Fig.1: Gas chromatographic Scan of non laser treated human nucleus. Fig. 2: Gas chromatographic Scan of laser treated human nucleus. Fig.3: Table of mass spectrograph scan of untreated nucleus ). Fig.4: Er:YAG cataract laser (Cut 2940 , InPro ) ).
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Fig. 2: Gas chromatographic Scan of laser treated human nucleus
Fig.3: Table of mass spectrograph scan of untreated nucleus)
Fig.4: Er:YAG cataract laser (Cut 2940, InPro))
Fig.5: Table of mass spectrograph scan of laser treated nucleus)
Fig. 6: Scan of reference untreated fragments(1A_3D.D)
Fig. 7: Scan of treated fragments (1A.D)
Supported by the Bio Chemical Institute of the University of Heidelberg
We thank Dr. U. Gehm of InPro GmbH, Hamburg for providing a laboratory modelof a Er:YAG cataract laser CUT 2940
Fig. 8: Scan of treated reference one day after (1A_4.D)
Toxicological Study of Laser-Induced Pyrolysis Products in Cataract Surgery
Specht H, Auffarth GU, Burk ROW, Voelcker HE
Phacoemulsification is the standard in cataract surgery. Ultrasonic phacoemulsification is highly effective and today standardizied. Concerns exist about the potential risks of ultrasonic energy delivered by the phacoemulsification tip on such nontarget ocular structures a s the corneal endothelium . Laser assisted cataractous lens removal has been investigated because of ergonomic considerations and the desire to minimize surgical invasiveness . Several laser technologies from the wavelength of UV to IR have been investigated there for. Different methods of nucleus cracking are capable mostly used is the Er:YAG laser in directly contact mode . In contrast to a standard phaco procedure only small openings within the corneal tissue are aimed for.
The purpose of this in vitro study is to evaluate the feasibility of toxicological risks  of the pyrolysis products  created by Er:YAG laser Treatment of lens fragment (assembled from clinical cataract patients).
To estimate the possibility of toxically pyrolysis products after laser treated cataractous nucleus under surgical conditions.
Materials and Methods
Used was a Er:YAG laser (Fig.4: InPro Hamburg, Germany; Type CUT 2940) in the normal spiking mode. The Er:YAG emits a radiation of 2.94 µm with a tuneable pulse lengths < 600 µs and a repetition rate < 10 Hz up to a maximal averaged power of 10 W. The laser was operated multimode with a uniform beam profile. At the tip, the laser beam was coupled into a zirconium fluoride fiber of 600 microns core diameter. The tip was used in contact mode to fracture and emulsify the nucleus. The energy per pulse delivered through the fiber was measured with a joule meter (PEM 10) at its high sensitivity of 81.5V/J. The fluence per pulse was calculated from energy per pulse and the measured spot diameter. The fluence was regulated by changing of the bank voltage. Parameters were: energy of35 mJ, repetition rate of 3 Hz and a puls length of 250 µs.
The lens fragments from 3 patients were used according to conventional method. The fragments of the lenses as well as the BSS liquid with rests of Healon GV were caught in a bag after ultrasound phaco. The samples were divided in each case in equal parts and a proportion was treated once with the Er:YAG laser. The untreated sample served as reference.
The analysis of the burn-up products was executed at a gas chromatograph and mass spectrograph. For this first screening a non polar column was used.
Thisfirst screening points showeda modification of thedetermined data from untreated material (Fig.1) to treatedmaterial (Fig.2). This modification could be observed in each case with the samples of the 3 patients. The data of the laser treated sample showed additional various, different masses could be detected. These mass numbers (Fig.3,5) are representing substances in the samples were detected. The measurements of the treated samples showed the same spectral mass again almost on the following day as the untreated samples (Fig.6-8).
The results of this investigation do not permit a conclusion over poisonous of the detected substances especially not an clinical reaction. The measurements with polar columns necessarily enable a very narrow-band detection of individual chemical products.
The investigation allows the statement that the detected substances are short-lived or volatile. A precise investigation of the detected substances is necessary to exclude the toxicologically potential of these laser induced products.
University of Heidelberg
Department of Ophthalmology
INF 400, D-69120 Heidelberg; Germany E-mail:Holger_Specht@med.uni-Heidelberg.de
American Sociaty of Cataract and Refractive Surgery