CLT Cheat Sheet 2026

The 30 highest-yield CLT facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What is a key consideration in Client Assessment & Treatment Planning? → Apply client assessment & treatment planning best practices
2. What term describes the scattering of light in multiple directions as it passes through tissue? → Diffuse reflectance
3. What is a key consideration in Safety Protocols & Contraindications? → Apply safety protocols & contraindications best practices
4. Which finding best indicates that a wound has successfully entered the remodeling phase? → Wound contraction, decreased depth, and early scar tissue formation
5. Which practice is considered a boundary violation in a CLT-client professional relationship? → Accepting a substantial personal gift from a client in exchange for discounted sessions
6. What phenomenon occurs when light passes from air into tissue and changes direction? → Refraction
7. What is a key consideration in Human Anatomy & Light Interaction? → Apply human anatomy & light interaction best practices
8. Which safety device is mandatory for all personnel present during Class III and IV laser treatments? → Wavelength-specific protective eyewear (laser safety glasses/goggles)
9. What is a chromophore in photobiology? → A molecule that absorbs specific wavelengths of light
10. Which molecule absorbs green light (around 540 nm) and is relevant to vascular light therapy treatments? → Oxyhemoglobin
11. What is the primary purpose of red light therapy? → To promote skin healing and reduce inflammation
12. What classification system is used in the US to categorize the safety level of laser and light devices? → FDA Class I through Class IV laser classification system
13. What is a key consideration in Safety Protocols & Contraindications? → Apply safety protocols & contraindications best practices
14. Which wavelength range penetrates the deepest into human tissue? → Near-infrared (700–1100 nm)
15. What is the primary mechanism by which 630–660 nm red light promotes fibroblast activity in wound healing? → Photon absorption by cytochrome c oxidase increasing ATP and cellular metabolism
16. What is the Fitzpatrick Skin Phototype Scale used to determine? → A client's skin response to UV exposure, guiding safe light therapy dosing
17. What is a key consideration in Safety Protocols & Contraindications? → Apply safety protocols & contraindications best practices
18. What is a key consideration in Safety Protocols & Contraindications? → Apply safety protocols & contraindications best practices
19. What wavelength range is most commonly used in photobiomodulation for promoting wound healing? → 600–1100 nm (red to near-infrared)
20. The Arndt-Schulz law as applied to photobiomodulation states that: → Low doses stimulate, moderate doses inhibit, and very high doses destroy
21. What is irradiance in the context of light therapy? → Power per unit area (mW/cm²)
22. What is a key consideration in Safety Protocols & Contraindications? → Apply safety protocols & contraindications best practices
23. What is a key consideration in Human Anatomy & Light Interaction? → Apply human anatomy & light interaction best practices
24. What is a key consideration in Client Assessment & Treatment Planning? → Apply client assessment & treatment planning best practices
25. What is a key consideration in Human Anatomy & Light Interaction? → Apply human anatomy & light interaction best practices
26. What is the purpose of a cold gel or contact cooling system used with some light therapy devices? → To protect the epidermis from thermal damage while allowing deeper chromophore targeting
27. Which light therapy technique helps regulate circadian rhythm? → Bright light therapy
28. Seasonal Affective Disorder (SAD) is primarily treated with which type of light therapy? → Bright white light (10,000 lux) exposure in the morning
29. Which of the following is an example of a subjective measurement tool used to track light therapy outcomes? → A validated pain or symptom rating scale completed by the client (e.g., VAS, NRS)
30. Which type of scarring is raised above the normal skin surface and extends beyond the original wound boundary? → Keloid scar