{'fraction_non_alphanumeric': 0.04059196617336152, 'fraction_numerical': 0.02029598308668076, 'mean_word_length': 4.6738609112709835, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 1, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Assessment of Contact Lens with the High Definition (HD) Property

Background: Contact lenses have been in use since the 1930s. During these years, many materials have been considered with the aim of producing more advanced and biocompatible devices. The 1940s was the era of the first modern contact lenses, with the debut of polymethyl methacrylate (PMMA). The lack of oxygen supply to the cornea was the main disadvantage of PMMA. This oxygen impermeability was solved with the development of different contact lens materials, new generation of contact lens use hydrogel and silicone to enhance oxygen permeability. Recently, the new contact lens material known as silicone hydrogel lenses has been used to produce a new lens with the HD property. Aim of Study: The aim of this study was to assess a new high definition silicone hydrogel contact lens. Patients and Methods: 22 subjects have been recruited from King Saud University students (male, age 21 ± 1.5 years). The new Balafilcon A lenses (PUREVISION 2 HD); (Bausch + Lomb, Tokyo, Japan) has been assessed and compared with another (non HD) silicone hydrogel lens Balafilcon A (PureVision, Bausch & Lomb Inc., Rochester, NY). The participants asked to wear each of the two lenses for one week (the lens was given randomly) and 48 hours wash out period was allowed between the lenses. Clinical tests including visual acuity (VA) and contrast sensitivity (CS) were applied to evaluate the lens performance at the end of each week. Additionally, contact lens dry eye questionnaire (CLDEQ-8) has been used to obtain the subjective feedback. Result: The mean of CLDEQ-8 with PureVision was 8.1 and with Pure Vision 2 HD was 6. For contrast sensitivity the mean with PureVision was 1.74 while with Pure Vision 2 HD was 1.77. The mean of Visual Acuity was equal with the two lenses 1.00 log. Statistical tests using Wilcoxon-signed rank test showed no significant difference exist between the HD PureVision 2 and PureVision lens. For Visual Acuity (p= 0.317), Contrast sensitivity (p=0. 150) (Fig. 2) and CLDEQ8 (p=0.339). Conclusion: The silicone hydrogel HD lens evaluated in this study showed good performance. However, no significant difference in clinical performance was observed between the HD lens and the non HD silicone hydrogel lens. Correspondence to: Dr. Raied A. Fagehi, E-Mail: Rfagehi@ksu.edu.sa