Myopia Flashcards
Etiology of Myopia:
- Elongated Axial length
- Refractive system is too strong for its axial length
- Increased depth of anterior chamber
- Cataract formation
- Diabetes mellitus
Classifications of Myopia:
- According to amount
- According to Sorsby
- By Origin
- Onset and Course
- Form of Categories
low degree myopia:
-0.25D to -3.00D
medium degree myopia:
-3.00 to -6.00D
High degree myopia:
-6.25D and above
Sorsby correlative type myopia:
if the refractive power is -6.00D and below
Sorsby component type myopia:
if the refractive power is more than -6.00D
simple, benign, stationary myopia
Correlative Myopia
mildy progressive
if progressing, occurs during the years of growth
customary type myopia
pathological, progressive, malignant, degenerative myopia
Component Type
due to an abnormal development of the components of the ocular refractive mechanism on the malignant effect of one or more components of diseases
Component type myopia
Onset and Course classifications of myopia:
- Stationary Myopia
- Temporarily progressive
- Permanently progressive
Forms of Categories of myopia:
a. Simple Myopia
b. Degenerative myopia
Signs and Symptoms of Myopia:
- Dilated pupils
- Squinting of Eyes
- Staring expression
- Exophthalmos (high myopia)
- Myopic crescent (under ophthalmoscope)
Prevalence of Congenital myopia:
1 - 2%
Prevalence of Early Onset myopia (6 - 15 yrs old)
15 - 30%
Prevalence of Late onset myopia (above 18 yrs old):
8 - 10%
Prevalence below -6.00 D in sex/gender:
20% more common in males
Prevalence above -6.00D in sex/gender:
twice as common in females
Highest myopia prevalence in Race:
Chinese and Japanese
a condition of tonic spasm of accommodation which frequently an emmetrope or hyperope appears to be myopic
Pseudomyopia
myopia that is revealed by inconsistencies between objective and subjective testing procedures
anomalies of convergence, by spasmodic results in subjective routing and by history of the patient
Pseudomyopia
Other names of Pseudomyopia:
- School myopia
- College myopia
- False myopia
- Refractive myopia
- Functional Myopia
the amount of myopia that usually appear in dim illumination
Night myopia / Nocturnal Myopia
Uncorrected myopia is less noticeable during ______
daytime
Symptoms of Night myopia:
- BOV only in low luminance
- feeling of discomfort maintaining fixation in low illumination
- difficulty in night driving and halos around light
Causes of Night myopia:
- Spherical Aberration
- Chromatic Aberration
- Purkinje shift
- Error in Accommodation occurring in dim light
Causes of Night myopia:
- Spherical Aberration
- Chromatic Aberration
- Purkinje shift
- Error in Accommodation occurring in dim light
it is when corneal curvature is becoming irregular or increasing in curvature which results to an increase in the error of refraction resulting to myopia
Keratoconus
disorders causing Keratoconus:
- Down syndrome
- Ehlers Danlos Syndrome
Rate of progression of Myopia:
-0.25 to 0.55D per year until teen years
Earlier onset of myopia means:
faster progression
Greater Myopia
Myopia control / management lenses:
- Myopilux
- MiyoSmart
- Vision therapy lens
