Table 1 Effect of low-level laser therapy (LLLT) on human sperm parameters
From: Applications of laser technology in the manipulation of human spermatozoa
Study | Source of sperm | Type | Device | Type of light and wavelength | Intensity/duration of exposure | Main findings and results | References |
|---|---|---|---|---|---|---|---|
Sato et al. (1984) | Normal sperm | Fresh | Krypton Laser | Red light (647Â nm) | 0.5, 1.0, 2.0, 4.0, 8.0, and 32Â J/cm2/80 and 160Â s | Total sperm motility increased after Laser irradiation at 4Â J/cm2, 8Â J/cm2, and 32Â J/cm2 respectively compared with control. | [12] |
Lenzi et al. (1989) | Normal sperm | Fresh | LM infrared laser | Infrared laser | 5–30 mW/120 s | Laser irradiation had a positive effect on sperm motility. | [22] |
Singer et al. (1991) | Normal and abnormal sperm | Fresh | BioBeam instrument | Infrared laser (940Â nm) | Maximal intensity 20 mW/cm2/4 min | Light exposure significantly increased the percentages of motile, viable, and morphologically normal sperm. | [31] |
Firestone et al. (2012) | Normospermia, oligospermia, and asthenospermia | Fresh | Theralaser TLC-1000 | Laser light (905Â nm) | 50 mW/cm2/30 s | Low-level laser light had a positive short-term effect on the motility of sperm and did not cause any increase in DNA damage measured at 2Â h. | [26] |
Salman Yazdi et al. (2014) | Asthenzoospermia | Fresh | GaAlAs laser | GaAlAs laser (830Â nm) | 4, 6, and 10Â J/cm2/0, 30, 45, and 60Â min | Irradiating human sperms with low-level 830-nm diode lasers can improve their progressive motility depending on both laser density and postexposure time. | [25] |
Preece et al. (2017) | Healthy men | Frozen-thawed | Monochromatic coherent laser (Intense 7404) | Red laser light (633Â nm) | 5.66 mW/cm2/35 min; 31mW/cm2/30 min | Red light improved sperm motility and did not induce oxidative DNA damage. | [19] |
Gabel et al. (2018) | Human | Fresh and frozen-thawed | GaAlAs | GaAlAs single laser (810Â nm) and an LED cluster (660 and 850Â nm) | GaAlAs single laser: 200 mW/10, 20, and 40Â s for frozen sperm, and 15,20, and 300Â s for fresh sperm LED cluster: total power 2Â W/25, 50, and 75Â s for frozen sperm, and 50,100, 200, and 400Â s for fresh sperm | The sperm motility index and total functional sperm count increased up to fourfold compared to controls. The motility modification was dependent upon beam irradiance and irradiation time as well as the condition of the sample. | [20] |
Highland et al. (2018) | Normal sperm | Fresh | NA | NIR radiation (750–1100 nm) | 87 lux/15 min | NIR radiation resulted in a loss of viability and membrane function, increased free radical formation, and induced sperm apoptosis. | [23] |
Safian et al. (2020) | Normal sperm | Fresh | Diode laser probes (NILTVIR202 Noura Instruments) | NIR light: 810Â nm | 0.6Â J/cm2/NA | PBM treatment before cryopreservation significantly increased the percentages of viable sperm, sperm with high membrane potential, and high mitochondrial activity. | [21] |
Safian et al. (2021) | Normal sperm | Fresh | Diode laser (NILTVIR202 Noura Instruments) | Red light (630 nm), NIR (810 nm), or red + NIR (630 + 810 nm) | 0.6, 1.2, and 2.4 J/cm2/15, 30, and 60 min | The NIR laser at 0.6 J/cm2 energy density significantly increased sperm motility and viability and decreased the DNA fragmentation index compared with the red and red + NIR protocols. | [27] |
Espey et al. (2022) | Asthenozoospermia and normozoospermia | Fresh | Pulsed laser-probe (Reimers & Jansen) | Pulsed laser-probe (655 nm) | 4, 6, and 10 J/cm2/0, 30, 60, 90, and 120 min | Exposure to laser energy doses of 4 and 6 J/cm² improved sperm motility and velocity in asthenozoospermic patients. | [24] |
Safian et al. 2022 | Normal sperm | Fresh | Diode laser (NILTVIR202 Noura Instruments | NIR light: 810Â nm | 0.6Â J/cm2/NA | PBM therapy before cryopreservation significantly improved the quality of post-thawed human sperm. | [28] |