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Laser cataract system no match for phaco yet
Improvement will come with time, but at present laser technology is slower than standard phaco, surgeon says.
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KOLOA, Hawaii — Laser cataract removal still has to come a long way before surpassing phacoemulsification, according to I. Howard Fine, MD.
While laser cataract systems will improve with time, Dr. Fine said, at present they leave something to be desired.
Dr. Fine outlined the differences between phaco and an erbium:YAG laser cataract system in efficacy, fluidics and safety here at Hawaii 2001, the Royal Hawaiian Eye Meeting, sponsored by Ocular Surgery News in conjunction with the New England Eye Center.
“I think we are very concerned with how much power is going into the eye,” Dr. Fine said. “One of the reasons we are interested in what we’re getting when we put a phaco hand piece in the eye is that there are new energy sources available and we need some way to compare those energy sources to what we’ve used traditionally with ultrasonic phacoemulsification.”
Energy and fluidics
---The Er:YAG Phacolase
is capable of removing up to 3+ grade cataracts in some cases.
Dr. Fine has a background in engineering and has been interested in the development of new cataract removal systems. He described the Er:YAG Phacolase (Asclepion-Meditec) and how it compares to ultrasound phacoemulsification.
He noted that ultrasound phaco is capable of removing all grades of nuclei. When addressing harder nuclei, a system that uses a lower amount of power would be an advantage.
According to Dr. Fine, the Asclepion-Meditec Phacolase is capable of handling 0 to 2+ grade nuclei, sometimes up to 3+.
“The great promise of laser phacoemulsification has always been a reduction in the energy into the eye,” Dr. Fine said. “I think it’s important for us to recognize that reducing energy into the eye is important. A recent paper from India showed that elevations in intraocular pressure postoperatively, related directly, independent of viscoelastic, to effective phaco time. So we know that power into the eye is doing more than addressing the nucleus.”
The Asclepion-Meditec laser uses less than 10 J of energy during a typical cataract removal. In a recent study he performed, Dr. Fine said, six conventional phaco systems used estimated energy of less than 10 J per case.
“We see there is not going to be a big advantage from laser with respect to energy into the eye. On the other hand, there is no thermal potential in the laser systems and so we can’t get a thermal injury to the incision,” he said.
When comparing fluidics in conventional phaco to the Er:YAG laser system, ultrasound has a definite advantage. “The fluidics in ultrasound systems have become inordinately sophisticated. We really use vacuum and flow as additional instruments in the eye now. We manipulate tissue with them,” Dr. Fine said.
Fluidics in the laser system is currently not as high-tech as in ultrasound machines.
“These ... systems are very much less sophisticated. The Asclepion-Meditec has a great tendency to clog. It’s very hard to occlude the tip. So we don’t use vacuum as we do in other systems,” he said.
Safety and clinical application
While ultrasound phaco machines scored better in efficacy and fluidics, the laser system and ultrasonic systems are somewhat similar in regard to safety.
“If we look at the safety, these are all similar,” Dr. Fine said. “There is low capsular rupture rate. There is low endothelial cell loss. Incision burns are increasingly lower now that we understand and use power modulations with ultrasound systems. But (burns are) impossible with (laser) systems.”
Clinical applications of the two types of machines are similar, but conventional phaco machines are quicker.
“Surgical time is much slower for laser than for ultrasound and that’s very important because time in the OR is convertible to cost in producing surgery,” Dr. Fine said.
He also said laser cataract systems have not so far proven less costly to purchase than conventional ultrasound.
One reason the Asclepion-Meditec laser is slower is that the energy is delivered through a fiber optic. Dr. Fine said it is difficult to occlude the tip, and he had to instead mash nuclear segments into the tip.
“So this procedure takes quite a bit of time. It’s not an uncontrolled procedure. We’re capable of maintaining a full chamber, but the incision is very tight because there is no heat generated by this system. This has really got a long way to go before it can compare with ultrasound as most of us are used to doing it,” he said.
“I believe all of these systems will improve increasingly, and that’s why they continue to generate enthusiasm on my part,” Dr. Fine said. “However, we can say this is slower than we’re used to seeing with conventional ultrasound technology.”
For Your Information:
- I. Howard Fine, MD, can be reached at 1550 Oak St., Ste. 5, Eugene, OR 97401; (541) 687-2110; fax: (541) 484-3883. Dr. Fine has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
- Asclepion-Meditec GmbH, manufacturer of the Phacolase system, can be reached at Prussingstrasse 41, Jena, D-07745 Germany; (49) 3641-65-3223; fax: (49) 3641-65-3660.