AIM:To study the relationship between astigmatism and keratoconus by using Pentacam anterior segment analyzer.

METHODS:Totally 88 patients(93 eyes)with early keratoconus were divided into clinical keratoconus group(43 cases, 46 eyes)and subclinical keratoconus group(45 cases, 47 eyes)according to related standards. Meanwhile, 40 patients(41 eyes)with history of myopia and astigmatism(astigmatism ≥2.0D)were recorded as the control group. The keratoconus index(KI), corneal index of surface variance(ISV)and index of vertical asymmetry(IVA)were determined using Pentacam anterior segment analyzer, and their diagnostic value for keratoconus was analyzed.

RESULTS:The parameters of Pentacam anterior segment analyzer were different among the three groups(P<0.05). Rmin was the highest, and other parameters were the lowest in the control group. Rmin was lower, and other parameters were higher in the clinical keratoconus group than in the subclinical keratoconus group(P<0.05). The area under curve(AUC)values of ISV, KI, IVA, index of highest decentration(IHD), aberration coefficient(ABR), corneal anterior surface maximum keratometry(Kmax), posterior corneal surface elevation(PE), minimun radius of curvature(Rmin)and corneal anterior surface elevation(AE)in the diagnosis of clinical keratoconus were 1, 1, 1, 1, 0.950, 0.919, 0.951, 1 and 0.992, with good sensitivity and specificity. IVA, Rmin, AE, and PE had better sensitivity and specificity in the diagnosis of subclinical keratoconus. The AUC values were 0.927, 0.923, 0.954, and 0.947, respectively.

CONCLUSION:Pentacam anterior segment analysis system has great value in early diagnosis of keratoconus.