Elsevier

Ophthalmology

Volume 107, Issue 7, July 2000, Pages 1389-1392
Ophthalmology

Comparison of erbium:yttrium–aluminum–garnet-laser vitrectomy and mechanical vitrectomy: A clinical study

https://doi.org/10.1016/S0161-6420(00)00123-8Get rights and content

Abstract

Objective

To evaluate the clinical usefulness of the erbium:YAG (yttrium–aluminum–garnet) laser for vitrectomy and to compare it with a conventional mechanical vitrectomy system regarding the intraoperative parameters.

Design

Prospective, randomized, clinical trial.

Participants

Thirty eyes of 30 patients underwent vitrectomy, 15 eyes in each group.

Methods

For mechanical vitrectomy, a commercially available vitrectomy unit was used. The operating parameters, cutting rate (7 Hz = 420 cpm), maximal suction force (300 mmHg), and aspiration flow (20 ml/min), were held constant. A newly developed erbium (Er):YAG laser unit and handpiece was used for laser vitrectomy with predetermined parameters for cutting rate (70 Hz = 4200 cpm), maximal suction force (50 mmHg), and aspiration flow (20 ml/min). Surgery parameters were recorded in real time and the operation was video recorded. The clinical follow-up time was a minimum of 3 months (average, 6.2 months; range, 3–9 months).

Main outcome measurements

The surgery time was comparable in both groups. During Er:YAG laser vitrectomy, the average suction force was significantly reduced (P < 0.001) compared with that during mechanical vitrectomy. The mean-square variation in suction as a measure to quantify the forces acting on intraocular structures during surgery was significantly smaller in the Er:YAG laser vitrectomy group (P << 0.001).

Conclusions

Erbium:YAG laser vitrectomy may provide a semicontinuous procedure. This technique minimizes periodical intraoperative forces and movements of intraocular structures and may provide, therefore, a safer vitrectomy.

Section snippets

Study groups

From November 1998 through January 1999, 30 eyes of 30 patients underwent vitrectomy by one surgeon (HP) at the Department of Ophthalmology, University of Dresden, Germany. The patients were recruited and randomly assigned to two study groups: Er:YAG laser vitrectomy (15 eyes) and mechanical vitrectomy (15 eyes). The demographic parameters of the patients are listed in Table 1.

Inclusion criteria for the two study groups were: (1) pathologic changes of vitreous in various degrees with and

Results

All 30 operations were uneventful and without complications. Additional scleral buckling (encircling band) was necessary in 6 cases, and 7 eyes needed silicone oil or temporary tamponade with SF6–air (four in the laser group, three in the mechanical vitrectomy group). In one eye in the laser group, a vitreous hemorrhage recurred.

Two surgical parameters, suction force and suction force variations, differed significantly in the two groups (Table 4). Because of the smaller adjusted maximal suction

Discussion

The key finding of this study is the clinical feasibility of a semicontinuous laser vitrectomy. A high cutting rate offers two options: (1) to accelerate the operation or (2) to make it smoother by lowering the suction force and, therefore, suction force variation. In this study, we followed the second strategy because small suction force variation induces small mechanical forces acting on intraocular structures, thus increasing the safety of the procedure. In this mode, the operation time

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Supported by the Brunenbusch-Stein Stiftung.

1

Dr. Mrochen is scientific consultant for Wavelight Inc., Erlangen, Germany. The other authors have no proprietary interest in the products described in this article.

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