Gender differences in keratoconus keratoplasty: a 25-year study in Southern Brazil and global perspective.

PURPOSE: To compare the characteristics and outcomes of male and female patients that underwent corneal transplantation for keratoconus (KC) in Southern Brazil and worldwide.

METHODS: Retrospective longitudinal study that evaluated medical records of patients who were submitted to keratoplasty between August 1990 and September 2015 in two tertiary hospitals in the state of Rio Grande do Sul (Brazil) and review of the Medline and Embase database international literature.

RESULTS: Out of a total of 4026 corneal transplants at that period, 1284 patients (1530 eyes) received preoperative diagnosis of KC (31.8%). A total of 839 men underwent keratoplasty for KC (65.4%) with mean age of 30.3 (±12.2) years. The 445 transplanted women (34.6%) had a mean age of 34.5 (±14.8) years. Both differences were statistically significant (p < 0.01). Regarding laterality, skin color, recipient and donor cornea trephination diameter, and rejection episodes there was no significant difference between the two groups at baseline (p > 0.05). Females were submitted significantly more to deep anterior lamellar keratoplasty (DALK) in comparison with males (26.5 vs. 15.7%, p < 0.01). We were able to include 57.4% of the original keratoplasties for our follow-up data analysis. Male sex and penetrating keratoplasty (PK) were associated significantly with increased risk for graft failure in KC transplantation at the end of follow-up (p < 0.05). The mean follow-up of transplanted patients was similar in both groups.

CONCLUSION: Keratoconus is the most transplanted corneal disease in Southern Brazil and globally. Studies in Africa, Asia, Europe and North America also showed gender differences in KC patients submitted to keratoplasty. We found that men were transplanted in a 1.9 male/female ratio and at an earlier age than women. At final follow-up, male sex and PK were risk factors associated with increased graft failure. It is essential to broaden the hormonal and genetic investigations to elucidate why keratoconic males have undergone more keratoplasties and have more secondary failure than females.