New formulation technology to boost sun protection.

OBJECTIVE: As every skin type worldwide is concerned by photoprotection, with consumers preferring cosmetic elegant and efficient sunscreen products, we aim at developing the most performant and desirable sun care products. METHODS: We selected an interesting polymer, abbreviated AAHCP and designed scanning electron cryomicroscopy (cryoSEM), small angle and wide angle X-ray scattering and confocal laser scanning microscopy studies to understand its behaviour in solution and in simplex sun care formulations. This allowed us to develop innovative sunscreen formulation technology that was demonstrated by in vitro and in vivo photoprotection methods. Comprehensive photoprotection evaluations were made on the fully developed sun protection product. RESULTS: We observed the polymer oil structuring properties as well as its ability to form small and stable droplets in simplex emulsions. In vitro and in vivo sun protection factor (SPF) measurements demonstrated the sun protection boosting efficacy of AAHCP polymer in several emulsions or as a stand-alone emulsifier. This formulation technology also allowed to filtering system concentration optimization. Use-test performed on a fully developed AAHCP-based sunscreen validated its optimal performances as well as its ideal cosmetic features, with non-sticky, non-greasy perception and invisible skin result. CONCLUSION: For the first time, thanks to a new specific polymer creating a new type of emulsion, we succeed in reconciliate in a single sun care product maximal SPF efficacy, resistance to numerous stresses and optimal sensoriality.

OBJECTIF: Tous les types de peau du monde étant concernés par la photoprotection, avec des consommateurs qui préfèrent des produits solaires élégants et efficaces, nous nous sommes donné pour mission de développer les produits de protection solaire les plus performants et les plus agréables. MÉTHODES: Nous avons sélectionné un polymère intéressant, l'« AAHCP ¼ dans sa forme abrégée, et avons conçu les études de cryomicroscopie électronique à balayage (CryoSEM), de diffusion des rayons X et de microscopie confocale à balayage laser (Confocal Laser Scanning Microscopy) pour comprendre son comportement en solution et dans des formulations de protection solaire simples. Cela nous a permis de développer une technologie innovante de formulation de protection solaire, qui a été démontrée par des méthodes de photoprotection in vitro et in vivo. Le produit de protection solaire a fait l'objet d'évaluations exhaustives de la photoprotection à la fin de sa phase de développement. RÉSULTATS: Nous avons observé les propriétés de structuration de l'huile polymère, ainsi que sa capacité à former de petites gouttelettes stables dans les émulsions de simplex. Les mesures du facteur de protection solaire (sun protection factor, SPF) in vitro et in vivo ont montré que la présence du polymère AAHCP dans plusieurs émulsions ou comme émulsifiant autonome optimise le niveau de protection solaire obtenu. Cette technologie de formulation a également permis d'ajuster la concentration du système de filtration. Le test en conditions réelles d'utilisation effectué sur une protection solaire à base d'AAHCP à la fin de la phase de développement a permis de valider ses performances optimales, ainsi que ses caractéristiques cosmétiques idéales, avec une sensation non collante et non grasse, et un résultat invisible sur la peau. CONCLUSION: Pour la première fois, grâce à un nouveau polymère spécifique créant un nouveau type d'émulsion, nous avons réussi à développer un produit de protection solaire simple à l'efficacité SPF maximale, qui résiste à de nombreuses contraintes et possède une sensibilité optimale.

[Characterization of sun protection performance: Quo vadis?] / Charakterisierung von Sonnenschutzleistung: Quo vadis?

The task of the first sunscreens was to prevent the development of sunburn and, following the spirit of the 1950/1960s, to not impair the tanning of the skin. The need to quantify the protective performance soon arose. Originally with the help of natural-nowadays artificial-sunlight, a method was developed to determine a sun protection factor (SPF). It is formally defined as a ratio between minimum erythema-effective UV dose on sunscreen-protected skin and minimum erythema-effective UV dose on unprotected skin (ISO 24444:2019). Three observations question the suitability of the method. (1) Interlaboratory variability: Despite strict standardization, results of SPF determinations from different laboratories are subject to large variations. (2) Natural vs. artificial sunlight: The radiation spectrum of artificial sunlight differs from that of natural sunlight. SPFs determined with artificial sunlight (as depicted on all sunscreens currently on the market) are significantly too high compared to SPF determination with natural sunlight. (3) Erythema burden: When determining SPF, subjects are exposed to potentially harmful radiation. Against this background alternative methods-in vitro SPF, hybrid diffuse reflectance spectroscopy (HDRS) and in silico calculations-are presented. These have the potential to replace the current method. As an immediate measure, it is recommended to return to the comprehensible description of low, medium, high, and very high protection and in the future to take into account the spectrum of natural sunlight.

Evaluating the Sun Protection Factor of Cosmetic Formulations Containing Afzelin.

Exposure to UV radiation damages the skin and increases the risk of skin cancer. Sunscreen is used to protect the skin from the harmful effects of UV radiation. However, the chemical UV filters used in sunscreen can show toxicity and cause allergic reactions. A safe sunscreen that includes a lower content of chemical UV filters and exerts an excellent effect on UV protection needs to be developed. The objective of this study was to investigate whether the addition of afzelin to sunscreen could improve the sun protection factor (SPF). A synergistic effect between afzelin and organic sunscreen agents including padimate O and oxybenzone was confirmed. Interestingly, 100% in vitro SPF-boosting was observed when afzelin (0.05%) was applied with a standard SPF formulation containing organic sunscreens while afzelin alone had no contribution to the SPF. In vivo SPF analysis of the standard SPF formulation showed an SPF value of 13.3 that increased to 20.1 when supplemented with afzelin (0.05%). Additionally, afzelin showed no skin irritation in a human trial. These results suggest that afzelin is useful as a natural additive in sunscreen formulations and provides an SPF-boosting effect. Afzelin supplementation to the formulation showed the potential to reduce the use of synthetic photoprotectors, which could minimize the risk of synthetic agent toxicity.

Synthesis and Characterization of Nanostructured Lipid Nanocarriers for Enhanced Sun Protection Factor of Octyl p-methoxycinnamate.

Sunlight is important to health, but higher exposure to radiation causes early aging of the skin and skin damage that can lead to skin cancers. This study aimed at producing a stable octyl p-methoxycinnamate (OMC)-loaded nanostructured lipid carrier (NLC) sunscreen, which can help in the photoprotective effect. NLC was produced by emulsification-sonication method and these systems were composed of myristyl myristate (MM), caprylic capric triglyceride (CCT), Tween® 80 (TW), and soybean phosphatidylcholine (SP) and characterized by dynamic light scattering (DLS), zeta potential (ZP) measurement, atomic force microscopy (AFM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and in vitro release studies. Pre-formulation studies were performed changing TW concentrations and no differences were found at concentrations of 1.0 and 2.0%. Two selected formulations were designed and showed an average size of 91.5-131.7, polydispersity index > 0.2, and a negative value of ZP. AFM presented a sphere-like morphology and SEM showed ability to form a thin film. DSC exhibited that the incorporation of OMC promoted reduction of enthalpy due to formation of a more amorphous structure. Drug release shows up to 55.74% and 30.57%, and this difference could be related to the presence of SP in this formulation that promoted a more amorphous structure; the release mechanism study indicated Fickian diffusion and relaxation. Sun protection factor (SPF) evaluation was performed using NLC and presented values around 40, considerably higher than those observed in the literature. The developed formulations provide a beneficial alternative to conventional sunscreen formulations.

Formulation development and accelerated stability testing of a novel sunscreen cream for ultraviolet radiation protection in high altitude areas.

The present study is aimed at the development of a sunscreen cream for use in high altitude areas which have been found to possess superior sun protection factor (SPF) along with remarkable antioxidant activity. The topical formulation is a standard oil-in-water emulsion of a combination of United States Food and Drug Administration (US FDA) approved ultraviolet filters; along with melatonin and pumpkin seed oil. The in-silico optimized formulation was characterized using established methods and the stability study was carried out as per International Conference on Harmonization guidelines. The formulation was prepared after requisite pre-formulation analysis by Fourier-transform infrared spectroscopy, differential scanning calorimetric and thermogravimetric analyses; followed by characterization based on color, odor, phase separation, spreadability, specific gravity, homogeneicity, centrifugation and sensitivity. For the stability study, a total of three samples from three batches of the finished product were subjected to the stability study. The samples were analyzed for content uniformity, pH, in vitro SPF, rheology, zeta potential, droplet diameter and microbial analysis of the 0th day and also the the end of the storage period. Results obtained from the stability study indicated that the formulation possesses 50+ in vitro SPF value and remained stable for 6 months and 12 months under storage at 40 ± 2 °C and 75 ± 5% relative humidity; and -20 °C ± 5 °C respectively.

SPF 100+ sunscreen is more protective against sunburn than SPF 50+ in actual use: Results of a randomized, double-blind, split-face, natural sunlight exposure clinical trial.

BACKGROUND: The value of additional photoprotection provided by use of high-sun protection factor (SPF) sunscreens is controversial, and limited clinical evidence exists. OBJECTIVE: To compare the sunburn protection provided by SPF 100+ and SPF 50+ sunscreen in conditions of actual use. METHODS: A total of 199 healthy men and women (≥18 years) participated in a natural sunlight, single-exposure, split-face, randomized, double-blind study in Vail, Colorado. Each participant wore both sunscreens simultaneously during activities, with no use restrictions other than designation of the treatment area. Erythema was clinically assessed on the day following exposure. Comparative efficacy was evaluated through bilateral comparison of sunburn between treatment areas and erythema score, as evaluated separately for each treatment area. RESULTS: Following an average 6.1 ± 1.3 hours of sun exposure, investigator-blinded evaluation identified 55.3% of the participants (110 of 199) as more sunburned on the SPF 50+ protected side and 5% (10 of 199) on the SPF 100+ protected side. After exposure, 40.7% of the participants (81 of 199) exhibited increased erythema scores (by ≥1) on the SPF 50+ protected side as compared with 13.6% (27 of 199) on the SPF 100+ protected side. LIMITATIONS: Single-day exposure may not extrapolate to benefits of longer-term protection. CONCLUSION: SPF 100+ sunscreen was significantly more effective in protecting against sunburn than SPF 50+ sunscreen in actual use conditions.

Hybrid Diffuse Reflectance Spectroscopy: Non-Erythemal in vivo Testing of Sun Protection Factor.

BACKGROUND/AIMS: In order to define a label sun protection factor (SPF) of topically applied sunscreens, in vivo test methods like ISO 24444, FDA guideline, or the Australian standard are used worldwide. The basis of all these methods is provoking an erythemal skin reaction by UV irradiation to find the level of unprotected and protected minimal erythemal doses (MED). In vitro methods replacing the human skin by any kind of non-human material are still not available. Thus, offering the new hybrid diffuse reflectance spectroscopy (HDRS) technique that is able to stay on an in vivo level for SPF testing but meanwhile neglecting the UV-dose-related erythemal skin reaction is a perfect combination to take care of sun protection and any ethical concerns in SPF testing nowadays. METHODS: HDRS is a combination of in vivo diffuse reflectance spectroscopy (DRS) measurements on the skin and in vitro transmission measurements of a sunscreen on a roughened polymethylmethacrylate plate. By this technique, the in vivo behavior of the investigated sunscreen on the skin is measured as well as the UVB absorption, which is still non-visible in the reflectance technique. In order to establish an alternative method for in vivo SPF testing, a huge number of sunscreens (80 samples) was measured by HDRS and compared to the worldwide accepted standard ISO 24444. The variety of sunscreens measured reflects a wide range of different types of formulations as well as a wide range of SPFs (5-120) to validate this new alternative SPF testing procedure. RESULTS: The applied quantity of product as well as skin color dependencies of signal generation are shown to support any basic correlation of DRS signal generation and sun protection expectations. Far-reaching statistical data analyses show an excellent link of the new non-erythemally driven HDRS-SPF technique and ISO 24444 results. In the same way, HDRS-UVA-PF results can be correlated with UVA-PF values calculated from ISO 24443. CONCLUSION: Due to the elimination of any erythemal relevant UVB and UVA doses, absolutely no skin reaction occurs. Consequently there is no need to define a MED any more. For the first time an alternative way to SPF is shown without any ethical concerns of SPF testing in vivo and/or any restriction of SPF testing in vitro. Regardless of the type of formulation or the level of protection, an excellent correlation of SPFHDRS and SPF24444 for sunscreen labeling could be found. By this new alternative non-erythemal technique, not only SPF values can be measured, but also UVA-PF values can be calculated with an excellent correlation to ISO 24443 from the same set of data. For the first time a robust alternative test method of SPF- and UVA-PF values is described, taking into account the interaction of sunscreen formulation and skin.

A new in vitro method to determine sun protection factor.

A new in vitro sun protection factor (SPF) test method to determine the efficacy of sun care products is proposed and evaluated. Based on ultraviolet (UV) dose cumulate response protocols, the new method employs Gafchromic EBT3 film, a self-developing dosimetry film originally created for applications in radiotherapy. Unlike the current standardized method, a UV spectrophotometer is not required. In vitro SPF values of 15 commercial products were measured with EBT3 film and compared with labeled in vivo SPF values. It is apparent that the new method is accurate, cost-effective, and reproducible. These results can be seen across sun care product lines, including sunscreen lotions, blemish balm (BB) creams, foundations, and sprays with organic and\/or inorganic UV filters.

New noninvasive approach assessing in vivo sun protection factor (SPF) using diffuse reflectance spectroscopy (DRS) and in vitro transmission.

BACKGROUND/PURPOSE: In the past 56 years, many different in vitro methodologies have been developed and published to assess the sun protection factor (SPF) of products, but there is no method that has 1:1 correlation with in vivo measurements. Spectroscopic techniques have been used to noninvasively assess the UVA protection factor with good correlation to in vivo UVA-PF methodologies. To assess the SPF of sunscreen product by diffuse reflectance spectroscopy (DRS) technique, it is necessary to also determine the absorbance spectrum of the test material in the UVB portion of the spectrum (290-320 nm). However, because of the high absorbance characteristics of the stratum corneum and epidermis, the human skin does not remit enough UVB radiation to be used to measure the absorption spectrum of the applied product on skin. In this work, we present a new method combining the evaluation of the absolute UVA absorption spectrum, as measured by DRS with the spectral absorbance 'shape' of the UVB absorbance of the test material as determined with current in vitro thin film spectroscopy. METHODS: The measurement of the in vivo UVA absorption spectrum involves the assessment of the remitted intensity of monochromatic UVA radiation (320-400 nm) before and after a sunscreen product was applied on skin using a spectrofluorimeter Fluorolog 3, FL3-22 (Yvon Horiba, Edison, NJ, USA). The probe geometry assures that light scattering products as well as colored products may be correctly assessed. This methodology has been extensively tested, validated, and reported in the literature. The in vitro absorption spectrum of the sunscreen samples and polyvinyl chloride (PVC) films 'surrogate' sunscreen standards were measured using Labsphere® UV-2000S (Labsphere, North Sutton, NH, USA). Sunscreens samples were tested using PMMA Helioplates (Helioscience, Marseille, France) as substrates. The UVB absorbance spectrum (Labsphere) is 'attached' to the UVA absorbance spectrum (diffuse reflectance) with the UVB absorbance matched to the UVA absorbance at 340 nm to complete the full spectral absorbance from which an estimate the SPF of the product can be calculated. RESULTS: Seventeen test materials with known in vivo SPF values were tested. Two of the tested products were PVC sunscreen thin films with 10-15 micrometers thickness and were used to investigate the absorption spectrum of these films when applied on different reflectance surfaces. Similar to the human in vivo SPF test, the developed methodology suggests limiting the use on Fitzpatrick skin phototypes I to III. The correlation of this new method with in vivo clinical SPF values was 0.98 (r2) with a slope of 1.007. CONCLUSION: This new methodology provides a new approach to determine SPF values without the extensive UV irradiation procedures (and biological responses) currently used to establish sunscreen efficacy. Further work will be conducted to establish methods for evaluation of products that are not photostable.

Photoprotective characteristics of natural antioxidant polyphenols.

Fourteen natural polyphenols belonging to the classes of stilbenes, flavonoids and hydroxycinnamic acid derivatives, have been investigated in order to verify the combination of their photoprotective characteristics with their antioxidant properties. To this purpose, sun protection factor (SPF), UVA/UVB ratio and critical wavelengths (λc), have been considered to evaluate photoprotection capacity, while inhibition of lipid peroxidation has been adopted as a reliable measure of the antioxidant properties. The results obtained indicate that a large number of these natural phenol derivatives show both antioxidant activity and photoprotective characteristics and, as a consequence, they could be interesting components for pharma-photoprotection formulations. In fact, these compounds associate to a preventive function, linked to UV filtering properties, an effective action, correlated to antioxidant capacity of contrast towards UV-induced ROS injury.

Influence of lipid microparticle encapsulation on in vitro efficacy, photostability and water resistance of the sunscreen agents, octyl methoxycinnamate and butyl methoxydibenzoylmethane.

CONTEXT: Essential requirements for the efficacy of sunscreen agents are optimal UV absorption, high photostability and resistance against water removal. OBJECTIVE: Aim of this study was to investigate the effect of encapsulation in lipid microparticles (LMs) on the overall performance of the two most commonly used sunscreen agents, octyl methoxycinnamate (OMC) and butyl methoxydibenzoylmethane (BMDBM). METHODS: LMs loaded with OMC and BMDBM were prepared by melt emulsification and characterized by optical microscopy, UV filter content and release studies. The LMs incorporating OMC and BMDBM or the nonencapsulated sunscreen agents were introduced into a model cream (oil-in-water emulsion). RESULTS: No significant differences were observed between the sun protection factor (SPF) of the formulations containing the free (SPF, 9.4 ± 1.9) or microencapsulated (SPF, 9.6 ± 1.3) UV filters. Irradiation of the creams with a solar simulator demonstrated that the photodecomposition of OMC and BMDBM was significantly decreased by encapsulation in LMs from 55.7 ± 5.3% to 46.1 ± 5.1% and 36.3 ± 3.9% to 20.1 ± 4.7%, respectively. However, in vitro water-resistance studies showed that entrapment in the LMs significantly enhanced the sunscreen agent removal caused by watering (the losses for OMC and BMDBM were 45.1 ± 6.3% and 49.2 ± 8.4%, respectively), as compared to the formulation with the nonencapsulated sunscreen agents (the losses for OMC and BMDBM were 26.7 ± 6.1% and 28.0 ± 6.7%, respectively). CONCLUSION: Incorporation in LMs can have controversial effects on UV filter efficacy. In particular, the water-resistance properties of sun-care formulations containing sunscreens loaded in LMs should be verified to assure that the photoprotective activity is maintained during usage.

Sun oils: effect of the applied dose on SPF determined by using in vitro method.

The relationship between skin cancer and exposure to the sun is now clearly established. It is therefore necessary to ensure that consumers have effective sun protection. The effectiveness of the anti-solar products is quantified using a universal indicator, the SPF (sun protection factor). This value can be given in two different ways: by in vivo (standard ISO 24444:2010) and in vitro methods. The in vitro method was adopted for this study, for ethical reasons. The protective effect regarding non-melanoma cancers given by sun products has been proven. It is nevertheless a fact that consumers need to be made aware. Indeed, the quantity of sun protection product applied in reality by the consumer is clearly lower than the recommended amount. Under these conditions, the following question can be asked: What is the level of protection attained if half or even a quarter of the recommended dose of product is applied? In order to answer this question, 20 oils available on the market were tested in vitro at five different doses (5, 7.5, 10, 12.5, 15.0 mg over a surface of 25 cm(2)). We showed that a ratio of two polynomial functions exists between the SPF and the final mass of the product. The factors reducing the efficacy when the dose is divided by 2 are very variable, ranging from 2 to 4 according to which product is studied.

Investigation on the Validity of in vitro Sun Protection Factor and Ultraviolet-A Protection Factor Evaluation Method for Sunscreen Samples.

Factors affecting the in vitro Sun Protection Factor (SPF) and Ultraviolet-A Protection Factor (UVA-PF) of sunscreens were analyzed for verifying the validity and reliability of the ISO24443 evaluation method. UV absorbance measurements by different spectrophotometers did not lead to the large difference in in vitro SPF/UVA-PF, although the UV absorbance determined by each spectrophotometer exhibited relatively large difference when it was larger than 2. On the other hand, relatively large difference was found in in vitro SPF/UVA-PF by utilizing European Cosmetic and Perfumery Association (Colipa) 1994 or UV-solar simulated radiation (UV-SSR) for the spectral irradiance. Appropriateness of employing the coefficient of adjustment for the determination of in vitro UVA-PF was also found to be reexamined.

Elastic liposomes containing benzophenone-3 for sun protection factor enhancement.

This work was focused on the loading of benzophenone-3 in elastic liposomes composed of egg phosphatidylcholine and cholesterol, prepared by the Bangham method. Samples were characterized in terms of particle size, polydispersity index (PI), zeta potential, encapsulation efficiency and in vitro photoprotection properties. The extrusion of liposomes loading benzophenone-3 produced reduced-size (100 nm) elastic liposomes with a PI of 0.2. The active was loaded with a concentration of 20.34% (m/m) revealing changes in the ultraviolet properties after loading. On the basis of these results, it can be anticipated that liposomes are able to improve sun protector factor in vitro compared the free active.

Microscopic evaluation of polymeric film properties of anhydrous sunscreen compositions and their relation to absorption and water resistance.

The aim of this study was to investigate the mechanism by which a VA/butyl maleate/isobornyl acrylate copolymer increases the SPF and water resistance of sunscreen formulations. Anhydrous sunscreen formulations with and without polymer were applied on polymethyl methacrylate (PMMA) plates and absorbance spectra were generated. Before immersion, the areas under the curve for the control and test samples were 98.49 and 117.09, respectively, and were 94.63 and 118.22, after immersion. Static and after-immersion, in vivo SPF values confirmed a boost in SPF and an increase in water resistance for the formulation containing the polymer (VA/butyl maleate/isobornyl acrylate copolymer). Digital imaging of sunscreen films combined with image analysis and contact angle measurements suggest that the polymer conformation changes upon exposure to water. The polymer forms a protective barrier over the sunscreen film upon exposure to water, which explains the enhancement in water resistance. The polymeric film formed has a different refractive index than the sunscreen film. The change in refractive indices causes diffraction of incident light, thus increasing its pathlength, leading to an increase in SPF.

A new chemical approach to optimize the in vitro SPF method on the HD6 PMMA plate.

In a previous study, we demonstrated that control of the roughness of molded PMMA plates improves in vitro SPF reproducibility. However, in vitro/vivo deviations are still observed. Sunscreens show different behavior during spreading on the HD6 surface according to the formulation, resulting in a more or less homogenous distribution. The hydrophilic nature of HD6 appears to contribute significantly during spreading. Two different sunscreens offering a homogenous and non-homogenous distribution were investigated to check if the interfacial tension between product and substrate has a real influence on the spreading quality. Using microscopic observations, we attempted to correlate the in vitro SPF results with the product's spreading property. In order to reduce this interfacial tension, an HD6 pretreatment with an amphoteric surfactant, cocamidopropyl betain, was performed. In vitro SPF on "pretreated HD6" was examined using a cohort of 30 products. This pretreatment led to reliable results, demonstrating good association with the in vivo SPF.

New in vitro SPF Evaluation Method for Hydrophilic Sunscreen Samples.

A new method was developed for the in vitro sun protection factor (SPF) evaluation of sunscreen samples. A new type of substrate, a hydroxyalkyl cellulose-coated plate, was also prepared specifically for hydrophilic samples. This new substrate was required because hydrophilic samples would be unlikely to wet the surface of the standard cosmetic PMMA UV evaluation plate. A super-hydrophilic quartz plate was prepared by corona-discharge treatment before an aqueous solution of hydroxyalkyl cellulose was spread on it. A flat and uniform hydroxyalkyl cellulose film was subsequently formed through the evaporation of water. Special care was taken to inhibit the generation of spatial non-uniformity. Six hydrophilic sunscreen samples with in vivo SPF values of 56, 55, 52, 25, 15, and 4, were then applied to the prepared hydroxyalkyl cellulose-coated plate, as well as a super-hydrophilic quartz plate and a flat hydrophobic PMMA plate. The thicknesses of the applied layers were determined using a wheel-shaped wet film thickness gauge immediately after the application, and UV transmission was measured using an SPF analyzer. The value of in vitro SPF was calculated from the UV absorbance and the thickness of the layer. For two out of the six samples, PMMA plate could not be available, as the samples were unable to wet the PMMA surface. Relatively small differences were observed between the in vitro SPF values when the super-hydrophilic and hydroxyalkyl cellulose-coated plates were used. Samples exhibiting higher in vivo SPF were also associated with higher in vitro SPF values, although a linear relationship was not observed. In contrast to the super-hydrophilic plate whose half-life of the super-hydrophilicity is only approximately five days, the hydrophilicity of the hydroxyalkyl cellulose-coated plate scarcely varied during six months of storage. Finally, a simplified evaluation method was also proposed. The validity of the method was verified through a ring test where three researchers employed this method in different laboratories at three independent organizations.