The Effect of Fractal Contact Lenses on Peripheral Refraction in Myopic Model Eyes

Abstract

Visual acuity and contrast sensitivity with iPad 2 2. Structured abstract. PurposeTo present two iPad applications (apps) for measuring Visual Acuity (VA) and Contrast Sensitivity Function (CSF) and to assess reliability and agreement with a commercial screening device. MethodsForty-five healthy subjects with monocular corrected visual acuities better than 0.2 logMAR participated in the agreement study of VA and CSF with iPad and Optec 6500. Results MD of VA was 0.06 logMAR better with AmblyopiaVA than with ETDRS (p<0.001) andLoAs were around ±0.2 logMAR. Test-retest reliability was better with AmblyopiaVA (r=0.15) with no statistically significant differences between days (p>0.05). A good agreement with no significant differences (p>0.05) was obtained with ClinicCSF and FACT. MDs were below 0.05 log units at all the spatial frequencies but non-constant LoAs were manifested at 3.6 and 18 cpd. Null hypotheses of same medians along days were accepted for both tests (p>0.05) but reliabilities were poorer with the increment of the spatial frequency. ConclusionsThe iPad tests showed a good agreement with conventional tests and may be a convenient and faster alternative to some existing commercial screening devices. On the other hand future improvements in test-retest reliabilities should be done for the screening of CSF.

Relative Peripheral Myopia Induced by Fractal Contact Lenses

“…In our design, this limitation could be easily solved since the treatment power this is a free parameter that affects the peripheral refractive error without compromising the central vision, at least for pupil diameters lower than 4.0 mm. 10 For the nacked eye, we found that corneal asphericity along temporal and nasal semichords in the horizontal meridian was negatively correlated with the M component; but only for temporal cornea and nasal retina whereas for J45 and J0 the negative correlations where found between nasal cornea and temporal retina ( Table 1). This is also in agreement with theoretical models, which assert that the more positive is Q, the more myopic is the peripheral refraction induced for M and J0.…”

“…In most of the clinical studies, the study of the effect of the proposed solutions was restricted to the analysis of the RPRE, measured in terms of vector components M, J0 and J45 along the horizontal meridian, 3,6 and only few include the vertical and oblique meridians. [19][20][21] In this work we have presented the first clinical study in which the ability of a new design of CLs [10] to create a RPRE in the whole 2D visual field has been demonstrated. Taking into account that, on the one hand, the mean power at the treatment zones (+1.32 D) of the manufactured lenses was lower than the theoretical labelled power (+2.00 D); and, on the other hand, that lens prototypes were decentered during the RPRE measurements an excellent agreement between the theoretical and experimental results has been obtained (see Fig.5A).…”

“…FCLs are multizone bifocals with a special design as described in Ref. [10]. The profile of the lenses are shown in Fig.…”

“…Several methods have been proposed to slow myopia progression; among them, non-pharmacological treatments, like orthokeratology and peripheral defocus modifying contact lenses (CLs) achieved very good outcomes, which has been attributed to the induction of a myopic Relative Peripheral Refractive Error (RPRE), although the optical mechanisms for myopia development still remain controversial. [1][2][3][4][5][6][7] Different designs of multifocal CLs were proposed to this aim, 6,[8][9][10] and consequently, the amount and extension of the induced RPRE vary among lenses. Since the ocular growth during the emmetropization process might depend on the stimulated retinal areas, 11 it is expected that different designs will provide different results.…”

“…In particular, it is likely that the astigmatic component of the RPRE plays a role in the myopia development in humans, as it has been demonstrated it plays in the emmetropization in monkeys 12 and chicks. [12][13] In a previous paper, 10 we have proposed a new design of CLs for myopia control, named Fractal Contact Lenses (FCLs). The potentiality of FCLs to produce a myopic RPRE was demonstrated by ray tracing methods in model eyes.…”