International survey of rigid contact lens fitting

To determine the extent of rigid contact lens fitting worldwide and to characterize the associated demographics and fitting patterns. Survey forms were sent to contact lens fitters in up to 40 countries between January and March every year for five consecutive years (2007 to 2011). Practitioners were asked to record data relating to the first 10 contact lens fits or refits performed after receiving the survey form. Survey data collected between 1996 and 2011 were also analyzed to assess rigid lens fitting trends in seven nations during this period. Data were obtained for 12,230 rigid and 100,670 soft lens fits between 2007 and 2011. Overall, rigid lenses represented 10.8% of all contact lens fits, ranging from 0.2% in Lithuania to 37% in Malaysia. Compared with soft lens fits, rigid lens fits can be characterized as follows: older age (rigid, 37.3 ± 15.0 years; soft, 29.8 ± 12.4 years); fewer spherical and toric fits; more bifocal/multifocal fits; less frequent replacement (rigid, 7%; soft, 85%); and less part-time wear (rigid, 4%; soft, 10%). High-Dk (contact lens oxygen permeability) (36%) and mid-Dk (42%) materials are predominantly used for rigid lens fitting. Orthokeratology represents 11.5% of rigid contact lens fits. There has been a steady decline in rigid lens fitting between 1996 and 2011. Rigid contact lens prescribing is in decline but still represents approximately 10% of all contact lenses fitted worldwide. It is likely that rigid lenses will remain as a viable, albeit increasingly specialized, form of vision correction.

Contact lens prescribing in the Australian states and territories 2001

Background: This study was conducted to ascertain current preferences for contact lens prescribing in the Australian states and territories.

Methods: One thousand questionnaires were randomly distributed to proportionate samples of optometrists in each state of Australia. We requested details of the first 10 patients fitted with contact lenses after receipt of the questionnaire.

Results: One hundred and seventy-eight completed questionnaires were returned, detailing contact lens fits to 1,611 patients. The mean age of the patient group was 32.1 $pL 13.0 yrs (65 per cent female). For Australia as a whole: 53 per cent of patients were existing wearers, the remainder were new fits; 93 per cent of new fits were with soft lenses, of which seven per cent were for extended wear. Of the refits, 89 per cent were soft lenses and 18 per cent for extended wear. The lens material of first choice was mid-water-content (62 per cent of all soft lens fits). Only eight per cent of all soft fits were for lenses that were not replaced on a planned basis, with two weeks being the replacement interval of choice in all states and territories. The majority of rigid lenses were prescribed using mid-Dk materials (50 per cent). Analysis of solution prescribing indicates that multi-purpose products were the most common regimens for planned replacement soft lenses. The percentage of hydrogen peroxide prescribed increased as lens replacement became less frequent. By state or territory: practitioners in Tasmania prescribed more extended wear than those in any other state (p = 0.007) and practitioners in Queensland prescribed more daily disposable contact lenses than those in any other state (p = 0.009).

Conclusions: Non-planned replacement lenses are now rarely prescribed to patients. Extended-wear lenses and rigid lenses continue to be prescribed more to existing contact lens wearers than to new patients. The impact of soft multifocal lens designs on contact lens prescribing is very small, ranging from 2.6 per cent in Queensland to 4.7 per cent in Victoria, despite 20 per cent of patients being more than 45 years of age.

Contact lens prescribing in Canada 2011

The annual survey to collect data on the contact lens prescribing preferences of practitioners has continued for 12 years in Canada. Practitioners were surveyed for information on the first 10 patients they fitted with contact lenses immediately after receipt of said survey. A total of 121 completed surveys were returned, detailing contact lens fittings for 1,184 patients.

Of the patients fitted with contact lenses, the results indicated that the majority were prescribed soft lenses. The preferred modality was monthly planned replacement and over 67 per cent of the soft lens fits were made of silicone hydrogel materials. Of the rigid lens fits, the majority were prescribed for daily wear, as the overnight use of rigid lenses appears to be mainly for orthokeratology. Practitioners are recommending multipurpose solutions for the majority of their soft lens patients (85.6%).

Clinical performance of an innovative back surface multifocal contact lens in correcting presbyopia

Purpose: This prospective study was designed to subjectively and objectively evaluate the performance of an aspheric multifocal back surface rigid gas permeable (RGP) contact lens. The multifocal element of this lens design consisted of an aspheric optical zone that varied according to the patient's ametropia, corneal topography, and required reading addition.

Methods: We fit 28 presbyopic subjects with an aspheric multifocal back surface RGP contact lens (age range: 45 to 68 years). Reading additions ranged from +0.75 D to +2.50 D. Subjects were assessed initially and at 2, 6, and 12 weeks for ocular changes, visual performance, and subjective responses.

Results: We required 116 RGP lenses to achieve an acceptable fit and visual acuity in 28 subjects (55 eyes). At the final visit, the distance logMAR acuity with the multifocal contact lens (+0.12 +/-0.10) was not statistically different (t=-0.623, P= 0.5388) from spectacle acuity at the initial visit (+0.10 +/-0.12). The near logMAR acuity with the multifocal contact lens at the final visit (0.36 +/- 0.12) was not statistically different from that for near acuity with spectacles at the initial visit (0.33 +/- 0.13). No slit lamp signs worsened during the study. A reduction in myopia of 0.67 D was noted by the final visit. Spectacle blur was noted if the acuity at the initial refraction was compared to the acuity with the same refraction at the final visit (t= -3.287, P= 0.0028) but not when the refractive changes were incorporated (t= 1.058, P= 0.3127). All subjects rated the performance of the lenses very highly: comfort, 86%; distance acuity, 83%; near acuity, 73%; and stability of vision, 74%. Twenty-four subjects (86%) chose the multifocal contact lens as their preference.

Conclusion: We demonstrated that a multifocal design is able to provide acceptable distance and near correction for presbyopic patients. The aspheric geometry required can be optimized for a given patient by considering his/her degree of ametropia, as well as the corneal topography.

Trends in Australian contact lens prescribing during the first decade of the 21st century (2000–2009)

Purpose:  The aim was to document contact lens prescribing trends in Australia between 2000 and 2009.

Methods:  A survey of contact lens prescribing trends was conducted each year between 2000 and 2009. Australian optometrists were asked to provide information relating to 10 consecutive contact lens fittings between January and March each year.

Results:  Over the 10-year survey period, 1,462 practitioners returned survey forms representing a total of 13,721 contact lens fittings. The mean age (± SD) of lens wearers was 33.2 ± 13.6 years and 65 per cent were female. Between 2006 and 2009, rigid lens new fittings decreased from 18 to one per cent. Low water content lenses reduced from 11.5 to 3.2 per cent of soft lens fittings between 2000 and 2008. Between 2005 and 2009, toric lenses and multifocal lenses represented 26 and eight per cent, respectively, of all soft lenses fitted. Daily disposable, one- to two-week replacement and monthly replacement lenses accounted for 11.6, 30.0 and 46.5 per cent of all soft lens fittings over the survey period, respectively. The proportion of new soft fittings and refittings prescribed as extended wear has generally declined throughout the past decade. Multi-purpose lens care solutions dominate the market. Rigid lenses and monthly replacement soft lenses are predominantly worn on a full-time basis, whereas daily disposable soft lenses are mainly worn part-time.

Conclusions:  This survey indicates that technological advances, such as the development of new lens materials, manufacturing methods and lens designs, and the availability of various lens replacement options, have had a significant impact on the contact lens market during the first decade of the 21st Century.

Verification of the vertex powers of varifocal rigid contact lenses

 

Survey of contact lens prescribing to infants, children, and teenagers

Purpose. To determine the types of contact lenses prescribed for infants (aged 0 to 5 years), children (6 to 12 years), and teenagers (13 to 17 years) around the world.

Methods. Up to 1000 survey forms were sent to contact lens fitters in each of 38 countries between January and March every year for 5 consecutive years (2005 to 2009). Practitioners were asked to record data relating to the first 10 contact lens fits or refits performed after receiving the survey form.

Results. Data were received relating to 105,734 fits [137 infants, 1,672 children, 12,117 teenagers, and 91,808 adults (age ≥18 years)]. The proportion of minors (<18 year old) fitted varied considerably between nations, ranging from 25% in Iceland to 1% in China. Compared with other age groups, infants tend to be prescribed a higher proportion of rigid, soft toric, and extended wear lenses, predominantly as refits for full-time wear, and fewer daily disposable lenses. Children are fitted with the highest proportion of daily disposable lenses and have the highest rate of fits for part-time wear. Teenagers have a similar lens fitting profile to adults, with the main distinguishing characteristic being a higher proportion of new fits. Orthokeratology fits represented 28% of all contact lenses prescribed to minors.

Conclusions. Patterns of contact lens prescribing to infants and children are distinctly different to those of teenagers and adults in a number of respects. Clinicians can use the data presented here to compare their own patterns of contact lens prescribing to minors.

International contact lens prescribing

Survey results from six countries provide a snapshot of contact lens prescribing around the world.