Eruption of the nevado del ruiz volcano, Colombia, on 13 november 1985: tephra fall and lahars.

A small Plinian eruption of the Nevado del Ruiz volcano in Colombia ejected 3.5 x 10(10) kilograms of mixed dacite and andesite tephra on 13 November 1985, with a maximum column height of 31 kilometers above sea level. Small pyroclastic flows and surges, generated during the initial stage of the eruption, caused surface melting of approximately 10% of the volcano's ice cap, leading to meltwater floods. The erosive floods incorporated soils and loose sediments from the volcano's flanks and developed into lahars, which claimed at least 25,000 lives.

[Macular hole surgery without postoperatory <> down positioning. Pilot study]. / Cirugía de agujero macular sin posición <> postoperatoria. Estudio piloto.

PURPOSE: To evaluate the visual and anatomical outcomes of macular hole surgery using phacoemulsification, vitrectomy and intraocular gas tamponade without the use of postoperative face down positioning. METHODS: Phacoemulsification with an intraocular lens implant, followed by vitrectomy with internal limiting membrane peeling and perfluoropropane (C3F8), was performed in patients with stage 3 or 4 macular holes. After surgery, patients had to avoid the supine position for 15 days. Patients with a gas level <50% during the first week had a fluid-gas exchange. Visual acuity and closure of the macular hole were evaluated after 1 year of follow-up. RESULTS: 20 eyes of 20 patients, aged 60 to 75 years (median age 68 years), were included in this study. The best initial visual acuity ranged from 0.05 to 0.13 (ETDRS), with the median being 0.06. The final visual acuity was 0.05 to 0.30 with a median of 0.10. A statistically significant improvement (p=0.001, Wilcoxon) was found. The anatomic postoperative results revealed 90% (n=18) of the macular holes were closed while 10% (n=2) were not. CONCLUSIONS: Macular hole surgery has, in general, good results and patients can achieve improvement in their visual acuity without the need for uncomfortable and unbearable post operative posture positions.

Radial optic neurotomy for ischaemic central vein occlusion.

BACKGROUND/AIMS: Ischaemic central retinal vein occlusion (CRVO) accounts for 20-50% of all CRVO. No treatment has been proved to be effective. The efficacy of radial optic neurotomy (RON) was evaluated in eyes with ischaemic CRVO. METHODS: 10 patients with ischaemic CRVO underwent RON. After pars plana vitrectomy, a microvitreoretinal blade was used to incise the scleral ring, cribriform plate, and adjacent sclera at the nasal edge of the optic disc. Best corrected visual acuity (BCVA), intraocular pressure (IOP), fluorescein angiography (FA), multifocal electroretinography (mfERG), and optical coherence tomography (OCT) were measured preoperatively and at 1, 3, and 6 months postoperatively. RESULTS: No visual improvement was noted in the eyes that underwent RON. FA and mfERG showed no increase in retinal perfusion or retinal function postoperatively. Mean macular central thickness changed from 841 (SD 170) mum preoperatively to 162 (SD 34) microm at the sixth postoperative month. One patient had retinal central artery perforation intraoperatively. One patient developed neovascular glaucoma. CONCLUSION: RON in ischaemic CRVO did not improve visual function (by mfERG) or visual acuity although macular thickness did improve. This technique may be associated with potential risks. Randomised studies are needed to corroborate these results.

Subretinal, viscoelastic-assisted, endoscope-guided photothermal ablation of choroidal neovascular membranes by Erbium:YAG laser.

BACKGROUND AND OBJECTIVE: The efficacy of endoscope-guided Erbium:YAG laser, assisted by viscoelastic macular detachment, in subretinal ablation of choroidal neovascular membranes (CNVs) is evaluated. PATIENTS AND METHODS: A high-repetition, midinfrared erbium:YAG laser was used subretinally to ablate CNVs in 2 patients. Ablation followed pars plana vitrectomy and macular retinal detachment using a viscoelastic substance, and was guided by a high resolution endoscope. RESULTS: Visual acuity improved from 6/90 to 6/20, six months after treatment in 1 patient, and from finger counting from 1 meter to 6/30, three months after treatment in the other. The membranes showed no angiographic signs of activity postoperatively. However, a zone of stippled hyperfluorescence appeared in both patients, corresponding with the macular detachment area. This gradually diminished in size in both patients. CONCLUSIONS: The surgical procedure was found effective in our preliminary research. The use of viscoelastic substance and endoscope is felt to contribute to the favorable outcome. The cause and significance of the retinal pigment epithelium damage are yet to be determined.

[Bilateral macular cysts secondary to electric current strike. A case report]. / Quistes maculares bilaterales inducidos por descarga eléctrica. Presentación de un caso.

OBJECTIVE: To report the clinical and tomographic findings in a case of maculopathy secondary to high-tension electric current strike. CASE REPORT: A 27-year-old male refers a reduction in his visual acuity after electric strike. Visual acuity was 0.05 in both eyes. Circular reddish macular lesions measuring 400 micro m in RE and 200 micro m in LE were evident. Optical coherence tomography (OCT) showed intraretinal foveal cysts. At the third month follow-up visit, visual acuity had improved to 0.4 in RE and 0.5 in LE. Clinical and tomographic evaluation showed a reduction of the foveal cysts. DISCUSSION: Electricity affects retinal pigment epithelium and retina by thermal denaturation. OCT provides a conclusive diagnosis.

Successful erbium: YAG laser-induced chorioretinal venous anastomosis for the management of ischemic central retinal vein occlusion. A report of two cases.

BACKGROUND: Central retinal vein occlusion (CRVO) is a disorder with potentially blinding complications, particularly when associated with retinal ischemia. There is no reliable treatment for ischemic CRVO. METHODS: We developed a new approach for ischemic cases of CRVO consisting of vitrectomy, posterior hyaloid detachment, and four erbium:YAG laser-induced chorioretinal anastomoses, one in each quadrant. RESULTS: We report two cases of ischemic CRVO treated with this approach, with initial visual acuity of count fingers at 30 cm and hand movements respectively. After the surgery, there was resolution of hemorrhages and macular edema and visual improvement to 20/400 in the first case and to 20/180 in the second case. In both cases, there was successful creation of chorioretinal anastomoses, and there was no anterior segment neovascularization or other complications related to the surgery. CONCLUSION: This treatment shows promise in the management of the ischemic cases of CRVO, and further evaluation is justified.