Phototherapy

While the uses of phototherapy clinically are many, three main domains of use exist. The techniques, equipment, procedures and overall target of treatment vary depending upon the disorder being treated. Following are some of the uses of phototherapy:

• Phototherapy in dermatology: Phototherapy has a major role in the treatment of many skin conditions, either as monotherapy (without the use of any other treatment modality) or as an adjunct in addition to other treatments. Ultraviolet light energy is most commonly used in the treatment of skin conditions. The underlying principle dictating ultraviolet light use for dermatological conditions is the stimulation of vitamin D synthesis in the skin. Skin conditions that have established the role of phototherapy in their treatment include, but are not limited to:
  • Psoriasis: Psoriasis is an autoimmune disease (autoantibodies formed by the body’s immune system attack its own cells) that affects the skin and joints. It results in new skin production being sped up ten times. The trunk, upper and lower limbs, head, scalp, face, skin creases (like that of the armpits and groin) can show skin involvement. The typical psoriatic rash consists of itchy red raised oval patches with silvery or white flaking scales. Elbows and knees usually have typical rashes. Fingernail changes and arthritis (joint inflammation) can occur with it, as well as other systemic symptoms affecting the individual’s overall health and immunity.
  • Vitiligo: Vitiligo is a disease in which the pigment cells of the skin (melanocytes) may die and depigmentation appears as white blotches. Although it affects individuals of all ethnicities and races equally, it is more noticeable in people with darker complexions. Treatment can be done, using agents applied directly to the skin and phototherapy, to improve the cosmetic outlook but the disease itself is incurable.
  • Atopic dermatitis: Atopic dermatitis, also known as eczema, is a condition characterised by the appearance and disappearance of red itchy rashes, generally in the skin flexures (like elbow, wrist or knee creases). It is common in children but can persist in adulthood. It generally occurs in individuals who have a history of allergies (including bronchial asthma) or have close relatives (like siblings or parents) who suffer from eczema or allergies. Although the first-line treatment of atopic dermatitis is the use of emollients (oil-based agents that restore skin moisture) and topical steroids (mild to very potent depending on the severity of the disease) that are rubbed into the skin (emollient is applied first and steroid thirty minutes later), phototherapy can be used as an add on to improve the outcome of treatment.
  • Acne vulgaris: Acne vulgaris, or simply acne, is a bacterial infection of the blocked sweat glands (and their accompanying hair follicle units) that causes pus-filled blisters (pustules) or pimples to form. Treatment of acne involves the use of agents applied directly onto the skin and oral treatment but can also include phototherapy for enhanced results in appropriate cases.
  • Lichen planus: Another autoimmune disease affecting the skin and mucous membranes (especially oral mucosa) that is characterised by the formation of itchy purple raised polygonal lesions, commonly at the wrist. Phototherapy plays a role as add-on therapy in the treatment of lichen planus.
• Phototherapy in psychiatry: By mimicking natural sunlight, some psychiatric conditions affecting the body’s internal clock can be treated with phototherapy. Some other mood disorders, unrelated to seasonal changes, can also improve with phototherapy.
  • Seasonal affective disorder (SAD): Mood disorders that arise in a patient at a particular time each year (season) in a geographical location are called seasonal affective disorders (SAD). Depressive symptoms commonly arise in individuals living in areas that receive very little sunlight and experience shorter days in winter. Treatment is mainly with phototherapy. Medicine and psychotherapy (talk therapy) can be included.
  • Non-seasonal depression: Bright light phototherapy offers therapeutic improvement in mood disorders unrelated to seasonal changes (like major depressive disorder and bipolar disorder) when used in adjunct with medical therapy and psychotherapy.
  • Chronic circadian rhythm sleep disorders: Sleep disorders inhibit individuals from going to sleep and waking up at the stipulated time and cause them to expel daytime sleepiness. Their treatment involves behavioural changes and phototherapy. Medicines like melatonin, modafinil and caffeine can help.
• Phototherapy for jaundice in newborn babies (or neonatal hyperbilirubinemia): Newborn babies have immature livers that are not fully able to metabolise bilirubin (the blood red pigment breakdown product) and its accumulation can lead to the yellow appearance of skin and eyes. While most newborn jaundice cases are mild and resolve on their own, more severe forms need medical attention, which includes phototherapy. Very severe cases can necessitate blood exchange transfusion.
• Phototherapy in cancer: Laser therapies like photobiomodulation (PBM) and photodynamic therapy (PDT) utilise laser light energy to treat cancerous tumours.
• Phototherapy for retinal disease: Some experimental studies have found that the use of phototherapy in diabetic retinopathy and macular edema hold promise as a treatment option. Further research is being carried out.

Three major, and commonly employed, domains of phototherapy use are described below. Other uses of phototherapy can differ depending on the condition being treated.

Certain factors can warrant further assessment before proceeding with phototherapy and may also make its use inappropriate. Relative contraindications to phototherapy include:

• Childhood
• Pregnancy and breastfeeding (PUVA is contraindicated)
• Immobility or inability to stand unassisted for 10 minutes or longer
• Very fair skin (especially with  PUVA)
• Past excessive exposure to natural sunlight or phototherapy
• Immunosuppressive medication
• Photosensitising creams or medications
• Past skin cancer, especially melanoma
• Any type of lupus (systemic lupus erythematosus, discoid lupus, etc): photosensitivity associated with lupus can cause complications with phototherapy.
• Preexisting skin conditions like xeroderma pigmentosum (which makes people very sensitive to sunlight)

Some adverse effects are known to occur with the use of phototherapy and can warrant careful risk assessment, on a case by case basis, for the best possible outcome for the patient. These side effects vary with the type of phototherapy used and can include the ones mentioned below.

• Complications with dermatological phototherapy:
  • Redness of skin 
  • Soreness of skin
  • Blistering of skin
  • Change in the pigment of skin (more noticeable in individuals with darker skin tones)
  • Burning
  • Itching
  • Hyperpigmentation
  • Swelling
  • Photo-ageing: Wrinkling, freckling, xerosis, telangiectasia, elastosis (increased skin elasticity) and atrophy (increased fragility of skin)
  • Skin cancer: The risk of both melanoma and non-melanoma skin cancers increases with the use of phototherapy. The risk is more significant in individuals with a history of skin cancer (personally or in the family), other skin conditions and a history of exposure to radiation (X-rays). Psoralen ultraviolet A (PUVA) phototherapy poses the highest risk (proportional to the number of sessions; significant increase after 150 sessions). Genital skin cancer is a risk with ultraviolet B phototherapy and thus the shielding of gonads is warranted.
• Complications of newborn phototherapy: Phototherapy in newborn babies is safe and effective in almost all cases. Some temporary side effects can arise:
  • Rashes
  • Loose stools
  • Overheating
  • Dehydration (Read more: Dehydration in children)
  • Discolouration of stool and/or urine
  • Dark greyish-brown discoloration of the skin that disappears on its own in a few weeks