This article is more than 5 years old. Information may no longer be current.
SD-OCT parameters repeatable in high myopia
Researchers found spectral domain OCT parameters to be repeatable in subjects with high myopia when compared to those with emmetropia, according to a study in the Journal of Glaucoma.
The prospective, cross-sectional study included 93 eyes of 63 highly myopic subjects and 28 eyes of 14 emmetropic students chosen as a control group.
Highly myopic subjects had significantly smaller optic discs and rim measurements on spectral domain OCT (SD-OCT) compared with the emmetropes, Rao and colleagues reported.
Within the high myopia group, axial length had a significant positive association with disc measurement; disc area measurement increased as axial length increased.
Axial length significantly affected the repeatability of most of the retinal nerve fiber layer (RNFL) parameters but did not affect the repeatability of either the optic nerve head or the ganglion cell complex (GCC) parameters, according to researchers. Furthermore, axial length was positively associated with disc area and negatively associated with most RNFL parameters.
The researchers reported that all RNFL parameters, except temporal quadrant RNFL thickness, were thinner in high myopic subjects.
In the repeatability analysis, all GCC parameters were comparable between the highly myopic and emmetropic subjects.
The study results suggest that SD-OCT can be useful for following up glaucoma patients with high myopia to detect progression, according to researchers. – by Abigail Sutton
Disclosure: Rao is a consultant for both Allergan and Cipla. The remaining researchers reported no relevant financial disclosures.
Perspective
Back to Top
Myopia is both a risk factor and confounding variable in the diagnosis and monitoring of open-angle glaucoma. Given its increasing global prevalence, anything that informs the management of glaucoma in nearsighted individuals is a welcome addition to our toolbox.
The increased axial length, magnification artifacts, retinal nerve fiber layer bundle thinning and shifting, and atypical optic nerve head anatomy that accompany high myopia can make comparison to reference databases of questionable value in establishing a diagnosis. However, detecting disease progression (the hallmark of glaucoma) hinges on minimal inter-test variability, and in demonstrating the repeatability of most OCT parameters in highly myopic eyes, Rao and colleagues confirm the value of longitudinal event- and trend-based analyses of structure, regardless of refractive status.
The authors also note that macular scans have superior inter-test consistency, complementing their diagnostic value in myopic eyes and emphasizing the importance of acquiring reliable baseline and follow-up data across as many structural and functional parameters as possible. A number of dynamic processes (ocular anatomy, disease stage and concurrent pathology, among others) determine which parameter is best suited to monitor for progression at any particular moment in time.
For that reason, glaucoma management is a bit like collecting Easter treats: it’s best not to put all your eggs in one basket.