By Clark L. Springs MD
This prospective study found that although torsional phacoemulsification reduced ultrasonography time and cumulative dissipated energy compared with longitudinal phacoemulsification in patients with Fuchs' endothelial dystrophy, both procedures showed similar effects on the cornea.
The authors randomized 26 patients (52 eyes) with Fuchs' endothelial dystrophy to cataract surgery with either longitudinal or torsional phaco. Age, nucleus density grade, and stage of Fuchs' endothelial dystrophy were similar between the two groups.
At six months postop, eyes that underwent torsional phaco fared better in terms of pachymetry and corneal volume at postop day one, but there were no long-term clinically significant differences between the groups in any of the outcome measures, including central corneal thickness (CCT), peripheral corneal thickness, corneal volume and BSCVA.
However, stabilization of corneal thickness occurred faster in the torsional group. Furthermore, both the cumulative dissipated energy and ultrasound time were reduced by 53 percent and 36 percent, respectively, in the torsional group compared with the longitudinal group.
Anterior segment OCT showed that a preoperative corneal of thickness of 620 microns or greater conferred a greater risk of corneal decompensation. Each additional 10 microns above 620 microns was associated with an odds ratio of 1.7 for corneal decompensation.
For me, this helps frame the discussion with Fuchs' patients in more practical terms. As cornea specialists, we can struggle with which procedure to offer (phaco or phaco/DSAEK) and what to tell patients their chances are of developing corneal decompensation with phaco alone. Obviously, one cannot interpret these data in wooden fashion (i.e., it is possible to have a ≥ 600 micron cornea) and other factors must be considered as well, such as amount of guttae and focal areas of corneal edema.
The authors add that there is a lack of data on normal CCT values in patients with Fuchs' endothelial dystrophy. Therefore, it is difficult to advise an absolute cutoff value of CCT for corneas at risk of decompensation.
They note that all important outcome parameters remained stable one month after cataract extraction. Therefore, ophthalmologists can advise patients who are not satisfied with their visual acuity postoperatively to wait until their one-month visit and then decide whether to undergo corneal transplant surgery. This decision does not have to be postponed until three or six months postoperatively.