Inferior Nasal Step and Enlarged Blind Spot Most Common Early VF Changes in Glaucoma

In a study of 1,330 eyes, researchers applied an automated, rule-based system to classify visual field defects using OHTS criteria. Inferior nasal step (22.6%) and inferior enlarged blind spot (19.1%) were the most common repeatable patterns. This objective method, they say, may reduce variability in glaucoma assessment and improve consistency in detecting early disease progression. These images from the study show locations of involvement of bundle (top) and non-bundle (bottom) visual field defects on the 24-2 grid, using a right eye configuration. Photo: Tan JCK, et al. Ophthalmology Glaucoma. September 25, 2025. Click image to enlarge. Visual field (VF) function using standard automated perimetry (SAP) remains essential for diagnosing and monitoring patients with suspected or manifest glaucoma. Yet, existing VF grading systems are complex, impractical and prone to subjective interpretation, leading to interobserver disagreement. The creation of a new objective, quantitative method for classifying VF defects could reasonably improve accuracy, consistency and ease of use, according to a group of researchers from Australia who sought to test this theory. Using the Ocular Hypertension Treatment Study (OHTS) visual field classification system, they identified the most commonly seen defects, the results of which were recently published in Ophthalmology Glaucoma. This study included a total of 1,330 eyes of 733 patients, with a mean age of 64.2. Of these, 444 eyes (33.4%) had a diagnosis of glaucoma, 753 eyes (56.6%) were glaucoma suspects and the remaining 133 (10%) eyes were healthy. The mean baseline mean deviation (MD) and pattern standard deviation (PSD) was -1.08 and 2.26 respectively. The most common repeatable pattern was the inferior nasal step (22.6%), followed by the inferior enlarged blind spot (19.1%), superior nasal step (12.6%) and superior enlarged blind spot (11.6%), according to the results. The frequency of occurrence of initial defects was significantly higher than repeatable defects for the majority of patterns. The largest difference was observed for the superior enlarged blind spot (32.9% vs. 11.6%, inferior blind spot (38.9% vs. 19.1%, inferior vertical step (20.7% vs. 7.7%) and inferior depression (19.6% vs. 6.8%). There was no significant difference between initial and repeatable defects for the nasal and temporal hemifields, superior altitudinal, superotemporal quadrant and partial peripheral rim defects.The authors explained their method of quantifying VF defects was developed by “translating descriptions of defects in the OHTS system into code logic for automated analysis.” They explained that this approach integrates a quantitative, rule-based framework with clinician-informed definitions of defect types, preserving interpretability and aligning more closely with how clinicians conceptualize and describe these in practice. “Our system therefore classified defects into 14 patterns, which comprised five bundle and nine non-bundle patterns of defects,” they wrote in their paper. “Certain patterns included subclassifications, such as arcuate (full or partial), quadrant (superonasal, superotemporal, inferonasal and inferotemporal (which were further divided into full or partial), hemianopia (full or partial) and peripheral rim (full or partial).”Regarding defects in suspected and early glaucoma, the study found the most common type of bundle defects were nasal step, followed by arcuate and temporal wedge defects. Among the non-bundle defects, the most common were enlarged blind spot, followed by peripheral (superior/inferior) depression and vertical step and central defects. “It is therefore possible that some defects classified as enlarged blind spot, particularly in highly myopic eyes, may reflect refractive scotomas due to tilted optic discs rather than true glaucomatous damage,” the researchers wrote. The researchers say, because they used the custom quantitative criteria developed for the OHTS system, this could be a potential limitation, as the original system “does not explicitly specify the degree of involvement that constitutes a defect.” They wrote, “Consensus guidelines may be required to standardize the exact criteria used in the classification of locations and degree of involvement.” Additionally, their use of SITA-Faster may display different sensitivity and reliability outcomes compared to SITA-Fast and SITA-Standard, the authors noted, which may warrant further investigation. The authors suggest further studies should be conducted to explore the distribution of VF defects in more advanced disease in order to understand how these defect patterns evolve with progression.In conclusion, this study provides a method for applying objective criteria that could improve the accuracy and consistency of classifying VF defects that have historically been variable in suspected or early disease.Click here for the journal source. Tan JCK, Phu J. Quantitative classification of visual field defects in early glaucoma. Ophthalmology Glaucoma. September 25, 2025. [Epub ahead of print]. This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.