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

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)

Wavefront aberrations in children with myopia and hyperopia before and after cycloplegia

Purpose: a comparative study of the effect of cycloplegia on wavefront aberration in children with myopia and hyperopia. Material and methods. The study involved 20 patients (39 eyes) with myopic refraction (averagely -5.2 ± 1,5 D) and 26 patients (52 eyes) with hyperopic refraction (averagely +3.1 ± 1.15 D), aged 5 to 17 (mean age 11.6 ± 0.6 years). All patients underwent wavefront aberrometry in a darkened room before and after a cycloplegic drug administration (1 % cyclopentolate dehydrochloride 2 times with an interval of 10 minutes, aberrometry 30 minutes after the first instillation) using the aberrometer OPD-Scan III, Nidek. Aberrations of the lower and higher orders were analyzed with a pupil 3 mm wide, both without and under cycloplegia (in the latter case, a 3 mm band was chosen). Total aberrations (RMS) were studied. Zernike coefficients were used to calculate the standard deviation of total higher order aberrations (RMS HOAs), the vertical and the horizontal tilt (C1-tilt1, C2-tilt2), the vertical and horizontal trefoil (C5-trefoil 6, C8-trefoil 9), the vertical and horizontal coma (C6-coma7, C7-coma8), and spherical aberration (S4 + S8 + S12). Results. Both myopia and hyperopia treated with cycloplegia showed a statistically insignificant increasing trend of higher order aberrations and spherical aberration. Under natural conditions, the levels of tilt1 aberration, horizontal trefoil and coma7 proved significantly higher in myopia than in hyperopia, while coma8 and tilt2 turned out to be significantly lower than in hyperopia. In myopic eyes, no significant changes were found in any of the examined HOAs after cycloplegiaas compared to the initial state. In contrast, significant changes were found in hyperopia: an increase in horizontal trefoil and a decrease in horizontal coma. An insignificant trend towards an increase in Tilt1 and coma7 and toward a reduction in the vertical trefoil and tilt2 was revaeled. Conclusions. Under natural conditions, a 3-mm wide pupil shows no statistically significant difference between the total level of aberrations of the optical system of the myopic eye and hyperopic eyes in children, while the the wavefront structures in these groups demonstrate essential differences. The differences revealed in the wavefront structure and its dynamics under cycloplegia may indicate differences in the accommodation apparatus, in particular, the ciliary muscles and ligaments of the lens for myopia and hyperopia. For citations: Tarutta E.P., Аrutyunyan S.G., Smirnova T.S. Wavefront aberrations in children with myopia and hyperopia before and after cycloplegia. Russian ophthalmological journal. 2017; 10 (3): 78-83. doi: 10.21516/2072-0076-2017-10-3-78-83 (in Russian)

A symmetric hypocorrection of myopia by FemtoLASIK in patients with presbyopia

Purpose: to evaluate the results of symmetric binocular hypocorrection of myopia with FemtoLasik surgery in patients with presbyopia of various age groups.Material and methods. 33 patients (66 eyes) with myopic refraction, aged 36 to 50, were operated by FemtoLasik. The intended Femto Flap thickness was 100 μm. The patients were divided into three groups depending on age; group 1 included 16 patients (32 eyes) aged 39–44, group 2 had 12 patients (24 eyes) aged 45–50, and group 3 (controls) was composed of 5 patients (10 eyes) of pre-presbyopic age (36–38 years).Results. The symmetric binocular hypocorrection proved efficient in 35 % of cases in the group 1 and 50 % of cases in group 2. In the control group the intended and obtained values coincided in all 100 % of cases.Conclusion. A possible cause of the discrepancy between the intended and the obtained hypocorrection effect may be a reduced corneal hydration of patients older than 39 years

Multi-Factoral Mechanisms of Therapeutic Effect of Perifocal Spectacles (Perifocal-M) on Progressive Myopia in Children

There is detailed review of multi-factoral mechanisms of spectacles with peripheral defocus influence in children with progressive myopia in this article. At present local retinal mechanisms of neuro-regulatory control of eye growth are most effective in prevention of myopia development and progression. Optical correction of relative peripheral hyperopia with following peripheral myopic defocus affects the biochemical cascade from retina to choroid and sclera, which constrains an eye growth. Optical methods of myopia control, including spectacles, widely used in native and foreign ophthalmology practice. Since 2011, in Russia Perifocal-M spectacles are using, said spectacles provides bigger functionality of influence on myopic eye comparing to foreign analogues. Construction features of said spectacle lens have a complex influence on different optic-physiological eye structures and each of said structures affects refractogenesis. Perifocal spectacles takes into account specific for myopic eye features of central and peripheral refraction along horizontal and vertical meridians. They have stronger refraction in horizontal, which allows to eliminate specific optical disbalance in myopic eye and to create optical balance in the eye. Perifocal-M lens construction with asymmetric horizontal progression allows to correct relative peripheral hyperopia, to create myopic defocus in horizontal and to affect relations between refraction of nasal and temporal halves of retina. The latter is due to the fact that optical influence starts earlier and has bigger effect on nasal half of retina relative to temporal. Perifocal spectacles are inducing positive spherical aberrations in the eye, increasing accommodation functions, supporting high binocular visual acuity, improving binocular interaction during near work, fighting against heteroforias. Thus, optical features of Perifocal-M spectacles for the first time creates conditions for versatile functional influence on main myopogenic factors simultaneously, it effectively stops myopia progression

The Dynamics of Peripheral Refraction and Eye Shape in Children with Progressive Myopia Wearing Orthokeratology Lenses

The change of peripheral refraction and the shape of 52 myopic eyes of 26 patients aged 8 to 16 (averagely, 10.4 ± 0,9 years) resulting from overnight wearing of orthokeratology lenses was followed up for 3.2 ± 0.9 years on average. The use of Ortho-k lenses was found to form relative peripheral myopia, whose value correlated with the initial degree of myopia and was averagely equal to -1.4 ± 0.13 D, -1.9 ± 0.17 D and -4.4 ± 0.13 D, respectively for low, moderate and high myopia. The ratio coefficient APA/HD between the length of the anterioposterior axis (APA) and the horizontal diameter (HD) of the eye changed from the initial value, which was averagely equal to 1.01 ± 0.06 (1.00 ± 0.002 for low myopia, 1.01 ± 0.008 for moderate myopia, and 1.02 ± 0.003 for high myopia), to -0.98 ± 0.006 (-0.94 ± 0.001 for low myopia, 0.98 ± 0.007 for moderate myopia, and - 1.00 ± 0.006 for high myopia) by the end of lens wearing term. This dynamics of APA/HD variation is an evidence of eyeball shape change as a result of prolonged use of ortho-k lenses toward the shape of a oblate ellipsoid. This is accompanied by the formation of a peripheral myopic defocus // Russian Ophthalmological Journal, 2016; 1: 62-6

Choroidal thickness in varied types of refraction and its changes after sclera strengthening surgeries

Purpose: to study the choroidal thickness in children with varied refractions and its dynamics after sclera reinforcement treatment. Material and methods. The study involved two groups: (1) 78 children (average age 12.54 ± 0.35 yrs) with mild hyperopia, low, moderate and high myopia and (2) 40 children with moderate and high myopia who received low invasive (LSP, average age 12.00 ± 0.51 yrs.), or bandaging scleroplasty (BSP, average age 12.33 ± 0.35 yrs) according to Snyder and Thompson and were examined prior to and after the procedure. All patients underwent a standard ophthalmologic examination and had choroid thickness (CT) manually measured by EDI-SD-OCT technique. Results. In group 1, a drop in CТ with refraction growth and axial elongation was found. In group 2, the CT change was traced: in the operated eyes, СТ increased by 34.7 ± 3.15 μm after LSP and by 53.7 ± 1.19 μm after BSP. In fellow eyes, CT showed an increase of 25.4 ± 1.79 μm after LSP and 32.20 ± 0.59 μm after BSP. Conclusions. In the early period after sclera strengthening operations, СТ significantly increases both in the operated and in the fellow eye. Аn increase of CТ probably stimulates collagen biosynthetic activity of the scleral matrix and collagen synthesis, and boosts the inhibitory effect of scleroplasty with regard to myopia progression. For citations: Tarutta E.P., Markossian G.A., Sianosyan А.А., Milash S.V. Choroidal thickness in varied types of refraction and its changes after sclera-strengthening surgeries. Russian ophthalmological journal. 2017; 10 (4): 48-53. doi: 10.21516/2072-0076-2017-10-4-48-53 (In Russian)

Can the progression of myopia be restrained by monolateral excimer laser correction?

The purpose of this study was a comparative assessment of the refraction and the axial length (AL)  changes occurring in the operated and unoperated  eyes of patients with anisometropic  myopia who underwent  unilateral  excimer laser correction.Material  and methods. We observed 13 patients (8 women and 5 men) aged 21 to 53 years (34.2 ± 8.6) with anisometropic myopia (averagely, with spherical equivalent of refraction -3.87 ± 1.77 D in one eye and 0.71 ± 0.71 D in the other), who underwent unilateral LASIK. The observation period was 3-5 years (averagely 3.5 ± 1.1 years). The observation included autorefractometry on a Nidek ARK-530A apparatus, ultrasound biometry on a Nidek US-1800 Echosсan (Japan), and pachymetry on a GALILEI G6 (Ziemer, Switzerland).Results. No significant changes in refraction or axial length were observed either in operated or fellow eyes. Changes in the axial length were controversial: 7 operated and 7 fellow eyes showed an increasing tendency while another 6 operated and 6 fellow eyes showed a decreasing tendency (p &gt; 0.05).Conclusion. The data obtained fail to support the assumption that excimer laser reshaping of the cornea produces an inhibitory effect on the development of myopia

OBJECTIVE ACCOMMODATION RESPONSE VALUE (COMPLETENESS OF CYCLOPLEGIA) AFTER DIAGNOSTIC INSTILLATIONS OF DIVERSE MEDICATIONS

Today, a variety of medications are used in ophthalmology practice to o produce cycloplegia and mydriasis. Purpose: to compare the extent of cycloplegia by residual accommodation response after instillations of various medications. Materials and methods. 54 patients, aged 8 to 23, with varied degrees of myopia were instilled twice, with an interval of 10 minutes, with one of the following medications: Cyclopentolate 1 %, Tropicamide 1 %, Midrimax, and Phenylephrine 2.5 %. The patients were examined before the first instillation and 40 minutes after it using autorefractometry and measurement of objective monocular accommodation response (MAO) with a Grand Seiko Binocular Open Field Autorefkeratometer WR-5100K. The value of MOA, i.e. residual accommodation, was used to assess the completeness of cycloplegia. Results. The difference between manifest and cycloplegic refraction was -0.13 D after Cyclopentolate, -0.2 D after Tropicamide, -0.11 D after Midrimax, and -0.02 D after Phenylephrine. No intergroup differences in this parameter were noted (р > 0.05). MAO fell after Tropicamide and Midrimax but remained sufficiently high: -0.83 D and -0.71 D, respectively. Phenylephrine had no paralyzing action on the ciliary muscle; it even strengthened slightly (by 0.12 D) the objective accommodation response. The only medication to provide true cycloplegia was Cyclopentolate 1%: upon presentation of an accommodation task of 3.0 D, МАО was found to be only -0.1 D. The difference in MAO after Cyclopentolate 1% and all other medications is statistically significant, р < 0.05. Conclusion. For a dynamic observation of patients with no suspicion of elevated tone of the ciliary muscle, Cyclopentolate, Tropicamide and Midrimax are equally effective. In cases of primary examination or if a habitually excessive accommodation strain or accommodation spasm is observed, Cyclopentolate or Atropine must be used. Phenylephrine 2.5 % is a curative medication which normalizes the tone of the ciliary muscle and heightens the accommodation response. It is not advisable to use it for diagnostic purposes as mydriasis is weak and cyloplegia is absent. For citation: Tarasova N.A., Tarutta E.P., Markosian G.A., Maksimova M.V. Objective accommodation response value (completeness of cycloplegia) after diagnostic instillations of diverse medications. Russian ophthalmological journal. 2018; 11 (2): 22-6. doi: 10.21516/2072-0076-2018-11-2-22-26 (In Russian)