Nanoscale Observation of Dehydration Process in PHEMA Hydrogel Structure.

One of the most important field of interest in respect to hydrogel materials is their capability to water storage. The problem mentioned above plays an important role regarding to diffusion of fluid media containing nanoparticles, what is very useful in biomedical applications, such as artificial polymeric implants, drug delivery systems or tissue engineering.In presented work, dehydration process in hydrogels used in ophthalmology as intraocular lenses was observed. Before measurements studied materials were immersed in deionized water and saline solution to obtain equilibrium swelling state. Studies of the dehydration process were carried out by use of gravimetric analysis, Fourier-Transform Infrared and Positron Annihilation Lifetime Spectroscopy. Obtained results revealed changes in hydrogen bonding structure and free volume holes induced by saline solution ingredients.

Study of free volumes of polymer hydrogel and -silicone-hydrogel contact lenses by means of the positron annihilation lifetime spectroscopy method.

BACKGROUND: Polymer materials based on hydrogel and silicone-hydrogel materials are commonly used in ophthalmology. It is important to research the structure of these materials, mainly the prevalence of free volumes. OBJECTIVES: The study has been conducted in order to determine the presence of free volume gaps in the structure of polymer hydrogel and silicone-hydrogel contact lenses. In addition, to demonstrate differences in the occurrence of free volumes between types of represented contact lenses. MATERIAL AND METHODS: Three different hydrogel and three different silicone-hydrogel polymer contact lenses were used as research material. The study was done by means of positron annihilation lifetime spectroscopy (PALS). RESULTS: As a result of the performed measurements, a graphical curve resulted which describes the relationship between the number of the annihilation acts in the time function. The study revealed the existence of three τ1, τ2 and τ3 components. Significant changes were observed in the ortho-positronium long life component τ3 and their intensities between the examined polymer contact lenses. CONCLUSIONS: The conducted study using the Tao-Eldrup model indicates the presence of free volume holes in all research materials. The results lead to the following connection: contact lenses of higher oxygen permeability coefficient (silicone-hydrogel contact lenses) have more and larger free volumes than contact lenses of less oxygen permeability coefficient (hydrogel contact lenses).

Investigation of free volume changes in the structure of the polymer bifocal contact lenses using positron lifetime spectroscopy PALS.

Positron annihilation lifetime spectroscopy PALS has been applied of free volume properties in bifocal contact lenses. The measurements have been made on new lenses and then after one, two, three and four weeks wear. The longest lifetime, obtained via three-component analyses of the spectra, was associated with the pick-off annihilation of ortho-positronium trapped in the free volume. After wear of the lenses changes in the ortho-positronium lifetimes and the relative intensity of the longest component were observed. These results are discussed on the basis of a free volume model.

[Investigation of free volume changes in the structure of the polymer bifocal contact lenses by means of the positron annihilation method]. / Badanie zmian wolnych objetosci w strukturze polimerowych dwuogniskowych soczewek kontaktowych metoda anihilacji pozytonów.

Positron annihilation lifetime spectroscopy has been applied of free volume properties in bifocal contact lenses. The measurements have been made on new lenses and then after one, and two weeks wearing by the patient. The longest lifetime, obtained via three-component analyses of the spectra, was associated with the pick-off annihilation of ortho-positronium trapped in the free volume. After one, and two weeks wearing of the lenses changes in the ortho-positronium lifetimes and the relative intensity of the longest component were observed. These results are discussed on the basis of a free volume model.

[Phacoemulsification of subluxated opacified lens in pseudoexfoliation glaucoma patients, performed with the use of a capsular tension ring and iris retractors]. / Fakoemulsyfikacja podwichnietych zmetnialych soczewek u chorych z jaskra pseudoeksfoliacyjna z zastosowaniem pierscienia dotorebkowego i retraktorów teczówkowych.

PURPOSE: To evaluate results of phacoemulsification of subluxated lens in patients suffering from pseudoexfoliation-related cataract and glaucoma, performed with the use of a capsular tension ring (CTR) and iris retractors and implantation of artificial intracapsular lens. PATIENTS AND METHODS: The retrospective covered 15 patients (15 eyes) at the average age of 75 years, with a subluxated, cloudy lens and pseudoexfoliation glaucoma with IV PEX. Due to poor mydriasis resulting from the course of the pseudoexfoliation syndrome, it was necessary with all the patients to apply iris retractors in order to enlarge the pupil. The opacified lens were removed by means of phacoemulsification. In order to provide additional peripheral support and to maintain the artificial lens in the central position after the surgery, a tension ring was implanted into the lenticular capsule. A foldable intraocular lens was implanted inside the capsule. RESULTS: The observation period was 12 months. The average visual acuity prior the surgery was 0.18+/-0.2, while after a year after the surgery it was 0.56+/-0.32 (p<0.001). Besides, the intraocular pressure was observed to decrease from 18.2+/-5.02 mm Hg before the surgery to 15.8+/-0.84 mmHg (p<0.001) after the surgery. The anti-glaucoma medication ratio was also reduced from 2.1 to 1.3 in the post-surgery period. Inflammatory reaction of the anterior chamber was observed in 7 eyes. CONCLUSIONS: Application of a CTR and iris retractors during a surgery of cataract in patients with subluxated opacified lens considerably facilitates the implantation procedure of an artificial lens into the capsule, and it allows to improve the visual acuity and stabilize the intraocular pressure while reducing the quantity of the applied anti-glaucoma drugs.

[Phacotrabeculectomy in patients with cataract and chronic open angle glaucoma, and patients with cataract and pseudoexfoliation glaucoma]. / Fakotrabekulektomia w leczeniu zacmy z jaskra pierwotna otwartego kata oraz zacmy z jaskra pseudoeksfoliacyjna.

PURPOSE: To compare the results obtained after phacotrabeculectomy followed by implantation of an intracapsular lens in patients with cataract and chronic open angle glaucoma, and patients with cataract and pseudoexfoliation open angle glaucoma. MATERIAL AND METHODS: The retrospective study covered 55 eyes with cataract and glaucoma. In 28 eyes, chronic open angle glaucoma was diagnosed, and in 27--pseudoexfoliation glaucoma. In all cases, phacoemulsification of the opacified lens was carried out, a foldable intraocular lens was implanted in the capsule, and the trabeculum was removed by means of a punch. Visual acuity, intraocular pressure and the ratio of applied anti-glaucoma drugs were subject to the assessment. RESULTS: The observation period was 12 months. Within the COAG patient group, the average visual acuity prior to the surgery was 0.2+/-0.24, and after one year from the surgery it increased to 0.82+/-0.22. For PEX glaucoma patients, the values were respectively 0.3+/-0.25 before the surgery and 0.75+/-0.29 a year after it. Considerable reduction of the intraocular pressure was also achieved: in the COAG patients--from 19.51+/-3.8 mm Hg to 16.6+/-1.6 mm Hg, and in PEX glaucoma patients--from 22.28+/-5.18 mm Hg to 17.6+/-2.33 mm Hg one year after the surgery. Also, the quantity of anti-glaucoma drugs applied in the study groups was significantly reduced. The anti-glaucoma drug ratio in the COAG patients dropped from 1.8 to 0 after the surgery, and in the PEX glaucoma patients--from 2.3 to 0.3. CONCLUSIONS: Phacotrabeculectomy is an efficient and safe surgical method, to be recommended for patients both with primary open angle glaucoma and with pseudoexfoliation glaucoma.

[Frequency doubling perimetry in diagnosis of early glaucomatous optic nerve fiber damage]. / Perymetria zdwojonej czestotliwosci w diagnostyce wczesnej neuropatii jaskrowej.

PURPOSE: The comparative evaluation results of frequency doubling technology (FDT) in healthy subjects, in patients with glaucoma suspected and glaucoma, as well as analysis influences of selected risk factors onset, and progression of glaucoma (age, gender, intraocular pressure, refractive errors, circulation system disease, diabetes mellitus, vasospastic vascular disease) on FDT-parameters. MATERIAL AND METHODS: Sixty four patients (128 eyes), in age between 13-80, with refraction error from -14.5 to +6.5 D sph and average intraocular pressure 19.8 +/- SEM were included in this study. All patients were previously diagnosed towards glaucoma. The visual field testing with help of FDT Visual Field Instrument were made at least triple at all patients, with capitalize on the THR N-30 threshold program. Global indices: mean deviation (MD) and pattern standard deviation (PSD) and numerical value of mean retinal sensitivity for central visual field 5 degree sector (mean sensitivity to central 5 degrees--MS 5 degrees) come in comparative analysis. All data were analyzed by chi2 and Kruskal-Wallis tests. RESULTS: Comparative analysis examined groups of healthy persons, patients with glaucoma suspect and glaucoma, it proves statistically significant difference between MD, PSD and MS 5 degrees. Statistically no significant difference between PSD and MS 5 degrees at groups of healthy and glaucoma suspect patients was detected. In glaucoma group there did not reveal an influence on selected risk factors on FDT parameters. However, in glaucoma suspect group revealed an influence on most risk factors on perimetry parameters. CONCLUSIONS: FDT is useful for detection of glaucomatous nerve fiber damage. There should be taken precautions of interpretation FDT results at glaucoma suspect patients.