ASTIGMATISM MANAGEMENT BY SHORTENING ALLOGENIC CORNEAL RING SEGMENTS IN KERATOCONUS

To show the effectiveness of shortening corneal allogenic ring segment on astigmatism

Department of Ophthalmology, Istanbul Medipol University, Istanbul, Turkey

A 30-year-old male presented with a moderate keratoconus in his right eye. Uncorrected and best corrected visual acuities(UCVA and BCVA) were 0.4(decimal Snellen). Two symmetrical 160-degree arcs of allogenic corneal ring segments(Keranatural) were implanted by using femtosecond laser channel creation.  Tunnel size and depth were 4x7,5 mm and 250 microns.  One month after the operation, there were decrease in K1 and K2 values from 45.2D and 52.6D to 34D and 43.1D, respectively. UCVA and BCVA were worsened to 1-meter finger count. Due to high corneal astigmatism, a second surgery was planned for shortening the ring segments as allogenic ring segment can be cut easily. Both segments were shortened by approximately 50 degrees. The patient's UCVA increased to 0.4 and BCVA to 0.7 (+3.00 DS/0 DC) in the first month after shortening. K1 and K2 values were 38.5D and 44.5D, respectively.

Since allogenic corneal ring segments are soft, elastic and adjustable tissues, patient outcomes can be managed with enhancement operation.  High corneal astigmatism in keratoconus patients can be treated by using shorter arc (around 110 degrees) to create a local flattening effect easily.