Topography and Tomography Findings in Patients With Down Syndrome

To my knowledge, the Down syndrome (DS) study by Alio and colleagues¹ is the first to use corneal topography/tomography (Sirius System [Costruzione Strumenti Oftalmici] shape indices, aberrometry, pachymetry, and simulated keratometry), axial length, and biomechanical testing on a large cohort of patients with genetically confirmed DS. Two groups were tested: a cooperative group of 113 eyes of 59 participants who permitted the previously mentioned testing , and an uncooperative group of 103 eyes of 53 participants for whom testing could not be performed. A control group was selected at random from corneal refractive surgery candidates. Only those cases labeled as normal by the Sirius System within the group with DS were compared with the topographic findings in the control group. Three topography reading centers described 3 categories of normal, abnormal, and undeterminable topography maps within cooperative patients with DS. Abnormal topographical patterns were defined based on keratoconus Rabinowitz patterns (presence of an asymmetric bowtie, inferior steepening, skewed radial axis, or asymmetric bowtie with skewed radial axis pattern).² Undefined cases were those in which a topographic analysis could not be performed mainly because of poor cooperation. The severity of those cases typified as abnormal were classified according to the degree of comalike aberrations.³ The abnormal group was determined to have all 4 of the Amsler classifications⁴ of keratoconus (KC). The healthy group of patients and eyes with DS comprised 38 eyes of 26 participants (mean [SD] age, 19.9 [11.32] years) and was found to differ from a non-DS group of healthy control eyes in visual acuity components (uncorrected distance visual acuity and best-corrected distance visual acuity), orthogonal components of anterior and posterior corneal shape (simulated mean keratometry values in flat and steepest meridians), and values of corneal shape in the anterior and posterior corneal surfaces. These 2 groups did not differ in refractive errors. In addition, significant differences in corneal aberrometric parameters (primarily coma) were found in most of the Zernike components that were analyzed for both anterior and posterior surfaces. To my knowledge, this is the first article to describe the high incidence of coma in eyes with DS.