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Iridectomy
17
Erik Chankiewitz and Frank Wilhelm
Contents
17.1 Introduction..................................................... 183
References and Further Reading .......................................... 186
17.1 Introduction
Iridectomy refers to the excision of a piece of
the iris. Depending on the technical approach, a
corresponding coloboma results (Fig. 17.1).
Performing an iridectomy is one of the fundamental skills of any surgically active ophthalmologist and is therefore typically part of the
training to become a specialist in ophthalmology as the “smallest intraocular procedure.” The
oldest surgical procedure in glaucoma treatment
was introduced as early as the 19th century by
Albrecht von Graefe and is now predominantly
performed with the Neodymium: YAG laser as
laser iridotomy [1]. It is the method of choice
for angle-closure glaucoma as a prophylaxis
for pupillary block. However, for this, the cornea must be sufficiently transparent to allow
E. Chankiewitz ()
Augenklinik, Städtisches Klinikum Braunschweig
gGmbH, Braunschweig, Germany
e-mail: erik@chankiewitz.de
F. Wilhelm
Universitätsklinikum Halle Saale, Greifswald,
Germany
the transmission of laser energy to the iris.
Additionally, any pre-existing anterior synechiae
can be resolved during a surgical iridectomy [3].
It has been shown that, at least after three years,
there is no significant difference between the
two procedures [2].
Today, this procedure is an important step in
many complex operations to achieve the desired
functionality, such as in trabeculectomy, or
essential to prevent postoperative complications,
among others in Descemet endothelial membrane keratoplasty (DMEK) and penetrating
keratoplasty, as Ando-iridectomy in silicone oil
fillings after PpV, as well as in the implantation
of iris-clip lenses or add-on lenses, and many
more.
In this article for beginners in eye surgery,
only the surgical iridectomy to prevent a pupillary block is discussed. The goal is to create a
sufficiently large opening in the peripheral iris
between the posterior and anterior chambers so
that the aqueous humor can flow from the posterior chamber to the anterior chamber bypassing the pupil. This is usually done in the upper
half of the iris. This can prevent later glare, as
the upper eyelid covers the iris defect.
© The Author(s), under exclusive license to Springer-Verlag GmbH, DE, part of Springer Nature 2025
F. Wilhelm (ed.), Ophthalmic Surgery for Beginners, https://doi.org/10.1007/978-3-662-70287-1_17
183
184 E. Chankiewitz and F. Wilhelm
ab
cd
Fig. 17.1 a–d Representation of the basic types of surgically achieved colobomas after basal (a), more peripheral
(b), sector-shaped (c), central (d) iridectomy. [According to 4]
Before starting the iridectomy, the eye must
be carefully examined to determine the ideal
position.
the cornea, some aqueous humor spontaneously egresses, and the anterior chamber slightly
flattens. Now, using an iris forceps or a fine
tying forceps, the iris tissue near the iris root
Areas with strong peripheral corneal vascu-
larization, prominent iris vessels, iris stroma
with little structure (unlike laser iridectomy),
or in the area of iris nevi are particularly
unsuitable.
Before the procedure, the pupil should be
constricted with a series of pilocarpine eye
drops.
is securely grasped. It is gently pulled outward
above the corneal level and the prolapsed iris tissue is cut off flat with a single snip of scissors.
A slight distortion of the pupil towards the paracentesis is usually observed.
It is important to grasp enough tissue so that
the anterior and posterior layers of the iris are
securely cut through, but not so much that a
large opening results, which could later cause
A limbus-parallel corneal incision approximately 1.5 to 2 mm long is made as vertically as
possible through the cornea and close to the limbus (Fig. 17.2). This incision should not be conical (outer and inner openings are the same size)
and not tunneled (Chap. 13). After perforating
glare. Moderate bleeding and pigment dis-
persion into the anterior chamber can occur
and are immediately rinsed out with BSS.
Usually, parts of the iris tissue trapped in
the incision fall back into the anterior cham-
ber. Finally, the incision is sealed by slight
17 Iridectomy
185
Fig. 17.2 Schematic representation of the procedure of a basal iridectomy
hydrating of the stroma using an intrastromal
injection of BSS, and any potential bleeding
is stopped by slightly increasing the intraocular pressure.
Due to the irritation of the iris tissue during the
procedure, it can sometimes lead to a severe
inflammatory reaction, especially in younger
people, which is why postoperative steroid eye
drops are essential. These also prevent the par-
In retro-illumination, the iridectomy appears
red, indicating a full-thickness opening of the
iris.
tially pronounced synechiae with the anterior
lens surface after laser or surgical iridectomies.
To prevent a consecutive increase in intraocular
pressure due to increased pigment dispersion
If the iridectomy is too large, it can lead to
increased sensitivity to glare postoperatively.
Reaching the dilator muscle of the pupil through
the excision results in pupil motility disorders.
and the resulting accumulation in the chamber
angle, postoperative controls for biomicroscopy
of the anterior eye segments with tension con-
trols are necessary.
186 E. Chankiewitz and F. Wilhelm
References and Further Reading
1. Congdon NG, Friedman DS (2003) Angle-closure
glaucoma: impact, etiology, diagnosis, and treatment.
Curr Opin Ophthalmol 14:70–73
2. Fleck BW, Wright E, Fairley EA (1997) A ran-
domised prospective comparison of operative
peripheral iridectomy and Nd: YAG laser iridotomy
treatment of acute angle closure glaucoma: 3 year
visual acuity and intraocular pressure control outcome. Br J Ophthalmol 81:884–888
3. Funk J (2009) Antiglaukomatöse Laserchirurgie Was
war? Was ist? Was wird? Ophthalmo Chir 21:25–32
4. Mackensen G (1989) Chirurgie der Iris und des
Ziliarkörpers. In: Mackensen G, Neubauer H (Hrsg)
Augenärztliche Operationen, Teil 1. Springer, Berlin,
pp 603–649
Intravitreal Injections
18
Klaus Mayer, Christoph Schmidt and Uwe Wilhelm
Contents
18.1 Material and Instrument List........................................ 187
18.2 Patient Selection for Beginners...................................... 188
18.3 Verification of Indication and Identity ................................ 188
18.4 Preparation of the Eye............................................. 188
18.5 Use of an Operating Microscope .................................... 189
18.6 Choice of the Appropriate Injection site............................... 189
18.7 Administration of the Injection...................................... 190
18.8 Aftercare ....................................................... 191
References and Further Reading .......................................... 191
An intravitreal injection at the slit lamp is not
permissible and should be performed in a certified operating room!
18.1 Material and Instrument List
The following instruments and materials should be
prepared before the procedure. The list is a recommendation intended to standardize the procedure
and minimze the risk of infection (Chap. 5):
K. Mayer ()
Augenpraxisklinik im Alleecenter, Remscheid,
Germany
e-mail: kla.mayer@t-online.de
C. Schmidt
Augenärztliche Gemeinschaftspraxis „Augen im
Zentrum“, Greifswald, Germany
U. Wilhelm
MVZ Roswitha und Daniel Krause, Dortmund, Germany
© The Author(s), under exclusive license to Springer-Verlag GmbH, DE, part of Springer Nature 2025
F. Wilhelm (ed.), Ophthalmic Surgery for Beginners, https://doi.org/10.1007/978-3-662-70287-1_18
• PVP-iodine solution 5% and 10%
• Eye drops for topical anesthesia, e.g.,
Conjuncain® (Oxybuprocaine 0.4%, Mann,
Berlin, Germany)
• Eyelid speculum
• Surgical eye forceps or colibri forceps
• Sterile microscope buttons/microscope handles
• Sterile eye dressing, (if necessary, hourglas
dressing)/capsule dressing
• Adhesive strips
• Table cover
• Surgical gloves for assistant
• Surgical gloves for surgeon
• Surgical gown for assistant
• Surgical gown for surgeon
• Two cigarette swabs
• An eye marker (compass 3.5/4.0 mm) or
equivalent
• An eye drape (with incision film)
• Paracentesis knife (in reserve)
187
188 K. Mayer et al.
Eyelid speculum, compass, and forceps can
be used as reusable or disposable instruments.
Disposable instruments can also be obtained as
a complete package along with the additionally
required disposable materials from various suppliers of surgical materials.
18.2 Patient Selection for Beginners
For beginners, it is advisable to start with pseudophakic eyes. Steroid implants (Ozurdex®,
Allergan, Dublin, Ireland, and Iluvien
®
, Alimera
Sciences, Alpharetta, USA) should be avoided at
the beginning due to the larger cannula diameter
and the slightly higher risk of complications.
The first injections should be performed
under the supervision of an experienced surgeon.
18.3 Verication of Indication
and Identity
Before each procedure, the surgeon must verify
the patient’s identity and ensure the correct side
of the operation. Furthermore, they must confirm the correct indication.
For the first indication, a fluorescein angi-
ography is required. Indications during the
course can also be determined via OCT.
Since many procedures are performed consecutively in many surgical centers, a routine must
also ensure that there are no mix-ups with the
medications. Direct personal communication
with the patient provides the final assurance.
The surgeon must ensure that the cold chain
has been maintained when providing the medications. This is relevant for anti-VEGF medications. Iluvien and Ozurdex do not need to be
stored refrigerated.
Fig. 18.1 Irrigation of the conjunctiva with PVP-iodine.
(© Bayer AG)
Stulln, Germany). Furthermore, the eye receives a
topical anesthesia with, for example, Conjuncain®.
To achieve good anesthesia, at least three series
should be administered at intervals of five minutes.
Once good topical anesthesia is achieved,
local PVP-iodine 5% irrigation can be performed (Fig. 18.1). This is mandatory before
every intravitreal injections. A contact time of
at least three minutes is common. The irrigation
is often perceived as unpleasant by the patient,
which is why the topical anesthesia must be performed beforehand. Conjunctival disinfection
with PVP-iodine is considered the gold standard. However, if there is a PVP-iodine intolerance, polihexanide 0.04% can also be used after
informing the patient [6]. The extended contact
time of 20 minutes and multiple applications
must be considered during preparation! The disinfection of the periocular skin and eyelashes is
performed with PVP-iodine 10%. The wiping
of the eyelashes, eyelid margins, and periorbital skin is done twice with a sterile forceps and
a sterile swab. It is important to ensure that no
massage of the Meibomian glands occurs! If
there is an intolerance to PVP-iodine, Octenisept
can alternatively be used for the skin. However,
when using colorless Octenisept, it is not apparent to the surgeon how well the surface disinfection was performed.
18.4 Preparation of the Eye
Before the procedure, a medicinal mydriasis
is performed with, for example, Mydriaticum
®
UD AT (Tropicamide, Pharma Stulln,
Stulln
18.4.1 Preparation of the Syringe
It is best to use a pre-filled syringe. Pre-filled
syringes reduce the risk of contamination and
also facilitate the surgical process with a higher
18918 Intravitreal Injections
number of patients. If the medication still needs
to be drawn up, a filter needle is used for this
purpose. Ideally, a 30G-x-½-inch needle is used
as the injection needle. This is sufficiently thin
to allow for a leakage-free wound closure and
with a low risk of scleral perforation. A LuerLock connection is important for a secure connection between the needle and the syringe. An
injection volume of 0,05 or 0,1 . ml is common.
To remove excess medication and bubbles, you
can tap the upright syringe slightly and then
push the plunger up to the 0,05 or 0,1 ml mark.
18.4.2 Draping the Eye
In the operating room, a renewed check of the
patient’s name and side must be performed
before the injection.
The procedure is performed after surgical
hand disinfection and with sterile gloves.
The eye is now draped with a sterile drape. If
fenestrated drapes are used, an additional incision film is necessary. Generally, specially prepared fenestrated drapes with adhesive film and
perforation line are used so that the eyelids and
eyelashes can be well covered. Before applying
the film, excess disinfectant is removed with a
sterile swab to ensure better adhesion. For better positioning of the film, the lower eyelid is
slightly moved downward with a cigar swab
until a slight ectropion position is achieved. The
patient looks up while the film is applied. The
film is lightly pressed, and the drape is unfolded.
The drape should be positioned towards the
anesthesia bar so that there is sufficient distance
between the mouth and the drape.
An eyelid speculum is used to keep the eye
securely open. Good spreading is important for
free access to the injection without the risk of
touching the eyelid margin and cilia with the
sterile needle tip during the procedure. Eyelid
speculums with closed metal wings can be used
to hold back the cilia.
18.5 Use of an Operating Microscope
The intravitreal injection is a microsurgi-
cal procedure, so it is recommended that
this surgery be performed under a surgical
microscope.
If a supine position of the patient is not possible,
an intravitreal injection can also be performed
without a microscope in individual cases.
The microscope lighting should be set low
so that the patient is not too dazzled and the
eye can be kept still better. Ideally, the patient is
asked to fixate on the microscope light to keep
the eye straight and still.
Depending on where the injection is to be
made, the patient can also be given a different
direction to look.
18.6 Choice of the Appropriate
Injection site
The injection is performed in the area of the pars
plana and is located between 3.5 to 4 mm behind
the limbus [4]. When choosing the location, various factors must be considered. Ideally, a site that
is freely accessible in the straight-ahead view and
thus provides enough distance from the lid margin and eyelashes is chosen. A temporal injection
site has the advantage that the pars plana is widest there and thus offers a bit more safety access.
The injection site can also be changed with
repeated injections to avoid structural changes
in the sclera. Thin areas of the sclera can be recognized by a bluish discoloration. Such areas
should be avoided. Possible peculiarities such
as a retinoschisis or a filtering bleb must also be
considered when choosing the site. An inferior
injection site has the advantage that, in the event
of a defensive reaction with Bell’s phenomenon,
the eye does not move towards the needle, thus
reducing the risk of lens injury.
190 K. Mayer et al.
with tweezers, one can also use the compass.
Here, the compass is used for distance measurement and simultaneous fixation of the eye, with
one tip pressed on the limbus and the second tip
pressed parallel to the limbus on the sclera. The
injection is then performed directly at the end
of the compass tip fixed on the sclera. To facilitate keeping the eye still, the patient can also be
given a fixation target if necessary.
The perforation is performed with the bev-
Fig. 18.2 Marking of the injection site. (© Bayer AG)
eled side and slightly obliquely to the sclera
lamellarly under even pressure. A stepwise
The injection site is marked with a caliper set
to 3.5 or 4 mm (Fig. 18.2). The marking is
done with light pressure from the caliper on the
sclera. The marking by the caliper then appears
as a small, dark gray, dot-like discoloration of
the sclera. Similar plastic markers are included
with disposable materials. If the injection is
too anterior, there is a risk of lens injury; if it
is too posterior, there is a risk of causing retinal
injury[1].
injection with displacement of the conjunctiva
was initially recommended. However, this has
not generally been adopted. After perforating the
sclera, the syringe is finally aimed at the center
of the eyeball (Fig. 18.4). This avoids damage to
the lens.
When administering a steroid implant, a
shallower injection angle can ensure a more
secure wound closure. With the larger diameter
of the Ozurdex cannula, a more reliable pain
reduction can be achieved with an additional
subconjunctival anesthesia before the injection.
18.7 Administration of the Injection
The patient should be informed that they may
see vitreous floaters in the form of “clouds.”
The globe is held with tweezers. Tenon’s capsule, episcleral tissue, and the conjunctiva are
firmly anchored to the sclera at the limbus.
There, the bulb can be safely guided with the
In the case of a small air bubble in the vitreous
cavity, the patient can be reassured about the
harmlessness of the “small black ball,” and that
the effect will disappear after one to two days.
tweezers (Fig. 18.3). The grip with the tweezers also simultaneously checks whether the
anesthesia is sufficient. There is always the risk
that the patient may startle and turn their head
or eye away. As an alternative to fixing the eye
Fig. 18.3 Guiding the eye with tweezers during the
injection. (© Bayer AG)
Fig. 18.4 Injection via the pars plana. (© Bayer AG)
19118 Intravitreal Injections
18.7.1 Post-Injection Checks
Following the injection, vision is checked with
hand movements to rule out a pressure-induced
central artery occlusion. A critical increase in
intraocular pressure is generally not to be feared
with an injection volume of 0,05 up to 0,1ml.
Nevertheless, a paracentesis lance should be
kept on standby to surgically reduce the pressure
via paracentesis if necessary. It should be noted
that in poorly controlled glaucoma, the small
amount of 0.05 up to 0,1 ml can still increase
postoperative intraocular pressure. Preoperative
administration of 250 mg acetazolamide intravenously or orally can prevent this. In some surgical centers and eye clinics, intraocular pressure
is checked after the injection using non-contact
tonometry. Additionally, retinal blood flow
(pulsation over the disc) and the position of the
medication implant in the vitreous cavity can be
checked with an ophthalmoscope if necessary.
Often, an eye bandage with or without antibiotic
ointment is applied afterward. However, many
surgical centers now forgo this. Postoperative
topical antibiotic treatment is generally no
longer recommended according to the guidelines of the DOG and the German Retinological
Society [2, 5].
has a pre-existing damage. The administration
of steroid medications often accelerates cataract
progression.
Mild vitreous opacities can be observed by
patients during an intravitreal injection. However,
severe vitreous hemorrhages are rare.
Endophthalmitis is the most feared complica-
tion after an intravitreal injection.
Depending on the study, the rate of endophthalmitis after intravitreal injections ranges between
0.019 and 1.4% [5, 7].
18.8 Aftercare
The surgeon’s last question to the patient is
always whether the postoperative follow-up is
ensured.
The first follow-up is usually conducted
between the second and fourth postoperative
day. Endophthalmitis is generally only visible
on the second or third postoperative day. With
steroid implants (Ozurdex® and Iluvien®), further checks to monitor intraocular pressure are
required during the postoperative course.
18.7.2 Possible Complications
Rarely, a residual effect of the local anesthesia
and a possibly compressing bandage on the cornea can lead to an erosion. For a small erosion,
viscous artificial tears and eye ointment are sufficient. In the case of a larger erosion, a bandage
lens or a simple soft daily contact lens provides
rapid relief. The patient is then scheduled for a
follow-up the next day.
A postoperative hyposphagma is commonly
observed and is generally harmless.
An iatrogenic cataract due to lens injury is
rare. However, if it occurs, the required cataract surgery is not simple, as the lens capsule
References and Further Reading
1. Bartz-Schmidt KU, Ziemssen F (2008) Intravitreale
Pharmakotherapie. Schattauer, Stuttgart
2. Bhatt SS, Stepien KE, Joshi K (2011) Prophylactic
antibiotic use after intravitreal injection: effect on
endophthalmitis rate. Retina 31:2032–2036
3. Bundesärztekammer (2018) Weiterbildungsordnung.
Berlin
4. DOG (2007) Empfehlung der Deutschen Ophthalmologischen Gesellschaft, der Retinologischen
Gesellschaft und des Berufsverbandes der Augenärzte
Deutschlands für die Durchführung von intravitrealen
Injektionen (IVI)
5. DOG (2013) Stellungnahme der DOG,
Endophthalmitis Prophylaxe bei intravitrealer operativer Medikamenteneingabe (IVOM)
6. Hansmann F, Kramer A, Ohgke H, Strobel H, Müller
M, Geerling G (2005) Lavasept als Alternative
192 K. Mayer et al.
für PVP-Iod zur präoperativen Antiseptik in der
Ophthalmochirurgie. Ophthalmologe 102:1043–1050
7. McCannel C (2011) Meta-analysis of endophthalmitis
after intravitreal injection of anti-vascular endothelial
growth factor agents: causative organisms and possible
prevention strategies. Retina 31:654–661
8. Wenzel M, Dick HB, Scharrer A, Schayan K, Agostini
H, Reinhard T (2020) Intraokulare Operationen:
Ergebnisse der Jahresumfrage 2019/2020 von
DGII, DOG, BVA und BDOC. In: 34. Kongress der
Deutschprachigen Gesellschaft für IntraokularlinsenImplantation, Interventionelle und Refraktive
Chirurgie. DGII, Mainz, S 55–58