In addition to minimal or no treatment zone on fluorescein pattern analysis, the lens will often decentre inferiorly and there may be large bubbles in the
reverse curve. Topographically, a steep, low riding lens will produce either a minimal treatment zone or a 'frowny face' pattern (see Figure 7b).
The Synergeyes PS lens is a hybrid design with a
reverse curve RGP centre, which can be very useful in fitting oblate corneas, provided that the donor graft diameter is less than the RGP centre, ie smaller than 8.4mm.
Each base curve has three 'lift' options, which is effectively the amount of
reverse curve the lens has, with Lift 1 or 'L1' having the gentlest curve for mildly oblate corneas, and L3 having the most rapid steepening towards the edge, for more severe cases (Figure 3).
Van Cauter noted that sharply rising curves in the prevalence of obesity in the United States since the 1960s mirror
reverse curves in the amount of sleep Americans get--the smallest amount in the industrialized world.
"You have to [drive] across your neighbors' driveway to get into your garage, so you have two
reverse curves crossing.
Between blue and nickel, it seems any imperfections always show up on a nickel gun--and always in those hard-to-reach places such as the cylinder crane, where the barrel meets the frame and around the
reverse curves of the trigger guard.