MIDTERMS Flashcards
(38 cards)
Classification of Functional Vision Deficits
- Cloudy media
- Central Field Deficit
- Peripheral Field Deficit
no field deficit (overall blur)
Cloudy media
Any condition that alters the clarity of several clear structures may result in overall blurred
or hazy vision, impaired detail vision or significant glare without a field deficit
Cloudy Media
Functional Implications of Symptoms:
o Generalized hazy or blurred vision
o Lost of ability to perceive sharp details
o Printed materials appeared faded, as do colors
o Focal opacities sometimes cause monocular diplopia
o Sunlight and direct lighting tend to cause glare
o Contrast is usually reduced causing poor border detection of both small and large
objects
directly related to the extent of disorder, often 20/200 or worse
Visual Acuity
blurred
Amsler Grid
strong positive
Glare Test
loss at all frequencies
Contrast Sensitivity
Functional Tests Results
Visual Acuity –
Amsler Grid
Glare Test –
Contrast Sensitivity
Management of Cloudy Media
Careful refraction which may involve automated refraction and keratometry. Visual
acuity with pinhole and/or refraction over a bandage contact lens can neutralize tear
film abnormalities, focal, opacities or irregular corneal surface.
- Moderate increase light can help patients with reduced contrast to perform better,
especially with proper positioning to avoid glare
use of the following is advisable:
o Sun visor or hat
o Typoscope
o CCTV
o Sunglasses
o UV filters
o Polarizing filters
o Anti-reflective coating
General measures to improve contrast are helpful like:
o Yellow filters or amber glasses
o CCTV with variable contrast
o Large print books
o Felt-tipped markers
Improving contrast almost always helps. Measures include enhancing print contrast
through large print and with dark, felt-tipped markers, along with yellow filters indoors and
plum (light or medium) outdoors. CCTV provides a range of magnification along with
improved contrast
Central Field Deficit
Certain diseases preferentially affect the peripheral retina or nerve pathways that carry
information from the peripheral visual field. The functional implications indicate mobility
and night vision affections.
- Peripheral field defects causing functional deficits generally fall into two categories: the
general constriction and the sector or hemianopic field defect.
Peripheral Field Deficit
Functional Implication of Symptoms Peripheral Field Deficit
o Performance of the peripheral retina worsens at night or under poor illumination
o Patients may be unable to perceive people or objects in the surroundings unless the
object appears in their remaining visual field
o Difficulty ambulating in unfamiliar environment and anxiety about bumping into
peripheral objects.
o Difficulty in locating objects
– usually good if there is no macular disease or cataract, may be 20/20
Visual Acuity
normal if there is no macular disease, periphery is missing if field
constriction is advanced
Amsler Grid
negative unless media pathology co-exists
Glare Test
usually normal (except glaucoma) but may be difficult to test if
the central field is less than 5 degrees.
Contrast Sensitivity
reduced
Visual Field
allows you to predict the add from the best corrected distance acuity
Kestenbaum’s Rule
allows you to read the predicted add directly from the near visual acuity chart.
Lighthouse Method
predicts an add based on both the patient’s best-corrected distance
acuity level and the actual desired near acuity level.
Reciprocal Vision
Consider the primary goal of the patient particularly the tasks and history
Deciding on Style
