Wound Construction

Abstract

Surgical limbus can be divided into two zones by three lines (Figure 1) 1 Anterior limbal border: corresponds to termination of Bowman's membrane and is marked externally by insertion of Tenon's capsule and conjunctiva that forms a prominent ridge. Middle limbal border: when conjunctiva and Tenon's capsule is dissected there is a bluish zone visible followed by a white zone of sclera. The junction between these two is known as middle limbal border. This is the termination of Descemet's membrane and overlies the Schwalbe's line. Posterior limbal border: lies over the scleral spur and can be seen only with sclerotic scatter. It is 1 mm behind the middle limbal border. Astigmatic Neutral Funnel The concept has been derived from two important mathematical equations: • Surgically induced astigmatism (SIA) α length of incision 2 • SIA α1/distance of incision from corneal centre Therefore, it was found that incision of 3-3.5 mm at the limbus results in minimal astigmatism of 0.25 – 0.50 D and it can be considered astigmatically neutral for all practical purposes. The funnel's base is at the limbus and as it moves away it widens (Figure2). The incision which is made within this funnel is astigmatically neutral. A self sealing incision is characterized by a corneal valve and square incisions. When IOP of the eye rises it causes corneal valve to close against the pressure of aqueous so that it is pushed up against the dome of cornea. The smoother and larger is corneal lip, better is the sealing action. A 4 mm width with 1.75 mm length is sufficient to create a self sealing incision 3 .

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The trend in the cataract surgery has been towards smaller
incision, moving from superior scleral incision to temporal
clear corneal incision, in an attempt to reduce post operative
astigmatism.
Anatomy of Limbus
Surgical limbus can be divided into two zones by three lines
(Figure 1)1
Anterior limbal border: corresponds to termination of Bowman’s
membrane and is marked externally by insertion of Tenon’s capsule
and conjunctiva that forms a prominent ridge.
Middle limbal border: when conjunctiva and Tenon’s capsule is
dissected there is a bluish zone visible followed by a white zone of
sclera. The junction between these two is known as middle limbal
border. This is the termination of Descemet’s membrane and
overlies the Schwalbe’s line.
Posterior limbal border: lies over the scleral spur and can be seen
only with sclerotic scatter. It is 1 mm behind the middle limbal
border.
Astigmatic Neutral Funnel
The concept has been derived from two important mathematical
equations:
• Surgically induced astigmatism (SIA) α length of incision2
• SIA α1/distance of incision from corneal centre
Therefore, it was found that incision of 3-3.5 mm at the limbus
results in minimal astigmatism of 0.25 – 0.50 D and it can be
considered astigmatically neutral for all practical purposes. The
funnel’s base is at the limbus and as it moves away it widens
(Figure2). The incision which is made within this funnel is
astigmatically neutral.
Self Sealing Incision
A self sealing incision is characterized by a corneal valve and square
incisions. When IOP of the eye rises it causes corneal valve to
close against the pressure of aqueous so that it is pushed up
against the dome of cornea. The smoother and larger is corneal
lip, better is the sealing action. A 4 mm width with 1.75 mm length
is sufficient to create a self sealing incision3.
Classification of Small Incision
Small incision means any incision having a size of 5mm or less.
These can be classified into following categories:
•Site
• Position
•Size
• Shape
Depending on the Site
Incision can be of following types on the basis of the site.
•Temporal
•Superior
• Oblique: superotemporal / inferotemporal
• In correspondence to axis of greater curvature.
The site of incision depends on induced astigmatism and
ergonomics of the surgery.
The temporal approach provides the surgeon easiest access to the
surgical zone because it is not obstructed by the orbital edge of
frontal bone and minimizes the effect of Bell’s phenomenon. The
horizontal meridian of cornea is more than the vertical meridian.
Therefore, the distance from periphery to visual axis is longer in
this position and it is also less flattening. More over there is no
role of bridle suture in such cases. There is also marked increase in
the red reflex because the iris is perpendicular to the light of
microscope. It also facilitates drainage of fluid through lateral
canthus and thus prevents fluid accumulation. Therefore, the most
Wound Construction
Shalini Mohan MS, Sudarshan Khokhar MD, Anand Aggarwal MD, Anita Panda MD, FRCS
Cataract
Dr. Rajendra Prasad Centre for Ophthalmic Sciences,
All India Institute of Medical Sciences,
New Delhi-110029 Figure 2. Astigmatic neutral funnel
Figure 1. Surgical limbus

14 DOS Times - Vol. 13, No.1, July 2007
popular incision these days is temporal approach as it also produces
excellent results in terms of astigmatism, both immediate and
long term3.
The superior approach was popular few years ago but now it is
preferred only in the cases of the sclero corneal tunnel. It can be
used to reduce with the rule astigmatism. It is found that induced
astigmatism from temporal versus superior incisions is 0.6D versus
0.9D3. This is due to effect of flattening which is less in the temporal
approach than the superior.
The oblique incisions are made for better ergonomics but only
provide partial benefit of temporal incisions.
The incisions on the steepest meridian (on-axis) can be made to
reduce mild pre operative astigmatism of 1 D or less as it causes
flattening of the meridian in which incision is given with increase
in curvature of the opposite meridian2. A latest study done by
making ‘on axis’ incision, in various locations to correct
preoperative astigmatism showed that nasal incision increased
preoperative cylinder from 1.13 D to 1.83 D 6 months after
surgery.4
Depending on the Position
Depending on the position incision can be of following types:
• Corneal
• Limbal (near corneal)
•Scleral
• Sclero-corneal
For the obvious reasons the astigmatism decreases as the incision
moves from the clear cornea to the sclera.
Corneal Incisions
The incisions are known as clear corneal when the anterior limit is
positioned anterior to the limbal vascular arches.
Advantages
• The surgery can be performed under topical anaesthesia
• Obviates the need for manipulation of conjunctiva and
therefore reduced scarring which offers futures advantages
of filtering surgery, if required
• Esthetically satisfactory result
• Facilitates intraoperative visibility as the tunnel is shorter and
hence less intra operative stria formation
• Total surgical time is less
• Fewer instruments are required
• There is no bleeding except in cases of vascularised corneas.
Therefore, there is lower incidence of hyphemas and so no
contraindication to anticoagulants
• Decreased incidence of iris prolapse
• The eye is protected from epithelial in growth
• A shallow anterior chamber is extremely rare
• Less chances of formation of peripheral anterior synechia,
because the internal aspect of the wound is further forward
than the cornea /scleral and well away from iris.
• Less chances of expulsive choroidal hemorrhage
• In cases of expulsive choroidal hemorrhage, merely taking
the instruments out results into the immediate closure of the
eye.
• Similarly in the patients with cardiac / respiratory arrest the
instruments can be withdrawn followed by resuscitation.
Disadvantages
There is poor wound stability and therefore it can lead to leakage
causing:
•Hypotony
• Endophthalmitis
• Relatively high astigmatism
• Early high rise of IOP
• Slower healing
Contraindications
• Preoperative radial keratotomy where the incisions extend as
far as limbus (Figure 3)
• Peripheral corneal degenerations
Limbal Incisions
When the external incision is made 0.5 mm posterior to the external
arcades then it is known as limbal incision.
Advantages
Besides the advantages of the clear corneal incisions they have
additional benefits like:
• They induce less astigmatism as they are away from the visual
axis
• Heal more rapidly
Figure 3. Phacoemulcification in operated Radial Keratotomy eye.
Ballooning of conjunctiva is seen.

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• Cause less discomfort
• Offer greater resistance to pressure with respect to clear
corneal incisions.5,6
Disadvantages
• The main disadvantage is ballooning of conjunctiva (Figure 3)
which can lead to poor visibility during surgery.
• The bleeding from the limbal vessels can track into corneal
tunnel and can cause staining of the tunnel which can persist
postoperatively.
• Increased risk of sub conjunctival hemorrhage, which can be
of prime psychological concern for the patient.
Relative Contraindications
The indications of the limbal incision are gradually expanding but
in certain situations corneal incisions are to be preferred over limbal
incisions. These are patients with increased tendency for bleeding3:
• Diabetic patients
• Patients on anticoagulant therapy
• Patients with blood dyscrasias
• Patients with history of alcohol abuse
Sclero Corneal Incision
These incisions are made electively when a larger incision of
5 mm or more is needed to implant an IOL. These are sometimes
also used in pediatric cataract surgery cases for implanting rigid
IOLs. These incisions have got better sealing properties. Thses are
made 1.5-2.0 mm posterior to the limbus (Figure 4). They can be
sutureless if a tunnel is created with an internal corneal lip.
Otherwise the incision can be closed with a single 10-0
monofilament nylon infinity suture.
The scleral flap incision has three dimensions (Figure 5):
• Depth
•Width
• Length
Depth
The sclera is 0.6 mm thick, 2 mm posterior to limbus. So the
incision depth ranges from 0.1 mm to 0.5mm. Flap depth can be
determined accurately with a guarded calibrated diamond knife.
Width
The distance between the external groove and the internal entry
into the anterior chamber is the width of the incision (Figure5).
For production of an astigmatically neutral incision the external
incision should be as far as possible to minimize the effect of the
suture. More over wider the flap, lesser is the astigmatism as it
provides the pillar which supports the existing shape of the eye.
But one can not move too far off as it is limited by the amount of
the bleeding and difficult manipulation in the anterior chamber.
Advantages
• Minimal astigmatism induction
• Better resistance to both internal and external pressure.
Disadvantages
• The conjunctival aperture must be large. Otherwise there is a
need to put in the superior rectus bridle suture or clear corneal
Figure 4. Scleral incision
Figure 5. Scleral flap incision
Figure 6a. Stab (uniplanar) incision

16 DOS Times - Vol. 13, No.1, July 2007
traction suture.
• Diathermy is necessary
• Greater time is required for wound construction
• Greater discomfort for the patient if surgery is being
performed under topical anesthesia. In such cases, a
subconjunctival anesthesia is usually required.
• The manipulation of the instruments inside the eye is difficult
because of frequent corneal distortion.
Depending on the Shape
When examined in longitudinal section, the incisions can be of
following types:
• Single plane, one step stab incision (Figure 6a)- it was
proposed by Fine7 and is prototype of a clear corneal incision.
The blade is driven into the eye upto 2 mm (Figure 6b). Then
the blade is dipped to nick Descemet’s membrane and the
blade is driven upto its hub.
• The Biplanar (Figure 7) was introduced by Williamson2,7 and
is characterized by a groove of 300-400 µm perpendicular to
the corneal surface and is arc shaped. The tunnel starts from
the deepest part of the groove. This shape creates a thicker
corneal flap which is more resistant when caught with forceps
or when sutured.
• Triplanar incision (Figure 8): after making a groove, blade is
made to travel parallel in cornea and then dips down into the
anterior chamber.
• The hinged incision (Figure 9): was proposed by Langerman.8
It is known that when properly performed the corneal
incisions do not leak when ever pressure is applied to the dome
of cornea. But it does leak when the pressure is applied to the
posterior lip of the incision7. This incision is characterized by
a hinge perpendicular to the corneal surface and 0.75 mm
deep. The corneal tunnel is constructed at a depth of about
500 µm, a depth superior than the hinge. This consists of
marking of a groove that is deeper than the plane of the
tunnel. The hinge physically separates the floor of the tunnel
from the posterior wall of the groove. In this way when
pressure is applied onto the posterior lip of the incision, the
groove and the external part of the tunnel open but the internal
part of the tunnel seals. There may be small amount of leakage
in the initial post operative period but this may cause the
inferior part of the corneal lip to become flaccid as it is thinner
than the superior part, therefore it seals the incision.9
Hayashi et al also did a study to correlate between incision sizes
and change in the corneal shape in suture less surgery using corneal
topography. They found that 3.2 mm incision did not induce any
significant corneal shape changes in comparison to 4 mm and 5mm
incisions.10
The shape of the sclero corneal incisions can also be classified in
terms of the initial cut. 7 (Figure 10)
• Parallel to limbus – convex
• Antiparallel- frown incision
• Straight
• Arrow like- chevron incision
Figure 6b. Stab incision being made with MVR knife.
Creation of side port 1.4mm MVR blade.
Figure 7. Biplanar (grooved) incision Figure 8. Triplanar incision

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• “J’ shaped
•Trapezoid shaped
When the incision is made in the astigmatically neutral funnel
then with same chord length and with equal distance from the
limbus, a convex incision will extend slightly outside the funnel
followed by straight and then the concave incision having the least
part outside the funnel (Figure 2) . Therefore, astigmatism will
also be maximum with convex incision. Sagging of the incision
leading to wound gape is also maximum with convex incision.
The last of the above two incisions have been made to reduce
astigmatism as they remain entirely inside the funnel but are not
very popular.
Depending on Size (Length)
The size of the incision can vary from 1 mm to 6.5 mm depending
upon the IOL to be implanted. The insertion with forceps or an
injector tends to widen the incision by 10%7. The recently
developed rollable IOLs can be implanted through an incision size
of 1.1 mm. The studies clearly demonstrate that increase in length
of incision increases the degree of SIA. In cases of sclero corneal
incision, the size of the astigmatically neutral incision can be upto
4.5 mm & in cases operated through corneal or near corneal
incisions the size is 4 mm.
In an experimental study it was found that microincision coaxial
phacoemulsification (2.2mm size) and standard coaxial
phacoemulsification (2.75mm) induce less wound stress and
alteration of wound morphology leading to less wound leakage
than microincision bimanual phacoemulsification (1.2mm)11.
Surgical Technique
Construction of Scleral Tunnel Incision
Wound Architect ure:
The important step in this procedure is creation of a tunnel which
is joined by (Figure 11)
•External incision: it is the scleral groove and the types have
already been described above.
•Internal incision: the entry into the eye
Surgical Steps
• Conjunctival flap is made precisely as the width of the scleral
tunnel followed by vertical releasing incisions in the
conjunctiva and Tenon’s capsule extending approximately 5
mm.
• Mild bipolar cautery is performed. However, the larger vessels
are to be directly and adequately cauterized so that the tunnel
remains dry during the entire procedure.
• Following this a caliper is taken and a 5mm mark is given 1 -
2mm behind the limbus.
• The sclera is cut perpendicularly which should be atleast 50 %
Figure 9. Hinged incision
Figure 10a. Scleral Incisions: parallel Figure 10b. Scleral Incisions: Straight
Figure 10c. Scleral Incisions: Antiparallel Figure 10d. Scleral Incisions: Cheveron

18 DOS Times - Vol. 13, No.1, July 2007
scleral depth (Figure 11) so that the surgeon can look down
the groove and pick the depth within the sclera and dissect
the scleral tunnel.9 A crescent knife is used to dissect the tunnel.
The leading edge of the knife should be down while cutting
anteriorly or sideways (Figure 11).
• Now, viscoelastic is injected into the anterior chamber after
making a side port. This results in a very stiff and stable anterior
chamber.
• A 3.2 mm keratome is brought into the tunnel and at the
anterior edge of the vascular arcade; it is depressed lightly
resulting in a dimple formation on the anterior corneal surface.
The dimple is frequently outlined by a semi circular light
reflex with the tip of keratome at the centre.
• Now, the keratome is advanced horizontally parallel to the
iris which results in a linear horizontal cut through the
Descemet’s membrane into the anterior chamber. A straight
cut in the descemet’s membrane is necessary for the correct
architecture of the incision.
The important thing to note is that forceps is used to elevate the
tunnel roof while placing the keratome inside the tunnel but
counter traction is placed on the posterior lip of the groove rather
than anterior lip during cutting of the Descemet’s membrane with
a keratome. The use of chilled Balanced Salt Solution (BSS)
maximizes cooling of the phaco tip, thus minimizing tunnel
shrinkage and consequent irregular astigmatism.
Internal incision: can be of two varieties –
• Corneal lip incisions – it is created by a 3 step procedure.
Here an external incision is made followed by creation of a
tunnel through the sclera which enters about 2 mm into the
clear cornea. This is followed by entry into the anterior
chamber. This creates the corneal flap/lip which acts as a self
sealing incision. The wound seals when the eye is closed under
normal IOP by injecting saline into the anterior chamber. The
posterior corneal lip is pushed up through pressure of the
fluid into the anterior chamber and closes the wound.
• Non corneal lip incisions – It is directly beveled into the anterior
chamber from external incision in a two step fashion. The
anterior chamber entry is just anterior to the Schwalbe’s
line so that only a small ledge of the descemet’s
membrane is there. It is non self sealing and requires
other associated manuever Suturing lite for sealing to take
place.
Construction of Clear Corneal Incision
A fine Thornton 13 mm fixation ring can be used to allow the
globe stabilization and manipulations without creating conjunctival
tears, sub conjunctival hemorrhage or corneal abrasion. This is
especially true for cases taken up under topical anesthesia. A
sideport is created with a MVR knife. After staining the anterior
capsule with trypan blue, the anterior chamber is pressurized with
a viscoelastic. Now, a 300 µm groove is placed at the anterior edge
of the vascular arcade. Then, an incision is made by depressing the
posterior edge of the groove with a 3.2 mm or 2.75 mm keratome
flattening the blade against the surface of the eye (Figure 12).
Now, the blade is moved in the plane of the cornea until the
shoulders which are 2 mm posterior to the point of the knife
touch the external edge of the incision and following this, a dimpled
down technique as described previously, is utilized to initiate the
cut through the Descemet’s membrane. After phacoemulsification
and cortical clean up, the incision in the Descemet’s membrane is
widened with a blunt tipped keratome depending upon the IOL to
be implanted (Figure 13).
After the anterior chamber is pressurized by BSS through the side
port, the lips of the wound is tested by applying pressure with a
sponge against the posterior lip of the wound. If the incision leaks,
Figure 11. Scleral incision construction
Initial Curvilinear Incision Scleral tunnel central with
crescent blade
Side pocket creation of
scleral tunnel
Figure 12. Clear corneal temporal incision being made

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a single 10-0 nylon monofilament suture is placed. Following
completion of the phacoemulsification procedure, stromal
hydration of the clear corneal incision can be performed in order
to seal the incision.
The rationale for grooved clear corneal incision was to make a
thicker external edge to the roof of the tunnel and less likelihood
of tearing or cheese wiring. Langerman’s single hinged incision
had minimal differences in surgically induced astigmatism from
grooved incision.8
Complications
Intra Operative
Complications can be seen in all types of incisions but clear corneal
incisions by the nature of their architecture and location have some
unique complications associated with them.
Ballooning of conjunctiva (Figure 3): This complication may be
seen if one incidentally incises the conjunctiva. This may hamper
the subsequent visualization due to fluid accumulation and
seriously increases the rate of intraoperative complications
including posterior capsular rent. This can be relieved by making
multiple nicks in conjunctiva to drain the fluid.
Staining of tunnel: Use of crescent blade to make corneal tunnel
can cause blood to track down the incision causing staining of
tunnel (Figure-15).
Premature entry: This common complication especially in
learning curve, can lead to intra operative iris prolapse besides
making the incision non self-sealing and shallowing of anterior
chamber. The options available to deal with this complication are
following:-
• If iris prolapses, it should be reposited back and another tunnel
made underneath the original incision, this time making sure
that the internal entry is more than the original width. The
original incision gets sealed by the roof of the new tunnel
when the pressure is exerted from the fluid entering from the
phaco probe.
• Alternately, the iris is reposited back, the wound secured with
one 10-0 nylon suture, and the surgeon should shift to another
position (if temporal originally, then shifting to a superior
position is appropriate with fresh incision construction).
A calibrated angled diamond knife or a disc knife is also available
for proper tunnel construction. The surgeon should enter the
anterior chamber after injecting sufficient viscoelastic and the blade
should be angled upwards while making the tunnel.
A long entry may result into compromised visualization due to
striae formation in the cornea and make subsequent steps difficult.
Tearing of roof of the tunnel can result especia lly at the edges because
of discrepancy in the size of the incision and phaco handpiece
(Figure 15).
Tearing of the internal lip can also occur causing the incision to
lose its self sealing character or rarely a small Descemet’s membrane
detachment or scrolling of descemet membrane in anterior edge
of the incision.
Incisional burns leading to incision thermal contraction can
develop in clear corneal incisions. They cause compromised self
sealability, corneal edema and severe induced astigmatism. A study
done on 76,581 procedures found incidence of wound burn as
0.98/1000 procedures. Twenty eight percent occurred during early
sculpting, and 71% occurred during fragment removal.12
A extremly narrow tunnel may obstruct the irrigation portion of
the phaco sleeve and compromises inflow which can lead to corneal
burn. This is especially true in cases operated via Micro incision
cataract surgery (MICS). This complication has now been reduced
through various phaco power modulations now available, with
the newer generation phaco machines. Customizable power
Figure 13. Enlargement of incision for implantation of rigid IOL.
5.2mm Keratome for wound enlargement for
PMMA IOL insertion.
Figure 15. Tear of anterior lip due to thin anterior tunnel.
Figure 14. Blood staining of the tunnel.

20 DOS Times - Vol. 13, No.1, July 2007
modulation with microburst and hyperpulse technology13 further
reduces wound temperature during bimanual sleeveless
phacoemulsification. Studies done to compare the thermal effect
of the three recent machines Alcon Legacy AdvanTec, Bausch &
Lomb Millennium, and AMO Sovereign WhiteStar showed that
under a variety of power, load, and duty-cycle settings, the
Millennium and the Sovereign WhiteStar, operating in both pulse
and continuous modes, generated higher peak temperatures than
the Legacy AdvanTec.14
Recently Aqualase emulsification technology is fast gaining
popularity especially in cases of refractive lens exchange. This
technology is supposed to cause minimal heat generation as
microfluid pulses are being employed for nuclear disassembly in
place of ultrasound.
Post Operative Complications
Post operative hypotony may be seen in cases of poor sealability of
incision.
Wound leak and iris prolapse can occur in infrequent case especial ly
if the wound size is more than 3.5 mm width.
Increased risk of endophthalmitis has been noted in a large meta
analysis15 in case operated via clear corneal incision of more than
4 mm size in comparison to sclero corneal incision.
Clinical Course and Outcome
Comparison of temporal clear corneal incision size of 3.5 mm,
4 mm and 5 mm found a mean induced astigmatism of 0.37D,
0.56 D and 0.70 D respectively after 6 months.16
A study done to evaluate the surgically induced astigmatism in the
eyes operated via temporal clear corneal incision versus ‘on axis’
corneal incision showed that the surgical induced astigmatism (SIA)
was less in eyes operated via clear corneal temporal incision.
However, the drawback of the study was a relatively short duration
of follow up before astigmatism analysis (done at 7 weeks).17
A RPC study evaluated paired 3.2 mm
opposite clear corneal incisions made in the
steep axis in one group with single clear
corneal incisions in the other group. Mean
SIA was 1.66 +/- 0.50 D and 0.85 +/- 0.75 D
in Group 1 and Group 2, respectively (P =
.00). They concluded that paired opposite
clear corneal incisions were predictable and
effective in providing an enhanced effect
for correcting preexisting corneal
astigmatism in cataract surgery18.
Table 1 shows various studies comparing
superior with temporal incision. The range
is 0.41D – 0.69 D for temporal clear corneal
in comparison to 0.61D- 0.98D in superior
scleral incision19,20,21,22 .
The effect of 2.75 mm clear corneal incision
on SIA was also reported. The study
revealed that there was little difference in
the SIA of 2.75 mm incision regardless of
the incision site.23
Table 2 20,24,25 shows the range of
astigmatism induced in various studies. Similarly sized incisions
larger than 2.75 mm, when compared in regards to wound location
(temporal versus superior clear corneal incision) have
demonstrated more flattening in the superior axis. The oblique
supero lateral clear corneal incision has also demonstrated more
flattening with the passage of time. That’s why the current trend is
moving towards temporal approach phacoemulsification when
astigmatic neutral incision is desired.
Now it is being emphasized that corneal topography guided
incisions can yield better visual acuity by reducing the pre-existing
astigmatism and inducing less corneal aberrations than
conventional temporal corneal tunnel phacoemulsification.26
A study done to compare the astigmatism and high order
aberrations of the cornea after microincision versus small incision
cataract surgery found that Microincision cataract surgery
generates statistically significantly less corneal astigmatism and
better optical quality of the cornea compared with small incision
cataract surgery. However, microincision cataract surgery showed
no significant advantage in reducing corneal high order
aberrations27. Similarly, corneal and sclero corneal incisions can
also be considered equivalent in terms of inducing higher order
aberrations.
Conclusions
It is a common dictum that ‘well begun is half the work done’. The
incision used for cataract surgery has to serve 3 purposes- the
ease of performance of phacoemulsification, minimum
astigmatism induction, safety and self sealability of the incision.
Smaller size of incision and proper wound construction has
transformed cataract surgery. With clear corneal incisions coming
into vogue, the surgery can be done under topical anesthesia with
relative astigmatic neutrality and almost instant visual
rehabilitation. With increasing expectations of patients following
cataract surgery, it is becoming more and more imperative on part
of the surgeon, not only to give good best corrected visual acuity
Table 1. Studies comparing Astigmatism in scleral tunnel superior and clear corneal
temporal approach phacoemulsification
Author Incision Astigmatism Astigmatism Duration
size (Superior (Temporal of study
approach) approach)
Lyhne 200119 4.0mm 0.61D 0.41D 12 months
Roman et al 199820 4.0mm 0.69D 0.69D 12 months
Oshima et al199721 3.0mm 0.65D 0.56D 3 months
Roman et al199722 4.0mm 0.98D 0.58D 1 months
Table 2. Studies comparing Astigmatism in clear corneal superior and clear corneal
temporal approach phacoemulsification
Author Incision Astigmatism Astigmatism Follow up
size (Superior (Temporal
approach) approach)
Marek et al 200624 2.8mm 0.96D 0.54D 3 months
Roman et al 199820 4.0mm 1.52D 0.69D 12 months
Simsek et al199825 — 1.44D 0.62D 3 months

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but also fairly good uncorrected acuity. For the attainment of the
second goal, proper surgical incisions are now being increasingly
combined either with limbal relaxing incisions or phaco being
performed on the steep meridian to correct pre existing corneal
astigmatism, or through the use of opposite clear corneal incisions
at the time of phacoemulsification.18 No doubt, these incisions
have clearly revolutionized the outcomes and acceptance of cataract
surgery. Taking clues from these incisions, the same incisions are
also being increasingly used for undertaking posterior lamellar
corneal procedures like deep lamellar endothelial keratoplasty
(DLEK).
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Author
Sudarshan Khokhar MD