This document discusses viscoelastic substances used in ophthalmic surgery. It begins with an introduction and history of viscoelastic use, noting sodium hyaluronate was the first substance used in 1972. An ideal viscoelastic is described as being easily inserted and removed while protecting delicate tissues. Viscoelastic properties of viscosity, viscoelasticity, pseudoplasticity and surface tension are explained. Common compositions include sodium hyaluronate, chondroitin sulfate and hydroxypropyl methylcellulose. Viscoelastic are classified as high viscosity cohesives, lower viscosity dispersives, or viscoadaptive. Clinical uses include cataract surgery, glaucoma surgery, and keratoplasty. Complications

1. DR.PRATIK MOHOD

2. INTRODUCTION
Substances having dual properties
1.Viscocity of fluid
2.Elasticity of gel or solid

3. history
 Viscosurgery was a term coined by
Balazs
 Sodium Hyaluronate was 1st used in
ophthalmic surgery as viscoelastic in
1972 as a replacement for vitreous &
aqueous humor

4. Ideal viscoelastic
 Ease of infusion
 Retention under +ve pressure in eye
 Retention during phaco
 Easy removal/no removal needed
 Doesnt interfere with instruments/IOL
placement
 Protects endothelium
 Nontoxic
 Does not obstruct aq.outflow

5. The viscoelastic substances
must be
 Non toxic
 Nonpyrogenic
 Non inflammatory
 Nonimmunogenic
 Sterile for ude in human eye

6. PROPERTIES
viscoelasticity
viscosity
Pseudo plasticity
surface tension
RHEOLOGICAL PROPERTIES

7. VISCOELASTICITY
 Elasticity refers to the ability of a
solution to return to its original shape
after being stressed
 Elasticity allows the anterior chamber to
reform after deformation by depression
on the cornea when external forces are
released.

8. viscosity
 Viscosity reflects a solution's resistance
to flow,
 A function of the molecular weight of the
substance.
 Viscosity of OVDs is measured in
centipoise (cPs) or centistokes (cSt),
which are measures of the resistance to
flow relative to a given shear force.
 The higher the solution's molecular
weight, the more it resists flow

9. pseudoplasticity
 Pseudoplasticity refers to a solution's
ability to transform when under pressure,
from a gel-like substance to a more liquid
substance
 More pseudoplastic a material is, the
more rapidly it changes from being highly
viscous at rest to a thin, watery solution at
high shear rates.

10. Surface tension
- The coating ability of an OVD is
determined not only by the surface
tension of material itself but also by the
surface tension of the contact tissue,
surgical instrument or IOL.
- By measuring the angle formed by a
drop of OVD on a flat surface (contact
angle),the coating ability is estimated.
- At lower surface tension & lower
contact angle, better ability to coat.

11. COMPOSITION

12. Sodium hyaluronate
 Biopolymer, disaccharide
 occurring in many connective tissues
throughout the body, including both the
aqueous and vitreous humors
 Hyaluronate has a half-life of approximately
1 day in aqueous and 3 days in vitreous.
 Mainly present in visco cohesives

13. Chondroitin Sulfate
 Chondroitin sulfate (CDS) is another
viscoelastic biopolymer that is found as
one of the three major
mucopolysaccharides in the cornea.
 Obtained from shark fin cartilage
 Eliminated from the anterior chamber in
approximately 24 to 30 hours
 Coats tissues but poor space maintainer

14. Hydroxypropyl methyl cellulose
 Does not occur naturally in animals but is
distributed widely in plant fibers
 Easy availability
 Ease of preparation
 Storage at room temperature
 Ability to with stand autoclaving
 Main component in dispersives

15.  HYALURONATE PRODUCTS
Healon, Healon5, Healon GV, Healon D
Amvisc, Amvisc plus, Provisc
 HA+CS PRODUCTS
Viscoat, Discovisc
 HPMC PRODUCTS
Occucoat, Cellugel

16. Classification of OVDs
High viscosity-cohesive OVDs
Lower viscosity-dispersive OVDs
Viscoadaptive OVDs
1
2
3

17. Classification
 High Viscosity cohesive
 A)super viscous
cohesive(>1000000mPs)
 B)Viscous Cohesive; OVD(bet
N100000and 10000
 Lower viscosity dispersive
 Viscoadaptive(Healon-5)

18. COHESIVES VS
DISPERSIVESCOHESIVES DISPERSIVES
High viscocity Low viscocity
Low mol wt High mol wt
Long chain molecules Short chain molecules
Adhere to themselves through
intramolecular bonds, resists breaking
apart.
They adhere well to external surfaces,
e.g., tissues and instruments.These
materials tend to break apart easily
High degree of pseudoplasticity and high
surface tension
Lower surface tension and lower
pseudoplasticity

19. COHESIVE
DISPERSIVE

21. HIGH VISCOSITY--COHESIVES
SUPER VISCOUS VISCOUS
1.Healon GV(1.4%)
2.Ivisc plus 1.Ivisc
2.Provisc
3.Healon(1%)
4.Amvisc

22.  All products contain Na.hyaluronate
 Indications of highviscous cohesive
OVD-
-To deepen the AC
-To enlarge small pupils
-to dissect adhesions
-during IOL implantation

23. ADVANTAGES
1.Maintain space at low shear rates
2.Easily displaced at high shear rates
3.Sticks together,aspirated out easily
4.Low risk of post op IOP rise even if
retained
DISADVANTAGES
1.Minimal coating,so less endothelial
protection

24. LOWERVISCOSITY-- DISPERSIVES
MEDIUM VISCOCITY VERY LOW VISCOCIT
1.Viscoat
2.Vitrax
3.Cellugel
4.Biovisc
1.Occucoat
2.Ocuvis
3.I-cell
4.Hymecel
5.Viscilon
Most of them are Hydroxypropyl methyl cellulose

25. ADVANTAGES
1.Excellent coating and gives superior
endothelial protecton
DISADVANTAGES
1. Complete removal of dispersive OVDs is
difficult because the molecules do not
tend to join together and do not aspirate
as a unit,
2. Do not maintain or stabilise spaces
3. Can form microbubbles and obscure view
4. High risk of post op IOP rise

26. viscoadaptives
 Behaviour changes at different flow rates
 Acts as a viscous cohesive agent at lower
flow rate & as a pseudo-dispersive agent
at higher flow rates
 Adapts its behaviour to surgeon’s needs
during surgery
 Highly purified non inflammatory high
mol.wt. Na Hyaluronate at a 2.3% conc.
dissolved in a physiological buffer
 Example  HEALON 5

28. ADVANTAGES
 1. Crystal clear & has higher refractive index than
aq.humor, so increases clarity within surgical field.
 Ability to bind to & to protect delicate corneal endoth.
cells from debris & turbulence during phaco
 Helpful in small pupil as it causes viscomydriasis
 Neutralises the +ve vitreous pressure & prevents the
capsulorrhexis extension
DISADVANTAGES
1.Risk of post op IOP rise if retained

31. Clinical uses
 Cataract surgery
 Protection of endothelium
 Maintaining of AC
 CAPSULAR RHEXXIS
 Cleavage of lens structure
 Visco ecpression of lens
 Phacoemulsification of nucleus
 IOL implantation
 dilate the pupil & maintain a good
intraoperative mydriasis

32. Soft shell technique
 Developed by Arshinoff
 Use of both lower viscosity dispersive &
high viscosity cohesive OVDs together
to minimise their drawbacks & to get
best properties of both

33. Soft shell technique

34. Ultimate soft shell
technique

36. uses
 Floppy iris syndrome,the soft-shell technique
can hold the iris in place throughout the surgery.
 cases of broken zonules, the dispersive OVD
can compartmentalize the eye and keep vitreous
pushed posteriorly, while the cohesive OVD
keeps the anterior chamber formed and
pressurized.
 highly myopic eyes, dispersive OVDs protect
the cornea, while re-application of cohesive
OVDs to pressurize the anterior segment can
minimize traction on the vitreous base and
decrease retinal risk

38. Glaucoma surgery
Visco-canalostomy
 Means opening of schlemm’s canal by OVD
 A Nonpenetrating procedure ,independent of
external filtration
 Advantages-decrease risk of infection,
-decrease incidence of cataract
-hypotony
-flat AC
-Excludes risk of late infection &
conjunctival & episcleral scarring
 Healon GV and healon5 are used

39. keratoplasty
 Used to fill the AC before removing corneal button
from donor eyes as it helps to protect corneal
endothelium and provides an even and circular
trephination
 In recipients eyes helps to have even and circular
trephination,protects other intraocular structures
maintains IOP and prevents sudden collapse of AC
during trephination
 In lamellar keratoplasty helps in the dissection of
deep stroma during dissection of recipients
stroma,called viscodelamination of cornea

40. Posterior segment surgeries

41.  In strabismus sx Force required to bring the
muscle to its insertion is significantly less
with the use of subconjunctival viscoelastic
 In plastic surgery during DCR helps in
identifying lacrimal sac
 Viscoelastics have a role in canalicular
repair where the uninjured canaliculus is
irrigated with fluorescein dye tinted
viscoelastic , that spills from the other end ;
helping to locate the proximal end of the
injured canaliculus
 In AS trauma helps to separate salvageable
tissues from damaged tissues during sx

42. Recent uses
VISCOSTAINING OF CAPSULE
 Techniques-staining from above under an air
bubble & intracameral subcapsular inj.of
Fl.Na ( staining from below)with blue-light
enhancement.
 Any instrument entering eye will cause some
air to escape with rise of lens-iris plane
 A small amount of high density viscoelastic
placed near incision prevents air escape &
minimizes risk of sudden collapse.
 Alternatively-dye mixed with OVD called as
viscostaining of ant.lens capsule covers ant
capsule without coming in contact with

43. VISCO ANASTHESIA
 Mixture of OVD with an anesthetic soln
(known as VISTHESIA) had advantages
of viscosurgery, maintainence of ACD,
capsular bag expansion, protection of
corneal endothelium.
 Prolongs anesthesia
 No extra surgical step for intracameral inj.
Of lidocaine
 Contains topical component -0.3%
hyaluronic acid with 2% lidocaine in a
single dose unit
 Intracameral component-1.5%hyaluronic

44. Removal of ovd’s
-Rock & Roll method
-Two compartment technique
-Bimanual irrigation & aspiration
technique

45. COMPLICATIONS OF OVD
USE
 Post-op. increase in IOP
- Occurs in 1st 6-24 hrs & resolves
spontaneously within 72 hrs
- Due to mechanical resistance at TM
 Crystallization of IOL surfaces
- Due to precipitation or deposition of
viscoelastic soln.
- Fern like or amorphous appearance
- IOL should be explanted & exchanged

46. Capsular block syndrome or Capsular
bag distension syndrome (CBS)
Characterised by accumulation of liquefied
substance within a closed chamber inside
the capsular bag, formed because the lens
nucleus or the PCIOL optic occludes the ant.
capsule opening created by capsulorhexis
 Classified as :
1.Intra-op – time of nucleus luxation
following hydro-dissection
2.Early post-op
3.Late post op. – with liquefied after
cataract

47.  eg.Use of high density viscoelastic agent
like Healon GV causes late CBS
 Reduced distance visual acuity and
improved near acuity due to induced
myopia :forward shift of IOL.
 IOP is normal, despite shallow anterior
chamber.
 Treatment is done by yag laser application
to anterior capsule to allow OVD to
escape anteriorly or posterior capsule
may be lasered with escape of OVD

48. Pre treatment - Accumulation of turbid
fluid in the space between IOL and
posterior capsule
Pre treatment UBM - UBM showing in
the bag IOL and posterior bowing of
posterior capsule
Post treatment UBM - UBM confirming
disappearance of retro IOL space following
YAG laser
Post treatment - Following YAG laser
capsulotomy disappearance of turbid fluid

49.  Calcific band keratopathy
- Occurs with chondroitin sulphate
containing OVDs
 Pseudo Anterior uveitis
- Due to OVDs viscous nature & the
electrostatic charge of it
- RBCs & inflammatory cells remain in AC
giving it appearance of uveitis
- Spontaneously resolves within 3 days
- Intra ocular hemorrhage may be trapped
between vitreous space & OVD in AC
mimicking VH

50. THANK YOU