OPHTHALMOLOGY I
EVALS 06
TRANS 01
BLURRING 1: ERROR OF REFRACTION, CATARACT, AMBLYOPIA
Dr. Juanchito Bernardo Jr.
💡 Superior rectus,
TOPIC OUTLINE
● The eyeball is secured by 4 recti muscles (
Inferior rectus, Medial rectus, Lateral rectus)
I. Anatomy of the Eye
II. 5-Point Ophthalmologic Examination
III. Error of Refraction
A. Emmetropia
B. Myopia
C. Hyperopia
D. Presbyopia
E. Astigmatism
F. Management
1. Glasses and Contact Lenses
2. Refractive Laser Surgery
IV. Cataract
A. Case: 70 y/o Male
B. Types
C. Management
D. Complications
V. Amblyopia
A. Case: 25 y/o Male
B. Mechanism
C. Types
1. Refractive Amblyopia
2. Strabismic Amblyopia
3. Deprivation Amblyopia
D. Management
VI. Summary
📖 - From Book (cite sources)
📝 - From Old Transes
🚩 - Important
Figure 2. Cross-sectional diagram of the eye
LEGEND
IMPORTANT TERMINOLOGIES
📌
Disclaimers/Transer’s notes
- Undiscussed Sections
- Nice to Know
💡
📢
This transcription follows the flow of Dr. Bernardo’s lecture video. Use of
was
omitted since majority of the information were audio inputs. First 2 topics are additional
references posted on Moodle. Additional notes were lifted from the handout, older
transes, Google, and books. Outline for Error of Refraction does not include
sub-subheadings as they were the same for all - case and pathophysiology.
OBJECTIVES
●
●
●
●
●
Diagnose error of refraction given a clinical scenario
Differentiate the kinds of errors of refraction
Diagnose cataract given a clinical scenario
Propose the appropriate management plan of cataract
Recognize the presenting signs and symptoms of post cataract
endophthalmitis
● Diagnose amblyopia given a clinical scenario
● Recommend its appropriate management
I. ANATOMY OF THE EYE
● T/N: This section was transcribed from the Youtube reference
posted on Moodle
● Link
to
the
video:
https://www.youtube.com/watch?v=FNzh_5cTlMY
● CORNEA
→ A thick transparent layer that lies centrally in the surface of
the eye and covers both the pupil and the iris
▪ Needs to be transparent to allow ample light to enter the
eye and reach the retina at the back of the eye where
images of our sight is formed
▪ Transparency is due to regularity if the arrangement of
cells and its extracellular matrix
→ It is the major refractive surface for incoming light and
provides the main focusing power of the eye
→ Tear film in the surface of the cornea refracts light the most
→ Covered by a very thin epithelial layer which is similar to a
layer of skin
▪ Scratching results to CORNEAL ABRASIONS
− A very common eye injury
− Very painful because the cornea is densely innervated
by nerves from the ophthalmic branch of the trigeminal
nerve or V1
→ The cornea is avascular and contains very few immunologic
cells, making corneal transplant a highly successful
procedure
● LENS
→ Fine-tunes that focus
Allow the eye to focus on objects at varying distances
▪
→ Directly behind the iris
● SCLERA
→ White structure that entirely surrounds the cornea
→ A fibrous connective tissue that encases the intraocular
contents
→ Most external layer
● CONJUNCTIVA
→ A thin translucent epithelial layer covering the sclera
→ BULBAR CONJUNCTIVA
▪ Covers the sclera that then continues and reflects off the
eye, onto the eyelid, and becomes the PALPEBRAL
CONJUNCTIVA
💡
Figure 1. Dissection of the eye outlining the cornea
Group 7A
Page 1 of 13
OPHTHALMOLOGY I Blurring 1: Error of Refraction, Cataract, Amblyopia
Table 1. Recap of the structures
Structures
Remarks
ANTERIOR
Cornea
At the very front of the eye
Anterior chamber space between the cornea and the iris
Iris
Lies at the back edge of the anterior chamber
Lens
Figure 3. Cross-section showing the eyelids. Conjunctiva and sclera start at
the edge of the cornea (green mark) and the conjunctiva extends over the
sclera, reflects off of the sclera and onto the surface of the eyelid. This
creates an epithelial barrier between the external environment and the
inside of the orbit.
● Puncturing of the cornea results in the outflow of aqueous
humor out of the ANTERIOR CHAMBER, which is the space
between the cornea and the iris.
Directly behind the iris and pupil
Zonules
Hold lens in place
Fibrous strands that emanate from the ciliary body
Ciliary body
Forms a ring behind the iris
Muscle that contracts and relaxes to change the
shape of the lens
Vitreous jelly
Partially liquid component of the eye that helps to
keep the eye’s shape
Optic
Circular portion of the lens
Haptic
Arms of the optic
Retina
Pale translucent layer at the back of the eye
Composed of two main layers
Inner layer: neurosensory retina made up of
photoreceptors and other cells which convert light
into neural impulses that travel to the brain,
specifically the virtual cortex in the occipital lobes
Outer layer: retinal pigmented epithelium which
forms the blood retinal barrier and whose dark
pigment absorbs light as it enters the eye
Receives light that the lens has focused and
converts it into neural signals, then sent to the
brain for visual recognition.
Optic Nerve
Found on the most posterior aspect of the eye
Also known as CN II, transmits sensory
information in the form of impulses from the retina
to the brain
Uvea
Made up of choroid, ciliary body, and iris
Choroid - vascularized layer external to the retina
POSTERIOR
Figure 4. Puncturing of the cornea and the outflow of aqueous humor
● LIMBUS
→ Darker circle where the sclera meets the cornea
● IRIS
→ Seen beneath the cornea
→ A colored ring of muscle that separates the anterior chamber
from the crystalline lens
→ The undersurface of the iris is dark and everyone’s iris’, no
matter what color it is, has a dark undersurface, due to a
pigmented epithelium
→ Directly behind and attached to the iris is the ciliary body
● PUPIL
→ At the center of the iris
→ Appears dark because it is a negative space opening into the
interior of the eye
→ Primary action is to either constrict or dilate, effectively
regulating the amount of light entering the eye
Figure 6.
💡
💡 Optic zone and Haptics (from Google)
Figure 5. More complete cross-sectional anatomy of the eye
Group 7A
Page 2 of 13
OPHTHALMOLOGY I Blurring 1: Error of Refraction, Cataract, Amblyopia
● Power of the lens depends on its curvature and the difference in
refractive indices.
● Eye
→ Can be thought of as a series of lenses whose main goal is to
focus light rays from the external world unto the retina
▪ cornea, aqueous, lens, vitreous
→ Total converging power: 60 diopters
▪ Main refractive components:
− Cornea: ~ +40 Diopters
− Lens: ~ +20 Diopters
II. 5-POINT OPHTHALMOLOGIC EXAMINATION
● T/N: This additional reference that is posted on Moodle was
transcribed last year during our Physical Diagnosis lecture on
Ophthalmology.
● Link to the video:
https://www.youtube.com/watch?v=DXMMrH9lW3k
● Link to the trans (Part IV):
https://drive.google.com/file/d/1_vhcnEQ-qWyhlDbmwVUOk2l8
8beTfFjp/view?usp=sharing
→ Transes Name: 24.3 PD Ophthalmology Physical
Examination from Batch 2023 YL2 Files (will be uploaded in
this module’s folder for better access)
Figure 7. Anatomy of the eye
III. ERROR OF REFRACTION
Figure 8. Ciliary body and striations of the radially oriented ciliary
muscles. The ciliary processes attach to the lens and the zonules and
can change the shape of the lens to help focus light on the retina.
● Inside to outside:
→ Retina > retinal pigmented epithelium > choroid > sclera
→ All give shape to the eye, provide blood supply and nutrients,
and work to generate images of what is seen around.
📌
Undiscussed Section
● One of the most common causes of visual impairment
worldwide
● Present when the eye is unable to properly focus light rays on
the retina, resulting in a blurred vision
● How do we see clearly?
→ Light from an image is first bent or retracted by the cornea
and then again refracted by the lens to form a single point on
the retina
Lifted from Handouts
● Lenses can be viewed as a certain arrangement of prisms (light is
deflected towards the base of the prism)
● Converging lens (positive lens) can be thought of as 2 prisms
joined at the base.
● Diverging lens (negative lens) can be thought of as 2 prisms joined
at the apex.
Figure 10. How we see clearly (Emmetropia/Normal vision)
A. EMMETROPIA
● When light rays from an image are properly focused on a single
point on the retina without the eye exerting any effort
● Having normal vision
📌
Figure 9. Converging and diverging lenses
● Diopter
→ Unit of measurement of lens power
→ Measure of convergence or divergence
→ Reciprocal of focal distance
Group 7A
Undiscussed Section
Lifted from Handouts
Emmetropia
● Condition wherein parallel light rays fall into a pinpoint focus on the
retina
Ametropia
● Condition wherein parallel light rays DO NOT fall into a pinpoint
focus on the retina
● Myopia, hyperopia, astigmatism
● Correction:
→ Spectacles
Page 3 of 13
OPHTHALMOLOGY I Blurring 1: Error of Refraction, Cataract, Amblyopia
→ Contact lenses
▪ Soft, rigid gas permeable, hard, etc.
▪ Multifocal
→ Refractive Surgery
▪ PRK (photorefractive keratectomy)
▪ RK (refractive keratotomy)
▪ LASIK (laser-assisted in situ keratomileusis)
B. MYOPIA
1. CASE 1: 6 Y/O BOY
Figure 13. Axial myopia
● Needs to go in front of class to see presentations clearly
● Needs to sit close to TV
● Has no problem with viewing near objects, but find it difficult to
see distant objects clearly
● Ophthalmologic Examination
→ Visual acuity: 20/50 (both eyes)
▪ Improved to 20/20 on pinhole testing
→ The rest are unremarkable.
● Impression: ERROR OF REFRACTION
● Very easy to detect by using the PINHOLE
→ Improvement of vision with pinhole: indicative of error of
refraction
→ Works by blocking misaligned light rays and by only allowing
the central light ray to focus on the retina
Figure 14. Normally sized eye vs. elongated eye
● REFRACTIVE MYOPIA
→ In some instances, axial length is normal
▪ However, one of the refractory components of the eye is
bending light more than the normal
→ A cornea that is steeper than the normal will have a
consequent increase in its refractive power, resulting in the
bending of light in front of the retina
Figure 11. How pinhole works
● For those wearing glasses, try making a pinhole using a piece
of paper
→ Punch 2mm-hole in it and try it
● Type of error of refraction of the child: MYOPIA
→ Patient needs to move closer to distant targets
▪ because light is refracted in front of the retina
2. PATHOPHYSIOLOGY
Figure 15. Refractive myopia
● Rarely, an increase in the anterior-posterior diameter of the
lens will also result in myopia
📌
Figure 12. Myopia
● AXIAL MYOPIA
→ Most common type of myopia
→ Light is refracting in front of the retina because of an
increase in the axial length of the eye
→ Length of the eye: > 24mm
Group 7A
Undiscussed Section
Lifted from Handouts
Myopia
● Also known as NEARSIGHTEDNESS
● Condition wherein parallel light rays focus at a point in front of the
retina
● Can be axial (eyeball longer than average) or refractive (corneal
curvature steeper than average)
● Correcting myopia:
→ Use of divergent lens (negative or biconcave lens to neutralize
the convergent effect of the myopic eye) to focus light rays on the
retina
Page 4 of 13
OPHTHALMOLOGY I Blurring 1: Error of Refraction, Cataract, Amblyopia
C. HYPEROPIA
1. CASE 2: 33 Y/O MALE
●
●
●
●
●
Has difficulty seeing near targets clearly
Started to experience one year PTC
Finds himself squinting to make his vision clearer
Was always seeing well during childhood
Ophthalmologic Exam
→ Distal vision: 20/25 (both)
▪ Improved to 20/20 on pinhole testing
● Impression: HYPEROPIA
● In hyperopia, light is bent behind the retina
→ patients should be complaining of poor near vision
● Hyperopes
see
distant
objects
clearly
due
to
ACCOMMODATION
→ Process by which the lens increases its anterior and
posterior diameter by becoming more spherical
→ Used when we suddenly shift focus from a distant target to a
near target
2. PATHOPHYSIOLOGY
Figure 19. Accommodation in Hyperopia
Figure 16. Hyperopia
● Light rays are refracted behind the retina
● AXIAL HYPEROPIA
→ Short eyeball which makes the refracted light fall behind the
retina
Figure 17. Axial hyperopia
● REFRACTIVE HYPEROPIA
→ Less common
→ Flat cornea or an underpowered crystalline lens
● Hyperopes employ accommodation even while looking at
distant objects
→ In this way, they are able to bring the refracted light behind
the retina onto the retina; they seldom complain of blurring even
while looking at distant targets
● Most hyperopes, especially young hyperopes, have good
distant and near vision because of accommodation.
📌
Lifted from Handouts
Undiscussed Section
Hyperopia
● Also known as FARSIGHTEDNESS
● Condition wherein parallel light rays focus at a point behind the
retina
● Can be axial (eyeball shorter than average) or refractive (corneal
curvature flatter than average)
● Correcting hyperopia:
→ Use of convergent lens (positive or biconvex lens) to focus
light rays on the retina
Accomodation
● Principle: To focus on a nearby object, the brain sends out signals to
contract the smooth muscles of the ciliary body; this enables the
zonules to loosen up, which in turn increases the lens curvature
(lens thickens), and thereby increasing its converging power.
D. PRESBYOPIA
1. CASE 3: 45 Y/O MALE
● Has difficulty reading small prints
● First noticed this when he turned 40
● Says that the only way to make near targets clearer is to push
things farther away from him
● Ophthalmologic exam
→ Distant vision: 20/20
→ Near vision: Jaeger 7
▪ Tested since the patient is more than 40
● Is this hyperopia?
→ Key: patient’s age (45 years old)
2. PATHOPHYSIOLOGY
Figure 18. Refractive hyperopia
Group 7A
● At around the age of 40, ability to accommodate is lost. This is
called PRESBYOPIA
● Physiologic; normal part of aging
Page 5 of 13
OPHTHALMOLOGY I Blurring 1: Error of Refraction, Cataract, Amblyopia
Figure 22. Normal shape of cornea
● Some of us may be born with corneas that are irregularly
shaped like a football
→ Because of this inequality, the horizontal meridian will have a
different refracting power than the vertical meridian
Figure 20. Presbyopia
● Instead of being able to quickly shift focus from a distant target
to a near target, presbyopes will have a hard time seeing near
objects clearly
Figure 23. Comparison of normal cornea (left) and irregularly shaped
cornea (right).
📌
Figure 21. Vision of presbyopia. Note that the trees and the house from
afar are clear while the newspaper print is blurred.
Lifted from Handouts
Undiscussed Section
Presbyopia
● With aging (around 40 y/o), there is loss of focusing or
accommodative power of the human eye
● One would need plus lenses (presbyopic glasses/reading aids) to
make up for the lost automatic focusing power of the lens.
Figure 24. Unequal diameters of horizontal and vertical meridian
● The different meridians will then form two separate points where
light is refracted. This is called ASTIGMATISM
E. ASTIGMATISM
1. CASE 4: 10 Y/O FEMALE
● Poor distant vision
● Seeing shadows while looking at distant targets
● Distant vision: 20/30 (both eyes)
→ Improves to 20/20 on pinhole testing
● Improvement on vision on pinhole testing → error of refraction
2. PATHOPHYSIOLOGY
● Normal: The cornea should have a spherical shape.
→ The horizontal meridian should have the same diameter as
the vertical meridian
Figure 25. Astigmatism
● Reason why patients with astigmatism usually complain of
seeing shadows
●
Astigmatism may coexist with either myopia or hyperopia.
🚩
Group 7A
Page 6 of 13
OPHTHALMOLOGY I Blurring 1: Error of Refraction, Cataract, Amblyopia
Table 2. Summary of corrective lenses
Error of Refraction
Corrective lenses
Myopia
Minus (-)
Hyperopia
Plus (+)
Astigmatism
Toric
Figure 26. Example of how patients with astigmatism see
📌
Lifted from Handouts
Undiscussed Section
Astigmatism
● Condition wherein the curvature of the cornea or of the lens is not
the same in different meridians
● Parallel light rays focus on 2 separate lines or planes
● Curvature of the eye resembles one side of a football, instead of a
basketball (in eyes without astigmatism)
● Correcting astigmatism:
→ Use of cylindrical lens (lenses each with power in two different
meridians/axes)
● Types:
→ Simple myopic - one image on the retina, one image in front of
the retina
→ Simple hyperopic - one image on the retina, one image behind
the retina
→ Compound myopic - both images in front of the retina
→ Compound hyperopic - both images at the back of the retina
→ Mixed astigmatism - one image in front of the retina, one image
at the back of the retina
💡
Nice to Know | Lifted from 2021 Trans
Figure 27. How corrective lenses work
2. REFRACTIVE LASER SURGERY
● Some patients may not be amenable to conventional
management and might pursue a surgical type of refractive
correction
● The most popular form of refractive surgery is through laser
reshaping of the cornea
→ Can be done for myopia, hyperopia, and astigmatism
Regular Astigmatism
● Two principal meridians are perpendicular to one another but
with varying steepness and power.
● Other classifications of regular astigmatism:
→ Astigmatism with the rule - greater refractive power along
the vertical meridian; typically in younger patients
→ Astigmatism against the rule - greater refractive power
along the horizontal meridian; typically in older patient
→ Oblique astigmatism - principal meridians do not lie within
20 degrees of the horizontal and vertical meridians.
F. MANAGEMENT
1. GLASSES AND CONTACT LENSES
● The most common management and safest way of correcting
errors of refraction is through glasses
● Some people may opt to use contact lenses which are also
readily accessible
● Since myopes are generally over-refracting, MINUS LENSES
are prescribed
● Since hyperopes are underpowered, PLUS LENSES are given.
● TORIC LENSES for astigmatism
Group 7A
Figure 28. Lasik surgery. For example in myopia, the cornea is flattened to
have a decrease in the refractive power of the eye.
Page 7 of 13
OPHTHALMOLOGY I Blurring 1: Error of Refraction, Cataract, Amblyopia
💡
Nice to Know | Lifted from video lecture
Review Question
At what distance will a 50-year-old hyperope have difficulty with
viewing clearly?
a. Both far and near
b. Far
c. Near
Answer: a. Both far and near
The patient will have difficulty in both far and near vision, because
at 50, we expect the patient to become presbyopic. The patient
would have lost most of his/her ability to accommodate.
💡
● Physical Examination
→ VA testing
▪ Vision on the left: 20/200
− Did not improve on pinhole testing
→ Gross examination
▪ An opacity was noted
▪ Which part of the eye was opacified?
− The cornea is clear if the iris details can be seen very
well.
− Hence, then it can be safely assumed that it is the lens
that has opacified
Nice to Know | Surgery Platinum, Chapter 30: Ophthalmology
Error of Refraction
● Symptoms: blurring of vision, decreased vision at near
● Signs: vision improves to 20/20 with pinhole; 20/20 far vision
but unable to read J1 using near chart
● Treatment: spectacle correction
● Total refractive power of the eye is 60 diopter (cornea: 40D,
lens: 20D)
Figure 30. The cornea (red arrow) is the transparent structure in front of the
colored part of the eye called the iris (blue arrow)
Table 3. Types of errors of refraction
Type
Remarks
Myopia
Image focuses in front of the retina, seen in
steep corneas or long eyeballs, corrected with
concave or minus lenses
Hyperopia
Image focuses behind the retina, seen in flat
corneas or short eyeballs, corrected with convex
or plus lenses
Astigmatism
Image on two meridians focuses on different
points, there is a difference in the corneal
curvature between the two meridians, corrected
by cylindrical lenses
Presbyopia
Loss of lens elasticity or accommodation
resulting in inability to focus for near vision,
corrected by reading adds (plus lenses)
IV. CATARACT
● Defined as any opacity in our natural crystalline lens
● Most common cause of reversible blindness worldwide
A. CASE : 70 Y/O MALE
Figure 30. The lens is the transparent structure that sits behind the iris
→ Pupillary constriction was noted upon light stimulus
→ Fundoscopy: absence of red orange reflex on left eye
Figure 29. Progressive blurring on the left eye (left); Opacification
(right)
● History
→ Patient consults for progressive blurring on the left eye
which started a year ago
→ He also noticed during the past year he was required several
trips to the optical shop because he was frequently
changing his glasses prescriptions
→ During daytime, he experiences light sensitivity to the point
that it was unbearable
→ During the past year, he also found nighttime driving difficult
because of glare
Group 7A
Figure 31. Absence of red orange reflex on left eye
● Impression: CATARACT
→ 70 male
→ Progressive blurring
→ Light sensitivity, nighttime glare, frequent prescription
glasses change
→ Lens opacity; Normal pupillary response
→ Poor or absent red orange reflex on affected eye
Page 8 of 13
OPHTHALMOLOGY I Blurring 1: Error of Refraction, Cataract, Amblyopia
B. TYPES
D. COMPLICATIONS
● Age-related
→ Most of the cataracts encountered clinically
→ If most of us live long enough, most of us will develop
cataract
● Congenital
→ During birth or early childhood
● Secondary (Acquired)
→ To systemic diseases
One of the most common is diabetes
→
▪ Hyperglycemia induces lens swelling and formation of
sorbitol which then induces opacification of the lens.
→ This type of cataract usually presents earlier than
age-related cataracts.
● Steroid-induced cataract
→ Some medications may induce early cataract formation such
as chronic use of systemic or topical steroids.
● INFECTIOUS ENDOPHTHALMITIS
→ The most dreaded complication of cataract surgery
→ If this is not addressed early, it may result in the rapid loss
of vision.
→ Presenting signs and symptoms:
▪ Severe pain
▪ Periocular swelling
▪ Rapid decline in vision
▪ Upon ophthalmologic exam: hazy cornea, a very
inflamed eye, and also pus in the anterior chamber
→ Risk factors of endophthalmitis:
▪ Pre-operative:
− Diabetes mellitus
− Immunocompromised state
− Pre-existing lid or nasolacrimal infection
− Presence of any ocular or periocular infection prior to
surgery necessitates postponement.
▪ Intra-operative:
− Prolonged surgery
− Vitreous loss
▪ Post-operative:
− Wound leak or dehiscence
→ Management
▪ Get samples for culture and sensitivity with
simultaneous injection of intravitreal antibiotics
▪ Severe cases may require surgical debridement of the
infectious load.
🚩
Figure 32. Diabetic cataract (left); Steroid induced cataract (right)
● Post-traumatic
→ can also cause lens opacification
Figure 33. Direct penetrating corneal injury from a concrete nail also hit the
lens; black lines seen are sutures that were needed to close the cornea
C. MANAGEMENT
● Surgical removal called PHACOEMULSIFICATION with
intraocular lens implantation
● Process involves two steps:
→ Removal of cataractous lens using an aspirating ultrasonic
machine
▪ Red orange reflex can then be appreciated.
→ Implantation of an artificial intraocular lens
▪ Natural lens is responsible for the ⅓ total refractive power
of the eye and if cataract is removed and lens is not
implanted, the eye will become underpowered and will not
be able to refract light properly onto the retina
● To improve vision to improve patient’s quality of life
● Some cataracts may not be removed.
→ i.e. medically unstable patients or upon doing surgery, you
endanger the patient’s life
● > 99% of cataract surgeries worldwide are successful.
● <1% suffer complications.
Group 7A
💡
Nice to Know | Surgery Platinum, Chapter 30: Ophthalmology, Page 510
Endophthalmitis
● Symptoms:
→ Pain
→ Decreased vision
→ History of trauma
→ Surgery
→ Dental caries
→ Systemic infection
● Signs:
→ Conjunctival infection
→ Hypopyon
→ Fibrin in anterior chamber
→ Vitreous cells
→ Haze
● Causes:
→ Post traumatic
→ Postoperative
→ Endogenous
● Treatment
→ Hospitalization
→ Ocular UTZ if no view of posterior pole
→ Topical and systemic antibiotics
→ Do not start steroids
→ Diagnostic vitreous tap with intravitreal antibiotics
→ May do pars plana vitrectomy with intravitreal antibiotics for
VA of light perception
Page 9 of 13
OPHTHALMOLOGY I Blurring 1: Error of Refraction, Cataract, Amblyopia
V. AMBLYOPIA
● When vision does not properly develop during childhood
● A condition in which the visual input from the eye is not
processed by the brain
● Sometimes referred to as LAZY EYE
There is decreased vision due to abnormal visual
●
development during infancy or childhood. (Batch 2022 Trans)
Critical time is up to 7 years old: should be corrected before
●
the child reaches the age of 8. (Batch 2022 Trans)
📝
📝
📝
Lifted from 2022 Trans
●
There is decreased vision due to abnormal visual development
during infancy or childhood.
Critical time is up to 7 years old: should be corrected before
the child reaches the age of 8.
●
C. TYPES OF AMBLYOPIA
1. REFRACTIVE AMBLYOPIA
● Uncorrected refractive error since childhood.
● Refractive error only on one eye
● For example: 6-y/o child who sees 20/20 on one eye but sees
20/100 on the other because of refractive errors.
→ 6 year old child
→ OD: 20/100 (myopic)
→ OS: 20/20
●
If left untreated during childhood, the eye with poor vision
will not fully develop its visual function even if you put glasses
later in adulthood.
🚩
📝
Lifted from 2022 Trans
●
A. CASE: 25 Y/O MALE
● Blurring on the right eye
● Recalls that when he was 6 years old, he noticed his right eye
was not seeing very well. He was taken for consultation,
wherein an eye doctor recommended glasses. However, due to
“certain beliefs” his parents did not give consent to glasses
prescription.
● Ophthalmologic Exam:
→ OD: 20/60
▪ Not improved with pinhole testing
→ OS: 20/20
→ The rest are unremarkable.
▪ Grossly normal looking OU
▪ Soft on palpation tonometry
▪ Full EOMs
▪ (+) ROR, DDB, 0.3 C/D ration, no hemorrhages/exudates
● Impression: AMBLYOPIA (may be refractive)
Amblyopia – functional reduction in visual acuity because
→
of abnormal visual development early in life. (Batch 2022
Trans)
●
The brain will preferentially accept signals from the good
seeing eye therefore the bad seeing eye will not develop
properly.
Wearing eyeglasses early will help correct the error of
refraction and prevent amblyopia as well.
2. STRABISMIC AMBLYOPIA
● Ocular misalignment
● Only the aligned eye is perceiving and processing images
●
If left uncorrected, the other eye which is deviated will soon
develop amblyopia.
🚩
📝
B. MECHANISM
● Before the age of 7, our eyes form connections to the brain. By
doing so, this makes what we see gets processed by the visual
cortex.
💡
Figure 36. Strabismic amblyopia (ocular misalignment)
Nice to Know | Lifted from 2021 Trans
Strabismic Amblyopia
● The brain recognizes signals from the good eye only and
suppresses those from the bad eye to prevent doubling of
vision.
● Visual acuity is maintained on the good eye for fixation.
● Misalignment of the brain may suppress the image from the
strabismic eye.
● Done so that patients with childhood strabismus do not see
double, however if left untreated, the suppressed eye will be
amblyopic.
Figure 34. Mechanism of normal vision development
● If one eye is not seeing very well, the brain would prefer visual
inputs coming from the better eye and will ignore vision coming
from the poorly seeing eye. Because of this, the poorly seeing
eye will not develop proper connections to the brain. This is
called AMBLYOPIA.
Figure 37. Large Angle Infantile-Onset Esotropia. The right affected eye is
placed medially. The signals this eye transmits to the brain is suppressed in
order to prevent double vision.
Figure 35. Mechanism of amblyopia
Group 7A
Page 10 of 13
OPHTHALMOLOGY I Blurring 1: Error of Refraction, Cataract, Amblyopia
3. DEPRIVATION AMBLYOPIA
● There is a media opacity on the right eye because of the
congenital cataract.
● Because of the cataract on the right, no images are being
perceived and thus, no connections from the right eye to the
brain are being formed.
💡
Nice to Know | Lifted from video lecture and 2022 Trans
Review question
The mother of a 2 y/o patient diagnosed with congenital cataract
decides that they will have the patient undergo surgery when the
patient is 18 y/o. Do you agree?
a. Yes
b. No
c. I don’t know
Answer: NO. Recall that congenital cataract must be corrected
until 7 years old to prevent developing amblyopia.
VI. SUMMARY
📝
Figure 38. Congenital Cataract
Lifted from 2022 Trans
Deprivation Amblyopia
● Seen in congenital cataract due to lack of sensory input
secondary to very dense cataract.
● If not corrected early, the patient may develop deprivation
amblyopia.
● However, if it is removed during adulthood, 20/20 vision is not
assured since the patient was used to seeing blurred vision.
D. MANAGEMENT
Figure 39. Patching
🚩
● Treat the underlying cause.
●
Patch the better eye
→ It is done in order to force the lazy eye to start working and
hopefully, to start developing proper connections to the brain.
→ The earlier this is done, the better
▪ preferably, within the first few years of life
− as the child grows older, the treatment success rate
drops significantly
●
The golden period for amblyopia treatment is during the 1st
7 years of life (preferably)
📝
● Myopia or hyperopia may be axial or refractive
→ Axial - globe anterior posterior diameter
▪ Axial length > 24 mm or <22 mm
− Normal: 22-24 mm
→ Refractive - corneal steepness (power)
● Astigmatism is due to unequal corneal meridians (each
meridian has different powers)
● Presbyopia is the physiologic loss of accommodation because
of aging.
● Cataracts are defined as any lens opacity.
→ Most common cause of reversible blindness worldwide
→ Majority are age-related.
→ Presents with a progressive type of blurring and should NOT
be readily considered in patients complaining of sudden
blurring
→ Management: phacoemulsification with intraocular lens
implantation
→ Most
devastating
complication
is
infectious
endophthalmitis.
● Amblyopia, sometimes referred to as “lazy eye”, is a condition
wherein vision does not properly develop during childhood.
Visual input from the eye is not processed by the brain.
→ Three Types:
▪ Refractive Amblyopia: uncorrected refractive error since
childhood, occurring only on one eye
▪ Strabismic Amblyopia: ocular misalignment
▪ Deprivation Amblyopia: seen in congenital cataract due
to lack of sensory input secondary to very dense cataract.
→ Management
▪ Treat the underlying cause
▪ Patch the better eye which is preferably done within the
first few years of life
REVIEW QUESTIONS
SIMPLE TASKS (2022)
Figure 40. Mechanism of patching the better eye
Group 7A
1. What type of error of refraction is present when the
refracted light from an image falls in front of the retina?
a. Presbyopia
b. Hyperopia
c. Myopia
2. What type of error of refraction is present when the
refracted light from an image falls behind the retina?
a. Presbyopia
b. Hyperopia
c. Myopia
Page 11 of 13
OPHTHALMOLOGY I Blurring 1: Error of Refraction, Cataract, Amblyopia
3. What type of error of refraction is present when the
refracted light from an image forms two separate points on
the retina?
a. Astigmatism
b. Hyperopia
c. Myopia
4. Which symptom is NOT indicative of a cataract as the
cause of blurring?
a. Painless
b. Gradual or progressive blurring
c. Sudden loss of vision
5. What is the only management of a cataract?
a. Oral Medications
b. Surgery
c. Eyedrops
6. When is the best time to operate on a congenital cataract?
a. At 18 years of age
b. As soon as possible
c. After 7 years old
Answers: c, b, a, c, b, b
SIMPLE TASKS (2022)
1. A 25 year old call center agent consults because of
difficulty reading small prints with associated headaches.
Visual acuity is 20/25 for both, which improved to 20/20 on
pinhole. What is the most probable type of error of
refraction does the patient have?
a. Presbyopia
b. Hyperopia
c. Myopia
d. Amblyopia
2. Which part of the uvea is visible on gross examination?
a. Choroid
b. Retina
c. Iris
d. Ciliary body
3. What makes young hyperopes have good distant vision?
a. Fusion
b. Suppression
c. Convergence
d. Accommodation
4. An 8 year old boy was brought for consultation because of
difficulty seeing distant targets. He describes that he sees
distant letters as having shadows. Distant visual acuity is
at 20/40 which improved to 20/20 on pinhole testing. What
is the most probable cause of his blurring?
a. Presbyopia
b. Hyperopia
c. Myopia
d. Astigmatism
5. A 12 year old girl was brought for consultation because of
poor vision on the right which was noted on routine
school physical examination. Visual Acuity on the right is
20/50, which did not improve on pinhole testing; left is
20/20. The rest of the ophthalmologic exam are
unremarkable. What is your impression?
a. Glaucoma
b. Uveitis
c. Childhood cataract
d. Amblyopia
Group 7A
6. A 69 year old female came in with blurring of vision. You
note the following findings. Which of the following is
TRUE of this condition?
a. Myopia is risk factor
b. Treatment is surgical intervention
c. Visual loss is sudden
d. Hemorrhages are due to retinal neovascularization
7. Which of the following is part of the uvea?
a. Optic nerve
b. Retina
c. Ciliary body
d. Cornea
8. A 50 year old female consults because of difficulty reading
small prints, which she recalls started 10 years ago. On
examination, her distant visual acuity is 20/20 for both;
while near vision is at Jaeger 10. What is your
impression?
a. Presbyopia
b. Hyperopia
c. Amblyopia
d. Astigmatism
9. What simple clinical test will point to an error of refraction
as the cause of blurring?
a. Pinhole testing
b. Tonometry
c. Pupillary testing
d. Fundoscopy
10. A 25 year old patient suffered eye trauma which resulted
in flattening of his right cornea. What is your expected
error of refraction?
a. Presbyopia
b. Hyperopia
c. Myopia
d. Amblyopia
11. A patient did not receive an intraocular lens implant
during cataract surgery, if the axial length of the eye is
23mm, what type of error of refraction will result post
operatively?
a. Amblyopia
b. Hyperopia
c. Myopia
d. Astigmatism
Page 12 of 13
OPHTHALMOLOGY I Blurring 1: Error of Refraction, Cataract, Amblyopia
12. A patient seeks consult at the emergency room because of
severe right eye pain and blurring. Upon history, you learn
that 3 days ago, he had cataract surgery on the affected
eye. What is the most probable impression?
a. Retinal detachment
b. Angle closure
c. Infectious endophthalmitis
d. Vitreous hemorrhage
13. A 6 year old boy was brought for consultation because of
difficulty viewing distant targets. Upon visual acuity
testing, both eyes tested 20/50 which improved to 20/20 on
pinhole. What is your impression?
a. Hyperopia
b. Myopia
c. Amblyopia
d. Presbyopia
Answers: b, c, d, d, d | c, c, a, a, b | b, c, b
REFERENCES
● Bernardo, J. (2021) Blurring 1 [Videos].
Group 7A
Page 13 of 13