Relationship Between Photoreceptor Outer Segment Length and Visual Acuity in Diabetic Macular Edema

Abstract

Objective-To quantify photoreceptor outer segment (PROS) length in patients with diabetic macular edema (DME) using spectral domain optical coherence tomography (OCT), and to describe the correlation between PROS length and visual acuity in this group of patients. Design-Prospective study.Participants-Twenty-seven consecutive patients (30 eyes) with DME.Methods-Three SD-OCT scans were performed on all eyes during each session using Cirrus™ HD-OCT. A prototype algorithm was developed for quantitative assessment of PROS length. Retinal thicknesses and PROS lengths were calculated for three parameters; macular grid (6mm × 6mm), central subfield (1mm), and center foveal point (0.33mm). Intrasession repeatability was assessed using coefficient of variation (CV W ) and intraclass correlation coefficient (ICC). Association between retinal thickness and PROS length with visual acuity was assessed using linear regression and Pearson correlation analyses.Main Outcome Measure-Intrasession repeatability of macular parameters, and correlation of these parameters with visual acuity.Results-Mean retinal thickness and PROS length were 298-381 μm and 30-32 μm, respectively, for macular parameters assessed in this study. CV W values were 0.75-4.13% for retinal thickness, and 1.97-14.01% for PROS length. ICC values were 0.96-0.99 and 0.73-0.98 for retinal thickness and PROS length, respectively. Slopes from linear regression analyses assessing the association of retinal thickness and visual acuity were not significantly different from zero (p>0.20), whereas the slopes of PROS length and visual acuity were significantly different from zero (p<0.0005). Correlation coefficients for macular thickness and visual acuity ranged from 0.13 to 0.22, while coefficients for PROS length and visual acuity ranged from -0.61 to -0.81.Conclusions-PROS length can be quantitatively assessed using Cirrus™ HD-OCT. Although the intrasession repeatability of PROS measurements was less than that of macular thickness measurements, the stronger correlation of PROS length with visual acuity suggests that PROS

Association of outer retinal layer morphology with visual acuity in patients with retinal vein occlusion: SCORE Study Report 13

“…Thus, the results from this study using TD OCT are likely applicable to SD OCT. Recent literature has focused on outer segment length as an important predictor of VA. 8,9 We did not analyze outer segment length in this sample due to the lack of tools for the required minute measurements in the manufacturer's software. Photoreceptor length has also been found to be correlated with VA in macular oedema from RVO (r ¼ À 0.571) 14 but in our experience is difficult to define in eyes with macular oedema due to RVO.…”

“…[1][2][3][4][5] However, the correlation between OCT-measured central retinal thickness and visual acuity (VA) is only modest among a variety of retinal diseases. [6][7][8][9][10] Emerging literature suggests that both qualitative and quantitative features of the outer retina may correlate with VA in various macular pathologies, including retinal vein occlusion (RVO). 9,11,[12][13][14] If so, outer retinal morphology may be an important predictor of visual function and emerge as an important endpoint in clinical trials of RVO and other conditions.…”

Correlation between central subfield thickness, visual acuity and structural changes in diabetic macular edema

“…Blumenkranz et al concluded that many factors influence visual function in eyes with DME, including morphologic pattern of edema (cystic or diffuse retinal thickening), duration of retinal edema, retinal perfusion, total retinal volume, and vitreomacular interface abnor malities (posterior hyaloidal traction, epiretinal membrane, and serous or tractional retinal detachment (8) . Recent findings using Cirrus TM SD-OCT suggest a strong and reliable correlation of photoreceptor outer segment length with vi sual acuity (9) . Otani et al investigated the correlation of best-corrected visual acuity with foveal microstructural changes of the external limiting mem brane and the junction between the inner and outer segments (IS/OS) of the photoreceptors in DME.…”

“…It is not possible to know if the average photoreceptor outer segment length shortening observed in DME is caused by multiple points of localized breakdown of the IS/OS junction or from generalized thinning of the photoreceptor outer segment. The reasons can be explained based on what is known about the pathophysiology of this disease, such as tissue ischemia, lipid and fluid exudation and accumulation of toxic metabolic waste products and inflammatory mediators in DME (9) . The visual acuity not always is improved after treatments of the macular edema, which suggests that macular thickness is only one of the factors that worsen the visual function.…”

Spectral domain ocular coherence tomography findings pre- and post vitrectomy with fibrovascular membrane delamination for proliferative diabetic retinopathy

“…[11][12][13] Interestingly, reduced photoreceptor outer-segment thickness also correlates with poor visual function in DMO, indicating that outer retinal structural changes in the absence of traction may be observed in diabetic eyes. 14 In one recent study, the integrity of the IS/ OS and ELM bands were shown to correlate well with visual acuity following pars plana vitrectomy (PPV) for PDR. 15 The study included a significant number of eyes with non-clearing vitreous haemorrhage and pre-macular haemorrhage that may have contributed to worse mean visual acuity levels preoperatively and significantly improved mean levels of vision at last follow-up.…”