for the students of optometry and other eye care professionals.

1. By- ABHISHEK YADAV
Optometrist
Community ophthalmology

3. Most refractive errors can be corrected with
eyeglasses, contact lenses, or surgery.
Several factors are considered
when choosing a corrective option:
•Age
•Cost
•Individual preference
•Lifestyle
•Occupation
•Other health conditions
•Severity and type of refractive error

4.  A thin plastic lens placed directly on the anterior surface of the eye
to correct visual defects.
 Types of contact lenses: hard lenses, soft lenses, extended-wear
lenses, and disposable lenses.
 Contact lenses are available in soft materials and hard gas-
permeable varieties. All types of contact lenses, including bifocals
and those for astigmatism, are available as disposable and frequent
replacement lenses.

5. Is it still very new...
Barraquar pioneered surgery in 1960
Invented by- JOSH BARRAQUAR
Method- Keratomileusis
HISTORY OF REFRACTIVE Sx

6.  Several surgical procedures can correct refractive errors. The type and degree
of refractive error determines whether or not a patient is a good candidate
for surgery. There are risks involved and favorable outcomes are not
guaranteed.
Types of surgery to correct refractive errors
include:
•Radial keratotomy (RK)
•Photorefractive keratectomy (PRK)
•Astigmatic keratotomy (AK)
•Automated lamellar keratoplasty (ALK)
•Laser thermal keratoplasty (LTK)
•Conductive keratoplasty (CK)
•Intracorneal ring (Intacs)
•Laser in-situ keratomileusis (LASIK)

7. CRITERIA
• Age more than 20 years
• Stable refractive power for at least 6 months
• Last contact lens used 2 weeks in case of soft CL &
4 weeks in case of hard CL before the work up
• Corneal thickness more than 500µ
• Intraocular pressure less than 20 mm of Hg
HISTORY
Type of correction used- spectacle/contact lens
 Need for surgery- cosmetic/professional/ any other
 H/O previous surgery- RK/ AK/ any other
 H/O previous ocular disease/ systemic disease/pregnancy/ ocular drug
 Systemic drugs-

8. Investigation to be done
Visual acuity assessment UCVA, BCVA Snelle’s chart
Routine eye examination Slit lamp examination
Keratometry Manual Keratometry, VKG
Pachymetry Ultrasonic Pachymeter
Contrast sensitivity FACT
Glare acuity Humphery auto-ref.
Color vision Ishihara
Topography
Corneal curvature, Corneal thickness,
Posterior elevation, Belin /Ambrosio
display
Orbscan, Pentacam
Pupil size Mesopic, Photopic
Corneal sensation Aesthesiometer
Corneal diameter Orbscan II
Tear film evaluation Schirmer’s test, BUT
Auto refraction
Refraction under proper cycloplegic Final PMT
Dilated fundus examination Direct ophthalmoscope, Indirect ophthalmoscope
Axial length Lenstar, IOL Master
Applanation tonometry NCT, Goldman applanation tonometer

9.  Radial keratotomy (RK) is a procedure used to correct mild myopia. Tiny
spoke-like (radial) incisions called keratotomies are cut in the cornea with a
diamond scalpel. The incisions cause the center of the cornea (optical zone)
to flatten and changes the curve of the cornea. This reduces refraction.
Because the cornea is cut, it takes several weeks to heal. This surgery was
very common, but has been nearly replaced by LASIK.
Possible complications include:
 Changing vision during the first few months
 Infection
 Discomfort
 A weakened cornea that can rupture
 Trouble fitting contact lenses
 Glare around lights
 Clouding of the lens (cataract)
 Loss of vision

10.  Photorefractive keratectomy (PRK) is done with the same kind of excimer laser used
for LASIK surgery. PRK is done to reshape the cornea to correct mild to moderate
nearsightedness (myopia).
 The excimer laser beam reshapes the cornea by removing tiny amounts of tissue
from the outer surface. The procedure uses a computer to map the eye's surface and
calculate how much tissue to remove. This surgery generally takes a few minutes.
Because the cornea surface is cut, it takes several weeks to heal.
The most common side effects include:
 Eye pain that may last for several weeks
 Mild corneal haze right after surgery
 Glare or halos around lights for months after surgery

11.  Astigmatic keratotomy (AK) is similar to radial keratotomy
(RK). This surgery is used to correct astigmatism. Instead of
making radial incisions, the eye surgeon makes cuts in the
cornea in a curved pattern.

12.  Automated lamellar keratoplasty (ALK) is used for hyperopia and severe
cases of myopia. For myopia, the eye surgeon cuts a flap across the front of
the cornea with a tool called a microkeratome. The flap is folded to the side.
A thin slice of tissue is removed from the surface of the cornea. This flattens
the central cornea (optical zone) and reduces refraction. The flap is then put
back in place. The flap reattaches itself without stitches.
 During ALK for hyperopia, the eye surgeon makes a deeper incision into the
cornea with the microkeratome to create a flap. The pressure in the eye
causes the corneal surface to stretch and bulge. The bulging cornea
improves the optical power. This corrects the hyperopia. The flap is then put
back in place, where it reattaches without stitches.
Possible complications of ALK surgery include:
 Overcorrected or undercorrected vision
 Astigmatism
 Inability to wear contact lenses
 Loss of the corneal flap and need for a corneal graft
 Scarring
 Infection
 Vision loss
 Glare

13.  Laser thermal keratoplasty (LTK) applies heat from a laser to
the edges of the cornea. This shrinks the collagen fibers and
reshapes the cornea. You must be age 40 or older to have
this surgery.

14.  Conductive keratoplasty (CK) is used to correct mild to
moderate hyperopia. It uses heat from low-level radio waves
to shrink the collagen and change the shape of the cornea. A
probe smaller than a strand of hair is used to apply the radio
waves around the outer cornea. This creates a tight band that
increases the curve of the cornea and improves vision. You
must be age 40 or older to have this surgery.

15.  Intracorneal rings (Intacs) are used to treat mild myopia. They
are microthin rings that are implanted into the cornea. Intacs
shape of the curve of the cornea and improve vision.

16.  Laser in-situ keratomileusis (LASIK) is surgery to correct myopia, hyperopia, or
astigmatism. The procedure reshapes the cornea with an excimer laser.
 LASIK surgery is done using a computer-controlled excimer cold laser, and a tool
called a microkeratome or a femtosecond laser. With these tools, the surgeon cuts
a flap in the center of the cornea to remove a thin layer of tissue. This causes the
cornea to flatten. The flap is replaced without stitches and reattaches to the
cornea within minutes.
 In most cases, recovery from LASIK surgery is fast and involves minimal
discomfort. Mild pain medicine and eye drops can help common after-effects of
surgery such as:
 Dry eyes during healing
 Eye discomfort in the first 24 hours after surgery
Possible complications include:
 Overcorrected or under corrected vision
 Irregular astigmatism
 Corneal haze or glare
 Sensitivity to light
 Inability to wear contact lenses
 Loss of the corneal flap and need for a corneal graft
 Scarring
 Infection
 Blurry vision or vision loss

17.  Small incision lenticule extraction
(SMILE) is a relatively new
refractive procedure designed to
treat a multitude of refractive
errors such as myopia, hyperopia,
presbyopia, and astigmatism. The
procedure involves using a
femtosecond laser to create a
corneal lenticule which is extracted
whole through a small incision
without the use of an excimer
laser. It is reported to achieve
effects similar to laser-assisted in
situ keratomileusis (LASIK) with
excellent post-operative
outcomes.
 SMILE laser eye surgery can correct
up to -10.00 diopters (D) of
nearsightedness.

18.  SMILE can only correct nearsightedness, whereas LASIK and
PRK can also correct significant amounts of farsightedness
and astigmatism.
 LASIK and PRK can treat higher-order aberrations (HOAs) that
can affect night vision, whereas SMILE cannot. In fact, SMILE
might increase HOAs to some degree.
 if you have residual refractive error after a SMILE procedure
and require additional vision correction, typically PRK would
be the preferred enhancement procedure for best results.

19.  During the ICL procedure, no corneal tissue is
removed. The lens is inserted through a 3 mm
self-sealing incision where no stitches are
needed.
 An ICL is an artificial lens, similar in function
to a contact lens, which is implanted in front
of the eye’s natural lens but behind the iris so
that it is practically invisible to outside
observers. The ICL procedure corrects
moderate to severe myopia (nearsightedness).
 Widest power correction range from +10D to -
20D with cylinder upto 6D

20. Advantages of ICL
•Preserves accommodation
• No corneal tissue removed
•Retains corneal asphericity
•Possibly retains contrast sensitivity
•Removable
How does the ICL work?
•Similar to a contact lens
• Designed to remain inside the eye
•Doesn't get dirty and needs no maintenance unlike a contact lens
•Once-a-year visit to hospital recommended for examination

21. Superficial procedures
PRK
Range of applicability
•Myopia(–6D to -8D)
•Astigmatism (5D to 6D)
•Hyperopia up to +4D
LASIK
Range of applicability
•Myopia(–8D to -10D)
•Astigmatism(5D to 6D)
•Hyperopia (+3D to +4D)
Phakic IOL
Range of applicability
•Myopia of –8D or more
•Hyperopia of +4D or more
•Astigmatism upto 6D
CCT
AMOUNT OF
REFRACTIVE ERROE
•15µ=1D
•Flap size= 100µ
•Residual bed thickness should
not be less than 280µ
I CCT=500µ, -5D
5*15= 75µ + 100µ=175µ
500µ-175µ=325µ
II CCT=500µ, -8D
8*15=120µ + 100µ=220µ
500µ-220µ=280µ
SAFE
CHOOSE OTHER
OPTION

22.  Most refractive eye surgeries are done on an outpatient basis.
This means you go home the same day and don’t stay
overnight in a hospital. Most surgeries last less than 1 hour.
Before surgery:
 Arrange for someone to drop you off and pick you up after
surgery.
 Don’t wear your contact lenses for as long as advised. This is
to prevent any effect on the shape of the cornea.
 Don’t wear eye makeup for 2 days before surgery.

23.  Refractive eye surgery involves minimal discomfort. The eye is
usually numbed with eye drops before surgery. You may be awake
during the surgery. Your eye may be kept open with an eye
speculum. This is a spring-like device put between the eyelids.
 After surgery, you may take pain medicine and use eye drops to ease
discomfort. Your eye surgeon will give you more information. The
most common after-effects of surgery include:
 Sensitivity to light
 Blurry vision
 Minor discomfort
 Dry eyes
 Recovery time from surgery varies depending on the surgery. Full
recovery may take days, weeks, or months.

24.  LASIK is the most common type of refractive eye surgery.
Benefits of LASIK include:
 Less pain and faster recovery
 It can correct a wide range of myopia
 It can be repeated to correct vision further
 The eye is not weakened, because only one flap is cut into the
cornea
 Little or no scarring of the cornea
 But other types of surgery may be more suitable for your
needs. And refractive eye surgery is not an option for
everyone. Talk with your healthcare provider about your type
of vision problem, and if surgery may be right for you.

25.  Orthokeratology is a process that uses specially
designed contact lens to temporarily reshape the contour of
the cornea to reduce myopia (nearsightedness).

26. THANK YOU