Progressive addition lenses (PALs) have some particular optical characteristics that derive from the corridor of the progressive surface along the meridian of the lens. In this paper, I will talk about the basic specifications and optical characteristics of these lenses. Advances in free-form cutting machines have enabled the fast fabrication of complex surfaces to high precision; consequently, this has led to the development of some new PAL. These are customized lenses whose creation takes into consideration various wearer conditions. Lens design is optimized to provide the best performance for the individual wearer. Some PAL may therefore have lens power information that differs from the usual.
Progressive power glasses should be selected foremost in the correction of presbyopia; however, many Japanese feel negative toward them. This is because there are problems in those who wear, prescribe and manufacture glasses: in wearers, it is a lack of understanding; in technicians who prescribe and manufacture glasses, it is a lack of technology. Even if progressive power glasses are used, there are numerous instances in which the power for reading becomes inappropriate owing to inaccurate optometry of the power for distance. In addition, faulty frame adjustment is all too frequent. It is also problematic that individuals who do not know the basics of glass manufacture are involved in optometry. It is absolutely necessary to restructure the Japanese optometric system itself, in order to realize proper evaluation of progressive power glasses.
In order to comfortably use glasses with the progressive addition lenses (PALs), it is necessary to familiarize that patient with PALs’ characteristic aberrations. If the additional lens power is smaller, the PAL aberration is less. Commencement of PAL use in initial presbyopia is recommended. If, unfortunately, the patient has passed through the initial presbyopic period without using PAL, the additional lens power of the PAL first prescribed should be set lower than usual; the power should be amended after the patient becomes familiar with PAL use, and so becomes able to use adequately powered PAL with no problems. I explain how to prescribe glasses with PALs that provides comfortable vision.
Purpose: We evaluated the clinical reproducibility of interobserver and intraobserver data obtained using the newly developed anterior segment optical coherence tomography (OCT) VisanteTM (Carl Zeiss Meditec). We also considered the differences between the two measurement modes.
Methods: Observed in this study were 21 eyes of 11 subjects (mean age: 31.2±8.2 years) with no ocular disease other than refractive error. The central corneal thickness (CCT) and the anterior chamber depth (ACD) of each subject was measured by two examiners, five times each. The data from CCT measurements taken by automated and manual modes, the pachymetry scan and the anterior segment scan using a caliper were also compared.
Results: The average CCT was 535.6±2.0μm (observer A) and 533.7±2.4μm (observer B) in automated mode, and 556.1±0.3μm (observer A) and 549.5±0.2μm (observer B) in manual mode. The average ACD was 3.728±0.017mm (observer A) and 3.729±0.022mm (observer B). The maximum difference between interobserver data in automated mode was 8.8μm; that in manual mode was 50.0μm (CCT) and 70μm (ACD). There was no significant difference in interobserver data between automated and manual modes.
Conclusions: The reproducibility of VisanteTM is highly appreciated; it is a useful tool for various anterior segment analyses.