[Comparative experimental morphological study of efficacy and safety of near-infrared and visible wave-length laser iridoplasty].

The features of interaction of laser radiation with iris tissue were determined in experimental morphological study. The potential of laser irradiation with different spectral characteristics for pupil ectopia correction is estimated. The results of morphometry showed effectiveness of near-infrared diode laser radiation, that presents as an iris contraction in coagulation region with minimal tissue trauma. This fact allows us to propose a near-infrared diode laser radiation as a treatment option for correction of pupil form and location. Alternatively visible wave-length laser showed to be less effective and more traumatic.

Thermic effects in the "vestibule" during laser stapedotomy with pulsed laser systems.

BACKGROUND AND OBJECTIVE: Apart from the ablation properties at the stapes footplate, the degree of thermic loading in the inner ear is important in determining the suitability of pulsed lasers for stapedotomy. The aim of the study is to compare the thermic effects in the vestibule with different pulsed laser systems. STUDY DESIGN/MATERIALS AND METHODS: Temperature increases and heat exchange processes in the fluid (physiological saline) were examined in a calorically and physiologically approximated cochlea model for applying the laser parameters effective in creating footplate perforations. RESULTS: With all systems, increases in the energy density, number of pulses, and thus resultant total energy lead to higher temperatures. In the effective energy density range, the highest temperature increases achieved with the requisite number of pulses at a distance of 2 mm behind the perforation are 26 degrees C with the Ho:YAG laser. The lowest temperature maxima are 5.5 degrees C with the Er:YAG and <5 degrees C with the Er:YSGG laser. The excimer laser, investigated at only one energy density, showed maximal temperatures of 10 degrees C. CONCLUSION: The Er:YSGG and Er:YAG laser can be applied in laser stapedotomy in a relatively broad energy density range without a risk of inner ear damage by thermic loading. On the other hand, the Ho:YAG laser is not recommended for stapedotomy because of the higher energy density and pulse rate required for sufficient perforation and the resultant higher temperature increases in the perilymph. Though likewise achieving perforations with only slight temperature increases in the fluid of the cochlea model, the excimer laser does not seem appropriate for stapedotomy because of the long period of heat exposure (ca. 60 s) due to the lower ablation rate at the stapes necessitating a longer application time.

Proliferaçäo vítreo-retiniana após retinopexia: influência da crioterapia / Proliferative vitreoretinopathy: the influence of cryoterapy

Foram analisados, de forma retrospectiva, 136 pacientes com descolamento da retina provocado por ruptura única, ou múltipla, pequena(s), localizada(s) no hemisfério retiniano superior, sem retinopatia vítreo-proliferativa pré-operatória (RVP), operados por pneumo-retinopexia (RP) ou introflexäo escleral setorial (IE), com crio ou laser no tratamento térmico das rupturas. O objetivo foi o de analisar a possível influência da crioterapia na gênese do PVR pós-operatório. Grupo I consistiu de 36 olhos operados por RP + laser; Grupo 2, 34 olhos, RP + crio; Grupo 3, 40 olhos, IE + laser; e Grupo 4, 25 olhos, IE + crio. O número de afácicos, a faixa etária, o número de quadrantes descolado, a acuidade pré-operatória e o tempo de seguimento foram semelhantes