This article is part of Ophthalmology Advisor’s conference coverage from the 2021 meeting of The Association for Research in Vision and Ophthalmology (ARVO), held virtually from May 1 to 7, 2021. The team at Ophthalmology Advisor will be reporting on a variety of the research presented by the eye and vision experts at ARVO. Check back for more from the ARVO 2021 Meeting.

 

The reliability of wavefront (WF) astigmatism measurements appears to decrease as the severity of an individual patient’s keratoconus increases , according to research results presented at the Association for Research in Vision and Ophthalmology (ARVO) 2021 Annual Meeting, held May 1 to May 7, 2021.


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Researchers conducted a retrospective, observational clinical study to compare refractive results of manifest refraction and WV refraction through analyzing 613 eyes of patients diagnosed with keratoconus.

They compared refractive parameters of the eyes (sphere, cylinder, axis, and spherical equivalent) from stratified cohorts segmented into 4 groups based on increasing maximum keratometry (Kmax). Those groups included patients with Kmax lower than 50 D, 50 D to 55 D, 55 D to 60 D, and greater than 60 D). The researchers analyzed the portion of patients with WF axes ±10o of manifest axes, comparing them with the percentage of WF refraction areas (against-the-rule (ATR) (60˚ to 120o), with-the-rule (WTR) (0˚ to 30o and 150˚ to 180o), oblique (OBL) (30˚ to 60o and 120˚ to 150o) that accurately supported manifest refraction axes.

While the researchers found no difference between WF and manifest spherical refraction (P =.07), cylindrical refraction and spherical equivalent were significantly different (P <.001).

Cylindrical refraction measured on WF was larger than manifest refraction for all stratified Kmax subgroups (P <.001). In the Kmax 50D, 50 D to 55 D, and 55 to 60 D subgroups, WF spherical equivalent was more myopic than the manifest spherical equivalent (P =.01, P <.001, P <.001, respectively).

The majority (56.61%) of WF refraction axes supported manifest refraction axes. Only 34.4% of WF refraction axes were within 10o of manifest refraction axes. In the Kmax <50D, 50 D to 55 D, 55 D to 60 D, and >60 D subgroups, 62.1%, 54.7%, 56.7%, and 48.5% of WF refraction axes, respectively, correctly corroborated with manifest refraction axes, and 38.5%, 37.4%, 32.9%, and 18.2% of WF refraction axes were within 10o of the manifest refraction axes, respectively.

“WF refraction is a convenient tool for obtaining refractive parameters of patients, but physicians should be cognizant that there can be significant differences between WF and manifest refraction for patients with keratoconus,” the research shows.

Disclosure: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.  

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Reference

Greenstein S, Gelles J, Hersh P, et al. Manifest refraction versus wavefront refraction in patients with keratoconus: corneal biomechanics, keratoconus and collagen crosslinking. Poster session. Presented at: The Association for Research in Vision and Ophthalmology (ARVO) 2021 Annual Meeting; May 1-7; Virtual. Abstract 3531675.