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Myopia progression

The document discusses myopia progression, highlighting that it is a refractive error where parallel rays focus in front of the retina, with various factors influencing its development including age, gender, genetics, and environmental conditions such as near work. It also covers theories of myopia progression and control measures including modifications in environment, use of specialized spectacles or contact lenses, and pharmacological therapies. The document emphasizes the importance of understanding the underlying mechanisms and risk factors for effective management of myopia.

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MYOPIA PROGRESSION • By Optom Pratiksha Patil & • Optom Samiksha Prajapati • M. Optom 1st Year
MYOPIA • It is a type of refractive error in which the parallel rays coming from infinity comes to focus in front of the retina, when accommodation is at rest. • Total eye power is greater than 60 D
FACTORS EFFECTING MYOPIA • Age • Gender • Genetic factors • Ethnicity • Environment and work related :Near work (Reading, High literacy, accommodation) • Race • Under correction
AGE • Congenital Myopia • Youth-onset Myopia • Early adult-onset Myopia • Late adult-onset Myopia BORISH CLINICAL REFRACTION Arch Ophthalmol. 2005;123(7):977-987. doi:10.1001/archopht.123.7.977
GENDER • Progression of myopia tends to begin and end early in Females. Arch Ophthalmol. 2005;123(7):977-987. doi:10.1001/archopht.123.7.977
GENETIC FACTORS • 39 genetic loci have been identified in the human genome which may be associated with refractive error and myopia. • The Sydney Myopia study found that the influence of one myopic parent was double the risk of myopia while having two myopic parents increased that risk by eight times. https://www.opticianonline.net/cet-archive/184 (myopia part-1)
ETHNICITY • High prevalence in Asian, Caucasians and Hispanic • Lower prevalence in White and African-Americans • Urban Vs Rural Population Myopia is more common in urban community than in rural community Arch Ophthalmol. 2005;123(7):977-987. doi:10.1001/archopht.123.7.977 • BORISH CLINICAL REFRACTION
ENVIRONMENT AND WORK RELATED • Evidence for a link between near work and myopia progression continues to be reported in a wide range of populations. • Parssinen has shown that near work and short reading distance are significantly corelated to increased myopia progression. • The Beijing eye pediatric eye study conducted in 15066 school children with mean age 13.2 +/- 3.4 years. This study reported that long reading duration, shorter distance watching TV or computer, dim reading illumination are significantly associated with myopia. http://commons.pacificu.edu/opt
RACE
http://commons.pacificu.edu/opt
UNDER-CORRECTION • Under correction of myopia produce myopic defocus during distance viewing has been reported to produce an increase instead of a decrease in myopia progression.
SEASONAL VARIATION • More progression in winter ( December to March) • Lesser progression in summer (June to September)
THEORIES AND PROGRESSION
• Theories and Progression • Accommodation, IOP and Axial elongation • Accommodative Lag Theory • Mechanical tension Theory ( Role of Ciliary body and Choroid) • Concept of Emmetropization at Near • Role of EOM • The Selection-Relaxation theory • The effect of Blur • Peripheral refraction
• Most commonly accepted theories used to explain how myopia progresses:
• Lag of Accommodation • High lag of accommodation during near work causes foveal hyperopic retinal blur • Induces an abnormal axial growth of the eye leading to myopia • Myopes have a reduced accommodative response compared to emmetropes • Treat myopic children with plus lenses for near work • e.g. Bifocals and Progressive Addition Spectacles
• Mechanical Tension • Eye responds to transient changes in axial length following short periods of accommodation • Contraction of the ciliary muscle following accommodation results in forward and inward pulling of the choroid • Ciliary-choroidal tension restricts the equatorial growth of the eye • It decreases the circumference of the sclera leading to a more prolate eye shape and ultimately to an elongation of the axial length
Schematic representation of the mechanical tension theory
• Peripheral Refraction • Peripheral hyperopic defocus has been suggested to play a significant role in development of myopia • Several meta-analyses reported a significant reduction of myopia progression with treatments that reduce peripheral hyperopic defocus (i.e. orthokeratology and centre- distance multifocal soft contact lenses)
Schematic representation of the peripheral theory
HOW TO CONTROL MYOPIA???
• Myopia can be controlled by following measures: 1. Environmental Modification 2. Spectacles and Contact lenses 3. Pharmacological Therapies
1. Environmental Modification • Outdoor Activity • Cocoa • Use of amber filters
2. Spectacles and Contact lenses • Bifocal and Multi-focal glasses and contact lenses • Ortho-K lenses
3. Pharmacological Therapies • Anti-muscarine agents (Atropine 0.01%, Pirenzepine) • Dopamine – by preventing myopic shift
• In rabbits injection of dopamine prevented the myopic shift and vitreous chamber and axial elongation typically associated with form deprivation myopia ( ref. Gao Q et al 2006 )
REFERENCE • Myopia (3rd chapter) Primary Care Optometry • Borish’s Clinical Refraction pg.no. 1443 • Study of theory about myopia progression (STAMP) vol-87, optom & Vn Science • https://www.researchgate.net/publication/317762239_Theories_Behind_Myopia_Pro gression • http://commons.pacificu.edu/opt/14 • (https://www.brienholdenvision.org/privacystatement) • Arch Ophthalmol. 2005;123(7):977-987. doi:10.1001/archopht.123.7.977 • https://www.opticianonline.net/cet-archive/184 (myopia part-1)
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