PAM Light & Laser Therapy 3 — Questions and Answers
Question 1: Infrared lamp therapy is primarily used to produce which physiological effect in superficial tissues?
- Photochemical reactions in DNA
- Superficial tissue heating to a depth of 1–2 cm (Correct answer)
- Destruction of microorganisms via UV radiation
- Deep muscle relaxation via direct nerve stimulation
Correct answer: Superficial tissue heating to a depth of 1–2 cm
Infrared lamps produce superficial thermal effects, raising tissue temperature within the top 1–2 cm primarily through radiation heat transfer.
Question 2: The minimum safe distance typically recommended between a luminous infrared lamp and a patient's skin is:
- 5–10 cm
- 45–60 cm (Correct answer)
- 90–120 cm
- 150–200 cm
Correct answer: 45–60 cm
A distance of 45–60 cm is standard for luminous IR lamps to deliver comfortable warmth without risk of thermal burns.
Question 3: Which of the following conditions would MOST benefit from ultraviolet (UV) therapy?
- Acute ankle sprain
- Psoriasis plaques (Correct answer)
- Carpal tunnel syndrome
- Trigger point pain in the trapezius
Correct answer: Psoriasis plaques
UV-B therapy is a well-established treatment for psoriasis, inhibiting keratinocyte proliferation and modulating immune responses in the skin.
Question 4: The minimal erythemal dose (MED) in UV therapy is defined as:
- The dose that causes permanent skin darkening
- The smallest UV dose that produces just-perceptible redness 8–24 hours after exposure (Correct answer)
- The maximum safe dose for a treatment session
- The dose required to kill surface bacteria
Correct answer: The smallest UV dose that produces just-perceptible redness 8–24 hours after exposure
MED is the threshold dose producing a barely visible erythema 8–24 hours post-exposure, used as the baseline for calculating therapeutic UV dosing.
Question 5: A patient is receiving UV therapy and develops a first-degree UV burn (Grade 1 erythema). The therapist should:
- Continue treatment at the same dose
- Withhold treatment until erythema resolves, then restart at 75% of the previous dose (Correct answer)
- Increase the next dose by 25% to maintain therapeutic effect
- Switch immediately to infrared therapy
Correct answer: Withhold treatment until erythema resolves, then restart at 75% of the previous dose
Unplanned erythema (Grade 1 burn) requires resting until the reaction clears, then resuming at a reduced dose to prevent further skin damage.
Question 6: Which UV wavelength band is primarily responsible for bactericidal effects and is used for wound disinfection?
- UVA (320–400 nm)
- UVB (280–320 nm)
- UVC (200–280 nm) (Correct answer)
- Near-UV (400–420 nm)
Correct answer: UVC (200–280 nm)
UVC (200–280 nm) has the strongest germicidal effect by disrupting bacterial DNA, and is used clinically to reduce wound bioburden.
Question 7: During laser therapy, protective eyewear must be worn because laser light poses the greatest risk to which ocular structure?
- Cornea only
- Iris and pupil
- Retina (Correct answer)
- Lens and vitreous humor
Correct answer: Retina
The retina is most at risk because the eye's lens focuses laser light to a small spot on it, potentially causing irreversible thermal or photochemical damage.
PAM Light & Laser Therapy 3
Infrared lamp therapy is primarily used to produce which physiological effect in superficial tissues?