A New Scan May Detect Glaucoma Progression Years Before It Shows Up on a Visual Field Test

This audio article is from VisualFieldTest.com.Read the full article here: https://visualfieldtest.com/en/a-new-scan-may-detect-glaucoma-progression-years-before-it-shows-up-on-a-visual-field-testTest your visual field online: https://visualfieldtest.comSupport the show so new episodes keep coming: https://www.buzzsprout.com/2563091/supportExcerpt:A New Scan May Detect Glaucoma Progression Years Before It Shows Up on a Visual Field Test Introduction A study published online on September 3, 2026, reported that optical coherence tomography angiography, or OCTA, detected event-based glaucoma progression an average of 2.3 years before visual-field progression. Conventional structural optical coherence tomography, or OCT, detected progression about 1.5 years before visual-field progression. JAMA Ophthalmology study () That sounds like a major breakthrough. It could imply that clinicians might identify worsening glaucoma long before patients lose measurable vision. However, the result needs careful interpretation. The study did not prove that OCTA detects the biological beginning of glaucoma damage two years earlier. It showed that an OCTA measurement crossed a predefined statistical threshold before a visual-field algorithm crossed its own threshold. Those are not necessarily the same thing. The most defensible conclusion is: > OCTA may provide an earlier vascular signal of progression in some eyes, but the evidence does not yet show that it reliably outperforms the best structural OCT strategy or that every OCTA alert represents irreversible retinal ganglion-cell loss. The New Study: What It Actually Found Study design and participants The study used patients from the Diagnostic Innovations in Glaucoma Study, a longitudinal research cohort. It included: 116 patients 180 eyes 111 eyes with perimetric glaucoma, meaning repeatable visual-field damage was already present 69 preperimetric eyes, meaning glaucomatous optic-nerve or structural damage was present without repeatable visual-field loss Mean age: 67.6 years Mean follow-up: 5.1 ± 1.4 years Minimum eligibility: at least 2 years of follow-up and at least four visits with each testing method The public abstract does not provide a detailed breakdown into mild, moderate, and advanced glaucoma. Therefore, it is not possible to know from the published abstract whether the two-year lead time was concentrated in early disease, moderate disease, advanced disease, or spread evenly across stages. JAMA Ophthalmology study () What was measured? The study compared: OCTA vessel-density change Circumpapillary retinal nerve fiber layer thickness change, measured by structural OCT Visual-field progression The abstract states that OCT and OCTA progression were defined as a change exceeding test-retest variability at two consecutive visits. Visual-field progression was assessed using the instrument’s Guided Progression Analysis. Important details are not available in the public abstract: The exact OCTA device The scan size Whether the main metric was peripapillary vessel density, optic-nerve-head vessel density, macular vessel density, or a combined measure The exact retinal slab The numerical test-retest thresholds Whether visual-field progression meant “possible” or “likely” Guided Progression Analysis progression Whether the structural OCT algorithm used only event analysis or also a slope-based trend analysis These missing details matter because OCTA vessel-density values are highly dependent on the device, scan size, software version, segmentation method, signal strength, and region measured. A related 2024 study from the same research group used an Optovue Avanti AngioVue system, with a 4.5-by-4.5-millimeter optic-nerve-head scan and a peripapillary annulus. But that study should not automatically be assumed to have used the identical protocol. Related event-based OCT/OCTA study () Progression detection During follow-up: For the full table, please open this article on visualfieldtest.com. Among the 107 eyes classified as progressing by at least one method: OCTA was the earliest detector in 40 eyes, or 37.4% Circumpapillary retinal nerve fiber layer OCT was earliest in 32 eyes, or 29.9% Visual-field testing was earliest in 26 eyes, or 24.3% These figures do not mean that OCTA was correct in 37.4% of all patients. They mean that among eyes in which at least one test detected progression, OCTA was the first test to cross that study’s threshold in about one-third of cases. Specificity and false-positive rates Among 45 eyes considered stable, reported specificity was: OCTA: 68.9% Circumpapillary retinal nerve fiber layer OCT: 75.6% That corresponds to approximate false-positive rates of: OCTA: 31.1%, or about 14 of the 45 stable eyes Circumpapillary retinal nerve fiber layer OCT: 24.4%, or about 11 of the 45 stable eyes This is an important limitation. The OCTA signal appeared earlier, but it was also less specific than the structural OCT measurement. The study did not report a conventional sensitivity against an independent gold standard because there is no perfect gold standard for slow glaucoma progression. Visual fields cannot serve as a completely independent reference when the question is whether OCTA detects change before visual fields. The number 58 of 107 progressing eyes, or approximately 54%, is a detection proportion, not a true sensitivity. Exact lead time The reported mean lead times were: OCTA before visual-field progression: 2.3 years 95% confidence interval: 1.3 to 3.2 years Circumpapillary retinal nerve fiber layer OCT before visual-field progression: 1.5 years 95% confidence interval: 0.6 to 2.4 years OCTA versus structural OCT: 0.2 years 95% confidence interval: −0.6 to 0.9 years That last comparison is crucial. The study did not show a clear two-year advantage over structural OCT. The difference between OCTA and retinal nerve fiber layer OCT was only 0.2 years, and the confidence interval included no difference and even favored structural OCT slightly. Therefore: > The strongest finding was that OCTA crossed its progression threshold earlier than visual fields. The evidence that OCTA is meaningfully earlier than structural OCT is weak. Why the Two-Year Advantage Should Not Be Accepted at Face Value It is a comparison of thresholds, not necessarily disease onset Visual-field progression is difficult to detect because visual-field testing is noisy. A test may need several abnormal results before the Guided Progression Analysis labels progression. OCTA may therefore appear to lead visual fields for two reasons: OCTA detected genuine earlier biological change. The visual field required more time and more repeated tests to overcome measurement noise. The study cannot fully distinguish these possibilities. The definition of progression was not identical across tests OCTA and OCT were considered positive when a measurement exceeded test-retest variability on two consecutive visits. Visual fields used Guided Progression Analysis. These algorithms ask different questions: OCTA asks whether a quantitative imaging measurement fell beyond an expected repeatability boundary. Structural OCT asks whether tissue thickness changed beyond its own boundary. Visual-field analysis asks whether sensitivity at selected points worsened beyond expected variability. A test with a lower threshold or greater biological responsiveness will tend to be classified as “earlier,” even if it is not more accurate. The study was retrospective and based on a referral cohort The Diagnostic Innovations in Glaucoma Study is valuable, but it is not a random sample of the general glaucoma population. Referral-center cohorts often contain: More atypical cases More established glaucoma More patients with suspicious or borderline findings More frequent imaging than ordinary clinical practice The results may not apply equally to patients with mild glaucoma, ocular hypertension, high myopia, cataract, diabetes, or poor-quality scans. The stable group was small The specificity estimate was based on only 45 stable eyes. A small change in the number of apparent false positives could substantially change the reported specificity. “Earlier” did not necessarily mean “actionable” An OCTA measurement might decline two years before the field crosses a statistical threshold, but the clinician still needs to know: Is the decline repeatable? Is it topographically consistent with the retinal nerve fiber layer or ganglion-cell layer? Is it still present after signal-strength correction? Could it reflect blood pressure, intraocular pressure, medication, or cataract changes? Does it predict future visual disability? The study did not establish that an OCTA alert should automatically lead to treatment escalation. Could the Early OCTA Signal Be an Artifact? Yes. Several explanations are biologically plausible. Visual-field noise Standard automated perimetry varies because of: Attention Fatigue Learning effects False-positive responses False-negative responses Fixation instability Dry eye and blinking Anxiety Advanced damage at the tested location The variability is often greater at already damaged locations. Guided Progression Analysis is designed to reduce false alarms, but false positives still occur. In one analysis of stable visual fields, the five-year cumulative false-positive rate was approximately 34% for “possible progression” and 7% for “likely progression.” Global mean-deviation and visual-field-index trend criteria had lower five-year false-positive rates of approximately 4% to 5%. Visual-field progression analSupport the show