A longitudinal study was carried out in the laser unit of the Combined Military Hospital (CMH), Dhaka on 500 eyes of 500 patients who were treated with Neodymium-yttrium-aluminium-garnet (Nd:YAG) laser capsulotomy over a period of two and a half years. The aim of this study was to evaluate the visual acuity following Nd:YAG laser capsulotomy. The main entry criteria for this study were posterior capsular opacification (PCO) following Extracapsular Cataract Extraction (ECCE). The patients with corneal opacity, glaucoma, vitreous opacity, macular diseases, optic nerve diseases and any other retinopathies causing visual impairment were excluded from this study. Thirty six percent patients had pre-capsulotomy visual acuity 6/36 to 6/60, 32% patients had 6/18 to 6/24, 18% patients had <6/60 and 14% patients had 6/12. After seven days of capsulotomy 76% patients gained 6/12 or better vision. Eighty percent patients gained visual acuity of 6/12 with optical correction after thirty days. On the other hand, 64% patients had pre-capsulotomy near vision < N10 and 16% patients had N8. After capsulotomy near vision improved considerably. Four percent of the patients failed to improve vision following laser capsulotomy. It can be concluded that Nd:YAG laser capsulotomy in PCO can improve both distant and near vision, which can be augmented with optical correction after one month of laser surgery. Key words: Laser capsulotomy, Nd:YAG laser, visual acuity. DOI: 10.3329/jafmc.v5i2.4580 JAFMC Bangladesh Vol.5(2) (December) 2009, pp.29-31
In endoscopic submucosal dissection (ESD), the narrow gastrointestinal space can cause di±culty in surgical interventions. Tissue ablation apparatuses with high-power CO 2 lasers or Nd:YAG lasers have been developed to facilitate endoscopic surgical procedures. We studied the interaction of 808-nm laser light with a porcine stomach tissue, with the aim of developing a therapeutic medical device that can remove lesions at the gastrointestinal wall by irradiating a near-infrared laser light incorporated in an endoscopic system. The perforation depths at the porcine¯llet and the stomach tissues linearly increased in the range of 2-8 mm in proportion to the laser energy density of 63.7-382 kJ/cm 2 . Despite the distinct structural and compositional di®erence, the variation of the perforation depth between the stomach and the¯llet was not found at 808-nm wavelength in our measurement. We further studied the laser-tissue interaction by changing the concentration of the methyl blue solution used conventionally as a submucosal°u idic cushion (SFC) in ESD procedures. The temperature of the mucosal layer increased more rapidly at higher concentration of the methyl blue solution, because of enhanced light absorption at the SFC layer. The insertion of the SFC would protect the muscle layer from thermal damage. We con¯rmed that more e®ective laser treatment should be enabled by tuning the opto-thermal properties of the SFC. This study can contribute to the optimization of the driving parameters for laser incision techniques as an alternative to conventional surgical interventions.
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