[Erbium:YAG laser vitrectomy: temperature measurements in different replacement materials].
BACKGROUND
The erbium:YAG laser has the potential of being used routinely for vitrectomy because of the excellent quality of liquefying vitreous structures and the low vacuum forces required. However, the use of silicone oil and perfluorocarbon may lead to unwanted temperature increases in the microsurgery probe. The aim of this work was to investigate this side effect.


METHODS
Different replacement materials such as water, methocel, silicone oil and perfluorocarbon were used in a simple eye model. The temperature increase during laser application was measured by means of thermocouples. The maximum temperature increase and time decay were derived with and without aspiration from these time-resolved measurements. The average power at the distal end of the microsurgery probe was chosen to be 1 W.


RESULTS
The temperature increase with aspiration in water was found to be significantly smaller than all other replacement materials. Interruption of aspiration leads to a critical temperature increase of approximately 14 K; however, this increase occurred very slowly (decay time 200 s). A comparable result could be observed for methocel, which was used to simulate condensed vitreous structures. In perfluorocarbon and silicone oil we measured a far higher increase in temperature of up to 130 K within a few seconds. Furthermore, small remnants of carbonized materials can be seen in the microsurgery probe after laser application.


CONCLUSIONS
The temperature increase during erbium:YAG laser vitrectomy in water can be considered to be harmless for other intraocular structures. However, insufficient aspiration or increased vitreous condensation leads to increased temperature in the microsurgery probe. Our results demonstrate that the use of erbium:YAG laser vitrectomy in materials such as silicone oil or perfluorocarbons is contraindicated.
Mrochen
M
M
Universitäts-Augenklinik Dresden.
Riedel
P
P
Kempe
A
A
Seiler
T
T
D000075202:Contraindications; D005466:Fluorocarbons; D006801:Humans; D053685:Laser Therapy; D008747:Methylcellulose; D008953:Models, Anatomic; D008962:Models, Theoretical; D012307:Risk Factors; D012827:Silicone Oils; D013696:Temperature; D014821:Vitrectomy / Q000009:adverse effects / Q000379:methods*; D014867:Water
D005466:Fluorocarbons; D012827:Silicone Oils; D014867:Water; D008747:Methylcellulose