Diagnostic Performance of the ISNT Rule for Glaucoma Based on the Heidelberg Retinal Tomograph

Abstract

Purpose: We determined the accuracy of the inferior . superior . nasal . temporal (ISNT) neuroretinal rim area rule and its variants in adult Asian populations, and evaluated whether disc area impacts its performance characteristics.Methods: Participants in the Singapore Malay Eye Study (SiMES) and Singapore Indian Eye Study (SINDI) underwent standardized ocular examinations, including optic disc imaging with the Heidelberg retinal tomograph (HRT). Glaucoma was defined using the ISGEO criteria. HRT rim areas in the superior, inferior, nasal, and temporal quadrants were quantified. We determined sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values of violating the ISNT rule and 4 variants (I . S . T, I . S, I . T, and combined I . T and S . T). The influence of disc area was analyzed with multivariate marginal logistic regression.Results: There were 6112 participants (mean age: 57.6 6 10.3 years). Glaucoma was present in 194 individuals (3.2%). Among 11,840 eyes, 232 (93.2%) of 249 glaucomatous eyes and 9768 (84.3%) of 11,591 nonglaucomatous eyes, violated the ISNT rule. The ISNT rule had highest sensitivity (93.5%), but lowest specificity (15.7%); I . T had highest specificity (98.2%), but low sensitivity (7.4%). For all variants, PPVs were low (2.1%-8.4%) and NPVs were high (97.9-99.1%). Larger disc area was associated with reduced specificity for the ISNT rule (P , 0.001), and reduced sensitivity (P ¼ 0.01) and increased specificity for I . S . T (P , 0.05). PPV increased (P , 0.05) and NPV decreased (P , 0.001) with increasing disc area. Conclusions:The ISNT rule based on HRT has high sensitivity, and the I . T, S . T, and combined I . T and S . T variants have high specificity. Disc area influences sensitivity, specificity, PPV, and NPV of the ISNT rule and its variants.Translational Relevance: The high sensitivity of the ISNT rule, and high specificities of its variants, may have potential utility when used in combination with other HRT algorithms for glaucoma assessment.

Reduced retinal nerve fibre layer thickness in children with severe obesity

“…Regarding eye examination, the overall distribution of the RNFL thickness measured by OCT and reflected by quadrants in relation to participant SDS‐BMI distribution is showed in Table . The thickest RNFL values were found in the inferior quadrant, followed by the superior, nasal and temporal retinal quadrants; therefore, they follow the inferior ≥ superior ≥ nasal ≥ temporal (ISNT) rule in normal, overweight and obese children with SDS‐BMI < 4 as it occurs in glaucoma . However, in severely obese children (SDS‐BMI > 4), the nasal quadrant was thinner than the temporal one.…”

Application of the ISNT rules on retinal nerve fibre layer thickness and neuroretinal rim area in healthy myopic eyes

“…In a population based study, Chan et al. () reported that only 15.7% of non‐glaucomatous eyes obeyed the ISNT rule on rim area obtained with HRT3. In another study, Nayak et al.…”

“…Moreover, disc area was reported to be associated with the performance of ISNT rule (Chan et al. ; Nayak et al. ).…”

Predicting Development of Glaucomatous Visual Field Conversion Using Baseline Fourier-Domain Optical Coherence Tomography

“…The PSD and GHT indices are more sensitive to focal VF defects that may correspond better to macular structural loss measured by GCC-FLV. Finally, focal loss that involves the macula may be a common pattern of glaucoma damage and reflective of the increased vulnerability of the inferotemporal disc 21,22 and inferior macula or superior visual field 23 respectively.…”