Shielding effect of the smoke plume by the ablation of excimer lasers.

BACKGROUND: Shielding and scattering effect of the smoke plume column ejected from the laser ablated material is a well-known phenomenon. Debris evacuation system of the excimer laser equipment removes these particles, but insufficient air flow can result in undesired refractive outcomes of the treatment. The aim of this study was to reveal the effect of the air flow speed on the actual ablation depth. METHODS: SCWIND AMARIS 500E flying spot excimer laser was tested in this study. A 150 µm phototherapeutic keratectomy (PTK) profile with 8 mm diameter was applied to the surface of polymethyl methacrylate (PMMA) plates. The velocity of the air flow was changed with adjustable air aspiration system. Ablation depth was measured with highly-precise contact micrometer. RESULTS: The prediction model was statistically significant, F(1,8) = 552.85, p < 0.001, and accounted for approximately 98.7% of variance of ablation (R2 = 0.987, R2adj = 0.986). Lower air flow speed resulted in a weaker ablation capability of the excimer laser. CONCLUSION: Air flow generated by the aspiration equipment is a key factor for the predictable outcomes of refractive treatment. Therefore, manufacturer inbuilt debris removal system should be regularly checked and maintained to ensure proper clinical and predictable refractive results.

[Impact of crosslinking on corneal epithelial healing]. / Crosslinking kezelés hatása a szaruhártya hámosodására.

INTRODUCTION AND AIM: To analyse the effect of crosslinking (CXL) on corneal epithelial healing. PATIENTS AND METHOD: 39 keratoconus patients following CXL and 11 patients following PRK were enrolled in this study. 21, 45 and 69 hours after CXL and 16, 37 and 61 hours following PRK slitlamp photographs were taken using fluorescein staining and the size of the epithelial defect and the time of epithelial closure was determined. As the observation time-points differed in both groups, the size of the epithelial defect following PRK was calculated for the time points used for analysis of CXL patients. These data were compared using chi-quadrat test. RESULTS: Following crosslinking, epithelial closure occured within 3, following PRK within 4 days. In the area of epithelial erosion 45 and 69 hours after CXL or PRK treatment statistically significant difference (p = 0.005 and p<0.001) was verified. CONCLUSION: Our results show beneficial effect of crosslinking on corneal epithelial healing. Orv. Hetil., 2017, 158(10), 376-379.

[Relationship between corneal surface temperature and air flow conditions during refractive laser eye surgery using three different excimer lasers]. / A szaruhártya felszíni homérséklete és légáramlási viszonyainak alakulása refraktív célú lézeres beavatkozás közben három különbözo típusú és ismétlési frekvenciájú excimer lézerberendezésnél.

INTRODUCTION: Thermal conditions during photorefractive keratectomy might be an important issue related to the corneal wound healing and long-term outcomes. AIM: Authors tried to find out the importance of temperature conditions during the treatment. METHOD: One eye of 90 patients has been included into the study. Photorefractive keratoctomy was applied with Carl Zeiss MEL 70, MEL 80 and Wavelight Allegretto excimer lasers. EBRO TLC 730 infrared thermometer was used for the measurement of surface temperature of the cornea before epithelial removal, as well as before and after the treatment. Average age of the patients was 25.5 ± 3 yr. Average myopic correction was -3.2 ± 0.8 Dpt. RESULTS: Statistically significant difference was found in temperature change between MEL 80 and the other two types of excimer laser devices. CONCLUSIONS: Different air flow conditions of the smoke removal system might have an influence on changes of the corneal temperature during treatment, but the refractive results were not influenced by this issue. Orv. Hetil., 2016, 157(43), 1717-1721.

Idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) and electrosensibility (ES) - are they connected?

INTRODUCTION: The tendency of experiencing unpleasant symptoms in the proximity of working electric devices is called idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF). Evidence about psychophysiological backgrounds of the phenomenon (i.e., detection ability and mechanisms of symptom generation) is not yet conclusive. METHODS: Participants of the provocation experiment were 29 individuals with self-reported IEI-EMF and 42 control persons. Participants completed questionnaires (symptom expectations, somatosensory amplification - SSAS, modern health worries radiation subscale - MHW-R), and attempted to detect the presence of 50 Hz 0.5 mT magnetic field (MF) directed to their right arm in 20 subsequent 1-min sessions. Heart rate was also recorded and various indices of heart rate variability (HF, LF/HF, SDNN) were calculated. RESULTS: Using the methodology of the signal detection theory, individuals with IEI-EMF as opposed to the control group showed a higher than random detection performance (d' differed slightly but statistically significantly from zero), and they used a significantly lower criterion (ß value) when deciding about the presence of the MF. Detection sessions followed by correct decisions (hits or correct rejections) were characterized by higher HRV (SDNN and HF indices) than periods followed by errors (misses or false alarms). Previous expectations and affiliation to the IEI-EMF group were significant predictors of symptoms reported following exposure. IEI-EMF was closely related to MHW-R and SSAS scores. CONCLUSION: Detection of MF might be possible for people with IEI-EMF to some extent. Although heightened sensibility to MFs may play a role in the development and/or in the perpetuance of the IEI-EMF phenomenon, symptoms attributed to the MF seem to be mainly of psychogenic origin.