“…Normally, the lenslets should be located in the periphery, and central vision should be aligned with the central clear zone. Studies have found that VA was not affected when looking through the central clear zone ( Lam et al, 2019 ; Zhang et al, 2020 ).…”
Section: Discussionmentioning
confidence: 99%
“…The geometry of the aspheric lenslets (1.12 mm in diameter) was calculated to generate a volume of myopic defocus ranging from 1.1 to 1.9 mm (HAL) and from 1.0 to 1.3 mm (SAL) in front of the retina at any eccentricity, serving as a myopia control signal. The lenslets (1.03 mm in diameter) of HC introduce myopic defocus at a plane in front of the retina by a relative positive power (+3.50 D) ( Lu et al, 2020 ; Zhang et al, 2020 ). The surface of the lens without lenslets provides distance correction.…”
Purpose: This study aimed to evaluate short-term visual performance and optical quality of three different lenslet configurations on myopia control spectacle lenses.Materials and Methods: This study utilized a cross-over design. Distance visual acuity (VA) was measured in 50 myopic children; contrast sensitivity (CS) was measured in 36 myopic children. For each test, four spectacle lenses were evaluated in a random order: single-vision lens (SVL), lens with concentric rings of highly aspherical lenslets (HAL), lens with concentric rings of slightly aspherical lenslets (SAL), and lens with honeycomb configuration of spherical lenslets (HC). The modulation transfer function (MTF) and MTF area (MTFa) were used to determine optical quality. All tests were performed monocularly on the right eye with full correction.Results: HAL and SAL had larger MTFa than HC. VA in lenses with lenslets was significantly reduced compared to SVL (all p < 0.01). The reduction in VA was worse with HC than with SAL (p = 0.02) and HAL (p = 0.03); no effect of lenslet asphericity was found (p > 0.05). VA changes induced by lenslets showed no correlation with spherical equivalent refraction (all p > 0.05) and were weakly positively associated with age for SAL (r = 0.36, p = 0.01) and HC (r = 0.31, p = 0.03), but not for HAL (p = 0.30). The area under the log contrast sensitivity function (AULCSF) decreased with HAL and HC (all p < 0.001) in all illumination levels, and AULCSF with HAL was higher than that with HC in a photopic condition (1.17 ± 0.10 vs. 1.10 ± 0.13, p = 0.0004). The presence of lenslets did not affect CS at 3 cycles per degree (cpd) (p = 0.80). At 6 to 18 cpd, CS was significantly reduced by HAL and HC (all p < 0.05), but not SAL (p > 0.05) compared to SVL. At high spatial frequencies (>12 cpd) both SAL and HAL reduced CS significantly less than HC (all p < 0.01).Conclusion: Short-term visual performance was minimally impaired by looking through the lenslet structure of myopia control spectacle lenses. Concentric rings with aspherical lenslets had a significantly lower impact on both VA and CS than honeycomb configuration with spherical lenslets.
“…Normally, the lenslets should be located in the periphery, and central vision should be aligned with the central clear zone. Studies have found that VA was not affected when looking through the central clear zone ( Lam et al, 2019 ; Zhang et al, 2020 ).…”
Section: Discussionmentioning
confidence: 99%
“…The geometry of the aspheric lenslets (1.12 mm in diameter) was calculated to generate a volume of myopic defocus ranging from 1.1 to 1.9 mm (HAL) and from 1.0 to 1.3 mm (SAL) in front of the retina at any eccentricity, serving as a myopia control signal. The lenslets (1.03 mm in diameter) of HC introduce myopic defocus at a plane in front of the retina by a relative positive power (+3.50 D) ( Lu et al, 2020 ; Zhang et al, 2020 ). The surface of the lens without lenslets provides distance correction.…”
Purpose: This study aimed to evaluate short-term visual performance and optical quality of three different lenslet configurations on myopia control spectacle lenses.Materials and Methods: This study utilized a cross-over design. Distance visual acuity (VA) was measured in 50 myopic children; contrast sensitivity (CS) was measured in 36 myopic children. For each test, four spectacle lenses were evaluated in a random order: single-vision lens (SVL), lens with concentric rings of highly aspherical lenslets (HAL), lens with concentric rings of slightly aspherical lenslets (SAL), and lens with honeycomb configuration of spherical lenslets (HC). The modulation transfer function (MTF) and MTF area (MTFa) were used to determine optical quality. All tests were performed monocularly on the right eye with full correction.Results: HAL and SAL had larger MTFa than HC. VA in lenses with lenslets was significantly reduced compared to SVL (all p < 0.01). The reduction in VA was worse with HC than with SAL (p = 0.02) and HAL (p = 0.03); no effect of lenslet asphericity was found (p > 0.05). VA changes induced by lenslets showed no correlation with spherical equivalent refraction (all p > 0.05) and were weakly positively associated with age for SAL (r = 0.36, p = 0.01) and HC (r = 0.31, p = 0.03), but not for HAL (p = 0.30). The area under the log contrast sensitivity function (AULCSF) decreased with HAL and HC (all p < 0.001) in all illumination levels, and AULCSF with HAL was higher than that with HC in a photopic condition (1.17 ± 0.10 vs. 1.10 ± 0.13, p = 0.0004). The presence of lenslets did not affect CS at 3 cycles per degree (cpd) (p = 0.80). At 6 to 18 cpd, CS was significantly reduced by HAL and HC (all p < 0.05), but not SAL (p > 0.05) compared to SVL. At high spatial frequencies (>12 cpd) both SAL and HAL reduced CS significantly less than HC (all p < 0.01).Conclusion: Short-term visual performance was minimally impaired by looking through the lenslet structure of myopia control spectacle lenses. Concentric rings with aspherical lenslets had a significantly lower impact on both VA and CS than honeycomb configuration with spherical lenslets.
“…This theory of the progression of myopia suggests that axial elongation is driven by peripheral retinal hyperopic defocus; in this sense, any hyperopic blur in the peripheral retina has been shown to conduct to axial length and myopia progression in animal and human studies. On the basis of this theory it has been considered that minimising the retinal peripheral hyperopic defocus or inducing peripheral myopic defocus with bifocal progressive addition spectacles (PAL), peripheral defocus ophthalmic lens [ 29 ] or with different designs of CLs could prevent myopic progression [ 19 ]. The mechanisms that support myopia control with CLs are also based on the change in retinal peripheral defocus [ 22 ].…”
Section: Current Treatment Options and Gapsmentioning
Myopia has become a major public health problem in the world due to the increase in its prevalence in the past few decades and due to sight-threatening pathologies associated with high myopia such as cataracts, glaucoma and especially myopic maculopathy. This article is a narrative review of the evidence that currently exists on a contact lenses (CLs) specifically designed to correct myopia and to slow its progression. To contextualise the topic we discuss the different classifications and definitions that have been used for myopia, the current burden of being myopic, and current treatment options to prevent and control its progression. There is evidence that exposure to sunlight reduces the risk of myopia onset and pharmacological treatment with atropine has been shown to be the most effective therapy for controlling its progression, followed by optical interventions such as CL fitting (orthokeratology or CLs specific for myopia control) designed to decrease retinal peripheral hyperopic defocus that seems to be the theory that suggests that axial elongation is driven by this defocus and explains why the eye continues to grow abnormally after emmetropisation and generates myopia. We will especially focus on MiSight CLs. MiSight is a daily replacement soft contact lens that has been clinically proven and approved by the US Food and Drug Administration (FDA) to control the progression of myopia in children. We analyse the optical design of MiSight CLs, as well as the results of the different efficacy and safety studies that led to the approval of the lens by the FDA. We also expose current knowledge gaps, limitations and future directions.
“…For patients with poor compliance with follow-up visits, there is no reason to believe that they can use antibiotics correctly when indicated and, considering the potential risk arising from non-compliance with treatment, they are probably not suitable candidates for ortho-k treatment. Currently, there are several novel non-contact lens myopia control modalities other than ortho-k, including specially designed spectacles [ 15 , 16 ] and low-concentration atropine [ 17 , 18 ], which could be considered when compliance is an issue for patients.…”
It has been previously reported that the improper prescribing of antibiotic eye drops is common among orthokeratology (ortho-k) practitioners. Guidelines have since been developed and disseminated to improve their understanding and implementation of antibiotic prescriptions. This study aimed to investigate the influence of these guidelines on the knowledge, attitude, and prescribing habits of ortho-k practitioners by means of a questionnaire, which was administered nationwide via an official online account to eye care practitioners (ECPs) involved in ortho-k lens fitting, 548 of whom completed the survey. Differences in characteristics before and after the dissemination of the guidelines and between the groups were explored using χ2 tests. The relationship between prescribing habits and demographics was analyzed using stepwise logistic regression models. The implementation of the guidelines significantly improved the overall prescribing habits of ECPs (p < 0.001), especially for prophylactic antibiotic use before and after ortho-k lens wear (p < 0.001). Most ECPs who prescribed antibiotics properly displayed significantly better knowledge of correct antibiotic use, which in turn affected the compliance in their ortho-k patients (p < 0.001). The ECPs’ occupations (professionals other than ophthalmologists and optometrists, including nurses and opticians), clinical setting (distributor fitting centers), and age (younger than 25 years) were risk factors for the misuse of antibiotics. Although the implementation of the antibiotic guidelines significantly improved overall prescribing habits, some practitioners’ prescribing behavior still needs improvement. A limitation of this study was that all questions were mandatory, requiring ECPs to recall information, and therefore was subjected to selection and recall bias.
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