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Query: UMLS:C0086543 (cataract)
 29,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The unopened eye maintains a relatively stable spherical contour due to the expansile influence of the intraocular pressure. When the eye is opened this expansile pressure is lost and some degree of collapse of the scleral shell ensues. In eyes with a relatively flaccid sclera an anterior segment incision may induce significant reduction in the volume of the posterior segment of the globe. During intracapsular cataract extraction on such eyes, scleral collapse can cause anterior displacement of the lens and iris when the eye is opened and vitreous loss as soon as the lens is extracted. Scleral collapse tends to occur during intraocular surgery on previously aphakic eyes. In this situation it may become difficult to achieve a vitreous-free anterior sement by open sky vitrectomy. Metallic scleral supporters prevent inward collapse of that portion of the sclera to which they are attached. They do not prevent downward collapse of the posterior sclera shell. Upward traction is required to prevent the downward component of scleral collapse. A system for controlled suspension of the globe during intraocular surgery has been devised and used in a variety of surgical procedures. The apparatus is simple and it does help to minimize downward scleral collapse. It does not prevent scleral identation or distortion by external forces and cannot substitute for inadequate anesthesia and akinesia or faulty surgical technique.
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PMID:Suspension of the globe during intraocular surgery. 75 77

Vitreous prolapse in cataract surgery or during the extraction of a dislocated lens; corneal dystrophy in aphacic eyes due to corneo-vitreous contact and vitreous invading the anterior chamber following perforating injury proved to be valid indications for partial transpupillary vitrectomy. In malignant glaucoma, in postoperative wound rupture following cataract extraction, in open-sky-surgery of the anterior segment of aphacic eyes and in other particular conditions, transpupillary vitrectomy may also be considered. The transpupillary approach is not indicated in retinal detachment, unless prepupillary vitreous incarceration pulling up of the retina is obvious. Transpupillary vitrectomy can be performed without much harm to the eye even in children, if indicated (congenital cataract, congenital on traumatic lens dislocation, perforating lens injury). In general the results of transpupillary vitrectomy are good. Longterm complications are relatively rare. Experiences on 208 eyes are reported in particular.
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PMID:[Results of transpupillar vitrectomy (author's transl)]. 91 5

Continuous tear capsulotomy, or capsulorhexis, permits secure and precise placement of a posterior chamber intraocular lens. This technique can be used open sky during triple procedures combining penetrating keratoplasty with cataract extraction and intraocular lens insertion. Expression of the nucleus through a continuous tear capsulotomy can be difficult. Incisions in the anterior capsule facilitate nucleus expression but can extend, obviating the advantages of continuous tear capsulotomy. With phacoemulsification using low irrigation and adequate ultrasound power, the nucleus can be completely emulsified or fragmented into easily removable pieces. This permits continuous tear capsulotomy to be part of triple procedure surgery.
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PMID:Continuous tear capsulotomy and phacoemulsification cataract extraction combined with penetrating keratoplasty. 191 17

Simplified manual forms of extracapsular cataract extraction appear to be more economical, yet as safe and simple as techniques employing more complex instrumentation. The following method, employed in 40,000 cases, seems to the author to be an efficient and effective way of performing cataract extraction. One hour prior to surgery, modified retrobulbar anesthesia alone is employed using the technique described, and provides adequate akinesia as well as anesthesia. Positive pressure is applied to the eye preoperatively to assure softness of the globe at the time of surgery. An anterior capsulectomy is made with scissors, using the open-sky technique. Following the delivery of the lens nucleus and as much cortex as possible with a lens loop, the remaining cortex is removed with an angled, 23-gauge, double irrigation-aspiration cannula. Filtered balance salt solution, containing gentamycin flows into the eye through the side port (inflow) and a 3-cc syringe with 2 cc BSS for irrigation-aspiration is connected to the other (aspiration) port. A single, 25-gauge, angled irrigation cannula is used to clean up the finger cortical remains. A firm-loop intraocular lens is inserted into the capsular bag. The posterior capsule is left intact.
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PMID:My method of extracapsular cataract extraction with implantation of a posterior chamber intraocular lens. 402 61

A 20-gauge intravitreal cryoprobe designed for endocryopexy during trans pars plana vitrectomy is now available. The probe may also be used for intracapsular cataract extraction and open-sky intravitreal cryopexy.
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PMID:A 20-gauge intravitreal cryoprobe. 742 41

The main intraoperative difficulties of performing a procedure combining open-sky extracapsular cataract extraction, implantation of posterior chamber intraocular lens (PC-IOL), and penetrating keratoplasty ("triple procedure"), most frequently caused by the uncompensated posterior pressure created when the cornea is open, include incomplete capsulorhexis, incomplete aspiration-irrigation of the cortex, uncertain placing of the IOL, posterior capsule rupture, choroidal effusion, and even expulsive hemorrhage. We recommend a two-step procedure that eliminates these problems: The first step begins with removal of epithelium, half-thickness trephining of the cornea, and capsulorhexis; proceeds through phacoemulsification and aspiration-irrigation; and ends with implantation of the PC-IOL, using a pressurized system. The second step is penetrating keratoplasty. In the six cases undergoing this procedure, none of these complications developed or even tended to develop. Although the follow up in these six cases is very short (from 1 to 6 months), the advantage of the technique is that it effectively precludes the above mentioned intraoperative complications, which could affect late results.
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PMID:Closed-system phacoemulsification and posterior chamber implant combined with penetrating keratoplasty. 833 92

There is currently some degree of controversy as to the magnitude of cataract and other ocular diseases related to human lifetime exposure to UV radiation (UVR). Concerns about the depletion of stratospheric ozone and the related increase in terrestrial UVR exposure have emphasized the importance of resolving this controversy. A careful study of ocular exposure to environmental sunlight demonstrates that it is not simple to determine accurately the level of solar UVR exposure of the human eye. Past attempts to measure or calculate UVR exposure of the eye have generally relied on the measurement of ambient UVR in sunlight with global monitors. Unfortunately, such attempts have seldom assessed properly the large role of ground reflection, the horizon sky contribution, the degree of lid opening and the extreme lateral component of UVR incident on the eye. A series of recent ocular dosimetry studies are described which have considered all of these factors. In addition, the value of different types of eye protection is shown to vary widely depending on the frame design. The dosimetry studies can be confirmed by a biological dosimeter--the human cornea. Because the action spectrum and threshold for human photokeratitis are well defined, the living cornea can serve as a biological dosimeter for ocular exposure.
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PMID:UV radiation ocular exposure dosimetry. 856 5

To highlight indications, technique, and advantages of closed-chamber phacoemulsification and intraocular lens (IOL) implantation during penetrating keratoplasty for corneal opacities. Case reports of 2 patients who underwent combined phacoemulsification, IOL implantation and penetrating keratoplasty. The technique described allowed controlled capsulorrhexis, cataract removal and in-the-bag IOL implantation. Complications due to increased posterior pressure during open-sky extracapsular cataract were not encountered. The surgical technique described in this report can only be used in selected patients undergoing combined corneal transplant and cataract surgery. In this group of patients, however, the technique offers many intra- and postoperative advantages.
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PMID:Combined phacoemulsification and penetrating keratoplasty. 1039 40

The intensity of UV-A and UV-B-radiation in Switzerland shows big differences that result from the various altitudes, the season and the time of the day. Additionally the intensity of UV-radiation is influenced by other factors like aerosols, cloudiness and ozone. In higher altitudes there is an additional enhancement by reflection of snow. The most important consequences of the UV-radiation for the population are, however, relevant in spring and summer time during the bathing season and during the late winter season for ski tourists. On a day with a clear sky in summer the UV-radiation can reach maximum values for UV-A of 45 W/m2 and for UV-B of 0.175 W/m2. The ratio of UV-A/UV-B shows an annual course with a maximum in winter of about 500 and a minimum of about 220 in summer. The possible effects on health by extensive UV-exposition are photoageing, skin cancer, inflammation processes and cataract. In Switzerland about 5000 new melanoma cases in men and about 4000 in women occur per year. In contrast to other environmental factors like pollen UV-radiation has the big advantage that the personal exposition can be controlled. Therefore, it is very essential that the general rules of a judicious behaviour such as avoiding the sun at noon, always wearing a hat, shirt and trousers as well as sunglasses with UV-filter are often reiterated.
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PMID:[UV exposure in Switzerland: time- and topography-associated factors important for the skin]. 1041 51

Epidemiological studies of the influence of environmental ultraviolet radiation (UVR) in the development of cataract, pterygium, droplet keratopathies and age-related macular degeneration have produced inconsistent findings. The lack of consistent results may be due largely to either incomplete or erroneous estimates of outdoor UV exposure dose. Geometrical factors dominate the determination of UVR exposure of the eye. The degree of lid opening limits ocular exposure to only those rays entering at angles near the horizon. Clouds redistribute overhead UVR to the horizon sky. Mountains, trees and building shield the eye from direct sky exposure. Most ground surfaces reflect little UVR. The result is that the highest UVR exposure occurs during light overcast where the horizon is visible and ground surface reflection is high. By contrast, exposure in a high mountain valley with green foliage results in a much lower ocular dose. Other findings of these studies show that retinal exposure to light and UVR in daylight occurs largely in the superior retina.
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PMID:Geometrical assessment of ocular exposure to environmental UV radiation--implications for ophthalmic epidemiology. 1070 47


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