Evaluating the cytotoxicity of contact lens multi-purpose solutions in an in vitro lens system

Purpose: To investigate the relative cytotoxic effects of contact lens multipurpose solutions on cultured crystalline lenses. Methods: A comparison of the fluorescence emission levels of cultured bovine lenses as affected by three hour experimental exposure to three contact lens multipurpose solutions (COMPLETE Moisture Plus, AMO; OPTI-FREE Express, Alcon; and ReNu MultiPlus, Bausch & Lomb) was carried out. The pre- and post-exposure fluorescence levels of the lenses were obtained and values were compared to baseline and control measurements. Results: The solutions yielded varying degrees of cytotoxicity, demonstrating significant (p < 0.01) reversible reduction of cellular viability levels of the cultured crystalline lenses as revealed by the degree of fluorescence emissions in the following order (OPTI-FREE Express > ReNu MultiPlus > COMPLETE MoisturePlus multi-purpose solutions) Conclusions: The results show that OPTI-FREE Express and ReNu MultiPlus solutions exhibited more cytotoxic effect compared to COMPLETE MoisturePlus solution. The findings support reports from previous clinical and laboratory studies. These results suggest that the in vitro approach herein presented would be a valuable system for relatively inexpensive and repeatable laboratory investigations of the possible ocular surface reactions of ophthal- mic solutions, cosmetics and pharmaceuticals at pre- and during commercial phases

Chromagen lenses and abnormal colour perception

Background: The Chromagen lens system comprises of tinted spectacle or contact lenses, each with a specific colour wavelength filter which controls the spectra of the light entering the eye. This study investigated whether spectacle-mounted Chromagen lenses would enhance colour perception in individuals with abnormal colour vision. Methods: The Ishihara colour test was used to test for colour vision deficiency (CVD) and also to evaluate the effect of the Chromagen spectacle lens on colour perception in 13 subjects. An Oculus Anomaloscope was used to confirm and sub-classify the types of CVD. Subjects comprised of school age children from the Riyadh area in Saudi Arabia. Results: The distribution amongst the male participants comprised two subjects with protanomaly, two with protanopia, five with deuteranomaly, and two with deuteranopia. Amongst the two female participants, one subject showed deuteranomaly, and one showed protanomaly. Different types of Chromagen spectacle lenses displayed some levels of colour vision enhancement depending on type of CVD. Conclusion: The findings support the notion that chromagen lenses could enhance colour vision perception in some cases of red-green colour vision defects. Clients with CVD should be managed on an individual case basis. (S Afr Optom 2011 70(2) 69-74

The impact of solar ultraviolet radiation on human health in sub-Saharan Africa

Photoprotection messages and ‘SunSmart’ programmes exist mainly to prevent skin cancers and, more recently, to encourage adequate personal sun exposure to elicit a vitamin D response for healthy bone and immune systems. Several developed countries maintain intensive research networks and monitor solar UV radiation to support awareness campaigns and intervention development. The situation is different in sub-Saharan Africa. Adequate empirical evidence of the impact of solar UV radiation on human health, even for melanomas and cataracts, is lacking, and is overshadowed by other factors such as communicable diseases, especially HIV, AIDS and tuberculosis. In addition, the established photoprotection messages used in developed countries have been adopted and implemented in a limited number of sub-Saharan countries but with minimal understanding of local conditions and behaviours. In this review, we consider the current evidence for sun-related effects on human health in sub-Saharan Africa, summarise published research and identify key issues. Data on the prevalence of human diseases affected by solar UV radiation in all subpopulations are not generally available, financial support is insufficient and the infrastructure to address these and other related topics is inadequate. Despite these limitations, considerable progress may be made regarding the management of solar UV radiation related health outcomes in sub-Saharan Africa, provided researchers collaborate and resources are allocated appropriately

Occupational exposure to optical radiation and the ocular health status of glassblowers

The occupational radiation exposure levels and the ocular health status of a sample of glass-blowers in southern Ontario were evaluated. The form of ocular protection was also assessed. Measurements of radiant emissions from different molten glass materials were carried out. A total of six glassblowing installations, 15 glassblowers and 42 non-glassblowers participated in the study. The spectral transmittances of samples of the protective lenses were obtained. Tonometry, biomicroscopy, ophthalmoscopy, pachometry. Schirmer tear test, endothelial photography were completed on all the volunteering subjects. The glassblowers' ocular findings were compared to those of non-glassblowers. No indication of cataract was observed among this group of glassblowers. Although, a preponderance of grade 2 polymegethism among the glass-blowers (47% compared to 11% in non-glassblowers) was found, there was no significant difference in their ocular health. Variation in the corneal irradiance from occupational exposure was obtained, and in addition, the use of protective lenses was found to be inappropriate. In order to prevent against any long-term chronic pathologic effect, the use of appropriate ocular protection is advised

Myopia Inducement by Hyperbaric Oxygen Treatment of Guinea Pigs

Purpose: Treatment of human patients with hyperbaric oxygen (HBO) is known to induce reversible myopia. The aim of this study was to 1) determine if HBO treatment could induce myopia in guinea pigs, and 2) determine whether a correlation existed between the in vivo refractive status of the eye and the in vitro focal length status of the lenses, post-HBO treatment. Methods: Animals were exposed to 100% O2 @ 2.5 atm for 2.5 hr periods, 3x a week with the total number of treatments at 35 or 70. Retinoscopy was performed on both eyes of treated animals and untreated controls before euthanasia. Nuclear light scatter was evaluated using slit-lamp biomicroscopy. Lenses were dissected and placed in a two-compartment 25 ml chamber containing culture medium supplemented with 1% penicillin/streptomycin and 3% fetal bovine serum. The optical quality of the lenses was measured using a real-time scanning laser system. Results: The lenses of the treated animals showed an increase in nuclear light scattering as shown by slit-lamp. The 35-HBO-treated animals showed significant myopia (treated, -6.00 diopters vs control, -0.50 diopters; P = 0.001) and the lenses showed shorter focal lengths (treated, 8.26 mm vs control, 8.86 mm; P = 0.034). While the 70-HBO-treated animals were not significantly different from the control for in vivo assessment, lens optical quality showed a significant decrease in the treated group (focal length variability: treated, 0.31 mm vs control, 0.15 mm; P = 0.02). Conclusions: These findings show that the 35-HBO-treatment caused myopia in guinea pigs, while at 70-HBO-treatment the response rate of the refractive system appeared to display some saturation with no significant myopia. However, the lenses from the 70-HBO-treated animals exhibited higher focal variability. A correlation between the in vivo and in vitro results is demonstrated. The shorter focal lengths in the 35-HBO-treated group suggest a lenticular role in the reversible HBO-induced myopia as reported elsewhere for humans

Colour vision screening among Saudi Arabian children

Purpose: To determine the prevalence of congenital red-green colour vision defects among Saudi Arabian male and female children. Methods: The study involved 1638 elementary and high school participants (838 males, and 800 females), who were randomly selected and screened for red-green colour vision defects using the Ishihara (pseudo-isochromatic plates) test. Inclusion criteria were Snellen VA 20/20 or better and absence of known ocular pathologies.Among the females, 0.75% of the 800 participants showed CVD, with 0.25% and 0.5% demonstratingprotan and deutan defects, respectively. Conclusion: The results show that the prevalence of red-green colour deficiency among the female children from central Saudi Arabia is not significantly different from that of female populations inwestern countries.  The current prevalence among the males is higher than previously reported for central Saudi Arabia, but less than for Caucasian populations

Solar ultraviolet radiation exposure and human health in South Africa: Finding a balance

In considering the likelihood of South Africa (SA) attaining the 2015 Millennium Development Goals, many health issues require urgent attention. The adverse effect of insufficient or excessive exposure to solar ultraviolet radiation (UVR) may exacerbate an already stressed public health service. These concerns become important when considering climate variability and patterns of behaviour

Assessment of the Medmont C100 test for colour vision screening of male Saudi Arabians

Purpose: To assess the Medmont C100 test as a colour vision screening tool. Methods: One hundred and seventeen young male adults were screened with the Medmont C100, Ishihara plates, and the screening mode of the Oculus Anomaloscope tests. All subjects were tested under constant room illumination, namely that of a day light fluorescent lamp at 200 lux. Inclusion criteria were visual acuities (VA) of 20/20 or better with or without correction and absence of known ocular pathologies.Aided and unaided visual acuities were measured with the Snellen VA chart. Results: Five out of the117 subjects, were found to have red-green colour vision deficiency (CVD) with Ishihara and anomaloscope tests indicating a 4.7% CVD prevalence, while the Medmont C100 test yielded 33 cases of red-green deficiency indicating CVD prevalence of 28%.  With the Ishihara test, all five subjects were identified as deutans, while the anomaloscope revealed three as deutans and two as protans, and the Medmont C100 test identified all 33 cases as protans. Conclusion:  The Medmont C100 test yielded significantly higher prevalence of protan CVD compared with the Ishihara platesand Anomaloscope tests. These findings suggest that caution should be taken when using Medmont C100 test for colour vision screening as it tends togive more false positive results with bias for protans.  (S Afr Optom 2011 70(1) 14-20

The impact of solar ultraviolet radiation on human health in sub-Saharan Africa

Photoprotection messages and ‘SunSmart’ programmes exist mainly to prevent skin cancers and, more recently, to encourage adequate personal sun exposure to elicit a vitamin D response for healthy bone and immune systems. Several developed countries maintain intensive research networks and monitor solar UV radiation to support awareness campaigns and intervention development. The situation is different in sub-Saharan Africa. Adequate empirical evidence of the impact of solar UV radiation on human health, even for melanomas and cataracts, is lacking, and is overshadowed by other factors such as communicable diseases, especially HIV, AIDS and tuberculosis. In addition, the established photoprotection messages used in developed countries have been adopted and implemented in a limited number of sub-Saharan countries but with minimal understanding of local conditions and behaviours. In this review, we consider the current evidence for sun-related effects on human health in sub-Saharan Africa, summarise published research and identify key issues. Data on the prevalence of human diseases affected by solar UV radiation in all subpopulations are not generally available, financial support is insufficient and the infrastructure to address these and other related topics is inadequate. Despite these limitations, considerable progress may be made regarding the management of solar UV radiation related health outcomes in sub-Saharan Africa, provided researchers collaborate and resources are allocated appropriately