Three-tier testing approach for optimal ocular tolerance sunscreen

Figures & data

Figure 1. Time response curve graphs of the SCFW and the positive control. PC: positive control; SCFW: sunscreen fusion water.

Table 1. Criteria for a product to be classified as stinging to the eye, using the NociOcular Assay for surfactants.

Test parameter	Cut-off level
Emax (% of capsaicin positive control response)	≥24%
EC50 (concentration inducing 50% effect of Emax) (w/v)	≤0.03% or ≤0.3 mg/mL
Effect at the concentration 0.032%^a	≥22%

Notes: These testing criteria are for determining sting potential for surfactants and are not applicable for sunscreens. Sunscreens are evaluated based only on TRPV1 Specific activity.

^a effect at 0.032 = percentage calcium influx response observed in the wells without capsazepine.

Table 2. Scales for objective ophthalmological evaluation in ocular instillation clinical study.

Lacrimation	0 = None
	1 = Excessive wetness
	2 = A few formed tears
	3 = Intensive lacrimation
Irritation: bulbar conjunctiva	0 = None
	1 = Mildly pink
	2 = Moderately pink, some dilation
	3 = Intense red vessels, dilated
Irritation: palpebral conjunctiva	0 = None
	1 = Mildly pink
	2 = Moderately pink
	3 = Cherry to deep red
Irritation: scleral vessels	0 = None
	1 = Slight dilation
	2 = Moderate dilation
	3 = Intense dilation

Figure 2. Ca²⁺ influx in response to capsaicin for SCFW and SC with or without capsazepine. SC: oil-in-water sunscreen; SCFW: sunscreen fusion water.

Table 3. ET₅₀ values determined with EpiOcular time-to-toxicity (ET-50) test.

Treatment	Exposure times	ET50	Classification
SCFW	4, 8,16 and 24 hours	>24 hours	Not irritant
Deionized water (negative control)	15 minutes, 4, 8, and 24 hours	Not applicable	Not applicable
0.3% Triton-X-100 (positive control)	15 and 45 minutes	27.1 minutes	Irritant

Notes: The negative control was tested from 15 min to 24 h and represents 100% viability. Each exposure time was tested in duplicate tissues.

ET₅₀: exposure time required to reduce viability by 50% of the negative control; SCFW, sunscreen fusion water.

Table 4. Results of NociOcular Assay.

Treatment	EC50 (%)	Emax (% of positive control)	Effect at 0.032%	TRPV1 Activity
SCFW	0.08675	28.24	NC	Absent, Non-stinger
SC	0.00554	51.08	NC	Present, Potential Stinger

Notes: The negative (or solvent) control and the positive control (100 nM capsaicin) were dosed on each plate along with a test article and represent 0% to 100% Effect. Effect at the concentration 0.032% was considered not applicable and therefore not calculated.

EC₅₀: Ca²⁺ concentration yielding 50% of the maximum capsaicin response, Emax, maximal Ca²⁺ specific response of the test substance; NC: not calculated; SC: oil-in-water sunscreen; SCFW: sunscreen fusion water; TRPV1: transient receptor potential cation channel subfamily V member 1 (capsaicin receptor).

Figure 3. Ophthalmological evaluation scores at each time point. Values are mean (SEM); SCFW, sunscreen Fusion Water. SEM: standard error of mean.

Table 5. Demographic characteristics of ocular instillation study subjects.

Participant characteristics
Sex, n (%)	25
Male	10 (40%)
Female	15 (60%)
Age, years, mean ± SD	58.8 ± 13.6
Min	20
Max	75

Table 6. Ophthalmological evaluation scores represented as means (SD) of individual scores.

	Mean Score	SCFW	10% baby shampoo	p Value
Lacrimation	Baseline^a n = 25	0.0 (0.0)	0.0 (0.0)	1,000^n.s
	30 seconds^a n = 25	1.6 (0.8)	1.6 (0.7)	0.655^n.s
	15 minutes^a n = 25	0.5 (0.5)	0.4 (0.5)	0.655^n.s
	1 hour^a n = 25	0.3 (0.5)	0.1 (0.3)	0.025
	2 hours^a n = 10	0.3 (0.5)	0.0 (0.0)	0.083^n.s
	Sum scores^b	2.5 (1.4)	2.1 (1.0)	0.134^n.s.
Bulbar conjunctiva	Baseline^a n = 25	0.2 (0.4)	0.2 (0.4)	1000^n.s
	30 seconds^a n = 25	1.5 (0.6)	1.6 (0.7)	0.763^n.s
	15 minutes^a n = 25	0.7 (0.7)	1.0 (0.8)	0.090^n.s
	1 hour^a n = 25	0.8 (0.8)	0.3 (0.5)	0.013
	2 hours^a n = 10	0.6 (0.8)	0.2 (0.4)	0.046
	Sum scores^b	3.2 (1.9)	2.9 (1.8)	0.427^n.s.
Palpebral conjunctiva^a	Baseline^a n = 25	0.0 (0.0)	0.0 (0.0)	1000^n.s
	30 seconds^a n = 25	0.8 (0.6)	0.8 (0.6)	1,000^n.s
	15 minutes^a n = 25	0.5 (0.7)	0.8 (0.7)	0.033
	1 hour^a n = 25	0.5 (0.7)	0.2 (0.5)	0.020
	2 hours^a n = 10	0.5 (0.7)	0.2 (0.4)	0.083^n.s
	Sum scores^b	2.0 (1.9)	1.9 (1.7)	0.701^n.s.
Scleral vessels	Baseline^a n = 25	0.0 (0.0)	0.0 (0.0)	1,000^n.s
	30 seconds^a n = 25	0.0 (0.0)	0.0 (0.0)	1,000^n.s
	15 minutes^a n = 25	0.1 (0.3)	0.2 (0.5)	0.083^n.s
	1 hour^a n = 25	0.2 (0.4)	0.0 (0.2)	0.083^n.s
	2 hours^a n = 10	0.2 (0.4)	0.0 (0.0)	0.157^n.s
	Sum scores^b	0.3 (0.7)	0.2 (0.6)	0.688^n.s.

^a 0 = lowest possible score, 3 = highest possible score.

^b 0 = lowest possible total score, 12 = highest possible total score;.

n.s ^. not significant, bold: significant.

SCFW: sunscreen fusion water; SD: standard deviation.

Figure 4. Subjective evaluation scores at each time point. SCFW: sunscreen fusion water.

Table 7. Subjective assessment – Mean scores (SD) per assessment time and sum scores for prickling, tingling, burning, stinging, itching.

Mean score	SCFW	10% baby shampoo	p Value
30 seconds^a n = 25	1.8 (1.0)	1.9 (1.1)	0.479
15 minutes^a n = 25	1.2 (0.7)	1.0 (0.7)	0.340
1 hour^a n = 25	1.0 (0.8)	0.2 (0.5)	0.003
2 hours^a n = 10	0.6 (0.5)	0.0 (0.0)	0.014
Sum scores^b	4.2 (2.5)	3.1 (1.9)	0.052^n.s

^a 0 = lowest possible score, 3 = highest possible score.

^b 0 = lowest possible total score, 12 = highest possible total score;

n.s ^. not significant.

SCFW: sun screen fusion water; SD: standard deviation.