PSY 4036 Week 4: Visual-Field Loss
Week 4: Visual-Field Loss
Structure and measurement of the visual field.
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Patterns of visual-field loss.
Glaucoma, retinitis pigmentosa and hemianopia.
Cortical visual impairment (CVI)
Three Dimensions of Vision
Measurement and Loss
Low vision is usually discussed in terms of:
Reduced acuity
Reduced contrast sensitivity
Visual-field loss.
Demo of Lighthouse Distance Acuity Chart [Position student at 4 m to demonstrate designation of viewing distance, and point out the various lines on the chart as I discuss them.]
The Normal Visual Field
Common Patterns of Field Loss
Tangent Screen
Humphrey Visual Field Maps
Common Patterns of Field Loss
Vision with Field Loss
from Glaucoma
Normal vision
Vision with advanced glaucoma
Common Patterns of Field Loss
US Causes of Childhood VI
Diagnosis Causes of vision loss in students from the schools for blind in the US in 2012 (% of total)
Cortical visual impairment (CVI) 18
Optic nerve hypoplasia 15
Retinopathy of Prematurity (ROP) 14
Optic Atrophy 7
Albinism 4
Coloboma 3
Glaucoma 3
Retinal detachment, non ROP 2
Leber congenital amaurosis 2
Retinitis pigmentosa 2
Microphthalmia/Anophthalmia 2
Cataract 2
Nystagmus 2
Other or unknown 24
Based off of Table 3, Kong et al 2012
Some Terminology Related to CVI
Ocular vision impairment and cortical visual impairment
Cerebral visual impairment.
Cortical blindness
Causes of CVI
Periventricular Leukomalacia (PVL) white matter disorder common in extremely premature infants.
Hypoxic ischemic encephalopathy (HIE). Associated with asphyxia during difficult birth.
Infections, such as encephalitis.
Traumatic brain injury from abuse or accidental injury.
Others including hemorrhage or stroke.
Ten Visual & Behavioral Characteristics of CVI
Color preference. Strong preference for a particular bright color such as red or yellow.
Attraction to movement. Captivated by moving objects such as a ceiling fan, TV action, or staring out of the window of a moving car.
Visual latency. Slow visual response to the appearance of a new object in the scene.
Visual field preferences. Often a preference for non-central vision. May turn the head to use a particular portion of the peripheral visual field to look at things. Lower visual field is often impaired, impacting mobility.
Difficulty with visual complexity. Simple patterns, such as objects with a single color, are recognized better than multi-colored surfaces or objects in cluttered scenes. Difficulty integrating multi-sensory input such as combined audiovisual stimuli. Difficulty recognizing faces and making eye contact.
Need for light. Gazing at bright lights is common as well as attraction to shiny surfaces.
Ten Visual & Behavioral Characteristics of CVI Continued…
Difficulty with distance viewing. Distant objects are harder to attend to and recognize, possibly because of confusion with background clutter. A single object held close to the face may be easier to attend to.
Atypical visual reflexes. Delayed or absent blink response when touched on the bridge of the nose. Absent or delayed blink response to an object rapidly approaching the face along the midline.
Difficulty with visual novelty. Unlike typical infants who prefer to look at novel stimuli, those with CVI prefer familiar targets.
Absence of visually-guided reach. Failure to spontaneously reach for and touch nearby objects.
Adapted from Roman-Lantzy (2018, Chapter 3).
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