Sunscreens Part 1: Mechanisms and Efficacy.

As our knowledge of the harmful effects of ultraviolet radiation continues to evolve, sunscreen remains an integral part of a comprehensive photoprotection strategy against multiple endpoints of ultraviolet-mediated damage. Part 1 of this review covers sunscreen active and additive ingredient properties, mechanisms of action and gaps in coverage. Following an overview of sunscreen's efficacy in protecting against sunburn, photocarcinogenesis, photoaging, pigmentary disorders, and idiopathic photodermatoses, we highlight considerations for product use and selection in children and individuals with skin of color.

Evaluation of the protection of sunscreen products against long wavelength ultraviolet A1 and visible light-induced biological effects.

BACKGROUND: Long wavelength ultraviolet-A1 in combination with visible light induces hyperpigmentation, particularly in dark-skin phototypes. This study evaluated the efficacy of four sunscreen formulations in protecting against VL + UVA1 (370-700 nm). METHODS: The test products (A-D) were applied to the back of 12 volunteers, then irradiated with 320 J/cm2 VL + UVA1 (3.5% UVA1 [370-400 nm]). Immediately after irradiation, and at Days 1, 7, and 14, erythema and pigmentation were assessed by investigator global assessment (IGA), colorimetry (Δa* and ΔITA) and diffuse reflectance spectroscopy (DRS)-measured relative dyschromia (area under the curve AUC). Control areas were irradiated without sunscreen. RESULTS: Product D, containing titanium dioxide 11%, iron oxides 1%, and antioxidants, provided the highest and most consistent protection. Compared with unprotected irradiated control, it had statistically significantly less erythema on IGA, DRS (Δoxyhemoglobin), and colorimetry (Δa*) at Day 0; less pigmentation on IGA at all time points, on DRS (relative dyschromia) at Days 7 and 14, and on colorimetry (ΔITA) at Day 0. Product B, containing zinc oxide 12% plus organic UV filters, iron oxides 4%, and antioxidants, also showed some efficacy. CONCLUSION: Of the sunscreens tested, the tinted products provided better protection against VL + UVA1 than the non-tinted products. Since the product with 1% iron oxides was superior to the product with 4% iron oxides, further studies are needed to evaluate whether iron oxide content correlates with better protection.

Subjective and objective assessment of color match of universal tinted sunscreens in Fitzpatrick skin phototypes I-VI.

BACKGROUND: Tinted sunscreens not only shield against UV rays but also provide protection against visible light, as opposed to traditional sunscreens. Universal tinted sunscreens are marketed to complement all skin tones. OBJECTIVE: To assess color match and subject satisfaction for 7 universal tinted sunscreens across various price ranges in all Fitzpatrick skin phototypes (SPT). METHODS: Products A-G were applied at concentrations of 1 and 2 mg/cm2 on the dorsal arms of 30 subjects spanning SPT I-VI. Photography, colorimetry, and subject and investigator surveys were utilized to determine color match. RESULTS: Using colorimetry analysis at the recommended 2 mg/cm2 concentration, two of seven products were identified as suitable matches for SPT I-II, while six out of seven were determined to be a good match for SPT III-IV. However, only one product was found to be a good match for SPT V-VI at the recommended concentration according to colorimetry results. CONCLUSION: Universal tinted sunscreens do not provide an adequate color match for all skin phototypes, especially for individuals with very fair or very dark skin tones.

Masking Colour Blindness: A Case Report.

Colour vision is an important aspect of visual function that might help individuals in doing daily activities. Some occupations require and test for good colour discrimination. We describe a case of a 20-year-old man who was referred to our centre to establish if he had colour vision deficiency (CVD). He had been tested for this twice as part of his assessment to enter the police force. At the first examination, he had normal colour vision, while the second examination revealed CVD, thus the patient was referred for confirmation. Colour vision tests using the Ishihara plates showed normal results with each eye, while a Roth test revealed an unspecified CVD in the right eye and deuteranopia in the left eye. During the evaluation, we noticed he was using a red-tinted contact lens in the right eye, and was wearing a red mask with transparent red plastic in the upper part. After removal of the contact lens and mask, he was asked to repeat the examinations and it revealed deuteranopia in both eyes. A tinted contact lens is a corrective device that can help to enhance colour discrimination in CVD subjects. However, in this case the tinted contact lens was used inappropriately to manipulate the colour vision examination. We highlight the case to raise awareness that the use of red contact lenses and red filters can mask CVD.

Post-concussion Syndrome Light Sensitivity: A Case Report and Review of the Literature.

Photophobia is considered the second most common symptom of both concussion and post-concussion syndrome. Soldiers on duty experience photophobia after blast-related concussions or mild traumatic brain injury in 60-75% of instances. In addition, soldiers report other symptoms, such as asthenopia, squinting, dry eyes and headaches, for which they are considered to be at high risk. According to the International Brain Injury Association, some concussed patients report indirect symptoms such as multi-tasking difficulties, dizziness, vertigo, and fatigue. Moreover, some concussed individuals experience photophobia for approximately 6 months or indefinitely. We present the case of a 23-year-old soldier who presented with severe photophobia after a mild traumatic head injury. His photophobia was alleviated after the administration of topical anaesthetic drops in the eyes in the absence of any ocular surface pathology. He was diagnosed with post-concussion syndrome light sensitivity and was managed successfully with rose-coloured special photophobia glasses tinted with FL-41. Photophobia is a common neurological symptom in military personnel that needs more attention as it affects body and mind. We have reported an uncommon pathway of photophobia, which may unveil an unrecognised mechanism that may play a role in post-concussion photophobia.

Photoprotection beyond ultraviolet radiation: A review of tinted sunscreens.

Ultraviolet radiation and visible light both have biologic effects on the skin. Visible light can induce erythema in light-skinned individuals and pigmentation in dark-skinned individuals. Broad-spectrum sunscreens protect against ultraviolet radiation but do not adequately protect against visible light. For a sunscreen to protect against visible light, it must be visible on the skin. Inorganic filters (also known as mineral filters), namely, zinc oxide and titanium dioxide, are used in the form of nanoparticles in sunscreens to minimize the chalky and white appearance on the skin; as such, they do not protect against visible light. Tinted sunscreens use different formulations and concentrations of iron oxides and pigmentary titanium dioxide to provide protection against visible light. Many shades of tinted sunscreens are available by combining different amounts of iron oxides and pigmentary titanium dioxide to cater to all skin phototypes. Therefore, tinted sunscreens are beneficial for patients with visible light-induced photodermatoses and those with hyperpigmentation disorders such as melasma and postinflammatory hyperpigmentation.

Effect of Blue Light Filtering Intraocular Lenses on Visual Perception.

Background and Objectives: This retrospective consecutive case control study compares best-corrected visual acuity (BCVA), mesopic contrast sensitivity (CS), color vision, and glare between a group of eyes with blue-light-filtering intraocular lenses and another with UV-light-filtering intraocular lenses. Materials and Methods: We used Early Treatment Diabetic Retinopathy Study charts to compare BCVA, Rabin charts for mesopic CS testing, Oculus HMC Anomaloscope MR to test for chromatic discrimination, and Oculus Mesotest II to measure scotopic CS with glare. For analysis, we used descriptive statistics and compared means with parametric and non-parametric tests. The level of significance was set as α = 0.05. Results: For the group with the blue-light-filtering intraocular lens, the average results were BCVA = 0.96 (SD ± 0.09), CS = 1.78 log (SD ± 0.12), chromatic discrimination results M = 63.91 (SD ± 11.88), R = 60.07 (SD ± 7.89). For mesopic CS with glare, the group achieved on average 2.54 (SD ± 1.50) points out of 4. For the group with the UV-light-filtering intraocular lens, the average results were BCVA = 0.93 (SD ± 0.14), CS = 1.79 log (SD ± 0.13), chromatic discrimination results M = 65.38 (SD ± 17.14), R = 60.79 (SD ± 10.39). For mesopic CS with glare, this group achieved an average of 2.79 (SD ± 1.53) points out of 4. Conclusion: No significant differences (p > 0.05) were found in any of the tested parameters between the analyzed groups. Slight shift in color vision was observed, although not statistically significant.

Application of an Easy-to-Perform High-Energy and Low-End Visible Light Transmittance Method and the Influence of Tinted Sunscreens on High-Energy/Low-End Visible Light Transmittance and Infrared Protection.

BACKGROUND: About 50% of the sun's radiation arriving on earth is visible light (VIS). For a long time, its effects on human health have not been fully investigated. But recently, the influence of VIS has gained more attention, especially regarding skin physiology. Studies showed various effects, many of them harmful, comparable to UV radiation. As a result, there are now a few sunscreens commercially available which claim protection against VIS. The question of whether protection is necessary is still much discussed. AIMS: The objective of this study was to develop an easy-to-perform high-energy visible (HEV) and low-end visible (LEV) light transmittance method to determine the direct VIS protection of sunscreens and other cosmetic samples. Furthermore, the influence of the brightness of the tested products on the HEV, LEV, and infrared A protection was investigated. METHODS: An experimental setup consisting of a light source, a VIS-transmissible filter system, and a sensor unit was built to measure the direct VIS protection of sunscreens and other daily skin care products in two ranges of the VIS area. For a closer look, the brightness of the samples was evaluated by photometric assessment. RESULTS/CONCLUSION: The experimental setup could be validated. It could be demonstrated for the first time that there is a strong positive linear correlation between transmittance and brightness of tinted sunscreen and daily skin care products with sunscreen properties in the HEV, LEV, and infrared A range. However, tinted samples worked best in the blue light region, and the higher the wavelength range, the lower the protection.

Estimations of Retinal Blue-Light Irradiance Values and Melatonin Suppression Indices Through Clear and Yellow-Tinted Intraocular Lenses.

Spectral transmittance values in the wavelength range of 300 to 800 nanometers were measured using a spectrophotometer for 18 intraocular lenses (IOLs) including clear (ZCB00) and yellow-tinted (ZCB00V, both from AMO Japan) IOLs with three different lens powers. Also measured were the blue-light irradiance (BLI) values, which might reflect retinal damage caused by sunlight, and the melatonin suppression indices (MSIs), which might reflect the nonvisual photoreception function, through these IOLs. The BLIs (in mWcm-2) calculated were 7.62, 7.50, and 7.46 for the +10-diopter (D), +20-D, and +30-D ZCB00 IOLs, respectively; 4.10, 3.92, and 4.00 for the +10-D, +20-D, and +30-D ZCB00V IOLs, respectively; 5.76 for phakic eyes; and 15.00 for aphakic eyes. The MSIs (in mWcm-2sr-1) calculated were 1.18, 1.19, and 1.18 for the +10-D, +20-D, and +30-D ZCB00 IOLs, respectively; 0.98, 0.94, and 0.95 for the +10-D, +20-D, and +30-D ZCB00V IOLs, respectively; 1.03 for phakic eyes; and 1.21 for aphakic eyes. The data from the six clear IOLs (SA60AT, Alcon Japan; VA-60BBR, Hoya; AU6 K, Kowa, N4-18B, Nidek; X-60, Santen; KS-3Ai, Staar Japan) and seven yellow-tinted IOLs (SN60AT; YA-60BBR, Hoya; AU6N, Kowa; N4-18YG, Nidek; NX-60, Santen; KS-AiN, Staar Japan; XY-1, Hoya) reported previously also were discussed. Compared to aphakic eyes, ZCB00 and ZCB00V IOLs reduce the BLI values by 49-50% and 73-74%, respectively; and currently available ultraviolet-blocking clear and yellow-tinted IOLs reduce the BLI values by 43-82%, respectively. Yellow-tinted IOLs absorb more circadian rhythm-associated light than clear IOLs. Although the data presented in this study cannot be applied directly to IOL implanted in patients, the balance between photoprotection and photoreception must be considered when using IOLs in a clinical setting.

Photoprotection against visible light-induced pigmentation.

OBJECTIVE: This paper presents in vivo an in vitro studies demonstrating the induction of pigmentation in human skin by visible light which can be blocked by using formulation containing the correct amount of yellow iron oxide (YIO). METHODS: An in vitro absorption method was developed to determine the protection provided by a test formulation containing 4.5% YIO using an IPD UVA-VIS action spectrum. Following the development of the in vitro method and in vivo study with 10 normal healthy volunteers with Fitzpatrick skin phototypes IV to VI was conducted to verify if the predictive model. RESULTS: The in vitro model for visible light protection provided a protection factor of 2.5 using the in vitro absorption spectrum of 4.5% of YIO with a very similar result from the in vivo study with a protection factor of 3.0. Multiple daily exposures of visible light have shown increase in skin pigmentation and the application of YIO provide less development of pigmentation when compared to unprotected skin. CONCLUSION: In vitro testing of the absorbance of the pigmented formulation using a proposed action spectrum for immediate pigment darkening (IPD) response in the visible light range supports the in vivo protection observations for persistent pigment darkening (PPD) and can be used as predictor for skin pigmentation induced by visible light.

Coloured overlays and precision-tinted lenses: poor repeatability in a sample of adults and children diagnosed with visual stress

PURPOSE: Visual stress consists of perceived distortions or discomfort while reading. It is claimed that these symptoms are alleviated by viewing through coloured lenses or overlays, with a specific colour required for each individual. This has been explained on the basis of altered visual cortex excitation as affected by the spectral content of the viewing light. If symptoms are indeed alleviated by a particular colour that has an impact on the individual's visual system, we would expect that selection of the most beneficial colour would be repeatable. The aim of this study was to determine whether this is the case. METHODS: Twenty-one participants (mean age 26 years (range 8-55 years); 12 female, nine male) with visual stress and no other uncorrected ocular or visual anomaly were recruited. Each participant selected the colour most beneficial in alleviating their symptoms from a standard set of 10 coloured overlays, and underwent intuitive colorimetry in which the most beneficial of a wide range of chromatic illuminance settings was selected. Without prescribing an overlay at the first appointment, this process was repeated on a second occasion at a mean of 25 days later. RESULTS: About half of the participants (n = 10) chose the same (n = 7) or similar (with one common colour in both choices; n = 3) coloured overlay on the two occasions, while 11 participants chose a completely different overlay colour. Across all participants, the colorimetry setting shifted by, on average, 9.6 just noticeable differences, indicating that the colours were perceptually very different. CONCLUSION: These findings suggest that people with visual stress are unlikely to find exactly the same colour to be optimal on different occasions, and raise questions about the need for precise colour specification in tinted lenses for visual stress.

Photosensitivity in mild traumatic brain injury (mTBI): a retrospective analysis.

PRIMARY OBJECTIVE: To determine whether photosensitivity (PS) changes over time and, if so, what factors may be related to the change; furthermore, to determine whether tint density changes over time, all in mild traumatic brain injury (mTBI). DESIGN AND METHODS: A retrospective analysis of 62 patient records (aged 18-40 years) with mTBI and PS was conducted. All charts were obtained from the SUNY/College of Optometry clinics from 2004-2011. RESULTS: Fifty per cent demonstrated reduced PS over time, with most occurring after year 1 post-injury (40%). Promotion of PS reduction appears to be associated with the lack of spectacle tint usage (p = 0.01) and the use of contact lenses (p = 0.03). Inhibition of PS reduction appears to be associated with tinted lenses (p = 0.06), hyperacusis (p = 0.03), dry eye (p = 0.04), migraines (p = 0.03) and loss of consciousness at the time of injury (p = 0.05). Concerning tint density changes over time, 71% (p = 0.002) maintained the same degree over time, while 27% (p = 0.002) reduced and 2% waxed and waned. CONCLUSION: Neural adaptation to PS appears to be a long-term process. Tint usage may act to inhibit this adaptive process, while the use of contact lenses may act to promote it. These findings may provide guidance in the clinical management of photosensitivity in the mTBI population.

Refractive and ocular motor status in autistic adults without learning disabilities: an exploratory study.

CLINICAL RELEVANCE: Refractive and ocular motor anomalies may be more prevalent among autistic adults without learning disabilities, compared to a non-autistic clinical population. In line with current guidance, optometrists should exclude these anomalies prior to prescribing tinted lenses. BACKGROUND: Autistic adults report various visual experiences with largely negative consequences on daily living. Some of these overlap with symptoms of refractive and ocular motor anomalies. Therefore, this study investigated refractive and ocular motor status, and pattern glare, in autistic adults without learning disabilities. The impact of appropriate treatment on visual experiences was explored. METHODS: Twenty four autistic adults, aged 19-67 years, underwent an eye examination involving refraction, ocular motor and pattern glare assessments. Based on pre-determined criteria, anomalies were treated with spectacles, orthoptic exercises, or tinted lenses. Participants completed three questionnaires (Glasgow Sensory Questionnaire, Visual Function Index and Convergence Insufficiency Symptoms Survey) at the start and end of the study to assess the impact of treatment. RESULTS: Relative to population norms, a notable proportion of participants had: a significant change in refractive correction (83.3%); accommodative infacility (72.7%); convergence insufficiency (37.5%); uncompensated distance dissociated heterophoria (33.3%); significant accommodative inaccuracy (27.2%); and positive pattern glare (25%). All participants required treatment. 16.7% were given orthoptic exercises only. New spectacles were dispensed to 79.2%, followed by 16.7% requiring orthoptic exercises and 4.2% dispensed tinted lenses. Questionnaire scores did not significantly change post-treatment. CONCLUSION: This exploratory study suggests autistic adults may be more likely to present with refractive, ocular motor and pattern glare issues. Impacts on autistic visual sensory experiences, vision-related quality of life and visual function remain unclear. Pattern Glare Test scores of autistic adults appear to be reduced by appropriate refractive and/or ocular motor management. Therefore, optometrists should take a conservative approach, managing refraction and ocular motor status of autistic patients prior to considering tinted lenses.

Availability of Adequate Photoprotection for Skin of Color.

INTRODUCTION: The impact of ultraviolet (UV) light on the skin is well-established to have both immediate and delayed effects with increasing awareness of the impact of visible light (VL) on the skin with regard to photoaging and dyspigmentation. The effects of VL disproportionately impact the skin of color with regard to discoloration of the skin leading to guidelines for photoprotection that include the use of iron oxides in sunscreen products that impart a tint. METHODS: Commercially available sunscreen products found in the suncare and sun protection displays at local stores, pharmacies, and grocery stores were cataloged, and ingredients were reviewed for the presence of iron oxides. RESULTS: Of the 410 commercially available sunscreen products cataloged, 1.7% of facial sunscreen products available offered iron oxides, and 0.5% of non-lip products offered shade matching. CONCLUSION: With only 1.7% of commercially available facial sunscreen products offering iron oxides in addition to traditional broad-spectrum UV protection, there is a clear gap in the market for iron oxide-containing sunscreen products to meet the photoprotection needs for the skin of color.

Color perception on Ishihara plates with red lenses in subjects with low vision due to retinal diseases.

Purpose: This study aimed to evaluate color perception (CP) changes on Ishihara plates following red-tinted contact lenses in subjects with low vision (LV) from retinal diseases. Methods: A cross-sectional observational study without control involved 84 subjects, aged 20-70 years, having LV from retinal diseases to examine CP changes following wearing red-tinted contact lenses. The subjects viewed Ishihara plates, with each eye separately, before and after wearing red lenses in two categories: "plates 1-21" and "plates 22-25". Change in CP with the use of a red lens was the primary outcome measure. Results: There was a significant increase in the number of plates read in both categories, that is, plates 1-21 (P = 0.002) and plates 22-25 (P = 0.032), the latter being used to diagnose the red-green defects. Although 70 eyes could read both digits on plates 22-25 and appeared to have normal color vision (CV) at baseline, this number rose to 99 eyes following the use of red-tinted lenses. There was a significant change in the type of CP (red defect/green defect/normal/undefined defect) (P = 0.022) with the application of a red-tinted lens. Conclusions: The use of red-tinted lenses caused a significant increase in the number of plates read, increased the number of subjects who appeared normal on plates 22-25, and significantly changed CP of LV subjects. These lenses can be a valuable aid for LV subjects. Although Ishihara plates can diagnose only red-green defects, further studies on CV testing techniques that detect both red-green and blue-yellow CV defects are recommended.

Application of colored filters in patients post-traumatic brain injury: A review.

BACKGROUND: Tinted lenses have been used to manage visual discomfort and photosensitivity in patients with migraines, benign essential blepharospasm (BEB) and epilepsy. OBJECTIVES: The purpose of this review is to examine the existing clinical research regarding the use of colored filters among patients recovering from traumatic brain injuries. METHODS: A review of English articles from PubMed, Embase from embase.com, Web of Science, APA PsycINFO (OVID), Scopus, and Cochrane Central Register of Controlled Trials with publication years from date of inception to June 10, 2021 was performed. Articles were first screened by title and abstract, followed by full-text review. The search strategy resulted in 7819 results. The final analysis included seven articles which discussed the use of tinted lenses in patients post-traumatic brain injury. RESULTS: While there is a paucity of information related to the therapeutic use of tinted lenses to mitigate post-traumatic light sensitivity and migraines, patients will subjectively report improved symptoms, specifically with precision tints or FL-41. CONCLUSION: Further studies are needed to understand the mechanism of action as well as objective and subjective benefits of tinted lenses in patient post-traumatic brain injury.

Protective Football Headgear and Peripheral Visuomotor Ability in NCAA Football Athletes: The Role of Facemasks and Visors.

The purpose of this investigation was to determine the effects of varying facemask reinforcement and visor tint on peripheral visuomotor abilities in collegiate football players. Division I NCAA football players (n = 14) completed two peripheral visuomotor experiments: (1) Varying facemask reinforcement, (2) Varying visor tinting. In experiment 1, participants were tested under the following conditions: baseline (no helmet; BL), helmet + light (HL), helmet + medium (HM), helmet + heavy (HH), and helmet + extra heavy (HXH) reinforced facemasks. In experiment 2, participants were tested under the following conditions: baseline (no helmet; BL), helmet only (HO), helmet + clear (HCV), helmet + smoke-tinted (HSV), and helmet + mirror-tinted (HMV) visors. For each condition, a 60 s peripheral visuomotor test was completed on a Dynavision D2 visuomotor board. For experiment 1, the BL peripheral reaction time (PRT) was faster than all facemask conditions (p < 0.05). Furthermore, PRT was impaired with the HXH compared to HL (p < 0.001), HM (p < 0.001), and HH (p = 0.001). Both HH and HXH resulted in the potentiation of PRT impairments in the outermost and inferior peripheral visual areas (p < 0.05). In experiment 2, BL PRT was faster than all helmeted conditions (p < 0.05). Additionally, PRT was slower in HSV (p = 0.013) and HMV (p < 0.001) conditions compared to HO. HMV resulted in slower PRT in all peripheral areas (p < 0.05) while PRT was impaired only in outer areas for HSV (p < 0.05). Wearing protective football headgear impairs peripheral visuomotor ability. Lighter reinforced facemasks and clear visors do not appear to exacerbate impairment. However, heavier reinforced facemasks and tinted visors further decrease visuomotor performance in outer and inferior visual areas, indicating a potential need for considerations of on-field player performance and safety.

Can Tinted Lenses Be Used to Manipulate Pupil Size and Visual Performance When Wearing Multifocal Contact Lenses?

BACKGROUND: The purpose of this study is to investigate the effect of wearing neutral density (ND) filters with different transmittance levels over multifocal contact lenses (MTF CLs) on pupil size, visual functions and the dynamic accommodative response under daylight conditions in early presbyopes. METHODS: Seventeen individuals aged between 40 and 48 years (mean age 42.35±2.62 years) were recruited to participate in this study. This study involved a repeated-measures design with two within-subject factors: optical condition (which had five levels), and fixation distance (which had three levels). The five optical conditions were no correction (baseline), MTF CL wear, MTF CL wear + 0.3 ND filter (transmission [Tv]=48.38%), MTF CL wear + 0.6 ND filter (Tv=27.12%) and MTF CL wear + 0.9 ND filter (Tv=14.58%). The three fixation distances were 3 m, 40 cm and 20 cm. Outcome measures were pupil size, the measured accommodative response (optical aid + physiological accommodation), distance visual acuity (VA), near VA and contrast sensitivity (CS). RESULTS: There was no effect of optical condition on the accommodative response; however, there was a significant effect of fixation distance. (Accommodative response was 0.44±0.29, 1.83±0.37 and 4.03±0.46 D for fixation distances of 3 m, 40 cm and 20 cm, respectively; p<0.05.) There was a significant effect of optical condition (p<0.05) and of fixation distance on pupil size variation (5.13±0.90 mm for 3 m, 4.71±0.92 mm for 40 cm and 4.11±1.04 mm for 20 cm; p<0.05). Optical condition had a significant effect on distance VA, near VA and CS (p<0.05). Compared to the reduction in distance VA, near VA was relatively small (two-letter reduction with 0.9 ND) and unlikely to be clinically significant. CONCLUSION: This study demonstrated that in a group of adults with early presbyopia, the use of ND filters enlarged pupil size. However, the combination of enlarged pupils and MTF CL did not improve distance vision, and if transmittance was reduced by 50% it resulted in decrements in vision and CS. MTF CL designs which incorporate tints, or tints that vary in darkness in response to ultraviolet exposure, should consider these findings.