Bifocal Contact Research Articles

Do diffractive intraocular lenses break the beneficial interaction between chromatic and monochromatic aberrations in the eye?

This study investigates whether a diffractive presbyopia-correcting multifocal intraocular lens disrupts the favorable interaction between chromatic and monochromatic aberrations in the eye. This is analyzed not only for distant objects but also for closer viewing distances, where the lens utilizes different diffraction orders depending on its design. We consider diffractive designs based on the zero-diffraction order for far vision and the first diffraction order for near vision (i.e., 0F/+1N design). Within the limitations of clinical visual acuity examination in various groups of subjects, our results prove that diffractive presbyopia-correcting lenses with 0F/+1N design preserve the beneficial interaction between chromatic and monochromatic aberrations at both far and near vision. The results are obtained for lenses with varying energy efficiency distributions between the far and near focal points, ranging from balanced (bifocal contact lens) to far-dominant (50% far, 30% near in a trifocal intraocular lens) configurations. These findings are specific to the 0F/+1N design and cannot be extrapolated to other diffractive lens types.

Myopie-Management vom Kind zum Erwachsenen anhand eines Fallberichts

Purpose: The case report describes the successes and lessons learned from optical therapeutic management of progressive myopia, based on long-term treatment plan and the resulting development of the correction and axial lengths of a female patient from age 8 to 22 years. Material and Methods: Using a risk analysis and adaptive care plan, with age-appropriate contact optic care, an attempt was made to positively inhibit, the progression of myopia in a young female patient from 2009 to 2023. The scientific facts and contact lens techniques available at the time of treatment, were applied such as analysis of environmental factors, use of bifocal silicone hydrogel contact lenses and orthokeratology. Results: By using orthokeratology contact lenses, the increase in myopia and axial length growth could be clinically inhibited over several years. Early setbacks during the treatment period due to ineffective measures or early treatment cessation (partial rebound effect) could be stopped or stabilized due to the increasing age of the patient. Conclusion: By means of targeted and controlled contact lens treatment, it is possible to successfully inhibit the progression and thus mitigate the subsequent, secondary health risk.

Chromatic changes in vision with diffractive ophthalmic optics.

Diffractive optics is a valuable technique for designing presbyopia-correcting lenses, but its effectiveness is wavelength-dependent. This study investigates the spatio-chromatic alterations in visual resolution associated with diffractive multifocal lenses by using non-invasive, removable diffractive bifocal contact lenses. The study combines theoretical analysis, numerical simulation, and clinical intra-observer experiments to assess visual acuity under various lighting conditions. Results demonstrate the introduction of spatio-chromatic asymmetry and a change in visual acuity under red and blue lights, depending on the operating diffraction order employed in the lens design. The energy distribution of the diffractive contact lens studied favors resolution under red illumination at far distances and under blue illumination at near distances. These findings are consistent with computational simulations and provide insights into the visual changes induced by diffractive ophthalmic lenses.

Poster Session: Perceived image quality of natural images through different bifocal corrections after adaptation to sharp or blur.

Simultaneous Vision, present in bifocal and multifocal contact or intraocular lenses, is a common clinical strategy for presbyopia. Neural adaptation is known to occur, but it is not predictable nor well understood. Previous works have studied the short-term neural adaptation to bifocal images using Adaptive Optics and digital convolutions of a face image (with pure defocus and simultaneous images) as adaptation images, and also as test images for perceptual judgments (Radhakrishnan et al., 2014). In this study, we use a programmable see-through head-mounted visual simulator (SimVis Gekko) to analyze the effect of neural adaptation on the perceived image quality of different bifocal corrections (BC) with different balances of energy between far and near, and for different transitions between adaptation and test. Eight subjects judged a video sequence of urban natural images, through two monofocal corrections (0 and 3D) and nine BCs (far/near balance from 90/10 to 10/90 and an addition of 3.00D), optically simulated monocularly. Two initial adaptation states of 10s were used: 0.00D-SHARP and 3.00D-BLUR, followed a transition from these states to the BC that can be ABRUPT (with 1, 5 or 30s of adaptation), or SMOOTH (linear transition lasting 1, 5 or 30s). Our results show a significant increase in perceptual quality after adaptation to BLUR, particularly for intermediate energy balances. However, subjects are quite insensitive to the type and duration of the transition.

Optical methods for the management of progressive myopia

Introduction. Myopia is the main cause of preventable blindness and is widespread around the world at an alarming rate, especially in Asian countries. The age of the onset of myopia is getting younger. The prevalence of myopia and high myopia is sharply increasing, which requires clinicians to use new and safe methods of its stabilization. The main methods of correction are optical. This group is based on the hypothesis of induced peripheral myopic defocus.Aim: to study the domestic and international experience with the use of the optical methods in treatment of progressive myopia according to the literature and factors, as well as factors affecting their effectiveness.Materials and methods. More than 200 publications on PubMed, eLibrary, and Crossref Metadata over the past 10 years were analyzed. Our analysis includes a review of 60 publications.Results. Over the past years, there has been a strong interest of researchers in the problem of progressive myopia. This is reflected by a more than four-fold increase in the number of publications devoted to the causes and methods of treatment in patients with progressive myopia. Publications demonstrate the importance of using the modern optical methods, such as spectacle lenses, multifocal and bifocal soft contact lenses and orthokeratology in the routine practice of ophthalmologists and optometrists in order to stabilize the progression of myopia in children and adolescents. On the one hand, the results of analysis show their high efficiency. On the other hand, we need an individual approach in choosing the method for myopia control in each specific case. The factors influencing the result are identified: the diameter of the optical zone, the force of addition that creates the peripheral myopic defocus and the time of use myopia correction during the day.Conclusion. No method of treating progressive myopia demonstrates clear superiority. Orthokeratology, multifocal and bifocal soft contact lenses, special glasses and low doses atropine instillation demonstrates the similar effect with some clauses. When choosing optical methods for myopia control, the factors affecting their effectiveness should be taken into account.

Induced bifocal soft contact lenses with the addition of 4.0 D myopic defocus in the near periphery of the retina and its effect on the progression of myopia

AIM: To evaluate the dynamics of axial and peripheral refraction in the near periphery of the retina in eyes with myopia against the background of wearing bifocal soft contact lens (BSCL) with the addition of 4 D.
 MATERIAL AND METHODS: Forty-three patients (84 eyes) with myopia from 0.5 to 6.5 D (average 3.530.19 D) aged 715 (average 11.30.27) years were examined before and 6 months after the start of wearing Prima BIO Bifocal BSCL (Okey Vision Retail, Russia). Visual acuity without correction, with optimal correction, and in BSCL, cycloplegic refraction, eye length, keratotopography, and peripheral defocus (PD) at 5, 10, and 15 to the nose and temple from the center of the fovea with and without lenses were assessed.
 RESULTS: After 6 months of wearing BSCL, the subjective refraction increased by 0.04 D, cycloplegic refraction by 0.18 D, and average BSCL strength by 0.01 D. The axial length increased by 0.03 mm (p 0.05). The initial PD without lenses was hypermetropic in all zones, and in BSCL, it was myopic in zones T5, T10, T15, and N15 and hypermetropic in zones N5 and N10. After 6 months of PD without correction, hypermetropic defocus tended to decrease in zones N10 and N15 and myopic defocus appeared in N5 (p 0.05); with lenses, myopic defocus increased in zones T5, T10, T15, and N15, and in N5 and N10, it did not change and remained hypermetropic.
 CONCLUSION: BSCLs provide total correction of myopia and high distant and near visual acuity in children, induce myopic defocus in the near periphery, and contribute to the inhibition of the progression of myopia in the traced period.

Changes in the Axial Length of the Eye and Refraction in Children with Progressive Myopia while Wearing Defocused Contact Lenses

Progressive myopia remains one of the urgent problems in modern ophthalmology. Optical methods for controlling progressive myopia suggest the formation of peripheral myopic defocus, which has a stabilizing effect on the axial length of the eye and, as a result, the degree of myopia. One option for optical control of myopia is defocus soft contact lenses.Purpose: to evaluate the growth of axial length and changes in the spherical equivalent of clinical refraction in users of defocus (bifocal) contact lenses and monofocal glasses expressed in diopters, against the background of the correction of progressive myopia with defocus (bifocal) contact lenses and monofocal glasses.Materials and methods. The study involved 256 patients with bilateral mild to moderate and high myopia in the range from (–)0.5 to (–) 7.75 D in spherical equivalent and an annual progression gradient from 0.65 to 1.5 D in the age categories 7–10, 11–14, 15–18 years old. Depending on the degree of myopia and the method of correction, the patients were divided into main and control groups. For correction in the main groups, defocused (with an addition of +4.0 D) soft contact lenses (SCLs) were used. In the control groups monofocal glasses were used. All patients underwent a standard ophthalmological examination. Clinical refraction data and axial length of the eye were used as criteria for evaluating the results. The follow-up period was 3, 6, 12 months.Results. After 12 months of wearing bifocal soft contact lenses, there was a statistically significant slowdown in the growth of the axial length and the spherical equivalent of refraction Higher rates of progression of myopia were in young children (7–10 years). Myopia at the age of 15–18 years is characterized by a decrease in the rate of progression with any type of optical correction and in most cases does not require the appointment of correction with the formation of peripheral myopic defocus.Conclusion. The results obtained indicate the effectiveness of the use of bifocal SCLs in the control of progressive mild, moderate and high myopia. The main stabilization factor is the formation of peripheral myopic defocus on the retina, followed by a slowdown in the growth of the axial length of the eye and the degree of myopia (spherical equivalent of clinical refraction).

The influence of contact lenses with different optical designs on the binocular vision and visual behavior of young adults

Theoretically, contact lenses change the accommodation and vergence demands of the eyes and directly or indirectly influence binocular vision. The purpose of this study was to investigate the influence of different optical designs of contact lenses on binocular vision and visual behavior among young adults. In this randomized, single-blinded experimental study, visual behavioral performance (VBP) and Ocular Surface Disease Index questionnaires were used for preliminary screening. Nineteen myopic subjects aged 20–26 years (21.59 ± 1.40 years) participated in the study. Baseline values for subjective refraction and binocular visual functions were evaluated. All the subjects were randomly grouped to wear different optical designs of single-vision, progressive, and bifocal contact lenses. Eye examinations were performed on the first day (CL baseline), 2nd week, and 4th week of wearing the lenses. In addition, subjects completed the VBP and visual quality questionnaire again at the end of the examination. Single-vision contact lenses (Lens 1) increased accommodative lag, negative relative accommodation, and distant and near vergence; however, vergence facilities, accommodative facilities, heterophoria, and the comfort and posture balance dimensions in the VBP questionnaire were improved. Progressive contact lenses (Lens 2) reduced the lag of accommodation and near vergence; in addition, vergence facilities and accommodative facilities were also improved. Bifocal contact lenses (Lens 3) affected negative and positive relative accommodation, but vergence facilities and accommodative facilities also progressed. Furthermore, both progressive (Lens 2) and bifocal (Lens 3) contact lenses enhanced overall visual behavioral performance. In terms of visual quality, single-vision contact lenses (Lens 1) were the most comfortable, progressive and bifocal contact lenses reduced distant visual acuity and stability, progressive contact lenses (Lens 2) had more complaints about halos at night, and bifocal contact lens (Lens 3) users were more likely to have double vision. Compared with single-vision contact lenses, progressive and bifocal contact lenses relaxed accommodation, reduced the lag of accommodation, and improved visual behavioral performance. Although the vergence function showed a significant change, it did not show worse trends when wearing contact lenses. Contact lenses with different optical designs have a great influence on binocular vision and visual behavioral performance.

The issue of juvenile myopia from the parents’ point of view

The success of preventing the development and progression of myopia in children depends on establishing compliance between the doctor and the patient (parents).Purpose: to study the attitude of parents of myopic children towards the issue of myopia and methods of its control.Materials and methods. 106 doctors from 53 regions of Russia and 2931 parents of myopic children took part in a prospective multicenter epidemiological observational study in the form of a questionnaire.Results. As preferable interventions to control myopia, parents mention single vision glasses (67.9 %), glasses with perifocal lenses (16.3 %), bifocal or progressive glasses (3.4 %), other types of glasses (1.6 %), soft contact lenses (11.5 %), orthokeratology lenses (5.8 %), while 13.8 % of myopic children do not use any of those. The average time that children spend on visual work amounts to 10 hours a day, while their light-time daily outdoor activities last for 2.12 ± 1.39 hours. Only 27.1 % of the parents surveyed follow all recommendations of the eye doctor. The reasons for not following are lack of time (45.1 %), complexity of implementation (7.3 %), high cost of treatment (8.5 %), other reasons (39.1 %). Parents consider that the most effective interventions to control myopia are eye drops instillation courses (53.4 %), device-assisted therapy (59.6 %), home visual gymnastics (52.4 %), orthokeratology lenses (13.7 %), bifocal soft contact lenses (4.6 %), specialty glasses (22.7 %), vitamins intake (44.4 %), while 10.6 % believe opinion that no effective myopia control methods exist.Conclusion. Parents choose single vision glasses as the main optical interventi on method. Near visual work significantly reduces physical activity in the children’s daily routine. Parents’ failure to comply with the medical advice is mostly due to lack of time. The most effective methods of myopia control are considered to be pharmacological treatment, device-assisted therapy and home visual gymnastics.

The effect of optic zone diameter on choroidal response using bifocal soft multifocal contact lenses

The effect of optic zone diameter on choroidal response using bifocal soft multifocal contact lenses

Changes in subfoveal choroidal thickness in myopic children who wear bifocal soft contact lenses

To study the changes in subfoveal choroidal thickness in children with progressive myopia who have been wearing bifocal soft contact lenses (BSCL) with an ADD power of +4.0 D for 3 months. The study included 40 patients (80 eyes) with progressive myopia of low and moderate degrees. The main group consisted of 23 patients aged 10.04±1.5 years with an average myopia of -3.06±1.17 D, they were examined before and 3 months after vision correction with bifocal soft contact lenses Prima BIO Bi-focal («OkVision Retail», Russia). The control group consisted of 17 patients (34 eyes) aged 9.29±0.92 years with an average myopia of -3.05±1.5 D using single vision spectacle lenses. Cycloplegic refraction, choroidal thickness and axial length were measured in all patients before and after 3 months. Choroidal thickness was measured using the semi-automatic method on the optical coherent tomography system RS-3000 Advance 2 («Nidek», Japan). Axial length was measured using the optical biometer IOL Master 500 («Carl Zeiss», Germany). In the main group, subfoveolar choroidal thickness increased on average by 15.3±24.3 μm after 3 months of wearing BSCL, and in the control group it decreased on average by 9.03±28.65 μm. Comparison of changes in choroidal thickness between the main and the control groups revealed a significant difference (p<0.001). Increase in axial length of the eye in the main group was significantly less than in the control group (0.005±0.08 mm vs 0.07±0.06 mm; p<0.001). A strong negative correlation was found between changes in the axial length and subfoveolar choroidal thickness in the main group (r= -0.67), but no similar relationship was found in the control group (r= -0.13). Subfoveolar choroidal thickness increases in children wearing bifocal soft contact lenses for myopia correction.

Wearable Bifocal Contact Lens for Continual Glucose Monitoring Integrated with Smartphone Readers.

Commercial implantable continuous glucose monitoring devices are invasive and discomfort. Here, a minimally-invasive glucose detection system is developed to provide quantitative glucose measurements continually based on bifocal contact lenses. A glucose-sensitive phenylboronic acid derivative is immobilized in a hydrogel matrix and the surface of the hydrogel is imprinted with a Fresnel lens. The glucose-responsive hydrogel is attached to a commercial soft contact lens to be transformed into a bifocal contact lens. The contact lens showed bifocal lengths; far-field focal length originated from the contact lens' curvature, and near-field focal length resulting from the Fresnel lens. When tear glucose increased, the refractive index and groove depth of the Fresnel lens changed, shifting the near-field focal length and the light focusing efficiency. The recorded optical signals are detected at an identical distance far from the contact lens change. The bifocal contact lens allowed for detecting the tear glucose concentration within the physiological range of healthy individuals and diabetics (0.0-3.3mm). The contact lens rapidly responded to glucose concentration changes and reached 90% of equilibrium within 40min. The bifocal contact lens is a wearable diagnostic platform for continual biomarker detection at point-of-care settings.

Peripheral Refraction, Wave Front of the Eye and Visual Performance in the Correction of Myopia in Children with Bifocal Soft Contact Lenses with High Addition

Purpose: to study the effect of bifocal soft contact lens (BSCL) with an ADD of 4 diopters on peripheral refraction (PR), optical and ergonomic eye parameters in children with myopia.Patients and methods. 26 patients (52 eyes) with myopia –3.09 ± 1.13 diopters at the age of 10.04 ± 1.5 years without correction and with correction by BSCL Prima BIO Bi-focal ( Okay Vision Retail, Russia). All patients underwent a horizontal and vertical PR study on an open field autorefractometer Grand Seiko WAM-5500 (Japan), wavefront aberrations were studied on OPD-Scan III aberrometer (Nidek, Japan), contrast sensitivity under mesopic conditions were studied on a Mesotest 2 instrument (Oculus, Germany) and visual productivity was studied using test tables.Results. The visual acuity of the distance with a BSCL correction of 0.98 ± 0.04 did not differ (p = 0.26) from the maximum visual acuity corrected by spherocylindrical glasses of 0.99 ± 0.04. BSCL induces myopic defocus in all peripheral zones, with a maximum value of 15° and a sharp decrease of 30°. Peripheral myopic defocus induced by the lens at a horizontal and vertical angle of 15 degrees did not depend on the initial degree of myopia. BSCL increases the total RMS from 0.07 ± 0.02 μm to 0.19 ± 0.07 μm in the 3 mm zone (p &lt; 0.01) and from 0.27 ± 0.09 μm to 1.18 ± 0, 23 μm in the 6 mm zone (p &lt; 0.01), mainly due to an increase in spherical aberration from –0.0005 ± 0.006 μm to 0.06 ± 0.01 μm (p &lt; 0.01) and from 0.01 ± 0.09 μm to 0.58 ± 0.14 μm (p &lt; 0.01) in the 3 mm and 6 mm zones, respectively. An increase in the overall RMS in BSCL reduces the quality of eye optics and contrast sensitivity under mesopic conditions, but does not impair visual productivity.Conclusion. BSCLs with a high ADD of 4 diopters are capable of inducing significant myopic peripheral defocus due to the induction of spherical aberration, while maintaining high visual acuity and not changing ophthalmic ergonomics, which makes them a pathogenetically substantiated method for correcting myopia and preventing its progression in children and adolescents.

Our Experience of Using Soft Bifocal Contact Lenses in Children with Progressive Myopia

Introduction. According to the studies, one out of three myopic patients with refraction greater than –6.00 D and an axial length greater than 26 mm is at high risk of facing low vision and loss of sight in the future. According to the results of medical examinations and screenings in carried out in Ivanovo, the prevalence of myopia in primary school children has increased three times during the past twenty years. Myopic children under 7 years old are six times more likely to have myopia progressed to higher degrees than children in which myopia onset took place later (at the age of 11–12 years). Optical interventions for myopia control such as orthokeratology and soft bifocal contact lenses have a strong body of evidence and are well accepted by ophthalmologists.Purpose. The purpose of the present study was to investigate the effect of soft bifocal contact lenses on refraction, accommodation and axial length in children with progressive myopia.Materials and methods. We observed 30 children aged 8–15 years with myopia progression rate of 0.82 D/year and accommodative weakness and instability. We prescribed OKVision PrimaBio Bi-focal design soft bifocal contact lenses (OKVision, Russia) that feature +4.00 D addition power on periphery. The effectiveness was estimated by monitoring refraction, accommodation and axial length every three months within a year.Results. After 12 months of wearing soft bifocal contact lenses, the annual myopia progression rate decreased 4.3 times on average. We were able to stabilize myopia in 50% of the children during the period of monitoring. The use of this intervention had a strong effect on accommodation resulting in an increase of its amplitude and reserve.Conclusion. The use of soft bifocal contact lenses has been proven to have a strong inhibitory effect on myopia progression rate. Myopia stabilization manifested itself as the absence of increase in myopic refraction and axial length as well as normalization of accommodative function.

Влияние оптических методов коррекции на гармонизацию аккомодации у детей с прогрессирующей миопией

Accommodation disorders in young people are more common than diagnosed. This review is based on the data of domestic and foreign literature and studies the effect of contact lenses of various designs on accommodation. Particular attention has been given to bifocal soft contact lenses as one of the recognized interventions for treating juvenile progressive myopia and their ability to slow axial elongation. Key words: accommodation, myopia control, bifocal contact lenses, orthokeratology.

Accommodation Dynamics in Children Wearing Bifocal Soft Contact Lenses with High Addition Power

Purpose: to evaluate dynamics of subjective and objective accommodation in children wearing bifocal soft contact lenses (BSCLs) for myopia control with +4.00 D addition power. M e t h o d s: the study involved 22 patients (44 eyes).Mean age amounted to 10.1 ± 1.46 years and mean myopic refraction amounted to –3.21 ± 1.23 D. Patients were fitted Prima BIO Bi-focal BSCLs (OKVision Retail, Russia). All patients underwent cycloplegic refraction assessed with Auto Ref/Keratometer ARK 530A (Nidek, Japan), had axial length measured with IOL Master 500 optical biometry device (Carl Zeiss, Germany), had positive relative accommodation (PRA) assessed with and without lenses and had binocular (BAR) and monocular (MAR) accommodative response assessed at a distance of 33 cm with WAM-5500 Binocular Accommodation Auto Ref/Keratometer (Grand Seiko, Japan) prior to wearing BSCLs as well as 3, 6 and 12 months after wearing BSCLs.Results: neither MAR nor BAR measured without lenses changed after 3, 6 and 12 months of wearing BSCLs (p &gt;0,05). A change in PRA evaluated without lenses was noted after 12 months (p &lt; 0,05). PRA evaluated with lenses after 3, 6 and 12 months differed from baseline significantly (p &lt; 0,001). Over 12 months of wearing BSCLs, changes in AL (0.09 ± 0.17 mm) and cycloplegic refraction (0.3 ±0.43 D) correlated with baseline BAR and MAR loosely. C o n c l u s i o n: objective accommodation (MAR and BAR) did not change in the course of wearing BSCLs with +4.00 D addition power. Increase in PRA evaluated without BSCLs may be associated with improvement of accommodation due to a full correction in the optic zone. The gradual increase in PRA evaluated with BSCLs probably indicates an adaptation of patients to addition zone in near vision conditions.

Results of a two-year clinical study of myopia control with bifocal defocus-inducing soft contact lenses

To review the results of a two-year multicenter clinical study of myopia control with bifocal defocus-inducing SCLs. The two-year study enrolled 100 patients aged 8 to 16 years who had mild or moderate bilateral myopia with spherical equivalent of (-)0.25 to (-)5.75 D. Based on the degree of myopia and the method of its correction, patients were divided into two main and two control groups. Multifocal SCLs with +4.0 D add power and monofocal SCLs were used for myopia correction. The results were evaluated by the clinical data of refraction, axial length and state of accommodation. The observation times were 3, 6, 12, 18 and 24 months. After 12 months of bifocal SCLs usage, signs of stabilization of myopia progression were identified in 72 and 73.5% of subjects of both main groups, after 24 months - in 54 and 79.5% of subjects, respectively. Statistically significant reduction in axial elongation amounting to 87-88% was also observed in patients using bifocal SCLs. A significant increase in positive relative accommodation (PRA) was observed in all groups. The study indicates the effectiveness of bifocal soft contact lenses in slowing the progression of mild and moderate myopia.

Multifocal contact lenses: A bibliometric study

PurposeTo analyze the state of scientific publications in multifocal contact lenses field through a bibliometric study. MethodsThe database used to carry out the study was SCOPUS and contained the descriptors “multifocal contact lens”, “bifocal contact lenses”, “progressive contact lenses” and “presbyopia contact lenses”, limited to the fields of title, keywords and abstract. The indicators applied in this research were: doubling time and annual growth rate, Price’s transience index, Lotka’s law of scientific productivity, and Bradford’s zones. ResultsA total of 346 articles were published between 1960 and 2019. The growth in the number of publications matches the exponential adjustment slightly better (R = 0.53). The duplication time was 13.2 years. The productivity level is focused on articles with an average number of authors of just 2.06 per article. The Bradford core was formed by two journals, Optometry and Vision Science and Eye and Contact Lens. ConclusionsResearch on multifocal contact lenses has exponential growth, without evidence of having reached a saturation point. The main countries in scientific production in this field are the United States and Australia.

CONTROLLING MYOPIA PROGRESSION IN CHILDREN

Main aim of this article was a systematic review on causes and management of Myopia progression in children. Myopia is a general disorder, affecting just about one-third of the US popula­tion and over 90% of the population in some East Asian countries. Elevated amounts of myopia are connected with a bigger risk of sight-threatening troubles, such as retinal detachment, choroidal degeneration, cataracts and glaucoma. Slowing the progression of myopia could potentially advantage millions of children in the India. Few approaches used for myopia organize have proven to be useful. Treatment options such as undercorrection of myopia, gas permeable contact lenses, and bifocal or multifocal spectacles have all been proven to be inef­fective for myopia control, although one recent randomized clinical trial using executive top bifocal spectacles on children with progressive myopia has shown to decrease the progression to nearly half of the control subjects. The most effective methods are the use of orthokeratology contact lenses, soft bifocal contact lenses, and pharmaceutical agents such as atropine, timolol or pirenzepine.&#x0D; Keyword: Myopia progression, pharmaceutical agents, lenses, treatment.

Bifocal and Multifocal Contact Lenses for Presbyopia and Myopia Control.

Bifocal and multifocal optical devices are intended to get images into focus from objects placed at different distances from the observer. Spectacles, contact lenses, and intraocular lenses can meet the requirements to provide such a solution. Contact lenses provide unique characteristics as a platform for implementing bifocality and multifocality. Compared to spectacles, they are closer to the eye, providing a wider field of view, less distortion, and their use is more consistent as they are not so easily removed along the day. In addition, contact lenses are also minimally invasive, can be easily exchangeable, and, therefore, suitable for conditions in which surgical procedures are not indicated. Contact lenses can remain centered with the eye despite eye movements, providing the possibility for simultaneous imaging from different object distances. The main current indications for bifocal and multifocal contact lenses include presbyopia correction in adult population and myopia control in children. Considering the large numbers of potential candidates for optical correction of presbyopia and the demographic trends in myopia, the potential impact of contact lenses for presbyopia and myopia applications is undoubtedly tremendous. However, the ocular characteristics and expectations vary significantly between young and older candidates and impose different challenges in fitting bifocal and multifocal contact lenses for the correction of presbyopia and myopia control. This review presents the recent developments in material platforms, optical designs, simulated visual performance, and the clinical performance assessment of bifocal and multifocal contact lenses for presbyopia correction and/or myopia progression control.