Lamellar Keratoplasty

Abstract

I read with interest the article titled “Hyphal Growth Pattern and Recurrence of Fungal Keratitis after Lamellar Keratoplasty” by Xie et al.1Xie L. Zhai H. Shi W. et al.Hyphal growth pattern and recurrence of fungal keratitis after lamellar keratoplasty.Ophthalmology. 2008; 115: 983-987Abstract Full Text Full Text PDF PubMed Scopus (44) Google Scholar I have following comments on the article. In the series, 91.3% of cases infected by Fusarium had fungal filaments arranged horizontally, whereas 90.9% of Aspergillus cases had vertical orientation. We published histopathologic findings in 167 corneal buttons obtained on penetrating keratoplasty and found that nearly 76% cases had both horizontal and vertical orientation.2Vemuganti G.K. Garg P. Gopinathan U. et al.Evaluation of agent and host factors in progression of mycotic keratitis: a histological and microbiological study of 167 corneal buttons.Ophthalmology. 2002; 109: 1538-1546Abstract Full Text Full Text PDF PubMed Scopus (126) Google Scholar Furthermore, although 49% cases had diffuse distribution of fungal filaments, in 39% of these buttons the filaments were located only in anterior stroma, and in 12% these were restricted to posterior stroma. The distribution and orientation of fungal filaments had no correlation with genus. Because it is well known that distribution and orientation of fungal filaments in the cornea depends on many factors, I cannot understand why in the authors' series most corneal buttons (85%) had fungal filaments parallel to stromal lamellae. Some of the possibilities are:•Difference in sampling technique: Lamellar in contrast with full thickness in our series;•Method of assessing orientation: Sections showing both vertical and horizontal orientation (76% in our series) classified as either horizontal or vertical based on the predominant pattern; and•Stage of disease: Inclusion of cases with early disease as evident by surgery performed on cases with infiltrate size of 2 × 3 mm and not showing response to just 1 week of medical therapy. Although the results show that predominant pattern of fungal filament orientation with Fusarium was parallel (91%), whereas with Aspergillus it was vertical, the authors concluded that hyphal growth patterns in corneas seem to differ not only by genus, but also among the same species. The authors stated that recurrence rate was significantly more common in corneas infected with Aspergillus. If vertical orientation of fungal filaments is associated with high rate of recurrence, it is perplexing that, in the Aspergillus group, 10 of 11 cases (90% of 11) with vertical orientation recurrence was seen in only 4 cases (40%), compared with 11 of 13 (84.7%) cases in the Fusarium group. Because the sample size of the Aspergillus group is too small to draw any conclusions, care must be taken before making the statement that Fusarium a had low rate of recurrence compared with Aspergillus. Author replyOphthalmologyVol. 116Issue 2PreviewWe appreciate the interest and comments from Dr Garg regarding our article on hyphal growth patterns and recurrence of fungal keratitis after lamellar keratoplasty.1 The growth patterns of fungal pathogens in corneas in our study differ from what was reported by Vemuganti et al,2 which may in part be explained by different evaluation criteria for hyphal directions. It is common that both horizontally and vertically growing hyphae are found in one corneal button. However, the criteria we used were based on the majority of fungal filaments, not all of them. Full-Text PDF