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Azin Abazari, Harbans Dhadwal; Utility of Vision Index Pen in detecting early cataract and loss of accommodation. Invest. Ophthalmol. Vis. Sci. 2018;59(9):6016. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Prevention or delaying the onset of presbyopia and cataract formation remains a challenging problem. Detection of early changes in crystalline lens can be useful in screening the subjects who may benefit from early therapeutic interventions. The goal of our study was to establish the clinical utility of the Vision Index Pen (VIP), designed to measure in vivo dynamic light scattering from the crystalline lens, in detection of early cataract or loss of accommodation.
Volunteer human subjects in the age groups: 20-29, 30-39, 40-49, 50-59 and above 60 were consented to participate in this observational clinical study. All subject underwent detailed eye examination including measurement of near and distance visual acuity, the amplitude of accommodation, and slit lamp examination for grading of cataract. Subsequently, the VIP device was used to make five independent measurements of the intensity correlation of the backscattered light from the lens. Measurements were performed at a wavelength of 633 nm, using a 100 mW, semiconductor laser source focused in the center of the lens. The correlation data from the human lens was processed to extract a vision index vector, which expresses the presence of the a-crystalline aggregates.
The repeatability and reproducibility of the VIP device, assessed using NIST certified 22 nm standard particles at 1% solids concentration, was found to be 1% and 2% respectively. Our early data suggest that faster correlation times are consistent with smaller sizes of the scattering system, while longer times are associated with the presence of aggregated clusters. In our study, faster correlation time was seen in younger patients with higher amplitude of accommodation and without cataract.
Results from this ongoing observational clinical trial show that in vivo dynamic light scattering measurement is helpful in early detection of loss of accommodation and cataract. Therefore, VIP can be a valuable tool in identifying patients who can potentially benefit from early interventions, such as administration of the preventive therapeutic agents, to slow the aging process of the lens.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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