Intrastromal Ring Segments for Keratoconus: A Retrospective Review Brad Feldman MD, Alan Carlson MD, Terry Kim MD, Natalie Afshari MD, Ricardo Santaella MD Duke Eye Center Authors Have No Financial Interest in this Study

Purpose : To determine the clinical outcomes of patients receiving intrastromal ring segments (Intacs, Addition Technology, Inc) for keratoconus at the Duke Eye Center Only included patients with keratoconus Excluded patients with any prior surgery Outcome Measures: –Visual Acuity –Contact Lens Tolerance –Refraction –Corneal Apex Decentration –Keratometry –Complications

Methods Retrospective chart review of all patients with adequate follow-up who received intrastromal ring segments for keratoconus from at Duke Primary outcome measures: –Uncorrected distance visual acuity (UCDVA) –Best-corrected distance visual acuity (BCDVA) –Contact lens tolerance

Methods Secondary outcome measures : –Corneal apex decentration As determined by Pentacam imaging (Oculus) – Simulated keratometry As determined by Humphrey Atlas topography (Carl Zeiss Meditech, Inc) –Complications –Patient satisfaction

Results 31 eyes of 26 patients Patient Characteristics –Pre-op indications for surgery: All complaining of poor best-corrected vision Zero satisfied in contact lens wear –Average Age = 40 –Mean Pre-op Pachymetry = 473

Results UCDVA (LogMar) Mean SD –Pre-op:1.40+/-0.61 –POM#1:0.83+/-0.46 –Last Visit*:0.80+/-0.34 This was approximately 6 lines of improvement BCDVA (LogMar) Mean SD –Pre-op: 0.33+/-0.28 –POM#1:0.33+/-0.26 –Last Visit*:0.23+/-0.20 This was approximately 1 line of improvement *Last visit on average was 7.5 months post-procedure

Results Contact Lens Intolerance –Pre-operative: 100% (28/28) –Post-operative:22% (5/23) Note: The discrepancy in eyes is because 3 patients were unwilling to try contact lenses pre-operatively and 8 patients had not yet been fit for contact lenses post-operatively

Contact Lenses Pre & Post Intacs

Effect of Intacs on Refraction

Change in K Values

Pentacam Apex Decentration Mean SD Pre-op1.21 +/-0.69 Post-op0.84+/-0.38 Mean Change in LogMar BCDVA if: –Less Decentered Post-Intacs: 0.00 –More Decentered Post-Intacs:+0.24

Summary Average of 6 line UCVA improvement Average of 1 line BSCVA improvement Significantly improved CL tolerance Flattens cornea about 5 diopters Mild reduction of sphere and cylinder Safe and reversible