Effect of vadose zone on the steady-state leakage rates from landfill barrier systems.

Leakage rates are evaluated for a landfill barrier system having a compacted clay liner (CCL) underlain by a vadose zone of variable thickness. A numerical unsaturated flow model SEEP/W is used to simulate the moisture flow regime and steady-state leakage rates for the cases of unsaturated zones with different soil types and thicknesses. The results of the simulations demonstrate that harmonic mean hydraulic conductivity of coarse textured vadose zones is 3-4 orders of magnitude less than saturated hydraulic conductivity; whereas, the difference is only one order of magnitude for fine textured vadose zones. For both coarse and fine textured vadose zones, the effective hydraulic conductivity of the barrier system and the leakage rate to an underlying aquifer increases with increasing thickness of the vadose zone and ultimately reaches an asymptotic value for a coarse textured vadose zone thickness of about 10m and a fine textured vadose zone thickness of about 5m. Therefore, the fine and coarse textured vadose zones thicker than about 5m and 10m, respectively, act as an effective part of the barrier systems examined. Although the thickness of vadose zone affects the effective hydraulic conductivity of the overall barrier system, the results demonstrated that the hydraulic conductivity of the CCL is the dominant factor controlling the steady-state leakage rates through barrier systems having single low permeability clay layers.

Loxosceles reclusa bite to the eyelid.

PURPOSE: The authors report a case of Loxosceles reclusa infestation on the eyelid. METHODS: The specimen collected by swabbing the lesions with gauze was tested by using a venom-specific enzyme-linked immunosorbent assay. Loxosceles venom was detected in specimen. The patient was managed with conservative therapy that included saline compresses and ocular lubrication. RESULTS: The case presented with severe edema and necrosis on the left upper eyelid. On laboratory examination, a significant left shift of white blood cell count was detected. Although residual scar of the eyelid and punctate epitheliopathy on the inferior of cornea was detected, vision was not impaired. CONCLUSIONS: Supportive therapy may be reasonable treatment for Loxosceles reclusa infestation on the eyelids. The presence of venom proteins detected with an enzyme-linked immunosorbent assay technique is beneficial for supporting the diagnosis of Loxosceles envenomatio.

Unilateral vernal keratoconjunctivitis: a case report.

PURPOSE: A rare case of unilateral vernal keratoconjunctivitis is presented. METHODS: A 5-year-old boy had itching, foreign body sensation, redness, and ptosis in his left eye. Impression cytology specimens were taken from both upper eyelid tarsal conjunctiva. RESULTS: On slit-lamp biomicroscopy, unilateral cobblestone papillae and a shield ulcer were found in the left eye. On impression cytology examination, there was a significant increase in inflammation, presence of a honeycomb pattern, plasma cells, and mucus strands in the upper tarsal conjunctiva of the specimens. CONCLUSIONS: Giant papillary conjunctivitis must be considered in differential diagnosis of unilateral vernal conjunctivitis. Impression cytology method may be combined with the clinical findings in vernal keratoconjunctivitis diagnosis.

Conjunctival deposits as the first sign of systemic sarcoidosis in a pediatric patient.

PURPOSE: Sarcoidosis is an inflammatory disease of unknown cause, characterized by noncaseating granulomas. In this study, the authors present a sarcoidosis patient without systemic signs diagnosed by histopathologic analysis of conjunctival deposits. METHODS: A 10-year-old girl had bilateral, focal, multilobular, multiple pale yellow deposits in bulbar conjunctiva for a year. In the patient's biomicroscopic examination, numerous 0.50- to 2-mm diameter pale yellow deposits were determined in both bulbar conjunctivas. The patient had no other systemic or ocular complaints. A conjunctival biopsy was performed. RESULTS: The biopsy specimens showed noncaseating granulomas with prominent asteroid bodies. Serum angiotensin-converting enzyme levels were increased in the patient. Conjunctival deposits were the first manifestation of sarcoidosis in the patient and the diagnosis of sarcoidosis was confirmed with a conjunctival biopsy. CONCLUSIONS: To the authors' knowledge, this is the second study that reports a sarcoidosis patient with non-systemic involvement diagnosed after histopathologic analysis of conjunctival deposits.

Conjunctival deposits as the first sign of systemic sarcoidosis in a pediatric patient.

PURPOSE: Sarcoidosis is an inflammatory disease of unknown cause, characterized by noncaseating granulomas. In this study, the authors present a sarcoidosis patient without systemic signs diagnosed by histopathologic analysis of conjunctival deposits. METHODS: A 10-year-old girl had bilateral, focal, multilobular, multiple pale yellow deposits in bulbar conjunctiva for a year. In the patient's biomicroscopic examination, numerous 0.50- to 2-mm diameter pale yellow deposits were determined in both bulbar conjunctivas. The patient had no other systemic or ocular complaints. A conjunctival biopsy was performed. RESULTS: The biopsy specimens showed noncaseating granulomas with prominent asteroid bodies. Serum angiotensin-converting enzyme levels were increased in the patient. Conjunctival deposits were the first manifestation of sarcoidosis in the patient and the diagnosis of sarcoidosis was confirmed with a conjunctival biopsy. CONCLUSIONS: To the authors' knowledge, this is the second study that reports a sarcoidosis patient with non-systemic involvement diagnosed after histopathologic analysis of conjunctival deposits. (Eur J Ophthalmol 2006; 16: 168-70).

Spontaneous fracture of an implanted posterior chamber intraocular lens.

PURPOSE: Spontaneous fracture of an intraocular lens (IOL) haptic is a rare complication of cataract surgery. The authors report a case of spontaneous fracture of an implanted posterior chamber IOL. CASE: Five years ago, a 12-year-old patient underwent linear lens extraction, posterior capsulotomy, and anterior vitrectomy due to traumatic cataract and received a polymethyl methacrylate (PMMA) biconvex posterior chamber IOL implanted in ciliary sulcus. Five years later, IOL optic was found in anterior chamber with its haptics broken from the optic-haptic junction. DISCUSSION: The broken haptic was examined with scanning electron microscopy. The fracture site of the haptic was on the optic-haptic junction. The fractured surface had a regular appearance. CONCLUSIONS: To our knowledge, this is the fourth report of spontaneous fracture of an implanted posterior chamber IOL.

Spontaneous fracture of an implanted posterior chamber intraocular lens.

PURPOSE: Spontaneous fracture of an intraocular lens (IOL) haptic is a rare complication of cataract surgery. The authors report a case of spontaneous fracture of an implanted posterior chamber IOL. CASE: Five years ago, a 12-year-old patient underwent linear lens extraction, posterior capsulotomy, and anterior vitrectomy due to traumatic cataract and received a polymethyl methacrylate (PMMA) biconvex posterior chamber IOL implanted in ciliary sulcus. Five years later, IOL optic was found in anterior chamber with its haptics broken from the optic-haptic junction. DISCUSSION: The broken haptic was examined with scanning electron microscopy. The fracture site of the haptic was on the optic-haptic junction. The fractured surface had a regular appearance. CONCLUSIONS: To our knowledge, this is the fourth report of spontaneous fracture of an implanted posterior chamber IOL.

Treatability of chromite ore processing waste by leaching.

Developing treatment and disposal strategies and health-based clean-up standards for chromium containing wastes continues to be an important environmental regulatory issue because of the opposing solubility and toxicity characteristics of chromium species under diverse environmental conditions. In this study, leaching characteristics of total Cr and Cr(VI) were investigated using laboratory column studies. The data obtained from the experimental studies were analysed to assess the treatability of chromite ore processing waste (COPW) by leaching and to identify the leaching strategies that enhance mass removal rates of chromium species. COPW used for laboratory soil column studies was obtained from an industrial plant producing sodium chromate in Mersin, Turkey. Laboratory investigations involved chemical characterisation of waste material and column studies. For waste characterisation, U.S. EPA toxicity characterisation leaching procedure (TCLP) was performed on COPW to determine the concentrations of metal species in the TCLP extract. For column studies, various laboratory columns containing plain COPW material, 1:1 COPW/reducing agent (elemental iron or manure) mixture and different type soils (sand, loam and clay) overlain by COPW were subjected to leaching tests using acidic, neutral and alkaline influent water to determine Cr mass leaching efficiencies. Based on the TCLP analyses, COPW is classified as hazardous waste. As a result of comparing the leaching efficiency data from twelve leaching columns, the maximum removal of total Cr was achieved by leaching COPW/manure mixture using acidic (pH 4.78) influent water. The highest Cr(VI) leaching efficiency was achieved in the columns of plain COPW and COPW/manure mixture using highly alkaline (pH 12.0) influent water. The least effective leaching efficiency for both total Cr and Cr (VI) was obtained by leaching plain COPW with neutral (pH 7.0) influent water. Land-disposal of the treated COPW material by mixing with clayey soils seems to be a viable alternative.

A model for optimal operation of land-treatment sites for oily wastes.

Land treatment as a disposal technology has been extensively used for the disposal of oily wastes. Effective management of land treatment sites require optimal operation of the system in order to achieve the fastest and most complete degradation of petroleum hydrocarbons without contamination of the environment. This paper describes a model that can be used for optimising the operation of land treatment sites for oily wastes. The model is composed of system simulator and optimisation submodels. Conceptually, the system simulation submodel is composed of a waste mixing zone, lower treatment zone and aquifer modules. The system simulation model allows for periodic waste applications and determines the spatial and temporal variation of the state variables such as phase summed (total) and aqueous phase contaminant concentrations and water content in the system. The optimisation submodel coupled with the system simulator determines the optimal values of system control variables, such as waste loading rate, infiltration rate, water content, frequency of waste application and the dimensions of the land treatment site. Optimisation of these system control variables is accomplished by maximising the hydrocarbon mass removal from the waste mixing zone under the constraint of satisfying a prespecified water quality criteria in the aquifer. Selected model applications are presented to demonstrate the applicability and utility of the model. Such model applications include determination of the optimal operating conditions for the land treatment of oily wastes under various different site and soil environmental conditions and practical waste disposal scenarios.

Descemet membrane detachment after viscocanalostomy.

PURPOSE: To report a case that developed a large Descemet membrane detachment after viscocanalostomy. METHODS: Case report. A 60-year-old man with primary open-angle glaucoma underwent viscocanalostomy RE. One day after surgery, a small, localized detachment of Descemet membrane was present at the operation site. Six months after surgery, he had a large superior Descemet membrane detachment involving his visual axis. RESULTS: The Descemet membrane remained attached after descemetopexy with sodium hyaluronate and air. Final visual acuity was 20/80, and intraocular pressure was 17 mm Hg without medication. CONCLUSION: Detachment of the Descemet membrane should be recognized as a potential complication of viscocanalostomy.

Prospective evaluation of the argon laser treatment of trachomatous trichiasis.

PURPOSE: To evaluate the effectiveness of argon laser photocoagulation for the treatment of trachomatous trichiasis. METHODS: This report presents a prospective, non-masked study of 22 patients (36 eyelids) with trachomatous trichiasis treated with the argon laser. Each abnormal lash was treated with a beam of 50- to 200-micron spot size, for 0.2 seconds, and 1 to 1.2 watts power. In 30 lids (83.3%) infiltration anesthesia was used and in 6 lids (16.7%) no anesthesia was used. RESULTS: Successful treatment with no evidence of recurrence was achieved in 55.5% of lids after one laser session. The remaining 44.5% of the lids required two or three sessions. The final success rate of the method was 88.9%. No complications were observed. The mean follow-up time was 10.6 months. CONCLUSION: Argon laser photocoagulation is an effective and safe method for the treatment of trachomatous trichiasis.

Mitomycin C primary trabeculectomy with releasable sutures in primary glaucoma.

PURPOSE: To evaluate the effects of mitomycin C and a releasable suture technique on outcomes of primary trabeculectomy in primary glaucoma patients. METHODS: A prospective analysis of patients who underwent primary trabeculectomy with a mitomycin C concentration of 0.2 mg/mL for 2 minutes. For closing the scleral flap, releasable sutures were used in 18 patients (17 eyes), Group 1, or permanent sutures in 18 patients (20 eyes), Group 2. Clinical outcome factors including postoperative intraocular pressure (IOP), visual acuity, and incidence of complications were determined. RESULTS: The mean follow-up periods were 8.1 +/- 1.3 months in Group 1 and 8.3 +/- 1.3 months in Group 2. The postoperative reduction in IOP was highly significant (P <.0001) at all time intervals in both groups. In all measurement of IOP before the second week, mean IOP in Group 2 was found significantly lower than the mean IOP in Group 1 (P =.01). No statistically significant differences were found between the groups at later mean IOP measurements. At the last visit, the complete success rate was 88.8% in Group 1 and 85.0% in Group 2. No serious complications such as hypotonous maculopathy were observed in any patient. CONCLUSION: Primary trabeculectomy with mitomycin C in eyes with primary glaucoma showed effective IOP pressure reduction. There were no cases of serious complications. In the early postoperative period IOP was controlled better in the releasable suture group.

Gentian violet solution for staining the anterior capsule.

PURPOSE: To evaluate the histopathological changes after injecting gentian violet solution into the anterior chamber of rats and to describe a technique that uses gentian violet to allow a clear view of the anterior capsule during continuous curvilinear capsulorhexis (CCC) in human eyes with white mature cataract. SETTING: Department of Ophthalmology, University of Dicle, Diyarbakir, Turkey. METHODS: In this masked, experimental study (first stage), 0.05 mL of gentian violet 0.01% or 0.001% solution or balanced salt solution (BSS) (control group) was injected into the anterior chamber of 30 eyes of 30 Wistar albino rats. One, 24, and 48 hours after injection, 4 eyes in each group and 2 eyes in the control group were enucleated, and histopathological examination was performed. In the second stage, these solutions were used for staining the anterior capsule in the 18 human eyes with white mature cataract. The success rate of CCC and intraoperative and postoperative complications were evaluated. RESULTS: Histopathological examination revealed no pathology in any group. A CCC was completed in all cases. No intraoperative or postoperative complications were observed in human eyes except mild corneal edema and mild inflammatory reaction in the anterior chamber that improved within 1 week. Mean follow-up was 3.4 months. Visualization of the anterior capsule was better with gentian violet 0.01% solution. CONCLUSIONS: Gentian violet solutions at 0.01% and 0.001% concentrations had no evident toxic effect that caused significant histopathological changes. The staining technique was practical and helped the surgeon visualize the anterior capsule. However, gentian violet may have adverse effects that lead to corneal edema.

Impression cytology, tear film break up, and Schirmer test in patients with inactive trachoma.

Schirmer I and tear film break up time (BUT) test were used to determine cytological changes and conjunctival surface epithelial morphology was investigated using impression cytology in patients with inactive trachoma; patients with mild and severe scarring, and control subjects, were compared. Schirmer I, BUT, and goblet cell populations were significantly lower whereas the grade of squamous metaplasia was significantly higher in patients with inactive trachoma. There was a close correlation between our findings and the clinical severity of trachoma.