The eye is like an under-inflated balloon: the low pressure inside allows it to absorb most jabs without being punctured. It is much tougher to pop an under-inflated balloon with a pencil compared to a maximally-inflated one. This means that for ocular surgery we need exquisitely sharp blades to penetrate the eye. And it’s the reason why we love diamond keratomes so much; they are much sharper than even the best steel blades.
In the case shown here, the tip of the paracentesis blade is ever so slightly bent, likely from something innocuous like simply letting the tip touch something such as the assistant’s table or Mayo stand. Because these blades are so sharp, by necessity, they are also very delicate. The best option is to leave the blades in their protective covers until just prior to their use.
In the eye, this bent tip makes it difficult to create the paracentesis and the tunnel length of the incision becomes longer than anticipated. In order to prevent being oar-locked, we intentionally enlarge the incision on the way out. Fortunately, in this case, the keratome is still in perfect condition and the main phaco incision (which is far more important) is great.
In addition, we use the keratome to make a paired, full-thickness incision directly opposite the main incision to help address the against-the-rule astigmatism which is at about the 165 degree mark.
Click below to learn from this video about the effect of a bent tip on the blade: