Retinoscopy/Refraction Flashcards
What is static retinoscopy?
Control for accommodation (cycloplegia, fog, distance fixation)
What is dynamic retinoscopy?
Does not control accommodation, often used to determine the near Rx
How can you perform infant retinoscopy?
Loose lenses or skiascopy, cyclopligia, finger puppet or light for target
Why and how is cycloplegia used in infant ret?
Preferred due to the robustness of accommodative response and small pupil size, infants use 0.5% cyclopentolate (1% tropicamide 2nd choice), 12 months + 1% cyclopentolate
What is Mohindra near ret?
Technique for assessment of distance refractive error, has good correlation with cycloplegic results
What is the Mohindra technique?
Dark room, infant fixates on ret light at 50 cm, determine magnitude of with/against with skiascopy bars, then subtract 1.25 D from result
What techniques are used for toddler/preschool ret?
Loose lenses or skiascopy bars
How is toddler/preschool ret performed?
Movie as fixation target, ret and trial frame the results
When is cycloplegia indicated for toddlers/preschoolers?
Decreased VA, esotropia, high hyperopia or a variable reflex
What cycloplegia is used of toddler/preschooler?
Cyclopentolate 1% is a wet refraction (tropicamide 1% is damp because not full cycloplegia)
At what age can a child sit in the phoropter?
8+
What is the indication for cycloplegia in school aged ret?
Decreased VA, esotropia, variable reflex
Can school aged children understand JCC?
Normally yes
What is the average refractive error of full term newborns?
+2.00, 88% between Plano and +4
What is the standard deviation for refractive error of full term newborns?
2.00 +/_ 2.75
What percent of full term newborns have astigmatism?
30%
What is emmetropization?
Tendency for the refractive state of the eye to change close to plano, converges to low hyperopia
What is the standard deviation after emmetropization?
+0.50 to -1.00 +/- 1.00
Theories of active emmetropization?
Regulated by retinal image- eye interprets retinal blur and adjusts, sustained near vision and myopia, animal studies make functional myopia/hyperopia, eye is growing/increase axial length
What is the evidence for emmetropization regulated by retinal image?
Media opacities ROP, myopia more common
What is the “evidence” for sustained near vision and myopia?
Law students/jewelers
What are theories of passive emmetropization?
Physical changes- refractive errors move to emmetropia initially, genetics affect Rx, changes in corneal/lenticular power
How do genetics contribute to passive emmetropization?
If both parents are myopic you have a 42% chance, if one is you have a 22.5% change, if neither is you have an 8% chance
What could changes in corneal/lenticular power be in response to?
Increase axial length, creates balance for emmetropization
What are the structural changes of emmetropization?
Crystalline lens adds layers, increase net weight, and flattens; corneal power decrease, axial growth occurs
What does the BIBS study stand for and when was it conducted?
Berkeley Infant Biometry Study 2009
How many infants participated in the BIBS study and at what ages?
262 infants, ages 3, 9, and 18 months
What was the body weight for the BIBS study?
> 2500 g
What test did BIBS conduct?
Cycloplegic, near and Mohindra ret, visual acuity
What did the BIBS study find?
bidirectional emmetropization
What was the best predictor in the BIBS study?
Cycloplegic refraction
Higher magnitude = _____ likely to be emmetropized at 18 months
Less
T/F large amounts of astigmatism are common in children < 3 years old
True, +1 D in 30% of newborns
Which is more common in <3 years old, WTR or ATR?
ATR
When is astigmatism highest and when does it reach adult levels?
Highest in the first two years, adult levels by age 4-5
T/F if little astigmatism in 1st year of life, not likely to acquire
True
What is MEPEDS and when was it?
Multi Ethnic Pediatric Eye Disease Study 2011
What did MEPEDS look at?
Astigmatism in children ages 6-72 months
What did MEPEDS find?
> 1.50 D astigmatism in 16.8% of Hispanic children and 12.7% AA; >3.00 D astigmatism in 2.9% of Hispanic and 1% AA
T/F the majority of the astigmatism found in MEPEDS was WTR and decreased with age
True
What percent of preschoolers failed an exam two times in LA?
18%
How many preschoolers had vision screenings in LA?
56%
What percent of preschoolers in LA had myopia >-0.50 D?
20%
What percent of preschoolers in LA had hyperopia >+0.50 D?
59%
What percent of preschoolers had astigmatism > -1.50D in LA?
66%
Which ethnicity was the least hyperopia and which was the most?
Least-Asian, most-white
Which ethnicity had the most astigmatism?
Latino (68%) AA (61%)
Most children starting school (5-7 years old) have ____ refractive error
+0.50 to +3.00 refractive error
When is the lowest prevalence of myopia?
5-7 years old
T/F 5-6 year olds with plano to +0.25 D are likely to become myopic by teenage years
True
Do girls or boys become myopic faster?
Girls
T/F refractive error changes faster in children with myopia than hyperopia
True
