Detection of Progressive Retinal Nerve Fiber Layer Loss in Glaucoma Using Scanning Laser Polarimetry with Variable Corneal Compensation

Abstract

Purpose To evaluate the ability of scanning laser polarimetry with variable corneal compensation to detect progressive retinal nerve fiber layer (RNFL) loss in glaucoma patients and patients suspected of having the disease. Methods This was an observational cohort study that included 335 eyes of 195 patients. Images were obtained annually with the GDx VCC scanning laser polarimeter, along with optic disc stereophotographs and standard automated perimetry (SAP) visual fields. The median follow-up time was 3.94 years. Progression was determined using commercial software for SAP and by masked assessment of optic disc stereophotographs performed by expert graders. Random coefficient models were used to evaluate the relationship between RNFL thickness measurements over time and progression as determined by SAP and/or stereophotographs. Results From the 335 eyes, 34 (10%) showed progression over time by stereophotographs and/or SAP. Average GDx VCC measurements decreased significantly over time for both progressors as well as non-progressors. However, the rate of decline was significantly higher in the progressing group (−0.70 μm/year) compared to the non-progressing group (−0.14 μm/year; P = 0.001). Black race and male sex were significantly associated with higher rates of RNFL loss during follow-up. Conclusions The GDx VCC scanning laser polarimeter was able to identify longitudinal RNFL loss in eyes that showed progression in optic disc stereophotographs and/or visual fields. These findings suggest that this technology could be useful to detect and monitor progressive disease in patients with established diagnosis of glaucoma or suspected of having the disease.

Rates of retinal nerve fibre layer thickness change in glaucoma patients and control subjects

“…30,31 Previous studies have reported mean rates from VCC, ECC, and OCT to be significantly more negative in progressing compared with non-progressing glaucoma patients. [15][16][17][18]32,33 In these studies, progression was determined by visual field changes and/or expertassessed stereophotograph changes. However, this previous research is not directly comparable to the present study because glaucoma patients were not segregated into progressing or non-progressing categories.…”

“…The latter explanation is plausible for these patients as their median RNFLT at baseline was 43, 39 and 69 mm for VCC, ECC and OCT, respectively, values lower than previously reported. [15][16][17][18]32,33 Despite this, these patients would be considered to have early to moderate glaucomatous damage by their visual field state (median MD: À 3.6 dB) where changes are often considered to be more easily detected. Evidence is also emerging that in experimental glaucoma, changes in RNFL retardance 40,41 and reflectance 42 can precede changes in RNFLT, and this may explain a slower rate of SLP-measured RNFLT change in these patients.…”

“…Previous longitudinal studies have shown that VCC, ECC, and OCT can provide good discrimination in rates of RNFLT change between progressing and non-progressing glaucoma patients determined by visual field changes and/or expertassessed stereophotograph change. [15][16][17][18] This was a longitudinal, prospective, observational study, the aims of which were to describe RNFLT changes over time in a cohort of glaucoma patients and agesimilar control subjects measured by VCC, ECC, and OCT. Rates of change in SAP mean deviation (MD) were also estimated and used to assess the differences in functional changes between glaucoma patients and control subjects.…”

Assessment of rates of structural change in glaucoma using imaging technologies

“…8 Results from these imaging technologies can be used to predict glaucoma development, [9][10][11][12][13] and have the potential to detect and measure structural progression. 7,[14][15][16][17][18][19][20][21][22][23][24] Recent literature has focused on the ability of these instruments to provide estimates of rates of change over time. In this review, we discuss the evidence with regard to the ability of current imaging technologies in measuring rates of structural change in glaucoma and their relationship to conventional methods for assessment of disease progression.…”

Evaluation of the Retinal Nerve Fiber Layer Thickness, the Mean Deviation, and the Visual Field Index in Progressive Glaucoma

“…3 Finally, agreement in the progression assessment among different functional and structural tests is only low. [6][7][8] During the last decade, progression detection algorithms have been implemented into imaging devices. Glaucoma progression analysis (GPA) software for optical coherence tomography (OCT) allows the identification and the quantification of changes in the retinal nerve fiber layer (RNFL) and optic nerve head over time and could be a useful tool to assess progression.…”