Acne vulgaris is one of the most prevalent dermatological conditions, particularly among adolescents and young adults. Though the active lesions are temporary, they often heal with residual scarring that can be disfiguring and persistent.1,2 Atrophic acne scars manifest due to collagen loss during wound healing and are classified into icepick, rolling, and boxcar types. These scars not only pose cosmetic concerns but also contribute significantly to psychological distress, lowering self-esteem and quality of life in affected individuals.2,3

Numerous treatment modalities have been employed to address atrophic acne scars, including chemical peels, dermabrasion, subcision, fillers, microneedling, and laser therapies.4,5 Among these, fractional carbon dioxide (CO₂) laser resurfacing has emerged as a promising ablative technique that delivers focused thermal injury to induce collagen remodelling and tissue regeneration.6 Microneedling, conversely, is a minimally invasive, cost-effective procedure that stimulates neocollagenesis through controlled dermal injury using fine needles. Both techniques have shown favourable outcomes in scar improvement, but their comparative effectiveness and safety remain areas of ongoing research.

Both fractional CO₂ laser and microneedling have significantly improved atrophic acne scars, with most studies supporting their effectiveness across different scar types and skin tones.8-13 Fractional CO₂ laser generally demonstrates slightly superior clinical outcomes, particularly for rolling and boxcar scars, due to its deeper dermal remodelling effect. However, it is often associated with longer downtime and a higher risk of post-inflammatory hyperpigmentation, especially in darker skin types.8-11 Microneedling, whether used alone or combined with PRP, is considered a safer and more cost-effective alternative, offering shorter recovery and better tolerability with fewer pigmentary side effects.9-11 Overall, both modalities are effective, and patient satisfaction remains high, but individual scar morphology, skin type, and tolerance to downtime should guide treatment selection.8,9,12-14

Although fractional CO₂ laser and microneedling are widely used for treating atrophic acne scars, there is still no explicit agreement on which method is more effective, especially in Indian patients with darker skin types. Many previous studies had small sample sizes or used different ways to measure improvement, making it hard to compare results. Also, there is limited data from studies done in real-world clinical settings in our population. Therefore, this study was planned to directly compare the results of these two treatments using the same evaluation method to help choose the better option for scar management. The present study aims to compare the clinical efficacy and safety of fractional CO₂ laser and microneedling in treating atrophic facial acne scars, focusing on scar improvement, adverse effects, and overall patient tolerability.

Study Design and Setting:

This study was conducted as a prospective, comparative interventional trial in the Department of Dermatology at a tertiary care teaching hospital over 18 months. Institutional Ethics Committee approval was obtained before initiation and informed written consent from all participants before enrollment.

Study Population:

Fifty patients between 18 and 35 years of age with atrophic facial acne scars were recruited from the dermatology outpatient department. Inclusion criteria comprised patients with Goodman and Baron grade 2 or 3 acne scars and Fitzpatrick skin types III to V, with a history of being acne-free for at least six months. Patients were excluded if they had active acne, a history of keloid formation, ongoing systemic illness such as diabetes or immunosuppression, photosensitive disorders, recent use of isotretinoin within six months, or prior laser/microneedling treatment. Pregnant or lactating women were also excluded from the study. Sample Size and Sampling: Fifty participants were enrolled, and the sample was equally divided into two groups of 25 each. Simple random sampling using the sealed envelope method was employed to assign patients to either of the two treatment groups.

Study Groups with Intervention Protocols:

Group A participants received four fractional CO₂ laser therapy sessions at monthly intervals. All patients underwent a two-week priming period with sunscreen and a depigmenting agent. On the day of the procedure, topical anaesthetic cream (a eutectic mixture of lidocaine 2.5% and prilocaine 2.5%) was applied for 45 minutes. The fractional CO₂ laser (10,600 nm) was delivered with energy parameters ranging from 20 to 40 mJ, pulse duration between 600–800 microseconds, and 100–150 MTZ/cm² density. Treatment involved a single or double pass, depending on the severity of the scars. Post-procedure care included topical antibiotic cream and sun protection.

Group B patients were treated with microneedling using a dermaroller fitted with 192 needles 1.5 mm long. The same priming and anaesthesia protocol was followed. The dermaroller was applied vertically, horizontally, and diagonally across the scarred area until uniform pinpoint bleeding was achieved. Patients were then advised topical antibiotics and strict photoprotection.

Follow-up: Each patient received four treatment sessions spaced one month apart. Follow-up visits were conducted one month and two months after the final session. Clinical improvement, adverse events, and patient satisfaction were documented at each follow-up.

Outcome Variables:

The primary outcome was the degree of scar improvement assessed by the Goodman and Baron Qualitative Scar Grading System. Secondary outcomes included patient-reported satisfaction measured on a 0–10 Visual Analogue Scale (VAS) and documentation of any adverse effects such as erythema, oedema, post-inflammatory hyperpigmentation, pain, and duration of downtime.

Data Analysis:

Data were compiled in Microsoft Excel and analyzed using SPSS software version 25. Continuous variables were presented as mean ± standard deviation, while categorical variables were expressed as frequencies and percentages. The paired t-test was used to compare pre-and post-treatment outcomes within each group, and the unpaired t-test or Mann–Whitney U test was used for between-group comparisons. A p-value <0.05 was considered statistically significant.

RESULTS

As per Table 1, both treatment groups were well-matched regarding clinico-demographic characteristics, with no statistically significant differences observed. The mean age of participants was comparable between the CO₂ laser group (25.8 ± 4.2 years) and the microneedling group (26.3 ± 3.9 years). Gender distribution was nearly equal in both groups, and most patients belonged to Fitzpatrick skin types III and IV. The average scar duration was also similar, indicating homogeneity in baseline characteristics and minimizing confounding variables.

Table 1: Clinico-demographic Profile of Study Participants (n = 50)

Table 2 displays the distribution of scar severity based on the Goodman and Baron grading system at baseline. Both groups had a nearly identical proportion of Grade 2 and Grade 3 atrophic scars, with Grade 2 scars present in 56% of the CO₂ laser group and 52% of the microneedling group. This uniform distribution supports the validity of outcome comparisons, as initial scar severity was consistent across the two cohorts.

Table 2: Scar Grade Distribution at Baseline

Table 3 presents the core clinical and subjective outcomes following treatment. A high proportion of patients in both groups experienced at least one grade of scar improvement, with a slightly higher response in the CO₂ laser group (84%) compared to the microneedling group (72%). However, more patients in the CO₂ laser group showed a two-grade improvement (16% vs. 12%), though the difference was not statistically significant. Patient satisfaction scores were also marginally higher in the laser group (mean VAS 7.8) versus microneedling (mean VAS 7.5), reflecting similar levels of perceived benefit.

Table 3: Comparison of Clinical and Subjective Outcomes

Table 4 highlights differences in safety and tolerability outcomes between the two modalities. Post-inflammatory hyperpigmentation was significantly more common in the CO₂ laser group (20%) than microneedling (4%), indicating a higher risk of pigmentary changes with laser therapy. Downtime of more than three days was also more frequent in the laser group (40% vs. 16%), suggesting a more extended recovery period. Additionally, the mean pain score was notably higher in patients undergoing CO₂ laser treatment (5.6 ± 1.3) than those treated with microneedling (4.1 ± 1.1), with a statistically significant difference. These findings emphasize the superior tolerability and reduced side-effect profile associated with microneedling.

Table 4: Adverse Effects and Downtime Profile

Acne vulgaris is a highly prevalent dermatological condition that often leaves behind atrophic scars, which can impact both physical appearance and psychological well-being. These scars—commonly classified into icepick, rolling, and boxcar types—are challenging to treat due to their depth and varied morphology. With advancements in dermatologic interventions, fractional CO₂ laser and microneedling have become effective modalities for acne scar revision. The present research sought to compare these two treatments in terms of efficacy, safety, patient satisfaction, and tolerability in a matched population.

In our study, both groups were well-matched concerning age, gender distribution, skin type, and duration of scars, ensuring comparability. Similar demographic profiles were observed in studies conducted by Agrawal et al.8 and Rajput et al.,11 where most patients belonged to Fitzpatrick skin types III to V and were in their twenties. This demographic trend highlights the importance of using treatment modalities that are not only effective but also safe for darker skin types that are at higher risk for pigmentary complications.

Regarding baseline scar severity, our study included a balanced distribution of patients with Goodman and Baron Grade 2 and Grade 3 scars in both groups. This alignment with prior studies by Saoji et al.12 and Abel et al.14 allowed for an unbiased comparison of treatment outcomes. Consistent scar grading between groups is essential, as initial severity can significantly influence the degree of visible improvement.

The findings of our study revealed that both treatments led to clinically significant improvement in scar appearance, with a slightly greater proportion of patients in the fractional CO₂ laser group achieving a two-grade improvement. These observations are comparable to those reported by Patil et al.9 and Abel et al.,14 who also found better scar grade reduction with CO₂ laser, albeit with a marginal difference. However, Rajput et al.11 and Reddy et al.10 found comparable clinical efficacy between fractional CO₂ laser and microneedling modalities, indicating that the superiority of one treatment over another may depend on scar morphology and treatment protocol. In terms of subjective satisfaction, the results in our study showed slightly higher scores in the laser group, although the difference was not statistically significant. This is in line with the findings of Patil et al.,9 who reported comparable patient-reported outcomes for both methods, reinforcing that microneedling is a viable alternative to more aggressive laser procedures.

A notable observation from our study was the higher incidence of post-inflammatory hyperpigmentation and prolonged downtime in patients treated with fractional CO₂ laser. These outcomes are consistent with those of Agrawal et al.8 and Reddy et al.,10 who reported greater pigmentary side effects and longer recovery in the laser group. Conversely, microneedling showed better tolerability, with fewer adverse events and faster recovery time, making it more suitable for patients concerned about social downtime or complications. Rajput et al.11 also emphasized this advantage, suggesting that microneedling may be more appropriate in individuals with darker skin tones prone to pigmentary changes.

Limitations:

The study was limited by a relatively small sample size and short follow-up duration, which may not capture long-term outcomes or recurrence. Histopathological evaluation was not performed to support clinical findings. The study was also single centre, which may affect generalizability.

Both fractional CO₂ laser and microneedling effectively improved atrophic acne scars, with the laser showing better clinical outcomes and microneedling demonstrating superior safety and tolerability. Given its lower risk of pigmentary changes and shorter downtime, microneedling may be recommended as the preferred first-line option for patients with darker skin types, while fractional CO₂ laser can be reserved for cases needing more aggressive scar remodelling. Future multi-centre trials with larger cohorts and histological assessments are recommended to validate these findings.

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