The Diagnostic Ability of Ganglion Cell Complex Thickness-to-Total Retinal Thickness Ratio in Glaucoma in a Caucasian Population

Abstract

Introduction Glaucoma is a progressive optic neuropathy characterized by retinal ganglion cell loss and thinning of the retinal nerve fiber layer (RNFL). 1,2 Glaucomatous visual field defects emerge after 30% of the retinal ganglion cells are lost. Therefore, structural tests are important in the early diagnosis and follow-up of glaucoma. 3 Previous optical coherence tomography (OCT) studies demonstrated peripapillary RNFL thinning in early Objectives: To evaluate the diagnostic accuracy of the macular ganglion cell complex-to-total retinal thickness (G/T) ratio in a Caucasian population. Materials and Methods: A total of 86 patients were enrolled in this cross-sectional study. Patients were divided into 4 groups: healthy; ocular hypertension; preperimetric glaucoma; and early glaucoma. Macular ganglion cell complex (mGCC) thickness, total retinal thickness, and retinal nerve fiber layer thickness (RNFLT) in one randomly selected eye of each patient were measured with measured with Heidelberg HD spectral domain optical coherence tomography (Heidelberg Engineering, Inc., Heidelberg, Germany). G/T ratio (%) was calculated as (mGCC thickness / total retinal thickness) x100. The ability of each parameter to diagnose glaucoma was examined by area under the receiver operating characteristic curve (AUROC) analysis and sensitivity evaluation at a fixed level of specificity. Unpaired t test was used to compare the measured values between the healthy subjects and the different patient groups. Results: The study included 9 healthy individuals, 18 patients with ocular hypertension, 28 with preperimetric glaucoma, and 31 with early glaucoma. Total retinal thickness, mGCC thickness, RNFLT, and G/T ratio were highest in the healthy group and decreased progressively in patients with ocular hypertension, preperimetric glaucoma, and early glaucoma. All comparisons between the groups were significant for these parameters (p<0.001 for all). Average RNFLT, average GCC, and total retinal thickness showed consistently higher AUROC than G/T ratio in the differentiation between healthy individuals and patients with ocular hypertension, preperimetric glaucoma, and early glaucoma. Conclusion: G/T ratio does not contribute to separation of ocular hypertension, preperimetric glaucoma, and early glaucoma patients from the healthy population. Compared to the other parameters investigated, G/T had lower diagnostic value.

Optical Coherence Tomography Evaluation of Peripapillary and Macular Structure Changes in Pre-perimetric Glaucoma, Early Perimetric Glaucoma, and Ocular Hypertension: A Systematic Review and Meta-Analysis

“…Our results demonstrated that the average and sectoral pRNFL, mGCIPL, and mGCC were significantly thinner in the EG eyes than in the PPG eyes. These findings were consistent across several studies ( 26 , 29 , 34 , 38 – 41 , 43 , 44 ), whereas the results of eight studies were not significantly different in terms of the average or sectoral pRNFL thickness ( 27 , 28 , 30 , 31 , 35 – 37 , 42 ); two studies reported there was no significant difference in the EG eyes compared to the PPG eyes concerning mGCC thickness ( 28 , 36 ), and one study did not demonstrate a significant reduction in the EG eyes regarding the average and superior mGCIPL thickness ( 33 ). Currently, the exact biomechanisms of glaucomatous neurodegeneration remain poorly understood ( 1 , 55 ).…”

“…The pooled results revealed that the pRNFL and mGCC were significantly thinner in the PPG eyes than those in the OHT eyes, which were consistent with several investigations ( 45 , 47 , 48 ). However, two studies reported that there was no difference in patients with PPG and OHT in terms of the average mGCC thickness ( 39 , 43 ); one study demonstrated that the average pRNFL thickness could not serve as a valued indicator for differential diagnosis ( 43 ), and another study showed that no difference was noted in the PPG eyes and OHT eyes regarding the superior mGCC thickness ( 46 ).…”

“…Several studies using OCT have reported that the attenuation of the peripapillary retinal nerve fiber layer (pRNFL), macular ganglion cell plus inner plexiform layer (GCIPL), and macular ganglion cell complex (mGCC) could be hallmark features of glaucoma ( 20 , 22 , 24 , 25 ). Although some investigations have revealed the continuum of glaucoma from mild to advanced stages, studies have shown inconsistencies regarding the diagnostic values of OCT indicators in differentiating PPG from EG ( 26 – 44 ) and in differentiating PPG from OHT ( 39 , 43 , 45 – 48 ).…”

Screening for Glaucoma in Adults

“…Across all key questions, 83 studies (reported in 96 publications, total 75 887 participants) were included (30 trials and 53 diagnostic accuracy studies) (Figure 2). Sixteen studies were carried forward from the 2013 reviews, and 67 studies were new.…”

“…Fifty-three studies evaluated the diagnostic accuracy of screening tests (reported in 59 publications, n = 65 464) (eTables 3-4 in the Supplement). Most studies evaluated spectral-domain OCT (29 studies, n = 11 434), tonometry (17 studies, n = 49 742), and visual field assessment (10 studies, n = 11 633). No study evaluated the diagnostic accuracy of a comprehensive ophthalmological examination.…”