Chapter 32: Vision Impairment Flashcards
Amplitude of accommodation
- How much accommodative (focusing) ability an individual has available.
- We can determine the minimum acceptable accommodation amplitude for any child using a formula: Accommodative amplitude = 15-1/4 (child’s age).
Refractive Errors
Astigmatism
Hyperopia
Myopia
Astigmatism (refractive errors)
The curvature of the front of the eye is elliptical, instead of spherical, and the result is blurred vision at both far and near.
Hyperopia (refractive errors)
- Farsighted
- A condition in which the length of the eye is too short and a child has clear vision when looking at a distance but requires more effort to achieve clear vision when reading
- Additional effort could cause eyestrain, blurred vision, and difficulty sustaining attention on a near task.
Myopia (refractive errors)
- Nearsighted
- A condition in which the length of the eye is too long and a child has clear vision when reading but blurred vision when looking at a distance.
Near point of convergence
When the child reports single vision, we record the distance from the child’s eyes and record this as the near point of convergence recovery finding. The expected finding for any child is to be able to maintain single vision to a distance less than 6 cm from the eyes. So, the break should be less than 6 cm and the recovery less than 9 cm.
Pursuits (eye-movement)
- Eye movements enable the continuous clear vision of moving objects.
- This visual following reflex ideally produces eye movements that assure continuous foveal fixation of objects moving in space.
Saccades (eye movement)
- An eye movement in which a child looks from one stationary object to another.
- The ideal saccade is a single eye movement that rapidly reaches and abruptly stops at the target of interest.
Strabismus
Condition in which the eyes are misaligned. It occurs in about 3% to 5% of the general population and is often cosmetically obvious.
Non-Strabismic Binocular Vision Disorders
Deviation where the eyes have a tendency to turn in, out, or up but this tendency is controlled at all time
Convergence Insufficiency
- Most common non-strabismic binocular vision disorder that occupational therapists will encounter
- A condition in which the eyes tend to drift outward when being used for near work such as reading, while at a far distance the eyes work well together.
- One of the leading causes of eyestrain and discomfort.
Vision Therapy
- Has been a treatment option for binocular vision, accommodative, and eye movement disorders since the 1920s and 1930s
- “Orthoptics,” sometimes used interchangeably with vision therapy, was primarily developed as a treatment for strabismus and amblyopia.
Visual Integrity Issues
- Visual Acuity
- Refractive Error
- Eye Health
Visual Acuity (visual integrity)
The ability to see fine detail
Refractive Error (visual integrity)
The optical characteristics of the eye (myopia, hyperopia, astigmatism)
