Associations Between Outer Retinal Structures and Focal Macular Electroretinograms in Patients With Retinitis Pigmentosa.

Purpose: Our earlier study showed that the width of the intact ellipsoid zone (EZ) of the photoreceptors was significantly but weakly correlated with the amplitudes of the focal macular ERGs (FMERGs). The aim of this study was to determine a microstructure of the photoreceptors in the spectral-domain optical coherence tomographic (SD-OCT) images that was more strongly correlated with the FMERG parameters in eyes with retinitis pigmentosa (RP). Methods: This was a retrospective, observational study. The medical records of 65 patients with RP were reviewed. FMERGs were elicited by a 15-degree stimulus spot. The width of the EZ and the outer segment (OS) area surrounded by EZ and retinal pigment epithelium in the SD-OCT images within 15 degrees of the fovea were evaluated. Spearman correlation tests and multiple stepwise regression analyses were performed. Results: There was a strong correlation between the amplitudes of FMERGs and the EZ width (r = 0.68 for a-wave amplitude; r = 0.64 for b-wave amplitude), and also between the amplitudes of the FMERGs and the OS area (r = 0.69 for a-wave amplitude; r = 0.67 for b-wave amplitude). However, some patients had long EZ widths but had severely reduced FMERGs. Multiple stepwise regression analyses showed that the OS area was the only significant independent predictor of the amplitudes of FMERGs (P < 0.001). Conclusions: The OS area might be a better morphological structure to use to predict the physiological function of the macula.

EVALUATION OF SHORT-TERM OUTCOMES OF INTRAVITREAL AFLIBERCEPT INJECTIONS FOR AGE-RELATED MACULAR DEGENERATION USING FOCAL MACULAR ELECTRORETINOGRAPHY.

PURPOSE: To evaluate the relationship between morphological changes and functional improvements assessed using focal macular electroretinograms after intravitreal aflibercept (IVA) injections in eyes with wet age-related macular degeneration. METHODS: The clinical records of 42 eyes of 42 consecutive patients with naive, wet age-related macular degeneration received 3 monthly IVA were reviewed. The best-corrected visual acuity, central foveal thickness, outer retinal thickness, inner retinal thickness at baseline and 1 month after each IVA, and focal macular electroretinograms at baseline and 1 month after the first and third IVA were compared. RESULTS: Best-corrected visual acuity was improved after the third IVA (P = 0.0091). Central foveal thickness and outer retinal thickness showed decreases after every IVA (P < 0.001, respectively). Inner retinal thickness showed a decrease after the second IVA (P = 0.002), after and third IVA (P = 0.001). On focal macular electroretinograms, a- and b-wave amplitudes showed increases after the third IVA (P = 0.0028, P = 0.0012, respectively). Significant correlations were observed between best-corrected visual acuity and central foveal thickness, a-wave amplitude and outer retinal thickness, and b-wave amplitude and inner retinal thickness changes after the third IVA. CONCLUSION: All parameters significantly recovered after three monthly IVA, with a correlation between functional improvements and morphological changes.

Restoration of Cone Interdigitation Zone Associated With Improvement of Focal Macular ERG After Fovea-Off Rhegmatogenous Retinal Reattachment.

PURPOSE: To determine whether a correlation exists between the parameters of the focal macular ERGs (FMERGs) and the microstructural changes of the photoreceptors after successful surgery for fovea-off rhegmatogenous retinal detachment (RRD). METHODS: Twenty eyes of 20 patients who had undergone successful surgery to reattach the retina in eyes with fovea-off RRD were studied. Focal macular ERGs and spectral-domain OCT (SD-OCT) were recorded at 1 and 6 months after the surgery. Changes of the components of the FMERGs, as well as changes of the SD-OCT parameters including the length of the external limiting membrane (ELM), ellipsoid zone (EZ), cone interdigitation zone (CIZ), and size of the outer photoreceptor area (between ELM and RPE), were determined. RESULTS: During the postoperative period, the mean amplitudes of the a-waves increased by 1.4 times and the b-waves by 1.7 times. Spectral-domain OCT showed that the mean length of the EZ and CIZ and the size of the outer photoreceptor area had increased significantly at 6 months. The degree of the increase in the CIZ and outer photoreceptor area was significantly correlated with the increase in the amplitudes of the b-waves of the FMERGs (r = 0.56, P = 0.042, r = 0.57, P = 0.040, respectively; Spearman rank correlation test). However, the length of the EZ was not significantly correlated with the increase of the b-waves. CONCLUSIONS: A restoration of the EZ alone might not be enough to improve the FMERGs, and a restoration of the EZ accompanied by that of the CIZ was essential for the recovery of the FMERGs after fovea-off RRD.

Flicker electroretinograms before and after intravitreal ranibizumab injection in eyes with central retinal vein occlusion.

PURPOSE: To compare the amplitudes and implicit times of the flicker electroretinograms before and after an intravitreal injection of ranibizumab (IVR) in eyes with a central retinal vein occlusion (CRVO). METHODS: We reviewed the medical records of 15 consecutive patients who had macular oedema secondary to CRVO and had received an IVR at the Nagoya University Hospital from November 2013 to July 2014. Flicker ERGs were recorded with both the RETeval(™) system and a conventional ERG system before the IVR. One month after the IVR, recordings were repeated with only the RETeval(™) system. RESULTS: The mean implicit times of the flicker ERGs of the affected eyes recorded with the RETeval(™) system were significantly longer than that of the fellow eyes (32.2 ± 2.6 msec versus 28.1 ± 1.2 msec, p < 0.001). One month after the IVR, the implicit times of the flicker ERGs of affected eyes were significantly shortened from 32.2 ± 2.6 to 30.6 ± 2.2 msec (p < 0.001). CONCLUSIONS: The shortening of the implicit times of the flicker ERGs after the IVR indicates an improvement of retinal function after anti-VEGF therapy for CRVO eyes.

Electroretinograms and level of aqueous vascular endothelial growth factor in eyes with hemicentral retinal vein occlusion or branch retinal vein occlusion.

PURPOSE: Hemicentral retinal vein occlusion (hCRVO) is a disease related to CRVO but not to branch retinal vein occlusion (BRVO). We reported a significant correlation between aqueous vascular endothelial growth factor (VEGF) levels and the implicit time of 30-Hz flicker electroretinogram (ERG) in CRVO eyes. The purpose of this study was to compare aqueous VEGF levels and ERG components between hCRVO and BRVO eyes. METHODS: The medical records of patients with macular edema secondary to hCRVO (12 eyes) or BRVO (16 eyes) and received an intravitreal injection of bevacizumab (IVB) at the Nagoya University Hospital from July 2009 to May 2013 were reviewed. Full-field ERGs were recorded before the IVB. Aqueous humor was collected just before the IVB to measure VEGF concentration. Differences in aqueous VEGF level and ERG components between hCRVO and BRVO eyes were determined. RESULTS: Mean aqueous VEGF concentration in hCRVO eyes was significantly higher than that in BRVO eyes (504 vs. 148 pg/ml, P < 0.05). The implicit time of 30-Hz flicker ERG was significantly longer in hCRVO than in BRVO eyes (33.5 vs. 29.8 ms, P < 0.01). CONCLUSION: The significant difference in VEGF levels in aqueous and implicit times of 30-Hz flicker ERG suggest that retinal ischemia is more manifest in hCRVO than in BRVO eyes.

Relationship between retinal layer thickness and focal macular electroretinogram components after epiretinal membrane surgery.

PURPOSE: To study the effect of epiretinal membrane (ERM) removal on the function and structure of the retina, and to determine whether the functional changes were correlated with the changes in the thickness of different retinal layers. METHODS: Focal macular electroretinography (FMERG) and spectral-domain optical coherence tomography (SD-OCT) were performed on 17 eyes of 15 patients before and after ERM surgery. The parafoveal retina was divided into an inner layer, a middle layer, and an outer layer in the OCT images. The thickness of each layer was measured before and after the ERM surgery. The a-wave, b-wave, and oscillatory potentials (OPs) of the FMERGs were analyzed before and after the ERM surgery. RESULTS: The thickness of the inner and middle retinal layers was significantly reduced after surgery (by 39% and 23%, respectively). The mean amplitudes of the b-waves and OPs at 6 months postoperatively were significantly larger than those recorded preoperatively (by 21% and 61%, respectively). The ratios of the pre- to postoperative b-wave and OP amplitudes were correlated with the thickness reduction of the middle retinal layer (b-wave, r = -0.51, P < 0.05; OPs, r = -0.82, P < 0.01). CONCLUSIONS: The significant correlations between the reduction in the thickness of the middle retinal layer and increase in the amplitude of the b-waves and OPs suggest that the improvement of macular function after ERM peeling is due to the decrease in the thickness of the middle retinal layer.

Focal macular electroretinograms after intravitreal injections of bevacizumab for age-related macular degeneration.

PURPOSE: To evaluate the changes in the best-corrected visual acuity (BCVA), macular thickness, and focal macular electroretinograms (FMERGs) after three intravitreal injections of bevacizumab for a choroidal neovascularization (CNV) associated with age-related macular degeneration (AMD). METHODS: The medical records of 18 eyes of 18 patients who had received three consecutive monthly intravitreal injections of bevacizumab were retrospectively studied. The BCVA, macular thickness determined by optical coherence tomography (OCT), and FMERGs were measured before the first injection, and 10 days after each of the intravitreal bevacizumab injections. RESULTS: The number of eyes with improvement in BCVA after the first injection was one (6%), after the second injection was four (22%), and after the third injection was five (28%). The number of eyes with reduction in macular thickness was 4 (33%), 8 (44%), and 10 (56%) after each of the three injections. The number of eyes with increase in b-wave amplitude of the FMERGs was 7 (38%), 6 (33%), and 10 (56%) after each of the three each injections. The mean macular thickness was significantly thinner after the first injection, and the mean BCVA was significantly improved after the second injection. The mean amplitude and implicit time of the b-wave of the FMERGs were significantly improved only after the third injection (P<0.05). CONCLUSIONS: All parameters improved but the best was after the third injection, indicating that three monthly intravitreous injections with bevacizumab may be an effective treatment regimen for AMD.

Significant correlation between electroretinogram parameters and ocular vascular endothelial growth factor concentration in central retinal vein occlusion eyes.

PURPOSE: Central retinal vein occlusion (CRVO) leads to retinal ischemia, which then induces an upregulation of vascular endothelial growth factor (VEGF). The aim of this study was to determine whether a significant correlation exists between the ocular VEGF levels and the amplitudes and implicit times of different components of the electroretinogram (ERG) in eyes with a CRVO. METHODS: The medical records of the 20 consecutive patients who had macular edema secondary to CRVO and were examined at the Nagoya University Hospital from November 2008 to February 2010 were reviewed. Because all the patients were scheduled to receive an intravitreal injection of bevacizumab (IVB), it was possible to collect samples of the aqueous humor before the IVB. The correlation between the different components of the ERGs and the VEGF concentration in the aqueous was determined. RESULTS: The mean VEGF concentration of the aqueous humor was 416 pg/mL with a range of 100-1260 pg/mL. The b/a ratio of the single flash ERGs (P = 0.049; ρ = -0.45), implicit times of the cone a-wave (P = 0.028; ρ = 0.50), cone b-wave (P = 0.0059; ρ = 0.63), and 30 Hz flicker ERGs (P = 0.0058; ρ = 0.63) were significantly correlated with the VEGF concentration in the aqueous. CONCLUSIONS: The significant correlations between the different components of the ERGs and the aqueous VEGF concentration indicate that full-field ERGs can be used to detect the CRVO patients at a high risk of developing neovascularization of the iris.

Focal macular electroretinograms after photodynamic therapy combined with intravitreal bevacizumab.

BACKGROUND: Retinal function is transiently depressed after photodynamic therapy (PDT) alone. One of the reasons for this functional impairment is a reduction of choroidal circulation caused by the PDT. The purpose of this study was to determine whether PDT combined with intravitreal bevacizumab (PDT+IVB) can reduce or prevent the transient impaired macular function. In addition, we examined whether a significant correlation existed between the changes in the focal macular electroretinograms (FMERGs), optical coherence tomography (OCT)-determined morphology, and changes in choroidal circulation. METHODS: Thirty-eight eyes that were treated by full fluence PDT+IVB were studied. FMERGs, OCT, and indocyanine green angiography (ICGA) were performed before and after the PDT. The intensity of the diffuse fluorescence within the PDT site was measured by densitometry (I/N ratio). RESULTS: The macula was significantly thinner 1 week after PDT+IVB (P < 0.01). The mean a- and b-wave amplitudes of the FMERGs were not significantly decreased 1 week after PDT+IVB. The mean b-wave amplitudes 3 months after PDT+IVB were significantly increased (P < 0.01). The I/N ratio of ICGA 3 months after PDT+IVB was 0.88 ± 0.1. The correlation between the FMERGs and I/N ratio was not significant. CONCLUSION: The use of IVB with PDT mitigates the reduction of the FMERGs and reduces the macular thickness soon after PDT, regardless of the degree of impairment of choroidal circulation caused by PDT. Finally, the macular retinal function 3 months after PDT+IVB were better than that before the treatment.

Analyses of ERG in a patient with intraocular lymphoma.

PURPOSE: To follow the changes in the electroretinograms (ERGs) in a patient with primary intraocular lymphoma (PIOL) who had a complete remission after chemotherapy. METHODS: ERGs were recorded in a 41-year-old woman with PIOL during and after complete remission with chemotherapy. The patient was diagnosed with PIOL from both the ocular signs and the medical history of cranial lymphoma. RESULTS: The ERGs were depressed in the subject. The amplitudes of the bright white flash b-waves were smaller than the a-waves, resulting in a "negative type" ERG. Six weeks after the beginning of chemotherapy, the ocular changes had resolved, and the ERGs, although not of the "negative type", still showed signs that the amplitude had not returned to normal levels. CONCLUSION: The negative type ERGs indicated that the inner retina had been damaged to a greater extent than the outer retina. In the convalescent stage, when the ocular manifestations were resolved, the ERGs were still not fully recovered. Although only one case was studied, we suggest that ERGs can be used to evaluate and follow patients with a PIOL.

Focal macular electroretinograms after photodynamic therapy combined with posterior juxtascleral triamcinolone acetonide.

PURPOSE: Retinal function is commonly depressed transiently after photodynamic therapy (PDT). Additional treatment may prevent this impaired retinal function. The purpose of this study was to determine the changes in the focal macular electroretinograms (FMERGs) after PDT combined with TA for age-related macular degeneration. METHODS: Thirty-four eyes that were successfully treated by PDT with a posterior juxtascleral injection of TA were studied. FMERGs, optical coherence tomography, and indocyanine green angiography were performed before and after the PDT. RESULTS: The mean amplitudes of the FMERGs were not significantly decreased 1 week after PDT with TA (P > 0.05). The mean ratio of the FMERG b-wave 1 week after PDT to that before PDT was 1.09, with an indistinct hypofluorescence at the site of the PDT (18 eyes), and the ratio was 0.91 in the eyes with a distinct hypofluorescence border (16 eyes; P < 0.05). CONCLUSION: The combined use of TA with PDT mitigated the depression of retinal function soon after PDT. However, there were cases of severe choroidal hypoperfusion corresponding to the site of the laser spot that impaired retinal function in comparison to cases with mild hypoperfusion. Even with severe choroidal hypoperfusion, the deterioration in retinal function was relatively mild, with the b-wave FMERG reduced by only 10%.

Focal macular electroretinograms in eyes with wet-type age-related macular degeneration.

PURPOSE: To study the properties of the focal macular electroretinograms (fmERGs) in eyes with untreated wet-type age-related macular degeneration (AMD). METHODS: fmERGs were recorded from 157 eyes of 157 consecutive patients with untreated wet-type AMD (113 men, 44 women; age, 71.3 +/- 8.0 years). The fmERGs were recorded under direct fundus observation using a modified infrared fundus camera and a 15 degrees stimulus spot. Amplitudes and implicit times of the fmERGs recorded from the AMD patients were compared with those from 21 age-similar healthy controls. RESULTS: The amplitudes of fmERGs in the AMD patients were significantly smaller (P < 0.001) and the implicit times were significantly longer (P < 0.001) than the corresponding values in the control eyes. There was a significant correlation between amplitude and implicit time of the fmERG and visual acuity (logMAR), but the degree of correlation was weak. The difference in the b/a amplitude ratio between the AMD patients and healthy controls was not significant. CONCLUSIONS: The significant reduction in amplitude and the severe delay in implicit times of a- and b-waves of the fmERGs indicated significant functional alterations in the inner and the outer retinal layers of the macular area of eyes with wet-type AMD.

Correlation between macular volume and focal macular electroretinogram in patients with retinitis pigmentosa.

PURPOSE: To determine whether a significant correlation exists between the morphology of the macula measured by optical coherence tomography (OCT) and the amplitude of focal macular electroretinograms (fmERGs) in patients with retinitis pigmentosa (RP). METHODS: fmERGs were recorded in 43 patients with RP and 43 age-similar normal subjects, with a 15 degrees stimulus spot, 5.6 to 5.8 mm in diameter on the fundus. The sum of the volume of the neural retina in the central 6 mm (total macular volume) was measured with the OCT system. The length of the photoreceptor inner segment/outer segment junction (IS/OS line) in a 6-mm diameter macular area was also measured in the OCT images. RESULTS: There was a weak correlation between the total macular volume and the fmERG amplitudes (correlation coefficient, 0.46 for the a-wave and 0.54 for the b-wave). The fmERG amplitudes in the patients with RP with IS/OS line longer than 2 mm were significantly larger than those in patients with RP with IS/OS line shorter than 2 mm, but the correlations between these two factors were weak. One major reason for the low correlations between the macular morphology and fmERGs was that there were some patients with RP who had normal macular volume and long IS/OS line, but had severely reduced focal macular ERGs. CONCLUSIONS: Although the macular volume and length of the IS/OS line correlated weakly with the amplitude of the fmERGs, a preserved macular morphology does not necessarily guarantee normal-amplitude fmERGs in patients with RP.

Comparison of focal macular cone ERGs in complete-type congenital stationary night blindness and APB-treated monkeys.

Focal macular cone electroretinograms (ERGs) and multifocal ERGs were recorded to study the macular function in patients with the complete-type of congenital stationary night blindness (cCSNB). The waveforms of the focal macular cone ERGs and the on- and off-responses of the multifocal ERGs in the cCSNB patients were similar to those recorded from monkey retinas treated with L-2 amino-4-phosphonobutyric acid (APB), suggesting that patients with cCSNB have a complete defect of the on-pathway even in the central retina. The results also demonstrated that there was a paradoxical positive response in the central retina of cCSNB patients, as compared to the negative full-field ERGs in the same subjects.

Preservation of macular oscillatory potentials in eyes of patients with retinitis pigmentosa and normal visual acuity.

PURPOSE: To study the functional changes in the macula of the retina in the early stage of retinitis pigmentosa (RP), by analyzing each component of the focal macular electroretinogram (fmERG). METHODS: fmERGs were recorded from 39 patients with RP with normal visual acuity (>1.0) under direct fundus observation using a modified infrared fundus camera and 5 degrees , 10 degrees , and 15 degrees stimulus spots. The amplitudes and implicit times of the a-wave, b-wave, and oscillatory potentials (OPs) in the patients with RP were compared to those from 30 age-similar normal control subjects. RESULTS: The amplitudes of the different components of the fmERGs in patients with RP ranged from severely reduced to normal. The degree of amplitude reduction increased as the size of the stimulus spot increased in the patients with RP. The relative amplitudes of the OPs (67% of the mean in normal subjects) were better preserved than that of the b-wave (46%) and the a-wave (39%) in a 10 degrees spot in the patients with RP. CONCLUSIONS: The relative preservation of the OPs in the patients with RP could be due to either the buffering effect of the large receptive fields of the OP generators or to the retinal remodeling after the progressive loss of photoreceptors. Recordings of each component of fmERG can provide important information on the different layers of the central retina in RP eyes and can add to the understanding of the pathophysiology of RP.

Correlation between focal macular electroretinograms and angiographic findings after photodynamic therapy.

PURPOSE: It is known that the amplitudes of the multifocal electroretinograms are generally reduced soon after photodynamic therapy (PDT). The purpose of this study was to determine whether this amplitude reduction correlates with the changes in macular thickness or with changes in choroidal circulation. METHODS: Thirty-seven eyes that were successfully treated by PDT were studied. Focal macular electroretinograms (fmERGs) and optical coherence tomography were performed before and 1 week, 1 month, and 3 months after PDT. Indocyanine green angiography was performed before and 3 months after PDT. The indocyanine green angiographic findings were classified into two groups: group A, with indistinct hypofluorescence at the site of the PDT, and group B, with well-defined hypofluorescence borders coinciding with the site of the PDT. RESULTS: The mean amplitudes of the fmERGs were significantly reduced at 1 week after PDT (P < 0.05). The correlations between the changes in the amplitude of the fmERG and the changes in macular thickness were not significant. Sixteen (43%) of the study eyes were classified into group A and 21 (57%) into group B by indocyanine green angiography. The mean ratio of the fmERG b-wave 1 week after PDT to that before PDT was 1.14 +/- 0.62 in group A and 0.65 +/- 0.29 in group B. This difference was statistically significant (P < 0.01). CONCLUSIONS: One of the possibilities that could explain the reduction in the amplitude of the fmERGs soon after PDT is the reduction in choroidal circulation caused by the PDT.

Selective amplitude reduction of the PhNR after macular hole surgery: ganglion cell damage related to ICG-assisted ILM peeling and gas tamponade.

PURPOSE: The photopic negative response (PhNR) is a negative component of the photopic electroretinogram (ERG) that is observed after the b-wave and is thought to originate mainly from the activity of ganglion cells and their axons. The purpose of this study was to determine whether there are subclinical functional changes in the inner retina after macular hole surgery, by recording the PhNR before and after surgery. METHODS: In addition to the routine ophthalmic examinations, photopic ERGs were recorded in 16 eyes with an idiopathic macular hole, before and 3 months after surgery. Photopic ERGs were elicited by white Ganzfeld flashes on a rod-suppressing blue background. The amplitude of the PhNR and the a- and b-waves of the photopic ERGs before and after surgery were compared. PhNRs were also recorded in 14 eyes with epiretinal membrane, before and after surgery. RESULTS: Macular holes were closed and visual acuities were improved without any serious complications in all eyes with a macular hole. The amplitude of the PhNR was significantly reduced after surgery (P < 0.05), whereas the amplitude of the photopic a- and b-waves were not significantly altered. For eyes with an epiretinal membrane, the mean amplitude of the PhNR was slightly decreased after the surgery, but the degree of reduction was only one half of that after macular hole surgery. CONCLUSIONS: These results suggest that there are some functional impairments in the inner retina after macular hole surgery, even though the patients did not show any reduction on subjective visual tests. The PhNR can be a useful clinical test to assess the inner retinal function objectively, before and after vitreoretinal surgery.

Changes in foveal thickness and macular function after transpupillary thermotherapy for age-related macular degeneration.

PURPOSE: To evaluate the effect of transpupillary thermotherapy (TTT) on foveal thickness and macular function in eyes with choroidal neovascularization (CNV) associated with age-related macular degeneration. METHODS: Sixteen eyes with occult CNV and 6 eyes with classic CNV were treated with TTT. Optical coherence tomography and focal macular electroretinograms (FMERGs) elicited by a 15-degree stimulus were performed before, 3 months after TTT in 22 eyes and 6 months after TTT in 18 eyes. RESULTS: Before TTT, the fovea in 20 of the 22 eyes with CNV was significantly thicker than that of normal subjects. The foveal thickness was reduced after TTT in 11 of 14 eyes with occult CNV and remained unchanged in 2 eyes. One eye with occult CNV before TTT developed a classic CNV with significant macular edema and increased foveal thickness 3 months after TTT. The amplitudes of the FMERGs were reduced in all eyes before TTT. In eyes with occult CNV, the mean b-wave amplitude increased significantly after TTT (p = 0.0260 at 3 months, p = 0.0142 at 6 months). When the change of foveal thickness was less than 20% after TTT, all eyes with occult CNV had a 30% or more increase in the b-wave amplitude. In eyes with classic CNV, the mean amplitude of the a- and b-waves did not change significantly after TTT. CONCLUSIONS: TTT improves macular function in eyes with occult CNV associated with age-related macular degeneration more when the change of foveal thickness is slight.

Dynamic aniseikonia measurement: prismatic effect appears on the hess chart.

PURPOSE: To determine if aniseikonia appears on the Hess [Screen] Chart and if it can be measured thereby; and to compare such measurement to the standard Awaya New Aniseikonia Test in both artificial and pathologic aniseikonia. SUBJECTS AND METHODS: Twenty normal subjects with 20% artificial induced aniseikonia (Group 1) and 21 patients with pathologic aniseikonia (Group 2) were examined with the New Aniseikonia Test (NAT) and the Hess Chart. Group 2 was divided into three subgroups: Group 2-1, 13 patients with aphakia, whose operated eyes were more hypermetropic that their better eyes; Group 2-2, 3 patients with myopic anisometropia more than 5 diopters; and Group 2-3, 5 patients who had received macular translocation surgery (MTS). RESULTS: In normals, measurement of the 20% artificial aniseikonia ranged from 10% to 21% (mean 15%) using the NAT, and from 16% to 39% (mean 27.1% vertically and 24.6% horizontally) using the Hess Chart. In the 21 patients with pathologic aniseikonia, the NAT measurements ranged from 0% to 24% (upper limit of the NAT) and the Hess Chart measurements ranged from 0% to 65%. A large amount of the aniseikonia that appeared on the Hess Chart disappeared or was significantly reduced by changing the spectacle correction to a contact lens or intraocular lens. CONCLUSION: The aniseikonia that appeared on the Hess Chart was dynamic aniseikonia, due to rotational magnification inherent and unavoidable in the execution of the aniseikonia measurement on the Hess Chart. Aniseikonia, not due to refractive errors brought on by retinal surgery such as MTS, is difficult to correct with iseikonic lenses or other optical means.