The effectiveness of lasers in the treatment of onychomycosis: a systematic review Part 2 of 3.
Initial evaluation demonstrated a variety in study procedures which precluded detailed statistical comparisons and so a structured review of the papers was undertaken to examine and compare methods and results. In total, 13 papers were initially deemed eligible, however one paper  was an extension of an earlier published paper already included in the review  so was excluded.
All of the 12 remaining papers were published in the last four years [25-36]. Reflecting the novelty of this technology, four studies stated they were "preliminary" or pilot studies [26-28,31]. Two papers adopted a randomised controlled trial methodology [25,29], three were comparative designs [27,35,36] whilst the remainder were case series [26,28,30-34].
The majority of studies (10 papers) investigated the 1064nm neodymium: yittrium-aluminum-garnet laser system (Nd:YAG) (long and short pulse types) either as a sole intervention [26-29,31,33,34,36], as a Q switched 1064 nm/532nm wavelengths system , or as a comparison against a 1319 nm and broadband wavelength device . One study employed an 870/930 nm dual band system  and another investigated the use of an ablative carbon dioxide laser as a means to fractionate nails to enhance the penetration of topical anti-fungal agents .
Three papers stated that fingernails had been included in the study [28,33,36] but none exclusively, so were included. A tabulated summary of all included studies is given in Table 1 along with an assessment of the level of evidence and validity measures in Table 2. In a randomized controlled trial by Landsman and colleagues , 36 patients with proven onychomycosis were randomly allocated to either a laser treatment using a continuous wave Noveon[TM] 870 nm/930 nm laser or control sham device. Following a detailed protocol, all patients were treated at day 1, 14, 42 and day 60. Blinded assessors reviewed photographic evidence at various stages to assess and record any changes. At 6 months, 34 patients (37 toes: 26 treated and 11 controls) were eligible for analysis. Visually, only 2 treated nails had completely or markedly improved (versus 2 controls) whilst slight to moderate improvement was seen in 18 treated nails versus 3 control nails and 6 treated nails were unchanged along with 6 control nails. The study was declared as being funded exclusively by a laser manufacturer and employees of the company were listed as co-authors of the paper. In another randomized controlled trial, Hollmig et al.  enrolled 27 patients with culture or PAS stain confirmed onychomycosis to receive either 2 treatments with a 1064 nm Nd:YAG laser (two weeks apart) or no treatment. At three months all patients affected nails were reassessed by culture and measured nail clearance with an additional measurement for the treated group at month 12. The results showed that at 3 months, 33% of the laser treated group achieved a negative culture versus 20% in the control group and had more proximal nail clearance at this time, although there was no statistically significant difference between the two groups. At month 12, there was no difference in measured nail clearance between the treated and control group. The authors suggested that the laser may only have a temporary effect in onychomycosis. Hochman  undertook a study of 8 patients with culture or PAS stain confirmed onychomycosis and treated them using a LightPod NeoTM 1064 nm short pulsed Nd:YAG laser (Nd:YAG laser). After 2-3 treatments, three weeks apart, they were reassessed at an unspecified follow-up time of at least 4 months. The author reported a 7 out of 8 patients showing visual improvement (although this was not quantified) and negative fungal cultures. However, in this study, no description was given about the level of nail involvement at the beginning of the study to ascertain the extent of the disease. In addition, patients were encouraged to use daily antifungal agents during treatment applied to the nail. Small numbers were used in this study and the follow up time was not formalized ranging from 16 to over 24 weeks.
Published in 2012, Kimura et al.  undertook a study of 13 subjects (37 toe nails) and investigated the effective ness of the Cutera[TM] Nd:YAG short pulse laser in the treatment of patients with dystrophic nails, microscopically confirmed as onychomycosis. Nails were treated two or three times 4-8 weeks apart. The main outcomes assessed were evidence of clear nail growth (using a nail turbidity score) and a negative fungal clipping. The majority of patients presented with distal lateral subungual onychomycosis (n = 9). At the end of the study (week 16) 19 nails (51%) showed complete clearance (clear nail and negative microscopy) with 30 nails (81%) showing from moderate to complete improvement. The authors declared that the equipment for the study had been loaned from the manufacturers but did not state if the results were independent of the company.
In a more recent study by Moon et al.  43 toenails and 12 finger nails with culture and PAS stain confirmed onychomycosis underwent 5 treatments using a Nd:YAG 1064 nm laser system at four week intervals. At 24 weeks from the start of the study nails were assessed for surface clearance and negative cultures. One month after the final treatment 30 of the 43 nails had negative microscopy. Four nails achieved a complete cure (negative microscopy and complete visual clearance in the nail plate). Eight patients were reported to have achieved >80% nail clearance and 31 nails (50-80% clearance of nail surface area).
Using the Pinpointe[TM] Laser System (1064 nm Nd: YAG) with a long pulse duration, Zhang and colleagues  randomly assigned into two treatment groups, 33 microscopically and fungal culture positive patients (154 nails) with onychomycosis to either 8 treatments at one week intervals (group 1) or 4 treatments at one week intervals (group 2). Patients were followed up for 24 weeks. There was no significant difference in the mycological cure rates which were 51% (group 1) and 53% (group 2) at 24 weeks. Interestingly, they reported recurrence on the disease in 10 nails (5 patients) within a 2-4 month period after the study, suggesting that the laser had only temporarily inhibited growth and not destroyed the fungus outright.
Waibel et al.  undertook a study using three types of laser light (1064 nm, 1319 nm and broadband filtered flash light) randomly assigning 21 patients to one of the modalities. All patients had PAS confirmed disease and had positive microscopy cultures. Each nail was treated with 10 minutes of laser light and received four, weekly treatments and were assessed at 1, 3 and 6 months. Tissue temperature was also recorded in this study to suggest what effect the laser was having on the treated area. The authors reported improvement in the nail appearance with "clearing" and a high satisfaction rate, with only mild discomfort reported by patients. Although these findings were not quantified, they reported 100% negative cultures for the 1064 nm laser system and Broadband light with one failure for the 1319 nm system. The sample sizes for this study were small with 7 subjects in each arm. A measured temperature of 46 degrees centigrade was achieved for all treatments. Based on the results the authors concluded that this was a lethal temperature which would achieve the desired outcome.
In a larger study Kalokasidis et al.  treated 131 patients with microbiologically confirmed onychomycosis using a Q-Clear[TM] Q-Switched Nd:YAG 1064 nm/532 nm laser following nail reduction with a drill. Patients underwent two treatments, 30 days apart, using both wavelengths each time and then were reviewed at two months. The results demonstrated an impressively high cure rate, assessed by microscopy and culture, of 95.4% in the study group which is much higher than other studies have reported. The data suggested that distal subungual onychomycosis and superficial white onychomycosis are very amenable to this modality whilst lesser results were observed in patients with severely dystrophic nails. As the authors state the follow up time for assessment in this study was very short as effective nail growth can take up to 12-18 months to fully reveal the nail postoperatively. Although the nail severity index was used initially to assess nail involvement, subsequent score post-intervention were not fully reported.
In a Japanese paper, Noguchi et al.  treated the hallux nails of 12 mycological positive patients with a GentleYAG[TM] 1064 Nd:YAG laser. Nails with severe disease were excluded (>75% surface area affected or >3 mm plate thickness) so the treated group only presented with distal lateral subungual onychomycosis type. All patients underwent the minimum of 3 treatments at 4--week intervals with nail turbidity (clearance) assessed at 3 and 6 months. Mycological cure rates were not assessed in this study, only visible improvement measured through changes in affected nail surface area. Only three patients showed a significant improvement (25%) with two showing improvement (16.7%) and six patients (50%) showing no improvement or worsening. The authors concluded from their results that this procedure was no better than topical nail lacquer therapy based on the cure rates achieved.
Carney et al.  as part of a range of experiments undertook a study of 10 patients (18 nails) with onychomycosis. In the clinical part of their study, they selected 10 patients with mycologically proven onychomycosis and undertook a treatment using a single 1064 nm Nd: YAG system.
This study included rigorous assessment of the nails before and after using the OSI measure as well as the mycological evidence to assess outcomes with a 24 week programme. They could not show significant improvements in mycological or clinical cure rates using this laser system and regime.
Hees et al.  reported a ten patient pilot study also employing a comparative design of the two types of 1064 Nd:YAG systems (short pulse versus long pulse). Patients included had all grades of onychomycosis caused by T rubrum with mycological confirmation in both halluces and underwent a left hallux/right hallux comparison of the two laser systems with a two treatment regime spaced four weeks apart to both nails. Nail changes were independently assessed by two observers using standardised photography and the OSI  with a nine month follow up. Despite mycological clearance rates of around 65% in this small sample, the OSI grading changed very little for participants--improving slightly within the first six months and then reversing slightly at the end of the nine month study. In conclusion, although 65% had mycologically been cured, clinically only 4 cases had shown visible improvement.
Only one study evaluated the carbon dioxide ablative laser (CO2) in the treatment of onychomycosis . The function of laser therapy in this study was to render the nail more permeable to facilitate penetration of concurrent topical amorolfine to affected nails which was then evaluated. After three treatments at 4 week intervals, 24 patients with confirmed onychomycosis were assessed at six months for negative cultures and improvements in clear nail growth. At this time, 50% of patients had negative culture and had 100% nail clearance whilst only 2 patients (8%) showed no response. As the authors point out, mild forms of onychomycosis such as superficial white onychomycosis responded best whilst no improvement was seen in the totally dystrophic cases.
A discussion of these results will follow in the next issue of Podiatry Review
References and End Notes (for part 2)
AOTA: American Occupational Therapy Association; DLSO: Distal lateral subungual onychomycosis; FDA: Food and Drug Administration; Nd: YAG: Neodymium:Yttrium Aluminum Garnet (laser); OSI: Onychomycosis severity index; PAS: Periodic Acid-Schiff stain; PCR: Polymerase Chain Reaction; PWSO: Proximal white subungual onychomycosis; RCT: Randomised Controlled Trial; SWO: Superficial white onychomycosis; TDO: Total dystrophic onychomycosis.
The author declares he has no competing interests.
IB was responsible for the drafting of the paper and conducting the review. All authors read and approved the final manuscript.
Received: 15 April 2014 Accepted: 17 July 2014
Published: 27 July 2014
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