Histopathologic Findings in Corneal Buttons of Keratoconus Patients: A Comparison With Topographic Indexes

Abstract

Purpose: : To describe the histological findings of corneal buttons from Mexican patients diagnosed with keratoconus and analyze if there is an association with topographic indexes described as characteristic of the disease (figure1). To describe demographic distribution of keratoconus in Mexico, and analyze associated risk factors such as age and gender. To establish criteria regarding a possible surgical indication based on topographic image.

Methods: : Observational, transversal, descriptive and comparative study with correlation of image and histology.Data was collected from the records of patients diagnosed with keratoconus who had corneal topography previous to penetrating keratoplasty.Histological description of the corneal buttons. We made a computation of relative risk organizing and comparing data in 2 x 2 tables. Descriptive statistics were made with SPSS v.015. We measured the pachymetry on the histological specimens and compared it with the one reported on the image study.

Results: : We found 1200 reports of corneal buttons. Keratoconus is more prevalent among the young male population of central Mexico. 69 % of the complete files had incomplete Bowman, 69.8 % stromal thinning and relative risk of 6.85 times more possibility of leucoma. In contrast 85.2 % had no creases or break in Descemet with 5.37 relative risk times more possibility of no break in the presence of corneal leucoma. Corneal topography is reliable measuring corneal thickness, it relates with histological findings. Keratometrys less than 55 dioptrys had less chance of having incomplete Bowman (relative risk 0.51). We found a relationship between bowman rupture and presence of corneal leucoma and high keratometrys (above 55 dioptrys). These data could place the pathophysiology of the disease in the most anterior levels of the stroma. It has been reported by confocal microscopy that nor the descemet membrane and the endothelium suffer damage, here we see the majority of histological sections to support this assertion.

Conclusions: : Descemet membrane rupture and the endothelium probably not play a decisive role in the physiopathogeny of disease.keratometries in excess of 55 D are associated with shrinking, presence of leucoma and breakdown of Bowman; this image parameter could be considered an indication for realization of penetrating keratoplasty.

Keywords: keratoconus • clinical (human) or epidemiologic studies: systems/equipment/techniques • imaging/image analysis: clinical