Refractive surgery and corneal implants

1. REFRACTIVE SURGERIES
Dr.Jyoti Shetty
Medical Director,
Bangalore West Lions
Superspeciality Eye Hospital

2. CLASSIFICATION
REFRACTIVE SURGERIES
CORNEA BASED LENTICULAR BASED COMBINED(BIOPTICS)
-R.K.
-PRK
-LASIK
-EPILASIK
-LASEK
-Conductive
Keratoplasty
-Corneal
Inlays and
rings
-Clear Lens
extraction for
myopia
-Phakic IOL
- Prelex Clear
Lens Extraction
with use of
Multifocal IOL’s
Combination
of the two

3. LASIK(Laser Assisted In Situ
Keratomileusis)
 Procedure using laser to ablate the
tissue from the corneal stroma to
change the refractive power of the
cornea

4.  Types of lasers used-
 Excimer-Excited dimer of two atoms
-an inert gas(Argon)
-Halide(Fluoride)
which releases ultraviolet energy at193nm
for corneal ablation

5.  Non-Excimer solid state lasers-
 210nm Q switched diode pumped laser (laser
off)
 213 nm Q switched diode pumped
laser(Pulsar)

6.  Advantage of Non-Excimer solid state
lasers-
 No toxic excimer gases
 Wavelength closer to absorption peak of corneal
collagen—less thermal and collateral damage
 Better pulse to pulse stability
 Not absorbed by air,water,tear fluid-so less
sensitive to humidity or room temperature
 No purging with inert gases required.

7. Patient selection
 Patients need to be fully informed about
potential risks,benefits and realistic
expectations
 Age should be above 18 years
 Refractive status should have been stable
for at least 1 year.
 Current FDA approval-
 Myopia-upto -12D
 Hyperopia –upto +6D
 Astigmatism-upto 7D

8.  CCT such that minimum safe bed
thickness left(250-270µ).Post op
Corneal thickness should not be
<410µ.
 Cornea not too flat or steep.<36D
or>49D(Poor Optics).

9. CONTRAINDICATIONS
 Systemic factors-
 Poorly controlled IDDM
 Pregnancy/lactation
 Autoimmune / connective tissue disorders(RA,SLE,PAN
etc)
 Clinically significant Atopy,Immunosuppressed patients
 Keloid tendency(esp PPK)
 Slow wound healing-Marfans,Ehler-Danlos
 Systemic Infection-(HIV,TB)
 Drugs-Azathioprene,Steroids(Slow wound healing)

10. CONTRAINDICATIONS
 Ocular Factors-
 Glaucoma,RP(Suction Pressure-ON
damage,Blebs)
 Previous h/o RD or f/h of RD.
 One eyed individual
 Pre-existing dry eye,Keratoconus.pellucid
marginal degeneration,Superficial corneal
dystrophy,RCE,Uveitis,early Lenticular changes
 h/o Herpetic Keratitis(one year prior to surgery)

11. PREOPERATIVE EVALUATION
PRIOR TO LASIK
 Record UCVA and BCVA Snellens V/a
 Dry and wet manifest refraction(with
1% cyclopentolate)
 Pupillometry-Infrared Pupillometer
-Aberrometer
 Large pupil-Increased HOA
perceived so increased glare
-Can change Optic Zone

12.  Slit Lamp Examination-
 Rule out blepharitis, miebomianitis,
pingecula, Pterygium,corneal
neovascularization
 Other contraindications for LASIK.
 IOP by applanation
 Dilated Fundus Examination to role out
holes ,tears.

13.  Tear film asessment-Schirmers,TBUT and
Lissamine staining
 Blink Rate-(Normal---3-7/min)
 Corneal Topography-
 Scanning slit/placido disc
 Stop RGP lenses 2 weeks prior and soft lenses I
wk prior
 To rule out early Keratoconus and other ectasias
 For mean K values

14.  Pachymetry -For CCT
(Ultrasound/Optical)
 Contrast Sensitivity testing for pre-
operative baseline.

15. BASIC STEPS AND
MACHINE SPECIFICATIONS
 Topical anasthesia-Proparacaine
0.5%, Lignocaine 4%.
 Surgical Painting and draping(Lint
Free).
 Lid speculum with aspiration.
 Corneal marking-Orientation of free
cap

16. Creation of flap-
 1st Step-Creation of suction by suction
pump to raise the IOP to 65 mm Hg
which is necessary for the
microkeratome to create a pass and
resect the corneal flap.
 This is crosschecked with Barraquers
tonometer.

17.  2nd step-Resection of corneal flap
Microkeratome Femtosecond Laser
(Intralase)

18.  Microkeratome-
 Uses Disposable blades
 Blade Plate can be set at
120µ,140µ,160µ and180µ.
 Nasal or superiorly hinge flaps can be
created.
 Eg.Hansatome,ACS,Carriazo Barraquer,
Moria.

19.  Femtosecond Laser for Flap-
 Creates photodisruption using femtosecond
solid state laser with wavelength of 1053nm.
 Needs lower vacum.
 Very short pulse with spot size of 3µ-High
precision cutting device.
 Any hinge can be made
 Can make flaps as thin as 100µ(Sub Bowmanns
Keratomileusis)

20.  Flap has vertical edges –so reduced
epithelial ingrowth.
 Microkeratome flap thicker in periphery
and thinner in the centre.Not so with
Intralase(Planar).

21.  3rd Step-Delivery of Laser-
 After flap is lifted, laser is applied to the
stroma according to the ablation profile
calculated by the machine.
 Laser beam is delivered by the following
ways depending on the machine-
Beam Delivery
Broad Beam Scanning Slit Beam Flying Spot

22.  Most machines employ a flying spot to
deliver laser with the help of
incorporated eye tracker.

23.  4th step-Reposition Of the Flap-
 After irrigating interface ,flap reposited
 Adhesion test-Striae test

24. ABLATION PROFILES
 Wavefront Guided or customized
ablation-to improve quality of vision by
correcting higher order aberrations.
-Wavefront analysis on entire eye
done by –Hartmann Shack
-Tracy

25. ABLATION PROFILES
 Aspheric Ablation-Normal LASIK converts
prolate cornea to oblate structure.(Central
flattening,steep in periphery.) which induces
higher order aberrations.
 To reduce this and preserve the prolate
structure,’Q’ value is calculated and altered
to give a more aspheric ablation.

26. COMPLICATIONS OF LASIK
 Under/over correction and regression (over
time).
 Post –op Keratectasia
 Presents 1-12 months
 Progressive regression
 Treatment-RGP,Corneal transplant.
 Prevention- Leave residual stromal bed
-Do surface ablation
-Don’t violatecorneal topography
diagnosis of forme-fruste keratoconus

27. COMPLICATIONS OF LASIK
 Night vision disturbances-Haloes/Glare
 Decenteration and central islands.
 Post Lasik Dry eye-
 Fluctuating vision,SPK
 Temporary neuropathic cornea
 Confocal microscopy-90% reduction in corneal
nerve fibres-regeneration by 1 year.
 Rx-Preservative Free lubricants

28. COMPLICATIONS OF LASIK
 Post op Glaucoma(Pseudo DLK)-
Steroid induced.
 Vitreoretinal Complications-
 Increased risk of RD due to alteration of
anterior vitreous by suction ring-Risk
0.08%.
 PVD(0.1% Risk)
 Macular Hemorrage(0.1% Risk)

29. COMPLICATIONS OF LASIK
 Flap
Complications-
 Button Hole-If
K>50D,due to
central corneal
buckling.
 .

30.  Irregular thin flap-
Inadequate
suction/old blade
 Short Flap-Hinge
encroaches on
visual axis-Due to
jamming of
microkeratome with
hair/FB
SHORT FLAP

31.  Free Cap-Due to
flat pre –op
K(<38D).

32.  .Flap undulations-
 Macrostriae-Linear lines in
clusters,seen on
retroillumination.
Causes-Incorrect
position of flap
-Movement of
flap after LASIK
Rx-Lift flap
-Rehydrate and float it back
-Check for flap adhesion
MACROSTRIAE

33.  Microstriae-Flap in
position but fine
wrinkles seen
superficially
-Due to large
myopic ablation
-Rx-
Observe.They
resolve
spontaneously
MICROSTRIAE

34.  Bleeding during flap cutting due to
corneal neovascularization in contact
lens users

35.  Interface Inflammation(Sands Of
sahara/DLK)-Non-Infective
inflammation at the interface seen in
1st week after LASIK.
 Diffuse,confluent,white granular material
at the interface 1-7 days after LASIK.
 Slight CCC
 No AC reaction
 Reduced Visual acuity

36.  Grade 1-
Focal involvement -
Normal V/A.
Rx Intensive
topical steroids.

37.  II – Diffuse
involvement –
Normal V/A.
Rx-Add
systemic steroids.

38.  III – Diffuse confluent
granular deposits-
Reduced V/A.No AC
reaction.
Rx-Same as
above+Antibiotics
 IV - Diffuse confluent
granular deposits
+intense central striae.
Marked Reduced
V/A
Rx-Interface
irrigation + above

39.  Causes-Proposed Theory
 Bacterial cell wall endotoxin
 Cleaning solution toxicity
 Talc from gloves
 Miebomian secretions

40.  Infection-Potential complication as any
surgical procedure

41.  Epithelial ingrowth-Presents 1-3
months after LASIK.
 Causes-Epithelial cells trapped under flap
 Risk factors-Peripheral epithelial defects
-Poor flap adhesion
-Buttonholed flaps
-Repeat LASIK

42.  Classification-
 GRADE 1-Faint white line <2mm from flap
edge
 GRADE 2-Opaque cells <2mm from flap
edge with rolled flap edge
 GRADE 3-Grey to white fine opaque line
extending >2mm from flap edge.
 GRADE 4-If ingrowth >2mm from edge with
documented progression—Lift flap and
remove the sheets of epithelium.Can use
MMC.

43. EPILASIK / LASEK
 Anterior stroma of cornea (ant. 1/3 rd)
has stronger interlamellar connections
than post. 2/3rd.
So surface ablation preserves the
structural integrity better than LASIK
especially in the correction of
moderate to high myopia.

44.  LASEK-Camellins Technique-
 20% absolute alcohol used for 20-35s. To
raise epithelial flap.
 Flap reposited after ablation

45.  EPILASIK- Epithelial keratome used to
lift epithelial flap of about 60-80µ thick.
 Epithelial keratomes use
- PMMA blades
-Metal Epithelial Separator

46. CONDUCTIVE
KERATOPLASTY
 Uses mild heat from radiofreqoency waves
to shrink collagen in the periphery of the
cornea---This steepens the paracentral
cornea.
 Used for hyperopia (1 – 2.25D) and
presbyopia.
 C.K. spots are applied with a probe in rings
with a dia. Of 6/7/8 mm.
 8 spots are given in each diameter ring.

47. 5mm
6 7

48.  Drawbacks-
 Regression and retreatment in 100%
cases after 6 months.
 Induced cylinder >1D reported in many
cases.
 Usually done in one eye—Many have
intolerance to monovision.

49. CORNEAL INLAYS
 Increase the depth of focus by using pinhole
optics.
 Inlays have 1.6mm centre with 3.6mm
surround.
 Near vision improves by 1.5D with no loss of
distant vision.
 Used in the non –dominant eye.
 These are hydrogel based.Placed in a
tunnel 200-400 µ deep in centre of cornea.

50. AcuSof Corneal inlay

51. Phakic IOLs
 An intra-ocular lens is placed inside the
eye in front of the patient’s natural lens.
 These are available in three types
1. Anterior chamber angle fixated IOL – Nuvita
(Bausch & Lomb), Kelman duet, I care
(corneal), Vivarte (Ciba vision)
2. Iris supported phakic IOL – Verisyse/ Artisan
(AMO/Ophtec)
3. Plate lens that fits between the iris & the
crystalline lens – Starr implantable contact lens
(ICL), PRL (Ciba).

52. Indications
 Age above 18 years
 Stable refraction for one year
 Patients not suitable for LASIK/LASEK
due to high powers or thin corneas
 AC depth 3.0 mm
 Endothelial count >2000cells/cumm
 No other ocular pathology

53. Contraindications
 Myopia other than axial myopia
 Corneal dystrophy/ Endothelial cell count
<2000cells/cumm
 Anterior chamber depth less than 3.0mm
 History of uveitis
 Presence of anterior/posterior synechiae
 Glaucoma or IOP higher than 20 mmHg
 Evidence of nuclear sclerosis or developing
cataract
 Personal or family history of retinal detachment
 Diabetes mellitus

54. Angle supported anterior chamber phakic IOLs – Rigid lenses
IOL NuVita MA20 ZSAL-4 Phakic6
Company Bausch & Lomb Morcher M & C
Prev. model ZB5M / ZB5MF
(Baikoff)
ZSAL 1-3 ________
Material PMMA PMMA PMMA
Optic 5.0 mm 5.8 mm 6.0 mm
Eff.opt.zone 4.5 mm 5.3 mm ??
Haptic + optic 12 -13.5mm 12.0/13.5mm 12 – 14mm
Diopters (D) - 3.0 to – 23.0 D -20.0 to +10.0D
Plano concave (-20
to -3.0)
Convexo-concave
(-2.5 to +4.5)
Biconvex (+5 to
+10)
- 2.0 to -25.0D
+2.0 to +10.0D

55. Angle supported anterior chamber phakic IOLs – Foldable
IOls
IOL Vivarte I CARE Kelman Duet The Vision
Membrane
Company Ciba vision Corneal
(france)
Vision
membrane
technologies
Material Hydrophillic
acrylic (RI =
1.47)
HEMA 26% Optic- Silicone
Haptic PMMA
Silicone
Optic 5.5 mm 5.75 mm 5.5 mm 7.0 mm
Haptic +
optic
12-13 mm 12-13.5 mm 12-13.5 mm
Diopters (D) -7.0 to -25.0 D -20.0 to +10.0D
injectable lens
-8.0 to -20.0 D

56. Anterior Chamber Phakic IOL

57. Kelman Duet phakic IOL
 Two piece phakic IOL. The PMMA
haptic is first snaked through a 1.5mm
incision. The silicone optic is then
compressed & inserted. Once the optic
unfolds in the anterior chamber the two
tabs on either side of the optic are
snapped into projections on the haptic.
The main advantage of this lens is that
the optic can be exchanged with a new
one if the patient’s refraction changes.

58. Iris fixated phakic IOL – Verisyse
Phakic IOL
 Most commonly used phakic IOL
 One-piece design

59. Verisyse Phakic IOL

60. Pre-op assesment for phakic IOL
 Refraction – Objective & subjective
acceptance at 12mm vertex distance
 Anterior chamber depth – from epiuthelium
to endothelium
 Anterior & posterior segment examinations
 K-reading & Topography – Orbscan-II
 Intra-ocular pressure
 White to white measurement
 Specular microscopy

61. Veriflex (artiflex)
 Foldable iris claw lens. It is a
modification of Verisyse (Artisan)
phakic IOl.

62. Posterior chamber lenses
 These phakic IOLs are placed in the
posterior chamber between the iris &
the crystalline lens. These are
1. Starr ICL
2. Cibavision PRL

63. STAAR ICL
 The STAAR Collamer ICL and the TORIC
ICL are posterior chamber phakic intraocular
lenses. Made of Collamer, STARR’s
proprietary collagen copolymer
(colagen/HEMA), the lens rests behind the
iris in the ciliary sulcus.

65. Procedure
 The lens is gently folded and injected
into the anterior chamber through a 3.0
mm, temporal, clear corneal incision.
The ICL is then carefully positioned by
manipulating the footplates of the lens
posterior to the iris plane and and into
the sulcus. Pre-operative YAG
iridotomy is essential.

66. Complications
 ICL decentration
 Pupillary block
 Pigment dispersion
 Subcapsular cataract

67. Advantages of phakic IOLs over
laser corrective procedures
 A higher range of refractive errors can be corrected
 Reversible: Phakic IOL implantation is a potentially
reversible procedure
 Safe: No structural changes are induced. Hence it is
safe in any eye with high error & also thin corneas.
 Better quality of vision: Quality of vision (contrast
sensitivity) is better than the laser refractive
procedures in eyes with higher refractive errors and
no induced higher order aberrations. There is also a
considerable improvement in BVCA with these
lenses because of the magnification effect.
 Highly skilled procedure: Prevents misuse of the
procedure.

68. Bioptics
 Bioptics is a combination of phakic IOL and
LASIK. Bioptics is done for the correction of
the residual spherocylindrical power when a
spherical implant is used.