Functional improvement assessed by multifocal electroretinogram after Ocriplasmin treatment for vitreomacular traction.

BACKGROUND: To evaluate the functional recovery of patients with symptomatic vitreomacular traction (VMT) after Ocriplasmin treatment. METHODS: Prospective, single centre, consecutive case series. Patients were treated with a single intravitreal injection of Ocriplasmin (Jetrea, Thrombogenics Inc, USA, Alcon/Novartis EU). The following outcome measures are considered: resolution of VMT, evaluated through the use of optical coherence tomography (SD-OCT), functional recovery evidenced by multifocal-electroretinogram (mfERG) and microperimetry (MP1) after treatment with Ocriplasmin. RESULTS: Four eyes of four patients were treated with Ocriplasmin injection. We observed a VMT non-surgical resolution in all patients. The longitudinal statistical analysis showed a significant improvement of best corrected visual acuity (BCVA) in the treated eye of about 0.97 letters/week (p = 0.033). No significant difference was observed in mean sensitivity (p > 0.05) assessed by MP1 in both eyes, while improvement in fixation stability was assessed in treated eyes (ß = 0.39; p = 0.029). In the four treated eyes mfERG revealed an increased foveal peak response over the follow-up. The longitudinal analysis of mfERG data shows a significant increase of N1 and P1 amplitude in the first rings and a significant decrease of N1 and P1 implicit time in most rings. CONCLUSIONS: We report on four cases with resolution of VMT after Ocriplasmin treatment. Our preliminary results demonstrate that Ocriplasmin is safe and effective in the treatment of VMT, because it not only leads to a morphological recovery but mostly to a restoration of macular functionality, evaluated through the use of different objective tests, such as MP1 and mfERG over a six-month follow-up.

Ocriplasmin use in a selected case with preserved visual acuity.

BACKGROUND: Previous studies described cases of Ocriplasmin injections in patients with vitreo-macular traction and reduced central visual acuity. We describe the first case of a patient with 20/20 visual acuity and vitreo-macular traction treated with Ocriplasmin, and, for the first time in literature, we evaluated the functional changes of the macula in response to pharmacological treatment through multifocal-electroretinogram. CASE PRESENTATION: We report the case of a female Caucasian patient aged 67 years with vitreo-macular traction in the right eye, treated with Ocriplasmin, at the Eye Clinic of the Second University of Naples. Visual acuity was 20/20 before treatment, associated with metamorphopsia. Two weeks after injection, optical coherence tomography showed the release of vitreo-macular traction and multifocal electroretinogram responses showed a significant increase of retinal density responses in all six rings (p < 0.03). Visual acuity remained constant with resolution of symptoms and the appearance of vitreous floaters. CONCLUSION: Intravitreal injection of Ocriplasmin resulted to be a safe and effective treatment in the case here reported. Our data show that the anatomical recovery with release of vitreo-macular traction was associated with a full functional recovery. In fact, the electrical retinal density response of the macular area improved two weeks after Ocriplasmin injection. Further studies with broader inclusion criteria for Ocriplasmin treatment (e.g. also with visual acuity higher than 20/25) on a larger study sample are needed to confirm our results.

Navigated yellow subthreshold micropulse laser for refractory cystoid macular edema following rhegmatogenous retinal detachment surgery.

Purpose: To report the efficacy and safety of navigated 577nm yellow subthreshold micropulse laser (YSML) treatment in a case of refractory cystoid macular edema (CME) following combined phaco-vitrectomy for rhegmatogenous retinal detachment (RRD). Observations: A 69-year-old male patient complained a slow and progressive visual loss in the right eye (RE) since two months. A complete ophthalmological evaluation was performed. Best corrected visual acuity (BCVA) was hand motion and slit lamp examination revealed a nuclear cataract and a total macula-off RRD in the RE. Patient underwent a combined phaco +25 gauge pars plana vitrectomy (PPV) with 5000 cSt silicon oil (SO) tamponade. At the 3-month follow up BCVA was 20/250, retina was completely flat but a macular proliferative vitreoretinopathy (PVR) was detected with swept source optical coherence tomography (SS-OCT) and a second 23 G PPV with PVR peeling and SO removal was performed. At 1 month visit from the second surgery retina was flat and BCVA was 20/200 due to a persistent CME. Oral carbonic anhydrase inhibitors and topical steroids were administered for 2 months without any improvements. At this point, YSML was applied with a macular grid pattern and at three months follow up visit SS-OCT showed a complete resolution of CME, BCVA was 20/100 and these anatomical and functional outcomes were maintained at 6 months follow-up. Conclusions and importance: YSML treatment may be considered a safe and effective treatment strategy for the management of refractory CME following complex RRD surgery cases.

The interplay between sodium/glucose cotransporter type 2 and mitochondrial ionic environment.

Mitochondrial volume is maintained through the permeability of the inner mitochondrial membrane by a specific aquaporin and the osmotic balance between the mitochondrial matrix and cellular cytoplasm. Various electrolytes, such as calcium and hydrogen ions, potassium, and sodium, as well as other osmotic substances, affect the swelling of mitochondria. Intracellular glucose levels may also affect mitochondrial swelling, although the relationship between mitochondrial ion homeostasis and intracellular glucose is poorly understood. This article reviews what is currently known about how the Sodium-Glucose transporter (SGLT) may impact mitochondrial sodium (Na+) homeostasis. SGLTs regulate intracellular glucose and sodium levels and, therefore, interfere with mitochondrial ion homeostasis because mitochondrial Na+ is closely linked to cytoplasmic calcium and sodium dynamics. Recently, a large amount of data has been available on the effects of SGLT2 inhibitors on mitochondria in different cell types, including renal proximal tubule cells, endothelial cells, mesangial cells, podocytes, neuronal cells, and cardiac cells. The current evidence suggests that SGLT inhibitors (SGLTi) may affect mitochondrial dynamics regarding intracellular Sodium and hydrogen ions. Although the regulation of mitochondrial ion channels by SGLTs is still in its infancy, the evidence accumulated thus far of the effect of SGLTi on mitochondrial functions certainly will foster further research in this direction.

Objective Outcomes to Evaluate Voretigene Neparvovec Treatment Effects in Clinical Practice.

PURPOSE: To assess the efficacy of voretigene neparvovec (VN) treatment by objective fixation stability and chromatic pupillometry testing in clinical practice. DESIGN: Retrospective cohort study with longitudinal follow-up. SUBJECTS: Twelve patients (aged 7-34 years) with RPE65-related inherited retinal dystrophies were treated at the same center with VN in both eyes. METHODS: Patients treated at the same center with VN were evaluated over a 12-month posttreatment follow-up by subjective and objective tests. Furthermore, patients treated with VN who developed atrophy were compared with those who did not. MAIN OUTCOME MEASURES: Best-corrected visual acuity (BCVA), full-field stimulus threshold test (FST), semiautomated kinetic visual field (SKVF), microperimetry, and chromatic pupillometry over a 12-month follow-up. RESULTS: Significant improvements of BCVA (P < 0.001), SKVF (P < 0.05), and FST (P < 0.001) were already observed 45 days after treatment and were maintained at the 12-month timepoint. Fixation stability, assessed by microperimetry, improved significantly (P < 0.05) after treatment. Chromatic pupillometry showed significant improvements (P < 0.05) at the 6- and 12-month timepoints. The increase in maximum pupillary constriction significantly (P < 0.001) correlated with higher retinal sensitivity in FST. Four patients developed multifocal retinal atrophy in both eyes, detected at the 6-month timepoint, but this atrophy was not generally associated with worse visual function outcomes. CONCLUSIONS: This study explores objective outcomes in order to demonstrate the efficacy of VN treatment in addition to the tests normally performed in clinical practice. Our findings show a significant improvement of retinal function both in subjective assessments, such as BCVA, SKVF, and FST, and in objective measurements of fixation stability and maximum pupillary constriction. Moreover, the significant correlation between maximum pupillary constriction and light sensitivity thresholds corroborates the introduction of chromatic pupillometry as an objective test to better assess treatment outcomes in patients with inherited retinal dystrophies. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references in the Footnotes and Disclosures at the end of this article.

Adult-onset cyclic esotropia: a case report.

PURPOSE: This case report presents the diagnosis and management of an adult patient with cyclic esotropia, a rare and poorly understood form of strabismus, that is characterized by alternating periods of manifest strabismus and orthotropia. Few cases of adult-onset cyclic strabismus have been reported. The etiology, pathogenesis, and treatment for this condition are reviewed. CASE REPORT: A 37-year-old man with high unilateral myopia and anisometropic amblyopia in his left eye developed cyclic esotropia 2 months after a scleral buckle procedure for a retinal detachment. A 48-hour cycle that consisted of a 24-hour period of orthotropia followed by a 24-hour period of constant left esotropia was present. Magnetic resonance imaging, electromyography, electroencephalography, and ocular and orbital echography were unremarkable, as was a neurological assessment that included fatigue and edrophonium testing. The patient was successfully managed with muscle surgery. CONCLUSIONS: The etiology and pathogenesis of adult-onset cyclic esotropia remain unknown. Cyclic esotropia should be considered in the differential diagnosis when an individual presents with a history of intermittent strabismus that is present some days and not others.

Wall Tension and Tubular Resistance in Kidney Cystic Conditions.

The progressive formation of single or multiple cysts accompanies several renal diseases. Specifically, (i) genetic forms, such as adult dominant polycystic kidney disease (ADPKD), and (ii) acquired cystic kidney disease (ACKD) are probably the most frequent forms of cystic diseases. Adult dominant polycystic kidney disease (ADPKD) is a genetic disorder characterized by multiple kidney cysts and systemic alterations. The genes responsible for the condition are known, and a large amount of literature focuses on the molecular description of the mechanism. The present manuscript shows that a multiscale approach that considers supramolecular physical phenomena captures the characteristics of both ADPKD and acquired cystic kidney disease (ACKD) from the pathogenetic and therapeutical point of view, potentially suggesting future treatments. We first review the hypothesis of cystogenesis in ADPKD and then focus on ACKD, showing that they share essential pathogenetic features, which can be explained by a localized obstruction of a tubule and/or an alteration of the tubular wall tension. The consequent tubular aneurysms (cysts) follow Laplace's law. Reviewing the public databases, we show that ADPKD genes are widely expressed in various organs, and these proteins interact with the extracellular matrix, thus potentially modifying wall tension. At the kidney and liver level, the authors suggest that altered cell polarity/secretion/proliferation produce tubular regions of high resistance to the urine/bile flow. The increased intratubular pressure upstream increases the difference between the inside (Pi) and the outside (Pe) of the tubules (∆P) and is counterbalanced by lower wall tension by a factor depending on the radius. The latter is a function of tubule length. In adult dominant polycystic kidney disease (ADPKD), a minimal reduction in the wall tension may lead to a dilatation in the tubular segments along the nephron over the years. The initial increase in the tubule radius would then facilitate the progressive expansion of the cysts. In this regard, tubular cell proliferation may be, at least partially, a consequence of the progressive cysts' expansion. This theory is discussed in view of other diseases with reduced wall tension and with cysts and the therapeutic effects of vaptans, somatostatin, SGLT2 inhibitors, and potentially other therapeutic targets.

Multimodal Assessment of the Prognostic Role of Ectopic Inner Foveal Layers on Epiretinal Membrane Surgery.

BACKGROUND: To perform a multimodal assessment of the ectopic inner foveal layers' (EIFL) prognostic role on idiopathic epiretinal membrane (ERM) surgery. METHODS: We retrospectively followed-up for 12 months 27 patients who underwent ERM surgery and stratified them based on EIFL presence (group 1) or absence (group 2) at baseline. Central Retinal Thickness (CRT) and best-corrected visual acuity (BCVA) were compared pre- and post-operatively at 1, 4 and 12 months, whereas fixation stability (FS), macular sensitivity (MS) and multifocal electroretinogram (mfERG) responses were confronted at baseline and 12 months. RESULTS: In group 1, BCVA improved at 4 and 12 months (MD = 0.14 (SE = 0.04); MD = 0.13 (SE = 0.05), respectively) as well as in group 2 (MD = 0.31 (SE = 0.07); MD = 0.41 (SE = 0.08), respectively). CRT did not change in group 1, whereas it decreased in group 2 at 4 and 12 months (MD = -73.13; SE = 23.56; MD = -76.20; SE = 23.56). MS showed no changes in both groups after surgery. FS did not change in group 1, whereas group 2 improved FS 2° (+8.91 ± 13.97) and FS 4° (+4.33 ± 3.84). MfERG P1 wave did not change in group 1, while in group 2 αP1-2, αP1-3 and αP1-4 improved postoperatively (27.97 ± 27.62; 12.51 ± 17.36; 10.49 ± 17.19, respectively). CONCLUSIONS: Multimodal assessment confirmed that EIFL negatively affected ERM surgery outcomes.

Visual function and retinal changes after voretigene neparvovec treatment in children with biallelic RPE65-related inherited retinal dystrophy.

To report quantitative retinal changes assessed by spectral-domain optical coherence tomography (SD-OCT) in children treated with voretigene neparvovec (VN) at a single center in Italy. Retrospective review of six consecutive pediatric patients with biallelic RPE65-related dystrophy treated bilaterally with VN. SD-OCT scans were analyzed to extract Early Treatment Diabetic Retinopathy Study (ETDRS) thickness maps of the whole retina and the outer nuclear layer (ONL). Changes in visual function were assessed by best-corrected visual acuity (BCVA) and retinal morphology at Days 30/45 and 180. BCVA significantly improved at Day 30/45 and 6 months (both P < 0.001). Central foveal retinal thickness and central foveal ONL thickness tended to increase (6.4 ± 19.2 µm; P = 0.080 and 3.42 ± 7.68 µm; P = 0.091, respectively). ONL thickness of the internal ETDRS-ring significantly increased at day 30/45 (4.7 ± 8.4 µm; P < 0.001) and day 180 (5.0 ± 5.7 µm; P = 0.009). Intra-operative foveal detachment was not associated with a higher function gain in terms of BCVA, but with a mild thinning of foveal ONL after treatment. The improvement of BCVA and thickening of the ONL layer suggest that improvement of visual acuity could be related to partial recovery of retinal morphology in the perifoveal ring.

RPE65-associated inherited retinal diseases: consensus recommendations for eligibility to gene therapy.

BACKGROUND: This research aimed to establish recommendations on the clinical and genetic characteristics necessary to confirm patient eligibility for gene supplementation with voretigene neparvovec. METHODS: An expert steering committee comprising an interdisciplinary panel of Italian experts in the three fields of medical specialisation involved in the management of RPE65-associated inherited retinal disease (IRD) (medical retina, genetics, vitreoretinal surgery) proposed clinical questions necessary to determine the correct identification of patients with the disease, determine the fundamental clinical and genetics tests to reach the correct diagnosis and to evaluate the urgency to treat patients eligible to receive treatment with voretigene neparvovec. Supported by an extensive review of the literature, a series of statements were developed and refined to prepare precisely constructed questionnaires that were circulated among an external panel of experts comprising ophthalmologists (retina specialists, vitreoretinal surgeons) and geneticists with extensive experience in IRDs in Italy in a two-round Delphi process. RESULTS: The categories addressed in the questionnaires included clinical manifestations of RPE65-related IRD, IRD screening and diagnosis, gene testing and genotyping, ocular gene therapy for IRDs, patient eligibility and prioritisation and surgical issues. Response rates by the survey participants were over 90% for the majority of items in both Delphi rounds. The steering committee developed the key consensus recommendations on each category that came from the two Delphi rounds into a simple and linear diagnostic algorithm designed to illustrate the patient pathway leading from the patient's referral centre to the retinal specialist centre. CONCLUSIONS: Consensus guidelines were developed to guide paediatricians and general ophthalmologists to arrive at the correct diagnosis of RPE65-associated IRD and make informed clinical decisions regarding eligibility for a gene therapy approach to RPE65-associated IRD. The guidelines aim to ensure the best outcome for the patient, based on expert opinion, the published literature, and practical experience in the field of IRDs.

Voretigene Neparvovec Gene Therapy in Clinical Practice: Treatment of the First Two Italian Pediatric Patients.

Purpose: To present visual outcomes of the first two Italian patients with RPE65-related inherited retinal dystrophy (RPE65-IRD) treated with voretigene neparvovec (VN). Methods: Two pediatric patients with RPE65-IRD were treated with VN in both eyes. Patients were evaluated by best-corrected visual acuity (BCVA), full-field stimulus threshold (FST) test, semiautomated kinetic visual field (SKVF), microperimetry, and chromatic pupillometry over 6 months. Results: No complications occurred in the first patient, whereas in the second a subretinal hemorrhage was observed in the first treated eye, and excessive resistance to drug injection occurred during treatment of the second eye. BCVA improved by at least one Early Treatment Diabetic Retinopathy Study line in all treated eyes. The FST test and SKVF showed clinically significant improvements in all eyes (i.e., change of light sensitivity > 10 decibels; area enlargement of at least 20%). Moreover, microperimetry showed better fixation stability. Finally, chromatic pupillometry showed increases in pupillary constriction that ranged from 10% to 20%. All visual changes remained stable during follow-up. Conclusions: The first VN treatments in two pediatric Italian patients in clinical practice showed significant improvements in visual outcomes, even in the case of surgical complications, which spontaneously recovered without sequelae. Translational Relevance: These findings with VN in patients with RPE65-IRD confirm the results of clinical trials.

Changes in neovascular choroidal morphology after intravitreal bevacizumab injection: prospective trial on 156 eyes throughout 12-month follow-up.

BACKGROUND: To report 12-month follow-up results of 156 eyes treated with anti-VEGF for subfoveal choroidal neovascularization (CNV) secondary to age-related macular degeneration, and to verify the efficacy of this treatment in terms of functional results and changes of morphology of choroidal membrane for the different types of choroidal neovascularization analyzed. METHODS: This prospective case series study included subjects with different forms of subfoveal CNV. After the first intravitreal injection of 1.25 mg bevacizumab at baseline, re-injections of bevacizumab were scheduled at least 4 weeks after initial treatment following standardized criteria. RESULTS: One hundred and fifty six patients were divided into two study groups: 60 eyes with classic CNV (group C) and 96 eyes with occult CNV (group O). The improvement in BCVA was greater in group C than group O, although the difference was not statistically significant (P = 0.26). The area of CNV and subretinal fibrous tissue/disciform scar remained stable over time in both groups. The macular thickness significantly decreased through the follow-up period in both groups. The hyper-reflective area of the neovascular complex remained stable in both groups during the first 6 months of follow-up, whereas a slight increase of hyper-reflective lesion size occurred throughout the second 6 months of follow-up. CONCLUSION: The CNV lesion treated with IVB didn't disappear in neither group, but showed less exudation, demonstrated by a decrease in the area of leakage from CNV, subretinal fluid area, and centre point retinal thickness on OCT.

Intravitreal bevacizumab (Avastin) injection for neovascular glaucoma: a survey on 23 cases throughout 12-month follow-up.

AIMS: Neovascular glaucoma (NVG) represents one of the most severe forms of secondary glaucoma, caused by a number of ocular and systemic conditions, which share the common element of retinal ischaemia/hypoxia that initiates the subsequent release of angiogenesis factors, with consequent development of new abnormal vessels through the ciliary body. The aim was to examine the potential efficacy and safety of intravitreal injection of bevacizumab (IVB) (Avastin) in the treatment of NVG in patients who had already undergone the standard retinal ablative procedure. METHODS: This was a prospective pilot trial. Clinical data of 26 eyes from 23 patients, including diagnosis, visual acuity, iris fluorescein angiography stage and intraocular pressure (IOP), were collected. Three injections of bevacizumab were scheduled for each recruited eye at 4-week intervals from the start. All investigations were repeated the day before the IVB (1.25 mg/0.05 ml) and at the 1-, 3-, 6-, 9- and 12-month follow-up. RESULTS: Regression of corneal oedema together with significant pain reduction was achieved in all eyes already after the first IVB, without any noteworthy improvement of visual acuity. At the end of the scheduled protocol (three IVB), regression of iris neovascularization was documented in all patients, together with significant improvement of visual acuity. The IOP reduction from baseline ranged from 30 to 0 mmHg (12.1 +/- 8 mmHg). CONCLUSIONS: Intravitreal bevacizumab, as adjunctive treatment to the standard retinal ablative procedure, seems promising for the management of conditions responsible of retinal ischaemia/hypoxia associated with NVG.

Retinal phototoxicity induced by hydrochlorothiazide after exposure to a UV tanning device.

UV radiation is known to cause acute and chronic eye and skin damage. The present case report describes the occurrence of hydrochlorothiazide-induced retinal phototoxicity immediately after exposure to UV light emanated from a sunbed in a 40-year-old myopic woman. During the tanning session she had always worn UV protective eyewear, except for a few minutes when she took the protective goggles off to put her spectacles on to locate and turn the timer switch off. At baseline her visual acuity was 10/25 in OD and 10/80 in OS. Fundus examination revealed the presence of retinal lesions in both eyes. More specific tests confirmed the presence of a phototoxic macular damage. Hydrochlorothiazide was discontinued, and she was recommended to wear UV filtering glasses. Over the follow-up period (12 months), a slow and progressive visual acuity recovery in both eyes occurred. At the last check the visual acuity improvement was of about 60% from baseline in both eyes. Fundus examination showed only a juxtafoveal flat pigmented scar of the retinal pigment epithelium in both eyes, milder in OD. The constant rise in the number of sunbed users makes the knowledge of UV-related side effects a problem that cannot be postponed further. Awareness of the general public about the harmful effects of UV exposure must represent one of the leading preventive health strategies. Therefore, a careful analysis of the medical history before the admission to a sunbed session throughout a questionnaire could represent an economic and effective measure to avoid further cases of a phototoxic macular damage in patients taking photosensitizing compounds.

An unusual intaocular foreign body.

An unusual foreign body in a 60-year-old man with ocular siderosis is described. A surgical needle was found in the eye after magnetic resonance imaging was performed for cerebral ischemia. As a general precaution in patients who have undergone any kind of surgery, it might be better to perform a plain x-ray before performing magnetic resonance imaging to identify such foreign bodies.

Macular abnormalities in Italian patients with retinitis pigmentosa.

AIM: To investigate the prevalence of macular abnormalities in a large Caucasian cohort of patients affected by retinitis pigmentosa (RP). METHODS: A retrospective study was performed by reviewing the medical records and optical coherence tomography (OCT) scans in a cohort of 581 RP patients in order to assess the presence of macular abnormalities -that is, cystoid macular oedema (CMO), epiretinal membrane (ERM), vitreo-macular traction syndrome, and macular hole. RESULTS: Macular abnormalities were observed in 524 (45.1%) out of the 1161 examined eyes. The most frequent abnormality was CMO, observed in 237 eyes (20.4%) from 133 patients (22.9%), followed by ERM, assessed in 181 eyes (15.6%) from 115 patients (19.8%). Moreover, vitreo-retinal abnormalities were significantly (p<0.05) associated with older age, cataract surgery, or cataract. CMO appeared to be significantly (p<0.05) associated with female gender, autosomic dominant inheritance pattern, and cataract. CONCLUSIONS: Macular abnormalities are more frequent in RP compared to the general population. For that reason, screening RP patients with OCT is highly recommended to follow-up the patients, evaluate the natural history of disease, and identify those patients who could benefit from current or innovative therapeutic strategies.

Recombinant vectors based on porcine adeno-associated viral serotypes transduce the murine and pig retina.

Recombinant adeno-associated viral (AAV) vectors are known to safely and efficiently transduce the retina. Among the various AAV serotypes available, AAV2/5 and 2/8 are the most effective for gene transfer to photoreceptors (PR), which are the most relevant targets for gene therapy of inherited retinal degenerations. However, the search for novel AAV serotypes with improved PR transduction is ongoing. In this work we tested vectors derived from five AAV serotypes isolated from porcine tissues (referred to as porcine AAVs, four of which are newly identified) for their ability to transduce both the murine and the cone-enriched pig retina. Porcine AAV vectors expressing EGFP under the control of the CMV promoter were injected subretinally either in C57BL/6 mice or Large White pigs. The resulting retinal tropism was analyzed one month later on histological sections, while levels of PR transduction were assessed by Western blot. Our results show that all porcine AAV transduce murine and porcine retinal pigment epithelium and PR upon subretinal administration. AAV2/po1 and 2/po5 are the most efficient porcine AAVs for murine PR transduction and exhibit the strongest tropism for pig cone PR. The levels of PR transduction obtained with AAV2/po1 and 2/po5 are similar, albeit not superior, to those obtained with AAV2/5 and AAV2/8, which evinces AAV2/po1 and 2/po5 to be promising vectors for retinal gene therapy.

Combined rod and cone transduction by adeno-associated virus 2/8.

Gene transfer to both cone and rod photoreceptors (PRs) is essential for gene therapy of inherited retinal degenerations that are caused by mutations in genes expressed in both PR types. Vectors based on the adeno-associated virus (AAV) efficiently transduce PRs of different species. However, these are predominantly rods and little is known about the ability of the AAV to transduce cones in combination with rods. Here we show that AAV2/8 transduces pig cones to levels that are similar to AAV2/9, and the outer nuclear layer (mainly rods) to levels that are on average higher, although not statistically significant, than both AAV2/5 and AAV2/9. We additionally found that the ubiquitous cytomegalovirus (CMV), but not the PR-specific GRK1 promoter, transduced pig cones efficiently, presumably because GRK1 is not expressed in pig cones as observed in mice and humans. Indeed, the GRK1 and CMV promoters transduce a similar percentage of murine cones with the CMV reaching the highest expression levels. Consistent with this, the AAV2/8 vectors with either the CMV or the GRK1 promoter restore cone function in a mouse model of Leber congenital amaurosis type 1 (LCA1), supporting the use of AAV2/8 for gene therapy of LCA1 as well as of other retinal diseases requiring gene transfer to both PR types.

Correlation between photoreceptor layer integrity and visual function in patients with Stargardt disease: implications for gene therapy.

PURPOSE: To perform a clinical characterization of Stargardt patients with ABCA4 gene mutation, and to investigate the correlation between the inner and outer segment (IS/OS) junction morphology and visual acuity, fundus lesions, electroretinogram abnormalities, and macular sensitivity. METHODS: Sixty-one patients with Stargardt disease (STGD) were given a comprehensive ophthalmic examination. Inner-outer photoreceptor junction morphology evaluated by spectral-domain optical coherence tomography was correlated with visual acuity, fundus lesions, fundus autofluorescence, full-field and multifocal electroretinography responses, and microperimetric macular sensitivities. We classified STGD patients into three groups: (1) IS/OS junction disorganization in the fovea, (2) IS/OS junction loss in the fovea, and (3) extensive loss of IS/OS junction. Mutation analysis of the ABCA4 gene was carried out by sequencing the complete coding region. RESULTS: A significant difference in visual acuity was observed between IS/OS groups 1 and 2 and between IS/OS groups 2 and 3 (P < 0.0001). A significant difference in microperimetry sensitivity was observed between IS/OS groups 2 and 3, and between IS/OS groups 1 and 3 (P < 0.0001). There was also a statistically significant correlation between IS/OS abnormalities and the extent of fundus lesions (Spearman P ≤ 0.01), as well as with the type of ERG and multifocal ERG results (Spearman P ≤ 0.01). Finally, the degree of IS/OS junction preservation showed a statistically significant correlation with the extension of foveal abnormalities assessed by fundus autofluorescence imaging (Spearman P ≤ 0.01). The G1961E mutation was more frequent in the patients without extensive loss of IS/OS junction (P = 0.01) confirming its association with a milder STGD phenotype. CONCLUSIONS: The results of this study suggest that a comprehensive approach in the examination of Stargardt patients has the potential to improve the understanding of vision loss and may provide a sensitive measure to evaluate the efficacy of future experimental therapies in patients with STGD.