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Source publication
We provide an account of the relationships between eye shape, retinal shape and peripheral refraction.
We discuss how eye and retinal shapes may be described as conicoids, and we describe an axis and section reference system for determining shapes. Explanations are given of how patterns of retinal expansion during the development of myopia may...
Citations
... Previous research has explored the morphological changes of the eyeball during the progression of myopia, proposing various models of ocular expansion, including posterior pole, equatorial, global, and axial expansions. [18][19][20] It's worth noting that the influence of visual cues on scleral expansion is remarkably localized. 21 Research in animal models has uncovered that retinal growth exhibits a localized charac-teristic, with distinct regions of the retina independently expanding according to their specific retinal blur signals. ...
Purpose:
To evaluate the refractive differences among school-aged children with macular or peripapillary fundus tessellation (FT) distribution patterns, using fundus tessellation density (FTD) quantified by deep learning (DL) technology.
Methods:
The cross-sectional study included 1942 school children aged six to 15 years, undergoing ocular biometric parameters, cycloplegic refraction, and fundus photography. FTD was quantified for both the macular (6 mm) and peripapillary (4 mm) regions, using DL-based image processing applied to 45° color fundus photographs. Eyes exhibiting tessellation were classified into two groups: the macular distribution group had greater FTD in the macular area, while the peripapillary distribution group had higher FTD in the peripapillary area, allowing for a comparative analysis of axial length (AL), corneal radius, and refraction.
Results:
Participants had a median age of 13 years and a median spherical equivalent (SE) of -0.75 D. The macular distribution group exhibited significantly larger AL (24.13 mm vs. 23.93 mm, P < 0.001) and more myopic refraction (-1.13 D vs. -0.75 D, P < 0.001) compared to the peripapillary group. A higher prevalence of macular-distributed FT was noted in the myopic groups (χ2 = 131.675, P < 0.001). SE negatively correlated with macular (r = -0.238) and peripapillary FTD (r = -0.195), while AL positively correlated with FTD in both regions (r = 0.308; r = 0.265) (all P < 0.001).
Conclusions:
The macular FT distribution pattern is significantly associated with larger AL and greater myopic refraction in school-aged children, suggesting its potential as a marker for identifying children at risk of progressing myopia.
Translational relevance:
DL analysis precisely identifies FT distribution patterns, potentially enhancing early detection of high-risk myopia in populations.
... Ideally, the actual pupil diameter of each individual eye should be considered as this will impact the volume of defocus experienced [35]. Both anterior corneal optics and the retinal shape may contribute to the peripheral refraction and ocular aberrations, and large variations in the retinal shape have been observed among myopes [36]. However, the magnitude of total ocular higher-order aberrations or myopic defocus imposed on the retina were not quantified in the current study, which may limit the ability to predict axial eye growth. ...
Purpose
To explore the associations between myopia defocus dosage (MDD), aberration coefficients (primary spherical aberration and coma), and axial elongation in children undergoing orthokeratology (ortho-k) with back optic zone diameters (BOZD) of 5 mm and 6 mm over 2 years.
Methods
Data from 80 participants from two ortho-k studies were analyzed: 22 and 58 children wore lenses with 5-mm and 6-mm BOZD, respectively. Four MDD metrics were calculated from corneal topography data over a 5-mm pupil for the 1-month and 24-month visits: the circumferential, flat, steep, and volumetric MDD. Corneal primary spherical aberration and comatic aberrations were also extracted from topography data over a 5-mm pupil. Linear mixed modelling was performed to explore the associations between the MDD, corneal aberrations, and axial elongation over 2 years, while controlling for confounding factors (e.g., baseline age and sex).
Results
Participants in the 5-mm BOZD group displayed less axial elongation than the 6-mm BOZD group over 2 years (0.15 ± 0.21 mm vs. 0.35 ± 0.21 mm, P < 0.001). A greater volumetric MDD was observed in the 5-mm BOZD group compared with the 6-mm BOZD group at the 1- and 24-month visits (both P < 0.001). No significant differences were observed between the two groups for the other MDD metrics or corneal aberration coefficients (all P > 0.05). Less axial elongation was associated with a greater volumetric MDD at the 1- and 24-month visits (both β = –0.01, P < 0.001 and P = 0.001), but not with any other MDD metrics or corneal aberrations (all P > 0.05).
Conclusions
The volumetric MDD over a 5-mm pupil after 1 month of ortho-k lens wear was associated with axial elongation after 24 months, and may be a useful predictor of future axial elongation in children undergoing ortho-k.
... A study exploring the effects of age and myopic shift on retinal development revealed that the thickness of the retinal layer in the central recess increased in children (< 10 years) but was unchanged or decreased in adolescents (> 13 years) and that changes in retinal thickness decreased with age 32 . Both the eye optics and the retina's shape affect the retina's peripheral refraction and expansion during myopia development, which also leads to changes in peripheral refraction 33 . Some studies have shown that, as myopia increases, the length of the eyeball grows faster than its height and width; therefore, the eye can change from an oblate/spherical shape to a prolate one 34 . ...
In this population-based observational cross-sectional study, we investigated retinal peripheral refraction in Chinese adults with myopia. We categorized 1511 Chinese adults with myopia (18 − 55 years) into low (LM), moderate (MM), and high myopia (HM) groups. Axial length, central corneal thickness, steep keratometry, flat keratometry, and intraocular pressure were measured. Refractive difference values (RDVs) for different eccentricities (RDV0–53) and the superior (RDV-S), inferior (RDV-I), temporal (RDV-T), and nasal (RDV-N) retinal regions were measured using multispectral refractive topography. The hyperopic defocus was higher for the MM group than for the LM group in RDV20–53, RDV-S, and RDV-T and HM group in RDV20–53, RDV-S, RDV-T and RDV-N. The hyperopic defocus was higher for the HM group than for the LM group in RDV20-53, RDV-S and RDV-T but lower for the LM group in RDV-N. RDV-N decreased with age (R² = 0.0191, slope = − 0.01, p < 0.0001), whereas RDV-S (R² = 0.0112, slope = 0.01,p < 0.0001) and RDV-T increased (R² = 0.0038, slope = 0.01, p = 0.0160). RDV correlated with central spherical equivalent and axial length. Flat keratometry explained the most RDV variation (RDV20–30: β = 0.0714, p < 0.0001; RDV-N: β = 0.1801, p < 0.0001; RDV-S: β = 0.1426, p < 0.0001; RDV-T: β = 0.1239, p < 0.0001). Reference values for peripheral retinal defocus are provided for Chinese adults with different myopia ranges.
... It acquires even more importance for subjects with pathologies that hinder central vision [3] for whom peripheral aberration correction can improve their quality of life [4]. Despite this, the study of peripheral optics was not a very hot research topic until its potential link to myopia progression was proposed [5][6][7][8]. Due to the high prevalence of myopia [9] and its relationship with several blind-threatening diseases [10], there is great interest in the mechanisms underlying its progression and prevention. ...
... However, the role of peripheral refraction as a risk predictor for myopia and high myopia is still a matter of debate. While earlier studies in humans have presented the relationship between relative peripheral hyperopia and myopia development [16,17] as a promising predictive tool, more recent studies focused on the horizontal field have concluded that this trend could be a consequence rather than a cause of myopia [5,18,19]. The situation may be different for the vertical meridian, as ocular size and peripheral refraction have been found to change differently in the horizontal and vertical dimensions depending on central refraction [20,21]. ...
... To this end, we performed a fit to a second-order ellipsoidal function of UPER retinal maps in a smaller inner region (angles at or closer than 25°to fovea). This shape was chosen as it has been shown to accurately describe larger sections of the retina [5]. ...
We compared the peripheral refractive measurements of a recently proposed laser-scanning instrument with an established peripheral refractor. Two-dimensional refractive maps were obtained using both instruments for 18 young subjects with differing values of central refraction. The comparison shows a strong correlation between devices in the overlapping measurement area, with the new device extending the range of the explored retinal area to a 100-degree-diameter circular patch, compared to the 60°x35° rectangular area of the older peripheral refractor. Larger refractive maps exhibit trends that cannot be easily predicted from narrower scans. These results demonstrate that the new instrument can be a useful tool for assessing wide-angle peripheral optical data in the human eye.
... This difference is likely be due to groups' differences in globe shape which affects relative peripheral defocus. For example, myopes' axial elongation is coincident with a prolate globe shape and relative peripheral hyperopia [50][51][52], whereas hyperopia is associated with a more oblate globe shape and relative peripheral myopia. ...
Detecting optical defocus at the retina is crucial for accurate accommodation and emmetropization. However, the optical characteristics of ocular defocus are not fully understood. To bridge this knowledge gap, we simulated polychromatic retinal image quality by considering both the monochromatic wavefront aberrations and chromatic aberrations of the eye, both in the fovea and the periphery (nasal visual field). Our study revealed two main findings: (1) chromatic and monochromatic aberrations interact to provide a signal to the retina (chromatic optical anisotropy) to discern positive from negative defocus and (2) that chromatic optical anisotropy exhibited notable differences among refractive error groups (myopes, emmetropes and hyperopes). These findings could enhance our understanding of the underlying mechanisms of defocus detection and their subsequent implications for myopia control therapies. Further research is needed to explore the retinal architecture’s ability to utilize the optical signals identified in this study.
... As myopia progresses, myopic children's eyes elongate and become less oblate, with the axial dimension growing the most, followed by the vertical and horizontal dimensions, in a ratio of approximately 3:2:1 [27]. RPR changes may indirectly describe retinal shape and reflect different patterns of eye growth [28]. The 1/7 group elongated the most and displayed less oblateness in retinal morphology, while the 7/7 and 2/7 groups tended towards oblateness in the retina. ...
Background
Atropine, specifically 0.05% eyedrops, has proven effective in slowing myopia progression. This study aims to investigate peripheral refraction (PR) characteristics in myopic children treated with 0.05% atropine eyedrops at different frequencies.
Methods
One hundred thirty-eight myopic children completed this one-year prospective study, randomly assigned to once daily (7/7), twice per week (2/7), or once per week (1/7) groups. Spherical equivalent (SE) and axial length (AL) were measured. PR was assessed using a custom-made Hartmann-Shack wavefront peripheral sensor, covering a visual field of horizontal 60° and vertical 36°. Relative peripheral refraction (RPR) was calculated by subtracting central from peripheral measurements.
Results
After one year, SE increased more significantly in the 1/7 group compared to the 7/7 group ( P < 0.001) and 2/7 group ( P = 0.004); AL elongation was also greater in the 1/7 group compared to the 7/7 group ( P < 0.001). In comparison with higher frequency groups, 1/7 group exhibited more myopic PR in the fovea and its vertical superior, inferior, and nasal retina; and less myopic RPR in the periphery retina after one-year ( P < 0.05). Additionally, RPR in the 7/7 group demonstrated myopic shift across the entire retina, the 2/7 group in temporal and inferior retina, while the 1/7 group showed a hyperopic shift in the superior retina ( P < 0.05). Moreover, myopic shift of RPR in the temporal retina is related to less myopia progression, notably in the 7/7 group ( P < 0.05).
Conclusions
Atropine inhibits myopia progression in a frequency-dependent manner. The once-daily group showed the slowest myopia progression but exhibited more myopic shifts in RPR. Additionally, RPR in the temporal retina was related to myopia progression in all groups.
Trial registration
Chinese Clinical Trial Registry, ChiCTR2100043506. Registered 21 February 2021, https://www.chictr.org.cn/showproj.html?proj=122214
... The terms oblate and prolate refer to ellipses that steepen and flatten, respectively, away from their vertices, which in this context approximately corresponds to the line of sight. 12 For wider angles, the posterior globe is generally oblate for most emmetropic and myopic eyes, but this tends to reduce for larger amounts of myopia. 13,14 It is likely that optical coherence tomography and its algorithms will develop to improve the determination of the retinal shape at relatively central regions, corresponding to the range of angles over which peripheral refraction is usually measured. ...
... Although the elongation of the eyeball in HM leads to the thinning of many ocular structures, such as posterior sclera, choroid and retina, as previously described [33,34], our results in HMG with an AXL range from 26.0 mm to 33.7 mm indicate insignificant correlation between AST measurements and AXL, ACD and ACA (p > 0.05). In accordance, Li et al. [11], in their study of high myopic eyes (26.68 ± 0.96), found no significant correlation (p > 0.05) between AXL and AST0,1,2,3. ...
Background: To assess the anterior scleral thickness (AST), Schlemm’s canal diameter (SCD), trabecular meshwork diameter (TMD) and conjunctiva tenon capsule thickness (CTT) in high myopic (HM) subjects and HM subjects with glaucoma (HMG) compared to control eyes. Methods: One hundred and twenty eyes were included, and AST at 0, 1, 2 and 3 mm from the scleral spur, SCD, TMD and CTT were measured. Results: Mean age was 64.2 ± 11.0 years, and the temporal SCD and temporal TMD were significantly longer in the HMG subjects compared to the controls (380.0 ± 62 μm vs. 316.7 ± 72 μm, p = 0.001) and (637.6 ± 113 μm vs. 512.1 ± 97 μm, p = 0.000), respectively. There were no significant differences between the HM and HMG subjects in SCD and TMD (all p > 0.025). Compared to the HM subjects, the temporal AST0 (432.5 ± 79 μm vs. 532.8 ± 99 μm, p = 0.000), temporal AST1 (383.9 ± 64 μm vs. 460.5 ± 80 μm, p = 0.000), temporal AST2 (404.0 ± 68 μm vs. 464.0 ± 88 μm, p = 0.006) and temporal AST3 (403.0 ± 80 μm vs. 458.1 ± 91 μm, p = 0.014) were significantly thinner in the HMG group. No differences were found between the CTT in the three groups (all p > 0.025). Conclusions: Our data indicate a thinner AST in HMG subjects and no differences in SCD and TMD between HM and HMG subjects.
... 6 Peripheral defocus refers to the myopia degree state of the peripheral retina; the optics of the eyeball and the curve of the retina both contribute to the peripheral refraction of the retina. 15 Defocus of the peripheral retina has benefits in controlling the growth in axial length, which may be associated with reducing changes in choroidal thickness. 16 A previous study indicated that the defocused signals around the retina occupy a dominant position in the process of growth in axial length. ...
Objective
To investigate the association between the peripheral refractive errors of the fundus in different regions and moderate and high myopia.
Methods
In this case-control study, 320 children and adolescents aged 6 to 18 years were recruited. Peripheral refractive errors were measured using multispectral retinal refractive topography (MRT). Spherical equivalent (SE) and cylinder errors were classified into low, moderate, and high categories based on the magnitude range. Logistic regression was performed to test the factors associated with myopia.
Results
There were 152 participants with low myopia and 168 participants with moderate and high myopia included in the current study. Participants with moderate and high myopia were most likely to be older, with larger axial length (AL), lower SE, less time to watch electronic devices on the weekend, a higher difference between central refractive error and paracentral refractive error from the superior side of the retina (RDV-S), but a smaller difference between the central refractive error and paracentral refractive error from the inferior side of the retina (RDV-I) than those with low myopia (all P <0.05). After logistic analysis, female sex (odds ratio [OR] = 4.14; 95% confidence interval [CI] = 2.16–7.97, P <0.001), AL (OR = 6.88, 95% CI = 4.33–10.93, P <0.001), and RDV-I (OR = 0.52, 95% CI = 0.32–0.86, P = 0.010) were independent factors for moderate and high myopia.
Conclusion
Our study demonstrated that the retina peripheral refraction of the eyes (RDV-I) was associated with moderate and high myopia, and RDV-S was only associated with high myopia.
... Extrapolating these findings to the broader context of ocular morphology, it is important to note that various factors can contribute to the shape of the eye, which would be influenced by alterations in the anatomical structures of the eye, including the cornea, lens, retina, and sclera [24,25]. In this study, the result of eyeball enlargement was obtained by measuring the volume of the entire eyeball surface. ...
Strabismus, a neuro-ophthalmological condition characterized by misalignment of the eyes, is a common ophthalmic disorder affecting both children and adults. In our previous study, we identified the microsomal glutathione S-transferase 2 (MGST2) gene as one of the potential candidates for comitant strabismus susceptibility in a Japanese population. The MGST2 gene belongs to the membrane-associated protein involved in the generation of pro-inflammatory mediators, and it is also found in the protection against oxidative stress by decreasing the reactivity of oxidized lipids. To look for the roles of the MGST2 gene in the development, eye alignment, and overall morphology of the eye as the possible background of strabismus, MGST2 gene knockout (KO) mice were generated by CRISPR/Cas9-mediated gene editing with guide RNAs targeting the MGST2 exon 2. The ocular morphology of the KO mice was analyzed through high-resolution images obtained by a magnetic resonance imaging (MRI) machine for small animals. The morphometric analyses showed that the height, width, and volume of the eyeballs in MGST2 KO homozygous mice were significantly greater than those of wild-type mice, indicating that the eyes of MGST2 KO homozygous mice were significantly enlarged. There were no significant differences in the axis length and axis angle. These morphological changes may potentially contribute to the development of a subgroup of strabismus.
