#Ophthalmic lens #Spectacle Lenses #Lenses (Sph+Cyl) #IOLs #Enchroma Glass #Unifocal/Bifocal/Trifocal/PALs

1. Ophthalmic Lenses
Md.Azizul Islam
Associate Optometrist
Ispahani Islamia Eye Institute & Hospital
IIEI&H

2. Lenses are transparent objects
that bend (or 'refract') light by
virtue of the curvature of their
outer surface. Although they may
sometimes look flat, all lenses
have some convex or concave
curvature, which is what causes
them to have an optical effect.
Lenses
 Lenses can be of six different types :
1. Biconvex lens - both sides are convex
2. Plano-convex lens - one side is plane, the other side is convex
3. Meniscus lens - convex meniscus: meniscus shaped with greater convex curvature
4. Biconcave lens - both sides are concave
5. Plano-concave lens - one side is plane and other side is concave
6. Meniscus lens - concave meniscus: meniscus with greater concave curvature IIEI&H

3.  An ophthalmic lens is a lens for correcting
vision in a person with visual impairments
where the focal point of the eyes does not hit
the retina. Lenses can also be used to address
problems like astigmatism. They come in a
variety of forms including plastic and glass
lenses worn in glasses, contact lenses placed in
direct contact with the eye, and lens implants
surgically inserted into the eye to correct visual
impairments.
 It is usually necessary to receive a prescription
for a specific ophthalmic lens, although some
people can correct their vision with over-the-
counter lenses.
Ophthalmic Lenses
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4. A Spectacle Lenses is a lens typically
worn in front of the eye to improve
vision. The most common use is to treat
refractive errors: myopia,
hypermetropia, astigmatism, and
presbyopia. Spectacles" are worn on the
face a short distance in front of the eye.
Spectacle Lenses
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5. Two principal types of spectacle lenses lenses are
manufactured to correct vision:
 Single-vision lenses, which provide correction for
only one distance (that is, far or near).
 Multifocal lenses (bi-focals, trifocals, and
progressive-addition lens). which combine two or
more corrections in a single lens to provide sharp
vision at more than one distance.
Type Of Spectacle Lenses
Distance
Near
IIEI&H

6. This lens provides correction only for
a given distance. This means that the
optical power is the same at every
point on the lens’s surface.
Prescribed only for single vision.
 Distance vision glass
 Near vision glass
 Vocational glass
Single vision Or Unifocal Lenses
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7. In presbyopic cases you need separate power
for distance and near. It is not convenient to
carry two glasses. When you are reading you
will have to take change glasses for distance
vision to see distant objects and vice versa.
Types are :
 Kryptok : suitable for hypermetropic
patients.
 B. Flat top / D shaped : suitable for
myopic patients.
 Executive : Best for pseudophakic
paediatric patients and also for
presbyopic patients as well.
Bifocals Lenses
Distance
Near
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8. Trifocals Lenses
Trifocals are eyeglasses with lenses
that have three regions which
correct for distance, intermediate
(arm's length), and near vision. John
Isaac Hawkins developed the
trifocal lens in 1827. Trifocals are
mostly used by people with
advanced presbyopia who have been
prescribed 2 diopters or more of
reading addition.
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9. In these cases the lens has multiple
power to cover all distances as power
changes progressively. It thus gives good
vision for all distances.
Further there is no demarcation line
giving better look.
 Hard Design
 Soft Design
Multifocals / Progressive Lenses
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10. Refractive index: Increasing the refractive index reduces the volume of lens
making lens flatter. In minus lenses it reduces edge thickness and in plus
lenses it reduces central thickness. The lenses with higher index is known
as Hi Index lens.
 Normal index: 1.48 ≤ nd < 1.54
 Mid-index: 1.54 ≤ nd < 1.60
 High-index: 1.60 ≤ nd < 1.74
 Very high index: 1.76 ≤ nd
 Specific Gravity: It is density or weight of lens per cubic cm. High Index
lenses are heavier because of high specific gravity but reduced volume
compensates for increased weight. Material density typically increases as
lens thickness is reduced by increasing index.
Features of Lenses
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11.  Glass lenses : This is the most common used lens.
 Advantages:
 Scratch Resistance
 Longer Durability
 Clarity over Time
 Precise Light Distribution
 Plastic lenses: Plastic lenses has lesser refractive
index than glass and specific gravity is more than
glass.
 Advantages:
 Unlike glass which can be very heavy in frames, plastic is much
lighter.
 Any photochromic tints can be applied to a plastic lens.
 Polarized tints can also be applied using plastic lenses.
 Plastic lenses are very durable.
Type Of Spectacle Lenses Materials
IIEI&H

12.  Advantages:
 Impact Resistant.
 Thinner than glass lenses.
 Lighter weight.
 Built in U V protection.
Polycarbonate lenses: are resilient, impact-resistant and a favorite among
active individuals. The durability of polycarbonate lenses makes them a
good choice for rimless eyeglasses. Plus, polycarbonate lenses have built-
in UV filters to help prevent eye problems such as macular degeneration
(breakdown of macula) and cataracts (clouding of the eye lens).
Polycarbonate lenses are up to 10 times more impact-resistant than
plastic or glass lenses and they provide 100% protection from the sun's
harmful UV rays.They are also lightweight, adding to the comfort of your
eyeglasses, sunglasses, and sports eyewear.
Type Of Spectacle Lenses Materials
IIEI&H

13. Trivex Lenses: Despite its many advantages,
polycarbonate isn't the only lens material suitable
for safety applications and children's eyewear. In
2001, PPG Industries (Pittsburgh, Penn.)
introduced a rival lens material called Trivex. Like
polycarbonate lenses, lenses made of Trivex are
thin, lightweight and much more impact-resistant
than regular plastic or glass lenses.
Trivex lenses, however, are composed of a
urethane-based monomer and are made from a
cast molding process similar to how regular plastic
lenses are made. This gives Trivex lenses the
advantage of crisper optics than injection-molded
polycarbonate lenses.
Trivex lenses are lightweight
and resist cracking, making
them a great choice for rimless
frames. This one is by
Silhouette International.
Type Of Spectacle Lenses Materials
IIEI&H

14. Anti Reflection Coating: It is a coating given on
the surface of the lens ,which could be of plastic
or glass base.The compound used is mostly
Magnesium base oxides and fluorides in some
cases.
The purpose of this coating is to cut off
unwanted reflections and glare from different
sources thus enhancing visual also enhances the
cosmetic appeal of the person.
Type Of Spectacle Lenses Other
Options/Coating
Normal
ARC
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15. Hard Multi Coating: This is an 8 layered
combination of multiple coating given principally to
the plastic lenses.This coating comprises
antireflection coating, the scratch resistant coating ,
the top hydrophobic coat (which prevents water
getting smudged on the surface of the lens) and
zirconium oxide coating to increase the toughness of
the lens.
U.V.Protection: This property can be increased by
some additives.
Scratch Resistance Coating: Reduces the scratches in
plastic lenses.
Type Of Spectacle Lenses Other
Options/Coating
IIEI&H

16. Type Of Spectacle Lenses Other
Options/Coating
Polarized Lenses ( Anti Glare): Polarized lenses reduce
glare reflected off surfaces, making images appear
sharper and clearer.They are available for non-
prescription and prescription sunglasses, and can be
worn indoors by light-sensitive people, including post-
cataract surgery patients and those continually exposed
to bright sunlight through windows. Most polarized
lenses provide UV protection, which is important to
maintaining healthy eye sight.
IIEI&H

17. Photochromic Lenses: Becomes dark
colored in bright light, so act as sunglasses and
U.V.Protecter.
Infrared Blocking lenses: Infrared wavelengths
are not known to cause any harm to eye so these
glasses are of no known advantage.Blue
blocking lenses: Lenses that block blue light are
usually amber colored and make the
surroundings look yellow or orange. The tint
makes distant object appear clearer, especially
in snow and haze. These are good for skiers ,
hunters, boaters and pilots.
Type Of Spectacle Lenses Other
Options/Coating
IIEI&H

18. Benefits :
 Transmits all colors evenly
 Good for general purpose use
 Dims glare while brightening
shadows
 Sport/Activity
 All outdoor activities
 Weather Conditions.
Tinted Lenses: Colored or tinted sunglasses come in and out of style all
the time. But as well as complimenting your summer threads, lens tints
serve a variety of important purposes. A good tinted lens protects your
eyes against UV radiation.They can also give you a high-contrast vision
experience even in glaring or diffuse light.
Type Of Spectacle Lenses Other
Options/Coating
IIEI&H

19. Blue-light reduction lenses: Blue-light reduction is a
next-generation lens coating that combats digital eye
strain by reducing your exposure to blue light from
smartphones, tablets, computer screens, televisions,
energy-efficient lighting, and the sun.This attractive,
near-clear coating also optimizes visual performance,
improves visual comfort, enhances your appearance,
and extends the life of your lenses. Used mostly for
computer using.
Type Of Spectacle Lenses Other
Options/Coating
IIEI&H

20. Anti-fog coating lenses :Anti-fog agents, also
known as anti-fogging agents and treatments,
are chemicals that prevent the condensation of
water in the form of small droplets on a surface
which resemble fog .The treatments work by
minimizing surface tension, resulting in a non-
scattering film of water instead of single
droplets.
This works by altering the degree of wetting.
Anti-fog treatments usually work either by
application of a surfactant film, or by creating a
hydrophilic surface.
Type Of Spectacle Lenses Other
Options/Coating
IIEI&H

21. Star night vision glasses: Anti-glare UV400
protected polarized HD night vision glasses
for safe night driving and ultra enhanced
vision, lightweight frame with stylish.
 Composite lens
 Polarized
 Scratch resistant coating coating
 Lenses--polarized yellow lens, anti-glare
coatings and ultra-pure lens; shatterproof
,impact and scratch resistant, lightweight
and durable
Type Of Spectacle Lenses Other
Options/Coating
IIEI&H

22. EnChroma color-blind glasses: Color-blind glasses
are eyeglasses with lenses that have special filters
to help a person with color-blindness see colors
more accurately.
Though color-blind glasses will not "cure" color-
blindness, they give color-blind individuals an
opportunity to see the world more accurately and
experience a greater spectrum of colors while
wearing the glasses.
Color-blind glasses also have very practical
applications, such as helping a color-blind person
choose and match the colors and patterns of their
clothes (reducing the risk of odd color choices and
mismatched colors).
Type Of Spectacle Lenses Other
Options/Coating
IIEI&H

23. Trial Lens
 During refraction the practitioner utilize a set of
known lenses called as Trial lenses.
FULL APERTURE LENSES : Approximately 38 mm
diameter . Biconvex or biconcave form .
 REDUCED APERTURE LENSES :Lenses of 20 mm
diameter mounted in the metal rim of 38 mm
diameter. It also Biconvex or biconcave form .
Types of Trial Lenses
 Plano lenses
 Spherical lenses
 Cylindrical lenses
 Prism Lenses IIEI&H

24. A corrective lens with a power of zero is called a plano
lens. These lenses are used when one or both eyes do
not require correction of a refractive error. Some
people with good natural eyesight like to wear
eyeglasses as a style accessory, or want to change the
appearance of their eyes using novelty contact lenses.
Many individuals wear eyeglasses having lenses with
no visual correcting power, called “plano lenses,” to
project an image, make a fashion statement or
complement their wardrobe. Tinted plano glasses can
be used by hobbyists to improve their vision
Plano Lens
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25.  All meridians have same power.There are (±) 32/40
pairs of spherical lens in plus & minus power.
Spherical Lenses
Use of Spherical Lenses
 For spherical ametropia
 For hand neutralization
 Checking the refracting error
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26.  Power lies in one meridian. Axis meridian is marked on
rim of the lenses. (±) 20 pairs of CYL Lenses.
Cylindrical Lenses
Use of Cylindrical Lenses
 For hand neutralization
 For correction of astigmatism
 For checking the refractive error
IIEI&H

27. Prism is a refractive medium having two plane surfaces
inclined at an angle. Principle :- “1 prism diopters
produces displacement of the image at 1 cm when the
object is situated at the distance at 1m.” Its For the
measurement and correction of the angle of deviation &
Correct & measure Strabismus . 10 /12 pcs
Power range of :
½(0.5)D
1- 6.00D in 1D steps
6- 12.00D in 2D steps
Prism Lenses
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28.  Anterior Chamber Intraocular Lens.
 Posterior chamber intraocular lenses
(PCIOL) are placed within the capsular
bag or less commonly anchored into
the ciliary sulcus. The lens can be
folded and inserted into the eye
through a very small opening made
during phacoemulsification or SICS.
IOLs/ACIOL/PCIOL
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29. Multifocal and Accommodating
intraocular lenses are artificial
intraocular lenses (IOLs) that are
designed to provide focus of both
distance and near objects, in
contrast to monofocal intraocular
lenses which only have one focal
point and correct distance vision.
Multifocal IOLs
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30. Contact Lenses
Contact lens, or simply contacts, are thin lenses placed
directly on the surface of the eyes. Its Very thin piece of
specialized plastic that can alter the optical power of the
externally.
Insertion and removal takes seconds.
Very comfortable-fitting is specialized.
Prescribed by optometrists and ophthalmologists..
Advantage :
 Wider field of view
 Better with asymmetrical prescriptions
 Better for vary high prescription
 Cosmetically superior
 More practical for sports IIEI&H

31. THANKS-ALL