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Mrs. Mole, I'm home!
When Morris Mole loses his glasses, he decides to try to find his way home from work without them, but he soon finds that he didn't know his way as well as he had thought.
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Defocus Incorporated Multiple Segments (DIMS) spectacle lenses slow myopia progression: a 2-year randomised clinical trial
AimTo determine if ‘Defocus Incorporated Multiple Segments’ (DIMS) spectacle lenses slow childhood myopia progression.MethodsA 2-year double-masked randomised controlled trial was carried out in 183 Chinese children aged 8–13 years, with myopia between −1.00 and −5.00 D and astigmatism ≤1.50 D. Children were randomly assigned to wear DIMS (n=93) or single vision (SV) spectacle lenses (n=90). DIMS lens incorporated multiple segments with myopic defocus of +3.50 D. Refractive error (cycloplegic autorefraction) and axial length were measured at 6month intervals.Results160 children completed the study, n=79 in the DIMS group and n=81 in the SV group. Average (SE) myopic progressions over 2 years were −0.41±0.06 D in the DIMS group and −0.85±0.08 D in the SV group. Mean (SE) axial elongation was 0.21±0.02 mm and 0.55±0.02 mm in the DIMS and SV groups, respectively. Myopia progressed 52% more slowly for children in the DIMS group compared with those in the SV group (mean difference −0.44±0.09 D, 95% CI −0.73 to −0.37, p<0.0001). Likewise, children in the DIMS group had less axial elongation by 62% than those in the SV group (mean difference 0.34±0.04 mm, 95% CI 0.22 to 0.37, p<0.0001). 21.5% children who wore DIMS lenses had no myopia progression over 2 years, but only 7.4% for those who wore SV lenses.ConclusionsDaily wear of the DIMS lens significantly retarded myopia progression and axial elongation in myopic children. Our results demonstrated simultaneous clear vision with constant myopic defocus can slow myopia progression.Trial registration number NCT02206217.
Journal Article
The correlation between myopia severity and stress–strain index (SSI) using the Corneal Visualization Scheimpflug Technology (Corvis ST)
This study aimed to investigate the correlation between myopia severity and the stress–strain index (SSI), measured with the Corneal Visualization Scheimpflug Technology (Corvis ST) device. The subjects were divided into two groups, based on both the axial length (AL) and spherical equivalent refraction (SER): 22–26.00 AL group (22 mm < AL < 26.00 mm) associated with SER of less than − 6.00D, and ≥ 26.00 AL group (AL ≥ 26.00 mm) associated with SER over − 6.00D. The differences in the Corvis ST-derived dynamic corneal response parameters and stiffness parameters between the two groups were investigated. The correlation between SSI and AL, SER, age, ratio of AL to radius of corneal curvature (CR) (AL/CR), and axial length minus anterior chamber depth (ACD) (AL-ACD) were analyzed. The SSI (0.95 ± 0.13 in the 22–26.00 AL group and 0.86 ± 0.15 in the ≥ 26.00 AL group) were significantly different between the two groups (
P
< 0.01). In the ≥ 26.00 AL group, there was evidence of a weak negative correlation between SSI and AL (r = − 0.265,
P
< 0.01), AL/CR (r = − 0.376,
P
< 0.01), and AL-ACD (r = − 0.224,
P
< 0.01); and a weak positive correlation between SSI and SER (r = 0.251,
P
< 0.01). However, in the 22–26.00 AL group, there was no correlation between SSI and AL, AL-ACD, AL/CR or SER (
P
> 0.05). SSI was significantly correlated with AL, which is the major determinant of SER, in the ≥ 26.00 AL group. This correlation was not affected with CR and ACD, as both AL/CR and AL-ACD also correlated with SSI at the same degree.
Journal Article
Long-term visual quality after small incision lenticule extraction for low myopia
Few studies have reported the visual outcomes of small-incision lenticule extraction (SMILE) and laser-assisted subepithelial keratomileusis (LASEK) for myopia correction. This study aims to compare the visual quality and corneal wavefront aberrations after SMILE and LASEK for low-myopia correction. In this prospective study, we included 29 eyes of 29 patients who received SMILE and 23 eyes of 23 patients who received LASEK between June 2018 and January 2019. The following measurements were assessed: uncorrected (UDVA) and corrected (CDVA) distance visual acuity, manifest refraction, corneal wavefront aberrations, and subjective visual quality. All patients were followed up for two years. All procedures were uneventful. An efficacy index of 1.19 [+ or -] 0.17 was established in the SMILE group and 1.23 [+ or -] 0.20 in the LASEK group. No eyes lost more than two lines of CDVA. We found that 93% (27/29) of the treated eyes in the SMILE group and 91% (21/23) in the LASEK group had spherical equivalent (SE) within [+ or -] 0.25D. The increases in the total corneal spherical aberration and the corneal front spherical aberration were lower in the SMILE group than in the LASEK group (P < 0.01). In contrast, the increases in the total corneal vertical coma and the corneal front vertical coma in the SMILE group were greater than those in the LASEK group (P < 0.01). Both SMILE and LASEK have good safety, stability, and patient-reported satisfaction for low myopia. SMILE induced less corneal spherical aberration but greater vertical coma than LASEK.
Journal Article
A Comprehensive Review of Myopia
Myopia is a prevalent refractive error affecting millions worldwide, with a significant increase in incidence expected in the coming years, particularly in areas experiencing rapid urbanization. Uncorrected myopia as low as -1.50 diopters is considered to cause moderate visual impairment, and regular monitoring by healthcare professionals is crucial for effective management. High myopia poses a greater risk for sight-threatening complications such as myopic maculopathy, glaucoma, and cataracts. The onset and progression of myopia are influenced by both genetic and environmental factors, with the latter playing a more prominent role. Significant efforts have been made to slow myopia progression through optical, environmental, and pharmaceutical interventions. Genes involved in circadian rhythm regulation, pigmentation, and collagen metabolism have been associated with myopia development. Environmental factors such as near work, lack of outdoor activity, improper lighting, and socioeconomic conditions contribute to the rising prevalence of myopia. Optical approaches for myopia control include bifocals, progressive addition spectacles, and contact lenses incorporating peripheral defocus management. Pharmaceutical strategies explored include atropine, pirenzepine, tropicamide, 7-methylxanthine, and certain intraocular pressure-lowering agents. Long-term efficacy data for these interventions are limited, and concerns exist regarding the potential rebound effect upon treatment discontinuation. A multifaceted approach addressing both genetic predisposition and environmental modifications is necessary to control the growing global burden of myopia effectively.
Journal Article
Effect of low-dose atropine on myopia progression, pupil diameter and accommodative amplitude: low-dose atropine and myopia progression
PurposeTo evaluate the effects of 0.01% and 0.02% atropine eye drops on myopia progression, pupil diameter and accommodative amplitude in myopic children.MethodsA cohort study assessed 400 myopic children divided into three groups: 138 and 142 children were randomised to use either 0.02% or 0.01% atropine eye drops, respectively. They wore single-vision (SV) spectacles, with one drop of atropine eye drop applied to both eyes once nightly. Control children (n=120) only wore SV spectacles. Repeated measurements of spherical equivalent refractive errors (SERs), axial length (AL), pupil diameter and accommodative amplitude were performed at baseline, and 4, 8 and 12 months after treatment.ResultsAfter 12 months, the SER change was −0.38±0.35D, −0.47±0.45D, −0.70±0.60D and AL change was 0.30±0.21 mm, 0.37±0.22 mm, 0.46±0.35 mm in the 0.02%, 0.01% atropine and control groups, respectively. There were significant differences in the change in AL and SER between three groups (all p<0.001). Between baseline and the 12-month visit, the overall change in accommodative amplitude was 1.50±0.25D, 1.61±0.31D and change in pupil diameter was 0.78±0.42 mm, 0.69±0.39 mm, with 0.02% and 0.01% atropine, respectively. Accommodative amplitude significantly decreased and pupil diameter significantly increased in two atropine groups (all p<0.001). Moreover, there was no statistical difference in the change difference in accommodative amplitude and pupil diameter between two atropine groups (p=0.24, p=0.38), whereas the accommodative amplitude (p=0.45) and pupil diameter (p=0.39) in the control group remained stable.Conclusions0.02% atropine eye drops had a better effect on myopia progression than 0.01% atropine, but 0.02% and 0.01% atropine showed similar effects on pupil diameter and accommodative amplitude after 12 months of treatment.Trial registration numberChiCTR-IPD-16008844.
Journal Article
Transepithelial Versus Epithelium-off Photorefractive Keratectomy in High Compound Myopic Astigmatism: A Contralateral Eye Study
Purpose
To compare clinical outcomes of transepithelial photorefractive keratectomy (t-PRK) and conventional epithelium-off PRK (PRK) in patients with high compound myopic astigmatism.
Methods
Sixty eyes of 30 myopic individuals with at least −2.50 diopters (D) of spherical equivalent and 3.00 D of cylindrical refractive error were enrolled in the study. Both eyes of each patient were randomly assigned to either the t-PRK method or epithelium-off PRK as a matched contralateral control group. Refractive outcomes were evaluated 6 months after surgery.
Results
At the 6-month visit, cylindrical refractive error magnitude was lower in the t-PRK (0.51 ± 0.29 D) compared to the PRK (0.67 ± 0.30 D) group (P = .04). The residual astigmatism was 0.50 diopters or less in 23 eyes (76%) in the t-PRK group and 15 eyes (50%) in the PRK group. In vector analysis using the Alpins method, t-PRK resulted in a significantly higher percentage of success of astigmatic surgery (84.68 ± 8.95 in t-PRK versus 79.46 ± 10.88 in PRK, P = .04). Additionally, there was a marginal advantage for the t-PRK group regarding index of success of astigmatism surgery (P = .06) and absolute (P = .08) and arithmetic (P = .07) angles of error compared to the PRK group. Both groups had an equal safety profile.
Conclusions
T-PRK is more accurate for astigmatic correction in high astigmatism than conventional PRK. Both t-PRK and PRK are comparable respecting safety and efficacy.
[J Refract Surg. 2024;40(12):e956–e965.]
Journal Article
Comparison of changes in corneal volume and corneal thickness after myopia correction between LASIK and SMILE
Myopia is the most common refractive error. Surgical correction with laser is possible. LASIK and SMILE are the techniques currently most used. Aim of the study was to compare changes in corneal volume and thickness after the respective laser treatment. 104 eyes of 52 patients were matched based on refractive error into two equally sized groups, either treated with LASIK or SMILE. Measurements were obtained from the Scheimpflug camera (Pentacam) preoperatively and at 3 and 12 months postoperatively. 3 months postoperatively, the flapless SMILE procedure resulted in a significant overall greater loss of corneal volume (P < 0.01) and corneal thickness (P < 0.01) compared to LASIK. No significant difference was found when comparing the 3 to 12-months values in each group. Within the currently used ranges of refractive error correction, loss in central corneal thickness and corneal volume with SMILE is higher in comparison to LASIK. As greater loss in corneal volume and thickness might contribute to higher level of corneal instability maximum ranges of refractive error correction with SMILE should not supersede those set currently for LASIK until more long-term results on corneal ectasia are available for SMILE.
Journal Article
Low-dose (0.01%) atropine eye-drops to reduce progression of myopia in children: a multicentre placebo-controlled randomised trial in the UK (CHAMP-UK)—study protocol
Background/aimsTo report the protocol of a trial designed to evaluate the efficacy, safety and mechanism of action of low-dose atropine (0.01%) eye-drops for reducing progression of myopia in UK children.MethodsMulticentre, double-masked, superiority, placebo-controlled, randomised trial. We will enrol children aged 6–12 years with myopia of −0.50 dioptres or worse in both eyes.We will recruit 289 participants with an allocation ratio of 2:1 (193 atropine; 96 placebo) from five centres. Participants will instil one drop in each eye every day for 2 years and attend a research centre every 6 months. The vehicle and preservative will be the same in both study arms.The primary outcome is SER of both eyes measured by autorefractor under cycloplegia at 2 years (adjusted for baseline). Secondary outcomes include axial length, best corrected distance visual acuity, near visual acuity, reading speed, pupil diameter, accommodation, adverse event rates and allergic reactions, quality of life (EQ-5D-Y) and tolerability at 2 years. Mechanistic evaluations will include: peripheral axial length, peripheral retinal defocus, anterior chamber depth, iris colour, height and weight, activities questionnaire, ciliary body biometry and chorioretinal thickness. Endpoints from both eyes will be pooled in combined analysis using generalised estimating equations to allow for the correlation between eyes within participant. Three years after cessation of treatment, we will also evaluate refractive error and adverse events.ConclusionsThe Childhood Atropine for Myopia Progression in the UK study will be the first randomised trial reporting outcomes of low-dose atropine eye-drops for children with myopia in a UK population.Trial registration number ISRCTN99883695, NCT03690089.
Journal Article
Optical Defocus Rapidly Changes Choroidal Thickness in Schoolchildren
The current study aimed to examine the short-term choroidal response to optical defocus in schoolchildren. Myopic schoolchildren aged 8-16 were randomly allocated to control group (CG), myopic defocus group (MDG) and hyperopic defocus group (HDG) (n = 17 per group). Children in MDG and HDG received additional +3D and -3D lenses, respectively, to their full corrections on the right eyes. Full correction was given to their left eyes, and on both eyes in the CG. Axial length (AXL) and subfoveal choroidal thickness (SFChT) were then measured by spectral domain optical coherence tomography. Children wore their group-specific correction for 2 hours after which any existing optical defocus was removed, and subjects wore full corrections for another 2 hours. Both the AXL and SFChT were recorded hourly for 4 hours. The mean refraction of all subjects was -3.41 ± 0.37D (± SEM). SFChT thinned when exposed to hyperopic defocus for 2 hours but less thinning was observed in response to myopic defocus compared to the control group (p < 0.05, two-way ANOVA). Removal of optical defocus significantly decreased SFChT in the MDG and significantly increased SFChT in the HDG after 1 and 2 hours (mean percentage change at 2-hour; control vs. hyperopic defocus vs. myopic defocus; -0.33 ± 0.59% vs. 3.04 ± 0.60% vs. -1.34 ± 0.74%, p < 0.01). Our results showed short-term exposure to myopic defocus induced relative choroidal thickening while hyperopic defocus led to choroidal thinning in children. This rapid and reversible choroidal response may be an important clinical parameter in gauging retinal response to optical defocus in human myopia.
Journal Article