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Preoperative adjustments based on cataract grade enhance phaco efficiency
J Cataract Refract Surg. 2010;36(2):242-246.
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Preoperatively customizing phacoemulsification parameters based on objective measurements of cataract density significantly reduced phacoemulsification time, a study showed.
"In clinical settings, it is common for surgeons to alter phaco settings intraoperatively according to the density of the cataract," the study author said. "It would be more efficient to set phaco variables preoperatively based on objective and reproducible cataract density results."
The study included 400 cataract patients assigned to one of two groups: 200 underwent cataract surgery with no change in parameters, and 200 underwent cataract surgery with settings adjusted preoperatively based on objective cataract grades.
All patients underwent phacoemulsification with the WhiteStar Signature platform (Abbott Medical Optics). The Pentacam Nucleus Grading System (Oculus) was used to grade cataracts.
Study data showed that effective phaco time was lower in the group that had settings adjusted preoperatively for all cataract grades. The difference was statistically significant for the lowest and highest grades.
The amount of balanced salt solution used was lower in the group with adjusted settings for all cataract grades.
In addition, needle time was significantly less in that group for grades 4 and 5 cataracts, the author reported.
In this article, Donald Nixon, MD, tries to relate the preoperative appearance of the cataract using Scheimpflug imaging. Grading the nuclear cataract by densitometry is an issue that has been analyzed before by us (see reference 8 of his references and also our reference: Alió JL, Schimchak P, Montés-Micó R, Galal A. Retinal image quality after microincision intraocular lens implantation. J Cataract Refract Surg. 2005;31:1557-60).
Dr. Nixon tries to adjust the fluidic and power parameters according to the grading of the cataract with the Scheimpflug images.
Scheimpflug images provide an idea about the density of the cataract. However, even though this grading system finds a good correlation with the LOCS III system, the hardness of the cataract is not well evaluated by this method. Indeed, there is a slight correlation but, on clinical grounds, this is rather far from being of predictive clinical value for cataract hardness.
The main merit of this paper is that it links surgery with preoperative grading of the cataract. Even though there is still a long way to go to establish the adequate grading system which correlates opacity and hardness to make a valid adjustment of the phaco parameters, indeed it is a step toward forward establishing a gradient about how much work the cataract removal will take by the surgeon. This may help to decide in difficult cases such as those in which there is a zonular instability, previous vitrectomized cases and other risk factors, to pre-estimate and to make an adequate prognosis and projection about how much work it will take to remove the cataract. This can be especially important when new technologies for cataract softening and removal appear on the future horizon of cataract surgery.
– Jorge L. Alió, MD, PhD
OSN
Europe Edition Board Member
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