NCLE basic Exam kit| 360 QUESTIONS| WITH COMPLETE SOLUTIONS
What is the Secondary/intermediate curve? Correct Answer: The curve on the posterior side of
the contact lense between the base curve and peripheral curve. Usually 0.7mm to 1.6mm flatter
than the base curve radius. The width is affected by the OZ diameter and peripheral width.
What is the peripheral curve? Correct Answer: The outermost curve on the posterior side of the
contact lens. It clears the flatter periphery and prevents lens impingement in the limbal areas
What measurements effect the size of the peripheral curve? Correct Answer: The radius of
curvature and width.
Smaller diameter = steeper radius of curve
Larger diameter = flatter radius of curve
What is a blend curve? Correct Answer: A treatment given to sharp junctions caused by
differences in radii of curvature. Mostly required between secondary and peripheral curve.
Blended curve = secondary and peripheral average
What is the diameter of the contact? Average diameter of an RGP lens? Correct Answer: The
overall width of lenses from end to end in mm.
RGP average is 7mm to 10.5mm
What is the anterior optical zone radius of curvature Correct Answer: The radius of curvature of
the front surface. It determines the refractive power of the lens. Has both a radius and diameter.
How do you determine the lens power? Correct Answer: The difference between the radio of
anterior and posterior surfaces. Anterior - posterior
What is the base curve? Correct Answer: The radius of curvature of the central posterior surface
of contact lenses. Measures in diopters or mm
What is the OZ? Correct Answer: The diameter of the base curve on the posterior of the contact
lens in mm
What is a lenticular flange? Correct Answer: An increase or decrease in anterior edge thickness
to change the lens mass or help with the positioning
What is the myoflange design? Correct Answer: An increase in anterior edge thickness that aids
in better centering lenses that sit low on the cornea. Thicker = more kid interaction. The upper lid
holds the lens higher
What is the hyperflange or CN bevel design? Correct Answer: A decrease in anterior edge
thickness in high minus lenses to limit lid interaction. Allows lens to position more centrally on
the cornea
,Lenticular flange steeper radius vs. flatter radius Correct Answer: Radius between 1.5mm to
2.2mm
Steeper (1.7mm) edge is too thick and lens rises high
Flatter (2.2mm) edge too thin and lid control is lost
About the lens edge Correct Answer: Has 3 zones. It is the most peripheral part of the lens. The
junction of posterior and anterior. Designed to limit adverse lid irritation during blinking. Helps
keep posterior surface away from the cornea.
Anterior zone of lens edge Correct Answer: Part of the edge in contact with the upper lid during
the blink cycle. Minimizes lid irritation during blinking
Posterior zone of the lens edge Correct Answer: Small reverse curve on the posterior surface to
flare the edge away from the cornea. Allows free movement of the lens across the cornea during
eye excursions and for lens removal using scissor blink technique. Also allows lens to be safely
centered on cornea when it dislocates.
Edge apex of the lens edge Correct Answer: Junction between anterior and posterior zones.
Must be well rounded to minimize lid awareness during blink
Prism ballast Correct Answer: Adding plastic to the anterior surface. Adds weight to the lens
and gives it proper orientation of some astigmatism and bifocal designs
What is the watermelon seed effect? Correct Answer: The prism ballast takes place throughout
the squeezing action of the upper lid which forces the lens downward. The more thickness let's
lower lid force upward during downgaze. Happens with bifocals too.
What is truncation? Correct Answer: The removal of the inferior and/or superior parts of the
lens to aid in meridional orientation and stabilization. This can be done with front toric or bifocal
lenses.
Spherical lens design Correct Answer: The radius of curvature is the same in every meridian of
each lens surface. The lens remains spherical even though the radius is different on each surface
The front surface toric design Correct Answer: Has a spherical posterior surface with a toric
anterior curve. Usually needs a prism ballast to keep in place
Back surface toric design Correct Answer: Toric posterior curve with 2 different principle
meridians 90 degrees apart. Anterior side is spherical. Controls rotation with more than 2
diopters of corneal astigmatism. Only works when refractive cylinder is 1/3 more than the
corneal astigmatism because there is increased power transferred to the front of the contact.
Bitoric lens design Correct Answer: Has toric curves on both surfaces with the principle
meridians 90 degrees apart. Used to improve lens position for high astigmatism. Also corrects
any residual refractive component.
, What is K? Correct Answer: The flattest of the primary meridians measured by keratometry
Sagittal depth Correct Answer: The distance between the central area and the flat surface on the
posterior surface.
Adnexa Oculi Correct Answer: The accessory structures of the eye. Includes eyelids, eyelashes,
lacrimal apparatus and conjunctiva
Functions of the eyelids Correct Answer: Distributes tears over the anterior part of the eye and
limits the amount of light that enters the eye
Palpebral fissure Correct Answer: An opening formed by the eye lid margins
28-30mm horizontally by 14-15mm vertically in adults.
Canthi Correct Answer: The junctions of the upper and lower lid margins.
Lateral canthus Correct Answer: Outer canthus, forms an acute angle
Medial canthus Correct Answer: inner corner of the eye where the upper and lower eyelids
meet. Rounded
Caruncle Correct Answer: Small mound of skin found at the medial canthus. Contains sweat and
sebaceous glands. Appears as a yellowish elevation.
Semilunar fold Correct Answer: Lateral to the caruncle. A vestigial remnant of the third eyelid
of lower animal species.
Epicanthus Correct Answer: A vertical fold of skin extending from the upper to lower lid. Can
be seen in infants. Disappears with development except in Asian races where it remains and
forms the almond shaped eye.
Puncta Correct Answer: An opening that drains tears from the eye about 5mm from the inner
canthus along the upper and lower lid margins.
Thickness of lid margins Correct Answer: 2mm thick. Divided into inner and outer halves by the
gray line
What is behind and in front of the grey line? Correct Answer: Behind are the meibomian glands
and in front are the eyelashes (cilia)
Sulcus Correct Answer: The part of the eyelid that separates the orbital portion of the lid from
the tarsal portion extending up to the eyebrow
The 4 layers of the eyelid Correct Answer: Skin, orbicularis oculi muscle, orbital spectrum,
palpebral conjunctiva
What is the Secondary/intermediate curve? Correct Answer: The curve on the posterior side of
the contact lense between the base curve and peripheral curve. Usually 0.7mm to 1.6mm flatter
than the base curve radius. The width is affected by the OZ diameter and peripheral width.
What is the peripheral curve? Correct Answer: The outermost curve on the posterior side of the
contact lens. It clears the flatter periphery and prevents lens impingement in the limbal areas
What measurements effect the size of the peripheral curve? Correct Answer: The radius of
curvature and width.
Smaller diameter = steeper radius of curve
Larger diameter = flatter radius of curve
What is a blend curve? Correct Answer: A treatment given to sharp junctions caused by
differences in radii of curvature. Mostly required between secondary and peripheral curve.
Blended curve = secondary and peripheral average
What is the diameter of the contact? Average diameter of an RGP lens? Correct Answer: The
overall width of lenses from end to end in mm.
RGP average is 7mm to 10.5mm
What is the anterior optical zone radius of curvature Correct Answer: The radius of curvature of
the front surface. It determines the refractive power of the lens. Has both a radius and diameter.
How do you determine the lens power? Correct Answer: The difference between the radio of
anterior and posterior surfaces. Anterior - posterior
What is the base curve? Correct Answer: The radius of curvature of the central posterior surface
of contact lenses. Measures in diopters or mm
What is the OZ? Correct Answer: The diameter of the base curve on the posterior of the contact
lens in mm
What is a lenticular flange? Correct Answer: An increase or decrease in anterior edge thickness
to change the lens mass or help with the positioning
What is the myoflange design? Correct Answer: An increase in anterior edge thickness that aids
in better centering lenses that sit low on the cornea. Thicker = more kid interaction. The upper lid
holds the lens higher
What is the hyperflange or CN bevel design? Correct Answer: A decrease in anterior edge
thickness in high minus lenses to limit lid interaction. Allows lens to position more centrally on
the cornea
,Lenticular flange steeper radius vs. flatter radius Correct Answer: Radius between 1.5mm to
2.2mm
Steeper (1.7mm) edge is too thick and lens rises high
Flatter (2.2mm) edge too thin and lid control is lost
About the lens edge Correct Answer: Has 3 zones. It is the most peripheral part of the lens. The
junction of posterior and anterior. Designed to limit adverse lid irritation during blinking. Helps
keep posterior surface away from the cornea.
Anterior zone of lens edge Correct Answer: Part of the edge in contact with the upper lid during
the blink cycle. Minimizes lid irritation during blinking
Posterior zone of the lens edge Correct Answer: Small reverse curve on the posterior surface to
flare the edge away from the cornea. Allows free movement of the lens across the cornea during
eye excursions and for lens removal using scissor blink technique. Also allows lens to be safely
centered on cornea when it dislocates.
Edge apex of the lens edge Correct Answer: Junction between anterior and posterior zones.
Must be well rounded to minimize lid awareness during blink
Prism ballast Correct Answer: Adding plastic to the anterior surface. Adds weight to the lens
and gives it proper orientation of some astigmatism and bifocal designs
What is the watermelon seed effect? Correct Answer: The prism ballast takes place throughout
the squeezing action of the upper lid which forces the lens downward. The more thickness let's
lower lid force upward during downgaze. Happens with bifocals too.
What is truncation? Correct Answer: The removal of the inferior and/or superior parts of the
lens to aid in meridional orientation and stabilization. This can be done with front toric or bifocal
lenses.
Spherical lens design Correct Answer: The radius of curvature is the same in every meridian of
each lens surface. The lens remains spherical even though the radius is different on each surface
The front surface toric design Correct Answer: Has a spherical posterior surface with a toric
anterior curve. Usually needs a prism ballast to keep in place
Back surface toric design Correct Answer: Toric posterior curve with 2 different principle
meridians 90 degrees apart. Anterior side is spherical. Controls rotation with more than 2
diopters of corneal astigmatism. Only works when refractive cylinder is 1/3 more than the
corneal astigmatism because there is increased power transferred to the front of the contact.
Bitoric lens design Correct Answer: Has toric curves on both surfaces with the principle
meridians 90 degrees apart. Used to improve lens position for high astigmatism. Also corrects
any residual refractive component.
, What is K? Correct Answer: The flattest of the primary meridians measured by keratometry
Sagittal depth Correct Answer: The distance between the central area and the flat surface on the
posterior surface.
Adnexa Oculi Correct Answer: The accessory structures of the eye. Includes eyelids, eyelashes,
lacrimal apparatus and conjunctiva
Functions of the eyelids Correct Answer: Distributes tears over the anterior part of the eye and
limits the amount of light that enters the eye
Palpebral fissure Correct Answer: An opening formed by the eye lid margins
28-30mm horizontally by 14-15mm vertically in adults.
Canthi Correct Answer: The junctions of the upper and lower lid margins.
Lateral canthus Correct Answer: Outer canthus, forms an acute angle
Medial canthus Correct Answer: inner corner of the eye where the upper and lower eyelids
meet. Rounded
Caruncle Correct Answer: Small mound of skin found at the medial canthus. Contains sweat and
sebaceous glands. Appears as a yellowish elevation.
Semilunar fold Correct Answer: Lateral to the caruncle. A vestigial remnant of the third eyelid
of lower animal species.
Epicanthus Correct Answer: A vertical fold of skin extending from the upper to lower lid. Can
be seen in infants. Disappears with development except in Asian races where it remains and
forms the almond shaped eye.
Puncta Correct Answer: An opening that drains tears from the eye about 5mm from the inner
canthus along the upper and lower lid margins.
Thickness of lid margins Correct Answer: 2mm thick. Divided into inner and outer halves by the
gray line
What is behind and in front of the grey line? Correct Answer: Behind are the meibomian glands
and in front are the eyelashes (cilia)
Sulcus Correct Answer: The part of the eyelid that separates the orbital portion of the lid from
the tarsal portion extending up to the eyebrow
The 4 layers of the eyelid Correct Answer: Skin, orbicularis oculi muscle, orbital spectrum,
palpebral conjunctiva
