Effects of Aqueous-Supplementing Artificial Tears in Wearers of Biweekly Replacement Contact Lenses vs Wearers of Daily Disposable Contact Lenses.

PURPOSE: To compare the effects of artificial tears (ATs) in wearers of biweekly replacement silicone hydrogel contact lenses (BW-Ws) and wearers of daily disposable contact lenses (DD-Ws) of the same material. MATERIALS AND METHODS: The aqueous-supplementing ATs, OPTOyalA and OPTOidro, were assigned to be used for 2 weeks to healthy and young subjects: 1) 20 (8 and 12, respectively) BW-Ws wearing silicone hydrogel somofilcon A CLs (Clariti Elite), 2) 18 (9 and 9, respectively) DD-Ws wearing silicone hydrogel somofilcon A CLs (Clarity 1 Day), and 3) a control group of 33 (16 and 17, respectively) N-Ws. Ocular symptoms and comfort, tear volume and stability, and ocular surface condition were assessed by Ocular Surface Disease Index (OSDI), 5-Item Dry Eye Questionnaire (DEQ5), tear meniscus height (TMH), non-invasive tear break-up time (NIBUT), and evaluation of ocular redness (OR). The assessment was performed before and after 15 days of use of the ATs in the 3 groups (BW-Ws, DD-Ws, and N-Ws). RESULTS: No clear significant difference was noted in symptoms and signs between OPTOyalA and OPTOidro irrespectively of the group of people studied. ATs use for 15 days produced a significant improvement in DEQ5 and OR in DD-Ws (Δ=-34%, p=0.006; Δ=-23%, p<0.001) and in N-Ws (Δ=-21%, p=0.001; Δ=-10%, p=0.006) but not in BW-Ws (Δ=-5%, p=0.072; Δ=-2%, p=0.257). No significant change was noted for TMH. CONCLUSION: In young and healthy subjects, the aqueous-supplementing effect of the ATs under consideration is more a rinsing and tear replacem ent effect than an increase in tear volume, and it produces an improvement of the eye redness and ocular symptoms. Contact lens wear influenced the effectiveness of ATs in a way which is correlated with the CL replacement schedule.

In vitro glistening formation in IOLs: automated method for assessing the volumetric density and depth distribution of microvacuoles.

PURPOSE: To develop a method to measure the depth profile of microvacuoles (MVs) in intraocular lenses (IOLs) and to characterize, after accelerated aging, the glistening of an acrylic hydrophobic IOL. SETTING: University of Milano-Bicocca, Milan, Italy. DESIGN: In vitro study. METHODS: A heat treatment was applied in vitro to Basis V IOLs exposed to deionized water (24 hours at 45 ± 1°C, rapid cooling, and 24 hours at 24 ± 1°C). Thirty images (area 1.2 mm) of each IOL were acquired by a microscope, focusing on sequential planes every 23 ± 2 µm. By tracking the traces of each MV in consecutive images, the coordinates of the MV centroids along the IOL thickness were construed by an automated procedure, and in the generated single-focus stacked image, MVs were counted by an automated method. RESULTS: MV density was found normally distributed along the IOL depth profile (Jarque-Bera test). In focus-stacked images, the MV automated counting was found accurate within 5% vs manual counting, and MV volume density of the order of 10 mm was estimated. It was observed that stacks of 15 images provided a 4% lower MV volume density compared with the stacking of 30 images. CONCLUSIONS: The assessment of the number of MVs by the acquisition of a single image of an IOL was influenced by the distance of the selected plane from the IOL surface. The decrease in MV density approaching the IOL edges can be explained as a consequence of the diffusion of water toward the external environment after accelerated aging.

Slit-lamp based assessment of peripheral versus central regions of the human corneal endothelium.

PURPOSE: To compare the central and peripheral (< 2 mm from the limbus) endothelial regions of the human cornea of young contact lens (CL) neophytes, in terms of endothelial cell density (ECD), polymorphism through cell hexagonality (HEX), and polymegethism through the coefficient of variation of cell areas (CoV). MATERIALS AND METHODS: In vivo, central, temporal, and nasal ECDs, HEXs, and CoVs were determined for thirty healthy right eyes (age: 22-30 years) using a Takagi 700 G L LED slit-lamp biomicroscope equipped with the centre-dot EndoKer© for the analysis of endothelium images. RESULTS: The mean central ECD (2586 ±â€¯233 mm-2) was lower than peripheral ECDs (nasal 2733 ±â€¯225 mm-2, temporal 2674 ±â€¯260 mm-2) (p = 0.03 and p = 0.02, respectively). The mean central HEX (53.0 ±â€¯4.6%) was lower than peripheral HEXs (nasal 57.2 ±â€¯4.3%, temporal 57.1 ±â€¯4.5%) (both p < 0.005), while the mean central CoV (28.2 ±â€¯2.5%) was higher than peripheral CoVs (nasal 25.8 ±â€¯2.2%, temporal 26.1 ±â€¯2.2%) (both p ≤ 0.001). CONCLUSIONS: In young healthy non-CL wearers, the peripheral corneal endothelium displays a higher ECD and significantly better cell regularity (higher HEX and lower CoV) compared to the central cornea. A clinical evaluation of the corneal endothelium requires, therefore, a full characterization of the different areas.

Zeta potential of tear samples: A tool to explore the effects of wear of contact lenses.

PURPOSE: The aim was to develop a method to assess the electrostatic properties of human tear samples, and to evaluate their modifications induced by the wear of contact lenses (CLs). METHOD: The barrier method was developed for the measurement of the isoelectric point (IEP) on relatively small quantities. The method was applied to compare three groups: tears (TNW) of non-wearers, tears (TW_etaf) of regular wearers of etafilcon A CLs, and tears (TW_omaf) of regular wearers of omafilcon A CLs. Zeta potential (ζ) as a function of pH was measured by a Zetasizer Nano ZS90 (Malvern Instruments) on 40%-diluted samples, obtained by mixing 57 µL of tears of different subjects of the same group with 85 µL of HCl aqueous solution. IEP was deduced as the pH at which ζ is zero, i.e. the net electric charge on tear constituents being neutralized. RESULTS: Within an error of about 0.05, IEPs were found to be 2.90 (TNW), 2.80 (TW_omaf), and 3.16 (TW_etaf). On average, a lower H+ concentration is needed to neutralize the surface charge of the tear components of etafilcon A wearers, compared to both TNW and TW_omaf. CONCLUSION: IEP measurements on tear samples of wearers of different types of CLs are proposed in order to enhance the knowledge on the modifications of the profile of charged species in tears. The TW_etaf results, compared to those of the other groups, are compatible with an increase, due to the wear of etafilcon A CLs, of the relative concentration of high-IEP proteins.