Demystifying

Tear Substitutes

--Dr. C.A.P Prabhu

Sushrutha Eye Hospital

Mysore

Goal:

• Alleviate symptoms

• Reduce ocular morbidity

• Prevent complications

• Improve the quality of life

• Improve productivity

• Maximize benefits at minimum cost

Management of “Dry” Eyes

• Tear replacement

• Warm compresses

• Education & Lifestyle modification

• Control of inflammation

• Tear conservation

How to keep “Dry” eye ‘not’ “Dry” ?

Can we use:

• Water?

• Saline?

• Tear Substitute?

Tear Substitutes:

Gives relief of symptoms

Improve vision

Helps in restoration of normal ep. of cornea

and conj.

Improves the quality of life

Which Tear Substitute ?

• So many formulations…

• So many companies…

• Are they all same?

• How to choose?

Which drops?

Cause of dry eye

Severity

FormulationsCost and

affordability

Demystify Tear Substitutes

• Components

• When to prefer?

Ideal Tear Substitute

Works like normal tears

Should not alter the

clarity

Lower surface tension of the

tear film

Forms a hydrophilic

layer

Enhances the tear volume

Should not react with the tear proteins

Should not alter the lipid

layer

Ideal tear substitute

pH: 6.5 to 7.5

Refractive Index: 1.336

Surface Tension: 40.1

+/- 1.5 dyne/cm

Osmolarity: 302 +/- 6.3 mosm /

L

Viscosity: 6-12 cps

Anatomy of an artificial tear

Demulcent?

FDA - 6 groups of Ophthalmic Demulcents

• Cellulose derivatives

• Liquid polyols

• Dextran 70

• Gelatin

• Povidone

• Hyaluronic acid

Cellulose Derivatives

• CMC: 0.25 - 2%

• HPMC: 0.2% -0.3%

• Oil in water emulsion

• Also helps Mucin and lipid deficiency

• Can be blended with Glycerine, Carnitine, Erythritol

• Refresh tears: 0.5% lower conc. -less blurring

• Refresh liquigel: 1.00%

• Momentary Blurring

• HPMC is found in Alcon brand lubricants

Cellulose Derivatives

• Celluvisc 1% High viscosity CMC

• Refesh liquigel is a blend of 0.35% high visc. CMC +0.65%medium visc.

• Contrast sensitivity 24 min for celluviscvs 13 min for refresh liquigel

Cellulose derivatives

Viscosity Retention time on eye surface

Celluvisc 350 + + + + + +

Liquigel 70 + + +

Systane 10 + + +

Refresh Tears 1 +

Polyols

Sugar hydrogenated carbohydrates-polyhydric alcohols

Propylene glycol (PG)0.3%

Polyethylene glycol 400 0.4%(PEG 400)

Does not increases the viscosity

Combined with HP guar

Together forms a cross linked Mucomimetic layer

Increase Retention time

Protects corneal surface & promotes repair

Better lubricity > HPMC > CMC

Dextran 70

High mole.wt.polysacharide

Enhances the demulcent nature of HMC

Tears Naturale: 0.3% HPMC +0.1% dextran 70

More viscous & Soothing drop

Increases the retention time

Evaporative dry eyes

Glycerine

Polyols

Glycerine 0.2%

Absorbs water

Polysorbate 80 used oil incorporated emulsions

Refresh endura, Soothe etc.

Inactive ingredient in restasis along with cyclosporine A

Poly Vinyl Alcohol

One of early lubricants . Hydrophilic

polymer

All purpose lubricant

Almost doubles TUBT

0.1% to 4%

Tears plus

Can be combined

with PEG 400 or povidone

(0.6%)

Povidone(Poly Vinyl Pyrollodine)

Iodine -antiseptic

Demulcent property

Increses solubility

Pataday -Olopatadine

2%

Increases the retention

time

Hyaluronic

Normally found in joints, vitreous gel & tears

High water retaining property

Increases bio adhesion

Example: Blink tears, Hyla, Hyvisc, etc.

More useful in Aqueous deficiency

acid

Carbomer 980

Cross linked Poly

Acrylate Polymer

High clarity & viscosity

Short flow properties

High retention time on

eye

• Reliable viscosity agent

• Seldom used

Gelatin

Osmoprotectants

L Carnitine

Erythritol

Taurine

Trehalose, etc.

Bi-carbonate

Normal component of natural tears

It helps in maintaining Mucin layer everywhere

It helps in repairing and maintaining epithelial layer

Potassium

It helps in maintaining Corneal Thickness

Ointments

Mineral oil

White petrolatum

HPMC

Preservative

Night application

Mild- 0.5 % CMC, 0.3% HPMC or Carbomer

Moderate -polyols +/-

gelling agents

Severe - 1% CMC ,

hyaluronic acid, with osmo protectants

Combination of 2 different

tear substitutes

Totally preservative

free

Ointments, gels

Which Tear Substitute?

How Refresh Liquigel is beneficial

Extra Protection

A blend of high and medium – molecular

weight CMC polymers for optimum viscosity 6

With added electrolytes 6

6. Simmons et.al, Refresh Liquigel A New Approach to the treatment of persistent dry eye, Ophthalmic Pract, 2002;20(2):77-80

How Refresh Liquigel is beneficial

Extra Action

Superior mucoadhesivity due

to its polyanioniccharge 6

Mimics the natural mucins of ocular

surface 66. Simmons et.al, Refresh Liquigel A New Approach to the treatment of persistent dry eye, Ophthalmic Pract,

2002;20(2):77-80

How Refresh Liquigel is beneficial

Extra Relief

Brings about significant reduction in signs and symptoms of dry eye 7

Provides continued improvement over time 6

Brings about Goblet Cell Regeneration

6. Simmons et.al, Refresh Liquigel A New Approach to the treatment of persistent dry eye, Ophthalmic Pract, 2002;20(2):77-80,7. Simmons et. al, Clinical performance of a mid-viscosity artificial tear for dry eye treatment,

Cornea. 2007 Apr;26(3):294-302.

Thank you