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Biomedical subjects

A R Vasavada

Publications and source records attributed to A R Vasavada.

At least 19 recordsLinked to original sources
PubMed2001

Acute transient bilateral diabetic posterior subcapsular cataracts(1).

A 62-year-old man in whom diabetes was recently detected presented with visually significant, bilateral posterior subcapsular cataracts within days of initiating antihyperglycemic therapy. With efficient control and a stable serum glucose level, the cataracts started regressing. Except for a few scattered opacities, the patient was left with essentially clear lenses. Visual acuity of counting fingers at 2 ft in the right eye and 20/63 in the left eye improved to 20/20 in both eyes within 5 weeks.

Acute Disease↗
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

Phacoemulsification of brunescent and black cataracts.

PURPOSE: To evaluate the efficacy and safety of a step-by-step, chop in situ, lateral separation technique to remove brunescent and black cataracts. SETTING: Iladevi Cataract and IOL Research Center, Ahmedabad, India. METHODS: In this prospective study conducted between May 1997 and June 1998, 167 consecutive eyes were divided into 2 groups: Group 1, brunescent cataract (n = 123), and Group 2, black cataract (n = 44). Preoperative assessment included axial length (AL), slitlamp examination, corneal pachymetry, tonometry, and specular microscopy. During phacoemulsification performed by a single surgeon, a step-by-step, chop in situ, lateral separation technique was used to divide the nucleus. Intraoperatively, hydroxypropyl methylcellulose 2% was used and irrigation was by balanced salt solution (BSS). Postoperatively, all eyes were assessed at 1, 7, 30, 90, 180, and 360 days. The results were evaluated using regression analysis, the chi-square test, and the Student t test. RESULTS: The mean follow-up was 14.4 months (range 6 to 35 months) in Group 1 and 13.0 months (range 6 to 32 months) in Group 2. The AL was significantly greater in Group 2 (P =.02). Corticapsular adhesions were present in 17.82% in Group 1 and 31.82% in Group 2. The mean cumulative dissipated energy was 2.03 and 3.12, respectively (P =.0005). Wound site thermal injury occurred in 16 eyes (13.01%) in Group 1 and 4 eyes (9.09%) in Group 2. No serious intraoperative or postoperative complications were noted. One day postoperatively, the mean rise in intraocular pressure was 1.76 mm Hg in Group 1 and 4.15 mm Hg in Group 2 (P =.012), and transient corneal edema was present in 24.40% and 34.10%, respectively. At 1 month, the endothelial cell loss was 10.06% in Group 1 and 9.22% in Group 2. CONCLUSION: The step-by-step, chop in situ, lateral separation technique was effective and did not produce serious complications such as zonulysis or posterior capsule rupture. However, the incidence of wound site thermal injury and endothelial cell loss was greater than after emulsification of standard cataracts.

Acetates↗
PubMed2000

Proximate humid and dry regions in Jupiter's atmosphere indicate complex local meteorology.

Models of Jupiter's formation and structure predict that its atmosphere is enriched in oxygen, relative to the Sun, and that consequently water clouds should be present globally near the 5-bar pressure level. Past attempts to confirm these predictions have led to contradictory results; in particular, the Galileo probe revealed a very dry atmosphere at the entry site, with no significant clouds at depths exceeding the 2-bar level. Although the entry site was known to be relatively cloud-free, the contrast between the observed local dryness and the expected global wetness was surprising. Here we analyse near-infrared (around 5 microm) observations of Jupiter, a spectral region that can reveal the water vapour abundance and vertical cloud structure in the troposphere. We find that humid and extremely dry regions exist in close proximity, and that some humid regions are spatially correlated with bright convective clouds extending from the deep water clouds to the visible atmosphere.

Atmosphere↗
PubMed2000

Induction of cataracts of varying degrees of hardness in human eyes obtained postmortem for cataract surgeon training.

PURPOSE: To report a method of inducing nuclear cataracts of varying degree of hardness using intralenticular injection of the Karnovsky solution. METHODS: Twelve postmortem human eyes were prepared according to the Miyake-Apple posterior video technique. After performing capsulorhexis and hydrodissection/delineation, 0.2 ml of the Karnovsky solution was injected into the lens nucleus of the eyes. Manual extracapular cataract extraction techniques and various two-handed phacoemulsification maneuvers were then practiced at various time intervals after the injection. RESULTS: Uniform nuclear cataracts with varying degrees of hardness were successfully induced in all globes. The optimum dose of the Karnovsky solution and time for induction of nuclear hardness of grade 3 (ideal for practicing two-handed phacoemulsification maneuvers) were 0.2 ml and 15 minutes, respectively. CONCLUSION: The Karnovsky solution can be successfully used for the induction of hard, uniform nuclear cataracts for learning/practicing extracapular cataract extraction and phacoemulsification.

Cataract↗
PubMed2000

Role of optic capture in congenital cataract and intraocular lens surgery in children.

PURPOSE: To evaluate the role of optic capture in eyes having cataract extraction, anterior vitrectomy, and intraocular lens (IOL) implantation for congenital cataract. SETTING: Iladevi Cataract & IOL Research Centre, Ahmedabad, India. METHODS: This prospective study comprised 40 eyes of 28 children, whose mean age was 26.08 months (range 4 to 55 months). Primary posterior continuous curvilinear capsulorhexis, anterior vitrectomy, and IOL implantation were performed in all eyes. Eyes were randomly assigned to 1 of 2 groups of 20 each: in 1 group, optic capture would be used and in the other, the noncapture technique. Permanent optic capture was achieved in 14 eyes, and 26 eyes had no optic capture. Mean follow-up was 16.53 months (range 5 to 24 months). A Student t test and chi-square test were used for statistical analyses. RESULTS: All eyes in both groups maintained a clear visual axis. One eye in the optic-capture group developed a membrane in front of the IOL that required a secondary procedure. Posterior synechia formation was significantly greater in the optic-capture group (P =.04), as were deposits on the IOL optic (P =.0086). Although all eyes in both groups maintained a clinically centered IOL, geometric decentration was more common in the no-capture group (P =.0000). CONCLUSION: Optic capture resulted in better IOL centration but predisposed the eye to an increased uveal inflammatory response.

Biocompatible Materials↗
PubMed2000

Is pseudophakic astigmatism a desirable goal?

PURPOSE: To determine whether pseudophakic astigmatism is a desirable goal, and if so, which one is better: against-the-rule (ATR) or with-the-rule (WTR). METHOD: Eyes were included only if they had an uncorrected vision > or = 6/18 and N/18. Three groups, of 40 patients each were evaluated: group 1, pseudophakes with neutral astigmatism; group 2, with ATR and group 3, with WTR astigmatism Unaided distance and near visual acuity was recorded. Statistical analysis was performed using the chi-square test for independence. RESULTS: Unaided distance vision of > or = 6/7.5 was achieved in 19 eyes (47.5%) of group 1 (neutral), 12 eyes (30%) in group 2 (ATR), and 5 eyes (12.5%) in group 3 (WTR) (p = 0.0133, significant). Unaided near vision of > or = N/9 was achieved in 17 eyes (42.5%) in group 1 (neutral), 34 eyes (85%) in group 2 (ATR), and 10 eyes (25%) in group 3 (WTR) (P < 0.001, significant). Group 1 (neutral) fared the best for unaided distance visual acuity. Group 2 (ATR) was better than in group 3 (WTR) for distant vision. Group 2 (ATR) fared the best for unaided near vision. CONCLUSION: ATR astigmatism could be a desirable goal after cataract extraction in selected populations because the largest proportion of these cases achieved good unaided near vision with acceptable distant vision.

Astigmatism↗
PubMed1999

Posterior capsule striae.

PURPOSE: To find the incidence, contributing factors, outcomes, and clinical impact of intraoperative posterior capsule striae. SETTING: Iladevi Cataract & IOL Research Centre, Ahmedabad, India. METHODS: In a prospective study, 100 consecutive eyes had phacoemulsification and intraocular lens (IOL) (AcrySof MA30BA) implantation. The presence of striae was noted at the end of the operation, and factors contributing to their development were identified. Follow-up was done at regular intervals, and the clinical impact of striae on patients' vision was evaluated. RESULTS: Striae were observed in 56 eyes (Group 1) but were absent in 44 (Group 2). Mean age in Group 1 was 65.96 years +/- 9.15 (SD) and in Group 2, 59.20 +/- 10.36 years (P = .0012). Mean axial lengths were 23.47 +/- 1.63 and 24.12 +/- 1.49 mm, respectively (P = .0419). Average lens thickness was greater in Group 1 (4.50 +/- 0.43 mm) than in Group 2 (4.13 +/- 0.41 mm) (P = .0001). The sex of patient, capsulorhexis size and centration, grade of cataract hardness, scleral rigidity, and IOL centration were not found to contribute to striae development. The striae disappeared by 5 months postoperatively and did not show a positive Maddox rod phenomenon. CONCLUSION: Intraoperative striae observed in many patients were associated with relatively older age, greater lens thickness, and shorter axial length. The striae eventually disappeared and had no effect on vision.

Cataract Extraction↗
PubMed1999

Flash heating on the early Earth.

It has been suggested that very large impact events (approximately 500 km diameter impactors) sterilized the surface of the young Earth by producing enough rock vapor to boil the oceans. Here, we consider surface heating due to smaller impactors, and demonstrate that surface temperatures conductive to organic synthesis resulted. In particular, we focus on the synthesis of thermal peptides. Previously, laboratory experiments have demonstrated that dry heating a mixture of amino acids containing excess Asp, Glu, or Lys to temperatures approximately 170 degrees C for approximately 2 hours yields polypeptides. It has been argued that such temperature conditions would not have been available on the early Earth. Here we demonstrate, by analogy with the K/T impact, that the requisite temperatures are achieved on sand surfaces during the atmospheric reentry of fine ejecta particles produced by impacts of bolides approximately 10-20 km in diameter, assuming approximately 1-100 PAL CO2. Impactors of this size struck the Earth with a frequency of approximately 1 per 10(4)-10(5) y at 4.2 Ga. Smaller bolides produced negligible global surface heating, whereas bolides > 30 km in diameter yielded solid surface temperatures > 1000 K, high enough to pyrolyze amino acids and other organic compounds. Thus, peptide formation would have occurred globally for a relatively narrow range of bolide sizes.

Amino Acids↗
PubMed1998

Posterior capsular plaque: a common feature of cataract surgery in the developing world.

PURPOSE: To study the histopathologic findings of posterior capsular plaque, a lesion that is discovered frequently in eyes undergoing cataract surgery in the developing world. METHODS: Two hundred human crystalline lenses removed from 200 eyes of 200 patients who underwent intracapsular cataract extraction at Sagarmatha Choudhary Eye Hospital in Nepal were analyzed histopathologically. RESULTS: Forty-nine lenses (24.5%) had a posterior capsular plaque. We confirm that the posterior plaques are composed of collagen that stains positively for Masson trichrome stain and that forms after pseudofibrous metaplasia of lens cells along the posterior capsule. The plaques form in a fashion analogous to a healing process. CONCLUSIONS: We postulate that posterior capsular plaques result from posterior migration of epithelium and pseudofibrous metaplasia of lens epithelium. Most of the posterior capsular plaques are minute and not likely to affect vision. However, a small percentage of plaques are thicker and are likely to impair vision after extracapsular cataract surgery.

Adult↗
PubMed1998

Human lens epithelial layer in cortical cataract.

Normal and cataractous human eye lenses were studied by morphology and protein analysis. A marked decrease in protein sulfhydryl (PSH) and nonprotein sulfhydryl (NSPH) was observed in nuclear and cortical cataractous epithelia. Moreover, decrease in PSH contents and an increase in insoluble proteins were found to be correlated only in cortical cataractous epithelium which is also accompanied by various morphological abnormalities. In nuclear cataractous epithelium, however, there was very little insolubilisation of proteins. The epithelial morphology in nuclear cataracts was almost similar to normal lens epithelium. Hence, it is assumed that the protein insolubilisation and various morphological abnormalities are characteristics of cortical cataractous epithelium. This leads us to believe that opacification in cortical cataract might initiate in the epithelial layer.

Adult↗
PubMed1997

Incidence of posterior capsular plaque in cataract surgery.

OBJECTIVE: To determine the incidence of posterior capsular plaque detected during cataract surgery, its association with age and type of cataract, and its impact on vision. SETTING: Raghudeep Eye Clinic and Iladevi Cataract & IOL Research Centre, Ahmedabad, India. METHODS: This prospective study comprised 256 consecutive eyes having extracapsular cataract extraction with posterior chamber intraocular lens implantation. The presence of plaque on the posterior capsule was noted and charted. Plaque peeling or posterior capsulorhexis was not done at the time of surgery. Mean patient age was 59 years (range 24 to 83 years). Follow-up was up to 1 year. RESULTS: The overall incidence of plaque was 10.16%. The incidence by type of cataract was 5.13%, nuclear sclerotic; 12.50%, posterior subcapsular; 9.68%, mixed; 27.27%, mature (P < .05). The difference in incidence according to cataract type was highly significant between patients older than 50 years and those younger than 50 years (P < .001). At the end of 1 year, 61.54% of patients with plaque maintained a visual acuity of 20/20 to 20/30; 30.77%, 20/40; 7.69%, 20/60 or worse. CONCLUSION: The incidence of plaque was higher in eyes with mature cataract at any age and in eyes with posterior subcapsular cataract in younger patients. Its presence was compatible with reasonable vision at the end of 1 year.

Adult↗
PubMed1996

Stop, chop, chop, and stuff.

We describe a variation of stop and chop phacoemulsification. During chopping the chopper's vertical element is depressed posteriorly toward the optic nerve and is placed well within the capsulorhexis margin, leading to in situ chopping. Each fragment is continuously chopped, and the small pieces are stuffed inside the phaco probe port with the left hand. The phaco probe is used more for aspiration than for cutting. This technique is particularly useful in eyes with hard nuclei or small pupils.

Humans↗
PubMed1993

Acid phosphatase and lipid peroxidation in human cataractous lens epithelium.

The anterior lens epithelial cells undergo a variety of degenerative and proliferative changes during cataract formation. Acid phosphatase is primarily responsible for tissue regeneration and tissue repair. The lipid hydroperoxides that are obtained by lipid peroxidation of polysaturated or unsaturated fatty acids bring about deterioration of biological membranes at cellular and tissue levels. Acid phosphatase and lipid peroxidation activities were studied on the lens epithelial cells of nuclear cataract, posterior subcapsular cataract, mature cataract, and mixed cataract. Of these, mature cataractous lens epithelium showed maximum activity for acid phosphatase (516.83 moles of p-nitrophenol released/g lens epithelium) and maximum levels of lipid peroxidation (86.29 O.D./min/g lens epithelium). In contrast, mixed cataractous lens epithelium showed minimum activity of acid phosphatase (222.61 moles of p-nitrophenol released/g lens epithelium) and minimum levels of lipid peroxidation (54.23 O.D./min/g lens epithelium). From our study, we correlated the maximum activity of acid phosphatase in mature cataractous lens epithelium with the increased areas of superimposed cells associated with the formation of mature cataract. Likewise, the maximum levels of lipid peroxidation in mature cataractous lens epithelium was correlated with increased permeability of the plasma membrane. Conversely, the minimum levels of lipid peroxidation in mixed cataractous lens epithelium makes us presume that factors other than lipid peroxidation may also account for the formation of mixed type of cataract.

Acid Phosphatase↗