Red Sensations Research Articles

Clinical Efficacy, Cosmetic Acceptability, and Local Tolerability of a New Formulation of Topical 5% Minoxidil without Propylene glycol: A 6-month, Multicentre, Real-life, Prospective, Assessor-Blinded Study in 196 Subjects with Hair Loss. The andldquo;NOMINALandrdquo; Trial

Background and trial objectives: A new propylene glycol (PG)-free 5% minoxidil (PG-Free-Mnx) lotion has been recently commercialized. Clinical efficacy and local tolerability have been, so far, documented in a limited number of patients. The aim of this study was to evaluate the clinical efficacy, cosmetic acceptability, and local tolerability of 6-month application of this new PG-Free Mnx lotion in a real-life situation. Materials and methods: The NOMINAL (NO-PG MINoxidil reAL life study) trial was performed in 22 out-patients Italian dermatology clinics. A total of 196 subjects of both sexes with a diagnosis of AGA/FAGA were enrolled in the trial, after their written informed consent. PG-Free-Mnx lotion was applied 1 ml twice daily for 6 months. Clinical efficacy was evaluated in an open fashion in all the enrolled subjects with a 5-grade scale score (from-2: severe worsening, to +2: very good improvement in comparison with baseline condition). In a subgroup of subjects (n=60) an assessor-blinded clinical efficacy evaluation has been also performed using high definition standardized and coded scalp global pictures at baseline, and after 6 months by an assessor unaware of the temporal sequence using a 3-grade score (from 0: no improvement to 3: very high improvement). Cosmetic acceptability evaluation was assessed using a 7-item questionnaire using a 10-point scale score, with score 1meaning not at all and score 10 meaning the worst possible condition. Cosmetic acceptability and clinical efficacy were evaluated after 12 and 24 weeks of treatment. Global tolerability, assessed at week 24, was evaluated with a 4-grade scale score (from -1: very low tolerability to +2: very good tolerability). Results: All but seven (3.6%) subjects concluded the study. Clinical efficacy scores (open evaluation) were 0.8 ± 0.7 and 1.0 ± 0.7 at week 12 and 24, respectively. Good or very good clinical response (score +1 or +2) at week 12 and week 24 was observed in 64% and 74% respectively of the subjects with a similar response in women (75%) and men (73%). Baseline severity of AGA/FAGA was inversely correlated with the clinical response with a better outcome in subjects with AGA type II in comparison with subjects with types III/ IV AGA. The clinical efficacy was confirmed by the assessor-blinded evaluation of the subgroup of 60 subjects’ pictures at baseline (clinical score at baseline: 0.2 ± 0.4 vs. 1.8 ± 0.7 after 6 months; p=0.0001; absolute mean difference: 1.6; 95% CI: 1.1 to 2.0). Cosmetic acceptability score mean values were always 7) burning, itching or redness sensations. Conclusion: This new PG-free lotion shows, in real-life conditions, a very good cosmetic acceptability and tolerability profile. Clinical efficacy, evaluated both in open and assessor-blinded fashions, was also documented, and it was in line with the available data of traditional Mnx formulations with propylene glycol.

The “NOMINAL” trial: Clinical efficacy, cosmetic acceptability, and local tolerability of topical 5% minoxidil lotion without propylene glycol: A 6-month, multicentre, real-life, prospective, assessor-blinded study in 196 subjects with hair loss.

Background and Trial Objectives: A new propylene glycol (PG)-free 5% minoxidil (Mnx) (PG-Free-Mnx) lotion has been recently commercialized. Clinical efficacy and local tolerability have been, so far, documented in a limited number of patients. The aim of this study was to evaluate the clinical efficacy, cosmetic acceptability, and local tolerability of 6-month application of this new PG-Free Mnx lotion in a real-life situation. Materials and Methods: The NOMINAL (NO-PG MINoxidil reAL life study) trial was performed in 22 out-patients Italian dermatology clinics. A total of 196 subjects of both sexes with a diagnosis of androgenic alopecia (AGA) and female androgenic alopecia (FAGA) were enrolled in the trial, after their written informed consent. PG-Free-Mnx lotion was applied 1 ml twice daily for 6 months. Clinical efficacy was evaluated in an open fashion in all the enrolled subjects with a 5-grade scale score (from-2: severe worsening, to +2: very good improvement in comparison with baseline condition). In a subgroup of subjects (n=60) an assessor-blinded clinical efficacy evaluation has been also performed using high definition standardized and coded scalp global pictures at baseline, and after 6 months by an assessor unaware of the temporal sequence using a 3-grade score (from 0: no improvement to 3: very high improvement). Cosmetic acceptability evaluation was assessed using a 7-item questionnaire using a 10-point scale score, with score 1 meaning not at all and score 10 meaning the worst possible condition. Cosmetic acceptability and clinical efficacy were evaluated after 12 and 24 weeks of treatment. Global tolerability, assessed at week 24, was evaluated with a 4-grade scale score (from -1: very low tolerability to +2: very good tolerability). Results: All but seven (3.6%) subjects concluded the study. Clinical efficacy scores (open evaluation) were 0.8±0.7 and 1.0±0.7 at week 12 and 24, respectively. Good or very good clinical response (score +1 or +2) at week 12 and week 24 was observed in 64% and 74% respectively of the subjects with a similar response in women (75%) and men (73%). Baseline severity of AGA/FAGA was inversely correlated with the clinical response with a better outcome in subjects with AGA type II in comparison with subjects with types III/IV AGA. The clinical efficacy was confirmed by the assessor-blinded evaluation of the subgroup of 60 subjects’ pictures at baseline (clinical score at baseline: 0.2±0.4 vs. 1.8±0.7 after 6 months; p=0.0001; absolute mean difference: 1.6; 95% CI: 1.1 to 2.0). Cosmetic acceptability score mean values were always <2 at each time-point evaluation, demonstrating good or very good acceptability. Global Tolerability score mean±SD value was 1.7±0.4 with 94% of the subjects reporting good or very good tolerability with no differences between men and women. No subjects reported severe or very severe (Tolerability score >7) burning, itching or redness sensations. Conclusions: This new PG-free lotion shows, in real-life conditions, a very good cosmetic acceptability and tolerability profile. Clinical efficacy, evaluated both in open and assessor-blinded fashions, was also documented, and it was in line with the available data of traditional Mnx formulations with propylene glycol.

Consciousness: Knowing the Unknowable

Consciousness:Knowing the Unknowable Nicholas Humphrey (bio) the author of the book of proverbs was selective in revealing what he did not know. "There are three things that are too wonderful for me, yea four that I know not: the way of an eagle in the air; the way of a serpent upon a rock; the way of a ship in the midst of the sea; and the way of a man with a maid" (Proverbs 30:18). Here I shall pass over the first three of these unknowables, and touch only briefly on the fourth. I want to address another unknowable phenomenon of nature that many philosophers and scientists continue to declare too wonderful for them: the way of conscious sensation. Imagine yourself looking at a bright red wall. The red sensation you are now experiencing is unknowable in two fundamental ways. The first is privacy. The sensation is yours alone. No one else can know "what it's like" for you, just as you could not know what it's like for anyone else. The second is explanatory opacity. There is no known explanation for how this conscious experience can arise from the physics of your brain. It was John Locke, in his Essay of 1690, who first explicitly brought the problem of privacy to scholarly attention. If the idea that a violet produced in one man's mind by his eyes were the same that a marigold produces in another man's, and vice versa … this could never be known: because one man's mind could not pass into another man's [End Page 157] body, to perceive what appearances were produced. ([1690] 1975, §II.xxxii.15) But Locke was articulating a problem that it hardly requires a great philosopher to recognize. We have probably played with versions of the problem since we were children, raising questions in the playground to tease and annoy our school friends. How do I know you see red like I do? How do I know if you're really in pain? What if your smells are like my sounds? Ha ha, there's no way of knowing! Ha ha, indeed. But the conundrum also has a worrying side to it. You may well remember how strange and even upsetting it was at first discovery: not merely an interesting tease, but potentially a serious challenge to the need to share and understand. If we cannot even tell what seeing red is like for someone else, what can we tell? Imagine. We are walking together in the woods after the rain, dappled sunshine filters through the dripping leaves, a blackbird sings, and the scent of honeysuckle permeates the rich air. It may be that shared moments like this are needed to give meaning to our lives. What then when we realize how little we are truly sharing, that, if truth be told, each of us is merely coloring in the other's consciousness as if it were our own? Still, what is to be done? Realizing, early on, that the privacy of consciousness is a brute fact about the human condition, most of us as we grew up will have put the problem aside. Sometimes philosophical doubts, however cogent in theory, are hardly worth worrying about in practice. Samuel Johnson famously dismissed the Idealist suggestion that the external world is nothing other than an idea in his own head by kicking a stone and declaring, "I refute it thus." Whatever our first anxieties about the limits to our knowledge, our adult selves will probably want to brush them aside with a confident, plain-man's assertion that, in practice, we know all we need to know. As it happens, Locke himself unexpectedly pulled back from the brink of his own thought experiment about colors. In a passage, little known even to scholars, that follows the famous one quoted above, he wrote: [End Page 158] I am nevertheless very apt to think that the sensible ideas produced by any object in different men's minds, are indiscernibly alike. For which opinion there might be many reasons offered: but being besides my present business, I shall not trouble my reader with them: but only mind...

A MODEL FOR PREDICTING DIAMETER OF 'RED SENSATION' PEARS

A MODEL FOR PREDICTING DIAMETER OF 'RED SENSATION' PEARS

Safe and effective treatment of problem scars with the purely thermal non‐ablative Er:YAG laser scar mode

Introduction: Traumatic events as well as surgery can cause a large variety of scars, which are often a major psychological concern to patients. Moreover, patients often report itching or burning sensations as well as pain. We investigated the efficacy of purely non‐ablative laser therapy in order to improve the appearance and quality of these scars. Methods: A total of 62 patients with problem scars were enrolled in the study. The purely thermal, non‐ablative scar mode of an Er:YAG laser (BURANE XL; Wavelight AG, Erlangen, Germany) was used. One to six treatment sessions were performed. The improvement of scar redness, scar flatness, scar quality, itching and burning sensations as well as pain and patient satisfaction were evaluated. Results: The overall scar quality improved in 93% of patients. Similarly, the flatness improved in 89% of scars, itching sensation in 79% and burning sensation in 86% of patients. In 91% of scars a decrease of scar redness was seen and all painful scars showed a pain reduction. Average patient satisfaction was 7.4 on a 10‐point scale. Sixty‐one patients would recommend the therapy to another person. Side effects were limited to transient erythema and oedema. Conclusion: The high success rate combined with the low side‐effects resulted in high patient satisfaction. Post‐traumatic or post‐surgical scars can safely and effectively be treated by the thermal scar mode of the Er:YAG laser used.

Is Binocular Fusion of “Cortical Yellow” an Illusion, Contingent upon Abstraction of Coherent Sensory Information from the Two Eyes?

This research on the binocular fusion of phenomenal yellow, given red-filtered flashes of light in one eye and green-filtered flashes of light in the other, directly compared the effects of wider-bandwidth and narrow-bandwidth filtering. 20 male college students with normal stereopsis, Mage = 19.3 yr., SD = 2.2, were tested for the binocular perception of flashing yellow sensations given wider-bandwidth versus narrow-bandwidth filtering of light flashes which, monocularly, were experienced as red sensations in one eye and as green sensations in the other. When 3 wide-bandwidth tests for binocular yellow fusion were alternated with 3 narrow-bandwidth tests, simultaneous flashes of red-filtered light in one eye and green-filtered light in the other were binocularly perceived as yellowish on 25% of the wide-bandwidth tests (SD = 40%)--as yellow on 8% of the tests, orange on 12% of the tests, yellow-green on 5% of the tests-and were binocularly perceived as yellowish on 0% of the narrow-bandwidth tests. When wider-bandwidth and narrow-bandwidth testing were separated spatially and conducted contemporaneously, the red-filtered flashes in one eye and green-filtered flashes in the other were binocularly experienced as yellowish sensations by 80% of all participants under wider-bandwidth conditions--as yellow by 55%, orange by 10%, yellow-green by 15%--and as yellowish sensations by 0% of the participants under narrow-bandwidth conditions.

Different sensations from cones with the same photopigment

We used adaptive optics to study color fluctuation in the appearance of tiny flashes of light. For five subjects, near threshold, monochromatic stimuli with full widths at half maximum of 1/3 arcmin were delivered throughout a patch of retina near 1 deg in which we also determined the locations of L, M, and S cones. Subjects reported a wide variety of color sensations, even for long-wavelength stimuli, and all subjects reported blue or purple sensations at wavelengths for which S cones are insensitive. Subjects with more L cones reported more red sensations, and those with more M cones tended to report more green sensations. White responses increased linearly with the asymmetry in L to M cone ratio. The diversity in the color response could not be completely explained by combined L and M cone excitation, implying that photoreceptors within the same class can elicit more than one color sensation.

Emotionally Directing Visual Sensations: II. Lowering the Threshold for Tinted Percepts

In Experiment 1, while ranking the similarity of paired colors, 126 subjects generated feelings of anger and 115 subjects generated feelings of sadness. Paired reds became more similar during anger, and paired blues became more similar during sadness. This initial finding suggests that, from a first-person perspective, the phenomenal world looks redder during anger and bluer during sadness. On each trial in Experiment 2, while trying to discriminate whether a monochromatic face was liminally presented at the top or bottom of a screen, 30 subjects generated either anger or sadness. Better than chance discriminations were obtained only for the localization of red faces during anger and the localization of blue faces during sadness. This latter finding suggests that, from a third-person perspective, the neural threshold for red sensations is lowered by anger, and the neural threshold for blue sensations is lowered by sadness.

Four Spectral Channels for Natural Imaging of Scene Colors

Ideal imaging channels should have the same spectral sensitivities of scene recording as vision channels and independently control the primary color sensations of eye. The trichromatic colorimetry is not helpful with its unreal primaries (XYZ) or alternating RGB color matching functions, which are little suggestive of non-negative channel sensitivities. Although the natural color space is formed by two alternating blue-yellow and green-red color axes, the nonnegative imaging space has to use an independent channel to render each of the four visual half-axes. The short-wave and long-wave channels in 56 modern photographic systems closely simulate their opponency against the yellow and bluish-green vision channels, which are roughly presented with a single middle-wave channel. The channel sensitivities are delimited by the neutral points of rod and cone. The necessary spectral overlaps of non-opponent channels are absent, thus decreasing the saturation of mixed colors. Positive dyes closely simulate the primary blue and red sensations, but the yellow and bluish-green ones are roughly replaced with an averaged yellowish-green color. An accurate rendering of natural saturation, metamery, the problematic bluish-green, purple-red, and low-illumination colors requires division of the middle-wave imaging channel into two separate ones. A spectral specification for the natural four-channel imaging is proposed, basing on the data of physiological, psychological, and medical studies of color vision.

How sensations get their names

There are normally four elements in any perceptual experience: a sensation or sensations, some cognitive state or states (i.e., belief states), an affective state or states (liking/disliking, among others), and some overt behavioral state or states.' The traditional theory in philosophy has been that of these four states the most important is the sensation. It is the having of a certain kind of sensation which determines what kind of perceptual experience we are undergoing. We determine what kind of sensation state we are having simply by having it, reidentify it when it recurs, and name the associated perceptual state accordingly. It is because we have visual sensations that we say we see. It is because blind people don't have these sensations that we say they don't see. It is because auditory sensations are so different from visual ones and both are so different from tactile ones, and so forth, that we say we have five (or more) kinds of perceptual experiences. And it is because the visual sensation of red is so different from the visual sensation of blue that we say one is the experience of red, the other of blue, and the like. It is because we have red sensations when confronted by certain objects that we ascribe the property "red" to those objects. Perceiving, according to this traditional theory, is essentially a sensory state. Understanding the sensation and its phenomenal properties is essential to understanding perception. I believe this picture of perceptual experiences to be quite wrong. I will argue that sensations are the least important element in perceptual experiences; that far from the nature of the sensation determining the nature of the experience, it is the nature of the experience, itself determined otherwise, that determines how we categorize the sensation: that rather than naming the sensation as a visual experience, say, simply by having it, we first name the perceptual experience, and insofar as sensations have names, they take them from the sorts of perceptual experi-

Additivity failure of chromatic valence in the opponent-color theory

The additivity of flicker responses produced by two different wavelengths λ1 and λ2 was investigated for five adapting levels of 560 nm by the summation-index method. A summation-index value of σ of 0.30 was obtained for all conditions employed, confirming the linear property of the achromatic channel. The additivity of unique chromatic responses, red, yellow, green, and blue, was also investigated with the same method. In this case the wavelengths λ1 and λ2 were chosen in a spectral region to produce one of the four unique colors and the summation index was measured for the color with the cancellation method. A summation index of 0.30 was found for the green and blue sensations and also for the red sensation if both stimuli were from the same spectral region. A slight additivity failure of the enhancement type was found for pairs λ1 and λ2 λ1 was in the short-wavelength region while λ2 was in the long-wavelength region. An additivity failure of the same type was found for the yellow chromatic sensation when λ2 was 607 nm and λ1 was 570, 550, or 533 nm, the last combination giving a summation index of as much as 0.64. The results imply the existence of two different cones whose responses do not add linearly to yield the yellow sensation.

Additivity of opponent chromatic valence

The additivity of chromatic valences that were produced by two different wavelengths λ 1 and λ 2 was investigated for four chromatic sensations, red, green, yellow, and blue, by the summation index method. Linear additivity was found for the green and the blue chromatic valence giving the summation index of 0.30. The linear additivity was also found for the red sensation if both stimuli were in the same region of long wavelengths or of short wavelengths. A slight additivity failure of the enhancement type was, however, found for λ 1 and λ 2 pairs when λ 1 was chosen in the short wavelength region while λ 2 in the long wavelength region, respectively. The additivity failure of the same type was found for the yellow chromatic valence for two subjects when λ 1 was 607 nm and λ 2 was 570, 550, and 553 nm, the last combination giving a summation index of as much as 0.64. The results may imply the existence of two different cones whose responses do not add linearly to yield the yellow sensation.

Anomalous pigments in the eyes of the red-green colour blind.

LORD RAYLEIGH noticed that his brother-in-law, Lord Balfour, had abnormal vision and he devised the Rayleigh match to examine it. In rather similar circumstances many years before, Clerk Maxwell used the Maxwell colour triangle to prove that his father-in-law lacked the fundamental red sensation.

Drugs and Personality

In a previous paper in this series, a brief discussion has been given of the theoretical reasons for anticipating that depressant drugs would shorten the perceptual after-effects of visual stimuli, and stimulant drugs would lengthen these effects. The present paper is concerned with a related type of prediction, also concerned with certain visual after-effects. The phenomenon in question was first observed by Bidwell; it has not received much study, unfortunately, in spite of its great theoretical interest. The phenomenon is simply this. If a beam of red light (the primary stimulus, or Sp) is thrown into the eye of a person having normal colour vision, that person will report a red sensation, followed after the extinction of the light source by a series of after-images, usually in the complementary colour. The theory governing the appearance of the after-image is conventionally a photochemical one; the Sp produces certain effects in the retina which are opposite in direction for complementary colours and which are reversed when the Sp ceases to act on the retina. This reversal is perceived as the complementary after-image. Bidwell discovered that when the Sp is shown only for a relatively short period of time, say 20 milliseconds, and is immediately followed by a neutral stimulus, such as a beam of white light, then the S is not perceived at all, but only the complementary after-image. In other words, a red stimulus is perceived as green, a green stimulus as red. It is this perception of a non-existent stimulus which caused the phenomenon to be of such interest to psychologists.

Reflex Visual Sensations and Anomalous Trichromatism

SYNOPSISSec. I. Introduction.—This contains a brief summary of the principle of reflex visual sensations as discovered by Allen. The author, whose vision is somewhat abnormal, sets out to determine the character of these reflexes for his abnormal vision.Sec. II. Apparatus and Methods of Measurement.—All experiments were performed in a daylight room, using the critical frequency of flicker method. The results, which are quantitative, were obtained by making measurements on pure spectral colors.Sec. III. Normal Curves.—Abnormal vision is shown by the character of the persistency curve, taken under normal conditions of daylight adaptation. The type of curve, which was found to be the same for both eyes, is compared with one for normal vision and one for partial red color blindness.Sec. IV. Reflex Curves.—This contains the descriptions and results of experiments carried out by fatiguing the left eye and making measurements of the changes in the visual response of the right to light from the different parts of the spectrum.The nature of any change in the response was always found to be an enhancement of brightness of the affected colors. Red and green were found to be more susceptible to this reflex enhancement than the violet. Certain colors, .660μ, .505μ, .425μ, and the entire region .520μ to .480μ, showed no reflex transferred to the other eye. The magnitude of the reflex was greatest for fatiguing colors near the ends of the spectrum. The effect of dark adaptation was also transferred to the other eye similarly to fatigue.Sec. V. Fatigue Curves.—This contains descriptions and results of experiments in which the measurements were made on the fatigued eye, the other being always in daylight adaptation.It was found that the red sensation was very difficult to fatigue, but very susceptible to enhancement. The violet showed the reverse character, and the green an intermediate position. No effect was obtained for fatigue colors, .665μ, .589μ, .570μ, and only a small effect for .520μ. The effects of darkness and strong white light are very similar, both showing fatigue characteristics.Sec. VI. The Theoretical Considerations.—The experimental results show that every ray of light produces both a direct and a reflex effect upon all three fundamental sensations, which are shown to be red, green, and violet. The author’s type of color vision is shown to be that of an anomalous trichromat, and experimental evidence is applied to give a fuller meaning to the phenomenon as well as to explain it. The principle of visual reflexes is applied to the Young-Helmholtz and Hering theories to show that the two can no longer be regarded as rival theories, but can be harmonized by this principle.

Colour-blindness and the trichromatic theory of colour vision. Part IV. -Incomplete colour-blindness

A Simple Test .—In Parts II and III of this series of papers I have indicated several methods of giving a quantitative value to the amount of green or red sensation which exists in the incomplete green- or red-blind eye as compared with the normal eye. I need not summarise what has already appeared at recent dates in the ‘Proceedings’ of the Royal Society, but I will at once explain a very simple test which gives quantitative measures of the sensations in incomplete colour-blindness. In my last paper of the series a table is given of the luminosity of the arc spectrum and the percentage composition of the tabulated rays of the spectrum, and from the same table the amount of white which exists in these several rays can readily be calculated. Owing to change in hue which white causes in a mixture of a pure red with a green ray I pointed out that the match of the D line by two such rays is open to error, not considerable perhaps, but still appreciable. In my communication “On the Change of Hue of Spectrum Colours by Dilution with White Light, it was shown that the change in hue at the point where the two curves of red and green sensations cut when their areas are made equal is nil . For reasons given later it may also be mentioned that a ray at this point when mixed with a blue where the same red and green sensation curves cut, will, with proper adjustment of the widths of the slits, match the white of the reflected beam of the arc light. The same happens for any other source of light if the curves of equal areas are calculated for such a light. The position of the point of intersection in the yellow part of the spectrum varies with the kind of light forming the spectrum. Looking at the table it will be seen that from S. S. N. 50 to the extreme red there is no blue sensation present in measurable quantities. Suppose that in a beam of the arc spectrum a cell containing a saturated solution of potassium chromate of (say) ¾ inch in thickness is placed; the beam becomes yellow with very little blue present. If a slit is caused to traverse the spectrum in the colour patch apparatus a position will be found for it which exactly matches the hue of the white light which passes through the chromate solution, and will be at S. S. N. 49·6 or λ 5828 to the normal eye. This, like other rays, contains a fixed ratio of green to red sensations, but no blue which is measurable. Making the red sensation unity it will be found that the green sensation present is 0·385. A table of the ratio of red to green sensation (making red unity) for the standard spectrum scale is annexed, as is also a table of wave-lengths with the like ratios:—

Societies and Academies

Societies and Academies

Colour-blindness and the trichromatic theory of colour vision. Part II.—incomplete red or green blindness

In Part I of this subject I treated of complete colour-blindness in its relation to the trichromatic theory of colour vision. In this communication, which is a continuation of that published, I deal with incomplete colour­-blindness and its relation to the same theory. The number of cases of incomplete red or green blindness is larger than those where the colour­-blindness is complete. In cases of incomplete colour-blindness so far as they have come under my examination the sensation curves of the red and green sensations are similar (in a mathematical sense) to those existing in normal vision, that is to say, if in the normal (say) red curve an ordinate of one colour indicates a perception of “ a ” red, and for the incomplete red-blind a perception of “ b ” red, then in any other position in the spectrum the proportion of normal to incomplete red-blindness is as a : b . This fact leads to a far-reaching conclusion. It tells us that the place of maximum luminosity travels in the case of red-blindness from Standard Scale No. (S. S. N.) 50 to S. S. N. 46. A reference to Table I will show why such travelling of maximum luminosity takes place. To take two examples, a table (Table II) and diagram of luminosity curves for eyes which only perceive one-third of the red sensation and one-third of the green sensation is given. In the first the maximum is closely at S. S. N. 48 ( λ 5720), and in the second at S. S. N. 51 ( λ 5922). The maximum at S. S. N. 49 ( λ 5873) is when the red sensation is about two-thirds of the normal, and at S. S. N. (47) ( λ 5658) when it is about one-tenth of the normal, at S. S. N. 46 ( λ 5600) when there is no red sensation. In the green-blind when there is no green sensation the maximum is closely at S. S. N. 52 ( λ 6000). By observing the position of maximum luminosity we can form an approximate diagnosis of the amount of the defect and as to the sensation in which the defect exists.