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P Hossain

Publications and source records attributed to P Hossain.

6 recordsLinked to original sources
PubMed2003

Assessing the 'cyclodiode G-probe' using a grey scale test: reproducibility and differences between probes.

AIMS: 1. To determine the number of clinicians performing cyclodiode therapy who reuse the 'G-probe' used for the delivery of cyclodiode therapy. 2. To show a simple method to assess the output of the 'G-probe' that can be used in the clinical setting. METHODS: A total of 71 questionnaires were sent to ophthalmologists who have an Oculight SLx Iris Medical Diode Laser. Ophthalmologists were asked as to whether they performed cycloablative therapy using the 'G-probe' and whether they reused the G-probe. They were also asked as to the frequency of any reuse of probes. To determine the output of the 'G-probe', paper copies of a custom-made grey scale chart containing graded blocks of increasing shades of grey densities were produced. A special probe holder was made so that the G-probe tip could be held at a fixed distance from the grey scale chart. Laser burns were made on the grey scale using this arrangement and measurements of the burn size were made. After using 'standard settings' of 2000 ms and 2000 mW, 'threshold' burns were defined. Five new probes (with two different operators) were tested to assess the interprobe, interoperator, and intersheet variability of test. Probes were then tested for the burn size produced between 1000 and 3000 mW, and 1000 and 3000 ms. RESULTS: Results from the questionnaire showed that of the 44 respondents (62.0% response), 93.2% performed cyclodiode therapy with 58.5% reusing the G-probe. Among them, 56.1% reused probes on more than one occasion. Results from testing a new G-probe on the grey scale chart showed that with 'standard settings', highly reproducible burns at grey density 8 could be produced. No significant interprobe, interoperator, and intersheet variations were noted. Above 3 J of laser energy, the test could detect a 20% increase in energy settings and it was found that at levels of 4 J or above, alterations to the power setting had a greater influence on burn production than alterations to the time setting. CONCLUSIONS: This study demonstrates 1. that many clinicians in the UK reuse G-probes, 2. a simple, quick, and highly reproducible method to assess the laser output from the G-probe used for cyclodiode therapy. The method can help the ophthalmic surgeon to test the G-probe prior to commencement of therapy and with a standard treatment protocol, may produce a more predictable intraocular pressure reduction.

Ciliary Body↗
PubMed2000

Fine needle diathermy occlusion of corneal vessels.

PURPOSE: To develop a novel technique, fine needle diathermy (FND), for the occlusion of corneal vessels and to evaluate its safety and efficacy in a series of patients. METHODS: Fourteen patients were treated with FND to occlude corneal vessels. Patients were categorized into four groups: group 1 (n = 4), high risk patients with stromal vascularization before keratoplasty; group 2 (n = 2), patients with progressive lipid keratopathy; group 3 (n = 4), post keratoplasty patients with active rejection episodes associated with vessels; and group 4 (n = 4), patients with disciform vascularized scars with recurrent inflammation. The success of the treatment in terms of vessel occlusion and the clinical outcome were monitored. RESULTS: All patients in group 1 had successful corneal transplantation, and the grafts remained clear without graft rejection. Patients in group 2 with lipid keratopathy had 100% obliteration of vessels with stabilization of corneal scar. All four patients in group 3 had complete regression of vessels with reversal of graft rejection. Patients with vascularized disciform scar had resolution of the inflammation without recurrence. Average follow-up was 10.3 months (minimum, 6 months; maximum, 24 months). No serious complications were observed with FND. CONCLUSIONS: FND is a useful and inexpensive technique that can serve as an adjunct or alternative to laser occlusion for the treatment of established corneal vessels. It is fairly safe and effective, although complications such as intrastromal bleeding and crystalline deposits can occur and at times it may have to be repeated once or twice to achieve the desired result.

Adult↗
PubMed1998

In vivo cell tracking by scanning laser ophthalmoscopy: quantification of leukocyte kinetics.

PURPOSE: To image peripheral blood leukocyte traffic in the normal retinal and choroidal vasculature and to quantify the differences in the circulation dynamics between normal and concanavalin A (ConA)-activated leukocytes. METHODS: Normal or ConA-activated splenocytes were fluorescently labeled in vitro with 6-carboxyfluorescein diacetate (CFDA) and reinfused in vivo where they were tracked in the retinal and choroidal circulations of syngeneic rats by means of a scanning laser ophthalmoscope (SLO). Simultaneous digital and video images were captured for as long as 30 minutes, and the initial 15 seconds of image sequences and leukocyte dynamics were analyzed from digitized images by recording the velocity of trafficking cells and the number of stationary cells that accumulated with time, using a customized software package. RESULTS: Mean velocity (+/-SD) was 29.8 +/- 15.3 mm/sec in the retinal arteries, 14.7 +/- 7.2 mm/sec in the retinal veins, and 3.0 +/- 3.6 mm/sec in the retinal capillaries. Mean velocity in the choroidal vessels was 6.1 +/- 6.0 mm/sec. No significant difference in leukocyte velocity was found between activated and normal leukocytes in any of the vessel systems. However, activated leukocytes were observed to accumulate more within the choroidal vasculature (P < 0.001) and the retinal capillaries (P < 0.001) than in control animals, but not in larger retinal vessels. CONCLUSIONS: A technique to measure the kinetics of circulating leukocytes in vivo has been developed. Although leukocyte activation itself is insufficient to cause slowing of leukocyte velocity, the data indicate that leukocyte adherence to endothelium can be induced in the absence of local or systemic activating stimuli.

Animals↗
PubMed1991

Structure-function studies of S-antigen: use of proteases to reveal a dominant uveitogenic site.

Retinal S-antigen induced experimental autoimmune uveitis (EAU) is a severe, predominantly T-cell mediated inflammatory disease of the uveal tract and retina of the eye. Pretreatment of LEW rats with the monoclonal antibody, MAbS2.4.C5, which defines an epitope in S-antigen, has been shown to effectively inhibit the subsequent induction of EAU with S-antigen. Using synthetic peptides and cyanogen bromide fragments of S-antigen we found the binding site of MAbS2.4.C5 to be located at the carboxy terminus of the molecule corresponding to amino acid positions 375 to 380. Limited Staphylococcus aureus V8 protease digestion yielded several polypeptide fragments including one large 43 kD fragment which retained antibody binding to a variety of both polyclonal and monoclonal antibodies which identify epitopes that span the length of the S-antigen. This treatment, however, completely destroys the MAbS2.4.C5 binding site and dramatically reduces uveitopathogenicity. Limited trypsin and papain digestion, on the other hand, had little effect on pathogenicity or on MAbS2.4.C5 binding to S-antigen or its peptide fragments. These results indicate that the carboxy-terminus of S-antigen plays a predominant role in the pathogenesis of EAU.

Amino Acid Sequence↗