One of the challenges of phacoemulsification surgery is operating within
the tight confines of the anterior segment of the eye. The volume of this
working space is less than 1 cm3, with delicate ocular structures
just millimeters away. The corneal endothelium and posterior lens capsule are
subject to irreparable damage should the fluidic balance induce anterior
Before surgery, the anterior chamber should be carefully examined using
the slit lamp microscope as well as measured via biometry. A shallow anterior
chamber can be seen in physiologically normal but small eyes with short axial
lengths as well as even smaller nanophthalmic eyes. In these eyes, the lens
calculations are best done with the Holladay 2 formula due to the anterior
effective lens position.
A shallow anterior chamber can be the result of a pathologic process
within the eye, such as glaucoma. In narrow angle glaucoma, the anterior
chamber is shallow due to the configuration of the anatomic angle. As cataracts
develop, the anteroposterior dimension of the human lens can increase, further
crowding the angle. In these eyes, cataract surgery not only improves vision,
but it can also help to treat the glaucoma by opening the angle of the eye.
Pseudoexfoliation is a disease process in which the zonules that support
the lens can become loose, allowing the lens-iris diaphragm to push the iris
forward and induce a shallow anterior chamber. Biometry of a pseudoexfoliation
eye that shows a normal to long axial length but a short anterior chamber depth
is a sign that the zonules will be particularly weak during cataract surgery.
|Pseudoexfoliation material is seen on the anterior lens capsule
in an eye with a shallow anterior chamber. The anterior chamber depth is 2 mm,
while the axial length is 25 mm. This indicates that the lens-iris diaphragm is
pushing the iris forward, due to excessive laxity of the zonules.
|An eye with an excessively deep anterior chamber and a
traumatic cataract should be carefully examined for damage to ocular
structures. In this case, approximately 6 clock hours of zonules are broken,
causing the lens to be displaced posterior. The fine iris pigment at the 9
o’clock position is embedded within a tongue of vitreous that has
Images: Devgan U
A very deep anterior chamber is most often seen in large myopic eyes
with long axial lengths. Although it can provide additional room during
phacoemulsification surgery, these eyes tend to have more elastic scleral
tissue and are prone to an overly deep anterior chamber during surgery. An
increase in anterior chamber depth is also seen in cases of trauma in which
ocular structures such as the zonules, lens or angle of the eye can become
damaged. Identification of the extent of ocular trauma ahead of time is helpful
in formulating an appropriate surgical plan.
With a shallow anterior chamber, performing a capsulorrhexis at the
beginning of the cataract surgery is difficult due to poor maneuverability and
lack of flattening of the anterior lens capsule. In most situations, this can
be addressed by injecting viscoelastics at the time of surgery. Cohesive
viscoelastics do a better job of creating and maintaining space. In that
regard, strongly cohesive OVDs such as Healon GV (1.4% sodium hyaluronate,
Abbott Medical Optics) or viscoadaptive products such as Healon5 (2.3% sodium
hyaluronate, AMO) tend to be the most effective choices. In rare cases, if the
anterior segment remains excessively shallow, a limited pars plana anterior
vitrectomy can be done to remove volume from the vitreous cavity. This allows
the anterior chamber to be further deepened during surgery but may pose
additional risks to the retina. Therefore, this technique should be used
cautiously. During phacoemulsification, the bottle height can be raised in
order to increase the infusion pressure into the anterior chamber, thereby
In large myopic eyes with excessively deep anterior chambers, the bottle
height can be lowered during surgery. However, the usual cause of the
excessively deep anterior chamber in these eyes is a reverse pupillary block.
The iris and anterior lens capsule form a tight seal that prevents infusion
fluid from equalizing with the posterior chamber. This can be resolved by
breaking the reverse pupillary block via lifting the iris with the chopper or
second instrument. For prolonged cases, a single nasal iris hook can be placed
in order to avoid an excessively deep anterior chamber for the entire surgery.
While the working space within the anterior segment of the eye is small,
careful evaluation and management of surgical parameters can allow us to
modulate its size and operate safely.
- Uday Devgan, MD, FACS, is in private practice at Devgan Eye in Los
Angeles, chief of ophthalmology at Olive View UCLA Medical Center and an
associate clinical professor at the UCLA School of Medicine. Dr. Devgan can be
reached at 11600 Wilshire Blvd., Suite 200, Los Angeles, CA 90025;
800-337-1969; fax: 310-388-3028; e-mail: firstname.lastname@example.org; Web site:
Devgan is a consultant to Abbott Medical Optics.