Three-Dimensional Adaptive Optics–Assisted Visualization of Photoreceptors in Healthy and Pathologically Aged Eyes

Subretinal fibrosis secondary to neovascular age-related macular degeneration: mechanisms and potential therapeutic targets

Subretinal fibrosis is the end-stage sequelae of neovascular age-related macular degeneration. It causes local damage to photoreceptors, retinal pigment epithelium, and choroidal vessels, which leads to permanent central vision loss of patients with neovascular age-related macular degeneration. The pathogenesis of subretinal fibrosis is complex, and the underlying mechanisms are largely unknown. Therefore, there are no effective treatment options. A thorough understanding of the pathogenesis of subretinal fibrosis and its related mechanisms is important to elucidate its complications and explore potential treatments. The current article reviews several aspects of subretinal fibrosis, including the current understanding on the relationship between neovascular age-related macular degeneration and subretinal fibrosis; multimodal imaging techniques for subretinal fibrosis; animal models for studying subretinal fibrosis; cellular and non-cellular constituents of subretinal fibrosis; pathophysiological mechanisms involved in subretinal fibrosis, such as aging, infiltration of macrophages, different sources of mesenchymal transition to myofibroblast, and activation of complement system and immune cells; and several key molecules and signaling pathways participating in the pathogenesis of subretinal fibrosis, such as vascular endothelial growth factor, connective tissue growth factor, fibroblast growth factor 2, platelet-derived growth factor and platelet-derived growth factor receptor-β, transforming growth factor-β signaling pathway, Wnt signaling pathway, and the axis of heat shock protein 70-Toll-like receptors 2/4-interleukin-10. This review will improve the understanding of the pathogenesis of subretinal fibrosis, allow the discovery of molecular targets, and explore potential treatments for the management of subretinal fibrosis.

Sequence of Morphological Changes Preceding Atrophy in Intermediate AMD Using Deep Learning

Purpose

Investigating the sequence of morphological changes preceding outer plexiform layer (OPL) subsidence, a marker preceding geographic atrophy, in intermediate AMD (iAMD) using high-precision artificial intelligence (AI) quantifications on optical coherence tomography imaging.

Methods

In this longitudinal observational study, individuals with bilateral iAMD participating in a multicenter clinical trial were screened for OPL subsidence and RPE and outer retinal atrophy. OPL subsidence was segmented on an A-scan basis in optical coherence tomography volumes, obtained 6-monthly with 36 months follow-up. AI-based quantification of photoreceptor (PR) and outer nuclear layer (ONL) thickness, drusen height and choroidal hypertransmission (HT) was performed. Changes were compared between topographic areas of OPL subsidence (AS), drusen (AD), and reference (AR).

Results

Of 280 eyes of 140 individuals, OPL subsidence occurred in 53 eyes from 43 individuals. Thirty-six eyes developed RPE and outer retinal atrophy subsequently. In the cohort of 53 eyes showing OPL subsidence, PR and ONL thicknesses were significantly decreased in AS compared with AD and AR 12 and 18 months before OPL subsidence occurred, respectively (PR: 20 µm vs. 23 µm and 27 µm [P < 0.009]; ONL, 84 µm vs. 94 µm and 98 µm [P < 0.008]). Accelerated thinning of PR (0.6 µm/month; P < 0.001) and ONL (0.8 µm/month; P < 0.001) was observed in AS compared with AD and AR. Concomitant drusen regression and hypertransmission increase at the occurrence of OPL subsidence underline the atrophic progress in areas affected by OPL subsidence.

Conclusions

PR and ONL thinning are early subclinical features associated with subsequent OPL subsidence, an indicator of progression toward geographic atrophy. AI algorithms are able to predict and quantify morphological precursors of iAMD conversion and allow personalized risk stratification.

Reticular Pseudodrusen Are Associated With More Advanced Para-Central Photoreceptor Degeneration in Intermediate Age-Related Macular Degeneration

Purpose

The purpose of this study was to examine retinal topographical differences between intermediate age-related macular degeneration (iAMD) with reticular pseudodrusen (RPD) versus iAMD without RPD, using high-density optical coherence tomography (OCT) cluster analysis.

Methods

Single eyes from 153 individuals (51 with iAMD+RPD, 51 with iAMD, and 51 healthy) were propensity-score matched by age, sex, and refraction. High-density OCT grid-wise (60 × 60 grids, each approximately 0.01 mm2 area) thicknesses were custom-extracted from macular cube scans, then compared between iAMD+RPD and iAMD eyes with correction for confounding factors. These "differences (µm)" were clustered and results de-convoluted to reveal mean difference (95% confidence interval [CI]) and topography of the inner retina (retinal nerve fiber, ganglion cell, inner plexiform, and inner nuclear layers) and outer retina (outer plexiform/Henle's fiber/outer nuclear layers, inner and outer segments, and retinal pigment epithelium-to-Bruch's membrane [RPE-BM]). Differences were also converted to Z-scores using normal data.

Results

In iAMD+RPD compared to iAMD eyes, the inner retina was thicker (up to +5.89 [95% CI = +2.44 to +9.35] µm, P < 0.0001 to 0.05), the outer para-central retina was thinner (up to -3.21 [95% CI = -5.39 to -1.03] µm, P < 0.01 to 0.001), and the RPE-BM was thicker (+3.38 [95% CI = +1.05 to +5.71] µm, P < 0.05). The majority of effect sizes (Z-scores) were large (-3.13 to +1.91).

Conclusions

OCT retinal topography differed across all retinal layers between iAMD eyes with versus without RPD. Greater para-central photoreceptor thinning in RPD eyes was suggestive of more advanced degeneration, whereas the significance of inner retinal thickening was unclear. In the future, quantitative evaluation of photoreceptor thicknesses may help clinicians monitor the potential deleterious effects of RPD on retinal integrity.

The Development and Clinical Application of Innovative Optical Ophthalmic Imaging Techniques

The field of ophthalmic imaging has grown substantially over the last years. Massive improvements in image processing and computer hardware have allowed the emergence of multiple imaging techniques of the eye that can transform patient care. The purpose of this review is to describe the most recent advances in eye imaging and explain how new technologies and imaging methods can be utilized in a clinical setting. The introduction of optical coherence tomography (OCT) was a revolution in eye imaging and has since become the standard of care for a plethora of conditions. Its most recent iterations, OCT angiography, and visible light OCT, as well as imaging modalities, such as fluorescent lifetime imaging ophthalmoscopy, would allow a more thorough evaluation of patients and provide additional information on disease processes. Toward that goal, the application of adaptive optics (AO) and full-field scanning to a variety of eye imaging techniques has further allowed the histologic study of single cells in the retina and anterior segment. Toward the goal of remote eye care and more accessible eye imaging, methods such as handheld OCT devices and imaging through smartphones, have emerged. Finally, incorporating artificial intelligence (AI) in eye images has the potential to become a new milestone for eye imaging while also contributing in social aspects of eye care.

Multi-modal and multi-scale clinical retinal imaging system with pupil and retinal tracking

We present a compact multi-modal and multi-scale retinal imaging instrument with an angiographic functional extension for clinical use. The system integrates scanning laser ophthalmoscopy (SLO), optical coherence tomography (OCT) and OCT angiography (OCTA) imaging modalities and provides multi-scale fields of view. For high resolution, and high lateral resolution in particular, cellular imaging correction of aberrations by adaptive optics (AO) is employed. The entire instrument has a compact design and the scanning head is mounted on motorized translation stages that enable 3D self-alignment with respect to the subject's eye by tracking the pupil position. Retinal tracking, based on the information provided by SLO, is incorporated in the instrument to compensate for retinal motion during OCT imaging. The imaging capabilities of the multi-modal and multi-scale instrument were tested by imaging healthy volunteers and patients.

Scotopic Contour Deformation Detection Reveals Early Rod Dysfunction in Age-Related Macular Degeneration With and Without Reticular Pseudodrusen

Purpose

The purpose of this study was to investigate scotopic contour deformation detection (sCDD), and its structural determinants, in participants with intermediate age-related macular degeneration (iAMD) with or without reticular pseudodrusen (RPD).

Methods

Forty-one participants (aged 58–89 years), including 9 with iAMD and RPD, 16 with iAMD only, and 16 controls, underwent functional testing. The sCDD was evaluated with radial frequency arcs presented at 4 loci: ±4 degrees and 8 degrees vertical eccentricity. Scotopic thresholds and dark adaptation (DA) were measured at the same loci. Retinal layers of spectral domain optical coherence tomography (SD-OCT) volume scans were segmented. To establish the concurrent validity of the functional test, we evaluated the fraction of variability in sCDD thresholds explained by SD-OCT data.

Results

The iAMD group had significantly worse sCDD thresholds compared with controls (8 degrees inferior retina: P = 0.004 and the 4 degrees loci: P < 0.02 for both). Elevated sCDD thresholds were observed in iAMD and RPD eyes at loci with normal scotopic thresholds; the opposite was rarely encountered. Elevated sCDD thresholds were also observed in iAMD eyes with normal DA. Elevated sCDD thresholds were associated with increased age and presence of late AMD in the fellow eye. The optimal machine learning model predicted 16% of variability (cross-validated R²) in sCDD thresholds at 8 degrees.

Discussion

A novel scotopic contour deformation task can provide unique information about rod dysfunction in participants with iAMD and RPD not observed with structural and other functional assessments. Rod dysfunction observed with scotopic contour deformation testing was associated with factors linked to risk of AMD progression.

High-Density Optical Coherence Tomography Analysis Provides Insights Into Early/Intermediate Age-Related Macular Degeneration Retinal Layer Changes

Purpose

To topographically map all of the thickness differences in individual retinal layers between early/intermediate age-related macular degeneration (AMDearly/AMDint) and normal eyes and to determine interlayer relationships.

Methods

Ninety-six AMDtotal (48 AMDearly and 48 AMDint) and 96 normal eyes from 192 participants were propensity-score matched by age, sex, and refraction. Retrospective optical coherence tomography (OCT) macular cube scans were acquired, and high-density (60 × 60 0.01-mm2) grid thicknesses were custom extracted for comparison between AMDtotal and normal eyes corrected for confounding. Resultant "normal differences" underwent cluster, interlayer correlation, and dose-response analyses for the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer + Henle's fiber layer (ONL+HFL), inner and outer segment (IS/OS) thickness, and retinal pigment epithelium (RPE) to Bruch's membrane (BM) thickness.

Results

AMDtotal inner retinal clusters demonstrated extensively thinned RNFL, GCL, IPL, and paracentral INL and thickened INL elsewhere, with normal difference means ranging from -8.13 µm (95% confidence interval [CI], -11.12 to -5.13) to 1.58 µm (95% CI, 1.07-2.09) (P < 0.0001 to P < 0.05). Outer retinal clusters displayed thinned paracentral OPL/ONL+HFL, central IS/OS, and peripheral RPE-BM and thickened central RPE-BM, with means ranging from -1.31 µm (95% CI, -2.06 to -0.55) to 2.99 µm (95% CI, 0.97-5.01] (P < 0.0001 to P <0.05). Effect sizes (-2.56 to 9.93 SD), cluster sizes, and eccentricity effects varied. All interlayer correlations were negligible to moderate regardless of AMD severity. Only the RPE-BM was partly thicker with greater AMD severity (up to 5.44 µm; 95% CI, 4.88-6.00; P < 0.01).

Conclusions

From the early stage, AMD eyes demonstrate thickness differences compared to normal with unique topographies across all retinal layers. Poor interlayer correlations highlight that the outer retina inadequately reflects complete retinal health. The clinical importance of OCT assessment across all individual retinal layers in early/intermediate AMD requires further investigation.

Differences in long-term progression of atrophy between neovascular and non-neovascular age-related macular degeneration

PURPOSE

To compare enlargement rates over 5 years of follow-up in geographic atrophy (GA) versus macular atrophy (MA) associated with macular neovascularization (MNV).

DESIGN

Retrospective, longitudinal comparative case series.

PARTICIPANTS

Consecutive series of age-related macular degeneration (AMD) patients with GA (dry) or MA with MNV.

METHODS

Atrophic regions on serial registered fundus autofluorescence (FAF) images were semiautomatically delineated and area measurements were recorded every 6±3 months for the first 2 years of follow-up and at yearly intervals up to 5 years.

MAIN OUTCOME MEASURES

Annual raw and square root transformed atrophy growth rates.

RESULTS

117 eyes of 95 patients were included (61 in the GA and 56 in the MA cohort); 100% and 38.5% of eyes completed 2 and 5 years of follow-up, respectively. Mean baseline lesion size was similar between the two groups (raw: 1.74 vs. 1.53 mmˆ2, p = 0.56; sqrt transformed: 1.17 vs. 1.02 mm, p = 0.26). Overall enlargement rates were greater for the GA cohort (raw: 1.72 vs. 1.32 mmˆ2/year, p = 0.002; sqrt transformed: 0.41 vs. 0.33 mm/year; p = 0.03), as well as the area of atrophy growth at 5 years (raw: +8.06 vs. +4.55 mmˆ2, p = 0.001; sqrt transformed: +1.93 vs. +1.38 mm, p = 0.02). Estimated sqrt transformed area was also significantly greater for the GA cohort at 2 years (1.84 vs. 1.67 mm, p = 0.01).

CONCLUSIONS

Presence of MNV was associated with a slower rate of expansion resulting in overall smaller areas of atrophy over time. These findings support the hypothesis that MNV may protect against the progression of atrophy.

Assessment of Detailed Photoreceptor Structure and Retinal Sensitivity in Diabetic Macular Ischemia Using Adaptive Optics-OCT and Microperimetry

Purpose

The purpose of this study was to assess density and morphology of cone photoreceptors (PRs) and corresponding retinal sensitivity in ischemic compared to nonischemic retinal capillary areas of diabetic eyes using adaptive optics optical coherence tomography (AO-OCT) and microperimetry (MP).

Methods

In this cross-sectional, observational study five eyes of four patients (2 eyes with proliferative diabetic retinopathy (DR) and 3 eyes moderate nonproliferative DR) were included. PR morphology and density was manually assessed in AO-OCT en face images both at the axial position of the inner-segment outer segment (IS/OS) and cone outer segment tips (COSTs). Retinal sensitivity was determined by fundus-controlled microperimetry in corresponding areas (MP-3, Nidek).

Results

In AO-OCT, areas affected by capillary nonperfusion showed severe alterations of cone PR morphology at IS/OS and COST compared to areas with intact capillary perfusion (84% and 87% vs. 9% and 8% of area affected for IS/OS and COST, respectively). Mean reduction of PR signal density in affected areas compared to those with intact superficial capillary plexus (SCP) and deep capillary plexus (DCP) perfusion of similar eccentricity was -38% at the level of IS/OS (P = 0.01) and -39% at the level of COST (P = 0.01). Mean retinal sensitivity was 10.8 ± 5.4 in areas affected by DCP nonperfusion and 28.2 ± 1.5 outside these areas (P < 0.001).

Conclusions

Cone PR morphology and signal density are severely altered in areas of capillary nonperfusion. These structural changes are accompanied by a severe reduction of retinal sensitivity, indicating the importance of preventing impaired capillary circulation in patients with DR.

Location-Specific Thickness Patterns in Intermediate Age-Related Macular Degeneration Reveals Anatomical Differences in Multiple Retinal Layers

Purpose

To examine individual retinal layers’ location-specific patterns of thicknesses in intermediate age-related macular degeneration (iAMD) using optical coherence tomography (OCT).

Methods

OCT macular cube scans were retrospectively acquired from 84 iAMD eyes of 84 participants and 84 normal eyes of 84 participants propensity-score matched on age, sex, and spherical equivalent refraction. Thicknesses of the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer + Henle's fiber layer (ONL_+HFL), inner- and outer-segment layers (IS/OS), and retinal pigment epithelium to Bruch's membrane (RPE-BM) were calculated across an 8 × 8 grid (total 24° × 24° area). Location-specific analysis was performed using cluster_(normal) and grid_(iAMD)-to-cluster_(normal) comparisons.

Results

In iAMD versus normal eyes, the central RPE-BM was thickened (mean difference ± SEM up to 27.45% ± 7.48%, P < 0.001; up to 7.6 SD-from-normal), whereas there was thinned outer (OPL, ONL_+HFL, and non-central RPE-BM, up to −6.76% ± 2.47%, P < 0.001; up to −1.6 SD-from-normal) and inner retina (GCL and IPL, up to −4.83% ± 1.56%, P < 0.01; up to −1.7 SD-from-normal) with eccentricity-based effects. Interlayer correlations were greater against the ONL_+HFL (mean |r| ± SEM 0.19 ± 0.03, P = 0.14 to < 0.0001) than the RPE-BM (0.09 ± 0, P = 0.72 to < 0.0001).

Conclusions

Location-specific analysis suggests altered retinal anatomy between iAMD and normal eyes. These data could direct clinical diagnosis and monitoring of AMD toward targeted locations.

Three-dimensional composition of the photoreceptor cone layers in healthy eyes using adaptive-optics optical coherence tomography (AO-OCT)

Purpose

To assess the signal composition of cone photoreceptors three-dimensionally in healthy retinas using adaptive optics optical coherence tomography (AO-OCT).

Methods

Study population. Twenty healthy eyes of ten subjects (age 23 to 67).

Procedures. After routine ophthalmological assessments, eyes were examined using AO-OCT. Three-dimensional volumes were acquired at 2.5° and 6.5° foveal eccentricity in four main meridians (superior, nasal, inferior, temporal). Cone densities and signal compositions were investigated in four different planes: the cone inner segment outer segment junction (IS/OS), the cone outer segment combined with the IS/OS (ISOS+), the cone outer segment tips (COST) and full en-face plane (FEF) combining signals from all mentioned cone layers. Additionally, reliability of a simple semi-automated approach for assessment of cone density was tested.

Main outcome measures. Cone density of IS/OS, IS/OS+, COST and FEF. Qualitative depiction and composition of each cone layer. Inter-rater agreement of cone density measurements.

Results

Mean overall cone density at all eccentricities was highest at the FEF plane (21.160/mm²), followed by COST (20.450/mm²), IS/OS+ (19.920/mm²) and IS/OS (19.530/mm²). The different meridians and eccentricities had a significant impact on cone density, with lower eccentricity resulting in higher cone densities (p≤.001), which were highest at the nasal, then temporal, then inferior and then superior meridian. Depiction of the cone mosaic differed between all 4 layers regarding signal size and packing density. Therefore, different cone layers showed evident but not complete signal overlap. Using the semi-automated technique for counting of cone signals achieved high inter-rater reliability (ICC > .99).

Conclusions

In healthy individuals qualitative and quantitative changes in cone signals are found not only in different eccentricities and meridians, but also within different photoreceptor layers. The variation between cone planes has to be considered when assessing the integrity of cone photoreceptors in healthy and diseased eyes using adaptive optics technology.

Three-dimensional assessment of para- and perifoveal photoreceptor densities and the impact of meridians and age in healthy eyes with adaptive-optics optical coherence tomography (AO-OCT)

An adaptive optics optical coherence tomography (AO-OCT) system is used to assess sixty healthy eyes of thirty subjects (age 22 to 75) to evaluate how the outer retinal layers, foveal eccentricity and age effect the mean cone density. The cone mosaics of different retinal planes (the cone inner segment outer segment junction (IS/OS), the cone outer segment combined with the IS/OS (ISOS+), the cone outer segment tips (COST), and the full en-face plane (FEF)) at four main meridians (superior, nasal, inferior, temporal) and para- and perifoveal eccentricities (ecc 2.5° and 6.5°) were analyzed quantitatively. The mean overall cone density was 19,892/mm² at ecc 2.5° and 13,323/mm² at ecc 6.5°. A significant impact on cone density was found for eccentricity (up to 6,700/mm² between ecc 2.5° and 6.5°), meridian (up to 3,700/mm² between nasal and superior meridian) and layer (up to 1,400/mm² between FEF and IS/OS). Age showed only a weak negative effect. These factors as well as inter-individual variability have to be taken into account when comparing cone density measurements between healthy and pathologically changed eyes, as their combined effect on density can easily exceed several thousand cones per mm² even in parafoveal regions.

In vivo retinal imaging in translational regenerative research

Regenerative translational studies must include a longitudinal assessment of the changes in retinal structure and function that occur as part of the natural history of the disease and those that result from the studied intervention. Traditionally, retinal structural changes have been evaluated by histological analysis which necessitates sacrificing the animals. In this review, we describe key imaging approaches such as fundus imaging, optical coherence tomography (OCT), OCT-angiography, adaptive optics (AO), and confocal scanning laser ophthalmoscopy (cSLO) that enable noninvasive, non-contact, and fast in vivo imaging of the posterior segment. These imaging technologies substantially reduce the number of animals needed and enable progression analysis and longitudinal follow-up in individual animals for accurate assessment of disease natural history, effects of interventions and acute changes. We also describe the benefits and limitations of each technology, as well as outline possible future directions that can be taken in translational retinal imaging studies.

Visualizing human photoreceptor and retinal pigment epithelium cell mosaics in a single volume scan over an extended field of view with adaptive optics optical coherence tomography

Using adaptive optics optical coherence tomography, human photoreceptors and retinal pigment epithelium (RPE) cells are typically visualized on a small field of view of ∼1° to 2°. In addition, volume averaging is required for visualizing the RPE cell mosaic. To increase the imaging area, we introduce a lens based spectral domain AO-OCT system that shows low aberrations within an extended imaging area of 4°×4° while maintaining a high (theoretical) transverse resolution (at >7 mm pupil diameter) in the order of 2 µm. A new concept for wavefront sensing is introduced that uses light mainly originating from the RPE layer and yields images of the RPE cell mosaic in a single volume acquisition. The capability of the instrument for in vivo imaging is demonstrated by visualizing various cell structures within the posterior retinal layers over an extended field of view.

A Reflectivity Measure to Quantify Bruch's Membrane Calcification in Patients with Pseudoxanthoma Elasticum Using Optical Coherence Tomography

Purpose

Progressive calcification of Bruch's membrane (BM) causes considerable visual morbidity in patients with pseudoxanthoma elasticum (PXE). Since calcification is hyperreflective on optical coherence tomography (OCT), our aim was to measure BM calcification with OCT imaging.

Methods

Case-control study with 45 patients with PXE under 40 years (range, 11-39) and 25 controls (range, 14-39). Spectralis HRA-OCT imaging consisted of seven macular B-scans with 250-µm spacing. Retinal segmentation was performed with the IOWA Reference Algorithms. MATLAB was used to extract and average z-axis reflectivity profiles. Layer reflectivities were normalized to the ganglion cell and inner plexiform layers. Both median and peak layer reflectivities were compared between patients with PXE and controls. The discriminative value of the retinal pigment epithelium (RPE)-BM peak reflectivity was analyzed using receiver operating characteristic analysis.

Results

The reflectivity profile of patients with PXE differed from controls in the outer retinal layers. The normalized median RPE-BM reflectivity was 41.1 (interquartile range [IQR], 26.3-51.9) in patients with PXE, compared with 22.5 (IQR, 19.3-29.5) in controls (P = 2.09 × 10^-3). The normalized RPE-BM peak reflectivity was higher in patients with PXE (67.5; IQR, 42.1-84.2) than in controls (32.7; IQR, 25.7-38.9; P = 2.43 × 10^-5) and had a high discriminative value with an area under the curve of 0.85 (95% confidence interval, 0.76-0.95). In patients with PXE under 40 years, increasing age did not have a statistically significant effect on the RPE-BM peak reflectivity (patients under 20 years: 44.2 [IQR, 40.5-74.6]; 20-30 years: 66.0 [IQR, 45.1-83.8]; 30-40 years: 70.8 [IQR, 49.0-88.0], P = 0.47).

Conclusions

BM calcification can be measured as increased RPE-BM reflectivity in young patients with PXE and has a high discriminative value.

Translational Relevance

In patients with PXE, the OCT reflectivity of Bruch's membrane may be the first biomarker for Bruch's membrane calcification and a valuable ophthalmologic endpoint in clinical trials.

Morphologic and Functional Assessment of Photoreceptors After Macula-Off Retinal Detachment With Adaptive-Optics OCT and Microperimetry

PURPOSE

Limited information is available on morphologic and functional regeneration of photoreceptors after retinal detachment (RD) surgery. This observational clinical study compared morphologic and functional changes of cones after vitrectomy for macula-off retinal detachment.

DESIGN

Prospective, fellow-eye comparative case series.

METHODS

StudyPopulation: Five eyes after vitrectomy with gas for macula-off retinal detachment (retinal detachment eyes, RDE) and 5 healthy fellow eyes (HFE) of 5 patients (mean age 59.8 years, macula-off duration 0.5 days to 5.5 days). ObservationProcedures: Eyes were examined with adaptive-optics optical coherence tomography (AO-OCT), spectral-domain OCT (SDOCT), and microperimetry (MP) at 6 (baseline, BL) and 56 weeks (follow-up, FUP) after 23 gauge pars plana vitrectomy and SF6 gas tamponade. Eight corresponding regions at foveal eccentricities of 2.5° (ecc 2.5°) and 6.5° (ecc 6.5°) were analyzed in every eye. AO-OCT en face images and SD-OCT B-scans were graded regarding irregularity and loss of photoreceptor signals ranging from none to severe changes. The number of detectable cones at height of the inner-outer segment junction (IS/OS) and cone outer segment tips (COST) was counted manually in AO-OCT images. MP with a custom grid was used to assess retinal sensitivity at these locations. MainOutcomeMeasures: Cone density, cone pattern regularity and signal attenuation, retinal sensitivity.

RESULTS

In comparison to HFE, RDE showed highly irregular cone patterns in AO-OCT and irregular outer retinal bands in SDOCT. Despite significant improvement of cone pattern regularity compared to BL (P < .001), 63% of AO images showed remaining cone pattern irregularity and 45.5% of SDOCT B-scans showed severe signal reduction at FUP. In HFE, mean cone density retrieved from IS/OS and COST remained around 20,000/mm² (ecc 2.5°) and 16,000/mm² (ecc 6.5°) at BL and FUP. Cone density of RDE was significantly reduced and ranged between 200/mm² and 15,600/mm² (P < .001) at BL. Despite improvement at FUP (P < .001), mean cone density at IS/OS and COST was still lower compared to HFE and ranged between 7790 and 9555 cones/mm² (P < .001). Mean retinal sensitivity of all measured locations remained 18 dB in HFE and was significantly lower in RDE, with 14.30 dB at BL and 14.64 dB at FUP. Both SDOCT grading and microperimetry sensitivity showed strong correlation with AO-OCT grading and cone density (rho values > 0.750).

CONCLUSIONS

The combination of AO-OCT, SDOCT, and microperimetry is a powerful tool to capture cone regeneration after vitreoretinal surgery. Our study shows that cone morphology and function improve within 56 weeks after RD surgery but structural and functional impairment is still present.