientes operados de catarata mediante la técnica de facoemulsificación. Se empleó para el cálculo de la lente el IOL Master 700 y la fórmula Holladay 2. Resultados: Predominó el sexo femenino y el grupo etario mayor de 60 años. En el posoperatorio se observó una mejoría en la agudeza visual sin corrección y corregida de más de 4 líneas en la cartilla de Snellen, independiente de la longitud axial, sin cambios significativos en el cilindro queratométrico. En 69,0 por ciento de los casos el resultado refractivo final estuvo en el rango de la emetropía. Los ojos mayores de 26 mm presentaron una disminución del equivalente esférico superior a 6 dioptrías en el posoperatorio; los menores de 22 mm mostraron la mayor diferencia entre el poder dióptrico de la lente intraocular que se implantó y el que sugiere la fórmula convencional. Conclusiones: La fórmula Holladay 2 resulta útil para el cálculo de la lente intraocular en todos los rangos de longitud axial(AU)

ABSTRACT Objective: Determine refractive results in patients undergoing cataract surgery based on intraocular lens dioptric power calculation with the Holladay 2 formula. Methods: A prospective longitudinal descriptive study was conducted of 222 eyes of 173 patients undergoing cataract surgery by phacoemulsification technique. IOL Master 700 and the Holladay 2 formula were used for lens calculation. Results: There was a predominance of the female sex and the over-60 years age group. The postoperative period was characterized by improvement in visual acuity without correction and corrected of more than 4 lines on the Snellen chart, regardless of axial length, with no significant changes in the keratometric cylinder. In 69.0 percent of the cases, the final refractive result was within the range of emmetropia. Eyes larger than 26 mm displayed a spherical equivalent reduction above 6 diopters postoperative, whereas eyes smaller than 22 mm showed the greatest difference between the dioptric power of the intraocular lens implanted and the one suggested by the conventional formula. Conclusion: The Holladay 2 formula is useful for intraocular lens calculation in all axial length ranges(AU)