Results of contralateral Athens and decentered individualized sphero-cylindrical (DISC) protocols for keratoconus management.

Purpose: To present the results of two different surgical procedures, decentered individualized sphero-cylindrical protocol (DISC protocol) and Athens protocol, performed on a 34-year-old patient after being diagnosed with keratoconus in both eyes. Observation: The patient's left eye was subjected to the Athens protocol (phototherapeutic keratectomy (PTK) + partial topo-guided photorefractive keratectomy (TG-PRK) + corneal cross-linking (CXL)). In contrast, the patient's right eye was subjected to the DISC protocol (PTK + DISC excimer ablation + CXL). After administration of topical anesthetic, the patient was subjected to PTK of the central 7 mm optical zone with 50 µm depth of epithelial ablation. After excimer laser ablation in both eyes, riboflavin 0.1% solution was applied topically every 2 minutes for 20 minutes. This was followed by five cycles of 5-minute-long irradiation (for 25 minutes) using a UVA 370 nm at 3.0 mW/cm2 CXL (CSO VEGA CMB X Linker, Florence, Italy) application. 36 months postoperative uncorrected visual acuity (UCVA) of the left eye remained the same as preoperatively, while the best corrected visual acuity (BCVA) was -3.5 Dsph=20/30. In the right eye, UCVA and BCVA were both 20/22. Results of Fourier's analysis of the right eye imply a 52% decrease in corneal irregularity, while in the left eye, corneal irregularity decreased by 12.8%. Values of spheric aberration in Zernike analysis 36 months postoperatively showed a lower increase in Athens protocol than DISC protocol. The index of vertical asymmetry and the index of surface variance showed lower values in both procedures during the whole postoperative period, while the index of height decentration showed a more significant decline in Athens protocol 36 months postoperatively. Conclusion and importance: DISC protocol is a novel approach, with the potential to become a promising strategy for slowing the progression of keratoconus and recovering uncorrected visual abilities.