New orthokeratology lens design for presbyopia
Document typeMaster thesis
Rights accessOpen Access
Presbyopia is defined as an impairment in near vision, limitating the residual accommodation, hence losing the ability to focus on neal objects. Throughout the world, uncorrected presbyopia causes common, avoidable vision impairment. When the symptoms are established, on a 55 to 60-year-old average, artificial assistance for comfortable close-up tasks is needed. The aim of the study is to investigate the efficacy of a new presbyopic orthokeratology lens design, on a 4-week perios of presbyopic orthokeratology overnight wear. Eighteen presbyopic new orthokeratology wearers, were reviwed. Only seven participants contributed to complete data. A double reservoir lens for presbyopia design with two with different back optical zone diameters was evaluated. Uncorrected distance and near visual acuity, subjective refraction, contrast sensitivity, defocus curve, corneal topography, corneal aberrations and anterior segment health examination were measured at baseline, and compared after a 4-week overnight wear, with designs of 1.9 and 3.0mm back optical zone diameters. Both double reservoir lenses for presbyopia, revealed statistically significant changes. The 1.9mm lens almost corrected distance ametropia, while 3.0mm lens induced a slight myopia, in contraposition, 3.0mm corrected near ametropia by decreasing a 50.55% of the near addition on average. Binocular distance vision remained equal, but uncorrected visual acuities improved after both lenses were used. Induced corneal aberrometries lead to a contrast sensitivity descrease in medium and high frequencies. As a conclusion we can say that double reservoir lenses for presbyopia provide functional near vision by inducing a “center near” myopic shift. Eventhought corneal aberrations were induced, it did not alter binocular visual acuities.
DegreeMÀSTER UNIVERSITARI EN OPTOMETRIA I CIÈNCIES DE LA VISIÓ (Pla 2012)