Gene Therapy in Hereditary Retinal Dystrophies: The Usefulness of Diagnostic Tools in Candidate Patient Selections.

PURPOSE: Gene therapy actually seems to have promising results in the treatment of Leber Congenital Amaurosis and some different inherited retinal diseases (IRDs); the primary goal of this strategy is to change gene defects with a wild-type gene without defects in a DNA sequence to achieve partial recovery of the photoreceptor function and, consequently, partially restore lost retinal functions. This approach led to the introduction of a new drug (voretigene neparvovec-rzyl) for replacement of the RPE65 gene in patients affected by Leber Congenital Amaurosis (LCA); however, the treatment results are inconstant and with variable long-lasting effects due to a lack of correctly evaluating the anatomical and functional conditions of residual photoreceptors. These variabilities may also be related to host immunoreactive reactions towards the Adenovirus-associated vector. A broad spectrum of retinal dystrophies frequently generates doubt as to whether the disease or the patient is a good candidate for a successful gene treatment, because, very often, different diseases share similar genetic characteristics, causing an inconstant genotype/phenotype correlation between clinical characteristics also within the same family. For example, mutations on the RPE65 gene cause Leber Congenital Amaurosis (LCA) but also some forms of Retinitis Pigmentosa (RP), Bardet Biedl Syndrome (BBS), Congenital Stationary Night Blindness (CSNB) and Usher syndrome (USH), with a very wide spectrum of clinical manifestations. These confusing elements are due to the different pathways in which the product protein (retinoid isomer-hydrolase) is involved and, consequently, the overlapping metabolism in retinal function. Considering this point and the cost of the drug (over USD one hundred thousand), it would be mandatory to follow guidelines or algorithms to assess the best-fitting disease and candidate patients to maximize the output. Unfortunately, at the moment, there are no suggestions regarding who to treat with gene therapy. Moreover, gene therapy might be helpful in other forms of inherited retinal dystrophies, with more frequent incidence of the disease and better functional conditions (actually, gene therapy is proposed only for patients with poor vision, considering possible side effects due to the treatment procedures), in which this approach leads to better function and, hopefully, visual restoration. But, in this view, who might be a disease candidate or patient to undergo gene therapy, in relationship to the onset of clinical trials for several different forms of IRD? Further, what is the gold standard for tests able to correctly select the patient? Our work aims to evaluate clinical considerations on instrumental morphofunctional tests to assess candidate subjects for treatment and correlate them with clinical and genetic defect analysis that, often, is not correspondent. We try to define which parameters are an essential and indispensable part of the clinical rationale to select patients with IRDs for gene therapy. This review will describe a series of models used to characterize retinal morphology and function from tests, such as optical coherence tomography (OCT) and electrophysiological evaluation (ERG), and its evaluation as a primary outcome in clinical trials. A secondary aim is to propose an ancillary clinical classification of IRDs and their accessibility based on gene therapy's current state of the art. MATERIAL AND METHODS: OCT, ERG, and visual field examinations were performed in different forms of IRDs, classified based on clinical and retinal conditions; compared to the gene defect classification, we utilized a diagnostic algorithm for the clinical classification based on morphofunctional information of the retina of patients, which could significantly improve diagnostic accuracy and, consequently, help the ophthalmologist to make a correct diagnosis to achieve optimal clinical results. These considerations are very helpful in selecting IRD patients who might respond to gene therapy with possible therapeutic success and filter out those in which treatment has a lower chance or no chance of positive results due to bad retinal conditions, avoiding time-consuming patient management with unsatisfactory results.

Vitreo-macular interface disorders in retinitis pigmentosa.

PURPOSE: To investigate the prevalence and progression of vitreo-macular interface disorders (VMID) phenotypes and their natural history in retinitis pigmentosa (RP). METHODS: A total of 257 eyes of 145 RP patients with VMID were retrospectively evaluated. Patients were divided according to the VMID subtypes into epiretinal membranes (ERMs), vitreo-macular traction (VMT) group, and macular hole (MH). Serial eye-tracked spectral-domain optical coherence tomography (SD-OCT) and best-corrected visual acuity (BCVA) changes were analyzed for a mean follow-up of 36.95 months. The status of posterior vitreous cortex was also considered. A control group of 65 eyes belonging to 65 RP patients with no macular changes was also recruited. RESULTS: VMID and control groups had the same baseline BCVA (0.50 vs 0.44 LogMAR) and did not differ in terms of phakic status. Different VMID groups had similar BCVA at baseline (p = 0.98). ERM represented the most prevalent disorder (207/257 eyes, 80.5%), followed by 35/257 (13.6%) VMT, and 15/257 Lamellar MH (LMH) eyes (5.8%). There were no cases of full thickness MH. Throughout the 36.9 months of follow-up, BCVA decreased an average 0.09 LogMAR from 0.31 to 0.4 in VMID patients and 0.01 in controls. VMID subgroup analysis showed a significant BCVA decrease in ERM patients (- 20.29%, p < 0.001), while VMT and LMH did not change significantly. Foveal thickness also remained stable over time. Complete PVD was present in 11 eyes in ERM, VMT, and LMH. CONCLUSIONS: Our study confirms the high prevalence of VMID in RP patients; however, only ERMs determined a significant loss of vision over 24 months. The high prevalence of VMID in RP patients suggests that macular alteration other than edema represents part of disease spectrum.

Retinitis Pigmentosa (RP): The Role of Oxidative Stress in the Degenerative Process Progression.

Purpose: Retinitis Pigmentosa is a term that includes a group of inherited bilateral and progressive retinal degenerations, with the involvement of rod photoreceptors, which frequently leads to blindness; oxidative stress may be involved in the degeneration progression as proposed by several recent studies. The goal of this study is to evaluate whether circulating free radicals taken from capillary blood are related to one of the most important features of Retinitis pigmentosa that can affect frequently patients: cystoid macular oedema (CME). Materials: A total of 186 patients with Retinitis Pigmentosa (range: 25−69 years) were enrolled; all patients completed an ophthalmologic examination and SD-OCT at baseline and were divided into three subgroups according to the SD-OCT features. ROS blood levels were determined using FORT with monitoring of free oxygen radicals. Results: Test levels of free oxygen radicals were significantly increased, almost twice, in RP patients showing cystoid macular oedema and significantly increased compared to the control group. (p < 0.001). Discussion: Our findings suggest that oxidative stress may speed cone photoreceptors' morphological damage (CMT); because long lasting oxidative stress in the RP may cause oxidative damage, with animal models of RP suggesting this is a micromolecular mechanism of photoreceptors' (cone) death, it can be similar to cone damage in human RP eyes. The limitations of this paper are the relatively small sample, the horizontal design of the study, and the lack of data about the levels of ROS in the vitreous body.

Rehabilitative strategies after filtering procedure in glaucoma.

Glaucoma is one of the leading causes of non-reversible blindness worldwide, and almost 6 million people are estimated to be impaired visually in advanced stage of glaucoma. Recently, several studies on glaucoma has been focused towards new therapeutic approaches based on mechanisms independent from IOP control. Effects of new therapeutic agents, visual psychophysical training, or complementary medications targeting optic pathways today seem to be a relevant and effervescent field of research. The goal of the study is to evaluate in glaucoma patients if a rehabilitative strategy with a biofeedback training with microperimetry may be useful after surgery in recovery visual performance even when visual field defects are present in IOP is well controlled environment. Were enrolled 24 patients (28 eyes) with Primary Open Angle Glaucoma (POAG) (mean 63 range: 49-75 years) from our Glaucoma Center after filtering surgery. All patients after one months from surgical intervention underwent to a complete ophthalmologic examination: IOP measurement, gonioscopy, visual field and SD-OCT at baseline of RNFL thickness. In some cases, were included in the study both eyes because in POAG frequently clinical conditions are different in each eye, and secondarily new fixation target retinal location (TRL) was chosen based on single eye retinal sensitivity. Best corrected visual acuity was significantly increased after the training from 0.61 to 0.479 (p = 0.00058) with no change in refractive error. After the biofeedback patients presented increased value in Mean retinal sensitivity from 14.91 to 15.96 (p = 0.0078).Fixation stabilitywas improved either according to Fuji classification (increased from 75.1 to 81.3% p = 0.0073) or BCEA value, reduced from 8.7 to 6.0 square degrees (p = 0.013) we noted a marked increase in this parameter with better performances and satisfaction by the patient. RFNL thickness: no change was noted (p = 0.505) in this value as an indicator of disease's stability. Our data indicate that MP-3 Biofeedback may be a good strategy to reduce the impairment of the Glaucoma Patient.

Clinical Features, Prognosis, and Long-Term Response to Ranibizumab of Macular CNVs in Pattern Dystrophies Spectrum: A Pilot Study.

INTRODUCTION: To analyze the morphological and functional features of choroidal neovascularizations (CNVs) in eyes affected by pattern dystrophies (PD), evaluating their long-term response to intravitreal ranibizumab, and comparing them with CNVs in age-related macular degeneration (AMD). The mean goal is to identify possible disease biomarkers and to evaluate the long-term prognosis of CNVs in PD. MATERIALS AND METHODS: A retrospective study of 42 patients with naïve CNV (26 PD and 16 AMD), for a total of 47 eyes (29 eyes in the PD group and 18 eyes in the AMD group). Each patient received a loading dose of ranibizumab (one monthly for three months) followed by pro re nata (PRN) reinjection protocol for a period of at least three years. Morphological OCT parameters (CRT, central retinal thickness; SRF, subretinal fluid; IRF, intraretinal fluid; SHRM, subretinal hyperreflective material; HRF, hyperreflective foci; HCD, hyperreflective crystalline deposits; cCT, central choroidal thickness; slCT, sublesional choroidal thickness; EZd, ellipsoid zone disruption; and best corrected visual acuity (BCVA in logMAR scale)) were reported at baseline and last follow-up. RESULTS: At baseline, no significant differences were found between the two groups, except for choroidal thickness parameters that were significantly greater in the PD group (p = 0.009). Longitudinal PD analysis demonstrated reduction in BCVA (p = 0.009), decrease in CRT (p = 0.046), resolution of SRF in 61.6% of cases (p = 0.004) and SHRM in 30% (p = 0.034), and choroidal thinning both centrally (p = 0.004) and sublesional (p = 0.011) compared to baseline. At 3 years, the PD group received significantly more injections than the AMD (p = 0.011) and showed significantly thicker choroid (p = 0.033) and more frequent HRF (p = 0.006). Regarding the PD group, we found a negative correlation between age and choroidal thicknesses at baseline and at 3 years (p < 0.05); significant positive correlations were found between baseline BCVA and at 3 years (p < 0.001), BCVA at 3 years and IRF (p = 0.003) and SHRM at 3 years (p = 0.003); CRT baseline and CRT 3 years (p = 0.017); HCD at 3 years was associated with greater CRT (p = 0.04) and IRF at 3 years (p = 0.019). CONCLUSIONS: Early and long-term morphofunctional features of CNVs in PD and in AMD are overlapping. CNVs in PD have poorer long-term response to ranibizumab and higher choroidal thickness suggesting different pathogenetic and evolutionary mechanisms.