Correlation of retinal sensitivity measured with fundus-related microperimetry to visual acuity and retinal thickness in eyes with diabetic macular edema

Laser-Based Therapy Approaches in the Retina: A Review of Micropulse Laser Therapy for Diabetic Retinopathy

PURPOSE

This review aims to elucidate the mechanisms and clinical utility of subthreshold micropulse laser (SML) therapy in the context of retinal care. Subthreshold or "nondestructive" laser therapy encompasses treatment modalities that induce minimal or no harm to retinal or choroidal tissue and leave no visible sings post-application, while achieving clinical efficacy.

METHODS

A comprehensive review of literature sourced from databases including PubMed, Medline, Embase, Cochrane, and Web of Science was conducted, focusing on articles published before February 2024, and discussing the contemporary use of SML therapy in treating diabetic retinopathy (DR).

RESULTS

The review presents evidence from scientific literature supporting SML therapy as a viable therapeutic approach for management of DR. Across numerous studies, SML therapy has demonstrated safety and additional therapeutic efficacy without causing damage to underlying retinal tissue.

CONCLUSION

Subthreshold laser treatment emerges as a safe strategy for addressing DR. Numerous studies have shown its additional efficacy to anti-VEGF pharmacotherapy, which is the currently approved monotherapy for complications of DR. Ongoing research and clinical investigations aim to further elucidate the mechanisms and optimize the therapeutic advantages of this technology.

Severity of Disorganization of Retinal Layers and Visual Function Impairment in Diabetic Retinopathy

PURPOSE

To evaluate best-corrected visual acuity (BCVA), retina sensitivity (RS), and fixation impairment by microperimetry (MP) due to the presence and severity of disorganization of retinal inner and outer layers (DRIL/DROL) and ischemia in OCT/OCT angiography (OCTA) in diabetic retinopathy (DR).

DESIGN

Retrospective case-control study.

SUBJECTS

Seventy-six eyes (65 patients) with DR were analyzed. Major exclusion criteria were: center-involving diabetic macular edema (DME), significant media opacity, nondiabetic macular pathology, and active proliferative DR. Patients with DRIL and DROL within central 3 mm were enrolled as cases. Patients with DR and no retina disorganization were considered as controls.

METHODS

A detailed grading of MP and OCT/OCTA images using Image J software, and specific Image Manipulation Program was applied to colocalize the presence of retina disorganization and RS. Best-corrected visual acuity and RS were correlated with the disorganization of retina layers' characteristics and grading (grade 1-DRIL; grade 2-DROL; grade 3-DROL plus, with involvement of the ellipsoid zone). The same procedure of colocalization was applied to the vascular layers on OCTA using MATLAB.

MAIN OUTCOME MEASURES

Correlation between BCVA and MP parameters with disorganization of retina layers grading and OCTA parameters.

RESULTS

Best-corrected visual acuity, mean RS within 1 mm and central 3 mm (overall RS [oRS]), perfusion density, vessel density, and geometric perfusion deficit in intermediate and deep capillary plexuses were lower in cases versus controls (P < 0.001). Mean RS within 1 mm (21.4 decibels [dB] ± 2.4 vs. 13.8 dB ± 5.4, P = 0.002), oRS (22.0 dB ± 2.1 vs. 14.4 dB ± 4.6, P < 0.001), and BCVA (76.1 ± 7.4 vs. 61.2 ± 20.4 ETDRS letters; P = 0.02), had a significant decrease from grade 1 to grade 3 retina disorganization. Choriocapillaris flow voids (CC-FVs) increased from grade 1 to grade 3 (DROL plus) (P = 0.004). Overall retina sensitivity and CC-FV were identified as significant predictors of retina disorganization grade with an adjusted coefficient of determination, R2 = 0.45. Cases had more dense scotomas (P = 0.03) than controls with a positive correlation between the worsening of fixation stability and the severity of DRIL/DROL (P = 0.04).

CONCLUSIONS

Microperimetry and BCVA documented a reduction in visual function in patients with DR and disorganization of retina layers at different grades, with greater functional impairment when outer retina layers and photoreceptors are involved. The severity of retina disorganization and the presence of ischemia could serve as a potential biomarker of functional impairment.

FINANCIAL DISCLOSURES

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Subthreshold micropulse diode laser treatment in diabetic macular edema: biological impact, therapeutic effects, and safety

PURPOSE

To introduce the treatment of diabetic macular edema (DME) with subthreshold micropulse diode laser (SMPL), to summarize the biological impact, therapeutic effects, and safety of this treatment, and to discuss the response to DME when SMPL is combined with anti-vascular endothelial growth factor (anti-VEGF) or steroid.

METHODS

The literature search was performed on the PubMed database, with a selection of English-language articles published from 2000 to 2023 with the following combinations of search terms: diabetes macular (o) edema, micropulse laser or subthreshold micropulse laser, anti-vascular endothelial growth factor, and steroid.

RESULTS

SMPL is a popular, invisible retinal laser phototherapy that is inexpensive, safe, and effective in the treatment of DME. It can selectively target the retinal pigment epithelium, reduce the expression of pro-inflammatory factors, promote the absorption of macular edema, and exert a similar and lasting clinical effect to traditional lasers. No significant difference was found in the therapeutic effects of SMPL between different wavelengths. However, HbA1c level and pretreatment central macular thickness (CMT) may affect the therapeutic outcomes of SMPL.

CONCLUSION

SMPL has a slow onset and produces lasting clinical effects similar to conventional photocoagulation. It has been reported that SMPL combined with the intravitreal anti-VEGF injection can significantly reduce the number of injections without influencing the therapeutic effect, which is essential for clinical applications and research. Although 577 nm SMPL is widely used clinically, there are no standardized protocols for SMPL. Additionally, some important problems regarding the treatment of SMPL require further discussion and exploration.

Bibliometric and visualized analysis of diabetic macular edema

PURPOSE

Our aim was to identify recent research trends on diabetic macular edema (DME) and focus on publications from different countries, institutions, and authors.

METHODS

We retrieved and analyzed data from January 1, 2003 to December 31, 2022 on the DME research field from the Web of Science Core Collection (WoSCC) database. Microsoft Excel and VOSviewer were applied to perform visualization analysis and evaluate the trends.

RESULTS

A total of 4482 publications were identified, and the annual global publications increased steadily, from 36 to 390, during this period. The United States (1339 publications, 71,754 citations), Johns Hopkins University (176 publications, 17,015 citations), and Bressler NM (76 publications, 9621 citations) were the most influential and productive countries, institutions, and authors, respectively. The top 100 keywords were classified into five clusters: (1) therapy and adverse effects of DME; (2) clinical biomarkers of DME; (3) mechanistic research on DME; (4) improving bioavailability and efficacy; and (5) early diagnosis of diabetic complications. "Diabetic macular edema," "retinopathy," "ranibizumab," and "optical coherence tomography angiography" were the most frequent keywords. Regarding the average appearing years (AAYs) of the keywords, "deep learning" (AAY:2020.83), "optical coherence tomography angiography" (AAY:2019.59), "intravitreal Aflibercept" (AAY:2019.29), and "dexamethasone implant" (AAY:2019.20) were recognized as the hotspots of the DME research area in the short run.

CONCLUSION

In the past two decades, the United States was in master status in DME research. Although intravitreal drug injection has been the mainstream therapy for a long time, the effectiveness of different drugs, such as dexamethasone, new solutions for drug delivery, such as intravitreal implantation, and more accurate tools for the classification and follow-up of DME patients, such as deep learning systems, are still research hotspots.

Microperimetry in Retinal Diseases

Retinal microperimetry (MP) is a procedure that assesses the retinal sensitivity while the fundus is directly observed, and an eye tracker system is active to compensate for involuntary eye movements during testing. With this system, the sensitivity of a small locus can be accurately determined, and it has become an established ophthalmic test for retinal specialists. Macular diseases are characterized by chorioretinal changes; therefore, the condition of the retina and choroid requires careful and detailed evaluations to perform effective therapy. Age-related macular degeneration is a representative retinal disease in which the macular function has been evaluated by the visual acuity throughout the course of the disease process. However, the visual acuity represents the physiological function of only the central fovea, and the function of the surrounding macular area has not been sufficiently evaluated throughout the different stages of the macula disease process. The new technique of MP can compensate for such limitations by being able to test the same sites of the macular area repeatedly. This is especially useful in the recent management of age-related macular degeneration or diabetic macular edema during anti-vascular endothelial growth factor treatments because MP can assess the effectiveness of the treatment. MP examinations are also valuable in diagnosing Stargardt disease as they can detect visual impairments before any abnormalities are found in the retinal images. The visual function needs to be carefully assessed along with morphologic observations by optical coherence tomography. In addition, the assessment of retinal sensitivity is useful in the presurgical or postsurgical evaluations.

Retinal ultrastructural, electrophysiological, and microvascular morphological outcomes in diabetic macular edema treated with intravitreal bevacizumab

BACKGROUND

Investigation of retinal ultrastructural, electrophysiological, and microvascular morphological changes, as well as correlations between these changes and visual outcome in naïve diabetic macular edema (DME) patients after intravitreal bevacizumab therapy (IVBT).

METHODS

This prospective interventional study enrolled 31 DME patients' eyes treated with monthly IVBT for three months. Best-corrected visual acuity (BCVA) and intraocular pressure (IOP) were measured, and fundus fluorescein angiography, optical coherence tomography (OCT), microperimetry, as well as optical coherence tomography angiography (OCTA) were performed before and after IVBT. Patients were grouped based on BCVA improvement after three consecutive IVBT: group 1: > 10 letters, group 2: ≤ 5 letters, and group 3: between 6 and 10 letters.

RESULTS

Mean BCVA increased significantly from 34.2 to 39.9 letters (p < 0.001). Central macular thickness decreased significantly from 335.1 to 276.4 μm (p < 0.001). Fixation stability, retinal sensitivity, and local deficit all improved significantly (p < 0.001 for all). There was no statistically significant change in IOP (p = 0.665). Although OCTA parameters did not change significantly, lower foveal avascular zone (FAZ) area, higher foveal vessel density 300 μm area around FAZ and deep plexus vascular density were associated with highly improved BCVA, retinal sensitivity, and local deficit. Also, there were no significant intergroup differences in gender, age, baseline BCVA, HbA1c, IOP, phakic/pseudophakic lens ratio, concomitant hypertension, and superficial capillary plexus vascular density.

CONCLUSIONS

IVBT was associated with significantly improved BCVA, retinal ultrastructural integrity, and electrophysiological patterns in naive DME patients. Improvements in retinal electrophysiology correlated with ultrastructural improvements, which could be predicted using OCTA.

Fotopic and scotopic retinal sensitivity and foveal fixation normal values using microperimetry in healthy population

PURPOSE

To determine normal values of fotopic and scotopic retinal sensitivity and foveal fixation obtained by microperimetry, using MP3-S microperimeter (Nidek, Gamagori, Japan), in a healthy population.

METHODS

Observational, crossectional, single centre study. Fotopic and scotopic microperimetry was performed using with a customized 13-point fovea-centered pattern in healthy volunteers without ocular pathology. A intraclass correlation coefficient (ICC) was performed to evaluate fotopic and scotopic microperimetry reliability.

RESULTS

We analyzed 102 eyes of 54 patients with a mean age of 49.8 +/- 15 years old. The fotopic and scotopic mean retinal sensitivity (MRS) was 28.55±3.3dB (95% CI=[27.87-29.23]) and 15.72±1.9dB (95% CI=[15.35-16.09]) respectively, showing a significant statistical difference (p<0.05). No differences were found when comparing SRM by gender group. However, when analyzing the SRM by age groups, statistically significant differences were found in both modalities of the test; SRM being higher in the group of subjects under 35 years of age with 30.3±1.7dB in the photopic and 16.3±1.3dB in the scotopic; and lower in the group of older than 65 years with 26.7±2.2dB in the photopic and 13.8±1.8dB in the scotopic with p=0.0001. The reliability analysis of both tests, revealed an excellent reliability of the fotopic microperimetry with a Crombach alpha of 0.958 and a good reliability of 0.841 in scotopic microperimetry.

CONCLUSIONS

Microperimetry is a test with good reliability both under photopic and scotopic conditions. SRM and fixation stability under photopic and scotopic conditions do not differ according to sex, but it does decrease with age. There is a positive correlation between photopic and scotopic SRM.

The role of retinal focal photosensitivity in micropulse treatment of vascular genesis focal macular edema

Introduction. Vascular macular edema (ME) is the most common in diabetic retinopathy and retinal vein occlusion. To assess the efficacy and safety of ongoing treatment the dynamics of the best-corrected visual acuity is always taken into account, however, taking into consideration the subjectivity of this indicator, objective methods of assessing the morphofunctional state of the retina should be performed. These include optical coherence tomography and microperimetry.

The aim of the study is to evaluate the role of focal retinal photosensitivity (FRP) in assessing the efficacy of micropulse treatment of macular edema of vascular genesis.

Material and methods. The study group consisted of 110 patients (110 eyes) including 74 patients (74 eyes) with diabetic macular edema (DME) up to 500 μm and 36 patients (36  eyes) with ME up to 500  μm caused by branch retinal vein occlusion. The patients were divided into two groups randomly: in the first group micropulse was performed using a green laser (λ = 532 nm), in the second group – a yellow laser (λ = 577 nm).

Results. In both groups ME decreased significantly to 342 ± 11 µm (M ± σ), maximum corrected visual acuity and FRP increased to 0.59 ± 0.07 and 23.9 ± 1.7 dB (M ± σ), accordingly. Statistically significant difference in treatment efficacy depending on laser length wasn’t detected.

Conclusion. FRP in the area of edema of neuroepithelium (NE) has a direct correlation with NE thickness and is an important indicator of the retinal functional state and can be used to develop a personalized approach to patient treatment and assess the effectiveness of ME treatment. Application of micropulse for treatment of vascular genesis focal ME with height up to 500 μm is effective and safe, as it allows to decrease reliably the thickness of NE in the edema zone and improve clinical and functional indices, reliably increase FRP.

[The history and prospects of the microperimetry method in diagnosis of pathologies of the macular region and the optic nerve]

The article discusses the historical development stages of diagnostics of the functional state of the retina and the optic nerve using microperimetry in the Russian Federation and other countries, as well as the features and diagnostic prospects of the microperimetry method in identifying fundus pathologies.

Detecting Diabetic Retinal Neuropathy Using Fundus Perimetry

Fundus perimetry is a new technique for evaluating the light sense in the retina in a point-to-point manner. Light sense is fundamentally different from visual acuity, which measures the threshold for discriminating and perceiving two points or lines, called the minimum cognoscible. The quality of measurement of retinal sensitivity has dramatically increased in the last decade, and the use of fundus perimetry is now gaining popularity. The latest model of fundus perimetry, MP-3, can be used for a wide range of measurements and has an advanced eye tracking system. High background illumination enables accurate measurement of mesopic retail sensitivity. Recent investigations have shown that neuronal damage precedes vascular abnormalities in diabetic retinopathy. The loss of retinal function has also been reported prior to morphological changes in the retina. In this review, the importance of measuring retinal sensitivity to evaluate visual function in the early stages of diabetic retinopathy was discussed. The usefulness of retinal sensitivity as an outcome measure in clinical trials for treatment modalities is also presented. The importance of fundus perimetry is promising and should be considered by both diabetes researchers and clinical ophthalmologists.

Beyond the Visual Acuity: Assessing the Visual Function in mCNV Patients After Anti-VEGF Treatment

Purpose: To investigate visual function and vision-related quality of life (VR-QoL) changes in patients with myopic choroidal neovascularization (mCNV) after ranibizumab treatment.

Methods: Quantitatively evaluate the objective tests of visual function (visual acuity, microperimetry, and metamorphopsia by m-Charts) before and after 3+prn (pro re neta) ranibizumab treatment for 1 year. The National Eye Institute 25-Item Visual Function Questionnaire (VFQ-25) was performed to evaluate the VR-QoL.

Results: A total of 57 eyes of 57 patients were included in this study. The median average metamorphopsia score was 0.65 before treatment and improved to 0.45 after treatment (p = 0.0003). There was also a significant difference in the average threshold, macular integrity, and proportion of patients with stable fixation by the microperimetry (p < 0.000, p < 0.0001, and p = 0.03, respectively). After treatment, the VR-QoL composite, general vision subscale, and vision-related mental health subscale score were increased with borderline or statistical significance (p = 0.088, p = 0.0038, and p = 0.012, respectively). Subgroup analysis demonstrated parallel improvement of the VR-QoL score, metamorphopsia, average macular threshold, and fixation stability in patients with or without visual acuity increase. By multiple linear regression analysis, the VFQ-25 score after anti-VEGF treatment was only associated with the baseline VFQ-25 score and macular integrity. Improvements in the VFQ-25 score were only associated with changes in the metamorphopsia score.

Conclusions: Integral lifting in several aspects of visual function was observed in mCNV after ranibizumab treatment. Macular integrity and metamorphopsia, but not visual acuity, were associated with VR-QoL.

Structural and functional findings in patients with moderate diabetic retinopathy

Purpose

To evaluate structural and functional ocular changes in patients with type 2 diabetes mellitus (DM2) and moderate diabetic retinopathy (DR) without apparent diabetic macular edema (DME) assessed by optical coherence tomography (OCT) and microperimetry.

Methods

This was a single-center cross-sectional descriptive study for which 75 healthy controls and 48 DM2 patients with moderate DR were included after applying exclusion criteria (one eye per patient was included). All eyes underwent a complete ophthalmic examination (axial length, macular imaging with swept-source OCT, and MAIA microperimetry). Macular thicknesses, ganglion cell complex (GCC) thicknesses, and central retinal sensitivity were compared between groups, and the relationships between the OCT and microperimetry parameters were evaluated.

Results

Macular thickness was similar in both groups (242.17 ± 35.0 in the DM2 group vs 260.64 ± 73.9 in the control group). There was a diminution in the parafoveal area thickness in the DM2 group in the GCC complex. Retinal sensitivity was reduced in all sectors in the DM2 group. The central global value was 24.01 ± 5.7 in the DM2 group and 27.31 ± 2.7 in the control group (p < 0.001). Macular integrity was 80.89 ± 26.4 vs 64.70 ± 28.3 (p < 0.001) and total mean threshold was 23.90 ± 4.9 vs 26.48 ± 2.6 (p < 0.001) in the DM2 and control group, respectively. Moderate correlations were detected between the central sector of MAIA microperimetry and retina total central thickness (− 0.347; p = 0.0035). Age, visual acuity, and hemoglobin A1c levels also correlated with retinal sensitivity.

Conclusion

Macular GCC thickness and central retinal sensitivity were reduced in patients with moderate DR without DME, suggesting the presence of macular neurodegeneration.

Macular Thickness Profile and Its Association With Best-Corrected Visual Acuity in Healthy Young Adults

Purpose

To describe the thickness profiles of the full retinal and outer retinal layers (ORL) at the macula in healthy young adults, and associations with best-corrected visual acuity (BCVA).

Methods

In total, 1604 participants (19-30 years) underwent an eye examination that included measurements of their BCVA, axial length, and autorefraction. The retinal thickness at the foveal pit and at the nine Early Treatment of Diabetic Retinopathy Study macular regions (0.5-mm radius around the fovea, and superior, inferior, temporal, and nasal quadrants of the inner and outer rings of the macula) were obtained using spectral-domain optical coherence tomography imaging. A custom program was used to correct for transverse magnification effects because of different axial lengths.

Results

The median full retinal and ORL thicknesses at the central macula were 285 µm and 92 µm. The full retina was thinnest centrally and thickest at the inner macula ring, whereas the ORL was thickest centrally and gradually decreased in thickness with increasing eccentricity. There was no association between axial length and the full retinal or ORL thickness. Increased thicknesses of the full retina at the central macula was associated with better BCVA; however, the effect size was small and not clinically significant.

Conclusions

This article mapped the full retinal and ORL thickness profile in a population-based sample of young healthy adults.

Translational Relevance

Thickness values presented in this article could be used as a normative reference for future studies on young adults and in clinical practice.

An insight on the anatomical and functional consequences of aflibercept therapy in age-related macular degeneration

BACKGROUND

Evaluation of anatomical and functional recovery of the retina after aflibercept therapy in neovascular age-related macular degeneration.

MATERIALS AND METHODS

This prospective study enrolled 33 eyes of 33 naive age-related macular degeneration patients with an average age of 69 (55-82) years. Following a thorough ophthalmological examination, baseline color fundus photography, optical coherence tomography and fluorescein angiography were used to assess the angiographic characteristics and classification of the lesions. Multifocal electroretinography and microperimetry were recorded. In the first three months, all patients received three consecutive intravitreal aflibercept injections on a monthly basis. After the initial three doses, non-responders received additional afibercept injections. The baseline, 3rd and 6th month data were recorded for analysis.

RESULTS

The baseline average best-corrected visual acuity (1.05 log MAR) improved dramatically to 0.9 log MAR in the 3rd and 6th months, respectively. The baseline average central macular thickness of 358.5 ± 232.1 μm decreased significantly to 273.0 ± 109.9 μm and 245.5 ± 109.3 μm in the 3rd and 6th months, respectively. The average thickness of the central 1 mm macular region decreased significantly from 349.5 ± 96.4 μm to the 3rd and 6th month values of 320.6 ± 101.9 and 290.5 ± 86.4 μm, respectively. While the mean retinal sensitivity increased significantly from 4.7 ± 3.0 dB to 6.9 ± 3.4 Db, local deficit decreased from -11.6 ± 4.6 dB to -9.4 ± 4.6 dB. Significant improvements were also observed in all rings of N1 and P1 waves.

CONCLUSION

Intravitreal aflibercept therapy resulted in significant morphological improvements that were easily identifiable during the 3rd month. Electrophysiological improvements were delayed only to become statistically significant in the 6th month. However, it has been shown that visual acuity and optical coherence tomography parameters alone may be insufficient for both the morphological and functional assessment of the retina.

Correlation of macular sensitivity measures and visual acuity to vision-related quality of life in patients with age-related macular degeneration

Background

Visual acuity is commonly used as a functional outcome measure in patients with age-related macular degeneration (AMD), despite having a weak correlation with self-perceived visual quality of life. Microperimetry is a useful method of detecting loss of macular function. We wanted to investigate the relationship between these two objective visual outcome measures and subjective vision-related quality of life, finding out which objective measure is more patient-relevant.

Methods

Fifty-one consecutive patients with AMD were recruited to the study. Participants were required to complete the Visual Function Questionnaire 39, the Early Treatment Diabetic Retinopathy Study visual acuity examination and a microperimetry assessment using the Micro Perimeter 3. One patient withdrew consent and seven patients dropped out due to cooperation difficulties under microperimetry. Forty-three patients with AMD were included in the study: twenty-eight patients with late AMD (exudative AMD) and fifteen patients with early (non-exudative) AMD. The right eye was included as standard, as was the eye with the best-corrected visual acuity.

Results

There was a higher correlation between vision-related quality of life and macular sensitivity (r = 0.458; p = 0.014) than between vision-related quality of life and visual acuity (r = 0.446; p = 0.018) in patients with late AMD. There was a positive correlation between vision-related quality of life and macular sensitivity in patients with early AMD (r = 0.542; p = 0.037) while the correlation between vision-related quality of life and visual acuity in these patients was not statistically significant. Composite score (r = 0.469; p = 0.012) correlated highest with the nasal outer macular sub-region and near-distance activities score (r = 0.652; p < 0.001) correlated highest with the nasal inner macular sub-region in patients with late AMD. Correlations between composite score and macular sub-regions in patients with early AMD were not significant, but near-distance activities score correlated with the nasal outer macular sub-region in these patients (r = 0.469; p = 0.012).

Conclusions

Macular sensitivity as measured using microperimetry correlates with vision-related quality of life in early AMD and in late AMD, showing it to be a patient-relevant outcome measure. Furthermore, the nasal sub-regions of the macula appear to be preferred retinal loci in patients with AMD.

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Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-01901-x.

Impacts of intravitreal anti-VEGF therapy on retinal anatomy and neurophysiology in diabetic macular edema

PURPOSE

To evaluate anatomical and neuroretinal functional aspects in patients with diabetic macular edema (DME) after intravitreal anti-vascular endothelial growth factor (VEGF) therapy, in particular aflibercept.

MATERIALS AND METHODS

This prospective single-centered interventional study was performed at Afyonkarahisar Health Science University Faculty of Medicine, Department of Ophthalmology, where 32 eyes of 32 patients with DME were investigated. All patients received five intravitreal aflibercept injections on a monthly basis and were followed up for ≥ 6 months. After a comprehensive ophthalmological examination, including the measurements of visual acuity and intraocular pressure, and an antero-posterior segment slit-lamp biomicroscopy before and after full pupil dilation, fundus fluorescein angiography and optical coherence tomography were performed at baseline and during the third and sixth months post-therapy. Microperimetry and multifocal electroretinography were also performed at baseline and during the sixth months.

RESULTS

Mean visual acuity increased from 0.73 to 0.57 and 0.33 logarithm of the minimum angle of resolution (logMAR) during the third and sixth months, respectively (p < 0.001). Changes in intraocular pressure were not statistically significant (p = 0.472). There was statistically significantly decreased mean central macular thickness from 390.2 μm to 242.6 and 289.7 μm during the third and sixth months, respectively (p < 0.001). Significantly improved fixation patterns during the sixth month, along with significantly increased macular sensitivity from 8.2 to 14.2 dB (p < 0.001) and significantly decreased local deficit from - 10.3 to 5.5 dB (p < 0.001) were observed. Further, there was a significantly increased N1 amplitude in the first ring and significantly increased P1 amplitude in all rings (p for each parameter < 0.05). There was also significantly decreased N1 wave implicit time in all rings and significantly decreased P1 wave in the second, third, fourth and fifth rings (p for each parameter < 0.05).

CONCLUSIONS

Patients with DME showed profound improvement in the retinal neurophysiological function, which was also accompanied by anatomical and ultrastructural integrity recovery after intravitreal aflibercept therapy. In the pathogenesis of DME, the influence of neurodegeneration has been increasingly gaining significant attention. Consequently, the need to assess neurophysiological effects of anti-VEGF therapy using a variety of diagnostic measures like electrophysiological studies and multimodal imaging technologies is undeniably growing.

Effectiveness of Low Vision Rehabilitation Using Microperimetric Acoustic Biofeedback Training in Patients with Central Scotoma

PURPOSE

To evaluate the efficacy of visual rehabilitation with microperimeter biofeedback in patients with central scotoma.

MATERIALS AND METHODS

35 consecutive patients with central scotoma (17 age-related macular degeneration (AMD), 14 Stargardt disease, and 4 cone dystrophy) were included in the study. Visual acuity, reading performance by Minnesota Low Vision Reading Test (MNREAD), quality of life by 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25), and fixation analysis by MAIA microperimeter were evaluated before and 1 month after training. The rehabilitation program consisted of 10 training sessions of 10 minutes.

RESULTS

The median best-corrected visual acuity (BCVA) was 0.80 logMAR (range 0.3 to 1.3 logMAR). Fifty-nine percent of patients with AMD developed a preferred retinal locus (PRL) nasal to the fovea, and 64% of the patients with Stargardt disease preferred a PRL superior to the fovea. The PRL location in 3 of 4 cone dystrophy patients was nasal to the fovea. The mean PRL distance from the fovea was 7.57 ± 3.61 degrees. Fixation stability improved with P1 values of 22.34 ± 11.81 versus 32.05 ± 18.79 (p = .003) and 95% bivariate contour ellipse area (BCEA) values of 41.6 versus 23.6 (p = .018) before and after training, respectively. There was a significant difference in reading acuity between before and after training (p = 0.008). The overall score and near activities score of NEI VFQ-25 were found to be increased at the end of the rehabilitation (p < 0.001).

CONCLUSION

Rehabilitation with acoustic biofeedback in patients with central scotoma looks like a useful technique for improving fixation stability, reading performance and quality of life.

A novel Bayesian adaptive method for mapping the visual field

Measuring visual functions such as light and contrast sensitivity, visual acuity, reading speed, and crowding across retinal locations provides visual-field maps (VFMs) that are extremely valuable for detecting and managing eye diseases. Although mapping light sensitivity is a standard glaucoma test, the measurement is often noisy (Keltner et al., 2000). Mapping other visual functions is even more challenging. To improve the precision of light-sensitivity mapping and enable other VFM assessments, we developed a novel hybrid Bayesian adaptive testing framework, the qVFM method. The method combines a global module for preliminary assessment of the VFM's shape and a local module for assessing individual visual-field locations. This study validates the qVFM method in measuring light sensitivity across the visual field. In both simulation and psychophysics studies, we sampled 100 visual-field locations (60° × 60°) and compared the performance of qVFM with the qYN procedure (Lesmes et al., 2015) that measured light sensitivity at each location independently. In the simulations, a simulated observer was tested monocularly for 1,000 runs with 1,200 trials/run, to compare the accuracy and precision of the two methods. In the experiments, data were collected from 12 eyes (six left, six right) of six human subjects. Subjects were cued to report the presence or absence of a target stimulus, with the luminance and location of the target adaptively selected in each trial. Both simulations and a psychological experiment showed that the qVFM method can provide accurate, precise, and efficient mapping of light sensitivity. This method can be extended to map other visual functions, with potential clinical signals for monitoring vision loss, evaluating therapeutic interventions, and developing effective rehabilitation for low vision.

Structure-Function Correlation Using OCT Angiography And Microperimetry In Diabetic Retinopathy

Purpose

To evaluate macular vasculature in diabetic retinopathy (DR) with optical coherence tomography angiography (OCTA) and to correlate vessel density (VD) with retinal sensitivity (RS) as a way to assess structural and functional findings in DR.

Design

Prospective observational cross-sectional study.

Methods

Diabetic patients with DR but no clinically significant diabetic macular edema (DME) and healthy subjects were included in this study. All of them underwent comprehensive ophthalmic examination, best corrected visual acuity (BCVA), OCTA with RS-3000 Advance AngioScan (Nidek, Gamagori, Japan) and microperimetry with MP-3 (Nidek, Gamagori, Japan). Retinal vascular density measured by OCT angiography in 9 areas was correlated with RS in the same 9 areas by Spearman correlation.

Results

In this study, 50 subjects were enrolled: 25 eyes of diabetic patients with DR and 25 eyes of non-diabetic subjects. Diabetic patients mean age was 51.88±13.62 years; non-diabetic subjects were 43.48±13.42 years. The BCVA was 20/25 in the diabetic group and 20/20 in the non-diabetic group. Mean RS was decreased in the DR group (27.68±2.71 dB) compared to the non-diabetic group (31.68±1.46 dB) (p<0.05) and in the 9 studied areas (p<0.05). Mean VD was decreased in the DR group compared to non-diabetics (p<0.05) and in 7 of the 9 areas (except temporal superior and inferior squares) (p<0.05). Correlations by areas between VD and RS were assessed, we found moderate correlation in the area temporal to the fovea (r=0.501, p=0.01) in the DR group but not in the non-diabetic subjects. There were no other statistical significant correlations with this pattern.

Conclusion

DR without DME results in a retinal VD decreased that might be the cause of a reduction of RS in one of the studied areas. Microangiopathic changes are correlated with microperimetry sensitivity drop in the temporal to the fovea grid but not in the other studied grids.

Comparison of macular retinal sensitivity and its contribution to the foveal sensitivity between diabetic and non-diabetic patients with normal visual acuity

PURPOSE

To compare the retinal sensitivity and evaluate its contribution to the foveal sensitivity in patients with and without diabetes who maintain normal visual acuity.

METHODS

Observational, descriptive, cross-sectional and prospective study in 20 subjects without diabetes (group 1) and 23 with type 2 diabetes mellitus (group 2) that had no ocular abnormalities. Retinal sensitivity was measured with the macular threshold test by the Humphrey's computerized perimeter. The mean sensitivity in each of the 16 points and the foveal sensitivity were compared between groups using the Mann-Whitney's U test; the correlation between retinal sensitivity and foveal sensitivity was analyzed by the Spearman's test and the contribution of each point to the foveal sensitivity was identified by multiple regression.

RESULTS

Sixty eyes were evaluated, 30 in group 1 and 30 in group 2; the mean foveal sensitivity was 34.77±0.5dB in group 1 and 32.87±0.6 in group 2. The highest sensitivity of the temporal visual field had an inferior paracentral location (point 3) in both groups. In the linear regression analysis, points which contributed to the foveal sensitivity were 1 in group 1 and points 7 and 15 in group 2.

CONCLUSIONS

Subjects without diabetes have a significantly higher sensitivity in the temporal retina compared with those with diabetes; points with highest mean retinal sensitivity do not correspond to the central four. The reduced sensitivity in point 1 decreases the mean foveal sensitivity in subjects with diabetes, because this variable correlates with lower perimetry points.

Robust segmentation of retinal layers in optical coherence tomography images based on a multistage active contour model

Optical Coherence Tomography (OCT) constitutes an imaging technique that is increasing its popularity in the ophthalmology field, since it offers a more complete set of information about the main retinal structures. Hence, it offers detailed information about the eye fundus morphology, allowing the identification of many intraretinal pathological signs. For that reason, over the recent years, Computer-Aided Diagnosis (CAD) systems have spread to work with this image modality and analyze its information. A crucial step for the analysis of the retinal tissues implies the identification and delimitation of the different retinal layers. In this context, we present in this work a fully automatic method for the identification of the main retinal layers that delimits the retinal region. Thus, an active contour-based model was completely adapted and optimized to segment these main retinal boundaries. This fully automatic method uses the information of the horizontal placement of these retinal layers and their relative location over the analyzed images to restrict the search space, considering the presence of shadows that are normally generated by pathological or non-pathological artifacts. The validation process was done using the groundtruth of an expert ophthalmologist analyzing healthy as well as unhealthy patients with different degrees of diabetic retinopathy (without macular edema, with macular edema and with lesions in the photoreceptor layers). Quantitative results are in line with the state of the art of this domain, providing accurate segmentations of the retinal layers even when significative pathological alterations are present in the eye fundus. Therefore, the proposed method is robust enough to be used in complex environments, making it feasible for the ophthalmologists in their routine clinical practice.

Macular integrity assessment to determine the association between macular microstructure and functional parameters in diabetic macular edema

AIM

To respectively evaluate macular morphological features and functional parameters by using spectral-domain optical coherence tomography (SD-OCT) and macular integrity assessment (MAIA) in patients with diabetic macular edema (DME).

METHODS

This prospective, non-controlled, open study included 61 eyes of 38 consecutive patients with DME. All patients underwent best-corrected visual acuity (BCVA) measurement, MAIA microperimetry, and SD-OCT. DME morphology, including central retinal thickness (CRT) and central retinal volume (CRV); integrity of the external limiting membrane (ELM) and photoreceptor inner segment/outer segment (IS/OS) junction; and the deposition of hard macular exudates were assessed within a 1000-µm central subfield area. MAIA microperimetry parameters evaluated were average threshold (AT)-retinal sensitivity, macular integrity index (MI), fixation points within a circle of radius 1° (P1) and 2° (P2), and bivariate contour ellipse area considering 63% and 95% of the fixation points (A63 and A95, respectively).

RESULTS

MI was significantly higher in eyes with disrupted ELM or IS/OS, compared with eyes with intact ELM and IS/OS. Values of BCVA (logMAR), total AT, AT within 1000-µm diameter, P2, A63, A95, and CRT were significantly worse in eyes with disrupted IS/OS, compared with eyes with intact IS/OS. The values of BCVA (logMAR), AT within 1000-µm diameter, and CRT were significantly worse in eyes with disrupted ELM, compared with eyes with intact ELM. These parameters were not significantly different between eyes with or without hard macular exudate deposition. CRV was not significantly different in the presence or absence of the integrity of ELM, IS/OS, or deposition of hard macular exudates. At the center, nasal and temporal sectors of the fovea, significant negative correlations were observed between retinal thickness and AT of the corresponding area. At the inferior and superior sectors of the fovea, no correlations were observed between retinal thickness and AT of the corresponding area. In the intact IS/OS group, significant negative correlations were observed between CRT and central AT. There was no correlation between retinal sensitivity and thickness when the IS/OS layer was disrupted. Multiple linear regression analyses revealed that IS/OS integrity was an independent factor affecting MI.

CONCLUSION

Functional (BCVA and visual field) and morphological parameters (retinal thickness) were significantly associated with an intact IS/OS. Local photoreceptor integrity was a strong predictor of local visual function throughout the retina. MI revealed the functional status in DME, reflecting the IS/OS juction status in the macula.

Effect of infusion pressure during cataract surgery on ganglion cells measured using isolated-check visual evoked potential

AIM

To detect the relationship between infusion pressure and postoperative ganglion cells function.

METHODS

This prospective observational cohort study included sixty-one eyes that underwent uncomplicated cataract surgery. Patients were divided into two groups according to infusion time (IT) recorded using surgery equipment [Group A: IT>IT_mean (27 eyes); Group B: IT<IT_mean (34 eyes)]. Best-corrected visual acuity, isolated-check visual evoked potential (icVEP), microperimetry, and optical coherence tomography examinations were performed preoperatively and 1wk and 1mo postoperatively. The changes in test results were measured with independent-sample t-tests and paired t-tests. Correlation between IT and these changes were analyzed with Pearson's correlation analysis and Spearman correlation analysis.

RESULTS

Neither group showed significant postoperative changes in macular ganglion cell-inner plexiform layer (mGC-IPL) thickness (1-week postoperative: Group A P=0.185, Group B P=0.381; 1-month postoperative: Group A P=0.775, Group B P=0.652). Postoperative mGC-IPL thickness of Group A was not significantly thicker than that of Group B at both post surgery time point (1-week postoperative P=0.913; 1-month postoperative P=0.954). In Group A, the mGC-IPL thickness change 1wk postoperatively was positively correlated with IT (R²=0.156, P=0.0198). A suspected progressive deficit in the magnocellular pathway was also found in Group A 1-month postoperatively [individual observed F (IOF)=0.63±0.70]. Significant increases were observed in postoperative retinal sensitivity measured by microperimetry (1-week postoperative: Group A P=0.015, Group B P<0.001; 1-month postoperative: Group A P=0.005, Group B P<0.001). In Group B, IT was negatively correlated with the increase in macular sensitivity (1-week postoperative: R²=0.372, P<0.001; 1-month postoperative: R²=0.209, P=0.007).

CONCLUSION

Both mGC-IPL thickness and retinal sensitivity increased postoperatively. A suspected progressive deficit in the magnocellular pathway was found in the group with a long IT, which induced more prominent changes.

Different fixation targets affect retinal sensitivity obtained by microperimetry in normal individuals

Purpose

To determine the differences in the retinal sensitivities obtained by microperimetry with a single cross or a circular fixation target in normal individuals.

Methods

Thirty-two eyes of 16 healthy volunteers (mean age 28.9±1.4 years, range 24-44 years) were studied. The retinal sensitivity of the central 0 degrees and of the mean central 2 degrees consisting of 8 points were determined independently using the two different fixation targets with Microperimeter 3. The Goldmann III stimulus with a luminance of 1.0 cd/m² was presented for 200 ms on a white background.

Results

The retinal sensitivity of the central 0 degrees was significantly better with the circular target than that with the cross target (P=0.003, right eyes; P=0.001, left eyes). The mean retinal sensitivity in the central 2 degrees was not significantly different between the cross and circular fixation targets. (P=0.07, right eyes; P=0.08, left eyes).

Conclusion

These results indicate that the circular fixation target is a better target to use to evaluate the central retinal sensitivity. The difference in the retinal sensitivity is most likely due to the cross fixation target overlapping the test stimulus target.

Progression of Retinitis Pigmentosa as Measured on Microperimetry: The PREP-1 Study

PURPOSE

To evaluate yearly progression of retinitis pigmentosa (RP) using microperimetry (MP) performed on Nidek MP1 (NAVIS Software v1.7; Nidek Technologies, Padova, Italy).

DESIGN

Retrospective longitudinal study.

PARTICIPANTS

RP patients with consecutive MP tests (using the same test settings).

METHODS

Data were collected as part of the Photoreceptor Cell Death in Retinitis Pigmentosa Retrospective (PREP-1) study. Visual acuity, fixation stability, mean sensitivity, and regional sensitivity were assessed at baseline and at yearly follow-up appointments. Regional sensitivity was calculated based on 2 methods. Method 1 involved topographical division into central macula (CM) and paracentral macula (PM). Method 2 involved functional division into the edge of scotoma (ES) and the seeing retina (SR). Linear mixed-effects models were used to assess the annual rate of change for each parameter, adjusted for disease duration.

MAIN OUTCOME MEASURES

Annual rate of change of visual acuity, fixation stability, and retinal sensitivities (mean sensitivity and regional sensitivities using methods 1 and 2).

RESULTS

In total, 75 eyes of 39 patients (median age, 56 y; males, 57%) with a follow-up period ranging from 1 to 4 years were reviewed. Visual acuity at baseline was positively correlated with all retinal sensitivity parameters, most strongly with CM sensitivity (r = 0.545, P < 0.001). There was no change in visual acuity (P = 0.075) or fixation stability (P = 0.371) per year. All retinal sensitivity parameters had a significant decline per year (P < 0.001), with a decline of 0.4 decibel (dB) for mean sensitivity, 0.6 dB for CM, 0.3 dB for PM, 1.3 dB for ES, and 1.1 dB for SR. Method 2 identified the greatest number of cases, with a significant decline in regional sensitivity.

CONCLUSION

MP can detect significant changes in regional sensitivity over a 1-year period in patients with RP, even as visual acuity and fixation remain stable. An individualized approach to analyzing retinal sensitivity derived from MP may offer a useful outcome measure for future clinical trials.

Correlation between retinal sensitivity and cystoid space characteristics in diabetic macular edema

PURPOSE

To evaluate the correlation between retinal sensitivity and cystoid space characteristics in eyes with diabetic macular edema (DME).

MATERIALS AND METHODS

Prospective cross-sectional study of 22 subjects with DME (32 treatment-naïve eyes). All study subjects underwent complete ophthalmic examination, including slit-lamp biomicroscopy and dilated fundus examination. All subjects underwent spectral domain optical coherence tomography (SD-OCT) and microperimetry (MP). Intraretinal cystoid space (ICS) volume was generated after manual delineation of cystoid space boundaries using the three-dimensional-OCT software. Various SD-OCT parameters, including retinal thickness, retinal volume, cystoid space volume, cystoid space intensity, and outer retinal structure integrity, were correlated with MP parameters and best-corrected visual acuity (BCVA).

RESULTS

Subject's mean age was 57 ± 9 years. The mean logarithm of minimum angle of resolution BCVA was 0.4 ± 0.2. The intraclass correlation coefficient for inter- and intra-grader assessment of cystoid space volume by manual delineation was 0.99 and 0.99, respectively. Mean total ICS volume was 0.4 ± 0.4 mm 3 and for the foveal center, subfield was 0.1 ± 0.1 mm 3 . Mean retinal sensitivity was 12.89 ± 10 dB; however, foveal retinal sensitivity was 12.3 ± 11.1 dB. We found no significant correlation between BCVA and total cystoid space volume (r = 0.33, P = 0.06). Correlation between total retinal sensitivity and total ICS was negative and nonsignificant (r = -0.17, P = 0.36). Correlation between foveal retinal sensitivity and foveal cystoid space intensity was moderate and marginally significant (r = -0.43, P = 0.05).

CONCLUSION

Total cystoid space volume was not significantly correlated with BCVA or total retinal sensitivity in subjects with DME. Foveal cystoid space optical intensity was negatively correlated with foveal retinal sensitivity. These findings suggest further investigation of cystoid space characteristics in the setting of DME may be of value.

Visual rehabilitation via microperimetry in patients with geographic atrophy: a pilot study

Background

Age-related macular degeneration (AMD) is the leading cause of blindness in the western world. As a consequence of AMD, patients develop structural damage that comprises the fovea and subsequently present loss of central vision, low visual acuity and unstable fixation. Contrary to what happens with anti-angiogenic treatment in neovascular AMD, there is currently no definitive treatment to reverse geographic atrophy progression. The aim of this study was to determine the effectiveness of the visual rehabilitation treatment via microperimetry in patients with geographic atrophy.

Methods

Longitudinal and prospective study, 18 patients with areas of geographic atrophy in their eye of better visual acuity were included. Macular integrity assessment (Maia) microperimeter (CentreVue, Padova, Italy) was used to diagnose retinal fixation and sensitivity in these patients. Based on these data and using the training module available in the equipment, the patients underwent visual rehabilitation sessions intended to allow the patient to establish the best possible fixation in the best area of retinal sensitivity. To determine the training effectiveness, the following variables were compared before and after: visual acuity in LogMAR scale with ETDRS charts, reading speed with Minnesota Low-Vision Reading Test (MN Read), average sensitivity threshold in microperimetry; P1 and 95% Bivariate Contour Ellipse Area (BCEA) values were used for fixation stability measurement.

Results

Mean age was 77 years old (65–92). Visual acuity of the trained eye was on average 0.7 versus 0.6 LogMAR (p = 0.006) before and one week after training. Reading speed, using both eyes, was 47 words per minute (wpm) before training and 69 wpm after training (p = 0.04). Average retinal sensitivity was 14.1 versus 14.6 db (p = 0.4). Fixation stability improved with P1 values of 45% versus 51% (p = 0.05) and 95% BCEA values of 43 versus 25 (p = 0.02) before and after training, respectively.

Conclusions

Visual training via microperimetry in patients with age-related macular degeneration is effective in improving fixation stability, reading speed, and visual acuity, measured one week after training is completed.

Retinitis pigmentosa-associated cystoid macular oedema: pathogenesis and avenues of intervention

Hereditary retinal diseases are now the leading cause of blindness certification in the working age population (age 16–64 years) in England and Wales, of which retinitis pigmentosa (RP) is the most common disorder. RP may be complicated by cystoid macular oedema (CMO), causing a reduction of central vision. The underlying pathogenesis of RP-associated CMO (RP-CMO) remains uncertain, however, several mechanisms have been proposed, including: (1) breakdown of the blood-retinal barrier, (2) failure (or dysfunction) of the pumping mechanism in the retinal pigment epithelial, (3) Müller cell oedema and dysfunction, (4) antiretinal antibodies and (5) vitreous traction. There are limited data on efficacy of treatments for RP-CMO. Treatments attempted to date include oral and topical carbonic anhydrase inhibitors, oral, topical, intravitreal and periocular steroids, topical non-steroidal anti-inflammatory medications, photocoagulation, vitrectomy with internal limiting membrane peel, oral lutein and intravitreal antivascular endothelial growth factor injections. This review summarises the evidence supporting these treatment modalities. Successful management of RP-CMO should aim to improve both quality and quantity of vision in the short term and may also slow central vision loss over time.

Spectral Domain Optical Coherence Tomography Features and Classification Systems for Diabetic Macular Edema: A Review

Spectral domain optical coherence tomography (SD-OCT) is fast becoming the current standard of care for the detection and assessment of diabetic macular edema. With the application of SD-OCT for imaging of retinal microstructure and measurement of retinal thickness, new information regarding disease characteristics has been gathered, which was unrecognized previously. Retinal thickness measurements on SD-OCT have also been used for deciding the management and monitoring of the disease. Since its development, OCT has enhanced the understanding of retinal anatomical changes in diabetic retinopathy. Several authors have used SD-OCT to classify diabetic macular edema with the purpose of correlating the pathophysiology with disease severity. The classification systems have helped monitor the treatment efficacy and provide prognostic information on the treatment outcome. The following review article summarizes these classifications.

Multimodal retinal imaging of diabetic macular edema: toward new paradigms of pathophysiology

The pathophysiology of diabetic macular edema (DME) is multifactorial and partly still unknown. An increasing body of evidence suggests that neurodegeneration and retinal glial cells activation occur even before the earliest clinical manifestation of diabetic retinal vasculopathy. Nowadays, new non-invasive techniques are available to assess and characterize DME, not only in a quantitative perspective, but also making it possible to understand and quantify the pathogenic processes sustaining fluid accumulation. Optical coherence tomography (OCT) allows documenting not only parameters such as macular volume, central and sectorial retinal thickness, fluid localization, and integrity of retinal layers, but also new still poorly investigated reflectivity aspects. Hyperreflective intraretinal spots (HRS) have been detected on OCT scans through the retinal layers, with a presumptive migration pattern towards the external layers during the occurrence of diabetic retinopathy and DME. These HRS have been hypothesised to represent an in-vivo marker of microglial activation. Autofluorescence of the fundus (FAF) also offers a non-invasive imaging technique of DME. The area of increased FAF correlates with the presence of intraretinal fluid and probably retinal glial activation. Microperimetry allows the measurement of retinal sensitivity by testing specific selected retinal areas. Some studies have shown that increased macular FAF in DME correlates better with visual function assessed with microperimetry than with visual acuity, showing that new imaging and functional techniques may help to elucidate DME pathogenesis and to target therapeutical strategies.

Comparing Macular Thickness Measurements in Patients with Diabetic Macular Edema with the Optos Spectral OCT/SLO and Heidelberg Spectralis HRA + OCT

The aim of this study was to compare measurements of macular thickness, obtained from patients with diabetic macular edema, using two spectral-domain optical coherence tomography (SD-OCT) devices. These were the Spectralis Heidelberg Retina Angiograph + Optical Coherence Tomography (HRA + OCT) (Heidelberg Engineering), which is often considered the gold-standard for OCT measurement, and the Spectral Optical Coherence Tomography/Scanning Laser Ophthalmoscopy (OCT/SLO) (Optos plc), which can additionally perform microperimetry, a useful measure of visual function. In this prospective observational study, each eye had SD-OCT performed with both devices on the same day by the same investigator. Mean retinal thickness was calculated, and compared between the devices, for central and parafoveal zones within 3 mm of the fovea. 62 eyes were included. In the central, superior, temporal, inferior and nasal zones respectively, mean retinal thickness with Spectralis HRA+OCT was (in microns) 310, 343, 344, 332 and 340; measurements with Spectral OCT/SLO were 237, 298, 297, 289 and 290. Pearson correlations between the devices were 0.752, 0.85, 0.928, 0.839, and 0.823 (p < 0.0001). Although absolute measurements between the devices were significantly different and therefore not interchangeable, the correlation between the devices was over 75% and statistically significant in all zones. Thus, the Spectral OCT/SLO could reliably be used for SD-OCT in patients who may also require microperimetry assessment.

Correlation of central visual function and ROP risk factors in prematures with and without acute ROP at the age of 6-13 years: the Giessen long-term ROP study

AIM

To correlate light increment sensitivity (LIS) and visual acuity (VA) with birth weight (BW), gestational age (GA) and stage of acute retinopathy of prematurity (ROP) (STG) in premature children at school age.

METHODS

180 children (150 former prematures and 30 age-matched term-born children) were enrolled at age 6-13 years. Former prematures were categorised by the results of the initial ROP screening based on digital wide-field fundus imaging: absence of ROP (n=100) and spontaneously resolved ROP (n=50). The latter group was further subdivided according to their STG (Stg 1; Stg 2; Stg 3). Both groups were categorised into sectors by BW (<1000 g; 1000-1500 g; >1500 g), and GA (≤28 weeks; >28<32 weeks; ≥32 weeks). VA was assessed with Early Treatment of Diabetic Retinopathy Study letters, LIS was measured at 0°, 2.8° and 8° in the visual field (Microperimeter MP1, Nidek Technologies), and spherical equivalent refraction assessed with a Nidek autorefractor (Nidek, Italy).

RESULTS

Central and pericentral LIS (0° and 2.8°) and VA were significantly lower in all groups and sectors compared with term-born controls except for BW >1500 g for LIS and GA >28 to <32 W for VA. No significant differences were found for LIS at 8° in all groups. No correlation was found between LIS and VA on an individual basis.

CONCLUSIONS

Low BW, GA and increasing severity of spontaneously resolving ROP were associated with significantly decreased central visual function. In addition to VA, LIS measurement further describes foveal function and is a unique parameter to assess parafoveal function.

Retinal Sensitivity over Hard Exudates in Diabetic Retinopathy

PURPOSE

To evaluate retinal sensitivity over hard exudates in correlation with the spectral domain optical coherence tomography (SD-OCT) findings in eyes with diabetic retinopathy.

METHODS

Twelve eyes of 10 patients with hard exudates associated with diabetic retinopathy were enrolled in this study. All subjects underwent a complete ophthalmic examination including SD-OCT (Copernicus, Zawiercie, Poland) and microperimetry (MP1; Nidek Technologies, Padova, Italy). Retinal sensitivity was measured, over the areas with hard exudates and compared to corresponding locations devoid of hard exudates, using a semi-automatic program. The size of the hard exudate plaque was measured using the measurement software in the microperimeter. Retinal thickness in the area of the hard exudates and foveal thickness were measured using SD-OCT.

RESULTS

Mean retinal sensitivity over hard exudates was 4.97 ± 4.17 dB which was significantly (P = 0.0001) reduced as compared to locations devoid of hard exudates. No significant correlation (r=-0.23, P = 0.45) was found between the size of the hard exudates and retinal sensitivity. A significant negative correlation was found between retinal sensitivity and retinal thickness at the area of the hard exudates (r=-0.65, P = 0.05), and between retinal sensitivity and foveal thickness (r=-0.91, P = 0.001).

CONCLUSION

In eyes with diabetic retinopathy, retinal sensitivity was reduced due to the presence of hard exudates in the outer retinal layers and retinal thickening but this was not correlated with the size of the hard exudates.

Microperimetric assessment of retinal sensitivity in eyes with diabetic macular edema from a phase 2 study of intravitreal aflibercept

PURPOSE

To evaluate retinal sensitivity in patients with diabetic macular edema who received intravitreal aflibercept injection (IAI) or laser.

METHODS

A substudy included 46 patients from DA VINCI (a randomized, double-masked Phase 2 study) receiving either laser, 0.5 mg IAI every 4 weeks, 2 mg IAI every 4 weeks, 2 mg IAI every 8 weeks after 3 monthly doses (2q8), or 2 mg IAI as-needed after 3 monthly doses for 52 weeks. Retinal sensitivity was measured in one (central), five (one central and four inner), and eight (four inner and four outer) optical coherence tomography subfields.

RESULTS

Mean best-corrected visual acuity improvement in the subgroup at Week 52 was 3.3 letters with laser and ranged from 5.4 to 16.3 letters in the IAI groups. Retinal sensitivity of laser patients at Week 52 was comparable with baseline in the central optical coherence tomography subfield but decreased in the five and eight optical coherence tomography subfields. Compared with laser, retinal sensitivity significantly increased with IAI in the 2q8 and pooled IAI groups in the 5 and 8 optical coherence tomography subfields at Week 52 (P < 0.05).

CONCLUSION

Intravitreal aflibercept injection improved best-corrected visual acuity and retinal sensitivity in this subgroup of patients. Laser may cause a deterioration of macular function that is not detectable with best-corrected visual acuity testing.

Retinal sensitivity in subjects with type 2 diabetes mellitus: Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study (SN-DREAMS II, Report No. 4)

AIM

To evaluate retinal sensitivity (RS) in subjects with diabetes in a population-based study and to elucidate associated risk factors for abnormal RS.

METHODS

A subset of 357 subjects from Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study-II was included in this study. All subjects underwent detailed ophthalmic evaluation including microperimetry and spectral domain optical coherence tomography.

RESULTS

The prevalence of abnormal mean retinal sensitivity (MRS) was 89.1%. MRS was significantly reduced in subjects with diabetes but no retinopathy when compared with non-diabetic subjects. MRS was reduced in moderate non-proliferative diabetic retinopathy (DR) and macular oedema (ME) at 8° (p=0.04, p=0.01, respectively) and in ME at 10° (p=0.009) and 12° (p=0.036) compared with no DR. Significant negative correlation was found between MRS and best corrected visual acuity, duration of diabetes, glycosylated haemoglobin and central foveal thickness. Increased retinal thickness remained a significant risk factor (OR, 1.02; p=0.044) for abnormal MRS. Altered inner retinal layers and foveal contour were associated with reduced MRS among subjects with DR and presence of epiretinal membrane, altered foveal contour and altered retinal pigment epithelium were associated with reduced MRS.

CONCLUSIONS

Reduced RS in those subjects with diabetes but no retinopathy suggests the early neuronal damage in type 2 diabetes mellitus.

Fixation characteristics among subjects with diabetes: SN-DREAMS II, Report No. 5

OBJECTIVE

To evaluate fixation and scotoma characteristics among subjects with diabetes in a population-based study.

DESIGN

Cohort study.

PARTICIPANTS

A subset of 357 subjects was recruited from follow-up cohort of Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study I.

METHODS

All subjects underwent detailed ophthalmic evaluation including microperimetry and spectral domain optical coherence tomography. Fixation parameters such as stability of fixation, fixation location, and presence of scotoma were evaluated. A p value less than 0.05 was considered statistically significant.

RESULTS

The mean age of the study sample was 56.86 ± 8.63 years. Relatively unstable fixation was observed in 73 and poor central fixation in 25 subjects. Among subjects with poor central fixation, 72% (18 subjects) had relatively unstable fixation. Poor central and relatively unstable fixation were significantly associated with best corrected visual acuity (BCVA; p = 0.002 and p = 0.017, respectively). Prevalence rate of scotoma was 24.4%, which was highly prevalent in females (p = 0.035) and among subjects with reduced BCVA (p < 0.001), reduced contrast sensitivity (p < 0.001), cataract (p < 0.001), impaired retinal sensitivity (p < 0.001), and presence of sight-threatening diabetic retinopathy (STDR; p < 0.001). Presence of scotoma was significantly associated with abnormal foveal contour (p = 0.046) and altered inner retinal layers (p < 0.001).

CONCLUSIONS

We report that fixation characteristics are independent of ocular characteristics except for BCVA. Female sex, reduced visual acuity and contrast sensitivity, cataract, and STDR were significantly associated with presence of scotoma.

Modern diagnostic and treatment aspects of diabetic macular edema

Diabetic macular oedema (DMO) is the leading cause of vision loss and disability in working-age people with diabetes mellitus. This literature review describes pathogenetic mechanisms, concepts, diagnostic techniques and capabilities of novel laser technologies in the treatment of DMO. In recent years, the role of cytokines and growth factors in retinal neurodegeneration has been actively investigated. Modern diagnostic techniques for the treatment of diabetic macular oedema, in addition to conventional techniques, include optical coherence tomography, autofluorescence and microperimetry. These techniques allow the visualization of retinal structures and its functional condition, and they can be used to detect DMO at early stages and to provide the most effective treatment. The evolution of laser technology resulted in the formation of new approaches to DMO treatment. Subthreshold micropulse laser (SML) treatment, in conjunction with conventional photocoagulation, has pronounced therapeutic effects. SML shows high selectivity towards retinal pigment epithelium while avoiding neurosensory retina injury. Owing to the chronic nature of DMO and pathogenetic mechanisms recently discovered, further elaboration of the SML technique appears to be a very promising treatment.

Assessment of Central Retinal Sensitivity Employing Two Types of Microperimetry Devices

PURPOSE

To compare the retinal sensitivity measurements obtained with two microperimeters, the Micro-Perimeter 1 (MP-1) and the Optos optical coherence tomography (OCT)/scanning laser ophthalmoscope (SLO) in subjects with and without maculopathies.

METHODS

Forty-five eyes with no known ocular disease and 47 eyes with maculopathies were examined using both microperimeters. A contrast-adjusted scale was applied to resolve the different stimuli and background luminance existing between the two devices.

RESULTS

There was a strong ceiling effect with the MP-1 in the healthy group, with 90.1% (1136 of 1260) test points clustered at 20 dB. The mean sensitivity for the corresponding points in the OCT/SLO was 25.8 ± 1.9 dB. A floor effect was also observed with the OCT/SLO in the maculopathy group with 9.7% (128 of 1316) points clustered at 9-dB values. The corresponding mean sensitivity in the MP-1 was 1.7 ± 3.9 dB. A regression equation between the two microperimeters was established in the common 10 to19 dB intervals as: OCT/SLO = 15.6 + 0.564 × MP-1 - 0.009 × MP-1² + k (k is an individual point constant; MP-1 coefficient P < 0.001; MP-1² coefficient P = 0.006).

CONCLUSION

The OCT/SLO and the MP-1 provide two different ranges of contrasts for microperimetry examination. Broadening the dynamic range may minimize the constraint of the ceiling and floor effect. There is a significant mathematical relationship in the common interval of the contrast scale.

TRANSLATIONAL RELEVANCE

Applying a unified and broadened dynamic range in different types of microperimeters will help to generate consistent clinical reference for measurements.

The correlation between retinal sensitivity assessed by microperimetry and contrast sensitivity in diabetic macular oedema

AIM

To investigate the relationship between contrast sensitivity (CS) and retinal sensitivity (RS) assessed by microperimetry (MP) in diabetic retinopathy (DR) with clinically significant macular oedema (CSME).

METHODS

A retrospective study was performed with 35 eyes of 35 patients with DR and CSME. Retinal thickness (RT) and MP were tested with the spectral SD-optical coherence topography/scanning laser ophthalmoscope system. Mean central RT at the fovea centre's 1 mm zone (CRT) and at the fixation centre's 1 mm zone (FCRT) was measured. RS was tested at the fixation centre, within 2° and 4° areas. CS was measured with six target sizes (6.3°, 4.0°, 2.5°, 1.6°, 1.0°, 0.64°) with a contrast glare tester.

RESULTS

The mean CRT and FCRT were 344.3±136.2 and 359.9±135.5 μm, respectively. Mean log CSs (-log10) with the six target sizes ranged from 0.19 to 1.32. The mean RS at the fixation centre, within 2°, and within 4° area were 8.51±4.81 dB, 8.58±3.88 dB and 9.22±3.56 dB, respectively. RS at all tested areas were significantly correlated to log CS with all target sizes (range, r=0.366-0.755; p=0.0001-0.030). CRT and FCRT were not significantly correlated to log CS or RS.

CONCLUSIONS

CS and RS showed moderately significant correlations in CSME. However, neither CS nor RS was correlated with RT in patients with CSME. It could be that CS and MP are complementary to each other and are useful tools in the evaluation of functional vision.

A randomized trial to assess functional and structural effects of ranibizumab versus laser in diabetic macular edema (the LUCIDATE study)

PURPOSE

To compare the functional and structural effects of ranibizumab versus macular laser therapy in patients with center-involving diabetic macular edema.

DESIGN

Prospective, randomized, single-masked clinical trial.

METHODS

SETTING

Single center.

STUDY POPULATION

Thirty-three eyes of 33 patients with center-involving diabetic macular edema, with best corrected visual acuity of 55 to 79 Early Treatment Diabetic Retinopathy Study letters at baseline, completing the 48-week study period.

INTERVENTION

Subjects were randomized 2:1 to 3 loading doses of ranibizumab then retreatment every 4 weeks as required; or macular laser therapy at baseline, repeated as required every 12 weeks. Exploratory Outcome Measures: Structural imaging studies included greatest linear dimension and area of foveal avascular zone, perifoveal capillary dropout grade, and presence of morphologic features of diabetic macular edema on Spectralis optical coherence tomography (Heidelberg Engineering GmbH, Heidelberg, Germany). Functional measures: Visual acuity, retinal sensitivity in the central 4 and 12 degrees on microperimetry, color contrast sensitivity protan and tritan thresholds, pattern and full-field electroretinogram amplitudes and implicit times, and multifocal electroretinogram amplitude distribution. These were reported at 12, 24, and 48 weeks.

RESULTS

Ranibizumab-treated subjects gained 6.0 vs 0.9 letters lost for laser, demonstrated improved tritan and protan color contrast thresholds, and improved retinal sensitivity. Electrophysiologic function also improved after ranibizumab therapy. No safety issues were evident. Better retinal thickness reduction and structural improvement in optical coherence tomography features of diabetic macular edema were seen with ranibizumab therapy than in the laser group. There was no evidence of progressive ischemia with ranibizumab therapy.

CONCLUSIONS

Ranibizumab therapy in the treatment of diabetic macular edema seems to improve retinal function and structure as demonstrated by this evaluation of different assessment methods.

Efficacy of SLO-Microperimetry and Humphrey for evaluating macular sensitivity changes in advanced glaucoma

OBJECTIVE

To compare the efficacy of scanning laser ophthalmoscope microperimetry (SLO-MP) and Humphrey visual fields in detecting macular sensitivity changes in advanced glaucoma.

DESIGN

Prospective cohort study.

PARTICIPANTS

25 patients with advanced primary open angle glaucoma and 2 consecutive abnormal Humphrey 10-2 SITA Standard visual field tests.

METHODS

Thirty-six eyes of 25 patients with 2 consecutive abnormal Humphrey 10-2 SITA Standard (H10) visual fields were retested with a modified 10-2 SLO-MP within 3 months of the last reliable H10. A standardized grid was used to mark the macula. Primary outcome was change in mean macular sensitivity (dB; H10 and SLO-MP) in relation to mean macular retinal nerve fibre layer (RNFL) thickness (µm) by SLO- optical coherence tomography (SLO-OCT). Secondary outcome was comparison of reliability indices for both tests. Linear regression was used for analysis.

RESULTS

Mean macular sensitivity was significantly lower in SLO-MP (9.33 ± 3.37 dB) than H10 (18.83 ± 6.46 dB; p < 0.0001). Mean macular RNFL thickness correlated significantly with retinal sensitivity by both SLO-MP (r = 0.39, p < 0.02) and H10 (r = 0.37, p < 0.03). Fixation losses were better controlled in SLO-MP (0.38 ± 1.1) than H10 (4.28 ± 7.9; p = 0.008). False-positive responses were similar (SLO-MP: 2.25 ± 4.53, H10: 1.78 ± 3.33; p = 0.80). A statistically significant difference was noted in the false-negative responses (SLO-MP: 26.87 ± 25.24, H10: 5.33 ± 9.70; p < 0.0001).

CONCLUSIONS

Macular sensitivity determined by both H10 and SLO-MP correlates significantly with mean macular RNFL thickness measured by SLO-OCT. Precise localization of the macula in SLO-MP results in lower fixation losses. Detection of denser field defects by SLO-MP results in higher false-negative responses. A larger sample size is needed to further study the value of this diagnostic tool.

Is there a correlation between structural alterations and retinal sensitivity in morphological patterns of diabetic macular edema?

Spectral domain optical coherence tomography (SDOCT) enables enhanced visualization of retinal layers and delineation of structural alterations in diabetic macular edema (DME). Microperimetry (MP) is a new technique that allows fundus-related testing of local retinal sensitivity. Combination of these two techniques would enable a structure-function correlation with insights into pathomechanism of vision loss in DME. To correlate retinal structural derangement with retinal sensitivity alterations in cases with diabetic macular edema, using SDOCT and MP. Prospective study of 34 eyes of 30 patients with DME. All patients underwent comprehensive ophthalmic examination, fluorescein angiography, microperimetry and SDOCT. Four distinct morphological patterns of DME were identified- diffuse retinal thickening (DRT), cystoid macular edema (CME), schitic retinal thickening (SRT) and neourosensory detachment (NSD) of fovea. Some retinal loci presented with a mixture of above patterns There was significant difference in retinal thickness between groups (P<0.001). Focal retinal sensitivity measurement revealed relatively preserved retinal sensitivity in areas with DRT (13.8 dB), moderately reduced sensitivity (7.9 dB) in areas with CME, and gross retinal sensitivity loss in areas with SRT (1.2 dB) and NSD (4.7 dB) (P<0.001). Analysis of regional scotoma depth demonstrated similar pattern. Retinal sensitivity showed better correlation to OCT pattern (r=-0.68, P<0.001) than retinal thickness (r=-0.44, P<0.001). Structure-function correlation allows better understanding of the pathophysiology of visual loss in different morphological types of DME. Classification of macular edema into these categories has implications on the prognosis and predictive value of treatment.