Retinal function determined by flicker ERGs before and soon after intravitreal injection of anti-VEGF agents

Oscillatory potential findings in patients with acute ischaemic central retinal vein occlusion

AIMS

To explore the sensitive components of full-field electroretinography (ERG) as indicators of retina function at the onset of acute ischaemic central retinal vein occlusion (CRVO).

METHODS

11 patients (11 eyes) with ischaemic CRVO and 32 patients (32 eyes) with non-ischaemic CRVO who presented with first-episode unilateral CRVO within 1 month of symptom onset and with no previous intervention were examined by the International Society for Clinical Electrophysiology of Vision standard ERG.

RESULTS

A significant amplitude decline and peak time delay in light-adapted (LA) 3 ERG and LA 30 Hz flicker ERG (p<0.05 for all) was found in the ischaemic CRVO eyes, compared with the non-ischaemic CRVO eyes. The b/a amplitude ratio of dark-adapted (DA) 3 ERG, DA 10 ERG and LA 3 ERG was significantly different between the ischaemic and non-ischaemic groups (p<0.05 for all). Regarding oscillatory potentials (OPs), the amplitudes of OP1, OP2 and OP3 as well as the sum of DA 3 OP1-4 amplitudes (∑OPs) showed significant changes (p<0.01 for all) between two groups. No peak time delay of OPs was found between the ischaemic and non-ischaemic CRVO eyes.

CONCLUSION

The amplitude of DA 0.01 ERG, components of LA 3 ERG and LA 30 Hz flicker ERG, and the b/a amplitude ratio could be among the most sensitive indicators in patients with acute ischaemic CRVO. The amplitudes of OP1, OP2, OP3 and ∑OPs in the CRVO eyes were reduced to 40% of the control values, showing that this quantitative method is reliable for detecting ischaemic retinal diseases, even in early stage.

Electroretinographic Evaluations of Eyes With Endophthalmitis

Purpose

To determine the physiological status of the retina of eyes with endophthalmitis by examining the electroretinograms (ERGs) recorded with a portable recording system and to determine whether the pretreatment ERG findings were correlated with the best-corrected visual acuity (BCVA) after the treatment.

Methods

We examined the medical records of 118 eyes of 108 patients who were diagnosed and treated for infectious endophthalmitis at Saitama Medical University Hospital, Japan, between January 2015 to November 2022. Of these, we studied the 25 eyes of 21 patients who had been evaluated by electroretinography. In bilateral cases, one eye was analyzed. The eyes were classified into those with postoperative endophthalmitis (group S, n = 12) and those with endogenous endophthalmitis (group E, n = 9). Photopic and flicker ERGs were recorded with the RETeval system. The pretreatment clinical factors studied were the ERG components that might be correlated with the post-treatment BCVA.

Results

Eyes in Group E with larger amplitude flicker ERGs (P = 0.0053, ρ = -0.8333) had better BCVA after treatment. In Group S, eyes with larger amplitude flicker ERGs (P = 0.0086, ρ = -0.7173), photopic a-waves (P = 0.0323, ρ = 0.6177), and photopic b-waves (P = 0.0055, ρ = -0.7443) had better BCVA after treatment.

Conclusions

Simple and rapid ERG evaluations under light-adapted condition are helpful in evaluating the pretreatment retinal function and to determine the visual prognosis in eyes with endophthalmitis.

Translational Relevance

Simple and non-time-consuming ERG evaluations are helpful in evaluating the retinal function in eyes with endophthalmitis and predicting the visual prognosis.

Electroretinograms Recorded with Skin Electrodes from Post-Vitrectomy Silicone Oil Filled Eyes with Proliferative Diabetic Retinopathy

Purpose

To determine the physiological status of the retina by electroretinography (ERG) using skin electrodes and the RETevalTM system in eyes that had undergone pars plana vitrectomy (PPV) with silicone oil (SO) tamponade. The vitrectomy was performed for a retinal detachment and proliferative diabetic retinopathy (PDR).

Design

Retrospective case series.

Methods

ERGs were recorded with the RETevalTM system (LKC Technologies Inc. Gaithersburg, MD; Welch Allyn, Inc. Skaneateles Falls, NY) from eight eyes with PDR before and after the SO removal. The amplitudes and implicit times of the a- and b-waves of the ERGs before the SO removal were compared to that after the SO removal.

Results

ERGs were recordable in four eyes before and after the SO removal and the a- and b-amplitudes improved in three eyes and worsened in one eye after the SO removal. In the remaining four eyes, ERGs were non-recordable both before and after the SO removal.

Conclusion

These results indicate that ERGs picked up by skin electrodes can be used to assess the physiology of the retina in eyes with a SO tamponade. The flat ERGs in the SO-filled eye indicated the presence of diffuse retinal damage which was confirmed by the flat ERGs after the SO removal.

Electroretinographic Evaluations Using Skin Electrode of Eyes with Bleb-Related Endophthalmitis Following Vitrectomy with 0.025% Povidone Iodine Irrigation

Purpose

To determine whether 0.025% povidone-iodine (0.025% PI) in the irrigation solution during vitrectomy for endophthalmitis is safe.

Methods

Two cases of bleb-associated endophthalmitis were treated with vitrectomy using 0.025% PI in the irrigation solution. The RETevel electroretinographic (ERG) system with skin electrodes was used to assess the physiology of the retina pre- and postoperatively.

Case

Case 1 was a 46-year-old man who had atopic keratoconjunctivitis and underwent trabeculectomy with the creation of a bleb after there was a rise in the intraocular pressure. One month postoperatively, a mild filtering bleb-associated endophthalmitis developed, and the eye was treated with intravitreal and subconjunctival injections of vancomycin (VCM) and ceftazidime (CAZ). After three days, the fundus was not visible and B-mode echography showed an area of high brightness in the retina. Vitrectomy with irrigation with VCM and CAZ, and 0.025% PI was performed successfully. Pre- and postoperative ERGs showed an improvement in both the a- and b-wave amplitudes and the b/a ratio was stable at 2.0. Case 2 was a 63-year-old man who had undergone trabeculectomy for glaucoma. Five years later, the eye developed blebitis which was treated with topical and subconjunctival injections of VCM and CAZ. Three days later, vitreous opacities appeared and a high brightness area was seen in the B-mode echographic images. Vitrectomy with VCM and CAZ, and 0.025% PI irrigation was successfully performed. Comparisons of the pre- and postoperative ERGs found that the a- and b- wave amplitudes of the ERGs increased and the b/a ratio was stable at approximately 1.5.

Conclusion

Vitrectomy with 0.025% PI irrigation is safe and ERG recordings with skin electrodes can be used to evaluate the pre- and postoperative retinal physiology safely.

Early changes in photopic negative response in eyes with glaucoma with and without choroidal detachment after filtration surgery

BACKGROUND/AIMS

To evaluate the electroretinographic (ERG) changes in the early postoperative period following glaucoma filtration surgery, and its relationship with choroidal detachment (CD).

METHODS

This retrospective observational single-centre study included 57 consecutive patients with primary open-angle glaucoma who underwent unilateral glaucoma filtration surgery. The patients were divided into two groups according to the presence or absence of CD. ERG components, including the photopic negative response (PhNR), a-wave and b-wave were compared before and after surgery using skin electrodes.

RESULTS

There were 46 patients in the non-CD group and 11 in the CD group. ERG was recorded within 5.1 (2.1 to 8.1) (mean (95% CI)) days after surgery. In the non-CD group, the PhNR amplitude, PhNR/b-wave amplitude ratio and PhNR implicit time improved significantly after surgery (p=0.008, 0.002 and 0.039, respectively). In the CD group, the amplitude of the PhNR, a-wave and b-wave were significantly deteriorated after surgery (p=0.002, 0.001 and 0.001, respectively). Postoperative intraocular pressure (IOP) (p=0.031) and postoperative CD (p<0.001) were significantly associated with change in the PhNR amplitude in the univariate models. In the multivariate analysis, severe CD (stage 3) cases tended to be deteriorated more.

CONCLUSION

Even in the early postoperative period within several days, the PhNR amplitude increased with IOP lowering following filtration surgery in the absence of CD. The presence of CD may arrest the improvement of the retinal ganglion cell function. The present results enhance understanding the structural and functional recovery after glaucoma surgery and the role of postoperative CD.

Electrophysiological Evaluation of Macular Photoreceptor Functions in Patients with Choroidal Neovascular Membranes

PURPOSE

To evaluate changes in cone functions using light-adapted (LA) 30 Hz flicker and LA 3.0 electroretinography (ERG) in intravitreal ranibizumab (IVR)-treated naïve neovascular age-related macular degeneration (nAMD) patients.

MATERIALS AND METHODS

This retrospective interventional study reviewed the medical records of 32 nAMD patients (32 eyes) who received monthly IVR between January 2019 and January 2021. A comprehensive ophthalmic examination, including best-corrected visual acuity (BCVA) testing and slit-lamp biomicroscopy, was performed as part of their clinical care, followed by LA 30 Hz flicker and LA 3.0 ERGs, optical coherence tomography, and fundus fluorescein angiography. All measurements were taken before IVR (baseline), as well as at months 6 and 12 later. Treatment was resumed for up to 12 months if recurrence occurred.

RESULTS

Compared to baseline, visual acuity improved significantly at months 6 and 12, respectively, coinciding with a significant decrease in central macular thickness (p < 0.05 for all). LA 30 Hz flicker ERG b-wave amplitude decreased significantly between baseline and months 6 and 12, respectively (p < 0.05 for both). There were no significant changes in LA 3.0 ERG a- and b-wave amplitudes between baseline and month 6 (p > 0.05 for both), but a significant decrease existed between baseline and month 12 (p < 0.05 for both). While LA 3.0 ERG a-wave implicit time increased significantly (p < 0.05 for both) between baseline and months 6 and 12, respectively, b-wave implicit time did not (p > 0.05 for both). Also, LA 30 Hz flicker ERG b-wave implicit times did not differ significantly between baseline and months 6 and 12, respectively (p > 0.05, for both).

CONCLUSIONS

IVR was associated with long-term electrophysiological changes in cone functions, as measured by LA 30 Hz flicker and LA 3.0 ERGs.

Effects of recording sequence on flicker electroretinographics recorded with natural pupils corrected for pupil area

BACKGROUND

A new handheld electroretinographic (ERG) recording system can record ERGs without mydriasis. However, this RETeval system cannot record ERGs from both eyes simultaneously. Thus, the purpose of this study was to determine whether the sequence of the ERG recordings will alter the results.

METHODS

We studied 30 eyes of 30 healthy subjects. The flicker ERGs were recorded with the RETeval system without mydriasis and were elicited by 8, 16 and 32 photopic Td-s. The flicker ERGs were recorded at two sessions. Session 1, the ERGs were recorded from the right eye and then the left eye, and Session 2, ERGs were recorded from the left eye then the right eye. We compared the implicit times, amplitudes and pupil diameters of the right eye between these two sessions.

RESULTS

The implicit time of the flicker ERGs was significantly shorter (p < 0.001), and the pupil diameters were significantly smaller (p = 0.013) at Session 2 than Session 1 but only for the lower stimulus intensity of eight Td-s. There was a significant correlation of the differences in the implicit times and the differences in the pupil diameter between the two sessions (r = 0.406, p = 0.026).

CONCLUSIONS

The results indicate that the implicit times of the fundamental components of RETeval flicker ERGs can be affected by the sequence of recordings for lower stimulus intensities. This was most likely due to the differences of the pupil diameter during the recordings. We recommend that stronger stimuli be used to record the RETeval flicker ERGs to minimize the effects of the sequence of recordings.

An inadvertent issue of human retina exposure to endocrine disrupting chemicals: A safety assessment

Endocrine disrupting chemicals (EDCs) are a group of chemical compounds that present a considerable public health problem due to their pervasiveness and associations with chronic diseases. EDCs can interrupt the endocrine system and interfere with hormone homeostasis, leading to abnormalities in human physiology. Much attention has been focused on the adverse effects EDCs have on the reproductive system, neurogenesis, neuroendocrine system, and thyroid dysfunction. The eye is usually directly exposed to the surrounding environment; however, the influences of EDCs on the eye have received comparatively little attention. Ocular diseases, such as ocular surface diseases and retinal diseases, have been implicated in hormone deficiency or excess. Epidemiologic studies have shown that EDC exposure not only causes ocular surface disorders, such as dry eye, but also associates with visual deficits and retinopathy. EDCs can pass through the human blood-retinal barrier and enter the neural retina, and can then accumulate in the retina. The retina is an embryologic extension of the central nervous system, and is extremely sensitive and vulnerable to EDCs that could be passed across the placenta during critical periods of retinal development. Subtle alterations in the retinal development process usually result in profound immediate, long-term, and delayed effects late in life. This review, based on extensive literature survey, briefly summarizes the current knowledge about the impact of representative manufactured EDCs on retinal toxicity, including retinal structure alterations and dysfunction. We also highlight the potential mechanism of action of EDCs on the retina, and the predictive retinal models of EDC exposure.

Effects of Intravitreal Aflibercept on Retinal Function and Improvement of Macular Edema Associated With Diabetic Retinopathy

Purpose

To determine the effectiveness of intravitreal aflibercept (IVA) on the retinal function in eyes with diabetic macular edema (DME).

Methods

Twenty-five eyes of 25 patients with DME were treated with three consecutive monthly IVA injections. The retinal sensitivities (RS) within the central 10° were determined by microperimetry (MP). The central subfield macular thickness (CMT) was determined by optical coherence tomography, and the implicit times (IT) and amplitudes (Amp) of the flicker electroretinograms (ERGs) were determined from the ERGs elicited and recorded by the RETeval. The number of microaneurysms (MAs) was counted in the fundus photographs. The assessments were made before the IVA injections (pre-IVA) and one week after the IVA injections (post-IVA). The correlations between the reduction ratio of the MA numbers/CMT and RS/IT/Amp were evaluated.

Results

The mean RS improved from 19.9 ± 5.9 dB to 22.0 ± 5.8dB, the CMT decreased from 485.7 ± 90.6 µm to 376.9 ± 81.6 µm, and the number of MAs decreased from 49.6 ± 33.2 to 24.8 ± 18.1 after the IVA injection (all P < 0.01). The changes in the IT from 31.3 ± 3.3 ms to 31.5 ± 3.1 ms and the Amp from 12.2 ± 5.5 µV to 11.3 ± 6.1µV post-IVA were not significant. A significant correlation was found between the relative changes in the CMT and RS (r = −0.43; P = 0.02), the MAs and RS (r = −0.38; P = 0.03). No significant correlation was observed between the relative changes of the number of MAs/CMT and IT/Amp.

Conclusions

IVA can improve both central retinal function and anatomical conformation.

Translational Relevance

A new aspect of aflibercept will be useful for DME treatment.