Spectral transmittance of UV-absorbing soft and rigid gas permeable contact lenses

Increasing evidence of acute and chronic ocular effects of ultraviolet (UV) radiation has prompted some manufacturers to develop UV-absorbing rigid and soft contact lens materials. Currently, eight different lenses containing UV-absorbing agents are available in Canada. The spectral transmittance of a sample of these UV-absorbing contact lenses was measured in order to determine if all of them provide adequate protection from wavelengths in the UV spectrum. The sample consisted of 1 lens of each type. Cibasoft Ultrabloc; Permaflex UV; Boston RXD and Equalens; Alberta S; FluoroPerm 30, 60, and 92. A Philips single beam spectrophotometer was used. The lens under test was placed in a silica wet cell filled with unpreserved saline. Spectral transmittance was measured at 0.8-nm intervals over the waveband 200 to 800 nm. The results were recorded by a microcomputer interfaced to the spectrophotometer. The repeatability of spectral transmittance measurements of contact lenses using this method varied between 0% and +/- 1.55% of transmission depending on lens material and wavelength studied. The results showed that none of the rigid gas permeable (RGP) lenses, except the Alberta S, transmitted more than 0.1% (the sensitivity limit of the spectrophotometer) up to 380 nm. The Alberta S exhibited transmittance windows in the UV spectrum with peaks at 270 nm (23%) and 318 nm (29%). The Cibasoft Ultrabloc transmitted less than 1% up to 344 nm, whereas the Permaflex UV had a transmittance window in the waveband 240 to 316 nm with a maximum of 17% at 270 nm.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of topical anesthetic use on initial patient satisfaction and overall success with rigid gas permeable contact lenses

BACKGROUND: Rigid gas permeable (RGP) contact lenses have numerous benefits; however, RGP lens use is not increasing in the United States. An important factor for this trend has been initial comfort. Studies have demonstrated that how RGPs are presented to patients, in addition to lens design, can play an important role in the initial comfort process. Another important factor could be the use of a topical anesthetic during the fitting and dispensing visits. The purpose of this study was to use a multicenter format to determine if topical anesthetic use increased the likelihood of patient satisfaction and success. METHODS: A total of 80 subjects, with no previous rigid lens wear experience, was entered into this 1-month study, including 20 subjects from each of 4 institutions. Subjects were randomly divided into the following two groups: (A) anesthetic or (B) placebo, with the former group receiving one drop of a topical anesthetic before lens insertion at both the diagnostic fitting and dispensing visits, whereas the latter group received a placebo. Subjects completed a questionnaire on their perception of rigid lens wear both immediately before fitting and at the 1-month visit. After diagnostic fitting with rigid lenses, subjects completed an adaptation questionnaire after 15 min, 1 week, 2 weeks, and 1 month of lens wear. RESULTS: Seventy of the 80 subjects completed the study and, of the 10 subjects who discontinued, 8 were in the placebo group. In all categories evaluated, the anesthetic group experienced a more optimum adaptation experience at each visit vs. the placebo group. Specifically, overall comfort was rated significantly higher at both dispensing and 2 weeks. In addition, the anesthetic group exhibited significantly greater overall satisfaction with rigid lens wear at 2 and 4 weeks. Also, the anesthetic group perceived their adaptation, sensitivity, and adaptation time to be significantly better at the 1-month visit. There was no significant difference in corneal staining between these two groups at each visit, with the exception of a greater amount of staining in the central quadrant for the placebo group at the 1-month visit. CONCLUSIONS: The use of a topical anesthetic at the fitting and dispensing visits for first-time wearers of RGP lenses resulted in significantly fewer dropouts, improved initial comfort, an enhanced perception of the adaptation process, and greater overall satisfaction after 1 month of lens wear as compared to the use of a nonanesthetizing placebo at those visits. This result, in combination with both presenting RGP lenses in a nonthreatening manner and optimizing the lens design and fitting relationship, should result in a positive adaptation process and successful wear of RGP contact lenses.     

Uniocular aphakia--conventional contact lenses and aniseikonia

Ehrich and Kolbegger show in their papers that aniseikonia should not prevent binocular functions in a uniocular aphakia. This is contrary to our own experiences. In this paper we suggest that the results of Ehrich and Kolbegger must be worse in spite of their final conclusions. Their hypotheses are discussed.     

Disposable contact lenses and their complications

Disposable soft contact lenses (DSCLs) have been marketed as a safer alternative to conventional soft lenses. Extended-wear DSCLs are designed for one or two weeks of continuous use before disposal. Those for daily wear are designed for use as conventional daily wear soft lenses, with daily removal and storage for 2 to 4 weeks before disposal. Beside minor complications, such as corneal abrasion, giant papillary conjunctivitis and toxic epithelial reactions to contact lens solutions, the most serious complication occurring in contact lens users is ulcerative keratitis. Several case-control studies performed over the last years, demonstrated that disposable contact lenses were associated with a 14-fold excess risk of ulcerative keratitis compared with that for patients wearing conventional daily-wear soft contact lenses and a 13-fold excess risk compared with that for wearers of rigid gas permeable contact lenses. However, the major risk factor for corneal ulceration in contact lens wearers is overnight lens wear of 1 to 3 nights. It was estimated that 49 to 74% of cases of contact lens associated ulcerative keratitis could be prevented by eliminating overnight wear.     

Comparison of a videokeratoscope and an autokeratometer as predictors of the optimum back surface curves of rigid corneal contact lenses

Vasoactive intestinal polypeptide (VIP) is reported to exert an autocrine control on neuroblastoma cell tumours: VIP is produced by the tumour and stimulates cell differentiation. This study tested the hypothesis that the parent peptide; the pituitary adenylate cyclase activating polypeptide (PACAP) may have a similar role. It was found that PACAP mRNA and PACAP were expressed in 12/12 tumours; it was also observed that PACAP receptor mRNA and functional PACAP receptors were expressed in 12/12 and 5/9 tumours, respectively. VIP mRNA and VIP were detected in 9/12 tumours. VIP receptor mRNA was expressed in 5/12 tumours and functional VIP receptors were never demonstrated. The tumours having the highest VIP levels also had the highest PACAP contents and were associated with a watery diarrhoea syndrome due to activation of intestinal VIP receptors. As PACAP recognizes the PACAP receptors and the VIP receptors with the same high affinity it may contribute to the syndrome and is a likely candidate for an autocrine control of neuroblastoma cell growth and differentiation.     

Centration mechanism of soft contact lenses

A theoretical model is developed in which the force that restores a soft hydrogel lens to its centered position is ascribed to flexure of the lens. It is shown that flexure makes the dominant contribution to the strain energy in the displaced position. The restoring force is calculated explicitly. The return speed is estimated explicitly, assuming that the dominant resisting force is the viscous drag offered by the postlens tear film. Satisfactory agreement with observations is found.     

Life expectancy of adults with cerebral palsy

The aim of this study was to investigate interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) production by peripheral blood mononuclear cells (PBMC) in response to oral challenge in patients with food allergy. Thirty-one patients were compared with 10 healthy subjects. Cell cultures were prepared before and 150 min after single-blind, placebo-controlled, oral food challenge. In vitro production of cytokines was observed after stimulation with phytohemagglutinin (PHA) plus phorbol myristate acetate (PMA). Patients were characterized according to their reactions. In vitro IL-4 production was significantly greater in patients with food sensitization than in controls. The 18 patients with positive food challenge presented significantly greater IL-4 production after food challenge than before. IFN-gamma production was not modified. In the 10 control subjects and in 13 patients with negative food challenge, IL-4 and IFN-gamma production was comparable before and after food challenge. The increased IL-4 production in patients with positive oral food challenge could account for the development of polysensitization. This situation might be relevant to other allergic diseases and to treatments.     

Interactions of bacteria with contact lenses: the effect of soluble protein and carbohydrate on bacterial adhesion to contact lenses

OBJECTIVE: To investigate the effects of cold application with different temperatures on lymph flow in healthy persons and to examine the effects of the combination of cold and compression on lymph vessels. PARTICIPANTS: Thirty-nine healthy persons were included in the study, and each served as his or her own control. INTERVENTION: Water bags (1 degree, 15 degrees, and 32 degrees) with or without 25 mm Hg pressure were applied to the experimental legs for 30 minutes. Cold, pressure, or both were administered by an Aircast-Cryo-cuff (Aircast Europe GMBH, Rosenheim, Germany). MAIN OUTCOME MEASURES: Skin temperature was measured with a TESTO 901 (Testoterm GMBH, Leuven, Belgium) precision thermometer. Lymph flow was recorded continuously using lymphoscintigraphy. MANOVA with repeated measures was used for data analysis. RESULTS: As expected, skin temperature dropped relative to the temperature of the water. The migration of the tracer was comparable in both ankles during the first 30 minutes of the experiment (rest). When the water bag was applied, lymph flow increased significantly (p < 0.01). The application of water of 1 degree C without pressure influenced lymph evacuation significantly differently from the other temperatures. The application of pressure of 25 mm Hg influenced lymph evacuation significantly at 1 degree C and 32 degrees C. CONCLUSION: These results indicate that lymph evacuation at the ankle is influenced significantly when cold water is applied with or without pressure. When pressure is added to the application of water of 32 degrees C, lymph flow will also increase significantly, indicating the importance of pressure in lymph evacuation.     

Life expectancy and cost utility after total hip replacement

In a prospective study of 410 cemented hip replacements in 372 patients with a mean age of 71 years, mortality after 8 years was 33%. Mortality for patients with osteoarthrosis was lower than in an age matched control population, probably because of a preoperative selection of patients. An estimate of costs and adjusted quality of life has shown that total hip replacement has a good cost utility even in the elderly patient. The conclusion of this study is that the indications for hip replacement in the elderly patient can be expanded. Such patients should undergo surgery earlier in the course of their disease.     

Alcohol expectancy priming and drinking behavior: The role of compatibility between prime and expectancy content.

According to information-processing models of alcohol use, alcohol expectancies constitute representations in long-term memory that may be activated in the presence of drinking-related cues, thereby influencing alcohol consumption. A fundamental implication of this approach is that primed expectancies should affect drinking only for those individuals who possess the specific expectancies primed. To test this notion, in the present study, participants were initially assessed on 3 distinct domains of positive alcohol expectancies. Approximately 1 week later, they completed an ad libitum drinking study during which only a single expectancy domain (sociability) was primed in the experimental condition. Consistent with predictions, following exposure to sociability primes but not control primes, individuals with stronger expectancies that alcohol would enhance sociability uniquely showed increased placebo consumption of nonalcoholic beer. These results, which demonstrate the moderating role of compatibility between the specific content of primes and that of underlying expectancies, offer new, direct support for memory network-based models of drinking behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Life expectancy of mentally retarded persons in Canadian institutions

Data obtained from Statistics Canada were presented on the mortality level and expectancy of life for profoundly retarded and severely and moderately retarded persons in Canadian institutions for the years 1966 through 1968. Previous studies of mortality statistics were reported in mortality rates, average age at death, and crude death rates which are affected by the age distribution of the population involved. The very young and the very old are underrepresented in institutions, and thus these measures are not as accurate as life expectancy tables, which present the number of years expected to live, are independent of age distribution, and provide a reliable statistical measure for future replication and international comparisons. Retarded persons in institutions are living longer than previously, but their life expectancy does not meet that of the general population. Estimates of life expectancy for this population are vital for planning purposes.     

Life expectancy in Norway. An international perspective--causes of death

We have shown before that Norway is experiencing an unfavourable trend in life expectancy compared with Japan, France and several other OECD countries. In this article, we discuss the cause-specific differences in mortality that explain these contrasts. Heart infarction is the predominant cause of death in Norway, with a mortality five times higher than in Japan and three times higher than in France. Both Norway and France have three times higher mortality rates for breast cancer than found in Japan, and the mortality rate for cervical cancer is twice as high in Norway as in the two other countries. Norwegian women show a mortality rate for lung cancer that is twice as high as that of their French sisters. Suicide among young Norwegians is a rapidly growing problem, and twice as common among Norwegian men aged 20-24 than among Japanese men of the same age. We challenge the health authorities and the specialists in the relevant fields to reflect again on their preventive strategies, in light of these contrasts.