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Careful surgical planning minimizes endothelial damage in cataract surgery
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STOCKHOLM, Sweden — Prevention of endothelial cell damage in cataract surgery requires accurate preoperative assessment and careful surgical planning, according to one speaker at the European Society of Cataract and Refractive Surgeons meeting.
"Endothelial cell loss after cataract surgery varies from 4% to 25% in the literature and has been demonstrated to continue for at least 10 years after the operation at a rate of 2.5% per year, which is four times the normal rate of the aging endothelium," said Rudy Nuijts, MD, of Maastricht University Hospital.
Preoperative conditions of compromised endothelial function, such as Fuch's dystrophy or post-penetrating keratoplasty, increase the risk of endothelial decompensation and should always be analyzed in view of the appropriate surgical planning and predictability of results, he said.
Intraoperatively, the use of well-balanced irrigating solution, resembling the natural components of the aqueous, is crucial to endothelial survival.
"I recommend the use of BSS (Alcon) and, in more difficult cases, of BSS Plus. Both solutions have been demonstrated to have a higher protective effect than Ringer's lactate," he said.
Dr. Nuijts also recommended the use Arshinoff's soft-shell technique, which combines two viscoelastic substances (OVD), one dispersive and one cohesive, to create a protective cushion between the endothelium and the space where surgical maneuvers are carried out.
"The use of this technique has been shown to significantly decrease endothelial cell loss (6.4% vs. 16.3%) compared with the injection of a single OVD," he said.
Small corneal incisions are correlated with a slightly lower rate of endothelial cell loss. However, scleral tunnel incisions are preferable in patients at risk of endothelial damage.
A review of a case series of different surgeons comparing coaxial and bimanual phacoemulsification showed that there is no significant difference in endothelial cell loss between the two techniques.
"What is important is the amount of ultrasound energy used. The introduction of micropulse and microburst in modern phaco machines has tremendously enhanced safety in regard to the endothelium," Dr. Nuijts said.
Torsional phaco was also demonstrated to produce lower levels of time and energy and less endothelial cell loss.
For nucleus fragmentation, the use of a chop technique with the appropriate chopping instruments, such as the Oshika Cobra Hook, prevents nuclear pieces from directly contacting the endothelium. "Mechanical contact with nucleus fragments is the principal cause of endothelial injury," he said.
Finally, surgeons should be aware of the toxic effects of topical antiseptic solutions, intraocular medications, preservatives and residuals of detergents on surgical instruments. All these agents can be the cause of toxic endothelial cell destruction.
"The guidelines for recommended cleaning procedures should be followed scrupulously, and we should consider restricting the utilization of reusable cannulas," Dr. Nuijts said.