The Effect of Fractal Contact Lenses on Peripheral Refraction in Myopic Model Eyes

Purpose: To test multizone contact lenses in model eyes: Fractal Contact Lenses (FCLs), designed to induce myopic peripheral refractive error (PRE). Methods: Zemax ray-tracing software was employed to simulate myopic and accommodation-dependent model eyes fitted with FCLs. PRE, defined in terms of mean sphere M and 90–180 astigmatism J180, was computed at different peripheral positions, ranging from 0 to 35 in steps of 5, and for different pupil diameters (PDs). Simulated visual performance and changes in the PRE were also analyzed for contact lens decentration and model eye accommodation. For comparison purposes, the same simulations were performed with another commercially available contact lens designed for the same intended use: the Dual Focus (DF). Results: PRE was greater with FCL than with DF when both designs were tested for a 3.5 mm PD, and with and without decentration of the lenses. However, PRE depended on PD with both multizone lenses, with a remarkable reduction of the myopic relative effect for a PD of 5.5 mm. The myopic PRE with contact lenses decreased as the myopic refractive error increased, but this could be compensated by increasing the power of treatment zones. A peripheral myopic shift was also induced by the FCLs in the accommodated model eye. In regard to visual performance, a myopia under-correction with reference to the circle of least confusion was obtained in all cases for a 5.5 mm PD. The ghost images, generated by treatment zones of FCL, were dimmer than the ones produced with DF lens of the same power. Conclusions: FCLs produce a peripheral myopic defocus without compromising central vision in photopic conditions. FCLs have several design parameters that can be varied to obtain optimum results: lens diameter, number of zones, addition and asphericity; resulting in a very promising customized lens for the treatment of myopia progression.This research was supported by the Ministerio de Economia y Competitividad (grant FIS2011-23175), the Generalitat Valenciana (grant PROMETEO2009-077) and the Universitat Politecnica de Valencia (grant INNOVA SP20120569), Spain.Rodríguez Vallejo, M.; Benlloch Fornés, JI.; Pons Martí, A.; Monsoriu Serra, JA.; Furlan, WD. (2014). The Effect of Fractal Contact Lenses on Peripheral Refraction in Myopic Model Eyes. Current Eye Research. 39(12):1-10. https://doi.org/10.3109/02713683.2014.903498S110391

IMI : global trends in myopia management attitudes and strategies in clinical practice : 2022 update

PURPOSE. Surveys in 2015 and 2019 identified a high level of eye care practitioner concern/activity about myopia, but the majority still prescribed single vision interventions to young myopes. This research aimed to provide updated information. METHODS. A self-administered, internet-based questionnaire was distributed in 13 languages, through professional bodies to eye care practitioners globally. The questions examined awareness of increasing myopia prevalence, perceived efficacy and adoption of available strategies, and reasons for not adopting specific strategies. RESULTS. Of the 3195 respondents, practitioners’ concern about the increasing frequency of pediatric myopia in their practices differed between continents (P < 0.001), being significantly higher in Asia (9.0 ± 1.5 of 10) than other continents (range 7.7–8.2; P ≤ 0.001). Overall, combination therapy was perceived by practitioners to be the most effective method of myopia control, followed by orthokeratology and pharmaceutical approaches. The least effective perceived methods were single vision distance undercorrection, spectacles and contact lenses, as well as bifocal spectacles. Practitioners rated their activity in myopia control between (6.6 ± 2.9 in South America to 7.9 ± 1.2/2.2 in Australasia and Asia). Single-vision spectacles are still the most prescribed option for progressing young myopia (32.2%), but this has decreased since 2019, and myopia control spectacles (15.2%), myopia control contact lenses (8.7%) and combination therapy (4.0%) are growing in popularity. CONCLUSIONS. More practitioners across the globe are practicing myopia control, but there are still significant differences between and within continents. Practitioners reported that embracing myopia control enhanced patient loyalty, increasing practice revenue and improving job satisfaction

Strategically oriented correction of mixed astigmatism in children

Purpose: evaluation of the remote functional and refractive results of mixed astigmatism correction in preschool children with “plus” cylinders in the framework of a long-time longitudinal study.Material and methods. 38 children (75 eyes) aged 1.5–7 years (averagely 4.2 years) with mixed astigmatism of 0.75 to 4.25 D (averagely 1.85 D) were followed up for 6-15 (averagely 7.3) years. At the first examination, all children were prescribed to permanently wear (+) cylinders of 0.5 D to 3.5 D. Over the follow-up period, (+) Cyl could be weakened in 24 eyes (32 %) due to a decrease in astigmatism, while (-) Sph had to be added in 24 eyes (32 %). due to an increased refraction. In cases when the full correction using a “plus” cylinder left an excessively large myopic defocus, the power of the “plus” cylinder was reduced so as not to add a “minus” sphere, and a second pair of glasses was prescribed for near vision, which offered a full correction of astigmatism with the “plus” cylinder.Results. After 6–15 years, astigmatism changed in 85 % of the examined eyes: it increased in 7 eyes (averagely, by 0.3 D) and decreased in 53 (averagely, by 0.9 D, p &lt; 0.05; with the maximum reduction of 2.75 D). The spheric-equivalent refraction changed in 51 % of eyes, with an average increase of 0.53 D. The maximum increase of refraction was 2.8 D, while the maximum drop was 1.4 D. Visual acuity of the children who wore the prescribed eyeglasses permanently, showed after two years an increase, average achieving the level of 0.84, which by the end of the follow-up period achieved 0.99.Conclusion. The proposed plan of mixed astigmatism correction, which preserves residual weak myopic defocus, fully ensured both tactical and strategic effects: prevention and elimination of amblyopia, and containment of refraction myopization

Changes of corneal epithelial thickness before and after OK-correction according to SD-OCT

Purpose: to evaluate the thickness of corneal epithelium after orthokeratological (OK) correction with the help of SDOCT. Material and methods: 18 patients (36 eyes) averagely aged 12.11 ± 1.68 with myopia of -3.21 ± 0.94 D and axial length of 24.47 ± 0.7 mm were examined. All patients were checked for corneal epithelial thickness (ET) with the help of SD-OCT Avanti RTVueXR (Optovue Inc., Fremont, CA, USA), which created maps of 6 mm in diameter before OK correction with lenses ESA-DL (Dr. Lens Technology, Russia) and 36.44 ± 5.81 days after it. A corneal ET map was divided into 17 sectors with average values indicated, and 3 zones (the central zone of 2 mm, the paracentral zone from 2 to 5 mm, and the mid-peripheral zone from 5 to 6 mm). We calculated the maximum (Max) and the minimum (Min) values of ET, the difference between them (Max Min) in the 5 mm zone, and standard deviation of values in the 5 mm zone (Std Dev). Results. The corneal ET showed no difference among the sectors of the 6-mm map (p > 0.05) before OK lenses were worn. The ET in the central zone was 53.1 ± 1.68 μm. The ET in the central zone decreased by 16.6 % from the initial value after 36.44 ± 5.81 days of OK correction, with a single sector (S) showing a statistically significant difference in the paracentral zone. In the mid-peripheral zone, the ET increased by 14.1 % from the reference. Max and Min ET, and Max-Min Std Dev in the 5-mm zone differed significantly after OK correction (p < 0.05). Conclusion. After OK correction, the ET significantly decreases in the central zone and increases in the mid-peripheral zone. These changes account for the flattening of the anterior corneal surface and contribute to the refractive effect of OK lenses. For citations: Milash S.V., Tarutta E.P. Changes of corneal epithelial thickness before and after OK-correction according to SD-OCT. Russian ophthalmological journal. 2017; 10 (3): 49-54. doi: 10.21516/2072-0076-2017-10-3-49-54 (in Russian)

A detailed examination protocol for evaluating the efficacy of myopia control methods

To ensure a reliable assessment of the efficacy of myopia control methods and their comparison, it is important that the studies are carried out according to identical protocols. Purpose. To analyze patient examination protocols used by different authors for assessing the efficacy of myopia control methods, and to evaluate the principles of forming the main (treatment) and control groups. Materials and methods. Domestic and foreign authors research works devoted to the assessment of myopia control methods were analyzed, most of which were randomized controlled studies. Results and Discussion. The authors propose their own protocol for evaluation of the efficacy of myopia control methods that includes methods for evaluating the results, recommended number (frequency) and duration of follow-up, represented as a checklist. Conclusion. The proposed protocol can be used for planning and executing a clinical research.Conflict of interest: the authors are members of the editorial board of the journal and recused themselves from review process and from making decision regarding acceptance of this article.</jats:p

THE IMPACT OF ORTHOKERATOLOGIC CONTACT LENSES ON SPHERICAL ABERRATION OF THE OPTICAL SYSTEM OF THE EYE

The purpose of this study is to measure the spherical aberration (SA) of the cornea and the optical system of the eye before and after wearing orthokeratologic (OK) contact lenses. Material and methods. 22 patients (44 eyes) with myopia aged 11 to 18 years were examined. The total SA was determined after medical cycloplegia performed on OPD-Scan III aberrometer, Nidek. To analyze SA values before and after wearing OK lenses, we chose pupil areas from 3 mm to 7.5 mm in 0.5-1 mm increments. Results. In intact eyes with myopia, the total SA is mildly positive and is growing with the increase of the pupil diameter. After OK correction, the SA is changing: from 3 to 6 mm of the pupillary area, the positive SA increases by 50-130 %, in the 6.3 mm area it falls sharply and becomes negative, growing on the way to the periphery of the pupillary area. Conclusions. Corneal topography changes after OK corrections lead to specific changes of the wavefront of myopic eyes, causing increased visual performance and eliminating the hyperopic defocus at retinal periphery. For citation: Tarutta E.P., Harutyunyan S.G. The impact of orthokeratologic contact lenses on spherical aberration of the optical system of the eye. Russian ophthalmological journal. 2018; 11 (2): 17-21. doi: 10.21516/2072-0076-2018-11-2-17-21 (In Russian)

Modern Methods for the Diagnosis of Morphological and Functional Features of the Retina in Dysbinocular and Anisometropic Amblyopia

Child health is a global health priority. Anomalies of refraction, complicated by amblyopia and squint, occupy one of the leading places in the pathology of the visual system of children. According to data obtained from 26 regions of Russia, the leading place in the ocular morbidity of children and adolescents is occupied by ametropia and strabismus with amblyopia. They account for up to 90 % of all cases of visual impairment in childhood. The term amblyopia is understood to mean a decrease in the maximum corrected visual acuity that occurred at an early age, which is caused by disorders of the functions of the visual analyzer, without changes in the fundus and organic lesions of the visual pathways and centers. Despite the outstanding achievements of 21st century medicine, today the questions of the pathophysiological essence of this condition remain open, which is the subject of discussions among pediatric ophthalmologists around the world. In this regard, the literature review presents the results of domestic and foreign authors who studied the morphological (optical coherence tomography) and functional (electroretinography, microperimetry) features of the retina in dysbinocular and anisometropic amblyopia. Some authors have demonstrated the presence of differences in the thickness of the central region and the layer of nerve fibers in patients with amblyopia compared with paired and healthy eyes, their correlation with functional parameters, as well as changes in the thickness of the choroid and microvasculature of the retina. Recently, there have been works devoted to the study of the photosensitivity of the retina in patients with amblyopia and visual rehabilitation using this equipment. A number of authors have shown that with amblyopia, the retinal photosensitivity parameters in the central region are reduced, and there is a correlation between these changes and morphological changes in the posterior pole. The microperimeter also makes it possible to carry out visual rehabilitation, in particular in pediatric patients, and isolated results have been published on the use of this method in patients with amblyopia. The literature data are quite contradictory, and more research remains to be done to determine whether these changes in the retina are primary in relation to this disease, or whether they can be the result of retrograde changes that are obscured by defocusing of visual images from birth.</jats:p