NBEO Part 1 || 100% Correct.
A 32-year old female is seen at your office complaining of a recent onset of blurred vision, only
at a distance. A thorough case history reveals that she recently began taking a new medication
which you correctly assume has induced myopia. Which of the following medications is MOST
likely to be the culprit? correct answers Isotretinoin, birth control pills, and diuretics, among
many other drugs, can cause myopia in some patients. Myopia mostly likely results from corneal
swelling, which steepens the curvature of the cornea. Drugs that cause swelling of the lens,
accommodative spasm, or edema of the ciliary body will also result in myopia. A reduction in
the dose of the medication or cessation of the offending drug will usually result in reversal of
nearsightedness. Fish oil, Tylenol, and Tums have not been shown to have a correlation with
transient myopia development.
An increased rate of molecular movement down its respective concentration gradient via help
from carrier proteins refers to which type of transportation? correct answers Facilitated diffusion
is described as the net movement of molecules down its concentration gradient whose rate of
diffusion is increased via the use of carrier proteins. Passive diffusion refers to the movement of
molecules through a plasma membrane from an area of high concentration to an area of low
concentration without the use of carrier molecules. Active transport implies the movement of
material against its respective concentration gradient. This type of transport requires energy and
enlists the use of specific carrier proteins. Lastly, group translocation is defined as the chemical
modification of a molecule while it is being transported into a cell; for example, sugars are often
phosphorylated during transportation.
A 24-year old female patient presents at your office complaining of side effects that began when
she started using Patanol to treat her ocular allergies. She reports complete compliance with her
eye drop administration. Which of the following symptoms is MOST likely associated with
olopatadine (Patanol) use? correct answers Topical antihistamines and mast cell stabilizers such
as Patanol (olopatadine) are commonly prescribed to relieve the symptoms associated with
ocular allergies. They are a very effective class of medication due to their dual action
mechanisms. Topical antihistamines that possess this dual action are olopatadine (Patanol),
ketotifen fumarate (Zaditor), azelastine (Optivar), and epinastine (Elestat). The aforementioned
drops serve to alleviate itching and redness by blocking H1 receptors as well as inhibiting mast
cell and basophil degranulation. Side effects of topical antihistamine/mast cell stabilizers include
stinging upon instillation, headaches, and adverse taste (don't forget to inform your patients
about punctual occlusion!). Tachycardia, depression, gastrointestinal discomfort, and visual
hallucinations have not been reported with Patanol use.
A 63-year old female is seen at your office with a chief concern of blurry vision in the morning
that takes about an hour to resolve before she can see clearly again. Biomicroscopy reveals
endothelial guttata. You correctly diagnose her with moderate Fuch's dystrophy. Which
ophthalmic drop would be of MOST benefit to her? correct answers Sodium chloride is a topical
hyperosmotic agent used to relieve stromal edema caused by endothelial decompensation.
Topical steroids work well to decrease swelling caused by inflammation. In the above case, the
corneal edema is not mitigated by an inflammatory response. Tobramycin and Vigamox would
,be of no benefit since there is no active infection, and prescribing either of these would only lead
to corneal toxicity or increased pathogen resistance over time.
A deficiency of which vitamin leads to prolonged dark adaptation? correct answers A deficiency
of vitamin A causes prolonged dark adaptation. Vitamin A is classified as a retinoid, and its
active form is retinol. Retinol is necessary for the formation of rhodopsin, a pigment used by
rods. Rods are most active in situations with dim illumination. Less rhodopsin results in fewer
rods being able to respond in low levels of light, causing prolonged dark adaption.
+1.50-1.50 x 090 is required to neutralize a reflex in retinoscopy with a working distance of 50
cm. What is the resulting NET retinoscopy finding? correct answers A working distance of 50
cm creates a divergent wave of 2.00 D that is neutralized by retinoscopy in addition to the
patient's refractive error. Therefore, + 2.00 D must be subtracted from the spherical portion of
the findings. To determine how much to subtract from the gross findings, one must first calculate
the reciprocal of the working distance in meters. In our case, 1/0.5 = 2. Therefore +1.50 (the
spherical gross findings) -2 = -0.50-1.50 x 090. Remember NET is the final result, this is found
after the working distance has been accounted for by subtracting the working distance from the
spherical portion of the findings.
A ray of light traveling in water (n=1.33) strikes a flat, transparent surface (n= 1.59) at an angle
of 32 degrees from the normal. What is the angle of refraction? correct answers Snell's law of
refraction states that when light travels through a material that possesses an index of refraction
greater than 1.0, the light rays change direction and become bent (or refracted). Snell's law is
depicted as the following: n sin i= n' sin i' where n= the index of refraction of the first medium,
i= the angle of incidence, n'= the index of the second medium, and i' = the angle of the refracted
ray. All angles are measured with respect to the normal, which lies perpendicular to the interface
between the different media. For the above example, 1.33(sin 32)=1.59 sin i', solving for i'=
26.31 degrees. It is important to commit the index of refraction of water to memory; it is 1.33.
A central retinal artery occlusion (CRAO) causes tremendous damage to the retina. How will the
electroretinogram (ERG) of a person who has suffered a CRAO be affected? correct answers A
central retinal artery occlusion will cause a loss of the b-wave which is formed by responses
from the bipolar and Muller cells, both of which are nourished by the central retinal artery. The
a-wave results from excitation of the photoreceptors. The a-wave will not be lost in the event of a
CRAO due to the fact that photoreceptors receive their oxygen supply via the choroid.
Free radicals can cause severe damage to tissue. Which of the following electrolytes can function
as an antioxidant in the aqueous? correct answers The aqueous humor contains many electrolytes
including Na+, K+ , Cl-, HCO3-, glucose, lactate, amino acids, and ascorbate. Ascorbate is
found in high concentrations in the aqueous (20x greater when compared to the concentration
found in plasma). Ascorbate can serve as an antioxidant to eradicate free radicals reducing
potential damage from ultraviolet light. Interesting note: the aqueous humor and tears of
uncontrolled diabetics display higher levels of glucose than those of non-diabetics.
A 12-year old male is sitting in your waiting room while his mother undergoes her annual eye
exam. While waiting, he eats a candy bar containing peanuts, and, as luck would have it, he is
,deathly allergic to nuts. To counter anaphylactic shock, what would be the BEST course of
action? correct answers Anaphylactic shock is defined as a severe, multi-system, type I
hypersensitive, acute allergic reaction that may be life-threatening. Signs of an allergic reaction
include tingling, itching, hives, swelling of lips and tongue, constriction of the airway,
vasodilation, myocardial depression, and a decrease in blood pressure. The EpiPen is injected
intramuscularly to the upper lateral thigh to ensure rapid delivery. Epinephrine (Adrenaline)
activates both alpha and beta adrenergic receptors causing an increase in peripheral vascular
resistance and allowing for an increase in blood pressure and coronary artery perfusion.
Adrenaline also serves to reverse vasodilation and decrease urticaria and angioedema. For
severe, life-threatening reactions, Benadryl (diphenhydramine) will not work quickly enough.
Topical antihistamines have little if any systemic absorption and therefore will not be effective in
counteracting the anaphylaxis. While oral steroids may be useful in the post-management of
anaphylactic shock, they will not yield the desired immediate response.
An elderly patient presents in your office with decreased visual acuity. He remarks that he can
read better without his glasses and his refraction denotes a large myopic shift. Dilated fundus
exam is unremarkable. Which of the following slit lamp findings would MOST likely explain the
above findings?
Bilateral corneal arcus
Bilateral limbal girdle of Vogt
Bilateral 3+ nuclear sclerosis of the lens
Bilateral crocodile shagreen correct answers Nuclear sclerosis is caused by changes to the optical
clarity of the lens. As we age, proteins precipitate out of the lens matrix, causing the lens to
become cloudy and altering its density. As time passes, the lens will also begin to change color
from clear to a yellow/brown in a process called lens brunescence. Cataracts also generally cause
a myopic shift with an increase in against-the-rule astigmatism, leading to decreased distance
vision but improved near vision.
Corneal arcus is caused by lipid deposition in the peripheral cornea. There remains a
characteristic clear zone between the lipid and the limbus. Arcus does not generally interfere
with vision.
Crocodile shagreen and limbal girdle of Vogt are also benign corneal findings commonly seen in
the elderly. Crocodile shagreen appears in the peripheral cornea as polygonal white opacities.
Limbal girdle of Vogt is noted at the 3 o'clock and 9 o'clock interpalpebral positions as white
crescent-shaped opacities.
Long-term use of corticosteroids can lead to the formation of which of the following types of
cataract?
Nuclear sclerotic
Posterior subcapsular
Cortical
Anterior subcapsular correct answers The possible formation of posterior subcapsular cataracts
(PSC) is a common concern in patients undergoing long-term treatment with corticosteroid
therapy. PSCs have been associated with the use of systemic, topical, ophthalmic, topical
, dermatologic, nasal aerosol, and inhalation type steroids. This relationship is likely dose-
dependent, and the usual time from beginning steroid treatment to the onset of lens changes is 1
year (with a dosage of 10 mg/day of prednisone) but has been observed in as short as 2 months
with as little as 5 mg/day. Patients with PSC formation may complain of an increase in light
sensitivity, photophobia, glare, or difficulty reading. If visual acuity is notably decreased,
surgical removal of the lens may be warranted.
Berger's space is created by an interval between which two structures?
The posterior surface of the cornea and the anterior face of the iris
The anterior face of the lens and the posterior surface of the iris
The equator of the lens and the ciliary body
The posterior face of the lens and the anterior vitreous correct answers Berger's space is created
by the separation between the posterior face of the lens and the anterior face of the vitreous.
The space between the equator of the lens and the ciliary body is known as the circumlental
space.
Patients with a history of homocystinuria are MOST likely to experience crystalline lens
subluxation in which of the following directions?
Down and outward
Up and outward
Down and inward
Up and inward correct answers Common ocular sequelae that have been associated with a
diagnosis of homocystinuria include ectopia lentis (bilateral crystalline lens subluxation), retinal
detachment, and secondary glaucoma. In most cases of ectopia lentis, the lens is more likely to
be displaced downward and inward in homocystinuria (as compared to upward and outward in
Marfan's syndrome). Additionally, in homocystinuria, the lens zonules are markedly abnormal,
the lens does not accommodate, and up to 1/3 of the cases of lens subluxation eventually
completely dislocate into the vitreous or anterior chamber. Due to the severity of systemic and
cardiovascular complications associated with homocystinuria (thrombosis and occlusion),
patients presenting with ectopia lentis should be screened for this disease using the sodium
nitroprusside test to measure homocysteine in the urine.
Purkinje images are caused by reflections of objects on the cornea and lens. Which of the four
images moves forward with accommodation?
III
I
II
IV correct answers There are four Purkinje images. The first image is caused by reflection from
the anterior corneal surface and is the brightest of the images. The first image is roughly the
same size as the object. The second Purkinje image is formed by the posterior surface of the
cornea and almost coincides with the first Purkinje image. The third Purkinje image is the largest
and is caused by reflection off of the anterior plane of the crystalline lens. The fourth Purkinje
image is the smallest and is inverted, formed by reflection off of the posterior surface of the lens.
A 32-year old female is seen at your office complaining of a recent onset of blurred vision, only
at a distance. A thorough case history reveals that she recently began taking a new medication
which you correctly assume has induced myopia. Which of the following medications is MOST
likely to be the culprit? correct answers Isotretinoin, birth control pills, and diuretics, among
many other drugs, can cause myopia in some patients. Myopia mostly likely results from corneal
swelling, which steepens the curvature of the cornea. Drugs that cause swelling of the lens,
accommodative spasm, or edema of the ciliary body will also result in myopia. A reduction in
the dose of the medication or cessation of the offending drug will usually result in reversal of
nearsightedness. Fish oil, Tylenol, and Tums have not been shown to have a correlation with
transient myopia development.
An increased rate of molecular movement down its respective concentration gradient via help
from carrier proteins refers to which type of transportation? correct answers Facilitated diffusion
is described as the net movement of molecules down its concentration gradient whose rate of
diffusion is increased via the use of carrier proteins. Passive diffusion refers to the movement of
molecules through a plasma membrane from an area of high concentration to an area of low
concentration without the use of carrier molecules. Active transport implies the movement of
material against its respective concentration gradient. This type of transport requires energy and
enlists the use of specific carrier proteins. Lastly, group translocation is defined as the chemical
modification of a molecule while it is being transported into a cell; for example, sugars are often
phosphorylated during transportation.
A 24-year old female patient presents at your office complaining of side effects that began when
she started using Patanol to treat her ocular allergies. She reports complete compliance with her
eye drop administration. Which of the following symptoms is MOST likely associated with
olopatadine (Patanol) use? correct answers Topical antihistamines and mast cell stabilizers such
as Patanol (olopatadine) are commonly prescribed to relieve the symptoms associated with
ocular allergies. They are a very effective class of medication due to their dual action
mechanisms. Topical antihistamines that possess this dual action are olopatadine (Patanol),
ketotifen fumarate (Zaditor), azelastine (Optivar), and epinastine (Elestat). The aforementioned
drops serve to alleviate itching and redness by blocking H1 receptors as well as inhibiting mast
cell and basophil degranulation. Side effects of topical antihistamine/mast cell stabilizers include
stinging upon instillation, headaches, and adverse taste (don't forget to inform your patients
about punctual occlusion!). Tachycardia, depression, gastrointestinal discomfort, and visual
hallucinations have not been reported with Patanol use.
A 63-year old female is seen at your office with a chief concern of blurry vision in the morning
that takes about an hour to resolve before she can see clearly again. Biomicroscopy reveals
endothelial guttata. You correctly diagnose her with moderate Fuch's dystrophy. Which
ophthalmic drop would be of MOST benefit to her? correct answers Sodium chloride is a topical
hyperosmotic agent used to relieve stromal edema caused by endothelial decompensation.
Topical steroids work well to decrease swelling caused by inflammation. In the above case, the
corneal edema is not mitigated by an inflammatory response. Tobramycin and Vigamox would
,be of no benefit since there is no active infection, and prescribing either of these would only lead
to corneal toxicity or increased pathogen resistance over time.
A deficiency of which vitamin leads to prolonged dark adaptation? correct answers A deficiency
of vitamin A causes prolonged dark adaptation. Vitamin A is classified as a retinoid, and its
active form is retinol. Retinol is necessary for the formation of rhodopsin, a pigment used by
rods. Rods are most active in situations with dim illumination. Less rhodopsin results in fewer
rods being able to respond in low levels of light, causing prolonged dark adaption.
+1.50-1.50 x 090 is required to neutralize a reflex in retinoscopy with a working distance of 50
cm. What is the resulting NET retinoscopy finding? correct answers A working distance of 50
cm creates a divergent wave of 2.00 D that is neutralized by retinoscopy in addition to the
patient's refractive error. Therefore, + 2.00 D must be subtracted from the spherical portion of
the findings. To determine how much to subtract from the gross findings, one must first calculate
the reciprocal of the working distance in meters. In our case, 1/0.5 = 2. Therefore +1.50 (the
spherical gross findings) -2 = -0.50-1.50 x 090. Remember NET is the final result, this is found
after the working distance has been accounted for by subtracting the working distance from the
spherical portion of the findings.
A ray of light traveling in water (n=1.33) strikes a flat, transparent surface (n= 1.59) at an angle
of 32 degrees from the normal. What is the angle of refraction? correct answers Snell's law of
refraction states that when light travels through a material that possesses an index of refraction
greater than 1.0, the light rays change direction and become bent (or refracted). Snell's law is
depicted as the following: n sin i= n' sin i' where n= the index of refraction of the first medium,
i= the angle of incidence, n'= the index of the second medium, and i' = the angle of the refracted
ray. All angles are measured with respect to the normal, which lies perpendicular to the interface
between the different media. For the above example, 1.33(sin 32)=1.59 sin i', solving for i'=
26.31 degrees. It is important to commit the index of refraction of water to memory; it is 1.33.
A central retinal artery occlusion (CRAO) causes tremendous damage to the retina. How will the
electroretinogram (ERG) of a person who has suffered a CRAO be affected? correct answers A
central retinal artery occlusion will cause a loss of the b-wave which is formed by responses
from the bipolar and Muller cells, both of which are nourished by the central retinal artery. The
a-wave results from excitation of the photoreceptors. The a-wave will not be lost in the event of a
CRAO due to the fact that photoreceptors receive their oxygen supply via the choroid.
Free radicals can cause severe damage to tissue. Which of the following electrolytes can function
as an antioxidant in the aqueous? correct answers The aqueous humor contains many electrolytes
including Na+, K+ , Cl-, HCO3-, glucose, lactate, amino acids, and ascorbate. Ascorbate is
found in high concentrations in the aqueous (20x greater when compared to the concentration
found in plasma). Ascorbate can serve as an antioxidant to eradicate free radicals reducing
potential damage from ultraviolet light. Interesting note: the aqueous humor and tears of
uncontrolled diabetics display higher levels of glucose than those of non-diabetics.
A 12-year old male is sitting in your waiting room while his mother undergoes her annual eye
exam. While waiting, he eats a candy bar containing peanuts, and, as luck would have it, he is
,deathly allergic to nuts. To counter anaphylactic shock, what would be the BEST course of
action? correct answers Anaphylactic shock is defined as a severe, multi-system, type I
hypersensitive, acute allergic reaction that may be life-threatening. Signs of an allergic reaction
include tingling, itching, hives, swelling of lips and tongue, constriction of the airway,
vasodilation, myocardial depression, and a decrease in blood pressure. The EpiPen is injected
intramuscularly to the upper lateral thigh to ensure rapid delivery. Epinephrine (Adrenaline)
activates both alpha and beta adrenergic receptors causing an increase in peripheral vascular
resistance and allowing for an increase in blood pressure and coronary artery perfusion.
Adrenaline also serves to reverse vasodilation and decrease urticaria and angioedema. For
severe, life-threatening reactions, Benadryl (diphenhydramine) will not work quickly enough.
Topical antihistamines have little if any systemic absorption and therefore will not be effective in
counteracting the anaphylaxis. While oral steroids may be useful in the post-management of
anaphylactic shock, they will not yield the desired immediate response.
An elderly patient presents in your office with decreased visual acuity. He remarks that he can
read better without his glasses and his refraction denotes a large myopic shift. Dilated fundus
exam is unremarkable. Which of the following slit lamp findings would MOST likely explain the
above findings?
Bilateral corneal arcus
Bilateral limbal girdle of Vogt
Bilateral 3+ nuclear sclerosis of the lens
Bilateral crocodile shagreen correct answers Nuclear sclerosis is caused by changes to the optical
clarity of the lens. As we age, proteins precipitate out of the lens matrix, causing the lens to
become cloudy and altering its density. As time passes, the lens will also begin to change color
from clear to a yellow/brown in a process called lens brunescence. Cataracts also generally cause
a myopic shift with an increase in against-the-rule astigmatism, leading to decreased distance
vision but improved near vision.
Corneal arcus is caused by lipid deposition in the peripheral cornea. There remains a
characteristic clear zone between the lipid and the limbus. Arcus does not generally interfere
with vision.
Crocodile shagreen and limbal girdle of Vogt are also benign corneal findings commonly seen in
the elderly. Crocodile shagreen appears in the peripheral cornea as polygonal white opacities.
Limbal girdle of Vogt is noted at the 3 o'clock and 9 o'clock interpalpebral positions as white
crescent-shaped opacities.
Long-term use of corticosteroids can lead to the formation of which of the following types of
cataract?
Nuclear sclerotic
Posterior subcapsular
Cortical
Anterior subcapsular correct answers The possible formation of posterior subcapsular cataracts
(PSC) is a common concern in patients undergoing long-term treatment with corticosteroid
therapy. PSCs have been associated with the use of systemic, topical, ophthalmic, topical
, dermatologic, nasal aerosol, and inhalation type steroids. This relationship is likely dose-
dependent, and the usual time from beginning steroid treatment to the onset of lens changes is 1
year (with a dosage of 10 mg/day of prednisone) but has been observed in as short as 2 months
with as little as 5 mg/day. Patients with PSC formation may complain of an increase in light
sensitivity, photophobia, glare, or difficulty reading. If visual acuity is notably decreased,
surgical removal of the lens may be warranted.
Berger's space is created by an interval between which two structures?
The posterior surface of the cornea and the anterior face of the iris
The anterior face of the lens and the posterior surface of the iris
The equator of the lens and the ciliary body
The posterior face of the lens and the anterior vitreous correct answers Berger's space is created
by the separation between the posterior face of the lens and the anterior face of the vitreous.
The space between the equator of the lens and the ciliary body is known as the circumlental
space.
Patients with a history of homocystinuria are MOST likely to experience crystalline lens
subluxation in which of the following directions?
Down and outward
Up and outward
Down and inward
Up and inward correct answers Common ocular sequelae that have been associated with a
diagnosis of homocystinuria include ectopia lentis (bilateral crystalline lens subluxation), retinal
detachment, and secondary glaucoma. In most cases of ectopia lentis, the lens is more likely to
be displaced downward and inward in homocystinuria (as compared to upward and outward in
Marfan's syndrome). Additionally, in homocystinuria, the lens zonules are markedly abnormal,
the lens does not accommodate, and up to 1/3 of the cases of lens subluxation eventually
completely dislocate into the vitreous or anterior chamber. Due to the severity of systemic and
cardiovascular complications associated with homocystinuria (thrombosis and occlusion),
patients presenting with ectopia lentis should be screened for this disease using the sodium
nitroprusside test to measure homocysteine in the urine.
Purkinje images are caused by reflections of objects on the cornea and lens. Which of the four
images moves forward with accommodation?
III
I
II
IV correct answers There are four Purkinje images. The first image is caused by reflection from
the anterior corneal surface and is the brightest of the images. The first image is roughly the
same size as the object. The second Purkinje image is formed by the posterior surface of the
cornea and almost coincides with the first Purkinje image. The third Purkinje image is the largest
and is caused by reflection off of the anterior plane of the crystalline lens. The fourth Purkinje
image is the smallest and is inverted, formed by reflection off of the posterior surface of the lens.
