To evaluate the prevalence of nasal or temporal shifts in retinal nerve fiber layer (RNFL) peak contours with Stratus optical coherence tomography (OCT) and possible associations with demographic or glaucoma-related variables in glaucoma patients and glaucoma suspects, and to emphasize the importance of this finding in clinical practice.
This was a retrospective case series of glaucoma patients and glaucoma suspects (1 eye per patient) who underwent a Fast RNFL thickness study with the Stratus OCT. A study was considered to have a clinically significant horizontal deviation if there was greater than 20 degrees shift from the normative database in both superior and inferior peaks. A second cutoff value of 12 degrees was also used to examine smaller deviations. A linear regression model was used to assess correlations of demographic and glaucoma-related variables between eyes with and without significant deviations.
Of 400 subjects screened, 273 met the inclusion and exclusion criteria. Thirty-nine eyes (14.3%) had clinically significant horizontal deviation using the 20 degrees cutoff [95% confidence interval (CI), 10%-19%], whereas 122 (44.7%) met the definition with the 12 degrees cutoff (95% CI, 38%-51%). In addition, 121 eyes (44.3%) had a greater than 20 degrees horizontal shift of either the superior or inferior peak (95% CI, 38%-51%). There was no correlation with the demographic or glaucoma-related variables and the horizontal deviation of peak contours.
This study suggests that the significant horizontal deviation of peak RNFL contours with the Stratus OCT Fast RNFL is common and emphasizes the need for caution when interpreting the influence of such deviations on clock-hour segment thinning. It is not possible with this technology to distinguish between translational scan circle misalignment (horizontal or vertical) and anatomic variation as the explanation for the finding, and further study with newer technology is needed.
Yale School of Medicine, Department of Ophthalmology and Visual Sciences, New Haven, CT
Reprints: Milton Bruce Shields, MD, Yale School of Medicine, Department of Ophthalmology and Visual Sciences, 40 Temple Street, 3rd Floor, Suite 3D, New Haven, CT 06510 (e-mail: firstname.lastname@example.org).
Received for publication December 13, 2008; accepted March 28, 2009
Supported in part by Connecticut Lions Eye Research Foundation, Research to Prevent Blindness and Yale University School of Medicine Medical Student Research Fellowship. Pam Ossorio assisted with acquisition of OCT studies.