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Sealed capsule irrigation device
could cut PCO after cataract
Sean
Henahan
in San Francisco, US
AN innovative device that allows sealed capsule irrigation could
offer a new way to reduce posterior capsule opacification (PCO)
following cataract procedures, according to a report at this year’s
meeting of the American Society of Cataract and Refractive Surgery.
The device, known as Perfect Capsule (Milvella), uses suction to
seal the lens capsule, allowing selective irrigation of the capsular
bag following phacoemulsification. The surgeon inserts the device
through the standard cataract incision after which it retains the
irrigating solution within the capsular bag by creating a vacuum
seal around the capsulorhexis, explained co-developer of the device,
Anthony J Maloof MBBS.
Dr Maloof recounted his early experience with the device. He inserted
the device successfully after cataract removal and cortical clean-up
through clear cornea incisions ranging from 3.2mm to 3.5mm in size.
He applied it to the anterior capsule using a 4.5mm capsulorhexis.
In each case he was able to irrigate the interior lens capsule without
significant leakage into the anterior chamber. In contrast, trypan
blue testing indicated that control eyes undergoing conventional
irrigation showed significant amounts of leakage.
Early clinical results in cases where patients received high risk
silicone lenses with rolled edges followed by sealed capsule irrigation
indicate that the device does appear to attenuate the activity of
lens epithelial cells. None of those patients have developed PCO.
“Looking at the early results, we are sufficiently encouraged
that we dramatically reduced anterior capsular changes and lens
epithelial selectivity. We also know it will require a controlled
clinical trial to find out exactly what we are doing and to evaluate
other pharmacological strategies. We feel this is a big step towards
the goal of eliminating PCO,” Dr Maloof said.
He added that the mechanical nature of the device has raised concerns
about zonular stress. No zonular problems have occurred so far.
Moreover, he said he had been unable to induce zonular dialysis
in test eyes. In cases of accidental forcible removal of the device
from the capsule during surgery, the zonules have remained in place,
he emphasised.
The Perfect Capsule holds the capsular bag by means of a toroidal
suction ring connected to a locking suction syringe. Fluid can be
injected into the empty capsule via an irrigation/aspiration port.
This significantly reduces the concentration of irrigation fluid
able to contact other ocular structures. The current protocol calls
for injecting trypan blue dye into the capsule to demonstrate capsular
integrity, he explained.
During surgery, the single-use device can be easily rolled or folded
in order to pass it through the standard corneal incision into the
eye. It can be positioned on the anterior surface of the capsule
using standard ophthalmic instruments, he noted.
Dr Maloof stressed that PCO has a significant impact on vision.
In addition to being an on-going problem in the general cataract
patient population, it occurs in 100% of paediatric cases and is
an emerging problem with accommodative IOLs.
“Posterior capsule opacification is the most common complication
of cataract surgery.
We designed the device to allow selective delivery of a pharmacological
agent to the lens epithelial cells and only those cells. This should
allow us to eliminate PCO while minimising the potential for collateral
ocular damage," he said.
A multicentre clinical trial which will evaluate the use of the
device with demineralised water is in the early stages. That trial,
which will include three centres in Europe, will seek to confirm
the PCO prevention capabilities of the device. Contraindications
for participation in the trial include the presence of weakened
zonules or anterior capsular tears.
He said that if the larger clinical trials support the initial results,
the device would probably be reserved in higher risk patients. If
the studies show that this approach effectively eliminates the lens
epithelial cells, it could eventually find much wider application.
The researchers also plan to test the device for delivery of drugs
including mitomycin C.
Dr Maloof recounted that he became interested in PCO following his
own experiences with cataract patients. He became frustrated when
he looked into patients’ eyes during postoperative examinations
and he could not get a clear view.
“I realised that if I couldn’t get a clear view inside
the eye I wouldn’t expect them to get a clear view looking
out of that eye. Similarly, when I saw with lens debris on an anterior
chamber lens, I couldn’t get a clear view until performing
a YAG procedure,” Dr Maloof explained.
This experience led him, in collaboration with colleagues, to develop
the sealed capsule approach. The researchers believe this approach
may prove a more simple and direct approach to PCO than developing
pharmacological strategies that are both effective and non-toxic.
The Perfect
Capsule device is available in the US, Europe and Australia.
Anthony J Maloof MBBS, MBiomedE, FRANZCO, FRACS
Sydney Eye Hospital, Sydney Australia
Email: amaloof@zip.com
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