3-30-15 JSeino Opt 10 Lecture
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Transcript of 3-30-15 JSeino Opt 10 Lecture
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Jennifer Seino, O.D., F.A.A.O. School of Optometry
University of California, Berkeley
Cornea – Dome-shaped transparent tissue covering the front of
the eye; bends light to focus the image on or near the retina; about 2/3 of the focusing power of the eye
Crystalline lens – Transparent elastic structure behind the iris and pupil;
helps focus light with the cornea; about 1/3 of the focusing power of the eye; can also adjust it’s focusing power to focus on objects at different distances from far to near
Retina – Light-sensitive tissue lining the inner surface of
the eye; converts images focused by the eye’s optical system into electrical impulses and transmits them to the brain via the optic nerve
Macula – Small area of the retina that gives us our
detailed central vision
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Iris – Colored part of the eye that controls the size of
the pupil Pupil
– Round opening in the center of the iris; becomes smaller in bright light and larger in dim light
Cornea and lens focus the light (image) on the retina
Power of the eye (cornea or lens) becomes stronger or weaker
Axial length of the eye becomes longer or shorter
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Light (image) focused in front of the retina Power of the eye (cornea or lens) becomes stronger
– Cornea: increased central thickness or steeper curvature – Lens: increased thickness, steeper curvature, moved forward, or
higher refractive index (degree to which transparent material can bend light)
Eye becomes longer; retina moved back
47 year old Caucasian male Office visit Last full eye exam 9 months prior Complaint
– “Vision is blurry far away with my glasses for 2 weeks” (sudden change in vision)
20/50 vision in both eyes with his glasses
20/20 vision with a stronger near-sighted prescription
Eye health was normal What should I do?
Very thirsty for the last month Tentative diagnosis: diabetes Sent him to get his glucose levels (blood
sugar) tested
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Type 2 diabetes confirmed Patient was started on diabetes medication
and his vision returned to normal in 3 weeks
Life-long disease in which there are high levels of glucose in the blood (blood sugar)
Type 1 diabetes – Body does not produce insulin (hormone
needed to move glucose into the cells, so it can be stored and used later for energy)
Type 2 diabetes – Most common type of diabetes – Body does not produce enough insulin or the
body resists the effects of insulin
Very thirsty and frequent urination – Also, very hungry, weight loss, fatigue, slow
wound healing, more vaginal or yeast infections
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Sudden rise in glucose level (blood sugar)
Glucose moves into the lens of the eye
Water follows the glucose and the lens swells (thicker with a steeper curvature)
Lens is now more powerful resulting in more near-sightedness
After glucose levels are under control with medication, vision will usually return to normal in about a month – Water moves out of the lens and the lens
returns to it’s original power
Clouding of the crystalline lens with age
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Most common type of cataract Hardening and yellowing of the center of the lens Can make the lens more powerful and cause a gradual
myopic (near-sighted) shift in vision by increasing the refractive index of the lens
Changing the patient’s spectacle prescription to a stronger near-sighted correction will often improve the distance vision
Sudden temporary myopic shift in vision from drugs
Case history is important Can occur within a day to weeks of starting the
drug Prevalence
– Uncommon, but most common are sulfa or sulfa-related drugs
– Can be a very large near-sighted shift in vision
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Certain antibiotics (Bactrim, Septra) – sulfa drug
Topamax – Sulfa-related drug – Used for epilepsy, migraines,
or weight loss
Mechanism of action for sulfa or sulfa-related drugs – Crystalline lens moves forward and increases
the power of the eye
Management – Reassure the patient that vision should clear up
within a few days to weeks after discontinuing the drug
– May not necessarily reoccur with re-administration of the drug
Contact lens overwear, injury, ocular herpes infection – Increased central corneal thickness and/or a
steeper corneal curvature will increase the power of the cornea
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Can cause a small temporary myopic shift Fluid retention can cause corneal swelling
and increase the power of the eye Reverts back to normal after delivery or
after stops breastfeeding Keep in mind gestational diabetes
Become more near-sighted in dim light Younger people more likely to be affected
(less than 40 years old)
Most likely cause is “dark focus” – In dim light, there is
not enough visual stimulus, so the eye adopts an intermediate focus
– Varies, but usually focused about 1 meter in front of you
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Night driving probably not affected by night myopia – Studies found that driving with headlights was
not dark enough to cause “dark focus”
Daytime photoreceptors (cones) give us our sharp, clear, fully colored vision
Photoreceptors used at night (rods) are more sensitive to light, but give us less detailed vision
Need to rule out eye diseases that affect night vision
Possibly developed a small amount of myopia or astigmatism or there is a small change in your glasses or contact lens prescription
Larger pupil at night to let in more light – Smaller pupil during the day increases the
depth of focus (range of clarity); can conceal a small amount of uncorrected myopia or astigmatism
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26 year old female works as an office administrator
Complaint – “After working on the
computer all day, my vision is blurry for a few minutes when I look far away”.
Focusing muscles are in a spasm and unable to relax to look far away
Associated with prolonged near work
Need to rule out more serious causes such as: disease, infection, inflammation, drugs
Treatment – Treat any underlying cause – Vision therapy to relax focus
Light (image) focused behind the retina Power of the eye (cornea or lens) becomes weaker
– Cornea: flatter curvature – Lens: decreased thickness
Axial length of the eye becomes shorter; retina moved forward
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Small central area of the retina with a high concentration of cone photoreceptors
Central, sharp, detailed, color vision
Fluid leaks under the macula and pushes the retina forward
Light (image) is focused behind the retina and causes a small hyperopic (far-sighted) shift in vision
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20-50 year old men; can also affect women Usually in one eye Symptoms
– Blurred or dim central vision – Distorted vision – Colors appear washed out – Or possibly no symptoms
Associated with higher levels of cortisol (hormone released during times of physical or psychological stress)
Who is at risk? – Type A personality, stressful event, pregnancy,
certain medications, Cushing’s Syndrome Typically heals without treatment in 3-4
months Usually regain good vision; can be recurrent
Aphakia – Crystalline lens in
the eye removed and no intraocular lens implanted
– Become very hyperopic
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Light rays do not focus at a single point on or near the retina Cornea is not perfectly spherical
(“basketball”) Cornea is more curved (steeper) in some
meridians than others; steepest meridian is usually perpendicular to the flattest meridian (“football”)
Regular astigmatism Irregular astigmatism
– Usually associated with eye diseases
Cornea: change in the shape (power) of the cornea
Lens: change in the lens power along a meridian or a change in the positioning of the lens in the eye
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Oil gland in the eyelid gets infected and inflamed
Red, tender lump in the eyelid
Can put pressure on the cornea and cause an irregular astigmatism by reshaping the cornea
Frequent warm compresses – Apply for 10 minutes, four times a day
Antibiotics may be necessary
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Mass of tissue that grows onto the cornea Usually occurs in the 3:00 or 9:00 position
Can flatten the cornea in that area and cause irregular astigmatism
Associated with ultraviolet radiation (sun exposure)
Protect eyes from UV rays from the sun (sunglasses)
Artificial tear eye drops for irritation Anti-inflammatory eye drops for redness Surgery is an option
– Possibility of re-growth
Middle of cornea thins and bulges forward forming a cone shape
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Abnormal curvature causes irregular astigmatism
Often begins during puberty
Rigid contact lenses or specialty contact lenses Corneal transplant if scarring or very poor vision
Intacs corneal ring implant – Flattens the central cornea
Corneal Collagen Cross-Linking (CXL) clinical trials
Riboflavin drops saturate the cornea which is then activated by UV light
Increases the amount of collagen cross-linking in the cornea; strengthens the cornea
Not a cure, but can slow the progression of keratoconus
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Injury – Ring of fibrous strands holding the lens in place can
break – Can cause irregular astigmatism (lens tilted or looking
through the peripheral portion of the lens)
Connective tissue disorder resulting in heart problems, skeletal disorders (long arms, legs, fingers), lung and central nervous system problems, and eye problems
Fibrous strands made of connective tissue that hold the lens in place may weaken and break; lens usually moves upward
Can cause irregular astigmatism (lens tilted or looking through the peripheral lens)
Need to move the focus of light (image) onto the retina to see clearly
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Flatten the cornea with a rigid contact lens worn during sleep; weaken the power of the cornea
Remove the contact lens in the morning
See clearly for about one day
Flatter/weaker cornea does not bend the light as much; the image moves back and focuses on the retina
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Corrects low to moderate amounts of myopia (near-sightedness) and low amounts of astigmatism
Reversible Half the cost of LASIK
Cut a flap in the cornea, reshape the cornea with a laser by removing tissue, then reposition the flap
Can correct myopia, hyperopia and astigmatism
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Steeper/stronger cornea bends the light more; the image moves forward and focuses on the retina
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Flattening the steeper meridian of the cornea to focus the image on the retina
Implant lens in front of the eye’s natural lens and behind the iris
FDA-approved for correction of myopia More invasive surgery; more expensive Alternative for patients not suitable for
LASIK or other refractive surgeries due to very high myopia
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Remove the crystalline lens in the eye and replace it with a new lens implant with a different power
Like cataract surgery without the cataract More invasive surgery; expensive Cannot change focus to look up close with a
standard monofocal lens implant