New Formula to Calculate the Size of the Corneal Flap for Autologous Ipsilateral Rotational Keratoplasty
Abstract
A new formula for autologous ipsilateral rotational keratoplasty has been designed and verified by surgical procedure on 19 eyes. The formula is found to be successful in all cases. The diameter (D) of the cornea to be rotated is equal to the length of scar from one side of pupillary margin in semidark room, nearest to the scar to the farthest end of the scar (L) nearest to center of pupil, added to the pupillary diameter (Pd) in semidarkness. The direction of rotation of scar is just opposite of radius under consideration and off center by 0.5mm (trephine is put on 0.5mm outside the pupillary margin.
D=L+Pd
Minimum clear cornea required for rotational flap is 4 mm on one side of the pupil. In eyes with eccentric corneal opacities partially involving the pupillary area, using a rotational corneal autograft, can revitalise vision. This procedure does not warrant immunological rejection associated with allografts.
Keywords
Download Options
Introduction
Many erudite authors have prescribed formulae for this purpose. But two of them shall be discussed in the chapter for discussion, as it is commonly used. Formula have been described that help assess the suitability of the procedure and choose the size of the trephine to be used. The use of digital photographs and imaging software to assess the suitability of the procedure has also been described by other learned authors[1,2,3] . This is a procedure that works best in eyes that have a central corneal opacity and clear peripheral cornea. An eccentric trephination is performed that allows the removal of disk of cornea containing the central opacity.
Various methods have been described for these calculation[4,5] .
Conclusion
The new formula for autologous ipsilateral rotational keratoplasty is shown below
D=L+Pd
Which is very simple and verified by surgical procedure on 19 eyes.
It is expected to give successful result with suturing at differential thickness of cornea as thickness of new alignment is not equal.