Association between photoreceptor integrity and visual outcome in diabetic macular edema

Ellipsoid zone on optical coherence tomography: a review

Emergence of the high-resolution optical coherence tomography has allowed better delineation of retinal layers, and many of the anatomical correlations of these layers have now been agreed upon. However, some anatomical correlates still remain contentious, such as the second hyper-reflective band, which is now termed ellipsoid zone. Despite the lack of consensus of the actual origin of the ellipsoid zone, there has been much interest in evaluating its integrity and intensity in different disease processes. This review paper aims to provide an overview of the ellipsoid zone and its clinical and research applications.

Enface Thickness Mapping and Reflectance Imaging of Retinal Layers in Diabetic Retinopathy

Purpose

To present a method for image segmentation and generation of enface thickness maps and reflectance images of retinal layers in healthy and diabetic retinopathy (DR) subjects.

Methods

High density spectral domain optical coherence tomography (SDOCT) images were acquired in 10 healthy and 4 DR subjects. Customized image analysis software identified 5 retinal cell layer interfaces and generated thickness maps and reflectance images of the total retina (TR), inner retina (IR), outer retina (OR), and the inner segment ellipsoid (ISe) band. Thickness maps in DR subjects were compared to those of healthy subjects by generating deviation maps which displayed retinal locations with thickness below, within, and above the normal 95% confidence interval.

Results

In healthy subjects, TR and IR thickness maps displayed the foveal depression and increased thickness in the parafoveal region. OR and ISe thickness maps showed increased thickness at the fovea, consistent with normal retinal anatomy. In DR subjects, thickening and thinning in localized regions were demonstrated on TR, IR, OR, and ISe thickness maps, corresponding to retinal edema and atrophy, respectively. TR and OR reflectance images showed reduced reflectivity in regions of increased thickness. Hard exudates appeared as hyper-reflective spots in IR reflectance images and casted shadows on the deeper OR and ISe reflectance images. The ISe reflectance image clearly showed the presence of focal laser scars.

Conclusions

Enface thickness mapping and reflectance imaging of retinal layers is a potentially useful method for quantifying the spatial and axial extent of pathologies due to DR.

Comparison of retinal thicknesses measured using swept-source and spectral-domain optical coherence tomography devices

BACKGROUND AND OBJECTIVE

To compare retinal thicknesses measured using swept-source optical coherence tomography (SS-OCT) and spectral-domain (SD) OCT devices.

PATIENTS AND METHODS

In a cohort study of 76 healthy eyes and 21 eyes with high myopia, mean retinal thicknesses in ETDRS subfields were compared between OCT scans obtained from the Topcon DRI OCT-1 (Topcon, Tokyo, Japan), Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany), and Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, CA).

RESULTS

Central retinal thickness measurements differed significantly among the three OCT devices (Spectralis: 271 µm; Cirrus: 254 µm; DRI OCT-1: 238 µm; P < .001), with mean differences ranging from 15.6 µm to 37 µm. Intraclass correlation coefficients were at least 0.94 for any pair of machines. Similar results were observed in all nine ETDRS subfields. In all sectors, retinal thickness measurements obtained using the 3-D and radial scans of the SS-OCT were similar (mean differences: 0.7 to 3.8 µm).

CONCLUSION

Retinal thickness measurements obtained from DRI OCT-1 and SD-OCT are different and should be accounted for when comparing results of OCT scans from different devices.

Evaluation of inner and outer retinal thickness in patients receiving intravitreal ranibizumab injections for diabetic macular edema

PURPOSE

To measure inner and outer retinal thickness with optical coherence tomography (OCT) in patients in whom intravitreal ranibizumab was administered due to diabetic macular edema (DME) and to investigate its relation to the visual prognosis.

METHODS

In this retrospective case series, there were 60 consecutive eyes with DME in which intravitreal ranibizumab injection was performed for 3 times in 1-month intervals. All patients underwent full ophthalmic examination and spectral-domain OCT (SD-OCT). The total retinal thickness, the inner thickness, and the outer thickness in 4 parafoveal subfields were measured. The correlation between the retinal thickness and logMAR best-corrected visual acuity (BCVA) was investigated.

RESULTS

No significant correlation was found between the total retinal thickness in the central and other subfields and either the baseline or final visit logMAR BCVA values (p&gt;0.05). There was a significant positive correlation between the final visit logMAR BCVA values and pretreatment inner retinal thickness in the nasal and inferior subfields (r = 0.270, p = 0.037, and r = 0.410, p = 0.001, respectively). There was significant negative correlation between the final visit logMAR BCVA values and pretreatment outer retinal thickness in nasal and temporal parafoveal subfields (r = -0.297, p = 0.021, and r = -0.268, p = 0.038, respectively).

CONCLUSIONS

It could be beneficial to use inner and outer retinal thickness instead of total retinal thickness in determination of short-term prognosis in patients who had intravitreal ranibizumab injection for DME.

Association between macular perfusion and photoreceptor layer status in diabetic macular edema

PURPOSE

To evaluate the relationship between the photoreceptor layer status (inner segment ellipsoid band and external limiting membrane) and the foveal avascular zone size, as a result of macular perfusion, in patients with diabetic macular edema.

METHODS

This observational case series study included 151 eyes of 118 patients with naive diabetic macular edema. The length of the disrupted photoreceptor layer was assessed by optical coherence tomography. The foveal avascular zone diameter was measured on fluorescein angiogram.

RESULTS

No significant association was found between the foveal avascular zone size and the mean lengths of the disrupted inner segment ellipsoid band nor the external limiting membrane in patients with naive diabetic macular edema.

CONCLUSION

Macular ischemia, which lengthens the distance from the perifoveal vessels to the center of the fovea and may disrupt the normal flow of nutrients by simple diffusion to the photoreceptor line, does not seem to influence on inner segment ellipsoid band nor external limiting membrane integrity. Future studies may evaluate the effect of choroidal vascularization on the photoreceptor layer status to enhance the knowledge about the photoreceptor layer nutrients source.

Optical coherence tomographic reflectivity of cystoid spaces is related to recurrent diabetic macular edema after triamcinolone

PURPOSE

To determine the association between reflectivity levels in foveal cystoid spaces on optical coherence tomography images and the course of the logarithm of the minimum angle of resolution (logMAR) after triamcinolone acetonide treatment for diabetic macular edema.

METHODS

We retrospectively reviewed 58 consecutive eyes treated with an intravitreal or sub-Tenon's injection of triamcinolone acetonide for diabetic macular edema. The foveal cystoid spaces within central 1 mm were circumscribed, followed by measurement of optical coherence tomography reflectivity. The correlation between the reflectivity and visual outcome was investigated.

RESULTS

The optical coherence tomography reflectivity levels in foveal cystoid spaces increased at 1 month after treatment, but not at 3 months or 6 months. The preoperative reflectivity levels were correlated negatively with logMAR changes from 1 month to 6 months and from 3 months to 6 months but not with logMAR at individual time points compared with the preoperative logMAR. The changes in foveal thickness from 1 month to 6 months were correlated negatively with the baseline reflectivity and positively with logMAR changes from 1 month to 6 months and from 3 months to 6 months.

CONCLUSION

Lower optical coherence tomography reflectivity in foveal cystoid spaces was associated with the rebound in macular thickening and visual deterioration after triamcinolone acetonide treatment for diabetic macular edema.

Nitric oxide and oxidative stress is associated with severity of diabetic retinopathy and retinal structural alterations

BACKGROUND

The aim of the study was to determine plasma nitric oxide (NO) and lipid peroxide (LPO) levels in diabetic retinopathy and its association with severity of disease.

DESIGN

Prospective observational study.

PARTICIPANTS

A total of 60 consecutive cases and 20 healthy controls were included.

METHODS

Severity of retinopathy was graded according to early treatment diabetic retinopathy study (ETDRS) classification. Photoreceptor inner segment ellipsoid band (ISel) disruption and retinal pigment epithelium (RPE) alteration were graded using spectral domain optical coherence tomography. Data were statistically analyzed.

MAIN OUTCOME MEASURES

Plasma thiobarbituric acid reactive substances, NO assay and reduced glutathione (GSH) were measured using standard protocol.

RESULTS

Increased severity of diabetic retinopathy was significantly associated with increase in plasma levels of LPO (P < 0.05), NO (P < 0.001) and decrease in plasma levels of GSH (P < 0.0001), ISel disruption (P < 0.001) and RPE topographic alteration (P < 0.01).

CONCLUSION

Increased plasma NO levels are associated with increased severity of diabetic retinopathy. For the first time, it has been demonstrated that increased plasma LPO, NO and decreased GSH levels are associated with in vivo structural changes in inner segment ellipsoid and RPE.

Correlation Between Visual Function and Photoreceptor Integrity in Diabetic Macular Edema: Spectral-Domain Optical Coherence Tomography

PURPOSE

To evaluate the relationship between visual function and (i) microstructural changes in the fovea of the inner segment-outer segment junction (IS/OS) and (ii) external limiting membrane (ELM) in diabetic macular edema (DME).

METHODS

We conducted a retrospective, observational, cross-sectional study of 40 DME patients (61 eyes), all of whom had been treated at Shanghai First People's Hospital. Patients were divided into groups based on integrity of the IS/OS or ELM: IS/OS (+, ± and -) and ELM (+, ± and -). We performed best-corrected visual acuity (BCVA), MP1 microperimetry and spectral-domain optical coherence tomography (SD-OCT) on all patients. Several variables, including IS/OS and ELM integrity, central macular thickness (CMT) and central macular volume (CMV), were evaluated by two observers, each masked to patients' BCVA. Main outcome measures included determination of the association of visual function with SD-OCT results.

RESULTS

Significant differences were found between IS/OS (+), IS/OS (±) and IS/OS (-) groups in BCVA (66.88 ± 7.89, 51.60 ± 9.39, 32.64 ± 17.93 letters, p < 0.001); macular sensitivity (MS; 8.21 ± 2.91, 3.55 ± 2.75, 2.72 ± 1.86 dB, p < 0.001); fixation stability within 2° (82.09 ± 12.76, 66.43 ± 29.54, 33.73 ± 29.51%, p < 0.001); and % central fixation (74.87 ± 16.88, 61.39 ± 31.38, 31.64 ± 31.89%, p < 0.001); but no differences were found for CMT (p = 0.069) or CMV (p = 0.069). Results were similar for ELM groups. There were significant differences between ELM (+), ELM (±) and ELM (-) groups in BCVA (64.16 ± 9.49, 50.44 ± 9.83, 32.73 ± 17.98 letters, p < 0.001); MS (7.54 ± 3.22, 3.38 ± 2.38, 2.20 ± 1.72 dB, p < 0.001); fixation stability within 2° (81.48 ± 15.26, 61.12 ± 31.63, 35.00 ± 29.07%, p < 0.001); and % central fixation (75.90 ± 17.33, 55.88 ± 30.94, 30.09 ± 33.00%, p < 0.001); but not for CMT (p = 0.216) or CMV (p = 0.202). There was a strong correlation (r = 0.881, p < 0.001) between ELM and IS/OS integrity for the same patient. Categories of IS/OS showed more severe changes than did those of ELM.

CONCLUSIONS

Both IS/OS and ELM integrity correlated positively with visual function in DME patients. Further studies are needed to confirm and validate this relationship.

Spectral domain optical coherence tomography predictors of visual outcome in diabetic cystoid macular edema after bevacizumab injection

PURPOSE

To study prognostic spectral domain optical coherence tomography parameters in diabetic cystoid macular edema after anti-vascular endothelial growth factor therapy.

METHODS

Retrospective cohort study included 49 eyes with the new onset diabetic cystoid macular edema that had to have a macular spectral domain optical coherence tomography and fluorescein angiography at presentation. The baseline optical coherence tomography scans were analyzed for variables indicative of the extent of retinal involvement by the cystoid change and its location about the center. Univariate and multivariate analyses were performed comparing the optical coherence tomography findings between the two groups of eyes: the "No improvement" and the "Improvement" groups, based on at least two Snellen lines improvement after treatment.

RESULTS

There were 30 and 19 eyes in the No improvement and Improvement groups, respectively. In the univariate analysis, the baseline optical coherence tomography parameters associated with visual improvement included the photoreceptor inner segments thickness centrally (P = 0.009) and within the central 1-mm subfield (P < 0.0001), and the presence of bridging retinal processes centrally (P = 0.004). Multivariate analysis showed both presence and central location of bridging retinal processes within the central 1-mm subfield to be significantly associated with visual improvement (P = 0.041 and 0.005, respectively), with an odds ratio of 13.4 (95% confidence interval, 1.336-636.18; P = 0.010) for their central location.

CONCLUSION

In diabetic cystoid macular edema, visual improvement after anti-vascular endothelial growth factor therapy is more likely to occur in eyes with residual central retinal processes on baseline macular spectral domain optical coherence tomography. This finding may be helpful in patient counseling, case selection, and clinical trial planning.

Photoreceptors in diabetic retinopathy

Although photoreceptors account for most of the mass and metabolic activity of the retina, their role in the pathogenesis of diabetic retinopathy has been largely overlooked. Recent studies suggest that photoreceptors might play a critical role in the diabetes-induced degeneration of retinal capillaries, and thus can no longer be ignored. The present review summarizes diabetes-induced alterations in photoreceptor structure and function, and provides a rationale for further study of a role of photoreceptors in the pathogenesis of the retinopathy.

Wide-Field Megahertz OCT Imaging of Patients with Diabetic Retinopathy

PURPOSE

To evaluate the feasibility of wide-field Megahertz (MHz) OCT imaging in patients with diabetic retinopathy.

METHODS

A consecutive series of 15 eyes of 15 patients with diagnosed diabetic retinopathy were included. All patients underwent Megahertz OCT imaging, a close clinical examination, slit lamp biomicroscopy, and funduscopic evaluation. To acquire densely sampled, wide-field volumetric datasets, an ophthalmic 1050 nm OCT prototype system based on a Fourier-domain mode-locked (FDML) laser source with 1.68 MHz A-scan rate was employed. RESULTS. We were able to obtain OCT volume scans from all included 15 patients. Acquisition time was 1.8 seconds. Obtained volume datasets consisted of 2088 × 1044 A-scans of 60° of view. Thus, reconstructed en face images had a resolution of 34.8 pixels per degree in x-axis and 17.4 pixels per degree. Due to the densely sampled OCT volume dataset, postprocessed customized cross-sectional B-frames through pathologic changes such as an individual microaneurysm or a retinal neovascularization could be imaged.

CONCLUSIONS

Wide-field Megahertz OCT is feasible to successfully image patients with diabetic retinopathy at high scanning rates and a wide angle of view, providing information in all three axes. The Megahertz OCT is a useful tool to screen diabetic patients for diabetic retinopathy.

Photoreceptor inner segment ellipsoid band integrity on spectral domain optical coherence tomography

Spectral domain optical coherence tomography cross-sectional imaging of the macula has conventionally been resolved into four bands. However, some doubts were raised regarding authentication of the existence of these bands. Recently, a number of studies have suggested that the second band appeared to originate from the inner segment ellipsoids of the foveal cone photoreceptors, and therefore the previously called inner segment-outer segment junction is now referred to as inner segment ellipsoidband. Photoreceptor dysfunction may be a significant predictor of visual acuity in a spectrum of surgical and medical retinal diseases. This review aims to provide an overview and summarizes the role of the photoreceptor inner segment ellipsoid band in the management and prognostication of various vitreoretinal diseases.

Intraocular pressure rise is predictive of vision improvement after intravitreal triamcinolone acetonide for diabetic macular oedema: a retrospective analysis of data from a randomised controlled trial

Background

Intravitreal triamcinolone acetonide (IVTA) is an effective treatment for recalcitrant diabetic macular oedema (DMO). It has been shown to improve vision with benefits persisting up to five years. The most common initial side effect of IVTA treatment is rise in intraocular pressure, occurring in approximately 50% of patients within the first 6 months of treatment. We evaluated whether there is a correlation between the development of intraocular pressure rise and improvement in vision.

Methods

Analysis of individual data from 33 eyes of 33 participants treated with IVTA for DMO from a prospective, randomised, double-masked, placebo controlled trial. The degree of intraocular pressure (IOP) rise was correlated with improvement in best-corrected visual acuity (BCVA) at 1 and 6 months.

Results

The proportion of eyes gaining 5 or more logMAR letters was higher in eyes with greater IOP rise (p = 0.044). Better absolute improvement in BCVA at 6 months (p = 0.045) was also found in eyes with greater IOP rise. Regression analyses revealed a correlation between IOP rise of 10 or more mmHg and absolute BCVA improvement at 6 months (odds ratio 1.22, 95% confidence interval 1.01-1.48, p = 0.039), but not at 1 month.

Conclusions

IOP rise and vision improvement appear to be correlated following IVTA for DMO, suggesting that the mechanisms that cause both may be linked.

Trial Registration

Clinical trials.gov NCT00167518, September 5, 2005.

Improvement of visual acuity based on optical coherence tomography patterns following intravitreal bevacizumab treatment in patients with diabetic macular edema

AIM

To report the visual outcome based on various patterns of optical coherence tomography (OCT) morphology in diabetic macular edema (DME), following treatment with anti-VEGF intravitreal bevacizumab (IVB) injection.

METHODS

Sixty-seven consecutive subjects with centre involving DME underwent intravitreal injection of Bevacizumab (1.25 mg/0.05 mL) in this retrospective, comparative, non randomized study. The DME was classified into one of four categories: focal, diffuse, focal cystoid and neurosensory detachment based on OCT. Best corrected visual acuity (BCVA), macular appearance, and OCT findings were used to decide whether the subject should have a repeat injection of intravitreal bevacizumab. Outcome measures were a change in mean BCVA (Snellen converted to logMAR) and central macular thickness (CMT) in each group during the six month follow-up period.

RESULTS

The mean BCVA improved to logMAR 0.23 at final follow-up from a baseline of 0.32 logMAR (P=0.040) in the focal group, logMAR 0.80 at final follow-up from a baseline of 0.82 logMAR (P=0.838) in the diffuse group, worsened to logMAR 0.53 at final follow-up from a baseline of 0.43 logMAR (P=0.276) in the focal cystoid group, and improved to logMAR 0.79 at final follow-up from a baseline of 0.93 logMAR (P=0.490) in the neurosensory detachment group. The mean CMT before treatment were 298.8±25.03 µm in the focal group, 310.8±40.6 µm in the diffuse group, 397.15±31.05 µm in the focal cystoid group and 401.03±75.1 µm in the neurosensory detachment group. A mean of 2.05 (range: 1-5) injections in the focal group, 1.32 (range: 1-2) in the diffuse group, 2.6 (range: 1-6) in the focal cystoid group and 2.6 (range: 1-6) in the neurosensory detachment group were performed during the six month follow-up period. Following intravitreal bevacizumab treatment, vision improved, remained unchanged or worsened in 11, 7 and 2 subjects in focal group; 11, 9 and 8 in diffuse group; 0, 2 and 4 in focal cystoid group and 5, 5 and 3 subjects respectively in neurosensory detachment group.

CONCLUSION

OCT morpholgy patterns in DME may predict the effects of intravitreal bevacizumab treatment, and patients with focal DME are most likely to benefit from the improvent of visual acuity from this treatment.

Association of systemic and ocular risk factors with neurosensory retinal detachment in diabetic macular edema: a case-control study

Background

Diabetic macular edema (DME) with neurosensory retinal detachment (NSD) remains an important cause of visual loss in patients with diabetes. The aim of the study was to elucidate the association of systemic and ocular risk factors with NSD in DME.

Methods

In a retrospective case–control study, we reviewed clinical records of all the subjects with DME seen between January 2010 and December 2010. Cases and controls were selected based on optical coherence tomography and stereoscopic biomicroscopy review. NSD was defined as subfoveal fluid accumulation under detached retina with or without overlying foveal thickening. The association between the presence of NSD, blood pressure, lipid status and various other biochemical parameters was evaluated.

Results

Group I (cases) included 37 eyes of 33 patients having DME with NSD and Group II (controls) included 30 eyes of 21 patients having DME without NSD. Patients ranged in age (mean ± SD) from 50 to 62 years (56.6 +/-6.78) for cases and from 51 to 65 years (58.4+/-7.84) for controls. The duration of diabetes ranged from 4 to 15 year (mean 9.45+/-6.08) among cases and 4 to 14 years (9.7+/-5.12) among controls. Significant risk factors for NSD were high values of systolic and diastolic blood pressure (p = 0.039 and 0.043 respectively).

Conclusion

High systolic and diastolic blood pressures are independent and significant risk factors for NSD in DME.

Foveal morphology affects self-perceived visual function and treatment response in neovascular age-related macular degeneration: a cohort study

Objectives

To investigate the relationship between foveal morphology and self-perceived visual function in patients with neovascular age-related macular degeneration (AMD) and whether foveal characteristics are associated with Ranibizumab treatment response on the self-perceived visual function.

Methods

This prospective cohort study included patients with newly diagnosed neovascular AMD found eligible for treatment with Ranibizumab. Foveal morphology of both eyes was assessed using spectral-domain optical coherence tomography and all patients were interviewed using the 39-item National Eye Institute Visual Function Questionnaire (VFQ). Patients were re-interviewed 3 and 12 months after initiation of treatment with Ranibizumab. We evaluated foveal morphology at baseline in relation to VFQ scores at baseline and clinically meaningful changes in VFQ after 3 and 12 months.

Results

VFQ scores correlated with central foveal thickness, central foveal thickness of neuroretina (CFN), foveal RPE elevation, foveal integrity of the photoreceptor inner segment/outer segment junction (IS/OS), and external limiting membrane. In a multiple linear regression model, only best-corrected visual acuity of the better eye (p<0.001) and the IS/OS status in the better eye (p = 0.012) remained significant (Adjusted R² = 0.418). Lower baseline VFQ and a baseline CFN within 170–270 µm in the better eye were both associated with a clinically meaningful increase in the VFQ scores after 3 and 12 months. An absent foveal IS/OS band in the better eye was associated with a clinically meaningful decrease in the VFQ scores at 12 months.

Conclusions

Foveal morphology in the better eye influences the self-perceived visual function in patients with neovascular AMD and possesses a predictive value for change in the self-perceived visual function at 3 and 12 months after initiation of treatment. These findings may help clinicians provide patients more individualized information of their disease and treatment prognosis from a patient-perceived point-of-view.

Optical coherence tomography in the diagnosis and management of uveitis

Optical coherence tomography (OCT) has become an integral tool in the imaging of numerous diseases of the posterior segment. The diagnostic investigation of infectious and noninfectious uveitic conditions often requires multiple imaging modalities in the appropriate clinical context. Modern OCT technology has proved useful not only in the diagnostic investigation of these conditions, but also in monitoring of their clinical course and therapeutic response. Inflammation-induced changes at the level of the retina, retinal pigment epithelium, and choroid can now easily be identified in these conditions using OCT. Prognostic information on visual acuity outcome can also be estimated based on OCT findings. Numerous OCT findings have been described in the setting of the various uveitides. Although none of these findings appear to be pathognomonic for diagnosis of specific uveitic syndromes, in the appropriate clinical context they can add a great deal of information in the diagnosis and management of uveitis.

The diagnostic function of OCT in diabetic maculopathy

Diabetic maculopathy (DM) is one of the major causes of vision impairment in individuals with diabetes. The traditional approach to diagnosis of DM includes fundus ophthalmoscopy and fluorescein angiography. Although very useful clinically, these methods do not contribute much to the evaluation of retinal morphology and its thickness profile. That is why a new technique called optical coherence tomography (OCT) was utilized to perform cross-sectional imaging of the retina. It facilitates measuring the macular thickening, quantification of diabetic macular oedema, and detecting vitreoretinal traction. Thus, OCT may assist in patient selection with DM who can benefit from treatment, identify what treatment is indicated, guide its implementing, and allow precise monitoring of treatment response. It seems to be the technique of choice for the early detection of macular oedema and for the followup of DM.

Functional and morphological changes in diabetic macular edema over the course of anti-vascular endothelial growth factor treatment

PURPOSE

To evaluate macular morphology and function in diabetic macular edema (DME) over the course of intravitreal anti-vascular endothelial growth factor (VEGF) treatment with Ranibizumab.

METHODS

A consecutive series of 39 study eyes with centre-involving DME were included in this study. In all subjects, best-corrected visual acuity (BCVA) according ETDRS protocol, fluorescein angiography (FA), microperimetric macular sensitivity (MP) and Spectral Domain optical coherence tomography (SD-OCT) cross-sectional scans were obtained before treatment and after 3 monthly applied intravitreal Ranibizumab injections. Six different morphological qualities [IS/OS layer integrity, outer nuclear layer (ONL) cysts, ONL cyst size, inner nuclear layer (INL) cysts, blocking phenomenon and subretinal fluid] were graded of each cross-sectional OCT scan before and over the course of treatment by two experienced graders. Correlation analyses between functional and morphological parameters were obtained.

RESULTS

Mean BCVA increased from 26 ± 14 to 33 ± 13 letters after 3 consecutive monthly applied Ranibizumab injections (p < 0.001). Central retinal thickness (CRT) decreased from 504 ± 144 to 387 ± 122 μm (p < 0.001). Over the course of treatment, IS/OS continuity improved (index: 0.56 ± 0.52 to 0.43 ± 0.49, Z = -1.415, p = 0.157), ONL cyst prevalence and size decreased significantly (index: 0.61 ± 0.44 to 0.56 ± 0.35, Z = -3.41, p = 0.001 and 1.75 ± 0.88 to 1.17 ± 1.05, Z = -4.02, p < 0.001), INL cyst prevalence decreased (index: 0.35 ± 0.52 to 0.28 ± 0.52, Z = -1.60, p = 0.109), blocking phenomenon did not change significantly (index: 00.12 ± 0.16 to 0.13 ± 0.15, Z = -0.45, p = 0.656) and subretinal fluid almost disappeared (index: 0.10 ± 0.24 vs. 0.00 ± 0.01, Z = -2.56, p = 0.011). Correlation analyses revealed highest significant correlations between ONL cyst prevalence and their size and CRT as well as BCVA and MP before treatment and over the course of treatment.

CONCLUSIONS

ONL cysts and their size as morphological parameters correlate with retinal function measured with BCVA and microperimetry before and over the course of anti-VEGF therapy with Ranibizumab in patients with DME.

Structural changes in individual retinal layers in diabetic macular edema

Optical coherence tomography (OCT) has enabled objective measurement of the total retinal thickness in diabetic macular edema (DME). The central retinal thickness is correlated modestly with visual impairment and changes paradoxically after treatments compared to the visual acuity. This suggests the clinical relevance of the central retinal thickness in DME and the presence of other factors that affect visual disturbance. Recent advances in spectral-domain (SD) OCT have provided better delineation of the structural changes and fine lesions in the individual retinal layers. Cystoid spaces in the inner nuclear layer and outer plexiform layer are related to quantitative and qualitative parameters in fluorescein angiography. OCT often shows vitreoretinal interface abnormalities in eyes with sponge-like retinal swelling. Serous retinal detachment is sometimes accompanied by hyperreflective foci in the subretinal fluid, which exacerbates the pathogenesis at the interface of the photoreceptors and retinal pigment epithelium. Photoreceptor damage at the fovea is thought to be represented by disruption of the external limiting membrane or the junction between the inner and outer segment lines and is correlated with visual impairment. Hyperreflective foci in the outer retinal layers on SD-OCT images, another marker of visual disturbance, are associated with foveal photoreceptor damage.

The inner segment/outer segment junction: what have we learnt so far?

PURPOSE OF REVIEW

The advancement of optical coherence tomography has improved the resolution of in-vivo images of the retina. This has led to a wealth of novel knowledge regarding the microstructures of the photoreceptor layer and its relationship with visual functions under different pathological diseases.

RECENT FINDINGS

Identification of the hyperreflective lines in the photoreceptor layer has been made possible by spectral domain optical coherence tomography. The inner segment/outer segment junction, external limiting membrane, cone outer segment tips, and the retinal pigment epithelium were thought to be the origins of the four hyperreflective lines seen in the photoreceptor layer. Integrity of these lines has been linked with visual functions in various retinopathies, and has been suggested to carry prognostic implications. Recovery of initially interrupted lines has been documented following successful treatment.

SUMMARY

Identification of these hyperreflective lines may have clinical implications as visual function was found to correlate closely with their integrity. Restoration of these lines may indicate treatment response and potential visual recovery.

Green-light fundus autofluorescence in diabetic macular edema

AIM

To evaluate the role of central green-light fundus autofluorescence (FAF) in diabetic macular edema (DME).

METHODS

A consecutive series of 92 study eyes with diabetic retinopathy were included. Out of those, 51 diabetic eyes had DME and were compared to 41 diabetic eyes without DME. In all subjects, green-light FAF images were obtained, quantified and classified into various FAF patterns. Cross-sectional optical coherence tomography (OCT) scans were obtained for evaluation of Inner/Outer segment (IS/OS) layer integrity, measurements of central RPE-IS/OS layer thickness as well as classification of DME into various subtypes.

RESULTS

Mean central green-light FAF intensity of eyes with DME (1.289±0.140)log did not significantly differ from diabetic patients without DME (1.317±0.137)log. Most classifiable FAF patterns were seen in patients with cystoid DME. Mean central retinal thickness (CRT) of all study eyes with DME was (501.9±112.4)µm compared to (328.2±27.0)µm in diabetic patients without DME. Patients with DME had significantly more disrupted photoreceptor IS/OS layers than diabetic patients without DME (28/51 vs 5/41, P<0.001). Mean RPE-IS/OS thickness of patients with DME (60.7±14.1)µm was significantly (P<0.001) lower than in diabetic eyes without DME (73.5±9.4)µm. Correlation analys1s revealed non-significant correlations of green-light FAF intensity and OCT parameters in all subtypes of DME.

CONCLUSION

Our results indicate a poor correlation of central green-light FAF intensity with CRT, IS/OS layer integrity or RPE-IS/OS layer thickness in diabetic patients with or without DME and its various subtypes. Thus, central green-light FAF is not suitable for detection of retinal thickening in DME.

Factors associated with visual recovery after sub-Tenon injection of triamcinolone acetonide in diabetic macular edema

Background

The purpose of this retrospective chart review was to evaluate factors associated with improvement of visual acuity after a single sub-Tenon injection of triamcinolone acetonide in patients with diabetic macular edema.

Methods

We reviewed the medical records for 63 consecutive eyes with diabetic macular edema treated by sub-Tenon injection of triamcinolone acetonide and assessed at 2 months postoperatively. We evaluated changes in morphology, foveal photoreceptor status, and parafoveal cystic change, and also measured the central retinal thickness and macular volume. The association of these factors with improvement of vision (logarithm of the minimum angle of resolution, logMAR) was investigated.

Results

Eyes were classified as having cystoid macular edema (CME, n = 52), serous retinal detachment (n = 24), or diffuse diabetic macular edema (n = 4). In eyes with CME, the mean logMAR of visual acuity improved significantly (P = 0.003) from 0.35 ± 0.31 at baseline to 0.29 ± 0.29 after 2 months. However, there was no significant improvement of visual acuity in the eyes with serous retinal detachment or diffuse diabetic macular edema after sub-Tenon injection of triamcinolone acetonide (P = 0.549 and P = 0.545, respectively). The central retinal thickness and macular volume were both reduced significantly after sub-Tenon injection of triamcinolone acetonide in eyes with CME and serous retinal detachment. However, improvement of visual acuity in the eyes with CME was not correlated with the reduction of central retinal thickness or macular volume. Parafoveal cystic changes showed significant improvement after sub-Tenon injection of triamcinolone acetonide in eyes with CME. Photoreceptor status was significantly associated with the visual prognosis in eyes with CME, but not in eyes with serous retinal detachment.

Conclusion

Visual acuity improved significantly after sub-Tenon injection of triamcinolone acetonide without photoreceptor recovery in eyes with CME. Improvement of parafoveal cystic changes in the eyes with CME suggests that bipolar cells or their accessory cells might have displayed functional recovery.