BS - Myopia (Nurture) - Week 10 Flashcards
Name 5 environmental conditions associated with a higher prevalence of myopia.
Higher education and income levels Professional or office-related occupations Better housing Increased near work Reduced outdoor activities
How do birth parameters (weight and length) affect myopia prevalence?
Mixed results, still unclear <2,500g - shorter mean AL >4kg longer AL Birth length weakly associated with AL However, hyperopia is also positively correlated with birth weight in preterms
Does parental smoking affect myopia prevalence?
Yes, studies suggest it lowers myopia prevalence.
What effect does lid fusion have on axial length (dark and light)?
Neonatal lid fusion in macaque monkeys caused elongation of the eye when maintained in an illuminated environment.
In the dark, it had no effect.
Does congenital cataracts influence myopia prevalence?
Yes, congenital cataracts is assoicated with a longer axial length.
Does congenital ptosis influence myopia prevalence?
Yes, more ptosis means more myopia
Where is the region/population of greatest myopia prevalence?
Younger generations of Inuit Eskimos
Is there a difference between urban and rural prevalence of myopia?
Urban prevalence is higher
How does reading time and working distance affect myopia risk?
Reading >30 mins duration - 1.5x higher risk
Reading <30cm working distance - 2.5x
Which of the following changes in individuals with progressing myopia? Corneal curvature Anterior chamber depth Lens thickness Vitreous chamber depth
Vitreous chamber depth
Is there an association between myopia risk and time spent outdoors, or is it a weak link? Can spending time outdoors be protective against myopia?
There is an association.
It can be protective, especially for children 11-20 yoa.
Is there an association between myopia and indoor sport?
No
Which has a greater effect on myopia risk, outdoor time or near work time?
Outdoor time
How are myopes typically for physical activity and time reading?
Less physically active, more time reading
How many hours of physical activity per day will offset how many hours of study per day?
1h of physical activity offsets 3h of study time per day.
Is outdoor activity protective against myopia for children under 7 yoa?
Yes
Is physical activity correlated with myopia? Explain in terms of standard deviations.
Children 1sd below average physical activity times were 10% more likely to have myopia.
Are there studies showing no association between outdoor activity and myopia?
Yes, but more show an association
What is important about outdoor viewing distances for myopia (2)?
Low level accommodative demand
Flat dioptric topographies
Is myopia seasonal?
No strong evidence, but reported to be less in summer by 0.10-0.20D
Name 5 possible reasons why better light may impact myopia risk.
Pupil constriction Less accommodation errors Better quality retinal image Dopamine release Spectral composition
What effect does a dopamine antagonist have concerning myopia?
It blocks the protective effects of high light levels.
Consider monkeys that are maintained in high light levels. How does this affect myopia prevalence?
87% reduction in myopia.
Name 12 environmental factors suspected to play a role in myopia risk.
Nutrition Birth parameters Stature Outdoor exposure Light levels Physical activity Vitamin D Near work Education Occupation