UNIT 3: Epidemiology Flashcards

1
Q

Epidemiology

A

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.

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2
Q

When refracting a hyperope,

A

We must FOG or use cycloplegics.

Otherwise, the habitual use of accommodation causes spasmadic action of the ciliary body. (Could cause pseudo-myopia)

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3
Q

Classification of Hyperopia (Total)

A

Manifest +Latent Hyperopia

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4
Q

Classification of Hyperopia (Latent)

A

(Patient in accommodation Spasm) —> Not revelaed by normal refraction

This spasm could be fixed or temporary

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5
Q

Classification of Hyperopia (Manifest)

A

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

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6
Q

Correction By Age (Hyperopia) Up to 6

A

-Correct if strabismus
-Lower VA or Asthenopia

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7
Q

Correction By Age (Hyperopia) 6 to teens

A

-Correct is asthenopic
-Find more latency at this age
-Under correct slightly
(SUBS. They cant take what they need OBJ.)

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8
Q

Correction By Age (Hyperopia) Adult

A

-Full error revealed and corrected
-Caution in full new RX –> must re-adjust
conv, acc systems - may need VT

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9
Q

Correction By Age (Hyperopia) Presbyopia

A

-May up distance due to the change of index of lens nucleus
-Will also find latents at this time

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10
Q

Correction By Age (Hyperopia) Old Age

A

-May up myopia (due to lens change)

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11
Q

Classification (Astigmatism) Total

A

1) Anterior Corneal
2) Residual
a)Posterior corneal
b)Lenticular Surface

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12
Q

Classification (Astigmatism) Corneal

A

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

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13
Q

Classification (Astigmatism) Lenticular

A

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

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14
Q

Lowest incidence of Myopia

A

-Spain (Portugal, P.R,. Filipino)
-Hawaii
-Africa

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15
Q

Highest incidence of Myopia

A

-China
-Parts of the U.S.

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16
Q

Classification of myopia

A

a) Very low 0.00 to -1.99D
b) Low -1.00 to -3.00D
c) Medium -3.00 to -6.00D
d) High -6.00 to -10.00D
e) Very High > -10.00D

17
Q

Objective indications for Myopia

A

-Squinting (“Crow-feet horizontal wrinkles)
-Dilated pupils
-Exophthalmos

18
Q

Pseudomyopia

A

-Condition of an on-going spasm of accommodation
-Hyperope or emmetrope becomes falsely myopic
-Other names:
-School myopia
-Functional myopia
-False myopia
-Refractive Myopia

19
Q

Corrections for Pseudomyopia

A

-Requires a PLUS lens
a) Fogging lenses = Strong plus for constant
wear for relaxing acc. Dist & Near.
b) Near Point Correction ( Plus for near )
c) Prism Base In = to relieve convergence from
the work of overcoming excessive exophoria & relieve acc/conv. Function
d) Visual Training

20
Q

Attempts to control myopia

A
  • Prism BI (often used during VT)
  • Visual Training = to relax accommodation
  • Hormones and diet (no good studies)
  • Contact lenses ( PMMA fit flatter than flattest
    K) (Orthokerotology)
  • Bifocals = relaxes acc/conv.
    -RK (radial keratotomy), PRK (photorefractive keratectomy)
21
Q

Congenital myopia

A

present at birth

22
Q

Acquired myopia

A

A result of prolonged stress on the eyes during close work

23
Q

Classification of hyperopia by degree

A

1) Low 0 - +3.00D = Normal vision
2) Medium +3.00 - 5.00D = Subnormal vision
3) High > 5.00D (subnormal at early age, then ->
Pathological)
- Micro ophthalmus
- Optic edemas
- Tumors

24
Q

TRUE OR FALSE
People with a certain amount of astigmatism in a specific location tend to remain stable.

A

TRUE
- Astigmatism rarely changes

25
Q

TRUE OR FALSE
Once people become presbyopic, they tend to have a standard decrease in add power dependent upon their age and near-visual requirements.

A

FALSE
- There is a standard INCREASE in add power.
- Add power have a definite pattern in
increasing amounts.

26
Q

FILL IN THE BLANK
Once people are declared Hyperopic, their degree of hyperopia doesn’t change greatly over the years. The only time they fall “ outside the norm” is when __________ ____________becomes _____________.

A

1) LATENT HYPEROPIA
2) MANIFEST

  • Hyperopia is usually stable and predictable.
27
Q

FILL IN THE BLANK
Of all the refractive errors, ________ is the only one to show ___________ _____________ factors on the incidence, distribution, degree and changes in Myopia.

A

1) MYOPIA
2) DEFINITE ENVIRONMENTAL

  • Myopia can be altered due to behavioral/
    Environmental factors, therefore is studied &
    analyzed a great deal.