The effects of light scatter when using a photochromic vs. non-photochromic contact lens

The Effect of Photochromic Contact Lenses on Pupil Size

Objectives

Photochromic contact lenses (PCL) are designed to increase the comfort of patients, in bright light conditions. The aim of the study was to evaluate the effect of PCL on pupil size.

Methods

The study was conducted with 30 patients who were admitted to the contact lens department. Automated pupilography images of the right eyes of patients were obtained without contact lenses (group 1) in scotopic (S: 0.4 lux), mesopic (M: 4.0 lux), and photopic (p=40 lux) conditions. The procedures were repeated with silicone hydrogel contact lenses (Group 2) and with silicon hydrogel PCL (group 3).

Results

Mean age was 23.87±3.27 (17-30) years and male/female ratio was 10/20. The mean spheric equivalent of their right eyes was -3.60±1.73 (-0.50--7.50). Pupil diameters of Group 3, under scotopic conditions, were larger than Group 1 and 2 (p=0.001, p=0.044). There was no difference between groups under mesotopic and photopic conditions. Pupil diameters at the different illumination levels were similar regarding gender.

Conclusion

Similarity in mesotopic and photopic pupil sizes compared to all groups may be a result of insignificant pupil changes of photochromic lenses in indoor conditions or insufficient time for lens activation.

TFOS Lifestyle: Impact of contact lenses on the ocular surface

Several lifestyle choices made by contact lens wearers can have adverse consequences on ocular health. These include being non-adherent to contact lens care, sleeping in lenses, ill-advised purchasing options, not seeing an eyecare professional for regular aftercare visits, wearing lenses when feeling unwell, wearing lenses too soon after various forms of ophthalmic surgery, and wearing lenses when engaged in risky behaviors (e.g., when using tobacco, alcohol or recreational drugs). Those with a pre-existing compromised ocular surface may find that contact lens wear exacerbates ocular disease morbidity. Conversely, contact lenses may have various therapeutic benefits. The coronavirus disease-2019 (COVID-19) pandemic impinged upon the lifestyle of contact lens wearers, introducing challenges such as mask-associated dry eye, contact lens discomfort with increased use of digital devices, inadvertent exposure to hand sanitizers, and reduced use of lenses. Wearing contact lenses in challenging environments, such as in the presence of dust and noxious chemicals, or where there is the possibility of ocular trauma (e.g., sport or working with tools) can be problematic, although in some instances lenses can be protective. Contact lenses can be worn for sport, theatre, at high altitude, driving at night, in the military and in space, and special considerations are required when prescribing in such situations to ensure successful outcomes. A systematic review and meta-analysis, incorporated within the review, identified that the influence of lifestyle factors on soft contact lens dropout remains poorly understood, and is an area in need of further research. Overall, this report investigated lifestyle-related choices made by clinicians and contact lens wearers and discovered that when appropriate lifestyle choices are made, contact lens wear can enhance the quality of life of wearers.

Unexpected vision performance with photochromic contact lenses in normal and low light conditions: An analysis of two randomized trials

PURPOSE

Evaluate the performance of a photochromic contact lens in various lighting conditions throughout the day, including those indoor and outdoor environments where the photochromic contact lens is in a less active or inactive state.

METHODS

Data from two clinical trials of a photochromic contact lens were analyzed to evaluate its performance in various light environments. Both studies involved a photochromic test lens (ACUVUE® OASYS with Transitions™ Light Intelligent Technology™) and a similar non-photochromic control lens (ACUVUE® OASYS 2-week with HYDRACLEAR® PLUS). The studies were both multi-visit, multi-site, 2-treatment by 3-period randomized crossover (i.e., Test/Control/Control or Control/Test/Test) dispensing studies, with follow-up visits after each 2-week dispensing period.

RESULTS

A total of 250 subjects were dispensed lenses across both studies, of which 237 total subjects completed. In situations where exposure to an activating light source is common (e.g., outdoors), the Test lens was preferred nearly 6:1 over the control lens. In situations where exposure to an activating light source is less common - indoors, driving at night, using digital devices -, the Test lens was still preferred over the control lens by margins of 4:1, nearly 4:1, and over 3:1 respectively. The Test lens was superior with respect to quality of vision, ability to see comfortably, clarity of vision, reduction of squinting while using computers and reduction of bright light while driving at night.

CONCLUSION

The photochromic test contact lens was rated superior to a non-photochromic control lens in environmental situations where the lens is in a less active or inactive state.

The Influence of HEV-Filtering Contact Lenses on Behavioral Indices of Glare

OBJECTIVES

We assessed the effects of a HEV-filtering contact lens on positive dysphotopsia (halos and starbursts) and a behavioral index of scatter measured using two-point light thresholds. These effects were assessed by direct comparison to a clear (i.e., non-HEV filtering) contact lens tested in the fellow eye.

METHODS

Sixty-one subjects were randomized and fit with study lenses and 58 subjects completed the study. A double-masked contralateral design was used. Subjects were randomized to test lens-OD, control lens-OS, or vice versa. Participants were exposed to a point source of broadband simulated sunlight (a 403-nm condition was also tested) that created the appearance of halos/starbursts. The degree of dysphotopsia was measured as the diameter of broadband and violet-induced halos, and broadband light-induced starbursts. Two-point thresholds were assessed as the minimum resolvable distance between two pinpoints of light.

RESULTS

The HEV-filtering lens was statistically superior ( P <0.0001) to the clear lens in all the conditions tested. The HEV-filtering lens significantly reduced halo diameter by 30%, starburst diameter by 23%, and resolvable distance in the two-point condition by 18% (white) and 30% (violet).

CONCLUSIONS

HEV-filtering contact lenses can reduce some deleterious effects of bright broadband light by decreasing light scatter, halos, and starbursts.

Effect of Photochromic Contact Lens Wear on Indoor Visual Performance and Patient Satisfaction

INTRODUCTION

To quantitatively assess visual performance and patient satisfaction during photochromic contact lens (CL) wear in an indoor environment.

METHODS

This observational study comprised 82 eyes of 41 healthy subjects (mean age ± standard deviation, 21.7 ± 0.7 years) who had no ophthalmic diseases except for refractive errors at Kitasato University in 2021. We prospectively compared visual acuity, kinetic visual acuity, functional (time-dependent) visual acuity, the maintaining rate of visual acuity, the response time, contrast sensitivity function, higher-order aberrations, and patient satisfaction score for overall vision in such subjects during photochromic and non-photochromic CL wear in such an environment.

RESULTS

The kinetic visual acuity at 30 km/h was 0.32 ± 0.21 and 0.41 ± 0.24 in the photochromic and non-photochromic CL groups, respectively (p = 0.008). The kinetic visual acuity at 60 km/h was 0.32 ± 0.21 and 0.41 ± 0.24, respectively (p = 0.034). The functional visual acuity was 0.00 ± 0.21 and 0.05 ± 0.25, respectively (p = 0.030). The average response time was 1.19 ± 0.15 s and 1.23 ± 0.15 s, respectively (p = 0.029). The patient satisfaction score for overall visual performance was 4.22 ± 0.11 and 3.59 ± 0.68, respectively (p < 0.001). Otherwise, we found no significant differences in visual acuity, the maintaining rate, higher-order aberrations, or contrast sensitivity function (p = 0.116, p = 0.053, p = 0.371, or p = 0.943). We found no apparent complications such as ocular discomfort, superficial punctate keratitis, conjunctival injection, or infectious keratitis during the observation period.

CONCLUSIONS

According to our experience, the photochromic CL showed good visual quality, especially in terms of kinetic and functional visual acuities and subsequent high patient satisfaction, even in an indoor environment, suggesting its viability of visual correction not only in daily activities but also in indoor sports activities.

Does blue-violet filtering in contact lenses improve contrast sensitivity?

PURPOSE

The work is aimed at (i) comparing photopic contrast sensitivity (CS) of healthy subjects in an indoor environment with either blue-violet filtering (BVF) or clear contact lenses (CLs) and (ii) investigating a possible dependence of the CS variation on the subjects' intrinsic CS, measured with clear CLs.

METHODS

Optical transmittance of BVF and clear CLs was measured by a spectrophotometer. Photopic CS was measured monocularly on forty-one subjects (nineteen in the age range 20-36 years and twenty-two in the age range 44-66 years) by a digital optotype system at spatial frequencies from 1.5 to 18 cpd, wearing either clear or BVF CLs. The results are indicated as CS_clear and CS_BVF, respectively.

RESULTS

Transmittance curves in the visible range of the two CLs are very similar, despite an absorption band in the BVF CL spectrum with the minimum of transmittance at 428 ± 4 nm equal to about 79%. For both CS_clear and CS_BVF, no significant CS difference was found between younger and older adults. The difference [log(CS_BVF) - log(CS_clear)] showed a decreasing trend and changed sign from positive to negative as a function of log(CS_clear) with correlation Spearman's Rho coefficients ranging from 0.80 to 0.88 (p < 0.01 at all spatial frequencies).

CONCLUSION

In the choice of a BVF CL, practitioners should take into consideration that it can influence photopic CS, improving it for subjects who have a relatively low CS with clear CLs, and worsening it for subjects who have a relatively high CS with clear CLs. BVF can affect positively the CS by reducing intraocular scattering. However, it can also cause a reduction in light intensity, which contributes to the formation of the retinal image. The positive or negative influence of BVF CLs compared to clear ones on CS is attributed to a balance among these effects.

Piggyback Photochromic Contact Lens for Visual Rehabilitation and Photophobia Management in Traumatic Aniridia

ABSTRACT

We report herein a case of fitting with a photochromic silicone hydrogel contact lens under a rigid gas-permeable lens (piggyback system) for photophobia and low vision correction after traumatic aniridia and aphakia. A 40-year-old woman was referred to our practice for contact lens fitting in her right eye, which was left aphakic after an open globe injury. She also presented traumatic aniridia in the right eye, and her left eye had been previously eviscerated. A successful fitting was obtained with a photochromic silicone hydrogel (senofilcon A) contact lens, with a Dk/t of 121 × 10-9, under an aspheric design, +13.00 D rigid gas-permeable lens. The patient displayed visual acuity and contrast sensitivity improvement and reported decreased photophobia.

The Effects of a Senofilcon A Contact Lens With and Without a Photochromic Additive on Positive Dysphotopsia Across Age

OBJECTIVE

The visual effects of wearing a photochromic contact lens (test) were directly compared with a nonphotochromic contact lens (control). Positive dysphotopsia (halos, starbursts) and intraocular scatter (behaviorally determined) were assessed. Both younger and middle-aged subjects were evaluated to examine the influence of age.

METHODS

Fifty-four subjects (18-62 years) were tested using a contralateral design. Subjects were fit with a photochromic contact lens on one eye and a nonphotochromic contact lens on the other eye, randomly assigned. Testing occurred with and without photochromic activation (darkened) by use of a violet activator (365 nm, half-bandwidth 20 nm). The extent of dysphotopsia (halos and spokes) was measured using an aperture (∼4 mm) that created a bright point source of light 45 inches from the plane of the eye. Between the point source and subject, a centering precision caliper was used to measure lateral spread. Two-point thresholds were determined by measuring the minimum distance between two points of broadband xenon light.

RESULTS

The photochromic contact lens produced smaller halo diameters than the control contact lens, both activated (41% on average) and inactivated (21% on average), and age strata was a significant factor (P<0.001) with the older group showing a greater reduction. The photochromic contact lens produced smaller starburst diameters than the control contact lens, both activated (37% on average) and inactivated (23% on average), and age strata was a significant factor (P=0.001) with the older group showing a greater reduction. The two-point thresholds were reduced (25% activated, 9% inactivated) on average but the age effect was not significant (P<0.10).

CONCLUSIONS

The senofilcon A lens with photochromic additive reduced the extent of positive dysphotopsia compared with the same lens without the additive, regardless whether the lens was activated or not. The visual benefit was greatest with the older subjects.

CLEAR - Contact lens technologies of the future

Contact lenses in the future will likely have functions other than correction of refractive error. Lenses designed to control the development of myopia are already commercially available. Contact lenses as drug delivery devices and powered through advancements in nanotechnology will open up further opportunities for unique uses of contact lenses. This review examines the use, or potential use, of contact lenses aside from their role to correct refractive error. Contact lenses can be used to detect systemic and ocular surface diseases, treat and manage various ocular conditions and as devices that can correct presbyopia, control the development of myopia or be used for augmented vision. There is also discussion of new developments in contact lens packaging and storage cases. The use of contact lenses as devices to detect systemic disease has mostly focussed on detecting changes to glucose levels in tears for monitoring diabetic control. Glucose can be detected using changes in colour, fluorescence or generation of electric signals by embedded sensors such as boronic acid, concanavalin A or glucose oxidase. Contact lenses that have gained regulatory approval can measure changes in intraocular pressure to monitor glaucoma by measuring small changes in corneal shape. Challenges include integrating sensors into contact lenses and detecting the signals generated. Various techniques are used to optimise uptake and release of the drugs to the ocular surface to treat diseases such as dry eye, glaucoma, infection and allergy. Contact lenses that either mechanically or electronically change their shape are being investigated for the management of presbyopia. Contact lenses that slow the development of myopia are based upon incorporating concentric rings of plus power, peripheral optical zone(s) with add power or non-monotonic variations in power. Various forms of these lenses have shown a reduction in myopia in clinical trials and are available in various markets.

Contact lenses, the reverse Pulfrich effect, and anti-Pulfrich monovision corrections

Interocular differences in image blur can cause processing speed differences that lead to dramatic misperceptions of the distance and three-dimensional direction of moving objects. This recently discovered illusion-the reverse Pulfrich effect-is caused by optical conditions induced by monovision, a common correction for presbyopia. Fortunately, anti-Pulfrich monovision corrections, which darken the blurring lens, can eliminate the illusion for many viewing conditions. However, the reverse Pulfrich effect and the efficacy of anti-Pulfrich corrections have been demonstrated only with trial lenses. This situation should be addressed, for clinical and scientific reasons. First, it is important to replicate these effects with contact lenses, the most common method for delivering monovision. Second, trial lenses of different powers, unlike contacts, can cause large magnification differences between the eyes. To confidently attribute the reverse Pulfrich effect to interocular optical blur differences, and to ensure that previously reported effect sizes are reliable, one must control for magnification. Here, in a within-observer study with five separate experiments, we demonstrate that (1) contact lenses and trial lenses induce indistinguishable reverse Pulfrich effects, (2) anti-Pulfrich corrections are equally effective when induced by contact and trial lenses, and (3) magnification differences do not cause or impact the Pulfrich effect.

Individual differences in visual function

A significant proportion of research on the visual system focuses on general principles that apply to samples and/or populations. Many questions, however, are more suited to the specific characteristics of an individual. The visual system, like most systems of the body, is extremely variable with respect to function and susceptibility to disease. Understanding this variation is an important avenue to better measurement, disease prevention and treatment.