A 3-dimensional finite element method for groundwater flow and containment transport

A code was written to model groundwater flow and to solve for contaminant transport in variably saturated porous media using the Finite element method. The numerical code was written in FORTRAN 77. The GWGRID program was used for mesh generation. This numerical model was applied to two nuclear waste sites; Two test cases were run. The first one was the Savannah River Site, located in Aiken, South Carolina (SRS). The SRS has been storing radioactive waste material for several decades. Numerous studies as well as field data for the properties of the surrounding soil and contaminant presence have been conducted. Results of a two dimensional case were compared with the three dimensional case for a period of fifteen years; The second test case was the Yucca Mountain Repository Site (YMP), which is being evaluated as a future site for storing radioactive nuclear-waste. Results from the 3-D simulation were compared to results from a two-dimensional model. This simulation was run for a period of ten thousand years; The purpose for running the 3-D simulation was to get more realistic results than the 2-D calculations. The simulations were mainly run on the Convex and the Cray computer. The results seem to be fairly accurate as compared to the work done at the sites

26-G needle-assisted sutureless glueless intrascleral haptic fixation for secondary ciliary sulcus implantation of three-piece polymethylmethacrylate intraocular lens during penetrating keratoplasty

AbstractAfter tenotomy adjoining 3 o'clock and 9 o'clock limbus, 3-mm-wide partial-thickness scleral tunnels are created at these two diametrically opposite points 3 mm from the limbus such that they reach up to a distance of 1.5 mm from the limbus. Two ab externo sclerotomies are created using 26-G needles on the bed of these partial-thickness scleral tunnels. Precaution is taken to ensure that the positions of the sclerotomies are diagonally opposite each other. A scleral niche is made using a 26-G needle to accommodate the intraocular lens (IOL) haptic later. A 7.5-mm trephine is used to excise the corneal button, and anterior vitrectomy is performed. The haptic of a three-piece polymethylmethacrylate IOL is docked in a bent 26-G needle. It is then pulled out under the partial-thickness scleral tunnel and placed securely in the scleral niche opposite to the haptic. An 8-mm donor corneal button is sutured in place using 16 equidistantly placed 10-0 nylon interrupted sutures

Posterior migration of Ahmed glaucoma valve tube in a patient with Reiger anomaly: a case report

BACKGROUND: To describe, a yet non-documented complication of GDI surgery (glaucoma drainage incision surgery) - anterior to posterior segment migration of Ahmed Glaucoma Valve (AGV) tube. CASE PRESENTATION: We report a young 9 year old boy, diagnosed with refractory glaucoma with Reiger anomaly. History included of poor vision in both eyes, left more than right with glare since childhood. He underwent GDI surgery with AGV implantation following which he developed posterior migration of AGV tube. The detailed ocular history, ophthalmic findings, clinical course, surgical management and development of the posterior tube migration is discussed. CONCLUSION: Posterior Migration of AGV tube has yet not been described. Also there is a role of expectant management of the complication in this case as evidenced by the benign course of events

Insertion of a foldable hydrophobic IOL through the trabeculectomy fistula in cases with Microincision cataract surgery combined with trabeculectomy

BACKGROUND: The use of conventional foldable hydrophobic intraocular lenses (IOLs) in microincision cataract surgery (MICS) currently requires wound enlargement. We describe a combined surgical technique of MICS and trabeculectomy with insertion of a foldable IOL through the trabeculectomy fistula. METHODS: After completion of MICS through two side port incisions, a 3.2 mm keratome is used to enter the anterior chamber under the previously outlined scleral flap. An Acrysof multi piece IOL (Alcon labs, Fort Worth, Tx) is inserted into the capsular bag through this incision. The scleral flap is then elevated and a 2 × 2 mm fistula made with a Kelly's punch. The scleral flap and conjunctival closure is performed as usual. RESULTS: Five patients with primary open angle glaucoma with a visually significant cataract underwent the above mentioned procedure. An IOL was implated in the capsular bag in all cases with no intraperative complications. After surgery, all patients obtained a best corrected visual acuity of 20/20, IOL was well centered at 4 weeks follow up. The mean IOP (without any antiglaucoma medication) was 13.2 + 2.4 mm Hg at 12 weeks with a well formed diffuse filtering bleb in all the cases. CONCLUSION: The technique of combining MICS with trabeculectomy and insertion of a foldable IOL through the trabeculectomy fistula is a feasible and valuable technique for cases which require combined cataract and glaucoma surgery

Hyeropic shift after LASIK induced Diffuse lamellar keratitis

BACKGROUND: Diffuse lamellar keratitis (DLK) is a relatively new syndrome that is increasingly being reported after LASIK. We have observed that a hyperopic shift may be associated with the occurrence of this diffuse lamellar keratitis. CASE PRESENTATION: A 26 year old man developed bilateral diffuse lamellar keratitis (DLK) following myopic LASIK. The residual refractive error was +0.5D OD and +0.25D OS at the end of the first week. The sterile infiltrates resolved over a period of 4–6 weeks on topical steroid therapy. A progressive hyperopic shift was noted in the right eye with an error +4.25Dsph/+0.25Dcyl 20 at the final follow up 6 months post surgery. CONCLUSION: Diffuse lamellar keratitis after LASIK may be associated with a significant hyperopic shift

Management of glaucoma in pregnancy: risks or choices, a dilemma?

The treatment of glaucoma in and around pregnancy offers the unique challenge of balancing the risk of vision loss to the mother as against the potential harm to the fetus or newborn. Most anti-glaucoma drugs (i.e. beta-blockers, prostaglandin analogues, carbonic anhydrase inhibitors topical and systemic, cholinergics, anticholinesterases, and apraclonidine) are considered category C agents and ophthalmologists are usually limited to treating patients with the category B drugs of brimonidine and dipivefrin. Brimonidine is generally the preferred first-line drug in the first, second and early third trimester. Late in the third trimester, brimonidine should be discontinued because it can induce central nervous system depression in newborns wherein topical carbonic anhydrase inhibitors may be the optimal choice. Glaucoma surgery can be performed with caution in second and third trimester if the patients have a strong indication for the procedure. However, anesthetics, sedative agents, and antimetabolites still have potential risk for the fetus. Argon laser trabeculoplasty (ALT) or selective laser trabeculoplasty (SLT) is an alternative treatment that can be performed in all trimesters. Carbonic anhydrase inhibitors and β-blockers are certified by the American Academy of Pediatrics for use during nursing. However, low doses of these medications should be considered when used in the breast feeding period. Optimum treatment for glaucoma in pregnancy must not be withheld so as to prevent any further deterioration in progressive vision loss and quality of life

Visual outcome after intravenous dexamethasone therapy for idiopathic optic neuritis in an Indian population: A clinical case series

Purpose: To evaluate the clinical profile, response to dexamethasone treatment and visual function outcome in Indian patients with acute optic neuritis. Materials and Methods: We conducted an observational study of patients with acute optic neuritis who were treated with intravenous dexamethasone (100 mg in 250 ml of 5% dextrose over 1-2 hours daily, for three consecutive days) and had completed at least two years of follow-up. Parameters assessed included visual acuity, contrast sensitivity, color vision, visual fields, relative afferent pupillary defect (RAPD) and visually evoked potentials. Out of 40 patients studied, 26 patients (33 eyes) had all visual function parameters assessed. Twenty three patients (28 eyes) had completed two years of follow-up and were included for statistical analysis. Results: Improvement in visual acuity was statistically significant for distance after 24 hours of the first dose ( P = < 0.001) and for near vision after 24 hours of the second dose ( P = 0.006); improvement in color and contrast sensitivity was statistically significant 24 hours after the third dose ( P = < 0.001 for color vision and P = 0.013 for contrast sensitivity). Significant improvement in RAPD and visual fields were seen by 1 month ( P = 0.005). Recurrence was seen in 4 eyes of 4 patients. No serious side effects were observed. At two years, 82.14% (23 out of 28) eyes had visual acuity > 20/40. Conclusion: Treatment with intravenous pulsed dexamethasone led to rapid recovery of vision in acute optic neuritis, without any serious side effects