Comparison of smear positivity from anterior and posterior (endothelial) corneal scrapings obtained per-operatively in patients undergoing therapeutic penetrating keratoplasty – A retrospective study
Pankti C Buch, Shashwat Shekhar, Sujata Das, Nandu Prakash, Deepa Kumari, Vanya Singh, Amber Prasad, Neeti Gupta, Sanjeev K MittalPurpose:
To compare the microbiological positivity of corneal smears obtained from the anterior corneal surface and the posterior (endothelial) surface of the excised corneal button in patients undergoing therapeutic penetrating keratoplasty (TPK).
Methods:
This retrospective study included patients who underwent TPK between August 2019 and January 2025 at a tertiary care center. Demographic and clinical details were retrieved from hospital and eye bank records, while microbiological data were obtained from the microbiology department. Intraoperative corneal scrapings were collected from the anterior corneal surface prior to trephination and from the posterior (endothelial) surface of the excised recipient corneal button. Smears were examined using standard staining techniques. Patients with incomplete microbiological data or noninfective indications were excluded. Microbiological findings from anterior and posterior samples were compared using the Chi-square test, with
Results:
Of 252 TPKs performed, 132 patients met the inclusion criteria. Trauma was the most common predisposing factor (44.5%). Anterior corneal scrapings were positive in 26.5% (n = 35) of cases, with fungal elements predominating (74.3%), followed by Gram-positive cocci and Gram-negative organisms. Posterior (endothelial) scrapings showed a higher positivity rate of 34.8% (n = 46), with fungi accounting for 89.1% of positive samples. Both samples were negative in 51.5% of cases. Posterior scrapings demonstrated significantly higher positivity than anterior scrapings (
Conclusion:
Posterior corneal (endothelial) scraping yields higher microbiological positivity than conventional anterior scraping and serves as a valuable adjunct. Combining both techniques may enhance pathogen detection in advanced infectious keratitis.