Comparing the Rule of 5 to Trend-based Analysis for Detecting Glaucoma Progression on OCT.

Area of Science:

• Ophthalmology
• Medical Imaging
• Glaucoma Research

Background:

• The rule of 5 is a clinical standard for detecting retinal nerve fiber layer (RNFL) change on spectral-domain OCT (SD-OCT), defining significant change as a 5 μm global RNFL loss.
• This rule relies on short-term test-retest variability of SD-OCT and is widely adopted in clinical practice for monitoring glaucoma.

Purpose of the Study:

• To compare the efficacy of the rule of 5 against trend-based analysis for identifying glaucomatous progression.
• To evaluate the performance of trend-based analysis in detecting longitudinal changes in global RNFL thickness over time.

Main Methods:

• A prospective cohort study involving 300 eyes of 210 glaucoma subjects followed for an average of 5.4 years.
• Trend-based analysis utilized ordinary least-squares (OLS) linear regression of global RNFL thickness over time.
• Specificity was matched between trend-based analysis and the rule of 5 by assessing false-positives from randomly permuted follow-up visits.

Main Results:

• After 5 years, trend-based analysis identified significantly more progressing eyes (62.9%) than the rule of 5 (37.5%) at a matched specificity of 81.1%.
• Even when the rule of 5 required repeatable consecutive tests (93.4% specificity), its detection rate dropped to 21.0%, while trend-based analysis still showed a higher hit rate (47.4%).

Conclusions:

• Trend-based analysis demonstrates superior performance compared to the simple rule of 5 in detecting glaucoma progression.
• Trend-based analysis is recommended as a preferred method for the longitudinal assessment of global SD-OCT RNFL change in glaucoma patients.