TBCE and keratoconus: In fact the total number of KCs labeled by five non-overlapping split-GAL4 lines – MB131B, MB370B, MB371B, MB185B and MB594B – is very close to the estimated total number of KCs (1,855 vs. 2,000; Aso et al. 2014a), making it unlikely that any major KC subtype is missed.