The FDA has approved numerous laser treatments for a “temporary increase in clear nail in patients with onychomycosis,” but lasers have not been established as a cure, and there is a scarcity of peer-reviewed literature addressing the subject [15]. Among these FDA-approved lasers for onychomycosis treatment are Fractional CO2 laser and Q-switched laser [5].

Our study aimed to compare the clinical efficacy and safety of fractional CO2 laser combined with topical tioconazole nail solution versus Q-switched 1064 Nd: YAG laser in the treatment of fingernail onychomycosis. To the best of our knowledge, this study is the first to make such a comparison in the treatment of onychomycosis.

In the current study, it was observed that distal and lateral subungual onychomycosis (DLSO) (59.6% of included nails) was the most predominant clinical type of onychomycosis, followed by TDO (40.4%). This aligns with other studies, which showed DLSO (62.5%) as the most prevalent, followed by (20.8%) with PSO and (12.5%) with TDO [16, 17].

Regarding therapeutic efficacy, a significant reduction in the mean OSI score was noted in nails treated with fractional CO2 laser, while there was no significant reduction in the mean OSI score in nails treated with Q-switched Nd: YAG laser. Overall, 37.5% of nails showed good responses in the fractional CO2 group, compared to only 13% in the Q-switched Nd: YAG group.

Our results align with studies reported in the literature. El-Tatawy and colleagues (2019) investigated the role of fractional CO2 laser and topical tioconazole 28% nail lacquer in the treatment of fingernail onychomycosis, finding significantly better improvement in both laser and combined groups compared to the topical group [18]. Similarly, Abd El-Aal and colleagues (2019) evaluated the efficacy of fractional carbon dioxide laser-assisted delivery of topical tazarotene versus topical tioconazole, showing comparable clinical responses in both groups [19].

In addition, Bhatta and colleagues (2016) studied the efficacy of fractional CO2 laser combined with a topical terbinafine cream, with 73.32% of patients having fully or more than 60% normal-appearing nails after 3 months from the last treatment [4].

In contrast to our study, Elmorsy and colleagues (2020) investigated the efficacy of Long Pulsed Nd: YAG (1,064 nm) Laser versus Q-Switched Nd: YAG (1,064 nm) Laser for the treatment of onychomycosis, with both groups showing statistically significant improvement in proximal nail plate measurements. However, clinical success was higher in group II at both the end of treatment and 6 months follow-up [20].

Galvan Garcia (2014) evaluated the efficacy of the 1064-nm Q-switched Nd: YAG laser in the treatment of onychomycosis, reporting a 93% clinical response rate within 3 months of the initial laser treatment and a 100% clinical response rate at 6 months [9].

The higher clinical efficacy of Q-switched Nd: YAG laser in other studies compared to our study could be explained by longer follow-up periods. In our study, the poorer results of Q-switched Nd-YAG laser compared to fractional CO2 laser may be due to a significantly higher baseline mean OSI for included nails in the Q-switched Nd: YAG group, and severe onychomycosis was associated with poor results in both treatment groups.

However, fractional CO2 laser was slightly better in improving severe onychomycosis. Although this was statistically insignificant, 3/11 nails improved versus 0/16 in the Q-switched Nd: YAG laser group. Although both treatment groups showed a statistically significant improvement in mean DLQI score, there was no statistically significant difference between them.

A statistically significant incidence of mycological cure in KOH examination was detected in both the fractional CO2 group and the Q-switched Nd: YAG group, with no significant difference between them. This is consistent with studies by Abd El-Aal and colleagues (2019) and El-Tatawy and colleagues (2019), where mycological cure rates were reported [18, 19].

However, the overall good responses associated with negative KOH microscopy after treatment were lower in the fractional CO2 group (33.3%) compared to the Q-switched Nd: YAG group (66.6%). Poor responses associated with negative KOH microscopy after treatment may be due to the possibility of false-negative results of KOH, with reported sensitivity ranging from 48 to 60% [21].

Regarding the disappearance of different dermoscopic patterns in the treated nails, both types of laser had comparable effects. In conclusion, Fractional CO2 laser combined with topical tioconazole is more efficient in the treatment of onychomycosis than Q-Switched Nd: YAG 1064 nm laser group in terms of clinical improvement, but both have a comparable effect on mycological cure. Both treatments are safe and are better used as adjuvant treatments rather than alone to ensure mycological cure in onychomycosis.

Limitations of the current study include the short follow-up time of one month, preventing a conclusion about how long the laser effect would last or further improve the condition.