L3 Flashcards
(19 cards)
What is refractive error?
A failure of the eye to focus images sharply on the retina, causing blurred vision.
What is emmetropia?
The state of refraction where parallel rays of light are focused exactly on the retina without accommodation.
What is ametropia?
Any deviation from emmetropia; includes myopia, hyperopia, and astigmatism.
What is myopia?
A condition where parallel rays of light focus in front of the retina when accommodation is relaxed.
What is hyperopia?
A condition where parallel rays of light focus behind the retina when accommodation is relaxed.
What is the difference between axial and refractive ametropia?
Axial ametropia is due to abnormal length of the eyeball; refractive ametropia is due to abnormal refractive power of the eye’s components.
What are the two main causes of myopia?
Excessive axial length or increased curvature of the cornea/lens.
What are the two main causes of hyperopia?
Short axial length or decreased curvature of the cornea/lens.
What is the far point of the eye?
The point in space from which an object must be placed so its image is focused on the retina with accommodation relaxed.
Where is the far point in myopia?
In front of the eye (finite distance).
Where is the far point in hyperopia?
Behind the eye (virtual point).
What is the near point of the eye?
The closest point at which an object can be seen clearly with maximum accommodation.
What is presbyopia?
Age-related loss of accommodation, resulting in difficulty focusing on near objects.
What is the main clinical symptom of uncorrected refractive error?
Blurred vision.
What is the pinhole test and what does it indicate?
A test using a pinhole occluder to improve vision in refractive error; improvement suggests refractive cause of reduced acuity.
What is the clinical significance of the red reflex?
It helps to detect media opacities such as cataract.
What are some signs of uncorrected myopia in children?
Squinting, sitting close to the TV/board, holding books close.
What are some signs of uncorrected hyperopia in children?
Eye strain, headaches, avoidance of near tasks.
What is the importance of early detection of refractive error?
Prevents amblyopia and supports normal visual development.
