Jan Kasprzak

Procedures of optical control dedicated for laser welding process of biological tissues

In this contribution, an optical method of controlling the state of soft biological tissues in real time exposed to laser radiation is discussed. The method is based on the assumption that the change dynamics of the amplitude of the scattered diagnostic radiation (λ = 635 nm) is compatible with the change dynamics of the tissue inner structure exposed to the Nd:YAG laser radiation (λ = 1064 nm). In this method, the measurement of the tissue temperature is omitted. Exemplary results of the laboratory research on this method and an interpretation of the results are presented.

High-power Q-switched Er:YAG laser designed for medical applications

In this paper we report on a record 1.4 MW peak power, actively Q-switched Er:YAG laser operating at 2.94 μm. As a result of our experiment, at 3 Hz repetition rate, we achieved 91 ns pulses with 137 mJ energy. At higher repetition rate (10 Hz) the laser generated 100 ns pulses with 35 mJ energy. These results, according to our knowledge, are the best that have been ever achieved.

Ophthalmological LH-58 set with the holmium laser

The paper presents a description of a construction of the ophthalmological set LH-58 with the holmium laser. Results of preliminary medical tests of eye lens curvature correction carried out by means of this set are given.

Argon-krypton ion laser as light source for medical photocoagulation applications

Photocoagulators are one of the most popular laser devices in medicine. Due to different kind of interaction of particular wavelength range of laser light with live tissues, sources of laser radiation which can cover as much as possible of visible spectrum are still very wanted (see [1,2]). In last years it also can be observed the intensive developing works on new photocoagulation technique called “micropulse coagulation” [3,4]. The most critical feature of lasers for micropulse coagulation is the possibility of fast switching between two selected laser power values. It seems that the good proposal for these applications can be ion laser filled with argon-krypton mixture. Authors previously have indicated the possibility of improvement of generation conditions in this type of laser in presence of buffer gases [5,6] and with use developed by authors pulse supply regime [7,8]. These improvements allow to obtain output power values of most important argon and krypton laser lines in laser filled with mixture of both gases, similar to values available in laser filled with pure gases. Presented in this paper the following researches are concerned on verification of possibilities of use of the developed laser system in photocoagulation with possibility of use of the laser system in micropulse coagulation technique.

Ion argon-krypton laser for medical applications

Ion gas lasers filled with pure argon or krypton are often used in medicine. The number of possible medical laser applications are still increasing. Every type of application requires specific wavelength range. Due to number of available laser wavelengths of argon and krypton lasers, laser filled with mixture of both gases could be interesting universal medical laser source. However output power value of some interesting in medical point of view laser wavelengths may be insufficient in laser filled with mixture. Developed by authors quasi-continuous ion laser supply regime in connection with observed and described by authors the effect of laser power increase in presence of noble gas admixtures allows to achieve laser power satisfactory for certain medical applications but unavailable in typical ion lasers operated with standard continuous power supply regime.

Optical coherence tomography in the diagnosis of disorders of the anterior and the posterior eye

The paper discusses the applications of optical coherence tomography (OCT) in the diagnosis of eye disorders, i.e. OCT of the posterior segment of the eyeball and conditions that must be met to use OCT in the studies of the anterior chamber. Limitations of the technique and clinical requirements it must satisfy are also described.

Correction of senile entropion using holmium laser

Ninety-eight patients were included in clinical trials. They were divided into 3 groups, depending on the severity of lower lid inversion. Eighteen patients were included in the group with mild lid inversion; 59 patients had moderate lid inversion and in 21 patients the inversion was severe. Additionally, the patients were subdivided into two groups, according to their age - up to and above the age of 69 years. In both age groups, patients with moderate entropion predominated. All patients underwent photocoagulation of the lower lid. Post-operative wound healing took about 14 days. The effect was described as good when the position of the lid returned to normal with the lashes at an angle of about 45° to the free edge of the eyelid. When the position of the eyelid was normal with the lashes at an angle of about 60° or more to the edge of the lid and not rubbing against the globe, the effect was considered satisfactory. When the inversion of the lid was not corrected, the effect was unsatisfactory. Good effects were seen in 61% of patients, 21% of the patients demonstrated satisfactory effects and in 18% the outcome was unsatisfactory. The best results were observed in patients with mild entropion, aged 69 years and younger.

Histological evaluation of coagulation foci produced in the human lens with a holmium laser

We present the results of histological evaluation of human lenses treated with the holmium laser. The lenses, extracted at the time of extracapsular surgery for cataract, were placed in containers filled with Ringers solution. After treatment with laser-emitted radiation they were histologically evaluated. The formation of crater-like defects was found in the material studied.

Effect of holmium and erbium laser action on the human lens: an in-vitro study

We investigated the holmium and erbium lasers operating at the medium IR range, used for cataract surgery. The main advantage of these lasers action on biological structures is total absorption of radiation by superficial layers. During the study of the lens emulsification process we found that the mechanical properties of the lens nucleus were of crucial importance for the rate of emulsification. The soft lenses were fragmented and emulsified after 200-700 pulses, while the hard lens required 5000 or more pulses while complete emulsification was not achieved. The results are promising and show that the holmium and erbium lasers can be used for human lens emulsification during ECCE. For clinical purposes, however, it is necessary to construct a suitable fiberoptic tip to be used in cataract removal. It seems that lasers whose beam is in the medium IR range could be used in many ophthalmic operations.

Applications of the holmium laser in ophthalmology

The role of the holmium laser is gradually changing in contemporary ophthalmology. Although potentially applicable to the treatment of numerous ophthalmology disorders, it has not been yet widely used in clinical practice. However, intensive experimental studies are being conducted and the clinical effects are being evaluated.