 |
|
Custom-Made Presbyopia Contact Lenses?
 Soft contact lenses represent over 90% of new fittings, and presbyopic correction is an increasingly important part of that. While monovision remains a significant part of this segment, generally its role has decreased over the years in favor of an increasingly optimized and diverse portfolio of soft multifocal contact lenses. But still, presbyopic contact lens correction seems to be in its infancy. Can we do better? At one hand, knowledge has increased over the last few years regarding the optical characteristics and visual performance of multifocal contact lenses, allowing us to make more informed decisions for our presbyopic patients. Now the relationship among the optimal power distribution across the optic zone, the pupil size, the inherent ocular aberrational and residual accommodation, and the visual benefit achievable is much clearer than before. Furthermore, recent optimization of the material properties and the manufacturing processes is a crucial step to ensure a more precise match between the predicted performance during the lens design phase and the actual behavior on the eye. Advances in presbyopic contact lens designs are increasing our understanding of the interactions of the ocular and lens characteristics. While improving the overall performance of the disposable lens designs, this opens a window of opportunity for custom-made contact lenses optimized for the patient's ocular characteristics in terms of corneal topography, ocular low- and high-order aberrations, pupil size dynamics and residual accommodation. These developments, combined with the current demographic trends in most developed countries, will fuel the future of contact lenses as a whole segment. In other words: the answer to the question raised in the title is "Yes, please." A large group of emerging presbyopes are waiting for better solutions; they will be forever grateful for the options provided in the (near) future.
Jose Manuel Gonzalez-Meijome OD, PhD
Associate Professor Clinical & Experimental Optometry Research Lab
University of Minho - Braga (Portugal)
|
 
Soft Lenses for Myopia Control
Radial Refractive Gradient Lenses & Customizing Myopia Control Lenses
A paper by Jaime Pauné in BioMed Research International, based on his work for his recently completed PhD, aimed to evaluate the degree of axial elongation with specially designed, soft radial refractive gradient lenses. The results were compared to orthokeratology and to single-vision spectacle lenses for a period of 1 year before treatment and for 2 years after treatment. Conclusion: the specially designed soft lenses for myopia control significantly decreased the axial elongation of the eye compared to the single-vision spectacle control group. The soft lens was similarly effective to orthokeratology in preventing myopia progression in myopic children and adolescents. A column on the myopiaprofile.com website looks at 'Customising the perfect myopia control contact lens'. The column states that '...we will likely have to customize lenses for myopia control.' Myopia control is complex, the paper states, but '...for myopia control to be successful, it needs to be performed with a customized lens geared toward the individual anatomical features and refractive profile of the myope.' The column continues to state the importance of being able to control the front and the back surface of soft lenses: "In Dutch we have a saying 'In Optima Forma,' which means 'to be perfect' or 'at its best' form or shape. For myopia control to be effective, it needs to be 'In Optica Forma'. The optics should be right, and the form or shape should be right too. Most likely, optimized front surfaces (different optical profiles) and back surfaces (to align the lens best with the ocular surface and to potentially prevent decentration) would provide the best results. And that would actually be totally in sync with the current 3D-printing era we live in... The future of our contact lens practices may be much more 'customized' than currently is the case."
|
White-to-White Corneal Diameter Measurement
Corneal Diameter, Horizontal Visible Iris Diameter, Topographer, OCT
At the recent Global Specialty Lens Symposium in Las Vegas, Chad Rosen of the Michigan College of Optometry at Ferris State University (US) rose the point of 'The Role of horizontal visible iris diameter (HVID) in Determining Proper SCL Fitting' in a session on 'Controversies in Soft Lens Fitting.' Many in the past have iterated that diameter selection would be a much better predictor of soft lens fit on-eye than central keratometry measures and BCR choice. One aspect of this is that measuring corneal diameter is not as straightforward is it may look. Typically, corneal topographers use 'white-to-white' (WTW) measurements to distinguish the cornea from the sclera. A paper in Contact Lens & Anterior Eye compares WTW measurements obtained using low optical coherence reflectometry and by corneal topography. In conclusion, generally good agreement was found between the Lenstar and Tomey RC-5000, Topolyzer for WTW measurements. In clinical practice, WTW measurements obtained by Lenstar and Tomey RC-5000, Topolyzer can be used interchangeably, the paper states. |
An Open Mind: Soft Lenses for Keratoconus
Intracorneal Ring Segments, Custom-Made Lenses, Visual Acuity
|
Diameter, Sagittal depth, Base curve, Surface Deposition, Contact Angle
Investigators at the University of Waterloo (CA) looked at the 'Impact of Cosmetics on the Physical Dimension and Optical Performance of Silicone Hydrogel Contact Lenses.' Makeup removers had the greatest impact on diameter, sagittal depth, and base curve, resulting in changes of up to 0.5, 0.15, and 0.77 mm, respectively. The hand creams and mascaras had little impact on these parameters; however, differences were observed between lens types. Optical performance was reduced with all mascaras, and a decrease of greater than 2 units on a 0 to 10 scale was seen for 5 lens types exposed to waterproof mascara. Lens cleaning resulted in some recovery of the lens parameters, and efficiency varied between cosmetics. The same group also looked into the 'Impact of Cosmetics on the Surface Properties of Silicone Hydrogel Contact Lenses.' The visible surface deposition, described as pixel brightness, was significantly higher for mascara-coated lenses compared with the other cosmetic products. The peroxide-based lens care solution removed most deposits from the non-waterproof mascara for four lens types, whereas deposits remained relatively unchanged for one waterproof mascara. Hand creams and makeup remover had minimal impact on pixel brightness. Changes in contact angle measurements after cosmetic application were highly lens dependent. Hand creams caused primarily a decrease in contact angle for 5 of the 7 lens types, whereas 1 of the waterproof mascaras caused a significant increase of 30º to 50° for 3 lens types.
|
Bandage Lens in Bleb Leak Following Trabeculectomy
Glaucoma, Anterior Chamber Depth, Intraocular Pressure, Bandage Lens
Between October 2011 and April 2013, 11 patients with early bleb leak following fornix-based trabeculectomy were instructed to continuously wear a soft bandage contact lens 14 mm in diameter for 1-2 weeks. Bleb leaks were observed at 2-8 days after surgery on average. The visual acuity did not significantly differ before and after contact lens wear. The IOP at 3 months after lens wear did not significantly differ from that measured at lens removal. At 1 day after lens wear, 6 cases had deeper anterior chambers. All patients presented with a significantly deepened anterior chamber at 3 days after lens wear and were restored to the preoperative conditions. The bleb leakage was successfully treated at 7 days after lens removal in 10 patients, while 1 patient had to wear the contact lens for another 7 days for full healing of the bleb leak. No ocular infection was noted throughout the management. In conclusion, the investigators state that a soft bandage contact lens of 14 mm diameter is a safe and efficacious therapy for an early bleb leak following fornix-based trabeculectomy.
|
Individual Lens Fit in Daily Disposable Lenses
Silicone Hydrogel, Daily Disposable, Ocular Comfort, Physiology, Wettability
The influence of end-of-day silicone hydrogel daily disposable contact lens fit on ocular comfort, physiology and lens wettability was the topic of a study by Wolffsohn et al. Thirty-nine subjects were randomised to wear each of 3 silicone-hydrogel daily-disposable contact lenses (narafilcon A, delefilcon A and filcon II 3) bilaterally for one week. Lens fit was assessed objectively using a digital video slit lamp at 8, 12 and 16 hours after lens insertion. Lens fit assessments were not different between brands, with the exception of the movement at blink in which narafilcon A was more mobile. Overall, lag reduced but push-up speed increased from 8 to 12 hours, but remained stable from 12 to 16 hours. Movement-on-blink was unaffected by wear time. A more mobile lens fit with one brand did not indicate that that person would have a more mobile fit with another brand. Consequently, substitution of a different lens brand with similar parameters will not necessarily provide comparable lens fit, according to the investigators.
|
|
 |
This Newletter is Kindly supported by: 
|
| |
|
|
|
|
