Use of fractional CO2 laser improves distal and lateral subungual onychomycosis: IDOJ

It is a very good option in patients with comorbidities or those on other medications. Existing literature regarding the type of infection treated, optimum treatment protocols, cure rates, and long‑term follow‑up is limited. Recently an article demonstrating efficacy of combination of topical therapy and fractional CO2 laser in onychomycosis was published in the Indian Dermatology Online Journal.

Many factors can influence treatment outcomes like nail‑plate thickness, extent/type of OM, number of sittings, and concomitant therapy. Fractional CO2 laser offers a simple means of creating fenestrations in nail. Nail fenestration improves topical drug delivery by three‑ to fourfold over 42 days. Thus it is logical to use fractional CO2 laser as pre-treatment for OM in combination with topical therapy.

This study was conducted for clinical evaluation of the efficacy of 30 W fractional CO2 laser in toenails with distal and lateral subungual onychomycosis (DLSO). Patients included either had a lack of response or contraindication to oral antifungals. Diagnosis of OM was confirmed mycologically with direct microscopy (potassium hydroxide [KOH] mount) and fungal culture.

Two patients with seven involved toenails with DLSO were recruited. One of them (19/M) had not responded to systemic therapy over the past 1 year with terbinafine and itraconazole (both administered for 12 weeks each with an intervening period of 3 months). The other (23/F) had developed a fourfold increase in transaminase levels with terbinafine, which normalized over 2 months after stopping the drug so was reluctant to take oral therapy thereafter. All the nails were KOH positive with Trichophyton rubrum growth in culture.

Treatment protocol of three incremental laser sessions (microbeam diameter of 0.6 mm, density 166/mm²) at 4 weekly intervals with daily application of ciclopirox nail lacquer (8%) (CNL) was explained to patients, and written informed consent was taken. The first session (50 mJ), second (100 mJ), and third (150 mJ) were administered at 0.6 mm uniform spacing. Patients also agreed to a further 6‑months follow‑up. All nails were seen to show filling up of fenestrations before the next visit when new fenestrations were created. They also showed slow clearing with a distal clearing of the nails by the end of follow‑up. Although complete clinical clearance was not achieved even though direct microscopy and culture were negative at the end of follow‑up.

A peculiar yellowish discoloration was noticed after laser therapy, which could either be a result of the cumulative effect of laser (burn) or incomplete removal of nail lacquer due to a fenestrated surface. The other side effect was post-procedure deep‑seated pain in the great toenail subsequent to 150 mJ energy in the female patient. This pain was poorly responsive to analgesics and lasted about a week.

The results show that laser with topical therapy in OM is efficacious but not be as successful as projected or believed. The limitations include pre-existing laser systems which are nonoptimal for nails, lack of knowledge regarding the exact chromophore, difficulty in penetration of nail plate, nail plate acting as a fungal reservoir, and lastly, the thermal relaxation time of conidia and hyphae not being known.

To conclude fractional laser showed evidence of clinical improvement in dermatophyte distal and lateral subungual onychomycosis and may be considered as an adjuvant to increase the penetration of topical agents; however, its proposed fungicidal effect is questionable as higher energies required to achieve high enough temperatures for killing fungal elements may not be clinically tolerated and could damage the underlying nail bed.

Source- Grover C, Nanda S, Bansal S. Efficacy of fractional CO2 laser in onychomycosis: A clinical evaluation. Indian Dermatol Online J 2022;13:133-4.