Biomedical subjects

R H Trivedi

Publications and source records attributed to R H Trivedi.

14 recordsLinked to original sources

PubMed2002

Post cataract-intraocular lens (IOL) surgery opacification.

Intraocular lens (IOL) implantation has no doubt been one of the most satisfying advances of medicine. Millions of individuals with visual disability or frank blindness from cataracts had and continue to have benefit from this procedure. It has been reported by ophthalmologists that the modern cataract-intraocular lens (IOL) surgery is safe and complication-free most of the time. This makes the watchword for any cataract surgeon to be 'implantation,' 'implantation,' 'implantation.' In the mid-1980s, as IOLs were evolving rapidly, the watchword of the implant surgeon was 'fixation,' 'fixation,' 'fixation.' Most techniques, lenses and surgical adjuncts now allow us to achieve the basic requirement for successful IOL implantation, namely long-term stable IOL fixation in the capsular bag. However despite this advancement some items 'slipped through cracks.' In this article, we would like to alert the reader to a new watchword, namely 'opacification,' 'opacification,' 'opacification.' Here we will be talking about the good, the bad, and the ugly. Examples of the 'good' include the recent successes now being achieved in reducing the incidence of posterior capsule opacification. Examples of the 'bad' include various proliferations of anterior capsule cells, problems caused by silicone oil adherence to IOLs and problems with piggyback IOLs. The 'ugly' include the sometimes striking and often visually disabling opacifications occurring on and within IOL optics, both on some modern foldable IOLs as well as a poly(methyl methacrylate) (PMMA) optic degradation occurring with some models a decade or more after implantation.

Cataract↗

PubMed2001

The effect of ship scrapping industry and its associated wastes on the biomass production and biodiversity of biota in in situ condition at Alang.

The main pollutants for the ship scrapping industry and its associated wastes at Alang are heavy metals, petroleum hydrocarbon and bacterial contaminations. The concentration of iron, manganese, cobalt, copper, zinc, lead, cadmium, nickel and mercury were 25 to 15,500% more at nearshore station of Alang as compared to control site at Piram. The concentration of heavy metals in the nearshore station of Alang was always higher than its concentration at 10 km away. The concentration of petroleum hydrocarbon was 16,973 and 53,900% more at the nearshore and 10 km away respectively at Alang as compared to controls. The concentration of chlorophyll-a and phaeophytin were in non-detectable range (< 0.2 and < 0.1 mg m3) or much lower concentration at both the stations of Alang as compared to controls. The total viable count, total coliform, Escherichia coli, Vibrio cholerae, Vibrio parahaemolyticus and other Vibrio, Streptococcus faecalis, Shigella, Salmonella, Proteus, and Klebsiella were always higher (17%-605%) at the nearshore station of Alang as compared to control. Similar trend was observed at 10 km away from Alang. Bacteria in sediment also showed the same pattern of variation. Phytoplankton counts at the nearshore station and 10 km away from Alang were only slightly raised. In contrast to phytoplankton, the zooplankton showed considerable reduction of growth (-10 to -66%) at Alang.

Bacteria↗

PubMed2001

Necessity of vitrectomy when optic capture is performed in children older than 5 years.

PURPOSE: To determine whether anterior vitrectomy is necessary when optic capture is performed in children between 5 and 12 years old with congenital cataract. SETTING: Iladevi Cataract and IOL Research Center, Ahmedabad, India. METHODS: This prospective randomized controlled study comprised 41 eyes of 25 children whose mean age was 83.57 months (range 60 to 144 months). Intraocular lens (IOL) implantation with optic capture through a primary posterior continuous curvilinear capsulorhexis was performed in all the eyes. The IOL haptics were bag fixated. Patients were randomly assigned to 1 of 2 groups. Vitrectomy was performed in 1 group (n = 21 eyes) and not performed in the other group (n = 20 eyes). The mean follow-up was 21.04 months. A Student t test and chi-square test were used for statistical analysis. RESULTS: All eyes in the vitrectomy group and 30% in the no-vitrectomy group had a clear visual axis at the last follow-up (P <.001) The visual axis was obscured as a result of anterior vitreous fibrosis in 70% of eyes in the no-vitrectomy group. High-contrast visual acuity was not significantly different between groups (P =.28). Low-contrast sensitivity was significantly better in the vitrectomy group (P =.02). Eighteen eyes (85.7%) in the vitrectomy group and 16 eyes (80%) in the no-vitrectomy group developed deposits on the IOL (P =.62). The deposits were present at the last follow-up in 4 eyes (19.0%) in the vitrectomy group and in 6 eyes (30.0%) in the no-vitrectomy group (P =.85). Three eyes (14.3%) in the vitrectomy group and 8 eyes (40.0%) in the no-vitrectomy group developed synechias (P =.06). CONCLUSION: The results suggest that anterior vitrectomy is necessary with optic capture in children with congenital cataract who are between 5 and 12 years old.

Capsulorhexis↗

PubMed2001

[Postoperative opacification of posterior chamber intraocular lenses - a review].

Postoperative opacification of intraocular lenses (IOLs) is a very unpleasant complication for the ophthalmic surgeon and the patient. We report on our experiences with opacification of different foldable IOL designs and rigid poly (methyl methacrylate) (PMMA) posterior chamber lenses.1. Snowflake degeneration of PMMA IOLs: This condition is an unanticipated and surprising late postoperative finding 8 to 15 years after implantation. In our opinion, this complication is probably not related to the PMMA biomaterial itself, but rather it appears to represent a manufacturing problem that has affected a selected, albeit large number of lenses manufactured in the 1980s-mid 1990s.2. Degeneration of UV absorber material and calcium deposits within the optic of hydrophilic IOLs: Two years postoperatively degenerations of UV absorber material and calcium deposits within the optic of single piece hydrophilic acrylic lenses SC60B-OUV manufactured by MDR (Medical developmental research Inc. Clearwater FL, USA) can occur. Although the precise mechanism is not fully known, it was assumed that these opacifications are due to premature aging of the UV blocking agent incorporated in the lens biomaterial and calcification.3. Calcification on the surface of the Bausch & Lomb Hydroviewtrade mark IOLs: Twelve to 15 months postoperatively granular surface calcifications in Hydroviewtrade mark IOLs occured. The mechanism is not fully understood. According to Bausch and Lomb studies, part of the components of the packaging contained silicone, which may have come off the packaging onto the lens optic, where it then appears to be a catalyst for calcium precipitation. The manufacturer has correlated a change in packaging with the appearance of the opacification. The manufacturer now believes that this problem has been solved. However, final verification will require a careful 1 - 2 years clinical study.4. Glistenings in the hydrophobic acrylic AcrySoftrade mark IOLs: The time frame of glistenings in the AcrySoftrade mark IOLs is highly variable. It has been suggested that the occurrence of glistenings may be related to variations in the temperature of the lens just prior to and or during insertion into the eye. Formation of vacuoles may occur within the submersed acrylic polymer when there is a transient increase and then decrease in temperature during the surgical procedure. "Glistenings" may then subsequently form by ingress of anterior chamber fluid. Contrast sensitivity can been decreased in some patients, but clinically significant decrease of visual acuity has been rare.

Biocompatible Materials↗

PubMed2001