Endothelial parameters in central and peripheral cornea in patients wearing contact lenses

AIM： To measure the parameters of endothelium in the central and peripheral parts of the cornea and evaluate the influence of wearing the hard and soft contact lenses on the mentioned parameters.METHODS： A specular microscope was used to measure the corneal endothelium parameters in both eyes of 139 Caucasians（a total of 278）. All participants were divided into three groups： soft lens wearers, hard lens wearers and a control group. Factors, such as age, smoking, types of lens material, duration of lens wear and lens air permeability were assessed to determine their impact on the morphometric parameters of the endothelium.RESULTS： A lower percentage of hexagon-like cells and higher cell variation than in other groups were determined in hard contact lens wearers. The difference in density of endotheliocytes between the groups was not observed. The measurements of the morphometric parameters in soft contact lens wearers did not depend neither on the duration of lens wear, nor on air permeability. The relation between the patients＇ age and the variation of endothelium parameters was determined in the group of hard contact lens wearers.CONCLUSION： Wearing hard contact lenses provokes pleomorphism and polymegethism of the corneal endothelium, while soft contact lenses do not impact any parameters of the endothelium, most likely due to higher air permeability.

Biochemical and Morphological Changes in the Lenses of Selenium and/or Vitamin E Deficient Rats

The activities of glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-R),superoalde dismutase (SOD) and the contents of malondialdehyde (MDA) and free radicals were measured, and the morphological changes were observed in the lens of control rats, selenium-deficient (SeD) and/or vitamin E deficient (VED) rats. The activities of GSH-Px in the lens of SeD rats decreased significantly. The GSH-Px activities of lens were positively related to erythrocytes selenium level. There was a free radical at g = 2.0015 in the rat lens of all groupe, but the content of free radicals in the lens of SeD group was significantly higher than that of the control group. The free radical content of lens was negatively related to erythrocytes selenium level, as well as the GSH-Px activities in the lens. In vitro, ultraviolet radiation caused the generation of another kind of free radical (g = 2.0097) in the lens of all groups, but the amount of the free radical in the lens of the SeD group was also significantly higher than that of the control group. The activities of SoD and GSSG-R in VED rat lens were significantly decreased. The amount of MDA in the lens of SeD and/or VED rats were significantly increased. The results showed that the decrease of antioaldative capability in the lenses of SeD and/or VED rats accelerated the lipid peroxidation and generation of free radicals. Although only early morphological changes in SeD and/or VED rat lens were observed, it is considered that selenium and vitamin E deficiency may be involved in the occurrence of cataract

Antioxidant Status in Persons With and Without Senile Lens Changes

Biochemical evidence on lens culture suggests that antioxidant nutrients can protect lens against peroxidation caused by radiation. A case-control study was carried out on 262 middle aged (45-54) and aged (55-64) subjects. The relationship between biochemical markers of antioxidant status and senile lens changes (including cataract) was examined in 131 subjects with senile lens changes and 131 control subjects with clear lens. Antioxidant status was measured using plasma and erythrocyte glutathione peroxidase, erythrocyte superoxide dismutase and catalase activity and plasma levels of vitamine E and vitamin A. Subjects were grouped by age and sex. The results were as follows: (1) The subjects with lens changes tended to have lower plasma levels of vitamin E and vitamin A, lower activity of several antioxidant enzymes and higher level of MDA. (2) The subjects with senile lens changes had significantly lower erythrocyte glutathione peroxidase level.(3) In the middle-aged group, subjects with senile lens changes were observed to have lower erythrocyte and plasma glutathione peroxidase level than those without senile lens changes.The results suggest that appropriate amount of antoxidant nutrients might be expected to prevent or retard the process of lens changes

A case of severe refractive changes induced by Galyfilcon A silicone hydrogel contact lenses

Dear Sir, I＇m Boris Severinsky from the New England College of Optometry, Boston, USA. I write you to present an interesting case of extreme refractive and corneal topography changes induced by daily wearing of Acuvue Advance （Johnson＆Johnson, Vision Care） contact lens （CL）.