Willcox M.D.P.,Brien Holden Vision Institute
Clinical and Experimental Optometry | Year: 2011
Background: Microbial keratitis is a rare disease but most commonly caused by bacterial infection. Two of the most common bacteria to cause microbial keratitis are Pseudomonas aeruginosa and Staphylococcus aureus. Antibiotic therapy to treat keratitis caused by these bacteria is either monotherapy with a fluoroquinolone or combination therapy with fortified gentamicin. Methods: Literature searches were made in Medline and Pubmed using the search terms [Pseudomonas] or [Staphylococcus] and [fluoroquinolone] or [cephalosporin] or [gentamicin] and [keratitis] or [cornea]. Rates of resistance to ciprofloxacin, gentamicin or cephalosporins were then compared for isolates from different geographic regions. Results: There are low resistance rates of P. aeruginosa and S. aureus to ciprofloxacin in isolates from Australia. Isolates from the Indian subcontinent are more commonly resistant to ciprofloxacin, with resistance rates of greater than 20 per cent being reported. Data from USA and Europe indicate that if the S. aureus is a methicillin resistant strain, then resistance to ciprofloxacin increases, often to greater than 80 per cent of isolates. Resistance to gentamicin and cephalosporins is also generally low in isolates from Australia. Again resistance is increased in isolates from the Indian subcontinent, as well as from South America. Conclusion: In Australia, the major ocular pathogens are generally sensitive to the most commonly used antibiotics to treat microbial keratitis. The prescription of fluoroquinolones, aminoglycosides and cephalosporins is generally reserved for treatment of significant or sight-threatening conditions such as microbial keratitis. This approach is not likely to contribute to an increase in resistance rates. © 2010 The Author. Clinical and Experimental Optometry © 2010 Optometrists Association Australia. Source
Tilia D.,Brien Holden Vision Institute
Optometry and Vision Science | Year: 2016
PURPOSE: To compare the objective and subjective visual performance of a novel contact lens which extends depth of focus by deliberate manipulation of higher-order spherical aberrations and a commercially available zonal-refractive multifocal lens. METHODS: A prospective, cross-over, randomized, single-masked, short-term clinical trial comprising 41 presbyopes (age 45 to 70 years) wearing novel Extended Depth of Focus lenses (EDOF) and ACUVUE OAYS for Presbyopia (AOP). Each design was assessed on different days with a minimum overnight wash-out. Objective measures comprised high-contrast visual acuity (HCVA, logMAR) at 6 m, 70 cm, 50 cm, and 40 cm; low-contrast visual acuity (LCVA, logMAR) and contrast sensitivity (log units) at 6 m; and stereopsis (seconds of arc) at 40 cm. HCVA at 70 cm, 50 cm, and 40 cm were measured as “comfortable acuity” rather than conventional resolution acuity. Subjective performance was assessed on a 1–10 numeric rating scale for clarity of vision and ghosting at distance, intermediate and near, overall vision satisfaction, ocular comfort, and lens purchase. Statistical analysis included repeated measures ANOVA and paired t tests. RESULTS: HCVA, clarity of vision, and ghosting with EDOF were significantly better than AOP (p < 0.01); however, differences were dependent on testing distances and add groups. Post hoc analysis showed EDOF was significantly better than AOP for HCVA at 70 cm (0.11 ± 0.11 vs. 0.21 ± 0.16, p < 0.001), 50 cm (0.26 ± 0.17 vs. 0.36 ± 0.18, p = 0.003), 40 cm (0.42 ± 0.17 vs. 0.52 ± 0.21, p = 0.001), and LCVA at 6 m (0.22 ± 0.08 vs. 0.27 ± 0.12, p = 0.024). EDOF was significantly better than AOP for clarity of vision at distance (7.7 ± 1.6 vs. 6.8 ± 2.3, p = 0.029), intermediate (8.8 ± 1.4 vs. 7.0 ± 2.2, p < 0.001), and near (7.4 ± 2.4 vs. 5.2 ± 2.7, p < 0.001), ghosting at distance (9.1 ± 1.2 vs. 8.1 ± 2.5, p = 0.005), and overall vision satisfaction (7.6 ± 1.6 vs. 6.0 ± 2.6, p < 0.001). More participants chose to purchase EDOF compared to AOP (61 vs. 39%) and significantly more chose to only-purchase EDOF compared to only-purchase AOP (27 vs. 5%, p = 0.022). CONCLUSIONS: When compared with AOP, EDOF lenses provide better intermediate and near vision performance in presbyopic participants without compromising distance vision. © 2016 American Academy of Optometry Source
Brien Holden Vision Institute | Date: 2015-02-24
Contact lenses are described with a corneal remodelling effect. This corneal remodelling effect is one or both of broad-area corneal remodelling and localised remodelling. The contact lenses may also have a refractive power. The refractive power may vary across the lens and for myopia may have increased power centrally. The increased power may be provided over a lens area that has increased thickness due to localised remodelling.
Brien Holden Vision Institute | Date: 2015-08-31
An optical processor is presented for applying optical processing to a light field passing through a predetermined imaging lens unit. The optical processor comprises a pattern in the form of spaced apart regions of different optical properties. The pattern is configured to define a phase coder, and a dispersion profile coder. The phase coder affects profiles of Through Focus Modulation Transfer Function (TFMTF) for different wavelength components of the light field in accordance with a predetermined profile of an extended depth of focusing to be obtained by the imaging lens unit. The dispersion profile coder is configured in accordance with the imaging lens unit and the predetermined profile of the extended depth of focusing to provide a predetermined overlapping between said TFMTF profiles within said predetermined profile of the extended depth of focusing.
Brien Holden Vision Institute | Date: 2014-02-13
Contact lenses and methods for designing and manufacturing contact lenses are disclosed. The contact lenses comprise a zone outside a central optic zone having a thickness profile with a varying thickness. The thickness profile provides rotational force to rotationally orient the contact lens when applied to a recipient eye. The thickness profile includes substantially curvilinear lines of constant thickness that extend generally horizontally across the lens. The curvilinear lines of substantially constant thickness may match the contact lines of the margins of at least one of the eyelids of the recipient.