A clear understanding of the physical and mechanical principles that govern phacoemulsification can facilitate usage of this technique for effective and efficient cataract removal in a variety of clinical situations. This article addresses separately, concepts pertaining to the three essential components of phacoemulsification, namely, irrigation, aspiration and emulsification. Machine settings are suggested for the various techniques presently in use. Finally, alternative approaches for lens removal that are currently being investigated are briefly discussed.

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Reliable population-based epidemiologic data regarding vision and ocular morbidity, as well as those about the perceptions of people regarding visual impairment and eye care, are lacking for the most part in the developing world including India. These data are the basis on which effective eye care services can be developed. To meet this need we designed the Andhra Pradesh Eye Disease Study, a population-based epidemiology study of 10,000 people in the Indian state of Andhra Pradesh. The design of this study is described in this paper. Various options for the sample size, study areas, sampling procedure, and recruitment of subjects were considered. A sample size of 10,000 people, 5,000 each in the < or = 30 and > 30 years age groups, was determined to obtain reasonable confidence in estimating the prevalence of diseases and odds ratios for risk factors of interest. A multistage sampling strategy was chosen for the study which was assumed to give a design effect of 1.5 for the estimates. One urban area, Hyderabad, and three rural areas, West Godavari, Adilabad and Mahbubnagar districts, were selected in Andhra Pradesh. Interview instruments were developed to obtain detailed information about demographic data, diet, ocular and systemic history, risk factors for eye diseases, visual function, quality of life, barriers to eye care, and knowledge about eye diseases. A detailed examination procedure was devised to obtain a broad range of normative and abnormal data related to eyes and vision. A protocol was developed for doing automated visual fields, slitlamp and fundus photography. Computer databases were made in FoxPro for data entry and subsequent analysis with SPSS. Pilot studies were done to test the instruments, procedures, and logistics of the study in urban and rural areas. Information from the Andhra Pradesh Eye Disease Study is expected to help in planning and implementation of effective long-term preventive, curative, and rehabilitative eye care services in Andhra Pradesh.

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Antiviral drug development has been slow due to many factors. One such factor is the difficulty to block the viral replication in the cell without adversely affecting the host cell metabolic activity. Most of the antiviral compounds are analogs of purines and pyramidines. Currently available antiviral drugs mainly inhibit viral nucleic acid synthesis, hence act only on actively replicating viruses. This article presents an overview of some of the commonly used antiviral agents in clinical ophthalmology.

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The increasing popularity of phacoemulsification in our country raises important training issues. We prospectively analyzed the incidence of complications and visual outcomes in the initial 70 phacoemulsifications (70 patients) performed by the first two residents learning phacoemulsification in our training programme. Both were experienced in standard (manual) extracapsular cataract extraction. Postoperative follow up of 6 weeks or longer was available in 59 eyes. The 11 patients (11 eyes) lost to follow up did not have any intra-operative complications. The overall incidence of vitreous loss was 10%, similar to the frequency of this complication (determined retrospectively) in the first 70 standard extracapsular cataract extractions performed by the same residents. Intraocular lenses (IOL) were successfully implanted in 62 eyes, as planned. One IOL dislocated into the vitreous was successfully repositioned. Other complications encountered included superior corneal edema (3 eyes), iris damage inferiorly (7 eyes) and clinical cystoid macular edema (5 eyes). A best corrected visual acuity of 6/12 or better was obtained in 56 (94.8%) of the 59 eyes available for the six week follow up. In the eyes with vitreous loss, 6 out of 7 had visual acuity better than 6/12. No nuclei were lost into the vitreous. The rate of surgical complications for residents learning phacoemulsification in a supervised manner can be acceptably low.

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Patients for cataract surgery in India routinely undergo preoperative syringing to rule out chronic dacryocystitis. We determined the sensitivity and specificity of the clinical test of regurgitation on pressure over the lacrimal sac (ROPLAS) as a screening test for chronic dacryocystitis and compared it to syringing. 621 consecutive outpatients who needed syringing for various reasons (including 318 who had routine syringing prior to cataract surgery) were examined in a masked manner for regurgitation on pressure over the lacrimal sac. They then underwent syringing by a trained (masked) observer. The sensitivity and specificity of ROPLAS were 93.2% and 99.3%, respectively. Using a 6.6% prevalence of chronic dacryocystitis (the prevalence in our cataract population), the negative predictive value of the test was 99.5%. In the presence of regurgitation of pressure over the sac, the high specificity of ROPLAS confirms chronic dacryocystitis. In view of the opportunity costs, when ROPLAS is negative, preoperative syringing in cataract is perhaps unnecessary, unless the findings are equivocal or the index of suspicion for chronic dacryocystitis is very high.

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Effect of twice daily administration of aspirin eyedrops on the onset and progression of cataract induced by 30% galactose diet was studied. On the 30th day of galactose feeding while all control group rats showed complete stage IV opacity, those receiving aspirin eyedrops showed only mild cataractous changes of stage I. In vitro studies showed that addition of aspirin to the medium significantly decreased dulcitol formation (p < 0.01) and maintained glutathione levels (p < 0.02). Intraocular penetration studies using isolated goat cornea showed excellent penetration by salicylate indicating feasibility of topical administration. The results of the present study demonstrate that topical aspirin possesses significant anticataract activity in galactosemic cataract.

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The solubility characteristics of collagen in human cataractous eye lenses were studied in relation to age. Post-operative cataractous lenses were collected form eye camps in Phulbani district of Orissa. These were preserved in 70 % alcohol and immediately transferred to the laboratory. Various fractions in the collagen obtained from lens capsule of each lens sample were estimated. The salt-soluble and the acid-soluble collagens showed positive correlation with age. The insoluble and total capsular collagen increased with increasing age. The solubility percentage of collagen in salt and acid solutions decreased significantly with increasing age. The possible role of lens collagen in the development of cataract with increasing age is discussed in the background of cross-link theory of aging.

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