First-Year Variability of CRT Predictive of Long-Term Visual Outcomes in nAMD


The study data indicate high early-stage CRT variability showed a significantly higher risk of legal blindness.

New research reported that individuals with neovascular age-related macular degeneration (nAMD) and an early-stage variation in central retinal thickness (CRT) higher than 20% were more likely to experience legal blindness.

These findings add to existing literature and demonstrate a robust, significant association between early-stage variability of CRT and the risk of longer term visual outcomes, according to investigators from Fudan University.

“Our findings emphasize the importance of early assessment of disease,” wrote study author Zhenyu Wu, PhD, Department of Biostatistics, School of Public Health, Key Laboratory of Public Health Safety and Collaborative Innovation Center of Social Risks Governance in Health. “Patients with different early-stage variabilities have completely different risks of blindness, which would be helpful in long-term disease management.”

With the introduction of anti-vascular endothelial growth factor (anti-VEGF) agents into clinical practice, the incidence of AMD-related blindness has decreased by approximately 50% in developed countries. However, investigators noted that the generalization of treatment is subject to the personalized treatment effect, resulting in an unmet need to identify factors that allow the delivery of individualized management, such as CRT.

As the first year is key in monitoring disease progression after anti-VEGF initiation, the team defined it as the “early stage” and conducted the study to examine the relationship between variation of CRT and visual outcome during this stage. They hypothesized that a high first-year variability may lead to an increased risk of adverse long-term visual outcomes.

Investigators included 103 patients with nAMD who were 50 years and older, treatment-naive with complete baseline information, and received standard anti-VEGF treatment from a 10-year longitudinal cohort from the Moorfields Eye Hospital in the United Kingdom. Patients with less than one-year of follow-up data and those who experienced best-corrected visual acuity (BCVA) ≥35 were excluded from the study.

Following an initial loading phase of intravitreal ranibizumab injection for 3 consecutive months, inactive patients received a pro re nata (PRN) regimen with treatment as needed along with monthly visits. Or, patients were offered the treat-and-extend (T&E) regimen.

Early-stage variability in CRT was measured as the first-year coefficient of variability (CV) of CRT and patients were classified into high-variability and low-variability groups according to the X-tile. The time-to-event primary endpoint was the overall visual preservation (OVP) rate, defined as the time from the first injection to legal blindness (BCVA ≤35 ETDRS letters after one-year treatment).

Investigators included a total of 76 eyes from qualified patients and categorized them into the high- and low-variability groups. Thus, a threshold of 20% of first-year CV in CRT was used to categorize the patients into high-variability (n = 35, 46.1%) and low-variability (n = 41, 53.9%).

The study reported 43 patients experienced legal blindness during the study period and individuals with high variability had a significantly higher chance of becoming blind than those with low variability (70.7% vs. 40.0%; P <.05).

The research indicated that, as expected by investigators, patients with high-variability showed significantly worse OVP than those with low-variability (P = .002). Data show the 5- and 10-year OVP for patients with high- vs. low-variability were 76% vs. 48% and 59% vs. 22%, respectively.

Moreover, patients with high-variability remained at a significantly higher risk of adverse visual outcomes when demographic or clinical features were adjusted (hazard ratio [HR], 2.39; 95% CI, 1.20 to 4.78).

“Patients with high variability should be closely monitored, and more frequent injections should be considered,” Wu wrote. “Although the etiology of nAMD is complex and the pathological mechanism remains unclear, the findings of this study would be helpful for management of patients.”

The study, “The First-Year Variation in Central Retinal Thickness Predicts Legal Blindness in Patients with Neovascular Age-Related Macular Degeneration,” was published in Ophthalmic Research.

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