Volume 16, Number 2
February 2010

A review of home phototherapy for psoriasis�
Bridgit V Nolan1, Brad A Yentzer MD2, Steven R Feldman MD PhD2
Dermatology Online Journal 16 (2): 1

Abstract

Background: Phototherapy is a mainstay in the treatment of psoriasis and other photoresponsive dermatoses and home phototherapy has broadened therapeutic options.

Purpose: To describe the history of home phototherapy, the technological advances in the safety and efficacy of the equipment available, and the associated issues of cost, convenience, adherence, and quality of life.

Methods: We conducted a literature review of home phototherapy, broad-band UVB, narrow-band UVB, and PUVA phototherapy using PUBMED. A Google search of home phototherapy equipment and technology was also undertaken.

Results: Technological advances in home phototherapy equipment have allowed for more treatment options and improvements in safety and efficacy. One randomized, controlled trial found results comparable to office-based phototherapy. Home phototherapy is convenient, cost-effective, and associated with better quality of life compared to outpatient phototherapy treatment. One trial found that adherence to home phototherapy regimens was better than to oral retinoids.

Conclusions: Home phototherapy is a well-tolerated, efficacious, economical and patient friendly therapeutic option. Advantages of home phototherapy include improved quality of life, greater convenience, lower cost, and less time lost from work and social activities. Dermatologists should strongly consider home phototherapy as a first-line treatment option for appropriately selected psoriasis patients.

UVA (PUVA) Comparison with UVB Narrow Band

Comparisons using the split-body approach have been made to assess the relative efficacy of trimethylpsoralen bath PUVA and NB-UVB in patients with chronic plaque psoriasis [21, 22]. The decrease in Psoriasis Area and Severity Index (PASI) score was greater on the NB-UVB side compared with topical PUVA, and this difference occurred earlier during the course of treatment on the NB-UVB treated side. Additionally, NB-UVB treatment was associated with fewer side effects and better tolerability. These results suggest that NB-UVB is more effective, efficient, and better tolerated compared to topical PUVA in the treatment of chronic plaque psoriasis psoriasis [22]. Comparisons of PUVA with oral psoralen versus NB-UVB phototherapy demonstrate that PUVA is more effective and efficient in clearing and maintaining remission in patients with chronic plaque psoriasis (n=93). Clearance was achieved in 84 percent of patients treated with PUVA, after an average of 17 treatments compared to NB-UVB treatment, which resulted in clearance for 65 percent of patients after an average of 28.5 sessions (n=93). Remission at six months was 68 percent in the PUVA group versus 35 percent in the NB-UVB group. However, the side effects associated with PUVA were greater, with 49 percent reporting erythema in the PUVA group compared to only 22 percent in patients undergoing NB-UVB [23]. It should also be noted that this study used twice-weekly dosing with NB-UVB versus the standard 3-5 times per week of UVB phototherapy. Because PUVA is also associated with potential systemic side effects (erythema, pruritus, nausea, ocular damage, and increased risk of skin cancer) as well as death from accidental overexposure, it is generally not recommended as an option for home phototherapy.

Home Phototherapy

Over the years, there have been numerous studies to determine the efficacy of home phototherapy, including a simple evaluation of home phototherapy with and without the concurrent use of topical treatment, home phototherapy in addition to systemic therapy, and a pragmatic, randomized controlled trial comparing home versus outpatient phototherapy (Table 1). The efficacy of home phototherapy was demonstrated by complete remission of psoriatic lesions in 20 of 28 (71.4%) patients with long-standing, severe psoriasis after 45 exposures to high-dose BB-UVB home phototherapy as a sole therapeutic intervention. Of note, the subjects underwent MED determination and were closely monitored for response to treatment with weekly visits. This arrangement constitutes more supervision than many home phototherapy regimens. The need for adequate monitoring of response to treatment and incidences of adverse events is a major consideration in prescribing home phototherapy as a therapeutic intervention. This consideration underscores the importance of using home phototherapy units equipped with prescription controlled timers to limit the number of treatments between office visits. Additionally, patients with extensive, recalcitrant psoriasis showed clearance of psoriatic lesions in 55 of 56 (98.2%) patients after 8 weeks of BB-UVB treatment in suberythrogenic dose with concurrent use of topical coal tar [28]. In patients with patch and early plaque stage mycosis fungoides, home phototherapy consisting of erythemogenic doses of UVB resulted in clinical and histopathological clearance and prolonged remission in 7 of 31 patients. A comparison of the efficacy of high output UVB at home and at physician offices in patients with recalcitrant hand eczema demonstrated much improvement in 7 of 11 (63.6%) patients in the home group and 11 of 13 (84.6%) patients in the outpatient group [30]. Eighteen of 23 psoriasis patients demonstrated complete clearance with an additional 3 showing marked improvement with the use of NB-UVB. NB-UVB was also shown to be effective in a variety of other photoresponsive dermatoses (Table 1). Home phototherapy in conjunction with oral acitretin for 12 weeks in patients with moderate-to-severe plaque psoriasis reduced PASI score by 22 percent and was clinically significant as demonstrated by an associated improvement in quality of life (as measured by DLQI).

Home phototherapy had similar efficacy to outpatient phototherapy in a large, randomized, well-controlled trial (n=195). For patients undergoing home phototherapy, 82 percent and 70 percent reached Self-Administered Psoriasis Area and Severity Index (SAPASI) 50 and PASI 50, respectively, compared with 79 percent and 73 percent of the patients receiving outpatient treatment. Additionally, the median SAPASI and PASI scores for patients receiving home phototherapy decreased by 82 percent and 74 percent, respectively, compared with 79 percent and 70 percent decreases in the outpatient group. The overall treatment effect, as assessed by the mean reduction in PSAI and SAPASI, and the increase in quality of life was significant and similar between the two groups. As used in this study, home phototherapy was similar in efficacy to standard outpatient phototherapy.

Safety of home phototherapy devices

Adverse effects associated with phototherapy include both acute adverse effects and cumulative, dose-related effects that occur with prolonged use. Early adverse effects associated with BB- and NB-UVB phototherapy are typically limited to erythema and drying of the skin, with maximal erythema occurring between 8 and 24 hours following exposure. Blistering represents a severe acute adverse event more commonly associated with exposure to BB-UVB phototherapy compared to NB-UVB, due to the lower erythemogenicity of NB-UVB. Concerns about the possible increased risk of acute adverse events in the home setting has raised questions about the appropriateness and safety of home phototherapy. Side effects of home phototherapy are common with 44 percent of patients reporting adverse effects, but the reported side effects are mild and include erythema (36%), blisters (1%), pruritus (8%), and dryness (1%). In a comparison to home versus outpatient phototherapy, there was mild erythema in 87 percent of subjects, burning sensation in 56 percent, severe erythema in 36 percent, and blistering in 6 percent, with no difference in incidence of acute adverse events between the two groups. Thus, acute adverse effects appear to be mild and well-tolerated, with severe reactions occurring in low incidence. Late adverse effects result from the cumulative UVB dose, which leads to aesthetic changes, including premature aging (photoaging), wrinkling, and leathery appearance, increased fragility of the skin, and increased risk of photocarginogenesis. Such late adverse effects correlate directly with the total cumulative dose and the incidence of acute adverse events. Data investigating the carcinogenetic risk associated with exposure to BB- versus NB-UVB do not demonstrate a significant difference. Because photocarginogenesis is directly related to the cumulative dose of UV light and to the incidence of acute adverse events, the presumed long-term risk associated with home phototherapy may be similar to that associated with outpatient treatment. Whereas there are good data demonstrating the long-term safety of physician-administered phototherapy, no such data are available for home treatment. However, the existing data demonstrates no differences in acute adverse events or total cumulative ultraviolet dose and there are no data suggesting that home phototherapy is less safe than standard outpatient treatment [33].

Improved technology has allowed for the evolution of safer home phototherapy devices. Innovative safety features in newer units include a key-locked ON/OFF switch to prevent unauthorized use, a built-in controlled prescription timer (CPT), and a failsafe feature that disables the unit in the event of malfunction [38-45]. The controlled prescription timer (CPT) ensures that the equipment can only be used for a certain number of treatments as prescribed by the doctor between office visits. Such innovations make phototherapy safer and more appropriate for home use by allowing greater monitoring for appropriate response to treatment and for incidence of adverse events. Additionally, these features decrease the possibility of unauthorized use or inappropriate use and thus reduce physician and patient worry about potential side-effects, lack of follow up, or abuse.

 Advantages of home phototherapy

The advantages of home phototherapy to both doctor and patient are numerous and include convenience, lower cost, better adherence to treatment, and improved quality of life [55]. In terms of treatment effectiveness, adherence is one of the most important factors in determining clinical outcomes. Patients’ adherence to home phototherapy regimens is high and may be even better than to oral psoriasis treatment [32]. Furthermore, improved quality of life, which is attributable to a certain form of treatment, is likely to foster better adherence to that treatment.

Convenience

Repeated journeys to the hospital or outpatient offices for phototherapy pose an obvious inconvenience and expense. Geographic, work, and economic constraints compound the difficulty for patients to maintain an adequate treatment schedule. Treatment plans which are too complicated, costly, or time-consuming may increase the burden of chronic disease. Convenience factors played a major role in patients’ decisions regarding mode of treatment and adherence to treatment. In a survey of patients undergoing home phototherapy, forty percent of users identified “time” as their reason for selecting home phototherapy and an additional seventeen percent chose it due to “difficulty with work schedule”. Other reasons relating to convenience included “convenience of being at home” and “moving from the city” [4]. In another survey, 42 percent of patients undergoing outpatient phototherapy described this method as “inconvenient” and 75 percent indicated that home phototherapy would be helpful. The importance of convenience factors and the relationship between convenience and adherence has been emphasized in the dermatology literature. Additionally, technological advances in equipment design have made home phototherapy units more convenient. Home phototherapy units now operate on standard house electrical current. Many have convenience features, such as casters, which allow for easy moving; adjustable wheels that ease movement on any type of floor surface; and wings or doors, which can be closed or folded away for easy storage (Table 2).

In tanning bed antiquity, the UVB content was much higher. Today, in the USA, the FDA has regulated that the UVB content in tanning beds must be very low! Because of regulations, tanning beds produce only 4.2% to 6.5% UVB in the USA and typically 1% to 3% in Europe. To read the US FDA Regulations <Click Here>. The level of UVB radiation is in the following statement “Performance requirements–(1) Irradiance ratio limits. For each sunlamp product and ultraviolet lamp, the ratio of the irradiance within the wavelength range of greater than 200 nanometers through 260 nanometers to the irradiance within the wavelength range of greater than 260 nanometers through 320 nanometers may not exceed 0.003 at any distance and direction from the product or lamp. UVB is commonly defined as 280 to 320 nanometers.

Tanning Salons can be a risk for the typical consumer as the output from these beds can vary greatly from bed to bed and treatment/tanning times must be adjusted based on lamp power. When a bed is re-lamped and you are not told then a sunburn is very likely.

UVA wavelengths pass through the epidermis to the hypodermis Click on the image for a link to this photo's source.

Read this article http://www.pnas.org/content/101/14/4954.full which seems to indicate that UVA may be more dangerous than UVB. This is a complicated subject but it does appear that it is UVA that contributes to premature skin aging and is more likely to cause cancers of the skin.

UNDERSTANDING UV RAYS
“Most everyone is aware of the risks associated with UVB exposure, however there are real risks associated with UVA exposure including skin aging, DNA destruction and even skin cancer. Protecting your skin from UVA rays is just as important as protecting yourself against UVB rays.”  – A quote by Dr. Henry Lim, Vice President-Elect, American Academy of Dermatology and Chairman of Dermatology, Henry Ford Hospital, Detroit, MI.

Here’s another posting at this blog on the diferences twixt UVA and UVB. See PUVA vs UVB NARROWBAND.

Don’t be fooled by the non-medical advice of a tanning salon owner! Check with your dermatologist.

Here’s a link to an article on Vitamin D Deficiency that you might want to read.

Research has shown that it is the UV (Ultraviolet) portion of the spectrum that helps the body create Vitamin D . This is one of the known benefits of UV. The use of sun-screens, hiding indoors from the sun as we worry about skin cancers and the like is now perhaps one of the causes of Vitamin D deficiencies in some of our population.

Dr. Michael F. Holick, author of The UV Advantage is one of the world’s experts on Vitamin D runs a website/blog called www.VitaminDHealth.org. I met Dr. Holick at Boston University many years ago along with Jim Shepherd of KBD. Jim and I were looking into the marketability of a product that Jim’s company now makes. This is a Vitamin D UV Lamp. It is not being sold as a medical device and from what I see on his website  there is no FDA approval (for Vitamin D) on the device(s) that KBD (Sperti) is selling. I am making you aware of this product only, I do not recommend its use. Please check our DISCLAIMER page on this blog.

There are many sites that recommend exposure to UV light to help with Vitamin D production in our bodies. The problem that I see is that there are no guidelines as to which wavelength(s) of UV are most effective, what energy levels are recommended or treatment/dosage times. This leads to anarchy in the field. Some are recommending UVA, some UVB but none that I see give treatment guidelines.

Our firm (www.amjo.net and www.HomePhotoTherapy.com) has avoided offering UV products for Vitamin D production as there are no clear treatment guidlines. I personally recommend that you buy a sports car, drive top down for fun in the sun. This seems to work for me.

Some sites you might want to visit:

• The UV Foundation – www.uvfoundation.org
• The UV Advantage – www.uvadvantage.org
• SUNARC – www.sunarc.org
• Explore Vitamins – www.explorevitamins.co.uk
• Wikipedia – http://en.wikipedia.org/wiki/Vitamin_D 
• Mayo Clinic – www.mayoclinic.com/health/vitamin-d/NS_patient-vitamind

Send me an email or perhaps comment below.

Phototherapy employing sunlight and plants that contain natural psoralens was first used for vitiligo thousands of years ago, and it continues to be a first-line treatment today. Investigators conducted a randomized, double-blind trial to compare two of the most popular forms of phototherapy for vitiligo in 50 patients with nonsegmental vitiligo who received either PUVA or narrowband UVB (NB-UVB) therapy (25 patients in each group).

After treatment (maximum, 144 sessions), subjects in both groups had significant reductions in the extent of vitiligo-involved body surface area. Although between-group differences were not statistically significant, improvement occurred more rapidly and tended to be greater with NB-UVB. After 48 treatments in patients who received that many sessions, the median percentage of improvement in affected body-surface area was slightly more than 20% in the PUVA-treated patients and more than 50% in the narrowband-treated group. The color of the repigmented skin matched excellently the color of uninvolved skin in all NB-UVB recipients but in only 44% of PUVA recipients. Erythema occurred more often with PUVA phototherapy than with NB-UVB therapy (in 96% vs. 68%, respectively). The PUVA recipients received a median of 47 treatments and the narrowband UVB patients, a median of 97; the authors suggest that this is because of the greater efficacy and fewer adverse effects experienced by NB-UVB recipients.

Comment: This study clearly demonstrates that for vitiligo repigmentation, NB-UVB is safer and more effective than PUVA. Other randomized, controlled trials have shown at least some efficacy with targeted phototherapy, topical and systemic steroids, topical calcineurin inhibitors, and calcipotriene combined with PUVA. A number of reports show success with surgical repigmentation procedures, as well. Although we are making progress in treating this vexing disease (especially with calcineurin inhibitors and phototherapy), we still have a long way to go. At best, 75% of patients respond, and in most instances, this response is only partial. A breakthrough in the management of this disease would be greatly welcomed by both patients and doctors. An accompanying editorial provides a nice evidence-based review of existing therapies for vitiligo.

— Craig A. Elmets, MD

Published in Journal Watch Dermatology June 1, 2007

The first report of the use of ‘phototherapy’ in the treatment of skin disorders dates from 1400 BC from India when patients with vitiligo were given certain plant extracts (whose active ingredients included psoralens) and then exposed to the sun. The real interest in the use of ultraviolet (UV) irradiation in the treatment of various skin diseases started in the 19th century when Niels Finsen received the Nobel Prize (1903) for his therapeutic results with UV irradiation in lupus vulgaris, the only dermatologist ever to be awarded one. This marked the start of modern phototherapy. It was used in thermal stations for the treatment of tuberculosis, in the treatment of leg ulcers in wartime, and various other skin diseases. It was a very long journey from the use of plant extracts and sun exposure to treat vitiligo to the use of oral psoralens and total body UVA-irradiation cabins (PUVA) to treat various skin diseases. In a landmark development, in 1974 Parrish et al reported the useful role of high intensity UVA tubes in combination with oral psoralens in the treatment of psoriasis leading to what is now known as PUVA therapy.

The history of UVB phototherapy is not as old as the history of photochemotherapy. Wiskemann introduced irradiation cabin with broad band UVB tubes in 1978 for the treatment of psoriasis and uremic pruritus. However, broad band UVB phototherapy was less efficient for treating psoriasis than PUVA and so never achieved popularity. The breakthrough came after 1988 when narrow-band UVB (NB-UVB) phototherapy was introduced for the treatment of psoriasis by van Weelden et al and Green et al.

Link to entire article << Click Here >>

Excerpted from an article by: Sunil Dogra, Amrinder Jit Kanwar, Department of Dermatology, Venereology and Leprology, Postgraduate Institute of Medical Education & Research, Chandigarh, India

Correspondence Address:
Department of Dermatology, Venereology and Leprology, Postgraduate Institute of Medical Education & Research, Chandigarh – 160102, India
ajkanwar@sify.com

OK, so what’s a dosimeter you ask? UV Phototherapy systems in clinicasl use (in a clinic, hospital or doctor’s office) absolutely require some form of dosimetry. A dosimeter is a device that measures the power of the UV light output from the lamps and determines the treatment time required for that particular treatment session based on the input from the clinician.

In home use, a dosimeter can add significant cost to a phototherapy system and offer no advantage to the home user. In a clinical environment, lamps age, patients might not be using the same phototherapy booth or panel or might go to a different clinic. For these reasons it is important that the treatment dosage, usually measured in Joules or Milli-Joules is known and recorded. Then, if the patient returns to a unit where bulbs have been replaced or perhaps a different booth the last treatment energy in Joules or Milli-Joules is known and can be used to set the dosage for the next treatment.

In the home, the user uses the same machine every day and unless new lamps are installed the power output from the lamps will be essentially the same as the output two days earlier during the prior treatment and the treatment time will usually be the same. Please see my posting on treatment times for the home user <CLICK HERE> 

A Joule is a measurement of ENERGY which is POWER delivered over time. OK so now it’s getting more complicated and for that I apologize. I have created a page called “Joules,

UV Phototherapy is a Safe, Effective, and Economical Vitiligo, Eczema and Psoriasis Treatment

How UV Phototherapy works

UV Phototherapy treatment works by exposing the skin to specific segments of UV light. UV phototherapy treatments are quick and painless. Only the affected areas are exposed. A doctor prescribes the form of ultraviolet light such as UVA, UVB, or narrowband UVB light, as well as length of phototherapy exposure time, number of sessions, and frequency of sessions.

UV Phototherapy is a Safe Treatment

Ultraviolet phototherapy, or UV light therapy, has been studied for over 100 years. The UV phototherapy safety record has been proven in children and for long-term use. Conversely, research into safety of oral, IV or IM medications is limited and a recent Mayo Clinic study suggests a link between new biologic treatments and cancer. Side effects are minimal, though you do need to follow your doctor’s prescription to avoid sunburn. All of our UVA, UVB, and narrowband UVB phototherapy units are equipped with numerous safety features including a controlled prescription timer, child-proof key lock switch and more.

UV Phototherapy is an Effective Treatment for Psoriasis and More

UV Phototherapy is often the most effective psoriasis treatment. While psoriasis treatment is the most common use, phototherapy is also highly effective in treating vitiligo, eczema, hair loss and over 25 other skin conditions. People typically see some improvement immediately and experience clearing with 20 to 25 treatments. Long term remission is experienced for 90 to 95% of cases. Success rates and remission rates are higher for UV phototherapy than for any oral medication or biologic on the market.

UV Phototherapy is an Economical Treatment

Many skin conditions are chronic, genetic diseases. Home phototherapy is often less costly than either long-term medication or regular office visits for UV phototherapy treatments. Insurance companies know this, so most reimburse our phototherapy equipment.

Side benefits of UV phototherapy!

With UV phototherapy, people often report that they enjoy relief from the anxiety caused by living with chronic discomfort. They obtain peace of mind, knowing that their episodes and pain are manageable and that less pain and fewer drugs means better mental health. And, since UV light is sunlight, the therapy itself often has a calming effect.

Typical Rectangular Woods Lamp Made by Waldmann

Perhaps a little off topic. The Black Light or the Woods Light is a low energy ultraviolet emitter  usually at 365 nm. All kinds of DNA based materials fluoresce when illuminated by a UV source. In fact one of the primary uses of a Woods Light is in the detection and determination of Vitiligo. Vitiligo is a skin condition where the skin becomes depigmented and turns white. The resulting white spots glow brightly in the presence of the light from a Woods Lamp.

Vitiligo on Hands

To see a selection of images where the skin fluoresces. Click here http://msp.rmit.edu.au/Article_01/14_gallery.html. Vitiligo is an equal opportunity  disease affecting 1% to 2% of the world’s population. We tend to notice it more in dark skinned people because of the greater contrast between the light and dark skin tones. Materials that fluoresce are materials that are affected by the UV light and they themselves emit light. If you’ve ever entered a bar with black lights over the dance floor, you’ve seen how some fabrics and other items glow in the presence of UVA / Black Light.

 Typical Applications for Woods Lamps or Woods Light are very diverse. In the medical field there are several applications. We also find them used in criminology (forensics), mineralogy and gemology to detect fluorescence in many minerals and gems.

We will attempt here to list some of the major applications of our woods lights or woods lamps.

Medical Uses

Several skin diseases/challenges such as vitiligo, acne and a host of others cause the skin (or the fluids on the skin) to fluoresce.

• Vitiligo
• Bacterial Infections
• Acne
• Porphyria
• Erythasma 
• Alopecia
• Tinea Versicolor
• Fungus & Fungal Infections
• Head Lice and their nits, fluoresce under black light.
• Ringworm
• Scabies
• Child abuse / bruising can often be discerned with a woods light.

Why is it useful to be examined with the Wood’s lamp? Normally your skin will not fluoresce, or shine, under the ultraviolet light. This test reveal different colors according to the type of skin disease, which may include:

• Golden Yellow (Tinea Versicolor)
• Pale Green (Trichophyton Schoenleini)
• Bright Yellowgreen (Microsporum Audouini or M. Canis)
• Aquagreen To Blue (Pseudomonas Aeruginosa)
• Pink To Pinkorange (Porphyria Cutanea Tarda)
• Ash-Leaf-Shaped Spot (Tuberous Sclerosis)
• Bluewhite (Leprosy)
• Pale White (Hypopigmentation)
• Purplebrown (Hyperpigmentation)
• Bright White, Or Bluewhite (Depigmentation, Vitiligo)
• Bright White (Albinism)

Ophthalmology

When used with sodium fluorescein or other fluorescing dyes, there are several applications for the world of the eye doctor.

• Foreign Particles in the Eye (glass and other hard to see particles)
• Eye Injury
• Scratches of the cornea
• Blocked Tear Ducts

Veterinary Applications

• Ringworm
• Urine Stains
• Eye challenges
• Lice and Nits
• Microsporum Canis
• Fungal Infections

Miscellaneous Uses

• Pets, small and large leave urine and feces in places that you would least expect. Feces, urine and other biological contaminants/materials can be detected easily with UVA Woods Lights.
• Hard water detection. Many “Culligan Men”, water softener sales people carry a UVA black light as many hardened mineral deposits on taps, sinks etc fluoresce with black light.
• Re-admittance inks. Fluorescent Ink detection. Some invisible inks such as those uses at some night clubs and amusement parks for re-entry stamps can ne seen under UV (Black Light)
• Rodent urine and traces fluoresce under black light. One can monitor/detect some forms of rodent activity with a simple woods lamp.
• Fraud detection. Some of our money has fluorescent dyes within.

UVA light is used in conjuntion with a Psoralen for phototherapy. The term then becomes PUVA (“P” UVA). This technology was very common but over the last ten years or so there has been a migration towards the use of UVB Narrowband which is generally considered to be the equal of PUVA but without the side effects. See http://www.uvbnarrowband.com/?p=41 for some info on the undesirable effects of PUVA.

UVA light is the main component of the light from a tanning bed. UVA without the use of a Psoralen to sensitize the skin does little for the treatment of most skin problems. UVA penetrates deeply and can cause premature aging of the skin while passing through the upper layers of the skin where the skin challenges such as Psoriasis, Vitiligo and Eczema reside.

UVA (PUVA) is becoming less and less popular as a treatment modality for most skin challenges.

One interesting application of UVA is its use at low energy levels as a “Woods Light” for skin inspection and forensic work. Many chemicals and DNA based materials fluoresce in the presence of UV light. The Wood’s Light was invented by Dr. Robert Woods early in the twentieth century.