Field restriction and vignetting in contact lenses with opaque peripheries

Carkeet, Andrew

doi:10.1111/j.1444-0938.1998.tb06773.x

Cited by 17 publications

(20 citation statements)

References 10 publications

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“…They confirm that, although annular KAMRA‐type stops introduce variations in illuminance across the fundus, they have little effect on the visual field. This accords with the earlier clinical findings and differs from the field restrictions introduced by devices with simple circular apertures . Although presbyopes are likely to have smaller pupils, which will produce greater local variations in retinal illuminance ( Figure ), any practical effect will be limited since the inlay is normally implanted in only one eye and may not affect the binocular visual field.…”

Section: Discussionsupporting

confidence: 83%

“…These results are broadly in agreement with those of Langenbucher et al for the KAMRA inlay, which are expressed in terms of relative illumination on the retina. Similarly the field limits with the circular contact lens apertures are similar to those found by Carkeet …”

Section: Methodssupporting

confidence: 82%

“…Moreover, significant field loss in the midperiphery has also been found in studies with patients wearing coloured contact lenses or annular contact lenses with a clear pupil and a coloured portion covering the iris . In the case of small‐pupil contact lenses, Carkeet has shown that the limits to the unobstructed field and to the field boundary of the absolute field depend upon the diameters of both the contact lens pupil and the natural pupil, although he did not explore the variation in retinal illuminance across the field in detail.…”

Section: Introductionmentioning

confidence: 99%

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Do small‐aperture presbyopic corrections influence the visual field?

Atchison

Blazaki

Suheimat

et al. 2015

Ophthalmic Physiologic Optic

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Purpose: To explore the effect of small-aperture optics, designed to aid presby-opes by increasing ocular depth-of-focus, on measurements of the visual field. Methods: Simple theoretical and ray-tracing models were used to predict the impact of different designs of small-aperture contact lenses or corneal inlays on the proportion of light passing through natural pupils of various diameters as a function of the direction in the visual field. The left eyes of five healthy volunteers were tested using three afocal, hand-painted opaque soft contact lenses (www.davidthomas.com). Two were opaque over a 10 mm diameter but had central clear circular apertures of 1.5 and 3.0 mm in diameter. The third had an annular opaque zone with inner and outer diameters of 1.5 and 4.0 mm, approximately simulating the geometry of the KAMRA inlay (www.acufocus.com). A fourth, clear lens was used for comparison purposes. Visual fields along the horizontal meridian were evaluated up to 50° eccentricity with static automated perimetry (Medmont M700, stimulus Goldmann-size III; www.medmont.com). Results: According to ray-tracing, the two lenses with the circular apertures were expected to reduce the relative transmittance of the pupil to zero at specific field angles (around 60° for the conditions of the experimental measurements). In contrast , the annular stop had no effect on the absolute field but relative transmit-tance was reduced over the central area of the field, the exact effects depending upon the natural pupil diameter. Experimental results broadly agreed with these theoretical expectations. With the 1.5 and 3.0 mm pupils, only minor losses in sensitivity (around 2 dB) in comparison with the clear-lens case occurred across the central 10° radius of field. Beyond this angle, sensitivity losses increased, to reach about 7 dB at the edge of the measured field (50°). The field results with the annular stop showed at most only a slight loss in sensitivity (≤3 dB) across the measured field. Conclusion: The present theoretical and experimental results support earlier clinical findings that KAMRA-type annular stops, unlike circular artificial pupils, have only minor effects on measurements of the visual field.

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Section: Discussionsupporting

confidence: 83%

Section: Methodssupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Do small‐aperture presbyopic corrections influence the visual field?

Atchison

Blazaki

Suheimat

et al. 2015

Ophthalmic Physiologic Optic

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“…First, relative peripheral hyperopia was optically imposed on both eyes of 8 infant monkeys by securing −3.0 D spectacle lenses that had 6 mm circular apertures that were centered on each eye’s entrance pupil (-3D-aperture group)(See Smith and Hung (1999) for details of our helmet rearing procedures.). As discussed by Carkeet (1998) (Carkeet, 1998), to determine the extent of the visual field affected by a lens aperture it is necessary to take into account interactions between the eye’s pupil and the lens aperture (see Figure 1). Our helmets held the lenses at a 14 mm vertex distance so ignoring the prismatic effects of the lens and assuming an entrance pupil diameter of 3.0 mm and an anterior chamber depth of 2.58 mm, the resulting “unrestricted” field of view through the 6 mm apertures was 10.3 deg (i.e., all the rays that formed the retinal images within the central 10.3 deg passed through the lens aperture and were unaffected by the power of the treatment lens)(dotted lines in Figure 1).…”

Section: Methodsmentioning

confidence: 99%

Relative peripheral hyperopic defocus alters central refractive development in infant monkeys

2009

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Understanding the role of peripheral defocus on central refractive development is critical because refractive errors can vary significantly with eccentricity and peripheral refractions have been implicated in the genesis of central refractive errors in humans. Two rearing strategies were used to determine whether peripheral hyperopia alters central refractive development in rhesus monkeys. In intact eyes, lens-induced relative peripheral hyperopia produced central axial myopia. Moreover, eliminating the fovea by laser photoablation did not prevent compensating myopic changes in response to optically imposed hyperopia. These results show that peripheral refractive errors can have a substantial impact on central refractive development in primates.

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“…Moreover, tinted lenses may hamper night vision and reduce contrast sensitivity [9,10]. The color pigments used in these lenses can also induce allergic reactions or toxic keratopathy and render roughness to the lens surface, thereby adding trauma to the corneal epithelium [11].…”

Section: Discussionmentioning

confidence: 99%

Pigment Deposition of Cosmetic Contact Lenses on the Cornea after Intense Pulsed-Light Treatment

Hong

Lee

Lim

2010

Korean J Ophthalmol

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We report a case of corneal deposition of pigments from cosmetic contact lenses after intense pulsed-light (IPL) therapy. A 30-year-old female visited our outpatient clinic with ocular pain and epiphora in both eyes; these symptoms developed soon after she had undergone facial IPL treatment. She was wearing cosmetic contact lenses throughout the IPL procedure. At presentation, her uncorrected visual acuity was 2/20 in both eyes, and the slit-lamp examination revealed deposition of the color pigment of the cosmetic contact lens onto the corneal epithelium. We scraped the corneal epithelium along with the deposited pigments using a no. 15 blade; seven days after the procedure, the corneal epithelium had healed without any complications. This case highlights the importance of considering the possibility of ocular complications during IPL treatment, particularly in individuals using contact lenses. To prevent ocular damage, IPL procedures should be performed only after removing the lenses and applying eyeshields.

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Field restriction and vignetting in contact lenses with opaque peripheries

Cited by 17 publications

References 10 publications

Do small‐aperture presbyopic corrections influence the visual field?

Do small‐aperture presbyopic corrections influence the visual field?

Relative peripheral hyperopic defocus alters central refractive development in infant monkeys

Pigment Deposition of Cosmetic Contact Lenses on the Cornea after Intense Pulsed-Light Treatment

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