Biomedical subjects

J M Heisler

Publications and source records attributed to J M Heisler.

3 recordsLinked to original sources

PubMed2002

[In vivo measurement of temperature during phacoemulsification].

BACKGROUND: Based on our experience of in vitro measurements of temperature in the anterior chamber in 1994 we designed a new spatula with an integrated probe that enabled us to measure temperature continuously during phacoemulsification without any surgical effort. METHODS: We measured the temperature in the anterior chamber during 50 cases of phacoemulsification. Depending on the indications, we used different energy modes (0-100%) and pulse modes ranging from 3 to 10 pulses per second or continuous ultrasonic output. Different viscoelastic substances were also used. RESULTS: The average temperature in the anterior chamber was 30 degrees C and adapted to the temperature of the irrigation fluid within seconds as soon as irrigation was started. During phacoemulsification each ultrasonic output causes an increase of temperature. In the case of continuous mode, the maximum rise in temperature was 3.5 degrees C. When the pulse mode was used the temperature increased up to 1.7 degrees C. It is important to note that one single pulse may increase the temperature by 0.8 degree C close to the phacotip. The rise of temperature correlated with the viscosity of the viscoelastic substance used. CONCLUSIONS: The new probe proved to be a practical device to monitor temperature in the anterior chamber during phacoemulsification. Up to now we did not encounter any critical degrees of temperature but it should be pointed out that a functional irrigation unit, the use of pulse mode or permanent ultrasonic output and in particular the type of viscoelastic material used are all important parameters influencing the rise of temperature during phacoemulsification. Further experience and results obtained with the new probe will be reported in the future.

Anterior Chamber↗

PubMed2000

[Long-term results of combined glaucoma and cataract surgery. Intraocular pressure and visual acuity follow-up].

BACKGROUND: The aim of this investigation was to ascertain the long-term results of intraocular pressure and visual acuity after combined glaucoma and cataract surgery. PATIENTS AND METHODS: Between 1994 and 1997, 65 eyes underwent Pham's sclerectomy and at the same time 65 eyes underwent Elliot's trephination with scleral flap. Both procedures were combined with phacoemulsification and implantation of a posterior chamber lens. The mean follow-up was 21.9 +/- 11.0 months. RESULTS: The IOP of eyes that underwent Pham's sclerectomy decreased from 21.4 +/- 3.3 mmHg to 14.9 +/- 2.7 mmHg and of eyes that underwent Elliot's trephination from 24.6 +/- 7.3 mmHg to 15.8 +/- 2.6 mmHg. Thirty percent of the eyes with Pham's sclerectomy and 25% with Elliot's trephination required an additional medication. In both procedures the overall visual acuity increased by three lines. CONCLUSIONS: These results of combined glaucoma and cataract surgery confirm their efficiency. From the economical aspect, combined glaucoma and cataract surgery has gained increasing significance.

Aged↗

PubMed1995

[Experimental study of the temperature during phacoemulsification].

UNLABELLED: Reports on thermal burns during phacoemulsification motivated us to perform an experimental study on the temperature gradient [2,7]. A special measurement technique was developed that enable us to record temperatures in 0.1 s and to document these measurements and interpret them. The experiments were conducted in enucleated pig eyes, as well as in a constructed model of the anterior chamber. Using 500 such measurements, we discuss and demonstrate the influence of the volume of the anterior chamber, the adjustment of the phacoemulsification, the presence of viscoelastic material, the reflection of ultrasonic power on the lens, and insufficient or interrupted irrigation and/or aspiration. RESULTS: An analysis of the measurements showed that within 8 s extremely high temperatures developed. At the phacosleeve, temperatures of more than 100 degrees C were recorded. Measurements around the phacotip also showed high temperatures resulting in tissue degeneration, especially with simultaneous application of viscoelastic material and/ or the presence of a hard nucleus. When pulse modulation is applied or power reduced, temperatures drop to less than 50%. CONCLUSIONS: The main factor behind the development of high temperatures is the breakdown of irrigation. The danger of phacoburns increases by application of viscoelastic material, reduced volume of the anterior chamber when there is a hard nucleus and high ultrasonic power with no pulse.

Animals↗