Lecture 21 Flashcards
Which variables are most influential in the refractive status of the eye?
- corneal power
- crystalline lens power
- anterior chamber depth
- axial length of the eye
What is average corneal power?
43 D
What is average power of the crystalline lens?
20 D
what is average axial length of the eye?
24 mm
When does emmetropoization occur
at birth
what 3 things are a part of the near triad?
- accommodation (makes object clear)
- convergence (makes object single)
- meiosis (inc depth of focus)
what are categories for myopia
- simple myopia
- nocturnal myopia
- pseudomyopia
- degenerative (pathological) myopia
- induced (acquired) myopia
- degree (low, med, high)
- age of onset
what are risk factors for myopia
- family history of myopia
- presence of myopia of noncycloplegic ret in infancy, decreasing to emmetropia before entry to school.
- Refractive error of emmetropia to 0.50 D hyperopia in kids and young adults.
- ATR astigmatism
- Dec accommodative function/nearpoint esophoria
- Substantial amount of near work on a regular basis
- Steep corneal curvature or high axial length to corneal radius ratio.
- Conditions temporarily obscuring the retina from clear imagery during infancy.
what are the degrees of myopia
- low: < 3.00 D
- med: 3.00 - 6.00 D
- high: >6.00 D
_____ myopia is the most common form of myopia. It inc in severity during childhood, slows down during teenage years and decreases at about 45. It is usually inherited or due to near work.
Simple
_____ myopia occurs as an inc. accomm response associated with low levels of light. People with this type of myopia have blurred distance vision in dim illumination and have difficulty driving at night
Nocturnal
_____ is when patient appears to have myopia due to an inappropriate accommodative response more specifically, an overstimulation of accommodation and occurs more in younger patients who do a lot of near work. These patients have high _____. They have transient blurred vision after near work. They complain about asthenopia and have more minus power in manifest refraction than on cyclopegic refraction.
Psuedomyopia; exophoria
_____ myopia is due to degenerative changes in the _____ segment of the eye. It is usually inherited and there is interruption of light passing through ocular media. These patients have constant blur at distance and flashes of light or floaters and have A LOT of diseases or issues with their eye
degenerative; posterior
_____myopia is often temporary and is reversible. It is usually due to age related nuclear cataracts, exposure to _____and variability in their blood sugar level.
Induced; sulfanamides
What are the classifications of hyperopia
- physiologic (funtional) hyperopia
- pathologic hyperopia
- Structure
- Degree of refractive error
- Role of accommodation (facultative vs absolute hyperopia)
- Outcome of noncylcopegic and cyclogplegic refractions (manifest and latent hyperopia)
- Presence or absence of symptoms
