Early choroidal and retinal changes detected by swept-source oct in type 2 diabetes and their association with diabetic kidney disease: a longitudinal prospective study

BACKGROUND

To evaluate structural changes in retina and choroid in patients with type 2 diabetes (T2D) and their association with diabetic kidney disease (DKD).

METHODS

T2D patients with mild or no diabetic retinopathy (DR) were followed for 3 years using structural SS-OCT and OCT angiography (OCT-A) taken every 6 months. Parameters were compared longitudinally and according to the DKD status on baseline.

RESULTS

One hundred and sixty eyes from 80 patients were followed for 3 years, 72 with no DKD (nDKD) at baseline and 88 with DKD. Trend analysis of T2D showed significant thinning in GCL + and circumpapillary retinal fiber neural layer (cRFNL), choroid, and decreased vascular density (VD) in superficial plexus and central choriocapillaris with foveal avascular zone (FAZ) enlargement. Patients with no DKD on baseline presented more significant declines in retinal center and choroidal thickness, increased FAZ and loss of nasal and temporal choriocapillaris volume. In addition, the nDKD group had worse glycemic control and renal parameters at the end of the study.

CONCLUSION

Our data suggests the potential existence of early and progressive neurovascular damage in the retina and choroid of patients with Type 2 Diabetes (T2D) who have either no or mild Diabetic Retinopathy (DR). The progression of neurovascular damage appears to be correlated with parameters related to glycemic control and renal damage.

Optic Nerve Head Changes After Intraocular Pressure-Lowering Glaucoma Surgeries Using Optical Coherence Tomography

PRCIS

Optic nerve head (ONH) changes were detected with swept-source optical coherence tomography (SS-OCT) after intraocular pressure (IOP)-lowering glaucoma surgeries.

PURPOSE

The aim of this study was to detect changes in the ONH with SS-OCT after IOP-lowering procedures.

PATIENTS AND METHODS

Patients with progressing glaucoma who were referred for IOP-lowering procedures were included. The participants underwent a 24-2 visual field test and SS-OCT (DRI OCT Triton Plus; Topcon). IOP and SS-OCT scans were obtained during the preoperative period and up to 7 days and 30-90 days postoperatively. ONH parameters were measured with a B -scan at the center of the optic disc and an average of 5 central B -scans. The hypotenuse of the ONH cup (HOC) was calculated using the Pythagorean theorem: hypotenuse 2 = leg1 2 + leg2 2 , considering the length and depth of the cup as the legs of a right triangle. We also evaluated changes in Bruch membrane opening (BMO)-to-BMO diameter. Statistical analysis was performed using generalized estimating equations.

RESULTS

A total of 15 eyes were included. The mean patient age was 70 (SD, 11.04) years. The mean circumpapillary retinal nerve fiber layer was 60.13 (SD, 23.21) µm and the visual field mean deviation was -13.29 (SD, 8.5) dB. The mean IOP at each visit was: 20.5 (SD, 4.99); 11 (SD, 4.95), and 15.7 (SD, 5.04), respectively. The mean HOC, the mean depth and length of the ONH cup, and the BMO-to-BMO diameter decreased significantly after the IOP-lowering procedures.

CONCLUSIONS

The HOC evaluated with SS-OCT significantly decreased after IOP-lowering surgeries. This parameter was useful for evaluating short-term changes in the ONH.

Early retinal neurovascular findings in post-transplant diabetes mellitus patients without clinical signs of diabetic retinopathy

BACKGROUND

Post-transplant diabetes mellitus (PTDM) is a specific subtype of diabetes with an uncertain impact on mortality and morbidity in post-transplant patients. Diabetic retinopathy is the most common microvascular complication of diabetes mellitus, but the long-term clinical progression in PTDM is unknown. New technologies are being used to assess pre-clinical signs of retinal changes, such as swept-source optical coherence tomography (OCT) and OCT-angiography. The aim of this study was to detect pre-clinical structural and vascular changes in the retina using swept-source-OCT and OCT-angiography in patients with PTDM.

METHODS

In this retrospective cohort study, post-kidney transplant patients were divided into PTDM and non-PTDM (control) groups. Both eyes of eligible PTDM patients and controls were included in this study. Inner retinal layer thickness was measured with swept-source-OCT. Retinal capillary density and the foveal avascular zone were measured with OCT-angiography.

RESULTS

In the PTDM group, reduced thickness was found in the inferior ganglion cell layer plus inner plexiform layer (95% CI -8.76 to -0.68; p = 0.022) and the temporal inferior segment (95% CI -10.23 to -0.76; p = 0.024) of the inner retina, as well as in the retinal nerve fiber layer in the temporal (95% CI -34.78 to -9.28 p = 0.001) and temporal inferior segments (95% CI -33.26 to -5.03 p = 0.008). No significant differences were found in the vascular capillary plexus between groups at all depths, segments, or foveal avascular zone (p = 0.088).

CONCLUSIONS

According to OCT-angiography, PTDM patients had reduced inner neurosensory retinal layers but no significant change in vascular density, which suggests that early neuroretinal degeneration might occur prior to vascular changes secondary to PTDM. Prospective studies could help elucidate the clinical course of retinal neuropathy and microvascular pathology in PTDM and provide a better understanding of PTDM complications.

Organizational intervention to improve access to retinopathy screening for patients with diabetes mellitus: health care service improvement project in a tertiary public hospital

INTRODUCTION

The aim of this study was to improve the access to diabetic retinopathy (DR) screening with retinographies in a tertiary care center through a process conducted by an interdisciplinary group driven by a nurse.

MATERIALS AND METHODS

This is a quality improvement study that evaluated the flow for DR screening conducted by an interdisciplinary group using the Plan-Do-Study-Act methodology. As a result measure, we assessed the quantity of retinographies performed after the project implementation, the proportion of patients who presented abnormal retinographies, and the proportion of patients referred to a specialist.

RESULTS

The new patient screening flow and the reinforcement of available human resources led to an increase in the number of retinographies performed and screened patients. A total of 1184 retinographies were conducted, and it was possible to observe DR alterations in 37.8 % patients, of which only 6 % needed to be referred to the DR reference center.

CONCLUSIONS

This study showed a significant increase in the number of retinographies performed. The Plan-Do-Study-Act methodology was an important tool to improve the flow of patient access to fundus images, helping to consistently and continuously improve these processes.

Early choroidal changes detected by swept-source OCT in type 2 diabetes and their association with diabetic kidney disease

INTRODUCTION

Microvascular changes in eye and kidney shares some common factors in diabetes mellitus (DM). The purpose was to evaluate choroidal thickness (CT) and choriocapillaris (CC) density in patients with type 2 diabetes (T2D) and their association with diabetic kidney disease (DKD) using swept-source optical coherence tomography (SS-OCT).

RESEARCH DESIGN AND METHODS

A cross-sectional study was conducted with patients with T2D with mild or no diabetic retinopathy (DR) and non-diabetic controls. CT was measured with SS-OCT, and CC vascular density was measured with OCT angiography. These parameters were compared with inner retinal layers thickness in patients with and without DKD and non-diabetic controls.

RESULTS

Ninety-three eyes from patients with T2D and 34 eyes from controls volunteers were included. Within the T2D group, 56 eyes with DKD and 37 eyes from patients with no diabetic kidney disease were examined. A statistically significant reduction of CT was observed in patients with DKD compared with controls, with no difference in CC density. There was an association between ganglion cell layer and central choroidal thickness reduction in the DKD group.

CONCLUSIONS

Patients with T2D with DKD showed a decrease in CT with no difference in CC density compared with non-diabetic controls. This thinning might be related to vascular changes of choroidal layers such as Haller's and Sattler's with preservation of CC density, which is crucial for outer retina and retinal pigment epithelium health. Longitudinal studies are warranted to determine the association of choroidal changes with the pathogenesis of diabetes, and its association with early DKD and progression to more severe DR.

Early neurovascular retinal changes detected by swept-source OCT in type 2 diabetes and association with diabetic kidney disease

Purpose

To evaluate retinal thickness and capillary density in patients with type 2 diabetes (T2D) and their association with diabetic kidney disease (DKD) using swept-source optical coherence tomography (SS-OCT).

Methods

A cross-sectional study was conducted with T2D patients with mild or no diabetic retinopathy (DR) and nondiabetic controls. Inner retinal layer thickness was measured with SS-OCT. Retinal capillary density and the foveal avascular zone (FAZ) were measured with SS-OCT angiography (OCTA). SS-OCT parameters were compared in patients with and without diabetic kidney disease (DKD) and nondiabetic controls.

Results

131 DKD eyes showed decreased ganglion cell layer plus (GCL+) (p = 0.005 TI; p = 0.022 I), retinal nerve fiber layer (RNFL) (p = 0.003), and central retinal thickness (CRT) (p = 0.032), as well as foveal avascular zone (FAZ) enlargement (p = 0.003) and lower capillary density in the superficial vascular plexus (p = 0.016, central quadrant), compared to controls. No statistically significant changes were found between diabetic patients without significant DKD and controls.

Conclusion

Our findings suggest early neurovascular damage in patients with T2D; these changes were more significant in patients with DKD. Larger longitudinal studies are warranted to determine the role of early neurovascular damage in the pathophysiology of severe DR.

Health-related quality of life associated with diabetic retinopathy in patients at a public primary care service in southern Brazil

Objective

This study aimed to establish the utility values of different health states associated with diabetic retinopathy in a Brazilian sample to provide input to model-based economic evaluations.

Methods

This cross-sectional study was performed in a sample of patients with type 2 diabetes mellitus (T2D) who underwent teleophthalmology screening at a primary care service from 2014 to 2016. Five diabetic retinopathy health states were defined: absent, non-sight-threatening, sight-threatening, and bilateral blindness. Utility values were estimated using the Brazilian EuroQol five dimensions (EQ-5D) tariffs. Descriptive statistics were calculated. Analysis of covariance was performed to adjust the utility values for potential confounders.

Results

The study included 206 patients. The mean (± standard deviation [SD]) utility value was 0.765 ± 0.19 (95% confidence interval [CI], 0.740-0.790). The adjusted mean utility value was 0.748 (95% CI, 0.698-0.798) in patients without diabetic retinopathy, 0.752 (95% CI, 0.679-0.825) in those with non-sight-threatening state, 0.628 (95% CI, 0.521-0.736) in those with sight-threatening state, and 0.355 (95% CI, 0.105-0.606) in those with bilateral blindness. A significant utility decrement was found between patients without diabetic retinopathy and those with a sight-threatening health state (0.748 vs. 0.628, respectively, p = 0.04).

Conclusion

The findings suggest that a later diabetic retinopathy health state is associated with a decrement in utility value compared with the absence of retinopathy in patients with T2D. The results may be useful as preliminary input to model-based economic evaluations. Further research is needed to investigate the impact of diabetic retinopathy on health-related quality of life in a sample more representative of the Brazilian population.

Swept Source Optical Coherence Tomography Documenting Optic Nerve Involvement in an Aggressive T-Cell Lymphoma

Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of aggressive neoplasms. The involvement of ocular structures in haematological neoplasms is rare and usually associated with central nervous system involvement, which may occur as a result of orbital invasion and optic nerve infiltration. In this case report, we describe ocular findings using the novel swept source optical coherence tomography (SS-OCT) in a case of aggressive T-cell lymphoma. SS-OCT has faster scanning speed, deeper tissue penetration due to its longer wavelength laser of 1050 nm and wider scanning areas. In the present case, SS-OCT was helpful in documenting increased retinal nerve fibre layer thickness and prelaminar protrusion associated with visual loss in a patient with an aggressive T-cell lymphoma.

Individual Macular Layer Evaluation with Spectral Domain Optical Coherence Tomography in Normal and Glaucomatous Eyes

PURPOSE

To evaluate differences in the thickness of the individual macular layers between early, moderate, and severe glaucomatous eyes and compare them with healthy controls.

PATIENTS AND METHODS

Subjects with glaucoma presenting typical optic nerve head findings, high intraocular pressure with or without visual field (VF) damage and normal controls were included. All participants underwent 24-2 perimetry and spectral-domain OCT. Patients were divided into three groups (early, moderate, and severe) based on the mean deviation of the VF and a healthy control group. The device segmented the layers automatically, and their measurements were plotted using the means of the sectors of the inner (3mm) and outer (6mm) circles of the ETDRS grid.

RESULTS

A total of 109 eyes qualified for the study: 14 in the control group and 52, 18 and 25 in the early, moderate and severe groups, respectively. Mean age was 66.13 (SD=12.38). The mean thickness of the circumpapillary retinal nerve fiber layer (RNFL), total macular thickness (TMT), macular RNFL, ganglion cell layer (GCL) and inner plexiform layer (IPL) were significantly different between the 4 groups, with progressive decrease in thickness. Significant overall difference was found for the inner nuclear layer (INL), and the severe glaucoma group presented thicker measurements than controls and early glaucoma. Outer nuclear layer (ONL) was thinner in severe glaucoma group compared with early glaucoma group.

CONCLUSION

Individual macular layer measurement using the inner and outer circles of the ETDRS grid is useful to evaluate different stages of glaucoma. The INL thickening and ONL thinning in advanced glaucoma should be explored in the future studies.

Ophthalmological and Neurologic Manifestations in Pre-clinical and Clinical Phases of Spinocerebellar Ataxia Type 7

Spinocerebellar ataxia type 7 (SCA7) is a polyglutamine disease that progressively affects the cerebellum, brainstem, and retina. SCA7 is quite rare, and insights into biomarkers and pre-clinical phases are still missing. We aimed to describe neurologic and ophthalmological findings observed in symptomatic and pre-symptomatic SCA7 subjects. Several neurologic scales, visual acuity, visual fields obtained by computer perimetry, and macular thickness in optical coherence tomography (mOCT) were measured in symptomatic carriers and at risk relatives. Molecular analysis of the ATXN7 was done blindly in individuals at risk. Thirteen symptomatic carriers, 3 pre-symptomatic subjects, and 5 related controls were enrolled. Symptomatic carriers presented scores significantly different from those of controls in most neurologic and ophthalmological scores. Gradual changes from controls to pre-symptomatic and then to symptomatic carriers were seen in mean (SD) of visual fields - 1.34 (1.15), - 2.81 (1.66). and - 9.56 (7.26); mOCT - 1.11 (2.6), - 3.48 (3.54), and - 7.73 (2.56) Z scores; and "Spinocerebellar Ataxia Functional Index (SCAFI)" - 1.16 (0.28), 0.65 (0.56), and - 0.61 (0.44), respectively. Visual fields and SCAFI were significantly correlated with time to disease onset (pre-symptomatic)/disease duration (symptomatic carriers). Visual fields, mOCT, and SCAFI stood out as candidates for state biomarkers for SCA7 since pre-symptomatic stages of disease.

Microvascular Complications of Posttransplant Diabetes Mellitus in Kidney Transplant Recipients: A Longitudinal Study

OBJECTIVE

To assesses microvascular complications in renal transplant recipients with posttransplant diabetes mellitus (PTDM).

RESEARCH DESIGN AND METHODS

In this observational study, patients with ≥5 years of PTDM were included from a cohort of 895 kidney recipients transplanted from 2000 through 2011. Diabetic retinopathy was evaluated by fundus photographs and optical coherence tomography (OCT). Diabetes kidney disease was evaluated by protein to creatinine ratio (PCR) and estimated glomerular filtration rate (eGFR). Distal polyneuropathy was assessed by Michigan Protocol and 10 g-monofilament feet examinations. The Ewing protocol identified cardiovascular autonomic neuropathy. Renal transplant recipients without PTDM diagnosis (NPTDM) were considered controls.

RESULTS

After 144.5 months of follow-up, 135 (15%) patients developed PTDM, and 64 had a PTDM duration ≥5 years. None of the patients with PTDM presented diabetic retinopathy at fundus photographs, but thinning of inner retinal layers was observed with OCT. More than 60% of patients with PTDM had distal polyneuropathy (OR, 1.55; 95% CI, 1.26 to 1.91; P < 0.001). Cardiovascular reflex tests abnormalities were similar between patients with PTDM and NPTDM (P = 0.26). During the first year and 8.5 ± 3.0 years after renal transplantation, eGFR and PCR did not differ significantly between patients with PTDM or NPTDM.

CONCLUSIONS

This longitudinal study assesses microvascular complications in renal transplant patients with PTDM. A lower than expected prevalence as well as a different clinical course of the complications was observed. PTDM seems to be a unique type of diabetes, and its consequences may be milder than expected in type 1 and type 2 diabetes.

Plasma levels of miR-29b and miR-200b in type 2 diabetic retinopathy

MicroRNAs (miRNAs/miRs) are involved in the pathogenesis of diabetes mellitus and its chronic complications, and their circulating levels have emerged as potential biomarkers for the development and progression of diabetes. However, few studies have examined the expression of miRNAs in diabetic retinopathy (DR) in humans. This case-control study aimed to investigate whether the plasma levels of miR-29b and miR-200b are associated with DR in 186 South Brazilians with type 2 diabetes (91 without DR, 46 with non-proliferative DR and 49 with proliferative DR). We also included 20 healthy blood donors to determine the miRNA expression in the general population. Plasma levels of miR-29b and miR-200b were quantified by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Proliferative DR was inversely associated with plasma levels of miR-29b (unadjusted OR = 0.694, 95% CI: 0.535-0.900, P = 0.006) and miR-200b (unadjusted OR = 0.797, 95% CI: 0.637-0.997, P = 0.047). However, these associations were lost after controlling for demographic and clinical covariates. In addition, patients with type 2 diabetes had lower miR-200b levels than blood donors. Our findings reinforce the importance of addressing the role of circulating miRNAs, including miR-29 and miR-200b, in DR.

Microalbuminuria Is Associated With Early Retinal Neurodegeneration in Patients With Type 2 Diabetes

BACKGROUND AND OBJECTIVE

To evaluate retinal layer changes in patients with type 2 diabetes, microalbuminuria, and no diabetic retinopathy, and to investigate its possible relationship with age, gender, diabetes duration, urinary albumin excretion (UAE), glycosylated hemoglobin, and hypertension.

PATIENTS AND METHODS

A prospective, cross-sectional study was performed in 60 patients divided into three groups: diabetic patients with normal UAE, diabetic patients with microalbuminuria, and controls. Retinal thickness was evaluated by Early Treatment Diabetic Retinopathy Study grid using spectral-domain optical coherence tomography.

RESULTS

The average and sectoral macular thicknesses of the ganglion cell layer (GCL) were significantly thinner in the microalbuminuria group compared to normal UAE group and controls (P < .005). UAE was the only factor related to this reduction in a multiple linear regression analysis.

CONCLUSIONS

The GCL thickness was reduced in eyes in patients with type 2 diabetes and microalbuminuria before clinical signs of diabetic retinopathy. Inner retinal neurodegeneration was independently associated with albuminuria. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:e36-e43.].

Changes in choroidal thickness and volume are related to urinary albumin excretion in type 2 diabetic patients without retinopathy

Purpose

To evaluate choroidal thickness and volume in patients with type 2 diabetes and microalbuminuria using spectral-domain optical coherence tomography.

Methods

We recruited 37 diabetic patients without diabetic retinopathy (18 normoalbuminuric and 19 microalbuminuric) and 21 healthy controls. Choroidal thickness and volume were mapped using the automated Early Treatment Diabetic Retinopathy Study grid and a topographic map of thickness was generated manually. Choroid was also measured at 10 locations under the fovea, temporally and nasally.

Results

Mean choroidal thickness and volume among patients with diabetes and microalbuminuria was reduced in all locations compared to controls (P<0.05). A sectoral decrease of choroidal thickness and volume was shown between microalbuminuric and normoalbuminuric groups.

Conclusion

Choroidal changes were present in type 2 diabetic patients before clinical development of retinopathy. Microalbuminuria was associated with a decrease in choroidal thickness and volume in diabetic patients without diabetic retinopathy.

Macular choroidal thickness in pregnant women with type 1, type 2 and gestational diabetes mellitus measured by spectral-domain optical coherence tomography

Purpose

To analyze choroidal thickness (CT) of pregnant women with type 1 diabetes mellitus (DM), type 2 DM and gestational diabetes mellitus (GDM) using spectral-domain optical coherence tomography.

Patients and methods

This cross-sectional study included 144 eyes of 72 pregnant women in the third trimester divided into four groups: 27 non-diabetic pregnant women; 15 pregnant women with GDM; 16 with type 2 DM and 14 with type 1 DM. CT was measured using optical coherence tomography at ten different locations. We also analyzed possible confounding factors, such as gestational age, glycosylated hemoglobin, time from DM diagnosis, hypertension and severity of diabetic retinopathy.

Results

The comparison between the four groups showed a thinner choroid in patients with type 1 DM in all locations, with statistical significance in subfoveal and temporal measurements. When comparing only patients with type 1 and type 2 DM, adjusting for confounding factors, the choroid of patients with type 1 DM remained thinner at all macular points, also with statistical significance in subfoveal and temporal measurements.

Conclusion

Pregnant women with type 1 DM had significantly thinner CT measurements on subfoveal and temporal locations. No differences were found in CT between the control group and pregnant women with GDM and type 2 DM.

Comparative analysis of choroidal thickness in third trimester pregnant women

Background

The impact of pregnancy on the choroid is still under investigation. The aim of this study is to compare choroidal thickness measurements of healthy pregnant women in the third trimester and healthy non-pregnant women using spectral-domain optical coherence tomography (OCT).

Methods

This cross-sectional study included 122 eyes of 61 women, divided into two groups: 27 healthy pregnant women in the third trimester and 34 age-matched healthy non-pregnant women. Choroidal thickness was measured using Enhanced Depth Imaging OCT at ten different locations: at the fovea and every 500 µm from the fovea up to 2500 µm temporally and up to 2000 µm nasally.

Results

There were no significant differences in the ten measurements of choroidal thickness comparing both groups. Mean subfoveal choroidal thickness was 304.1 + 9.6 µm in the control group and 318.1 + 15.6 µm in the pregnant women group (p = 0.446). There was also no statistically significant association between gestational age and choroidal thickness measurements in the healthy pregnant women group.

Conclusions

Our study showed no statistically difference in choroidal thickness between healthy non-pregnant women and healthy pregnant women in the third trimester.

Novel perspectives on swept-source optical coherence tomography

Technologies for multimodal digital imaging of vitreoretinal diseases have improved the accuracy of diagnosis and the depth of the knowledge of the mechanisms of disease and their response to treatments. Optic coherence tomography (OCT) has become a mandatory tool for the management and for the follow-up of retinal pathologies. OCT technology evolved in the last two decades from time-domain to spectral domain and recently to the swept-source OCTs (SS-OCT). SS-OCT improved the depth of imaging and the scan speed, thus adding novel algorithms and features such as for vitreous and vitreoretinal interface evaluation, choroid segmentation and mapping, OCT angiography and En-face OCT. The multimodal approach using SS-OCT is expected to advance the understanding of retinal pathologies such as age related macular degeneration, diabetic maculopathy, central serous chorioretinopathy, the pachychoroid spectrum and macular telangiectasia. Surgical vitreoretinal diseases such as vitreo-macular traction syndrome, epiretinal membrane, retinal detachment, proliferative vitreoretinal retinopathy and diabetic traction retinal detachment also will be better understood and documented with SS-OCT. This technology also provides great utility for a broad spectrum of ophthalmic pathologies including glaucoma, uveitis, tumors and anterior segment evaluation.

Nondamaging Retinal Laser Therapy: Rationale and Applications to the Macula

PURPOSE

Retinal photocoagulation and nondamaging laser therapy are used for treatment of macular disorders, without understanding of the response mechanism and with no rationale for dosimetry. To establish a proper titration algorithm, we measured the range of tissue response and damage threshold. We then evaluated safety and efficacy of nondamaging retinal therapy (NRT) based on this algorithm for chronic central serous chorioretinopathy (CSCR) and macular telangiectasia (MacTel).

METHODS

Retinal response to laser treatment below damage threshold was assessed in pigmented rabbits by expression of the heat shock protein HSP70 and glial fibrillary acidic protein (GFAP). Energy was adjusted relative to visible titration using the Endpoint Management (EpM) algorithm. In clinical studies, 21 eyes with CSCR and 10 eyes with MacTel were treated at 30% EpM energy with high spot density (0.25-diameter spacing). Visual acuity, retinal and choroidal thickness, and subretinal fluid were monitored for 1 year.

RESULTS

At 25% EpM energy and higher, HSP70 was expressed acutely in RPE, and GFAP upregulation in Müller cells was observed at 1 month. Damage appeared starting at 40% setting. Subretinal fluid resolved completely in 81% and partially in 19% of the CSCR patients, and visual acuity improved by 12 ± 3 letters. Lacunae in the majority of MacTel patients decreased while preserving the retinal thickness, and vision improved by 10 letters.

CONCLUSIONS

Heat shock protein expression in response to hyperthermia helps define the therapeutic window for NRT. Lack of tissue damage enables high-density treatment to boost clinical efficacy, therapy in the fovea, and retreatments to manage chronic diseases.

Restoration of retinal morphology and residual scarring after photocoagulation

PURPOSE

To study healing of retinal laser lesions in patients undergoing PRP using SD-OCT.

METHODS

Moderate, light and barely visible retinal burns were produced in patients with proliferative diabetic retinopathy scheduled for PRP using 100-, 20- and 10-ms pulses of 532-nm laser, with retinal spot sizes of 100, 200 and 400 μm. Lesions were measured with OCT at 1 hr, 1 week, 1, 2, 4, 6, 9 and 12 months. OCT imaging was correlated with histology in a separate study in rabbits.

RESULTS

Lesions produced by the standard 100-ms exposures exhibited steady scarring, with the damage zone stabilized after 2 months. For 400- and 200-μm spots and 100-ms pulses, the residual scar area at 12 months was approximately 50% of the initial lesion size for moderate, light and barely visible burns. In contrast, lesions produced by shorter exposures demonstrated enhanced restoration of the photoreceptor layer, especially in smaller burns. With 20-ms pulses, the damage zone decreased to 32%, 24% and 20% for moderate, light and barely visible burns of 400 μm, respectively, and down to 12% for barely visible burns of 200 μm. In the 100-μm spots, the residual scar area of the moderate 100-ms burns was 41% of the initial lesion, while barely visible 10-ms burns contracted to 6% of the initial size. Histological observations in rabbits were useful for proper interpretation of the damage zone boundaries in OCT.

CONCLUSIONS

Traditional photocoagulation parameters (400 μm, 100 ms and moderate burn) result in a stable scar similar in size to the beam diameter. Restoration of the damaged photoreceptor layer in lighter lesions produced by shorter pulses should allow reducing the common side-effects of photocoagulation such as scotomata and scarring.

Cortical responses elicited by photovoltaic subretinal prostheses exhibit similarities to visually evoked potentials

We have previously developed a wireless photovoltaic retinal prosthesis, in which camera-captured images are projected onto the retina using pulsed near-IR light. Each pixel in the subretinal implant directly converts pulsed light into local electric current to stimulate the nearby inner retinal neurons. Here we report that implants having pixel sizes of 280, 140 and 70 μm implanted in the subretinal space in rats with normal and degenerate retina elicit robust cortical responses upon stimulation with pulsed near-IR light. Implant-induced eVEP has shorter latency than visible light-induced VEP, its amplitude increases with peak irradiance and pulse duration, and decreases with frequency in the range of 2-20 Hz, similar to the visible light response. Modular design of the arrays allows scalability to a large number of pixels, and combined with the ease of implantation, offers a promising approach to restoration of sight in patients blinded by retinal degenerative diseases.

Retinal safety of near-infrared lasers in cataract surgery

Femtosecond lasers have added unprecedented precision and reproducibility to cataract surgery. However, retinal safety limits for the near-infrared lasers employed in surgery are not well quantified. We determined retinal injury thresholds for scanning patterns while considering the effects of reduced blood perfusion from rising intraocular pressure and retinal protection from light scattering on bubbles and tissue fragments produced by laser cutting. We measured retinal damage thresholds of a stationary, 1030-nm, continuous-wave laser with 2.6-mm retinal spot size for 10- and 100-s exposures in rabbits to be 1.35 W (1.26 to 1.42) and 0.78 W (0.73 to 0.83), respectively, and 1.08 W (0.96 to 1.11) and 0.36 W (0.33 to 0.41) when retinal perfusion is blocked. These thresholds were input into a computational model of ocular heating to calculate damage threshold temperatures. By requiring the tissue temperature to remain below the damage threshold temperatures determined in stationary beam experiments, one can calculate conservative damage thresholds for cataract surgery patterns. Light scattering on microbubbles and tissue fragments decreased the transmitted power by 88% within a 12 deg angle, adding a significant margin for retinal safety. These results can be used for assessment of the maximum permissible exposure during laser cataract surgery under various assumptions of blood perfusion, treatment duration, and scanning patterns.

Photovoltaic retinal prosthesis: implant fabrication and performance

The objective of this work is to develop and test a photovoltaic retinal prosthesis for restoring sight to patients blinded by degenerative retinal diseases. A silicon photodiode array for subretinal stimulation has been fabricated by a silicon-integrated-circuit/MEMS process. Each pixel in the two-dimensional array contains three series-connected photodiodes, which photovoltaically convert pulsed near-infrared light into bi-phasic current to stimulate nearby retinal neurons without wired power connections. The device thickness is chosen to be 30 µm to absorb a significant portion of light while still being thin enough for subretinal implantation. Active and return electrodes confine current near each pixel and are sputter coated with iridium oxide to enhance charge injection levels and provide a stable neural interface. Pixels are separated by 5 µm wide trenches to electrically isolate them and to allow nutrient diffusion through the device. Three sizes of pixels (280, 140 and 70 µm) with active electrodes of 80, 40 and 20 µm diameter were fabricated. The turn-on voltages of the one-diode, two-series-connected diode and three-series-connected diode structures are approximately 0.6, 1.2 and 1.8 V, respectively. The measured photo-responsivity per diode at 880 nm wavelength is ∼0.36 A W(-1), at zero voltage bias and scales with the exposed silicon area. For all three pixel sizes, the reverse-bias dark current is sufficiently low (<100 pA) for our application. Pixels of all three sizes reliably elicit retinal responses at safe near-infrared light irradiances, with good acceptance of the photodiode array in the subretinal space. The fabricated device delivers efficient retinal stimulation at safe near-infrared light irradiances without any wired power connections, which greatly simplifies the implantation procedure. Presence of the return electrodes in each pixel helps to localize the current, and thereby improves resolution.

Sympathetic ophthalmia after penetrating keratoplasty: a case report evaluated by spectral-domain optical coherence tomography

BACKGROUND

Sympathetic ophthalmia is a rare, bilateral, diffuse granulomatous uveitis that usually occurs after open globe injury or intraocular surgery. To our knowledge, findings of this condition using spectral-domain optical coherence tomography have not been previously described.

METHODS

Case report.

RESULTS

A case of sympathetic uveitis after a tectonic corneal-scleral keratoplasty because of a fungal keratitis is reported. Spectral-domain optical coherence tomographic images revealed a multilobular serous retinal detachment in the sympathizing eye. The subretinal space was divided by thin septa into compartments filled with subretinal fluid and some high reflective compounds.

CONCLUSION

Spectral-domain optical coherence tomographic imaging noninvasively demonstrated a multilobular serous retinal detachment in the sympathizing eye, sharing the same features previously reported in patients with Vogt-Koyanagi-Harada syndrome.

Randomized clinical trial evaluating mETDRS versus normal or high-density micropulse photocoagulation for diabetic macular edema

PURPOSE

To compare modified Early Treatment Diabetic Retinopathy Study (mETDRS) focal/grid laser photocoagulation with normal-density (ND-SDM) or high-density (HD-SDM) subthreshold diode-laser micropulse photocoagulation for the treatment diabetic macular edema (DME).

METHODS

A prospective, randomized, controlled, double-masked clinical trial with patients with previously untreated DME and best corrected visual acuity (BCVA) worse than 20/40 and better than 20/400. Patients were randomized to receive either mETDRS focal/grid photocoagulation (42 patients), ND-SDM (39 patients), or HD-SDM (42 patients). Before treatment and 1, 3, 6, and 12 months after treatment, all patients underwent ophthalmic examinations, BCVA, color fundus photography, fluorescein angiography, and optical coherence tomography (OCT).

RESULTS

At 12 months, the HD-SDM group had the best improvement in BCVA (0.25 logMAR), followed by the mETDRS group (0.08 logMAR), whereas no improvements were seen in the ND-SDM group (0.03 logMAR). All groups showed statistically significant progressive reduction of central macular thickness (CMT) throughout the study (P < 0.001). The HD-SDM group exhibited the greatest CMT reduction (154 μm), which was not significantly different from that of the mETDRS group (126 μm; P = 0.75).

CONCLUSIONS

At 1 year, the clinical performance of HD-SDM was superior to that of the mETDRS photocoagulation technique, according to the anatomic and functional measures of improvement used in this investigation. A rationale for this treatment modality as a preferable approach is suggested, and the precise role of subthreshold micropulse laser treatment may become more defined as experience grows, guided by optimized treatment guidelines and more comprehensive trials. (Clinicaltrials.gov number, NCT00552435.).

Fundus autofluorescence in patients with blunt ocular trauma

PURPOSE

To report fundus autofluorescence and optical coherence tomography (OCT) findings in patients with blunt ocular trauma.

METHODS

Six eyes of six consecutive patients with blunt ocular trauma were evaluated in an observational case series using colour fundus photography, the Heidelberg Retina Angiograph 2 (HRA2) system for fundus autofluorescence (FAF) and OCT (Stratus OCT).

RESULTS

Three patients presented with secondary retinal pigment epitheliopathy that was identified as a reduced FAF plaque with interposed increased FAF granular smaller lesions. These findings were not as evident in fundus examination and colour photography in two patients. Visual field in one patient showed a decreased area of sensitivity that correlated to the reduced/increased autofluorescent lesion. The other three patients had subretinal haemorrhage and choroidal rupture, which appeared with a reduced FAF with an increased FAF rim after resolution. OCT demonstrated a choriocapillaris/ retinal pigment epithelium (RPE) complex disruption and its resolution over time in all patients with choroidal rupture.

CONCLUSION

Damaged RPE area was more evident and better delineated by FAF imaging compared with fundus examination and fundus photography alone. Autofluorescence imaging might be a useful exam to show the length and severity of post-traumatic retinal lesions and it may add relevant information in the global evaluation of blunt ocular trauma complications. Moreover, OCT added valuable information to the diagnosis and progression of choroidal rupture. Further studies to determine the predictive value of FAF in ocular blunt trauma are warranted.

Controlled transscleral drug delivery formulations to the eye: establishing new concepts and paradigms in ocular anti-inflammatory therapeutics and antibacterial prophylaxis

IMPORTANCE OF THE FIELD

The use of topical agents poses unique and challenging hurdles for drug delivery. Topical steroids effectively control ocular inflammation, but are associated with the well-recognized dilemma of patient compliance. Although administration of topical antimicrobials as prophylaxis is acceptable among ophthalmologists, this common practice has no sound evidence base. Developing a new antimicrobial agent or delivery strategy with enhanced penetration by considering the anatomical and physiological constraints exerted by the barriers of the eye is not a commonly perceived strategy. Exploiting the permeability of the sclera, subconjunctival routes may offer a promising alternative for enhanced drug delivery and tissue targeting.

AREA COVERED IN THIS REVIEW

Ocular drug delivery strategies were reviewed for ocular inflammation and infections clinically adopted for newer class of antimicrobials, which use a multipronged approach to limit risks of endophthalmitis.

WHAT THE READER WILL GAIN

The analysis substantiates a new transscleral drug delivery therapeutic approach for cataract surgery.

TAKE HOME MESSAGE

A new anti-inflammatory and anti-infective paradigm that frees the patient from the nuisance of topical therapeutics is introduced, opening a large investigative avenue for future improved therapies.

Quantitative evaluation of experimental choroidal neovascularization by confocal scanning laser ophthalmoscopy: fluorescein angiogram parallels heparan sulfate proteoglycan expression

The objective of the present study was to develop a quantitative method to evaluate laser-induced choroidal neovascularization (CNV) in a rat model using Heidelberg Retina Angiograph 2 (HRA2) imaging. The expression of two heparan sulfate proteoglycans (HSPG) related to inflammation and angiogenesis was also investigated. CNV lesions were induced with argon laser in 21 heterozygous Zucker rats and after three weeks a fluorescein angiogram and autofluorescence exams were performed using HRA2. The area and greatest linear dimension were measured by two observers not aware of the protocol. Bland-Altman plots showed agreement between the observers, suggesting that the technique was reproducible. After fluorescein angiogram, HSPG (perlecan and syndecan-4) were analyzed by real-time RT-PCR and immunohistochemistry. There was a significant increase in the expression of perlecan and syndecan-4 (P < 0.0001) in retinas bearing CNV lesions compared to control retinas. The expression of these two HSPG increased with increasing CNV area. Immunohistochemistry demonstrated that the rat retina damaged with laser shots presented increased expression of perlecan and syndecan-4. Moreover, we observed that the overexpression occurred in the outer layer of the retina, which is related to choroidal damage. It was possible to develop a standardized quantitative method to evaluate CNV in a rat model using HRA2. In addition, we presented data indicating that the expression of HSPG parallels the area of CNV lesion. The understanding of these events offers opportunities for studies of new therapeutic interventions targeting these HSPG.

Importance of schedule of administration in the therapeutic efficacy of guanosine: early intervention after injury enhances glutamate uptake in model of hypoxia-ischemia

Perinatal cerebral hypoxia-ischemia (HI) is an important cause of mortality and neurological disabilities such as cerebral palsy, epilepsy, and mental retardation. The potential for neuroprotection in HI can be achieved mainly during the recovery period. In previous work, we demonstrated that guanosine (Guo) prevented the decrease of glutamate uptake by hippocampal slices of neonatal rats exposed to a hypoxic-ischemic (HI) insult in vivo when administrated before and after insult. In the present study, we compared the effect of Guo administration only after HI using various protocols. When compared with the control, a decrease of [(3)H] glutamate uptake was avoided only when three doses of Guo were administered immediately, 24 h and 48 h after insult, or at 3 h, 24 h, and 48 h after injury or at 6 h, 24 h, and 48 h after HI. These findings indicate that early Guo administration (until 6 h) after HI, in three doses may enhance glutamate uptake into brain slices after hypoxia/ischemia, probably resulting in decreased excitotoxicity.

Fundus autofluorescence of choroidal nevus and melanoma

BACKGROUND

To describe autofluorescence patterns of choroidal melanocytic lesions using the Heidelberg Retinal Angiograph 2 system (HRA2).

METHODS

20 patients with choroidal melanocytic lesions in the ocular fundus underwent ophthalmologic examination, fundus photography, autofluorescence and optical coherence tomography (OCT). Pathologic examination was performed on one enucleated eye with a large choroidal melanoma.

RESULTS

15 patients had choroidal nevi and 5 had malignant choroidal melanoma (1 small, 1 medium and 3 large tumours). Choroidal nevi did not show any characteristic autofluorescence pattern, although secondary retinal pigment epithelium (RPE) changes, such as drusen and pigment epithelium detachment, appeared faintly hyperautofluorescent in 2 patients. Only the small malignant choroidal melanomas had prominent orange pigmentation, although all melanomas had an intense confluent hyperautofluorescent signal over the lesions. Pathology of one large malignant melanoma revealed lipofuscin underlying RPE.

CONCLUSION

Most nevi did not have characteristic hyperautofluorescent features, but choroidal melanomas seemed to have a pattern of confluent hyperautofluorescence. Therefore, autofluorescence may be a useful non-invasive tool to assess lipofuscin in pigmented choroidal lesions, which may contribute to the diagnosis of malignancy. This hypothesis, however, remains to be confirmed in large prospective studies.

Acquired choroidal folds: a sign of idiopathic intracranial hypertension

BACKGROUND

Choroidal folds may be caused by several underlying ocular and orbital diseases; they are classified as idiopathic when no obvious cause is found. The objective of this study was to determine whether acquired choroidal folds are associated with idiopathic intracranial hypertension.

METHODS

In this observational case series, three patients with normal fundus examination later developed choroidal folds. They underwent complete ocular examination, B-scan ultrasonography, fluorescein angiography, optic coherent tomography (OCT) and magnetic resonance imaging. A neurological consultation, lumbar puncture and measurement of opening pressure of cerebrospinal fluid (CSF) were also obtained for all patients.

RESULTS

Three patients with previously normal ocular fundus developed choroidal folds, and optic nerve subarachnoid space enlargement was seen on B-scan. Clinical and radiological evaluations identified elevation of intracranial pressure, and biochemical analysis of CSF was normal, suggesting a diagnosis of pseudotumour cerebri, which was later confirmed. The first patient developed choroidal folds in one eye first, and 4 years later in the fellow eye. The second patient presented with bilateral optic disk swelling secondary to intracranial hypertension. After treatment, which lowered CSF pressure, bilateral choroidal folds were identified by OCT, fluorescein angiography and ocular fundus photograph. The third patient also developed choroidal folds in one eye, but his fellow eye was difficult to evaluate due to a chorioretinitis scar on the macula. OCT identified choroidal folds in all three patients and in the second patient, it also revealed retinal nerve fiber layer damage.

CONCLUSIONS

Acquired choroidal folds and optic nerve subarachnoid space enlargement may be signs of idiopathic intracranial pressure elevation. Nevertheless, this diagnosis should be confirmed by lumbar puncture. Comprehensive imaging studies should be performed to rule out expanding tumors. The lower CSF pressure in our first two patients suggests that choroidal folds or optic disk swelling may depend on the level of intracranial pressure and may be points in a continuum of clinical presentations.

Hypoxic-ischemic insult decreases glutamate uptake by hippocampal slices from neonatal rats: prevention by guanosine

Brain injury secondary to hypoxic-ischemic disease is the predominant form of damage encountered in the perinatal period. The impact of neonatal hypoxia-ischemia (HI) in 7-day-old pups on the high-affinity [3H] glutamate uptake into hippocampal slices at different times after insult was examined. Immediately following, and 1 day after the insult there was no effect. But at 3 to 5 days after the HI insult, glutamate uptake into the hippocampus was markedly reduced; however, after 30 or 60 days the glutamate uptake into hippocampal slices returned to control levels. Also, this study demonstrated the effect of the nucleoside guanosine (Guo) on the [3H] glutamate uptake in neonatal HI injury, maintaining the [3H] glutamate uptake at control levels when injected before and after insult HI. We conclude that neonatal HI influences glutamate uptake a few days following insult, and that guanosine prevents this action.

Chronic bilateral common carotid artery occlusion: a model for ocular ischemic syndrome in the rat

BACKGROUND

Ocular ischemic syndrome is a devastating eye disease caused by severe carotid artery stenosis. The reduction of blood flow produced by bilateral common carotid artery occlusion (BCCAO) of rats for 7 days induces events related to gliosis with no evident histological damage. However, retinal degeneration and cellular death occur after 90 days of BCCAO. Our purpose has been to investigate the effects of BCCAO for 30 days in the retina of adult rats.

METHODS

Adult Wistar rats were submitted to BCCAO or sham surgery. Both direct and consensual pupillary light reflexes were investigated before and after surgery, everyday for the first week and weekly for 30 days. After 1 month, eyes were enucleated and embedded in paraffin. The retinal ganglion cell (RGC) density and thickness of the internal plexiform (IPL), internal nuclear, outer plexiform, and outer nuclear layers were estimated.

RESULTS

Four rats of the BCCAO group (50%) lost the direct pupillary reflex in both eyes, three rats (37%) lost this reflex in one eye, and only one (13%) maintained it in both eyes. RGC density (cells/mm) was diminished in the BCCAO group, and a significant decrease was found in the total retina and IPL thickness; however, no changes were evident in the other layers. BCCAO pupillary-reflex-negative rats presented with a significant decrease in total retinal thickness and retinal ganglion cell density compared with the sham group. Both BCCAO pupillary-reflex-positive) and -negative rats showed a decrease in IPL compared with the sham group.

CONCLUSION

This study demonstrates that BCCAO for 30 days induces functional and morphological damage to the retina with loss of the pupillary reflex and a decrease in IPL thickness and RGC number. We suggest that this protocol might be used as a model for ocular ischemic syndrome in the rat.

Neonatal hypoxia-ischemia reduces ganglioside, phospholipid and cholesterol contents in the rat hippocampus

Hypoxia-ischemia is a common cause of neonatal brain damage producing serious impact on cerebral maturation. This report demonstrates that rats submitted to hypoxia-ischemia present a marked decrease in hippocampal gangliosides, phospholipids and cholesterol contents as from 7 days after the injury. Although chromatographic profiles of the different ganglioside species (GM1, GD1a, GD1b, and GT1b) from the hippocampus of hypoxic-ischemic hippocampi groups (HI) were apparently unaffected, as compared with controls, there were quantitative absolute reductions in HI. The phospholipid patterns were altered in HI as from the 14th to the 30th day after the injury, where phosphatidylcholine (PC) quantities were higher than phosphatidylethanolamine (PE); additionally, the cardiolipin band was detected only in hippocampi of control adult rats. In general, the absolute quantities of phospholipids were lower in HI than in correspondent controls since 7th day after the injury. Considering that reported effects were maintained, we suggest they express a late biochemical response triggered by the neonatal hypoxic-ischemic episode; the consequences would be cell death and a delay on brain development, expressed by a reduction on synaptogenesis and myelinogenesis processes.

Agmatine induces anxiolysis in the elevated plus maze task in adult rats

Agmatine is an endogenous released polyamine recently proposed to be a putative neurotransmitter, however its physiological role is still to be determined. We investigated the hypothesis that agmatine, systemically administered to adult Wistar rats, might exert anxiolytic-like behavior in the elevated plus maze (EPM) and the open field. Agmatine (1, 10, 20, 40 and 100 mg/kg) and saline were administered i.p. 30 min before the EPM and the open field. Administration of agmatine (20 and 40 mg/kg) increased the time spent in the open arms of the EPM, as compared to the saline group, with no effect on locomotion activity in the open field. However, 100 mg/kg of agmatine significantly reduced the number of entries into enclosed arms of the EPM and the total number of crossings in the open field. We suggest that agmatine, in doses of 20 and 40 mg/kg, causes a mild anxiolytic-like behavior and discuss the possibility that this first reported effect could be caused either by the inhibition of nitric oxide synthase, the blockage of NMDA receptors or by the activation of alpha-2-adrenoceptors.

Agmatine facilitates memory of an inhibitory avoidance task in adult rats

Agmatine is a new putative neurotransmitter; however, the physiological role(s) of this endogenous released polyamine is still to be determined. We investigated its cognitive effect in an inhibitory avoidance task in adult rats. Agmatine (0.1, 1, 10, and 20 mg/kg) or saline was administered ip immediately after training or 1 h before testing. Posttraining injection of agmatine facilitated (p < 0.05) memory consolidation in this task; however pretest treatment showed no effect on retrieval (p > 0.05). We suggest that the facilitatory effect of agmatine on memory consolidation in inhibitory avoidance task might be mediated through the activation of the locus coeruleus.