Outer retinal layer thickness in patients with glaucoma with horizontal hemifield visual field defects

Abstract

Background/AimsTo determine the effect of glaucoma on outer retinal layer thickness in eyes with horizontal hemifield visual field (VF) defects.MethodsWe conducted a cross-sectional study in glaucomatous eyes with repeatable (in three or examinations) horizontal hemifield VF (programme 24–2) defect defined as: all five nasal VF locations immediately either above or below the horizontal midline abnormal in the pattern deviation plot with p<0.5%; no mirror-image adjacent 5 VF locations abnormal in the pattern deviation plot and no non-edge VF locations in the non-affected hemifield abnormal in the pattern deviation plot with p<1%. We used optical coherence tomography to measure thickness of each retinal layer in the temporal macula (12° horizontally and 24° vertically) and computed the absolute (µm) and relative (%) intraindividual asymmetry between the perimetrically normal and abnormal hemimacula.ResultsWe included 10 eyes of 8 patients with median age of 67 years and median VF mean deviation of −8.85 dB. The nerve fibre, ganglion cell and inner plexiform layers were significantly thinner in the perimetrically abnormal hemimacula (median asymmetry of –6.4, –11.5 and −3.8 µm, (corresponding to –27.7, –40.5 and −15.7 %), respectively, all p≤0.01). The inner nuclear layer was slightly thicker in the perimetrically abnormal hemimacula (median asymmetry of 1.3 µm (5.0 %), p=0.01). The outer plexiform, outer nuclear and photoreceptor layers asymmetry values were negligible.ConclusionOur study showed no evidence that glaucoma has an effect on the outer retinal layer thickness. In contrast, a large impact was observed in inner layer thickness.

Comparison of Rates of Progression of Macular OCT Measures in Glaucoma

“…This is consistent with conclusions of previous studies that ORLs are not affected by glaucoma and that ORL thickness decreases with age rather than disease severity. 16,17,29 Due to the relatively short-term follow-up, the overall magnitude of trends was small, and we did not expect to detect large changes in the central VF. The average worsening of MD on the 10-2 fields was about 1 dB in the entire group over the course of the follow-up.…”

“…FMT rates of change are partially driven by ORL change rates, which likely represent age-related decay. Although there is no evidence that the outer retina is affected in glaucoma, 16 age-related changes do occur in the outer retina, which could explain the faster FMT rates of change compared to GCC. 19,29 This is also supported by the fact that FMT and ORL showed the highest agreement on the UpSet plot (see Fig.…”

“…This is consistent with conclusions of previous studies that ORLs are not affected by glaucoma and that ORL thickness decreases with age rather than disease severity. 16 , 17 , 29 …”

“…The outer half of the retina beyond the inner plexiform layer (outer retinal layers [ORLs]) is not affected by glaucoma, and ORL measurements do not distinguish between healthy and diseased eyes or identify glaucomatous progression. [15][16][17][18] A crosssectional study estimated that the entire retina thinned out at a rate of −0.24 μm/year and that the outer nuclear layer had the fastest rate among the individual layers (−0.1 μm/year). 19 Although glaucoma leads to thinning of the inner retinal layers, ORL thinning is not expected to occur in glaucoma.…”

“…19 Although glaucoma leads to thinning of the inner retinal layers, ORL thinning is not expected to occur in glaucoma. [15][16][17][18] The goals of the current study are: (1) to compare the magnitude of rates of change at the level of superpixels and empirically defined macular sectors for four macular outcome measures consisting of FMT, GCC, GCIPL, and GCL thickness and compare those to ORL rates of change; (2) to define empirical macular sectors based on correlation of structural rates of change; (3) to estimate the influence of baseline glaucoma damage on the performance of the above measures to detect progression; and (4) to compare structural rates of progression in stable and progressing eyes according to central VFs.…”