reports on a practitioner and consumer study that examined experiences with presbyopia correction
Worldwide, eye care professionals (ECPs) are seeing a growing number of patients in their early to mid-40s and older who would benefit from presbyopic vision correction; patients who need simultaneous correction for near, intermediate, and distance vision. One challenge in this patient population is the contact lens dropout rate. There is increased dropout from contact lenses after 45 years of age, despite a growing vision-corrected population and increasing interest in contact lenses (Figure 1).1 As the presbyopic population increases, so too does the need for ECPs to understand advances in contact lens optics and their patients’ ever-changing vision needs.
Recently, a study was completed in the US and France to examine ECP and patient experiences with presbyopia to better understand patients’ vision needs.2 The study employed a web survey that was administered to 404 US and 301 French patients. The survey captured patient demographics and asked about lens use satisfaction, the frequency and impact of symptoms experienced with contact lens use, and an assessment of the patient’s daily vision needs. A separate web survey was also administered to 75 US ECPs, and 75 French ECPs that asked each ECP to discuss the challenges and success rates of fitting presbyopic patients.
Life activities and vision needs
When asked to rate their overall satisfaction by lens attributes, the primary area of dissatisfaction for multifocal and monovision wearers was near vision. The survey also asked about the ‘real-world’ vision needs for presbyopes. Although all vision categories (near, intermediate, and distance vision) were listed as visual priorities while working, near vision caused the most visual issues for all lens wearers at work. Forty-seven per cent of US lens wearers and 40 per cent of French contact lens wearers reported it was hardest to obtain satisfactory near and intermediate vision (Figure 2). This is not surprising given that many contact lens wearers spend the majority of their work day using a computer (Figure 3).3
ECPs agree that correcting distance vision is the least challenging in both the US and France. However, correcting near (US) or mid-range (France) vision was listed as the greatest challenge (Figure 4). When ECPs were asked about the number of visits it takes to successfully fit a presbyopic patient, US and French survey responses indicated an average of 2.6 visits to successfully fit a patient with presbyopia. It was estimated that for 51 per cent of US ECPs and 45 per cent of French ECPs, it took three or more visits to successfully fit presbyopic patients with contact lenses. This means that on average, four in 10 patients do not have a successful fitting in the first or second visit. Both US and French ECPs estimated that approximately three in 10 presbyopes are never successfully fitted with lenses. This process can be frustrating for patients and ECPs alike.
Comparing lens designs
While the above studies did not examine fitting success rates of specific lens brands, an earlier study evaluated the power profiles of two of the most popular brands.4,5 That study examined similarities and differences between designs/wavefront measurements using a new generation of Hartmann-Shack instruments. The following lenses were compared: PureVision MF low and high add lenses, and the Air Optix Aqua MF low, medium, and high add lenses. Measurements were also taken on PureVision and Air Optix Aqua single-vision sphere lenses. Three separate -3.00D lenses were measured for each of the multifocal or single vision sphere lens designs from the centre out to a 3mm radial distance. The median power of the three measurements was then plotted to create power profiles that could help explain on-eye performance of these lenses (Figures 5 and 6).
Both PureVision MF and Air Optix Aqua MF lenses use aspheric optical designs (negative spherical aberration) to create a centre-near add. However, the PureVision MF has two different add power designs, while Air Optix Aqua uses three different add power designs. The question the study asked was, does the additional add power design provide additional benefit?
The power profiles for the PureVision MF lenses demonstrated two distinct, differentiable power profiles (Figure 5). The PureVision MF low add lens demonstrated more than twice the add power provided by the Air Optix Aqua low add MF lens: an estimated add of +0.59D for the PureVision MF lenses compared to an estimated add of only +0.25D for the Air Optix Aqua MF lenses. The PureVision MF high add lens demonstrated a greater amount of add than either the Air Optix Aqua medium or high add lenses: an estimated add of +1.84D compared to +1.31D and +1.41D for the Air Optix Aqua MF medium and high add lenses, respectively. Figure 6 shows the power profiles for the three Air Optix Aqua multifocal designs and the Air Optix single-vision lens. Because of the similar power profile between the Air Optix Aqua medium and high add lenses, ECPs may find it difficult to discriminate between the add powers clinically, and may struggle to find an adequate solution when the patient’s need for greater add power develops throughout the stages of presbyopia. PureVision MF provides more add power to help address the needs of the presbyopic wearer.
Conclusion
The presbyopic population is challenging to fit due to the differing distance, intermediate, and near vision needs of this patient population. Near and intermediate vision continue to be the greatest fitting challenge for ECPs and the greatest area of disappointment for patients in a world of increased near and intermediate visual demands, especially from numerous hours spent on computers and smart phones each day. The fitting process can be frustrating for patients and ECPs alike when you consider it takes an average of 2.6 fittings to successfully fit a patient with contact lenses and that approximately three in 10 presbyopes are never successfully fitted for lenses. Power profile mapping can help provide insight into fitting aspheric multifocal contact lenses. The power profiles of the three Air Optix Aqua multifocal contact lenses showed that there are effectively only two distinct add powers whereas measurements of the two PureVision MF lenses confirmed two distinct add powers. PureVision MF provides more add power to help address the needs of the presbyopic wearer. Knowledge of the lens power profile can guide the ECP toward selecting the best lens design for the patient.
References
1 Source: Multi-sponsor Surveys’ 2010 WW Consumer Contact Lens Market Study Interviews conducted in Western Europe, Sweden, Russia, China, India, Hong Kong, Taiwan, Singapore, South Korea, Thailand, Malaysia, Australia and the US.
2 Market research: Kadence International. July 2012.
3 Exploring blurry, changing or fluctuating vision associated with contact lens wear. Kadence International. January 2012.
4 Vogt, AKS, et al, Using power profiles to evaluate aspheric lenses. CL Spectrum, 2011 (January).
5 Vogt, AKS, et al. Distribution of power. Optician, 02.07.10; Vol 240, No 6259, pp 16-17.
? Cheryl Donnelly is director of medical affairs, B+L, Europe, Middle East and Africa