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To characterize higher-order aberrations (HOAs) in clinical and subclinical keratoconus (KC).The study included 33, 36, and 26 patients with clinical, topographic (no clinical signs), and pretopographic (normal topography and no clinical signs) KC and 30 controls. Ocular and corneal HOAs for the 4-mm pupils were measured using a wavefront sensor and expanded up to the sixth order of Zernike polynomials. The magnitudes of trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration were calculated via Zernike vector analysis and used as HOA parameters along with total HOAs. Area under the receiver operating characteristic curve (AUROC) values for each wavefront parameter for pretopographic KC were compared.Control eyes and eyes with pretopographic KC had significantly lower ocular or corneal total HOAs and Zernike vector terms than those with clinical KC and topographic KC, except for ocular tetrafoil between topographic KC and pretopographic KC and spherical aberration among all groups. The AUROCs for corneal total HOAs and corneal coma for pretopographic KC and control eyes were 0.781 (100% sensitivity and 47% specificity) and 0.735 (73% sensitivity and 73% specificity), respectively.Corneal total HOAs and corneal coma exhibited a potential ability to discriminate pretopographic KC from normal control eyes.

PURPOSE To characterize very asymmetric keratoconus (KC) in terms of clinical demographics and risk factors in the Japanese population. METHODS We retrospectively reviewed the clinical records of patients with very asymmetric KC attending a university hospital. Patients with very asymmetric KC had defined clinical KC in one eye and normal topography in the fellow eye. All patients completed a questionnaire on potential risk factors (family history of KC, atopy, asthma, allergy, heart disease, sleep apnea, Down syndrome, eye rubbing, prone sleep position, and dominant hand). These data were compared with those of patients with clinical or topographic KC in both eyes. Subgroup analysis of very asymmetric KC eyes were performed based on the KC status: mild and severe. RESULTS We retrospectively investigated 66 patients with very asymmetric KC and 505 patients with KC. Patients reported eye rubbing (53%-56%), allergy (62%-63%), and atopy (28%-29%) in both groups. There was no significant difference in terms of risk factors between the two groups. Approximately half of the 66 patients with very asymmetric KC had KC eyes ipsilateral to the dominant hand. Subgroup analysis of very asymmetric KC showed that atopy and asthma were more frequent in the mild KC group than in the severe KC group. Forty-four of 60 patients (73.3%) were using corneal, rigid, gas-permeable contact lenses (corneal GPs) for the KC eye, of which 30 patients (68.2%) were also using a corneal GP for the fellow eye. CONCLUSIONS The patient-reported frequency of eye rubbing, allergy, and atopy were similar between KC and very asymmetric KC. Furthermore, we found no association between hand dominance and KC laterality.