Patient Reported Outcomes after Wavelight^® Topography-Guided CONTOURA^® Vision LASIK using Phorcides^

Wavelight^® Topography-Guided CONTOURA^® Vision LASIK

Wavelight CONTOURA^® Vision is a topography guided (TG) LASIK treatment that takes into account the shape of the anterior corneal surface and uses corneal height data from the corneal topography measures that are taken prior to surgery. These treatment profiles help manage higher order aberrations (including spherical aberration) of the cornea by compensating for cosine effect and by normalizing or ‘smoothing’ the overall surface of the cornea to improve its regularity. When these changes are made to smooth out the elevations on the cornea, it changes the overall refractive correction needed and may not match the original manifest refraction. This means that tweaks in the spherical and/or astigmatism components of the manifest refraction inputs will likely need to be changed when determining the final treatment calculation for CONTOURA^® Vision. These changes can be done manually by the surgeon more or less guessing what the required change should be or, instead, the surgical planning can be simplified by using special software called Phorcides^. This software calculates the exact treatment profile required without manual input from the surgeon and takes the guesswork out of TG CONTOURA^® Vision LASIK treatment planning.^1,2

Phorcides^ Analytic Engine Software

The Phorcides^ software objectively determines the required treatment profile. It takes into account not only the anterior corneal astigmatism and the anterior topography irregularities that cause higher order aberrations but also posterior corneal astigmatism and lenticular astigmatism.²

Phorcides^ uses geographic imaging software to analyze the anterior topographic profile of an individual’s cornea. It takes into account anterior topographic data from the Placido Disc-based Topolyzer^® Vario, along with anterior and posterior corneal astigmatism data from a Scheimpflug topographer. The Phorcides^ software measures the radius of each raised topographical feature, or talus, and uses all this information to determine the true anterior corneal astigmatism. The software compiles a series of refractive vectors: one vector for each raised topographic feature on the corneal surface, one for the anterior corneal astigmatism, one for the posterior corneal astigmatism, and one for any internal lenticular astigmatism. Finally, it uses a series of advanced computer algorithms to determine an optimized sphere and cylinder magnitude and orientation for the treatment.²

This more objective approach allows the treatment planning to be more efficient and the Phorcides^ software has shown improved vision outcomes compared to manual treatment planning, particularly at the 20/15 and better level.^2,3

Clinical Study Assessing Patient Reported Outcomes after Wavelight^® Topography-Guided CONTOURA^® Vision LASIK using Phorcides^

Patient-reported outcomes are critical to evaluating post-LASIK results. In this prospective, observational, investigator-initiated trial, subjects underwent bilateral TG LASIK with CONTOURA^® Vision, using the WaveLight^® FS200 femtosecond laser and EX500 excimer laser and using Phorcides^ for surgical planning. Outcomes were measured at 26 weeks (6.5 months) post-operatively. We assessed subjective outcomes using a modified PROWL questionnaire, which is validated for assessment of patient satisfaction after LASIK. We also analyzed visual acuity and higher-order aberrations. In total, 46 subjects completed the study.⁴

At 26 weeks post-operatively, the modified PROWL survey showed significant improvement on the Global Vision Satisfaction Index where a score of one represented “least satisfied” and a score of five represented “most satisfied”. The average uncorrected post-operative score of five was a significant improvement over the corrected baseline average of 4.1 on the five-point scale. In addition, 100% of subjects reported the maximum score of five for overall satisfaction with their vision. Analysis of individual questionnaire items also showed significant improvements versus baseline. Subjects showed improvements with respect to vision while driving at night, symptoms of glare, halos, and starbursts, symptoms of dry eye, and improvement on the global symptom assessment.⁴

Post operative uncorrected distance visual acuity was also excellent with more subjects reaching 20/16 or better compared to preoperative best corrected vision. Binocular uncorrected distance acuity was 20/10 or better for 15% of subjects, 20/12.5 or better for 87% of subjects and 20/16 or better for 100% of subjects. Additionally, eighty-three percent of subjects gained at least one line of Snellen binocular best-corrected distance visual acuity, while the rest had no change.⁴

This study also looked at the objective scatter index and total corneal higher-order aberrations at a four-millimeter optic zone. The results showed that there was no significant change from baseline to 6.5 months post-operatively.⁴

Conclusion

CONTOURA^® Vision, and specifically the use of the Phorcides^ software, provides excellent visual outcomes particularly at the 20/15 or better level.^2-5 The Phorcides^ software helps surgeons avoid the subjective nature of CONTOURA^® Vision that can require determining the right balance of cylinder magnitude and axis, and it provides a more objective, simplified approach that makes it more appealing to surgeons. This study, assessing patient reported outcomes, shows that CONTOURA^® Vision provides significant improvement in patient satisfaction after treatment.⁴ It was also key in demonstrating that CONTOURA^® Vision TG LASIK with Phorcides^, provides the benefit of improving visual quality beyond what can be measured objectively with visual acuity. The use of Phorcides^ allows for easy and reliable planning for CONTOURA^® Vision and shows exceptional satisfaction and visual outcomes that surgeons can be confident in.⁴

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