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Fig. 5. Back vertex distance (BVD) as a function of entry position of an
HeNe laser beam into the (A) right (1.65 mmx1.88 mm diameter) and
(B) left (1.63 mmx1.85 mm diameter) lens of a Pterygoplichthys
etentaculus individual. The triangles represent individual data points,
and the solid lines represent fitted non-linear regression lines [(A)
x=2.50-0.92y2+0.80y4; (B)
x=2.44-0.68y2+0.55y4]. The
beam-entry positions have been normalised so that the edges of the lens
represent 1 and -1.