Refractive errors Flashcards
What is myopia? How is the anatomy of the eye different?
- Short sited (trouble with distant vision)
- Longer eye or lens is curved
How is myopia corrected?
Concave lens
What are the risks of myopia?
- Retinal detachment
- Open angle glaucoma
- ARMD
What is hypermetropia? How is the anatomy of the eye different?
- Long sited (trouble with near vision)
- The eye is shorter or the lens flatter
How is hypermetropia corrected?
Convex lens
What are the risks of hypermetropia?
Acute closed angle glaucoma
What is presbyopia and why does it happen?
Inability to accommodate seen in older people due to reduced elasticity of the lens meaning it can’t become thicker to accommodate
How is presbyopia corrected?
Convex lens
Bifocals if pre-existing refractive errors
What is an astigmatism?
The eye is normally a sphere however in astigmatism there are 2 axis of curvature to the eye giving 2 foci on the retina
What is ambylopia?
Reduced vision due to reduced processing of visual information
Describe the pathophysiology of amblyopia
- condition such as squint, cataract, anisometropia, retinoblastoma
- there are conflicting images on the retina
- the brain turns off binocular processing to allow a single visual input
- the development of the neuro-retina halts resulting in decreased vision
What is the crowding phenomenon?
In amblyopia the vision is worse when letters are crowded together
How can amblyopia be managed?
Patching or dilating drops in to the good eye
What is anisometropia?
Unequal refractive errors
If a person has - vision what does this mean?
If a person has + vision what does this mean?
- means they are a myope
+ means they are a hypermetrope
