EC Ophthalmology

With so many advances in devices that can measure the corneal shape, the treatment of astigmatism can be further refined to improve visual outcomes with refractive laser surgery.

The ability to accurately measure both the front and back of the cornea together with the astigmatism at different zones of the cornea allows for perfecting current treatments of astigmatism.

The method of vector planning which incorporates both the corneal as well as the refractive parameters in the treatment plan has been well documented in its superior astigmatic outcomes compared to treatments planned using refractive parameters alone [1-4]. By calculating the ocular residual astigmatism (ORA) [5] routinely preoperatively the surgeon is able to establish how much astigmatism can be corrected at the time of laser eye surgery and advise the patient accordingly.

Vector planning places emphasis on the ORA to distribute this untreatable amount of astigmatism to both the cornea and manifest refraction postoperatively while at the same time targeting a spherical equivalent of zero. The benefits shown by the vector planning studies are a significant reduction in postoperative corneal astigmatism as well as refractive cylinder compared to treatment paradigms based on refractive parameters alone [1-4].

1. Alpins NA and Stamatelatos G. “Customized photoastigmatic refractive keratectomy using combined topographic and refractive data for myopia and astigmatism in eyes with forme fruste and mild keratoconus”. Journal of Cataract and Refractive Surgery 33 (2007): 591-602.
2. Alpins NA and Stamatelatos G. “Clinical Outcomes for laser in situ keratomileusis using combined topography and refractive wavefront treatments for myopic astigmatism”. Journal of Cataract and Refractive Surgery 34 (2008): 1250-1259.
3. Arbelaez MC., et al. “Clinical outcomes of laser in situ keratomileusis with an aberration-neutral profile centered on the corneal vertex comparing vector planning with manifest refraction planning for the treatment of myopic astigmatism”. Journal of Cataract and Refractive Surgery 43 (2017): 1504-1514.
4. Jun I., et al. “Comparison of clinical outcomes between vector planning and manifest refraction planning in SMILE for myopic astigmatism”. Journal of Cataract and Refractive Surgery8 (2020): 1149-1158.
5. Alpins NA. “New method of targeting vectors to treat astigmatism”. Journal of Cataract and Refractive Surgery 23 (1997): 65-75.
6. Alpins NA and Stamatelatos G. “New method of quantifying corneal topographic astigmatism that corresponds with manifest refractive cylinder”. Journal of Cataract and Refractive Surgery 38 (2012): 1978-1988.
7. Alpins NA., et al. “Corneal Topographic Astigmatism (CorT) to Quantify Total Corneal Astigmatism”. Journal of Refractive Surgery3 (2015): 182-186.
8. Hemidivisional Vector Planning to Reduce and Regularize Irregular Astigmatism by Laser Treatment. Graefe’s Archive for Clinical and Experimental Ophthalmology (2022).