Parapapillary Atrophy, Disc Tilt May Evolve With High Myopia in Young Eyes

Physicians should monitor characteristics such as parapapillary atrophy (PPA) area, disc tilt, disc area, axial length (AL), and spherical equivalent refraction (SER), when managing patients with high myopia, according to a report published in BMC Ophthalmology. A study shows that microstructural changes can be observed even in adolescence. 

The cross-sectional analysis included 112 individuals with high myopia (mean age, 19.23±4.69 years; range, 12-30 years). Participants’ average AL was 26.86±0.94 mm and average SER of -8.26±1.41 diopters (D). All participants were evaluated via tonometry, fundus photographs, optical low-coherence reflectometry (which was used to measure AL, central corneal thickness [CCT)], lens thickness [LT], and anterior chamber depth [ACD]), and optical coherence tomography angiography (OCT-A). Patients findings were analyzed via a multivariate regression analysis of the PPA area, degree of optic disc tilt, and disc area.

Researchers found that optic disc area, disc tilt, and PPA area increased with greater AL. In adolescents — younger than 17 years of age — AL and SER were associated with degree of optic disc tilt; although in young adults, the 2 factors were connected to disc area rather than tilt. Overall, PPA area positively correlated with age (r =.22, P =.02).

“It could be speculated that optic disc tilt may occur under the mechanism of scleral stretching by axial elongation during myopia progression among highly myopic people,” according to the researchers. “It is novel that we observed the optic disc tilt were more associated with the AL and SER in the adolescent group, which might be the reason that the change in AL and SER was stronger in this age group.”

Further, PPA area correlated to both AL (r=.295, P =.002) and peripapillary retinal nerve fiber layer (pRNFL) thickness (r=.417, P <.001), although PPA negatively correlated with SER (r=-0.275, P =.003).

In the multivariate model, 2 structural features were independently associated with the area of PPA; optic disc tilt (P =.003), and disc area (P <.001). Two factors independently predicted the amount of optic disc tilt; AL (P =.010) and PPA area (P =.019) — while three elements anticipated disc area; PPA extent (P <.001), lens thickness (P =.009), and pRNFL thickness (P <.001).

Previous studies have shown that for those with high or other myopias, the degree of optic disc tilt, or anterior scleral angle around the disc may be related to changes which increase with age, and may also include Bruch membrane anterior surface tilt rate. In the current analysis, optic disc tilt was associated with disc area, pRNFL thickness, and AL, along with ovality index. Also, investigators discovered the amount of optic disc tilt was related to increase in myopic SER among adolescent participants, but with longer AL in young adult patients. 

Other studies demonstrated a relationship between greater myopia and a larger optic disc. Present data similarly reveals disc area was associated with factors such as AL (r=.221, P =.019), but not SER (r=-0.158, P =.096). Disc area was also associated with pRNFL thickness, radial peripapillary capillary vessel density, and lens thickness.

Limitations of this analysis comprised a lack of classification based on severity of refractive error or by axial length. Also, the design did not include a group of eyes with 20/20 emmetropic vision. Although, extensive examinations featured a wide range of testing, such as OCT-A and optical low-coherence reflectometry.