Effects of systemic isotretinoin therapy on tear function and choroidal thickness in nodulocystic acne patients: a prospective comparative study.

PURPOSE: This research intended to assess how systemic isotretinoin therapy influences subfoveal choroidal thickness (CT) along with superficial (SVD), deep (DVD), and choriocapillaris (CCD) vascular densities in nodulocystic acne patients, utilizing optical coherence tomography angiography (OCTA).

METHODS

This prospective, non-randomized comparative study was conducted between April 2024 and July 2025. It included 32 patients with nodulocystic acne who completed a six month course of systemic isotretinoin (Group 1) and 28 patients with nodulocystic acne who did not receive systemic treatment (Group 2). In both groups, SVD, DVD, CCD and subfoveal CT data were obtained using OCTA. All patients underwent the Schirmer test. A post hoc power analysis was performed with G Power software. Data were analyzed with SPSS version 27.0. A p value below 0.05 was considered significant, and a Bonferroni corrected threshold of 0.01 was additionally applied across the five primary between group comparisons.

RESULTS

In Group 1, the average treatment duration was 5.66 ± 1.10 months, with a mean isotretinoin dose of 33.44 ± 10.66 mg/day, the mean cumulative dose was 98.6 ± 44.7 mg per kg. Mean CT was 314.75 ± 55.72 μm in Group 1 and 282.70 ± 48.46 μm in Group 2. This difference was statistically significant (p = 0.022) but did not meet a Bonferroni corrected threshold of 0.01 applied across the five primary comparisons. SVD, DVD, CCD did not differ significantly between groups (p > 0.05). Within Group 1, cumulative isotretinoin dose showed a positive correlation with CT (Spearman rho = 0.403,p = 0.022), which also did not meet the stricter correction threshold used for the correlation analyses. Mean Schirmer values were 14.27 ± 6.76 mm in Group 1 and 20.38 ± 6.71 mm in Group 2. This difference was statistically significant and remained significant after Bonferroni correction (p < 0.001). In Group 1, longer treatment duration was associated with lower Schirmer values within a multivariate model that also included age and drug dose (B=minus 2.96,p = 0.009), although the overall model approached but did not reach the conventional significance threshold (p = 0.055).

CONCLUSIONS

Systemic isotretinoin treatment was associated with a significant reduction in basal tear secretion. CT was significantly greater in the treated group at a conventional significance threshold, with a positive correlation to cumulative drug exposure, although neither finding survived correction for multiple comparisons. No significant differences were found in the retinal vascular density parameters assessed. The results of the study should be interpreted with appropriate caution and considered together with hypotheses for future confirmation.

TRIAL REGISTRATION: (NCT07675460) (29.06.2026). Because this was a nonrandomized observational comparison rather than a clinical trial, registration was retrospective and occurred after study completion.