Injection: Maximizing the Benefits and Minimizing the Risks
DONALD J. D'AMICO, MD
With the recent Food and Drug Administration
approval of Macugen (pegaptanib sodium; Eyetech/Pfizer Inc, New York, NY) for the
treatment of neovascular AMD and the investigational use of triamcinolone acetonide
in patients with AMD and diabetic retinopathy, retina specialists are presented
with the decision to incorporate the therapeutic use of intravitreous injections
into their daily practice. Intravitreous injection has several advantages over other
routes of drug administration especially for disorders affecting the posterior segment
of the eye. The most significant is the avoidance of systemic toxicity. The drug
is introduced precisely to the target tissue and therapeutic intraocular concentrations
are achieved soon after the injection. The blood-ocular barrier is bypassed allowing
the use of agents that would be excluded due to their systemic effects at the doses
that would be otherwise necessary.
During the past 20 years, the
use of intravitreous injection has gained increasing acceptance. It began as the
pathway for the successful treatment of endophthalmitis and is now used extensively
for pneumatic retinopexy in the treatment of primary rhegmatogenous retinal detachment.
Nevertheless, it is not without risks, and these risks include retinal toxicity
from injected agents as well as mechanical damage to the retina and lens.1
Other risks of significance include endophthalmitis, acute intraocular pressure
(IOP) rises, intraocular inflammation, retinal detachment, cataract, intraocular
lens dislocation, hemorrhage, retinal vascular occlusion, cystoid macular edema,
and hypotony. Injection-related pain, inconvenience to the patient, and, for some
agents, the need to repeat the injection frequently in order to maintain effective
drug concentrations are other disadvantages of intravitreal injection. Despite these
limitations, proper technique and care in adhering to aseptic procedures have allowed
safe administration of new intravitreous therapies with high patient acceptance
GUIDELINES FOR SAFE INTRAVITREOUS
With anticipation that the number
of intravitreous injection indications would grow based on promising results from
ongoing clinical studies, a group of retina specialists recognized the need to identify
specific strategies for the delivery of intravitreous injection that reduce risks
and improve outcomes. In 2004, this panel developed practice guidelines based on
its review of published and unpublished studies and case series regarding intravitreous
injection.3 It must be emphasized that these guidelines should be viewed
as suggestions and not rules, because the data that entered into their formulation
is far from complete. Nevertheless, the guidelines provide a series of recommendations
concerning intravitreal injection technique for a broad range of indications. The
panel's key recommendations are summarized in the Table and discussed below.
Prior to performing an intravitreous
injection, the physician should conduct a thorough risk assessment and manage any
disorders, conditions, or abnormalities. Since the use of povidone-iodine is recommended
for antisepsis during the procedure, it is important to not exclude patients who
give a vague or uncertain history of allergy. Allergies to povidone-iodine are extremely
rare; in patients reporting a history of allergy to iodine, a skin-patch test may
be performed, but it is quite rare to find a positive result, and in almost all
cases, povidone-iodine may be used. Active external infections, including
should be treated, and the injection should not be administered under any circumstances
until the infection is cleared. Any eyelid abnormalities such as entropion and the
like should be considered to be a risk factor for the development of
and warrant increased attention and follow-up.
After careful exclusion of infected
patients, and the extensive and liberal use of povidone-iodine, the third most important
item is the use of a lid speculum to keep the needle from contacting the lashes.
As part of universal precautions, the use of gloves and draping of the surgical
field are appropriate, but draping of the periorbital region and eyelashes are not
essential. The physician may use discretion with regard to the use of preinjection
antibiotics. Excessive lid manipulation should not be performed. If preinjection
globe softening is desired, pressure should be applied directly to the globe, not
to the lids or adnexa; in short, the meibomian gland material should not be massaged
on to the ocular surface.
Pupillary dilation is the preferred
method of achieving adequate visualization. Topical anesthetics should be applied
according to standard practice, and supplemental subconjunctival anesthetic or topical
gel may be administered as well, and probably will be appreciated by the majority
of patients. Before the injection is administered, povidone-iodine drops or wash
should be applied directly to the ocular surface, lid margins, and lashes using
a sterile applicator, drops, or a flush. As mentioned, the use of a speculum is
recommended. After the speculum is in place, an additional drop of povidone-iodine
should be applied to the intended injection site. The injection should be placed
through the pars plana in the inferotemporal quadrant 3.0 mm (pseudophakic eyes)
to 4 mm (phakic eyes) from the limbus. A 27-g needle or smaller with a length of
0.5 inch to 5/8 of an inch is preferred, and the needle should be inserted 6 mm
toward the eye's center.
Antibiotics may be administered
postinjection at the physician's discretion, but within 72 hours of treatment. Typically,
several drops of a topical fourth-generation quinolone are given, and many physicians
use a day or 2 of additional postinjection topical antibiotics, although the data
for their benefit is nonexistent. For the typical patient, a 0.1 mL injection will
produce only a very transient pressure rise, and the patients should be monitored
for the return of light perception vision within a minute or 2, as well as examined
for return of perfusion of the optic disc by ophthalmoscopy. Paracentesis is to
be avoided in virtually all cases, and even applanation tonometry may be avoided
post injection, since both of these items may pose additional risk of infection,
and are invariably unnecessary. Patients and caregivers should be educated to recognize
the symptoms of endophthalmitis, retinal detachment, and intraocular hemorrhage,
and they must be instructed to call at once if they develop pain or loss of vision.
It is useful to have all patients call in to the physician's office on the first
post injection day simply to verify that they are free of any worrisome symptoms.
In addition, all patients should be contacted for a second time within 1 week of
the procedure, again perhaps by phone, with further follow-up dictated by their
individual needs. However, most patients will not require an interval examination.
Over the next few years, the rapid
and substantial expansion of clinical applications using intravitreous injection
can be expected given the increasing body of evidence that demonstrates the safety
and benefits of access through the vitreous. Implementation of these
guidelines will allow ophthalmologists to benefit from the clinical experiences
of their peers to reduce the risks associated with intravitreous injection.
Donald D�Amico is professor of ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA. He is a consultant to Eyetech Pharmaceuticals, Alcon, and Iridex. He can be reached by e-mail at
1.�Jager RD, Aiello LP, Patel SC, Cunningham ET Jr. Risks of intravitreous injection: a comprehensive review. Retina. 2004;24:676-698.
2.�Gragoudas ES, Adamis AP, Cunningham ET Jr, Feinsod M, Guyer DR; VEGF Inhibition Study in Ocular Neovascularization Clinical Trial Group. Pegaptanib for neovascular age-related macular degeneration. N Engl J Med. 2004;351:2805-2816.
3.�Aiello LP, Brucker AJ, Chang S, et al. Evolving guidelines for intravitreous injections. Retina. 2004;24(Suppl 5):S3-S19.
strongest panel recommendations were:
Screen patients for disorders, conditions, or abnormalities that may increase risks.
with active lid or ocular adnexal infection.
Use gloves for the
massage of the eyelids either pre- or postinjection (to avoid expressing meibomian
In patients with
glaucoma: monitor/manage IOP both before and after injection; avoid paracentesis
(prophylactic or postinjection) unless absolutely necessary.
Dilate the pupil unless otherwise contraindicated; single-use or fresh bottles are
Use adequate anesthetic
(topical drops and/or subconjunctival injection [single-use bottles recommended]).
on the ocular surface, lid margins, and eye lashes.
Use a lid speculum
to avoid contamination of the needle with the eye lashes or eyelid margin.
Educate patients and caregivers to recognize symptoms of endophthalmitis, retinal
detachment, and intraocular hemorrhage.
within 1 week of the injection to inquire about vision loss and complications.
Recommendations for which
there was no clear panel consensus were:
Use of a sterile drape.
Use of immediate pre- or postinjection antibiotics (little evidence to support
their value as prophylaxis for endophthalmitis).
Use of an additional
10-cc povidone-iodine as a preinjection flush.
Technique for monitoring
postinjection IOP in the eye without glaucoma or underlying optic disc disease (applanation tonometry vs. verifying optic disc perfusion
Retinal Physician, Issue: July 2005