Evaluation of structural and functional changes in non-pathologic myopic fundus using multifocal electroretinogram and optical coherence tomography

Purpose

To evaluate structural and functional changes in non-pathologic myopic fundus using multifocal electroretinogram (mfERG) and spectral domain-optical coherence tomography (SD-OCT).

Methods

A total of 90 myopic subjects underwent mfERG and SD-OCT. The subjects were divided into four groups according to spherical equivalent refractive error: Group 1 (?0.50 to ?2.75 D), Group 2 (?3.00 to ?5.75 D), Group 3 (?6.00 to ?9.75 D), and Group 4 (?10.0 to ?15.0 D). Total retinal thickness, photoreceptor retinal thickness (PR), outer nuclear retinal thickness and mid-inner retinal thickness (MIR) were measured using SD-OCT in foveola and two perifoveal retinal regions 2.0 mm nasal and temporal from the foveola. The amplitude and implicit time of N1 and P1 mfERG responses were analyzed using six-concentric-ring grouping. Correlations between each retinal thickness, amplitude, and implicit time among the four myopic groups were analyzed.

Results

PR thickness in the foveola and MIR thickness in the perifoveal retina were significantly reduced with increasing myopic refractive errors (p = 0.001, respectively). Significant correlations appeared between N1 amplitude, P1 amplitude, P1 implicit time, and refractive errors (p = 0.001, respectively). Significant correlations appeared between MIR thickness and N1, P1 amplitude (p = 0.001, respectively) as well as N1, P1 implicit time (p = 0.02 and 0.03, respectively) in the perifoveal retina corresponding to ring 4.

Conclusions

The correlation between structural and functional changes in myopia should be considered when interpreting retinal structure and function using SD-OCT and mfERG, especially in high myopia.     

多焦视网膜电图检测糖尿病早期视功能的变化

目的：了解多焦视网膜电图（mfERG）在糖尿病患早期视功能的变化规律。方法：将所有被检分为正常对照组（33例）、糖尿病无视网膜病变组（63例）以及单纯期糖尿病视网膜病变组（43例）。采用mfERG对上述3组进行检测,比较3组mfERG一阶反应N1波与P1波的潜伏期与反应密度。结果：在糖尿病无视网膜病变组中,N1波与P1波反应密度低于正常对照组,异常范围位于环1一环3。其中P。波反应密度在单纯期糖尿病视网膜病变组中进一步降低。N1波与P1波的潜伏期在糖尿病无视网膜病变组中的变化无统计学意义,在糖尿病视网膜病变组中延长,异常范围扩大到环4与环5。结论：mfERG在糖尿病视网膜病变出现之前已发生异常变化,且能够定量地反映随着病情的进展,视功能的损害程度及范围。     

Extrafoveal changes following intravitreal bevacizumab injections for macular edema secondary to branch retinal vein occlusion: an mfERG and OCT study

Purpose

To evaluate the functional and structural changes of extrafoveal macula after intravitreal bevacizumab (IVB) injection in patients with macular edema due to branch retinal vein occlusion (BRVO) using multifocal electroretinogram (mfERG) and optical coherence tomography (OCT).

Methods

A total of 19 eyes of 19 patients with macular edema due to BRVO received three consecutive IVB injections with a 6-week interval. Spectral domain optical coherence tomography (SD-OCT), mfERG, and fluorescein angiography (FA) were performed at baseline. The macular area was divided into four quadrants (Q1–Q4) based on FA. The mean retinal thickness (MRT) and mfERG parameters in each of the four quadrants were measured at baseline and 4 weeks after the third injection.

Results

The MRT in the four quadrants improved significantly after IVB injections (p < 0.01 for Q1 and Q2, p < 0.05 for Q3 and Q4) compared to baseline. The significant improvements in mfERG responses were seen in Q1 and Q2. In Q1, there were 68 and 56 % improvement in N1 and P1 amplitude, respectively (p < 0.01). N1 and P1 amplitude in Q2 increased significantly by 43 and 46 %, respectively, compared to baseline (p < 0.05). The MRT and P1 amplitude were significantly correlated at baseline in Q1 and Q2, but no significant correlations were found after three IVB injections.

Conclusions

The injection of IVB improved functional and structural outcomes in the primarily affected half of the extrafoveal macula effectively. The measurements of structural and functional changes using mfERG and OCT may be appropriate for monitoring the effects of IVB injection in BRVO patients.     

Early local functional changes in the human diabetic retina: a global flash multifocal electroretinogram study

Purpose

To investigate early functional changes of local retinal defects in type II diabetic patients using the global flash multifocal electroretinogram (MOFO mfERG).

Methods

Thirty-eight diabetic patients and 14 age-matched controls were recruited. Nine of the diabetics were free from diabetic retinopathy (DR), while the remainder had mild to moderate non-proliferative diabetic retinopathy. The MOFO mfERG was performed at high (98?%) and low (46?%) contrast levels. MfERG responses were grouped into 35 regions for comparison with DR classification at those locations. Z-scores of the regional mfERG responses were compared across different types of DR defects.

Results

The mfERG waveform consisted of the direct component (DC) and the induced component (IC). Local reduction in DC and IC amplitudes were found in diabetic patients with and without DR. With increasing severity of retinopathy, there was a further deterioration in amplitude of both components. Under MOFO mfERG paradigm, amplitude was a useful screening parameter.

Conclusion

The MOFO mfERG can help in detecting early functional anomalies before the appearance of visible signs, and may assist in monitoring further functional deterioration in diabetic patients.     

Retinal white blood cell flux and systemic blood pressure in patients with type 1 diabetes

Aims

There is evidence that altered retinal blood flow and altered retinal blood flow regulation play a role in the development and progression of diabetic retinopathy. We compared the association between systemic blood pressure and retinal white blood cell flux in patients with type 1 diabetes and healthy control subjects.

Methods

The study was performed in 100 patients with type 1 diabetes with no or minimal diabetic retinopathy and a group of 313 age-matched healthy controls. Inclusion criteria were systolic blood pressure ≤160 mmHg and diastolic blood pressure ≤95 mmHg. None of the subjects took vasoactive medication except insulin. The blue field entoptic technique was used to assess retinal white blood cell flux, velocity and density in the perimacular region. Pressure–flow relationships were calculated for both groups to assess differences in blood flow regulation.

Results

Retinal white blood cell flux was comparable between the two study groups. Both type 1 diabetic patients and healthy subjects showed a significant positive correlation between retinal white blood cell flux and mean arterial pressure (diabetic patients: r?=?0.48; p?<?0.05, healthy subjects r?=?0.28). The correlation coefficients between mean arterial pressure and white blood cell flux were significantly higher in patients with diabetes than in the healthy control group (p?=?0.0459).

Conclusion

Retinal white blood cell flux, as assessed with the blue-field entoptic technique, is not significantly different between type 1 diabetic patients with no or minimal retinopathy and healthy control subjects. Type 1 diabetic subjects do, however, show an abnormal association between systemic blood pressure and retinal white blood cell flux. This indicates altered autoregulation in early diabetic retinopathy.     

Early changes of retinal function in diabetic patients detected by multifocal electroretinogram

To investigate the early changes of retinal function in diabetic patients detected by multifocal electroretinogram (mfERG). ·METHODS: The first-order kernel responses of mfERG were recorded fromeyes of 33 normal control subjects, 63 diabetic patients without retinopathy and 43 diabetic patients with background retinopathy. The response densities and implicit times of N₁ and P₁ were compared among the control, diabetic patients without retinopathy and diabetic patients with retinopathy. ·RESULTS: The response densities of N1 and P1 in central 3 rings were reduced significantly in diabetic eyes with and without retinopathy. And the implicit times of N₁ and P₁ were delayed significantly only in diabetic eyes with retinopathy. ·CONCLUSION: mfERG can detect the early changes of retinal function quantitatively in diabetic patients. Analysis of response densities and implicit times of N₁ and P₁ can reflect the progress of local retinal dysfunction in diabetes     

PFCL and ILM peeling in macular hole with retinal detachment

To investigate the early changes of retinal function in diabetic patients detected by multifocal electroretinogram (mfERG). ·METHODS: The first-order kernel responses of mfERG were recorded fromeyes of 33 normal control subjects, 63 diabetic patients without retinopathy and 43 diabetic patients with background retinopathy. The response densities and implicit times of N₁ and P₁ were compared among the control, diabetic patients without retinopathy and diabetic patients with retinopathy. ·RESULTS: The response densities of N1 and P1 in central 3 rings were reduced significantly in diabetic eyes with and without retinopathy. And the implicit times of N₁ and P₁ were delayed significantly only in diabetic eyes with retinopathy. ·CONCLUSION: mfERG can detect the early changes of retinal function quantitatively in diabetic patients. Analysis of response densities and implicit times of N₁ and P₁ can reflect the progress of local retinal dysfunction in diabetes     

Multifocal electroretinography in subjects with age-related macular degeneration

Purpose

To evaluate retinal function objectively in subjects with different stages of age-related macular degeneration (AMD) using multifocal electroretinography (mfERG) and compare it with age-matched control group.

Methods

A total of 42 subjects with AMD and 37 age-matched healthy control group aged over 55 years were included in this prospective study. mfERG test was performed to all subjects. Average values in concentric ring analysis in four rings (ring 1, from 0° to 5° of eccentricity relative to fixation; ring 2, from 5° to 10°; ring 3, from 10° to 15°; ring 4, over 15°) and in quadrant analysis (superior nasal quadrant, superior temporal quadrant, inferior nasal quadrant and inferior temporal quadrant) were recorded. Test results were evaluated by one-way ANOVA test and independent samples t test.

Results

In mfERG concentric ring analysis, N1 amplitude, P1 amplitude and N2 amplitude were found to be lower and N1 implicit time, P1 implicit time and N2 implicit time were found to be delayed in subjects with AMD compared to control group. In quadrant analysis, N1, P1 and N2 amplitude was lower in all quadrants, whereas N1 implicit time was normal and P1 and N2 implicit times were prolonged in subjects with AMD.

Conclusion

mfERG is a useful test in evaluating retinal function in subjects with AMD. AMD affects both photoreceptors and inner retinal function at late stages.     

糖尿病视网膜1期病变多焦视网膜图变化分析

目的 通过检测糖尿病视网膜1期病变患者多焦视网膜电图(multifocal electroretino-gram,mfERG),评价1期糖尿病视网膜病变患者早期视功能的变化.方法 检测正常对照组31只眼,1期糖尿病视网膜病变组46只眼的mtERG在视野30°的测试范围内6个不同离心度的环形区N1、P1波潜伏期、P1波反应密度改变.结果 在视野30°的测试范围内6个不同离心度的环形区,1期糖尿病视网膜病变组(DR组)与正常对照组之间比较N1、P1波潜伏期显著延长;环1、2区DR组与正常对照组之间比较P1波反应密度显著降低.结论 尚未出现肉眼可见眼底改变的1期糖尿病视网膜病变即可出现视功能的异常,mfERG能够定量的检测1期糖尿病视网膜病变的局部视功能变化,为糖尿病视网膜病变的早期诊断提供有效方法.     

Retinal function in normal and diabetic eyes mapped with the slow flash multifocal electroretinogram

PURPOSE: It has been suggested that late components of the standard multifocal electroretinogram (mfERG) are preferentially affected by diabetes mellitus. The slow-flash (sf-)mfERG stimulates with flashes separated by dark periods, facilitating interpretation of late first-order response components compared with standard multifocal stimulation. Retinal function and response component changes were examined using the sf-mfERG in diabetic subjects with and without diabetic retinopathy. METHODS: Eighteen control subjects, 12 diabetic patients without retinopathy and 17 diabetic patients with nonproliferative diabetic retinopathy (NPDR), were tested monocularly. A total of 103 areas of the central 45 degrees were stimulated by pseudorandom 100-cd/m2 flashes separated by at least 53.3 ms. Major components and the amplitude of the first-order sf-mfERGs were examined. Each subject's N1, P1, and N2 implicit times (ITs) and scalar product amplitudes (SPs) were measured at all 103 retinal locations and converted into z-scores based on the control values. Abnormalities were defined as z-scores greater than 2.33 (P < 0.01). RESULTS: Local functional abnormalities were found in both the diabetic patients with NPDR and in those without retinal disease. In both groups of diabetic patients, most abnormalities occurred more frequently in the inferior retina. Later components (P1 and N2) of the local sf-mfERGs were not preferentially affected by diabetes. The local SP and P1 IT measures distinguished the subject groups better than N1 IT and N2 IT. CONCLUSIONS: Local functional retinal abnormalities in diabetic persons with or without NPDR can be detected and mapped by the sf-mfERG. Diabetes and NPDR do not, however, preferentially affect the late P1 and N2 response components.     

In diabetic eyes, multifocal ERG reflects differences in function between the nasal part and the temporal part of the macula

Purpose

The purpose of the present study was to compare retinal function between the perifoveal nasal and perifoveal temporal areas of diabetic eyes using multifocalERG (mfERG).

Methods

We included 36 eyes from 27 patients with diabetes (age 58?±?14?years; duration of diabetes 13?±?9?years; HbA_1c 7.1?±?1.8%) and a control group with 18 eyes from 18 healthy subjects (age 57?±?11?years). Retinal thickness was assessed with optical coherence tomography (OCT) in the perifoveal areas corresponding to the summed nasal and temporal inner and outer areas. MfERG amplitude and implicit time were recorded from corresponding areas.

Results

Diabetic eyes showed lower mfERG amplitude in the nasal area than in the temporal area (14?±?6 vs 17?±?7?nV/deg²; p?p?=?0.005). In the control group, there were no significant differences between the two areas.

Conclusion

Diabetic eyes showed lower amplitude and longer implicit time in the nasal area than in the temporal, which might indicate that the nasal area is more vulnerable. These findings may be of importance for evaluation of diabetic maculopathy and outcome after laser treatment.     

Single-session photodynamic therapy combined with intravitreal ranibizumab for neovascular age-related macular degeneration: a comprehensive functional retinal assessment

Purpose

To explore functional retinal changes in neovascular AMD patients (nAMD) treated with ranibizumab 0.5 mg combined with photodynamic therapy (PDT) 3 days after the first injection in the long term.

Methods

Patients with no prior treatment for nAMD were treated with 3 injections of ranibizumab 0.5 mg 1 month apart and a single session of standard PDT 3 days after the first injection. Best-corrected visual acuity and time-domain OCT at baseline and every 28 ± 2 days were performed; microperimetry at 3, 6, and 12 months and multifocal electroretinogramm (mfERG) at 3 and 12 months were repeated. Fluorescein angiography and vision-related quality-of-life questionnaire were performed at baseline and 12 months.

Results

12/15 nAMD patients completed the 12 months study and received an average of 3.4 ± 0.7 injections. Mean VA changed from 54.67 ± 15.72 to 59.0 ± 24.77 letters (p = 0.371), while mean retinal sensitivity from 5.5 ± 4.8 to 6.6 ± 6.0 dB (p = 0.216). MfERG N1–P1 response amplitude densities (RADs) were significantly different from baseline (p < 0.01) in the central 0°–2.5°, whereas in the peripheral retinal areas (2.5°–20°), not significant (p > 0.01) changes in N1–P1 RADs were detected. The “general vision” VFQ-25 subscale showed a statistically significant improvement at 3 and 12 months.

Conclusions

Ranibizumab 0.5 mg combined with standard PDT 3 days after the first injection determines an improvement of mfERG values in the retinal central area in nAMD patients in long-term follow-up.     

Comparing three different modes of electroretinography in experimental glaucoma: diagnostic performance and correlation to structure

Purpose

To compare diagnostic performance and structure–function correlations of multifocal electroretinogram (mfERG), full-field flash ERG (ff-ERG) photopic negative response (PhNR) and transient pattern-reversal ERG (PERG) in a non-human primate (NHP) model of experimental glaucoma (EG).

Methods

At baseline and after induction of chronic unilateral IOP elevation, 43 NHP had alternating weekly recordings of retinal nerve fiber layer thickness (RNFLT) by spectral domain OCT (Spectralis) and retinal function by mfERG (7F slow-sequence stimulus, VERIS), ff-ERG (red 0.42 log cd-s/m² flashes on blue 30 scotopic cd/m² background, LKC UTAS-E3000), and PERG (0.8° checks, 99% contrast, 100 cd/m² mean, 5 reversals/s, VERIS). All NHP were followed at least until HRT-confirmed optic nerve head posterior deformation, most to later stages. mfERG responses were filtered into low- and high-frequency components (LFC, HFC, >75 Hz). Peak-to-trough amplitudes of LFC features (N1, P1, N2) and HFC RMS amplitudes were measured and ratios calculated for HFC:P1 and N2:P1. ff-ERG parameters included A-wave (at 10 ms), B-wave (trough-to-peak) and PhNR (baseline-to-trough) amplitudes as well as PhNR:B-wave ratio. PERG parameters included P50 and N95 amplitudes as well as N95:P50 ratio and N95 slope. Diagnostic performance of retinal function parameters was compared using the area under the receiver operating characteristic curve (A-ROC) to discriminate between EG and control eyes. Correlations to RNFLT were compared using Steiger’s test.

Results

Study duration was 15 ± 8 months. At final follow-up, structural damage in EG eyes measured by RNFLT ranged from 9% above baseline (BL) to 58% below BL; 29/43 EG eyes (67%) and 0/43 of the fellow control eyes exhibited significant (>7%) loss of RNFLT from BL. Using raw parameter values, the largest A-ROC findings for mfERG were: HFC (0.82) and HFC:P1 (0.90); for ff-ERG: PhNR (0.90) and PhNR:B-wave (0.88) and for PERG: P50 (0.64) and N95 (0.61). A-ROC increased when data were expressed as % change from BL, but the pattern of results persisted. At 95% specificity, the diagnostic sensitivity of mfERG HFC:P1 ratio was best, followed by PhNR and PERG. The correlation to RNFLT was stronger for mfERG HFC (R = 0.65) than for PhNR (R = 0.59) or PERG N95 (R = 0.36), (p = 0.20, p = 0.0006, respectively). The PhNR flagged a few EG eyes at the final time point that had not been flagged by mfERG HFC or PERG.

Conclusions

Diagnostic performance and structure–function correlation were strongest for mfERG HFC as compared with ff-ERG PhNR or PERG in NHP EG.

     

Electrophysiological studies in newly onset type 2 diabetes without visible vascular retinopathy

The purpose of this study was to investigate the early alterations of retinal function, assessed with electrophysiology, in newly onset type 2 diabetes patients without vascular retinopathy. Seventeen patients with newly diagnosed type 2 diabetes (duration 7±3 months), without any vascular retinopathy in fundus photographs, were examined with full-field electroretinogram (ERG) and multifocal ERG (mfERG). The results were compared with those of age-matched subjects without diabetes. In the dark-adapted full-field ERG, the a-wave and the 30-Hz flicker implicit times were delayed in diabetes patients compared to controls, P=0.001 and P=0.020. In the first-order kernel of the mfERG, the first positive wave, P1, was delayed in all areas measured. The electrophysiological examinations demonstrate early alterations of retinal function characterised by a delayed a-wave implicit time in the dark-adapted full-field ERG, representing the rod signalling, and alterations in the multifocal ERG reflecting cone and/or postreceptoral function.     

Comparison of mfERG waveform components and implicit time measurement techniques for detecting functional change in early diabetic eye disease

This study first compares two methods for measuring first order multifocal electroretinogram (mfERG) implicit time abnormalities in eyes with early diabetic retinopathy. Two analysis methods are used: template stretching (multiplicative scaling) of an 80 msec response epoch and template sliding (cross-correlation or additive scaling) of portions of responses containing the major waveform features. The study also compares the relative sensitivities of N1, P1 and N2 implicit time assessed by cross-correlation. The nature of the change in the mfERG waveform associated with diabetes is also assessed. MfERGs were recorded from 15 eyes of 15 individuals with diabetes and early non-proliferative retinopathy and 20 eyes of 20 healthy control subjects of similar age. Implicit time determined by template stretching is more frequently abnormal in the eyes of the diabetic subjects than the implicit time of any of the components assessed by template sliding. This is attributable to the lower variability of the template stretching implicit time measure in normals. Of the components, P1 is most often abnormal in the eyes of individuals with diabetes. Responses recorded from retinal areas with retinopathic signs are more often abnormal than those from other areas. Later components of the response are not delayed more than earlier ones. We conclude that template stretching is a sensitive measurement technique, but that it does not fully capture the effect of diabetes on the first order mfERG well.     

Improvement of mild retinopathy in type 2 diabetic patients correlates with narrowing of retinal arterioles. A prospective observational study

Purpose

Diabetic retinopathy is one of the leading causes of blindness in the Western world. The disease is characterized by morphological lesions secondary to disturbances in retinal blood flow assumed to be related to disturbances in retinal autoregulation. However, there is a need for elucidating the relation between disturbances in diameter regulation of retinal vessels and the development of diabetic retinopathy in longitudinal studies.

Methods

Sixty-four patients with type 2 diabetes mellitus were subjected to measurement of pressure autoregulation of retinal arterioles using the Dynamic Vessel Analyzer (DVA) and measurement of retinal thickness using OCT scanning, and after a mean of 6.8 years, 42 of the patients were re-examined. The vascular response was compared in patients in whom retinopathy had disappeared, was unchanged, or had worsened.

Results

At baseline, hemoglobin A1c (HbA1c) was significantly higher in the patients who would later experience worsening of diabetic retinopathy than in the other groups, but had been reduced at the follow-up examination. During the follow-up period, the resting diameter of retinal arterioles decreased significantly in the patients who experienced improvement in diabetic retinopathy but was unchanged in the other groups, whereas both the diameter response of retinal arterioles to isometric exercise and retinal thickness increased non-significantly with worsening of retinopathy.

Conclusions

The development of diabetic retinopathy is related to the diameter of retinal arterioles. Future clinical intervention studies should aim at investigating the effects of normalizing arteriolar diameters in diabetic retinopathy.     

The pattern electroretinogram in retinal and optic nerve disease

A retrospective analysis was performed on the transient and steady-state pattern electroretinograms recorded from 42 patients with glaucoma, 13 patients with senile dementia of the Alzheimer's type, 58 patients with diabetes mellitus, and 92 control subjects to evaluate the pattern of electroretinographic changes associated with retinal and optic nerve disease. The amplitudes of both the initial positive component (N1 to P1) and the subsequent negative component (P1 to N2) of the transient (4 rps) responses were measured. From these measurements the (P1 to N2)/(N1 to P1) was derived. The N1 to P1 amplitude of the steady-state pattern electroretinogram also was measured. In the glaucoma patients all three amplitude measures, as well as the amplitude ratio of the components of the transient response, were reduced significantly compared with age-matched controls (p < 0.05). A similar pattern was detected in the patients with Alzheimer's disease, but in this case the only statistically significant amplitude reduction was in the steady-state pattern electroretinogram. A different pattern was observed among the diabetic patients (both with and without retinopathy). Only minor reductions in the amplitude of the transient pattern electroretinogram, which were not statistically significant, were noted. In addition, the ratio of the amplitudes of the components of the transient response did not differ from age-matched controls. The amplitude of the steady-state pattern electroretinogram was reduced in diabetics, but this was significant only for those patients with retinopathy (p < 0.01). These findings support the suggestion that an analysis of both the positive and negative components of the pattern electroretinogram may be useful for differentiating the contributions of retinal and optic nerve dysfunction to visual impairment. The results also indicate that in both retinal and optic nerve disease the steady-state pattern electroretinogram can be an earlier sign of dysfunction than the transient pattern electroretinogram.     

Association between multifocal ERG implicit time delays and adaptation in patients with diabetes

PURPOSE: Local first-order multifocal electroretinogram (mfERG) implicit time (K1-IT) delays have proved to be important and predictive indicators of retinal function in diabetes. To better understand the nature of these delays, the authors examined the spatial association between K1-IT and second-order amplitudes (K2-SNR; a measure of adaptation) in diabetic and control subjects. METHODS: The authors studied K1-IT, K1 amplitude, and K2-SNRs of responses from 35 retinal zones. These were recorded from 20 diabetic patients without retinopathy, 20 patients with mild to moderate nonproliferative diabetic retinopathy (NPDR), and 30 healthy control subjects. The K1-IT and K2-SNR measurements were then adjusted according to normative and subject median values to reduce or remove the effects of retinal location, intersubject differences, and abnormally small K1 amplitudes. RESULTS: There was no significant association between K1-IT and K2-SNR in the control group (P > 0.05) and only a marginal association in the NoRet group (P = 0.05). In contrast, longer K1-ITs were significantly associated with reduced K2-SNRs in NPDR subjects (P < 0.01). In the NPDR eyes, zones without retinopathic lesions showed a significant association between K1-IT and K2-SNR (P < 0.01). CONCLUSIONS: The results suggest that an association between longer K1-IT and reduced K2-SNR (abnormal adaptation) develops after the appearance of NPDR, but this association does not depend on the presence of colocalized retinopathic lesions.     

The multifocal ERG in diabetic patients without retinopathy during euglycemic clamping

PURPOSE: Prolonged multifocal electroretinogram (mfERG) implicit times have been observed in diabetes, although the acute response to hyperglycemia is an acceleration of the ERG. The hypothesis for the current investigation was that this discrepancy is caused by a protracted adaptational response of the retina to hyperglycemia. METHODS: Fourteen patients with type 1 diabetes without retinopathy were blood glucose clamped at 5 mM for 75 minutes before the recording of the mfERG. The results were compared with those found in 14 age-matched healthy subjects. RESULTS: During acute normoglycemia, patients with type 1 diabetes without retinopathy demonstrated an overall 1.36-ms delay of the P1 first-order implicit times (P = 0.0013) and a 0.72-ms delay of the second-order P1 (P = 0.0049) compared with healthy subjects at 4.9 +/- 0.28 mM blood glucose. During acute hyperglycemia, the P1 first-order delay was only 0.81 ms (P = 0.02), and the P1 second-order implicit time was comparable to that of healthy subjects (P > 0.05). The magnitude of the diabetes-associated implicit time delay, at both levels of glycemia, was proportional to the level of chronic hyperglycemia at study entry, as expressed by the patients' HbA1c. CONCLUSIONS: During acute normoglycemia, patients with type 1 diabetes without retinopathy demonstrated a delayed mfERG response compared with the healthy subjects. The delay was more pronounced during euglycemia than during hyperglycemia, and at both levels of glycemia, the delay was proportional to the patients' habitual hyperglycemia. The results show that chronic hyperglycemia induces an adaptational response that tends to normalize retinal implicit times at a higher level of habitual glycemia.     

无视网膜病变的糖尿病患者多焦视网膜电图的变化

目的通过采用多焦视网膜电图（mfERG）对正常对照组、尚未出现视网膜病变的糖尿病患者进行检测，了解mfERG发现糖尿病早期视功能变化的能力。方法采用mfERG进行视功能检测，所有受检者分为33例（33只眼）正常对照组以及63例（63只眼）糖尿病组，其中糖尿病组患者均无视网膜病变。对2组mfERG中N1波与P1波的反应密度与潜伏期进行比较。结果mfERG在糖尿病视网膜病变发生前已有异常，主要表现为环1、环2的P1波反应密度以及环1-环3与环5的N1波反应密度降低。结论mfERG能够在糖尿病视网膜病变出现之前，客观定量地发现早期视功能的变化程度与范围。