Suture in ophthalmic surgery

1. Suture material properties
•Tensile strength : it is duration of suture holding strength in the tissue . This can be tested by special devise
called [tensiometer] and this done by holding the suture between 2 jaws (rolled edge) 8 cm apart then pull
the suture at speed 50 cm/min till the suture is broken and this procedure repeated 10 times then the
average is taken ,by this way we can measure the elasticity and irreversible deformity of the suture
•Absorbability : it is duration of suture degradation in the tissue .there are 2 types :
1.Enzymatic degradation :elicit marked inflammatory reaction
2.Hydrolytic degradation : cause less reaction
Both tensile strength and absorbability depend on type of suture material , suture size and tissue
environment into which the suture is placed
•Knot strength :it is the forced required for the knot to slip .
•Configuration :
1.Monofilament
2.Multifilament
•Elasticity : the degree of suture stretches and return to original length .
•Memory or suture stiffness :
high memory :mean suture stiffness ,difficult to handle with ,unties
•Tissue reactivity : peak of inflammatory reaction in the first 2-7 days

2. IDEAL SUTURE PROPERTIES
Handle comfortably
Knot safely without fraying
Minimal tissue reaction
easy to Sterilized
Have no electrolytic ,allergenic ,capillary or carcinogenic action
High tensile strength
Should be absorbed after serving it`s function
Unfortunately there is no single suture has all these properties ,so there is no single suture is
suitable for all purposes .

3. Suture material division
•Suture material can be divide into absorbable or non-absorbable , monofilament or
multifilament , biological or synthetic

Absorbable suture non-absorbable suture
•Can be defined as the suture that loses
most of it`s tensile strength withen 2
month
•It undergoes either enzymatic or
hydrolytic degradation ,the time it take for
suture to be absorbed vary with the type of
material.
•No foreign body lifted in the tissue
•Usually elicit marked inflammatory
reaction
•It`s effective tensile strength remain for
several month or even permanent
•It has reduce or absent degradation .
•Foreign body is lifted in the tissue
•Usually it is inert with minimal tissue
reaction

4. Suture material division
monofilament multifilament
•Has smooth surface that provide easy passage
through the tissue
•Does not support bacterial growth
•Has no capillary action
•It is slipary ,stretchy, difficult to handle with
•It has stiff end that cause irritation if the knot is
not buried
•it has coarse traumatic surface that provide tissue
drag
•The potential spaces between the filament act as
nidus of infection
•Has capillary action that prone for leakage of fluid
from the tissue
•Not elastic easy to handle with and safely tying
•Soft and pliable well tolerated by the patient

5. Absorbable sutures [natural]
•Plain gut :it is natural absorbable suture made from highly purified connective tissue
(mostly collagen) derived from mucosal and submucosal layers of sheep and beef intestine
It has low tensile strength ( < 1 week ) and may absorbed rapidly in the infective tissue or area with high
enzyme level
It undergoes enzymatic degradation and usually elicit marked inflammatory reaction and may even provoke
allergic reaction
•It may be used in wiess`s procedure to evoke inflammation and fibrosis
•Chromic gut : it is similar to plain gut but cover with chromic salt ,the covering chromic salt will
prolong it`s tensile strength ( 2-3 week) ,decrease tissue reaction ,increase resistance to body enzymes .
It is also used in weiss`s procedure .
•Collagen : this derived from flexor tendon of beef ,it is more consistent in strength and smoother
surface and also elicit less reaction than gut suture
it is also available in plain collagen ( < 1 week) and chromic collagen ( 2-3 week) .

6. Absorbable suture (synthetic)
•Polyglactin 910 (vicryl ):
Vicryl made from polyglycolic acid + lactic acid ,it is available in monofilament and braided multifilament
Coated vicryl (or vicryl plus ) is covered with polyglactin 370 +calcium stearate (the coating make the
suture smoother and softer thus decrease tissue drag )
Tensile strength : 2-3 weeks
Complete absorption occur after 2-3 month
Undergoes hydrolytic degradation
It is commonly used in strabismus surgery and conjectival closure
•Polyglycolic acid(dexon):
There are 2 types :
1- dexon s :is braided polyglycolic acid without coating
2- dexon plus :treated with surface lubricant poloxamer 188
Tensile strength : 2-3 weeks
Complete absorption occur after 2-3 month
It is rarely used in anterior segment surgery .

7. Absorbable suture (synthetic)
•Polydiaxanon (pds ):
It is either mono or braided multifilament made from polyester and polydiaxanon
Pds is ideal for internal tissue whenever long lasting absorption is required
It has very stiff end
Tensile strength : 4-6 weeks
Complete absorption occur after 6 month
There is a new study to develop a self knotting suture made from polydiaxanon with bidirection barbs ,
but this not useful for many purposes (the smolest suture available is 6/0 ) , in this study they consider
knotting is time consuming and the knot it self act as potential space for bacterial growth .
•Polytrimethylene carbonate (maxon ):
It is stronger than pds and better knot tying than vicryl .
Tensile strength : 4-6 weeks
All synthetic absorbable suture undergo hydrolytic degradation with mild inflammatory
reaction during absorption process .

8. Non-absorbable suture
•Silk :
Silk is natural multifilament derived from spider coccon , there are 2 types :
1- virgin silk :it is fibrin coated with sericin (with gum) twisted together
2- braided silk : remove all the gum and wax (sericin is removed) then braided together
Tensile strength : 3-6 month
Complete absorption may occur after several years but still considered as non-absorbable suture
It elicit moderate inflammatory reaction
It is not elastic so easy to handle and safely tying ,it is also the most soft and pliable that well tolerated
by the patient .
•Polyamid (nylon)(ethilon) :
It is the commonest suture that used in microsurgery becuose of it`s consistent tensile strength ,smooth
and even surface and it`s good knotting property .
It is relatively elastic with stiff end ,that why the knot must be burried
It is monofilament made from polyamid 6.6 .
It loses 10-15 % of it`s tensile strength every year .
Commonly used to close corneal wound .

9. Non-absorbable suture
•Polypropylene ( prolene ) :
It is the most elastic monofilament with very stiff end that erode through the incision ,so must
burried well
It retain tensile strength over 2 years
Inert and elicit minimal reaction
It has non-hydrolytic ,so not affected by body fluid
Useful for suturing non-healing structure e.g. iris wound , intra-ocular lens to iris fixation .
•Polyester :
It is the strongest and least elastic suture that has perminent tensile strength ,that why it is
commonly used retinal surgery . There are 2 types :
1- braided polyester ( mersilene )
2- coated polyester (ethibond ) coated with small amoant of polybutylate
•Polybutester ( novafil ) :
Slightly elastic ,with high tensile strength that last years .
•Polyvinylidene fluoride ( PVDF ):
it is monofilament similar to prolene but with better and tighter knot .

10. Suture size { gauge }
The size of the suture refer to the diameter the suture strand ,and this can be measured by to ways
1- usp :adapted by united state pharmacopoeia ,in which the diameter denoted as zero ,the more zero the
smaller size suture ( 4/0 larger than 5/0)
2- metric measurement :it is the newest and adapted by European and USP ,in which the suture diameter
measured in mm .(it is more accurate ) .
Metric number USP
0.1
0.2
0.3
0.3
0.4
0.5
0.7
1
1.5
2
3
3.5
11/0
10/0
9/0
8/0 Virgin silk
8/0
7/0
6/0
5/0
4/0
3/0
2/0
0

11. SURGICAL NEEDLES
•Prior to 1959 eyed needles was commonly used in USA ,the problem with eyed needle threaded with
suture that double thickness suture will pulled through the needle tract ,however ,only single thickness
suture is lifted tied in the incision ,this lead to needle tract larger in diameter than the suture ,and this
prone for leaking of fluid and entering of infection .
•At 1914 swaged needle manifuctured (which mean permanent attachment of the suture to the needle
at the time of mannifacture ) . There are 2 basic styles for needle swage :
1- laser drill :forming a hole in the trailing end of the needle into which the suture is fixated .
2- channel fixation :making planed cut that is half the thickness of the needle along the trialing end and the
suture is fixed to a depression in the cut area .
The disadvantage of channel fixation is that the suture can be loosen or the swage deformed if grasped by
needle holder ,so laser drill is preferable .

12. Anatomy of a Surgical Needle

13. Needle Shapes
•Eye
•Microsurgery
•Dura
•Eye
•Fascia
•Nerve
•Muscle
•Eye
•Skin
•Peritoneum
•Cardiovascular
•Oral
•Pelvis
•Urogenital tract
•Nasal cavity
•Nerve
•Skin
•Tendon
•Eye (Anterior
segment)
•Laparoscopy

14. Ideal needle properties
•Sufficiently rigid : to resist bending and ductility but not so rigid that breake easy
if stressed
Ductility mean the amount of deformation that the needle can withstand without
breake
•Long enough :to be grasped by needle holder without blunt the point
•Sufficient diameter and sharp edges :to form large enough tract to allow the
knot to be burry .
•Not traumatic as possible

15. common needle in ophthalmplogy
•Cutting :
Configuration :triangular with 3
rd
edge in the inner (top) surface ,so the cutting will be at the tip and 3
edges
It track`s superfecialy so may pull out the tissue during passage of the needle
Used in tough tissue ,full thickness bite .
Reverse cutting :
Configuration :traingular with 3
rd
edge at the outer (buttom)surface ,so the cutting will be at the tip
and 3 edges .
It track`s deeply ,so accidental perforation may occur with partial thickness suture e.g. rectus –scleral
fixation
It is ideal for oculoplastic surgery as it pass easy through the epidermis
Prime needle :
It is modified cutting or reverse cutting with peveled edge ,this narrow edge make the needle very shap
but affect easy with tissue density (bend easy).

16. Cutting Needles
•Conventional Cutting
•Reverse Cutting
•PRIME
•P Needle

17. needles
Spatula :
Configuration :trapezoid with 4-6 sides ,so the cutting will be at the tip and the sides
This configuration allow the needle to split the tissue lamella and stay in the intralamellar
plane ,so avoid accidental perforation .
Most commonly used in anterior segment Surgery e.g. cataract ,sequint surgery .
Taper point :
It has round body that taper to the point ,so cutting will be at the tip only .
Round body needle designed to separate tissue fiber rather than cutting them
It used in delicate tissue e,g., iris
It produce the smallest hole of all needles ,so used wherever water tight seal is required e.g.
conjectival flap in trabelectomy .
Taper cut :
It has round body with cutting edges at the point only to facilitate penetration

18. Round Bodied Needles
•TAPERPOINT

19. Packaging…
Expiry date
Batch Number
Do Not Re-use
Product (re-order) CodeImperial Gauge
Metric Gauge
Needle size
& curvature
Needle type
Needle point
See Instructions
for use
Needle profile
Sterilised
Ethylene Oxide

20. Use of Needle Holders
Loading
Needle
Needle
passing
through
skin