UNIT 3: Epidemiology Flashcards
Epidemiology
The study of the distribution and determinants of health-related states and events in populations, and the application of this study to the control of health problems.
When refracting a hyperope,
We must FOG or use cycloplegics.
Otherwise, the habitual use of accommodation causes spasmadic action of the ciliary body. (Could cause pseudo-myopia)
Classification of Hyperopia (Total)
Manifest +Latent Hyperopia
Classification of Hyperopia (Latent)
(Patient in accommodation Spasm) —> Not revelaed by normal refraction
This spasm could be fixed or temporary
Classification of Hyperopia (Manifest)
Revealed by routine refraction (what actually turns up in phoropter)
-Symptoms: Asthenopia
-HA’s, Tearing, photophobia, nausea, general fatigue, avoids N.V. Tasks
-Objective Symptoms:
-Vertical brow wrinkles
-Convergent strabismus
-ESO
Correction By Age (Hyperopia) Up to 6
-Correct if strabismus
-Lower VA or Asthenopia
Correction By Age (Hyperopia) 6 to teens
-Correct is asthenopic
-Find more latency at this age
-Under correct slightly
(SUBS. They cant take what they need OBJ.)
Correction By Age (Hyperopia) Adult
-Full error revealed and corrected
-Caution in full new RX –> must re-adjust
conv, acc systems - may need VT
Correction By Age (Hyperopia) Presbyopia
-May up distance due to the change of index of lens nucleus
-Will also find latents at this time
Correction By Age (Hyperopia) Old Age
-May up myopia (due to lens change)
Classification (Astigmatism) Total
1) Anterior Corneal
2) Residual
a)Posterior corneal
b)Lenticular Surface
Classification (Astigmatism) Corneal
1) Regular: 2 principal meridians 90 degrees apart each meridian uniform
a) Referred to Each Cornea
1. WTR (direct)
-Curvature of greatest power –> Vertical
-Curvature of least power –> Horizontal
2. ATR (inverse)
-Curvature of greatest power
3.Oblique
2) Irregular: 2 principal meridians NOT 90 degree apart or curvature in any meridian not uniform
Classification (Astigmatism) Lenticular
1) Regular or irregular
2) Unequal curvature of surfaces or layers
Prevalence: Most widely spread refractive error –> approx. 80% of population
For low Astig: Spherical equivalent –> SPH + 1/2 cyl
Lowest incidence of Myopia
-Spain (Portugal, P.R,. Filipino)
-Hawaii
-Africa
Highest incidence of Myopia
-China
-Parts of the U.S.