Lesson in Biological Psychology

1. Vision Impairments
Prepared by:
Orlando A. Pistan, MAEd
Psychology Instructor

2. Vision Impairments
Vision impairment is defined as
a limitation of one or more
functions of the eye
or visual system.
The most common vision
impairments affect the:
1. sharpness or clarity
of vision (visual acuity)
2. normal range of what you
can see (visual fields)

3. Vision Acuity Chart
A Snellen chart is an eye
chart that can be used to
measure visual acuity.
Snellen charts are named
after the Dutch
ophthalmologist Herman
Snellen, who developed the
chart in 1862.

4. Causes:
Globally, the leading causes of
vision impairment are:
 Refractive errors
 Cataract
 Macular degeneration
 Glaucoma
 Diabetic retinopathy
 Corneal opacity
 Trachoma

5. Refractive Errors
A refractive error is a very
common eye disorder. It occurs
when the eye cannot clearly
focus the images from the
outside world.
The result of refractive errors is
blurred vision, which is
sometimes so severe that it
causes visual impairment.

6. Hyperopia and Myopia

7. Astigmatism
A defect in the cornea or in the lens of the eye caused by a deviation from
spherical curvature, which results in distorted images, as light rays are
prevented from meeting at a common focus.

8. Cataract
A cataract is a clouding of the lens in
the eye which leads to a decrease in
vision. Cataracts often develop slowly
and can affect one or both eyes.
Symptoms may include faded colors,
blurry or double vision, halos around
light, trouble with bright lights, and
trouble seeing at night.
It is a result of ageing, metabolic
disorder trauma and heredity.
Surgery is the only
effective treatment. Surgery involves
removing the cloudy lens and
replacing it with an artificial lens.

9. Macular Degeneration
A degenerative condition affecting
the central part of the retina (the
macula) and resulting in
distortion or loss of central vision.
It occurs especially in older adults,
in which case it is called age-
related macular degeneration
The most common and effective
clinical treatment for Age-
related Macular Degeneration is
anti-VEGF therapy – which is
periodic intravitreal (into the eye)
injection of a chemical called an
“anti-VEGF.”

10. Glaucoma
Glaucoma is a condition that causes
damage to your eye's optic nerve and
gets worse over time.
The increased pressure, called
intraocular pressure, can damage the
optic nerve, which transmits images
to your brain. If the damage
continues, glaucoma can lead to
permanent vision loss.
In general, glaucoma cannot be cured,
but it can be controlled. Eye drops,
pills, laser procedures, and surgical
operations are used to prevent or
slow further damage from occurring.

11. The aqueous humour plays an essential role in the health of your eye.
As well as nourishing the cornea and the lens by
supplying nutrition such as amino acids and glucose.

12. Diabetic Retinopathy
It's caused by damage to the blood
vessels of the light-sensitive tissue at
the back of the eye (retina).
Characterized by
 Swelling, blood or fatty deposits in
the retina
 Growth of new blood vessels and
scar tissue
 Bleeding in the clear, jelly-like
substance that fills the center of
the eye (vitreous)

13. Diabetic Retinopathy
 Photocoagulation. This laser treatment
can stop or slow the leakage of blood and
fluid in the eye.
 Panretinal photocoagulation. This laser
treatment can shrink the abnormal blood
vessels.
 Vitrectomy. This procedure uses a tiny
incision in your eye to remove blood from
the middle of the eye (vitreous) as well as
scar tissue that's tugging on the retina.
 Vascular endothelial growth factor
(VEGF) inhibitors, may help stop growth of
new blood vessels by blocking the effects of
growth signals the body sends to generate
new blood vessels.
 Surgery often slows or stops the
progression of diabetic retinopathy, but it's
not a cure. Because diabetes is a lifelong
condition, future retinal damage and vision
loss are still possible.

14. Corneal Opacity
Corneal opacity is a disorder of
the cornea. The cornea is the
transparent structure on the front of
the eyeball. Corneal opacity occurs
when the cornea losses its
transparency and becomes scarred.
This stops light from passing through
the cornea to the retina.
 Antibiotic, antibacterial, antifungal,
or steroidal eye drops.
 Topical or oral antiviral
medication.
 Phototherapeutic keratectomy
(laser surgery)
 Corneal transplant.

15. Trachoma
Trachoma is an infectious disease
caused by bacterium Chlamydia
trachomatis. The infection causes a
roughening of the inner surface of the
eyelids. This roughening can lead to
pain in the eyes, breakdown of the
outer surface or cornea of the eyes,
and eventual blindness.
Untreated,
repeated trachoma infections can
result in a form of permanent
blindness when the eyelids turn
inward.
Treatment with antibiotics alone
may be enough to eliminate the
infection

16. Eye Specialists
Ophthalmologist – is a medical doctor (MD), they are trained to
perform eye examinations, diagnose and treat disease, prescribe
medications, and perform eye surgery. They also write
prescriptions for eyeglasses and contact lenses.
Optometrist – Doctor of Optometry (OD), examines eye for both
vision and health problems. They correct refractive errors by
prescribing eyeglasses and contact lenses.

17. Vision Impairments
Thank you for paying
attention.