ARCUATE NERVE FIBER LAYER CHANGES AFTER INTERNAL LIMITING MEMBRANE PEELING IN IDIOPATHIC EPIRETINAL MEMBRANE.

PURPOSE: To analyze the relationship between swelling of the arcuate nerve fiber layer (SANFL) and long-term decrease of retinal nerve fiber layer thickness after internal limiting membrane peeling for idiopathic epiretinal membrane, and to investigate if SANFL is related to a mechanical surgical damage. METHODS: Prospective, interventional consecutive case series of 46 eyes that underwent combined epiretinal membrane/internal limiting membrane peeling for idiopathic epiretinal membrane. Infrared, blue autofluorescence, color fundus imaging and measurement of retinal nerve fiber layer thickness in six peripapillary sectors by spectral-domain optical coherence tomography were performed preoperatively and at 2 weeks, 1, 3, 6, and 12 months after surgery. The presence of SANFL was checked postoperatively on infrared and blue autofluorescence fundus imaging, and the extent of each SANFL was measured on infrared fundus images. RESULTS: Areas of SANFL were identified in 39 eyes (84.8%) at 2-week follow-up. Retinal nerve fiber layer thickness significantly decreased in the temporal sectors at 1, 6, and 12 months (P < 0.0001). The linear extent of SANFL was significantly correlated with the percentage of reduction in retinal nerve fiber layer thickness in the temporal (R = 0.45; P < 0.0001) and infero-temporal (R = 0.23; P = 0.0008) sectors at 12 months of follow-up. Correspondence between sites of surgical grasping and the points of origin of SANFL was demonstrated on blue autofluorescence fundus images superimposed on intraoperative surgical frames. CONCLUSION: Early postoperative SANFL is correlated with late focal retinal nerve fiber layer thinning in the temporal sectors. Intraoperative surgical grasping seems to be a leading factor for the onset of SANFL.

Early impairment of the full-field photopic negative response in patients with Stargardt disease and pathogenic variants of the ABCA4 gene.

BACKGROUND: To study the photopic negative response of the full-field photopic electroretinography (ERG) in Stargardt patients with pathogenic variants in the ABCA4 gene. METHODS: A retrospective analysis of 35 Stargardt patients with ABCA4 gene pathogenic variants, compared to normal age-matched controls. Patients were clinically followed at the Ophthalmology Department of Fondazione Policlinico Universitario A. Gemelli/Università Cattolica del Sacro Cuore, Rome, Italy. RESULTS: The photopic negative response of the full-field photopic ERG was compromised in most Stargardt patients. In the presence of a normal B-wave, the amplitude ratio between the photopic negative response and the B-wave displayed a 97% accuracy in detecting diseased eyes (receiver operating characteristic curves). CONCLUSIONS: In Stargardt patients with ABCA4 pathogenic mutations, the photopic negative response of the full-field photopic ERG is a very sensitive disease read-out. Its inclusion in standard ERG analysis would be a no-cost addition of practical consequence in the follow-up of Stargardt disease. The early impairment of the photopic negative response suggests that inner retinal function might be affected in Stargardt disease earlier than previously acknowledged.

NGF eye-drops topical administration in patients with retinitis pigmentosa, a pilot study.

BACKGROUND: Preclinical trials have shown beneficial effects of nerve growth factor (NGF) administration on visual function in animal models of retinitis pigmentosa (RP). The aim of this pilot study was to explore the potential efficacy of short term NGF eye drops treatment in patients affected by RP. METHODS: The trial consisted in 10 days daily administration of murine NGF as eye-drops for a total dose of 1 mg NGF/pt. Eight RP patients at an advanced stage of the disease were included in the trial. To monitor safety and potential adverse effects subjects underwent standard clinical measures and were requested to report any general or topic alterations following NGF assumption. Retinal function was assessed at baseline and after treatment by best-corrected visual acuity measurement (BCVA), macular focal electroretinogram (fERG) recording and Goldmann visual field testing. RESULTS: A transient tolerable local corneal irritation was the only adverse effect reported. fERG and BCVA remained within the limits determined by test-retest analysis of a large cohort of RP patients. Three patients reported a subjective feeling of improved visual performance. This was associated to a temporary enlargement of the visual field in all three patients and to improved fERG in two of the three. CONCLUSIONS: Short-term administration of NGF eye-drops caused neither significant adverse effects nor visual function losses in the tested RP patients. A minority of patients experienced an improvement of visual performance as shown by Goldmann visual field and fERG. This study supports the safety and possible efficacy of NGF eye-drops administration in RP patients. TRIAL REGISTRATION: EudraCT n. 2008-004561-26.

25-Gauge Pars Plana Vitrectomy for Retained Lens Fragments in Complicated Cataract Surgery.

PURPOSE: To verify the efficacy of 25-gauge pars plana vitrectomy (PPV) for the management of posteriorly dislocated lens material after complicated cataract extraction and to determine in what patients this approach offers the optimal benefit in terms of efficacy and safety, considering the amount of retained nuclear material and the duration of surgery. METHODS: Forty eyes of 40 patients with retained lens fragments undergoing early (within 1 week) or late (within >1 week) 25-gauge PPV were retrospectively reviewed. The amount of dislocated nuclear material was graded by the surgeon intraoperatively, and the patients were divided into two groups according to the nuclear grading: group A (≤50% dropped nucleus) and group B (>50% dropped nucleus). The presence of brunescent nuclear pieces was considered. The outcomes measured included best-corrected visual acuity (BCVA) and postoperative complications such as retinal detachment, cystoid macular edema (CME) and postoperative ocular hypertension or hypotonia. RESULTS: The patients had a mean age of 78 years. The mean preoperative logarithm of the minimum angle of resolution (logMAR) BCVA was 0.57 ± 0.24 (20/80). A significant positive correlation was found between nuclear material grade and PPV duration (R2 = 0.81, p < 0.0001). None of the patients had dislocation of brunescent nuclear pieces. On postoperative day 1, the mean postoperative intraocular pressure was 16.75 ± 2.7 mm Hg, with no case of ocular hypotonia. At 6 months of follow-up, the mean logMAR BCVA improved to 0.23 ± 0.3 (20/32). Retinal detachment developed in 4 patients (10%), occurring only in patients of group B (p < 0.002). Four patients with late PPV developed postoperative CME, with no case of CME among patients with early vitrectomy (p = 0.014). CONCLUSION: Removal of dislocated lens fragments after complicated cataract surgery can be effectively managed with 25-gauge PPV, although it appears to be most efficient for cases with a limited amount of dislocated lens material. In consideration of the higher rate of retinal detachment observed in cases of prolonged PPV time, the expected duration of surgery should be taken into account when choosing the best surgical approach. Visual outcomes are not affected by the timing of PPV, whereas early vitrectomy seems to prevent the onset of inflammatory macular edema.

A case of malignant glaucoma following insertion of Preserflo™ MicroShunt.

PURPOSE: To describe a case of malignant glaucoma following insertion of a Preserflo™ MicroShunt in a patient with primary open angle glaucoma (POAG). DESIGN: Case report. CASE: A 46-year-old Caucasian man with medically uncontrolled POAG developed malignant glaucoma 1 day after an uncomplicated insertion of a mitomycin C (MMC) augmented Preserflo MicroShunt (PMS). RESULTS: Initial medical treatment with aqueous suppressants and atropine 1% resulted in temporary resolution of the episode, although partial occlusion of the PMS with iris required a Nd:YAG laser iridotomy to open the inlet of the device. However, the malignant glaucoma recurred 6 days later. Temporary resolution was subsequently achieved with an Nd:YAG laser peripheral irido-zonulo-hyaloidotomy in combination with topical atropine, though a subsequent PMS revision was required due to bleb encapsulation. Unfortunately, the revision procedure was followed 2 days later, by a further recurrence of malignant glaucoma which was eventually resolved by left pars plana vitrectomy (PPV) in combination with clear lens extraction (CLE) and surgical irido-zonulo-hyaloidectomy. Subsequently, the eye remained stable, with a deep anterior chamber (AC), a partially functioning bleb, and an intraocular pressure (IOP) of 14 mmHg on one topical IOP-lowering agent, 8 months after the last procedure. CONCLUSIONS: The management of malignant glaucoma after PMS insertion and its subsequent clinical course is described. Apart from the propensity for a small tube such as the PMS to obstruct with iris when the AC is shallow, management is similar to other scenarios in which malignant glaucoma may develop.

One Year Outcomes and Stability of a Novel Scleral Anchored Intraocular Lens.

PURPOSE: To assess one year results and stability of the implantation of a scleral anchored intraocular lens (IOL). DESIGN: Interventional prospective case series. METHODS: Sixty eyes of 60 patients affected by either aphakia or IOL dislocation were included in this study. Patients underwent vitrectomy, scleral fixation of the IOL, and, if present, dislocated IOL removal. Patients were evaluated preoperatively and at 1, 3, 6, and 12 months after surgery by best-corrected distance visual acuity (BCVA) assessment, intraocular pressure (IOP) measurement, corneal specular microscopy, and optical coherence tomography (OCT) of both the macula and anterior segment. RESULTS: At twelve months, mean BCVA significantly improved (p < 0.0001), and none of the patients experienced a decrease of visual acuity. A 10% decrease of endothelial cell count occurred after surgery. Cystoid macular edema occurred in three patients (5%). A transient increase of intraocular pressure was noted in 7 cases (12%). At one month, horizontal and vertical IOL tilt was 1.04 ± 0.87 and 0.74 ± 0.71 degrees, respectively, and did not significantly change in the follow-up (p > 0.05). None of the patients had decentration or dislocation of scleral-fixated IOL during the follow-up. CONCLUSION: Implantations of scleral plug fixated IOL provide good visual results, low complication rate, and excellent stability of the lens until one-year follow-up.

Macular impairment in mitochondrial diseases: a potential biomarker of disease severity.

The high-energy demands of the retina are thought to contribute to its particular vulnerability to mitochondrial dysfunction. Photoreceptors are the cells with the higher oxygen consumption within the retina, and among these, the cones contain more mitochondria and have a higher energy demand than rods. A cohort of twenty-two patients with genetically-defined mitochondrial diseases (MDs) were enrolled to determine if the macula is functionally and anatomically impaired in these metabolic disorders. Visual acuity and fERG amplitude of patients with primary mitochondrial dysfunction were reduced compared to controls. Furthermore, SD-OCT layer segmentation showed a reduction of retinal and outer nuclear layer (ONL) volume in the macula of the patients. fERG amplitude showed a positive correlation with both ONL volume and thickness. A negative relationship was noted between fERG amplitude and disease severity assessed with Newcastle Mitochondrial Disease Adult Scale. In conclusion, MDs are associated with functional and anatomical alteration of macular cone system, characterized by its strong correlation with clinical disease severity suggesting a role as a potential biomarker of primary mitochondrial disorders.

Spectral domain optical coherence tomography findings in myotonic dystrophy.

The purpose of the study is to evaluate retinal involvement in a cohort of patients affected by Myotonic Dystrophy type 1 (DM1). Both eyes of 30 patients and one eye of a 31st patient with genetically proven diagnosis of DM1 and both eyes of 20 healthy age- and gender-matched subjects were enrolled. All patients underwent complete ophthalmologic examination including best-corrected visual acuity, intraocular pressure measurement, fundoscopy, fundus autofluorescence, infrared imaging and spectral-domain optical coherence tomography with central macular thickness measurement. DM1 patients showed statistically significant higher central macular thickness values than controls. In the DM1 group, butterfly (14.8%) and reticular (13.1%) pigment abnormalities were found with corresponding drusenoid deposit and focal disruption of photoreceptor and retinal pigment epithelium layers. Compared with the controls, DM1 group had higher prevalence of epiretinal membrane. In the DM1 group, the prevalence of epiretinal membrane and retinal pigment epithelium alterations were directly correlated with age, whereas no correlation was found with disease duration, CTG expansion and MIRS score. In conclusion, in addition to the typical retinal pigment epithelium changes, DM1 is also associated with abnormalities of the vitreoretinal interface, particularly epiretinal membrane, resulting in central macular thickness increase. Both inner and outer retinal alterations were associated with increasing age, suggesting that DM1 may cause a premature aging of the retina.

Central Retina Functional Damage in Usher Syndrome Type 2: 22 Years of Focal Macular ERG Analysis in a Patient Population From Central and Southern Italy.

Purpose: Recent studies show that patients with Usher syndrome type 2 (USH2) have abnormal cone structure and density in the central retina. This occurs in the presence of normal acuity, opening the quest for additional sensitive functional measures of central cone function in USH. We tested here whether focal macular cone electroretinogram (fERG) could be such a tool. Methods: This retrospective study of central cone function loss was based on data from 47 patients with USH2 from the Ophthalmology Department of the Policlinico Gemelli/Catholic University in Rome. The analysis focused on the decrease of the fERG, obtained in response to a 41-Hz sinusoidal modulation of a uniform field presented to the central 18°, generated by red light-emitting diodes (LEDs) and superimposed on an equiluminant steady adapting background. fERG decrease was compared with the decrease of best-corrected visual acuity and Goldmann kinetic perimetry V4E field. Results: fERG follow-up data document a severe and precocious loss of central cone function in USH2 patients, preceding losses in other measures of cone function. fERG is already reduced to 40% of control at the beginning of the second decade of life, and by 25 years of age, all USH2 patients have fERGs less than 30% of control values. Conclusions: fERG represents a sensitive tool to evaluate central cone function in USH2, anticipating the decline of other central cone function measures, such as visual acuity and Goldmann perimetry.

Morpho-functional analysis of Stargardt Disease for reading.

OBJECTIVE: To analyze Stargardt disease (STGD) by morpho-functional examination and investigate the relationship between morpho-functional measures and reading performance. DESIGN: Observational case series study. PARTICIPANTS: Fifteen patients with STGD. METHODS: Twenty-six eyes of 15 patients underwent complete ophthalmic evaluation. Spectral domain optical coherence tomography, fundus autofluorescence (FAF), best corrected visual acuity (BCVA), and microperimetric examinations were performed. FAF and optical coherence tomography (OCT) overlap on microperimetric images was obtained in order to evaluate both tomographic and FAF features passing through the eccentric fixation area. Both morphologic features and functional data were correlated with magnification of prescribed device and reading rate. RESULTS: Univariable analysis showed a significant correlation between magnification power and greatest linear dimension of both OCT and FAF (r = 0.69 and r = 0.67; p < 0.05). Magnification power was related to best corrected visual acuity (r = 0.56; p < 0.05). Retinal sensitivity map (r = 0.57; p < 0.05) was considered an indicator of reading rate. Magnification levels showed a positive correlation with eccentric preferred retinal location (p = 0.03) and the degree of FAF alteration (normal, dishomogeneous, ipoautofluorescence; p < 0.0001). CONCLUSIONS: As a result of the overlapping of OCT/FAF imaging on microperimetric exam, residual activity of outer retinal layers passing through the eccentric fixation area seems to be related with required magnification and reading rate. Identification of morpho-functional parameters is helpful for designing a customized rehabilitative program.

Correlation of Macular Focal Electroretinogram with Ellipsoid Zone Extension in Stargardt Disease.

Stargardt disease (STGD1) is the most common cause of inherited juvenile macular degeneration. This disease is characterized by a progressive accumulation of lipofuscin in the outer retina and subsequent loss of photoreceptors and retinal pigment epithelium. The aim of this study was to evaluate the relationship between cone photoreceptor function and structure in STGD1. Macular function was assessed by visual acuity measurement and focal electroretinogram (FERG) recording while spectral domain optical coherence tomography (SD-OCT) imaging was performed to evaluate the integrity of photoreceptors. FERG amplitude was significantly reduced in patients with Stargardt disease (p < 0.0001). The amplitude of FERG showed a negative relationship with interruption of ellipsoid zone (EZ) (R2 = 0.54, p < 0.0001) and a positive correlation with average macular thickness (AMT). Conversely, visual acuity was only weakly correlated with central macular thickness (CMT) (R2 = 0.12, p = 0.04). In conclusion, this study demonstrates that FERG amplitude is a reliable indicator of macular cone function while visual acuity reflects the activity of the foveal region. A precise assessment of macular cone function by FERG recording may be useful to monitor the progression of STGD1 and to select the optimal candidates to include in future clinical trials to treat this disease.

Acute acquired concomitant esotropia and decompensated monofixation syndrome: a sensory-motor status assessment.

OBJECTIVE: To assess and compare sensory-motor status and clinical features of type I and type II acute acquired concomitant esotropia (group A) and decompensated monofixation syndrome (group B). METHODS: In a retrospective, comparative study, 26 patients with a confirmed postoperative diagnosis of type I and II acute acquired concomitant esotropia and monofixation syndrome were enrolled. The 2-tailed unpaired t test and 2-tailed χ(2) test were performed to compare angle of deviation and sensory-motor status under the environmental conditions and after prismatic adaptation test and progressive prism test of 2 groups. RESULTS: All of the patients of group A and 4 patients (33%) of group B experienced diplopia under viewing conditions in the Worth's 4 dot and Bagolini striated glass tests. The TNO stereo test showed the total absence of stereopsis in 6 patients in group B and a significantly lower stereoacuity in group A in the remaining 6 patients (p < 0.0001). The prismatic adaptation test was positive in all of the patients in group B and in 10 patients (71%) in group A (p = 0.39). The value of the angle of deviation after the progressive prism test was significantly higher in group B than in group A (p = 0.02). At the end of the progressive prism test, all of the patients in group A and only 2 patients in group B were orthotropic (p = 0.01). CONCLUSIONS: Bagolini striated glass and Worth's 4 dot tests under viewing conditions and responses under prisms allow for the differentiation of the 2 forms and lead to an accurate aesthetic and functional prognosis.

Bilateral Symmetry of Visual Function Loss in Cone-Rod Dystrophies.

PURPOSE: To investigate bilateral symmetry of visual impairment in cone-rod dystrophy (CRD) patients and understand the feasibility of clinical trial designs treating one eye and using the untreated eye as an internal control. METHODS: This was a retrospective study of visual function loss measures in 436 CRD patients followed at the Ophthalmology Department of the Catholic University in Rome. Clinical measures considered were best-corrected visual acuity, focal macular cone electroretinogram (fERG), and Ganzfeld cone-mediated and rod-mediated electroretinograms. Interocular agreement in each of these clinical indexes was assessed by t- and Wilcoxon tests for paired samples, structural (Deming) regression analysis, and intraclass correlation. Baseline and follow-up measures were analyzed. A separate analysis was performed on the subset of 61 CRD patients carrying likely disease-causing mutations in the ABCA4 gene. RESULTS: Statistical tests show a very high degree of bilateral symmetry in the extent and progression of visual impairment in the fellow eyes of CRD patients. CONCLUSIONS: These data contribute to a better understanding of CRDs and support the feasibility of clinical trial designs involving unilateral eye treatment with the use of fellow eye as internal control.

Neurotrophin family members as neuroprotectants in retinal degenerations.

BACKGROUND AND OBJECTIVES: Inherited retinal degenerations (IRDs) are an untreatable cause of blindness due to photoreceptor apoptosis. Blocking apoptosis by exogenous neurotrophic factor administration is a promising therapeutic strategy in IRDs. The neurotrophin (NT) family are a group of peptide growth factors homologous to nerve growth factor that regulate the development, differentiation, survival, and function of neuronal cells. This mini-review summarizes the preclinical evidence for neuroprotection of photoreceptors by NTs and explores the molecular pathways responsible for this protective effect. METHODS: Studies published in the literature over the past 20 years that report on the effect of NTs on apoptotic photoreceptor death in IRDs and light-induced retinal degeneration, and the cellular pathways involved, are reviewed. RESULTS: Preclinical evidence suggests that exogenous NT administration may be protective against photoreceptor apoptosis. Each NT exerts a neuroprotective effect on photoreceptors that is specific depending upon the model of retinal degeneration and the delivery system. Signaling pathways and retinal cells mediating this effect are still uncertain. Alternatively, different NTs may protect or damage photoreceptors depending on the expression pattern of high- and low-affinity NT receptors on the retinal cells. CONCLUSIONS: Although there is evidence that NTs may exert a protective effect, most likely indirectly on photoreceptor cell apoptotic degeneration in IRDs, the precise cellular and molecular mechanisms underlying this effect are still largely unknown. Better understanding of these mechanisms may greatly improve the rationale and efficacy of NT strategy for treatment of IRDs.

Functional Loss of the Inner Retina in Childhood Optic Gliomas Detected by Photopic Negative Response.

PURPOSE: To determine whether the Ganzfeld ERG photopic negative response (PhNR), an assay of inner retinal activity, is altered in childhood optic glioma (OPG). METHODS: Seventeen pediatric patients with a diagnosis of OPG, established on neuro-ophthalmologic and brain/orbit magnetic resonance imaging (MRI) criteria, were enrolled. The examination protocol included determination of visual acuity (VA), fundus examination, retinal nerve fiber layer (RNFL) measurement with spectral-domain optical coherence tomography (SD-OCT) and photopic ERG. Fifteen normal children served as control group. Ten of the 17 OPG patients were retested 1 to 3 months after the first examination. Photopic ERGs were recorded after 10 minutes of light adaptation in response to a Ganzfeld flash presented on a steady light-adapting background. Amplitude and peak-time of b-wave and PhNR were measured. RESULTS: Compared with normal values, PhNR amplitude was significantly reduced (P < 0.0001) in the OPG group. Peak-time of PhNR as well as b-wave amplitude and peak-time were similar in both patients and controls. Losses of PhNR were found in patients with involvement of either anterior or retro-chiasmatic optic pathways. Linear regression analysis showed significant positive correlation between RNFL thickness and PhNR amplitude (r2 = 0.34, P = 0.008). Mean percentage test-retest difference for PhNR amplitude and peak-time was 12% and 6%, respectively. CONCLUSIONS: These findings indicate that flash ERG PhNR can detect a loss of inner retinal function in childhood OPGs supporting the use of this technique, as an adjunct to standard psychophysical and electrophysiological tests, to monitor visual function in OPG.

Intravitreal dexamethasone implant for acute exudative polymorphous vitelliform maculopathy.

PURPOSE: Acute exudative polymorphous vitelliform maculopathy is a rare retinal disease characterized by bilateral serous macular detachment and subretinal accumulation of yellowish deposits resembling Best dystrophy lesions. Corticosteroid systemic therapy has been used empirically in the attempt to treat this retinal disorder with mixed results. Thus, the benefit of corticosteroid remains undetermined. To our knowledge, we report the first case of acute exudative polymorphous vitelliform maculopathy (AEPVM) treated in one eye with intravitreal dexamethasone implant (Ozurdex; Allergan, Inc., Irvine, California, USA). METHODS: A 28-year-old man with AEPVM underwent intravitreal dexamethasone implantation in the left eye. RESULTS: Compared with the fellow eye, intravitreal dexamethasone implant did not significantly modify the clinical course of the disease. No implant-related complication was experienced during follow-up. CONCLUSIONS: The lack of response to intravitreal dexamethasone seems to suggest that corticosteroids may be ineffective for the treatment of AEPVM.

Assessment of retinal function before and after idiopathic macular hole surgery.

PURPOSE: To evaluate preoperative and postoperative retinal function in patients who underwent macular surgery for idiopathic macular hole. DESIGN: Prospective, comparative, interventional case series. METHODS: Thirty eyes of 30 patients with idiopathic macular hole were included in the study. Patients underwent pars plana vitrectomy and peeling of the internal limiting membrane (ILM). ILM visualization was improved in 15 patients by using triamcinolone acetonide and in the remaining 15 patients by using infracyanine green dye. Spectral-domain optical coherence tomography examination was performed to document macular hole closure. Retinal function was assessed preoperatively and postoperatively over a period of 12 months by best-corrected visual acuity (BCVA) measurement (ETDRS chart), MP-1 microperimetry, and focal electroretinogram recording (fERG). Focal electroretinograms were recorded in response to a sinusoidally modulated (41 Hz), uniform field presented to the macular (18 degrees) and foveal (2.25 degrees) region. RESULTS: Macular hole closure was achieved in all patients in both groups. At 12 months, visual acuity improved in both groups (P < .001), and there were no statistically significant differences between groups. Mean macular sensitivity within the central 2 and 8 degrees increased in both groups, and there were no statistically significant differences between groups at any follow-up. In the triamcinolone acetonide group, 12 months after surgery the amplitude of the fERG's first harmonic (1F) increased both in the macular region (P < .001) and in the foveal region (P < .05). In the infracyanine green group, at 12 months the amplitude of the first harmonic (1F) decreased in both areas. The decrease was significant in the macular region (P < .05) and not significant in the foveal region (P = .095). CONCLUSION: Vitrectomy and ILM peeling assisted with either triamcinolone acetonide or infracyanine green staining improves visual acuity and mean macular sensitivity at 12 months in patients affected by idiopathic macular hole. However, triamcinolone acetonide staining is associated with an increase of fERG's first harmonic amplitude in the foveal and macular region, whereas in the case of infracyanine green staining it seems to decrease after surgery. The reduction of the amplitude of fERG's first harmonic suggests that infracyanine green may have a late toxic effect on photoreceptor cells.