Intraoperative complications of robotic-assisted extended totally extraperitoneal (eTEP) ventral hernia retromuscular repairs with mesh: a systematic literature review and narrative synthesis.

Minimally invasive extended totally extraperitoneal (eTEP) technique is revolutionising ventral hernia repairs. Robotic-assisted eTEP has been gaining popularity due to better visual clarity and greater dexterity provided by the robotic systems, compared to laparoscopy. Despite growing number of papers being published each year, so far, no study has explored intraoperative complications in robotic-assisted eTEP. The aim was to perform a systematic literature review on the incidence of intraoperative complications in robotic-assisted eTEP ventral hernia repairs. The study protocol was preregistered with PROSPERO, registration number CRD42023450072. Twelve categories of intraoperative complications were defined by the authors. A search of PubMed and Embase was conducted on 16/08/2023, for articles pertaining to robotic-assisted eTEP operations in ventral hernias in adults. Articles were critically appraised and data were extracted using predefined extraction templates. No data were suitable for statistical analysis and a narrative synthesis was performed instead. Ten studies fulfilled the inclusion criteria, of which four studies reported intraoperative complications. Of the 12 categories of intraoperative complications, only 5 were reported. Three studies encountered adherent bowel inside the hernia sac. One reported linea alba injury with subsequent anterior layer dehiscence. There was one case of unrecognised intraoperative retromuscular bleeding and one case of insufflation injury with subcutaneous emphysema. There is a paucity of literature on the incidence of intraoperative complications in robotic-assisted eTEP ventral hernia repairs. Available studies suggest complication rates are low. More robust studies using prospective data from hernia registries are required before further conclusions can be drawn.

Leber Hereditary Optic Neuropathy Gene Therapy: Longitudinal Relationships Among Visual Function and Anatomical Measures.

PURPOSE: To assess longitudinal relationships among visual function and anatomical measures of gene therapy in G11778A Leber hereditary optic neuropathy (LHON). DESIGN: Phase 1 clinical trial. METHODS: This was a single-institution study of patients with G11778A LHON. Patients with chronic bilateral visual loss >12 months (group 1, n = 11), acute bilateral visual loss <12 months (group 2, n = 9), or unilateral visual loss (group 3, n = 8) were administered unilateral intravitreal AAV2(Y444,500,730F)-P1ND4v2 injection with low, medium, high, and higher doses to worse eye for groups 1 and 2 and better eye for group 3. Oucome measures were best-corrected visual acuity (BCVA), visual field mean deviation (VF MD), steady-state pattern electroretinogram (SS-PERG), optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness and ganglion cell+inner plexiform layer (GCIPL) thickness, and National Eye Institute Visual Function Questionnaire (NEI-VFQ-25) scores. Mean follow-up was 33.6 months (range = 18-36 months). RESULTS: Baseline SS-PERG amplitude was much reduced in both eyes of all groups including asymptomatic eyes of group 3, and showed no appreciable changes irrespective of disease stage and treatment. Significant and progressive GCIPL and RNFL thinning occurred in all eyes; BCVA and VF MD fluctuated in treated and fellow eyes, with some eyes having modest improvement that may be related to natural history or to gene therapy. Mean NEI-VFQ-25 scores declined in group 3 subjects (P = .023), CONCLUSION: Asymptomatic eyes in LHON patients with unilateral visual loss may be beyond the window of effective neuroprotection given reduced GCIPL and SS-PERG. Randomization of patients to an untreated control group would help to assess treatment effect by accounting for variable natural history. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Mitochondrially Targeted Gene Therapy Rescues Visual Loss in a Mouse Model of Leber's Hereditary Optic Neuropathy.

Leber's hereditary optic neuropathy (LHON) is a common mitochondrial genetic disease, causing irreversible blindness in young individuals. Current treatments are inadequate, and there is no definitive cure. This study evaluates the effectiveness of delivering wildtype human NADH ubiquinone oxidoreductase subunit 4 (hND4) gene using mito-targeted AAV(MTSAAV) to rescue LHOH mice. We observed a declining pattern in electroretinograms amplitudes as mice aged across all groups (p < 0.001), with significant differences among groups (p = 0.023; Control vs. LHON, p = 0.008; Control vs. Rescue, p = 0.228). Inner retinal thickness and intraocular pressure did not change significantly with age or groups. Compared to LHON mice, those rescued with wildtype hND4 exhibited improved retinal visual acuity (0.29 ± 0.1 cy/deg vs. 0.15 ± 0.1 cy/deg) and increased functional hyperemia response (effect of flicker, p < 0.001, effect of Group, p = 0.004; Interaction Flicker × Group, p < 0.001). Postmortem analysis shows a marked reduction in retinal ganglion cell density in the LHON group compared to the other groups (Effect of Group, p < 0.001, Control vs. LHON, p < 0.001, Control vs. Rescue, p = 0.106). These results suggest that MTSAAV-delivered wildtype hND4 gene rescues, at least in part, visual impairment in an LHON mouse model and has the therapeutic potential to treat this disease.

Comparison of different gene-therapy methods to treat Leber hereditary optic neuropathy in a mouse model.

Introduction: Therapies for Leber hereditary optic neuropathy (LHON), in common with all disorders caused by mutated mitochondrial DNA, are inadequate. We have developed two gene therapy strategies for the disease: mitochondrial-targeted and allotopic expressed and compared them in a mouse model of LHON. Methods: A LHON mouse model was generated by intravitreal injection of a mitochondrialtargeted Adeno-associated virus (AAV) carrying mutant human NADH dehydrogenase 4 gene (hND4/m.11778G>A) to induce retinal ganglion cell (RGC) degeneration and axon loss, the hallmark of the human disease. We then attempted to rescue those mice using a second intravitreal injection of either mitochondrial-targeted or allotopic expressed wildtype human ND4. The rescue of RGCs and their axons were assessed using serial pattern electroretinogram (PERG) and transmission electron microscopy. Results: Compared to non-rescued LHON controls where PERG amplitude was much reduced, both strategies significantly preserved PERG amplitude over 15 months. However, the rescue effect was more marked with mitochondrial-targeted therapy than with allotopic therapy (p = 0.0128). Post-mortem analysis showed that mitochondrial-targeted human ND4 better preserved small axons that are preferentially lost in human LHON. Conclusions: These results in a pre-clinical mouse model of LHON suggest that mitochondrially-targeted AAV gene therapy, compared to allotopic AAV gene therapy, is more efficient in rescuing the LHON phenotype.

Gene therapy restores mitochondrial function and protects retinal ganglion cells in optic neuropathy induced by a mito-targeted mutant ND1 gene.

Therapies for genetic disorders caused by mutated mitochondrial DNA are an unmet need, in large part due barriers in delivering DNA to the organelle and the absence of relevant animal models. We injected into mouse eyes a mitochondrially targeted Adeno-Associated-Virus (MTS-AAV) to deliver the mutant human NADH ubiquinone oxidoreductase subunit I (hND1/m.3460 G > A) responsible for Leber's hereditary optic neuropathy, the most common primary mitochondrial genetic disease. We show that the expression of the mutant hND1 delivered to retinal ganglion cells (RGC) layer colocalizes with the mitochondrial marker PORIN and the assembly of the expressed hND1 protein into host respiration complex I. The hND1-injected eyes exhibit hallmarks of the human disease with progressive loss of RGC function and number, as well as optic nerve degeneration. We also show that gene therapy in the hND1 eyes by means of an injection of a second MTS-AAV vector carrying wild-type human ND1 restores mitochondrial respiratory complex I activity, the rate of ATP synthesis and protects RGCs and their axons from dysfunction and degeneration. These results prove that MTS-AAV is a highly efficient gene delivery approach with the ability to create mito-animal models and has the therapeutic potential to treat mitochondrial genetic diseases.

Factors influencing interhospital transfer delays in emergency general surgery: a systematic review and narrative synthesis.

BACKGROUND: Emergency general surgery is an emerging public health issue globally, with substantial healthcare burden. Interhospital transfer of critically unwell surgical patients has been the mainstay of bridging gaps in surgical coverage in regional and rural locations, despite evidence of greater morbidity and mortality. Delays in transfer invariably occurs and compounds the situation. Our aim was to examine the factors influencing interhospital transfer delays in emergency general surgical patients. METHODS: A systematic search of PubMED and EmBase, was performed by two researchers from 2020 to 23rd Feb 2021, for English articles related to interhospital transfer delays in emergency general surgical patients, with an age of >16. Articles were critically appraised and data were extracted into a pre-specified data extraction form. No data was suitable for statistical analysis and a narrative synthesis was performed instead. RESULTS: Six relevant articles were identified from the search. All studies were retrospective cohort studies with moderate to high risk of bias. Lack of consultant surgeon input, after hours transfer, need for intensive care bed and poor transfer documentation may have a role in interhospital transfer delays. Patients with public health insurance, multiple comorbidities and non-emergency medical conditions experience longer transfer request time and may be at risk of precipitating interhospital transfer delays. Transfer delays are seen in transfers over longer distances. CONCLUSION: There is a paucity of knowledge on what and how factors influence interhospital transfer delays in emergency general surgical patients. Well-designed prospective cohort studies are required to bridge this knowledge gap.

The Relationship Between Stage of Leber's Hereditary Optic Neuropathy and Pattern Electroretinogram Latency.

Purpose: The purpose of this study was to compare the baseline steady-state pattern electroretinogram (SS-PERG) of patients with G11778A Leber hereditary optic neuropathy (LHON) with different stages of visual acuity (VA) loss before allotopic gene therapy (GT). Methods: Patients (n = 28) were enrolled into groups (GT I: chronic bilateral VA ≤35 Early Treatment Diabetic Retinopathy Study [ETDRS]; GT II: acute bilateral VA ≤35 ETDRS; GT III: acute unilateral, VA ≤35 ETDRS, and better eye VA ≥70 ETDRS) and tested with SS-PERG together with 210 age-matched normal controls (NCs). SS-PERG amplitude (nV) and latency (ms) of each eye were averaged for groups GT I, GT II, and NC. Symptomatic eyes (GT III-S) and asymptomatic eyes (GT III-A) of group GT III were included separately and accounted for by using generalized estimating equation (GEE) methods. Results: Compared to NC, SS-PERG amplitudes were reduced similarly by approximately 50% (P < 0.001) among all GT groups (NC > GT I, GT II, GT III-S, and GT III-A). SS-PERG latencies were shorter by ≥3.5 ms in all LHON groups and differed by disease stage (G III-A < NC, P = 0.002; GT III-S < GT III-A, P = 0.01; GT II < GT III-S, P = 0.03; GT I < NC, P < 0.001, but not different from other GT groups, all P > 0.1). Conclusions: Although SS-PERG amplitude reduction did not distinguish between disease stages, SS-PERG latency shortening occurred in asymptomatic eyes and symptomatic eyes and distinguished between disease stages. Translational Relevance: SS-PERG latency shortening is consistent with primary damage of smaller/slower axons and sparing of larger/faster axons and may provide an objective staging of LHON, which may be helpful to determine efficacy in LHON trials.

Leber Hereditary Optic Neuropathy Gene Therapy: Adverse Events and Visual Acuity Results of All Patient Groups.

PURPOSE: To assess safety of gene therapy in G11778A Leber hereditary optic neuropathy (LHON). DESIGN: Phase 1 clinical trial. METHODS: Setting: single institution. PARTICIPANTS: Patients with G11778A LHON and chronic bilateral visual loss >12 months (group 1, n = 11), acute bilateral visual loss <12 months (group 2, n = 9), or unilateral visual loss (group 3, n = 8). INTERVENTION: unilateral intravitreal AAV2(Y444,500,730F)-P1ND4v2 injection with low, medium, high, and higher doses to worse eye for groups 1 and 2 and better eye for group 3. OUTCOME MEASURES: Best-corrected visual acuity (BCVA), adverse events, and vector antibody responses. Mean follow-up was 24 months (range, 12-36 months); BCVAs were compared with a published prospective natural history cohort with designated surrogate study and fellow eyes. RESULTS: Incident uveitis (8 of 28, 29%), the only vector-related adverse event, resulted in no attributable vision sequelae and was related to vector dose: 5 of 7 (71%) higher-dose eyes vs 3 of 21 (14%) low-, medium-, or high-dose eyes (P < .001). Incident uveitis requiring treatment was associated with increased serum AAV2 neutralizing antibody titers (p=0.007) but not serum AAV2 polymerase chain reaction. Improvements of ≥15-letter BCVA occurred in some treated and fellow eyes of groups 1 and 2 and some surrogate study and fellow eyes of natural history subjects. All study eyes (BCVA ≥20/40) in group 3 lost ≥15 letters within the first year despite treatment. CONCLUSIONS: G11778A LHON gene therapy has a favorable safety profile. Our results suggest that if there is an efficacy effect, it is likely small and not dose related. Demonstration of efficacy requires randomization of patients to a group not receiving vector in either eye.

Teaching middle ear anatomy using a novel three-dimensional papercraft model.

BACKGROUND: The middle ear is a complex anatomical space which is difficult to interpret from two-dimensional imagery. Appropriate surgical knowledge of the area is required to operate, yet current anatomical teaching methods are costly and hard to access for the trainee. METHODS: A papercraft 3D design involving anatomical elements added separately to a model was designed, and then peer-validated by medical students and junior doctors. Preliminary quantitative assessment was performed using an anatomical labelling questionnaire, with six students given a lecture to act as a control. Qualitative feedback was also gathered. RESULTS: 18 participants were recruited for the study. A total of 12 models were constructed by 6 medical students and 6 junior doctors. 6 medical students received a lecture only. Qualitative feedback was positive and suggested the model improved knowledge and was useful, yet timing and complexity were issues. Students scored, on average, 37% higher after completing the model, with junior doctors also improving anatomical knowledge, though these differences were not significant (p > 0.05). CONCLUSIONS: In this initial investigation, the model was shown to be an engaging way to learn anatomy, with the tactile and active nature of the process cited as benefits. Construction of the model improved anatomical knowledge to a greater extent than a classical lecture in this study, though this difference was not significant. Further design iterations are required to improve practical utility in the teaching environment, as well as a larger study.

Non-invasive Assessment of Central Retinal Artery Pressure: Age and Posture-dependent Changes.

Purpose: Assessment of Ocular Perfusion Pressure (OPP) requires estimation of the Mean Central Retinal Artery Pressure (MCRAP) [OPP = MCRAP-IOP]. In a seated position, MCRAP is currently estimated as 2/3 of the Mean Arterial Pressure (MAP) to account for the hydrostatic reduction of MAP at eye level. We tested a surrogate method for direct MCRAP assessment by measuring MAP with Arm-Up and cuff at eye level (AUMAP) at different postures and ages. Methods: MAP and AUMAP were assessed in a mixed population of 136 subjects (mean age 44 ± 17.39 years) including healthy participants (N = 30) and patients with optic neuropathies (Glaucoma suspects, N = 14; Open-Angle Glaucoma, N = 26, LHON, N = 19; MS, N = 47) not expected to alter systemic blood pressure. None of the subjects had history of carotid stenosis or pharmacological treatment to regulate blood pressure. AUMAP was also tested in two subgroups in supine (N = 42) and -10° Head Down body Tilt position (HDT, N = 46). Results: In the seated position, both 2/3MAP and AUMAP increased with increasing age, however with steeper (2x) slope for AUMAP (P < .0001). With decreasing angle of body tilt, AUMAP increased while MAP decreased. The mean AUMAP/MAP ratio (posture coefficient) was, seated, 0.73 (SE 0.003); supine, 0.90 (SE 0.005); HDT, 0.97 (SE 0.005). In the seated position only, the AUMAP/MAP ratio significantly increased with age (P < .0001). Mean posture coefficients obtained with AUMAP were in the range of those based on either direct ophthalmodynamometric measurements or hydrostatic estimations. Conclusions: Surrogate measurement of MCRAP in individual subjects is feasible using the simple AUMAP approach that provides a straightforward estimation of OPP (OPP = AUMAP - IOP) at different body postures. The standard method OPP = 2/3*MAP-IOP in the seated posture underestimates OPP at older ages. Clinical estimation of OPP would benefit from the use of AUMAP, in particular for head-down postures.

Mitochondrial Transfer of the Mutant Human ND6T14484C Gene Causes Visual Loss and Optic Neuropathy.

Purpose: To evaluate the long-term effects of mitochondrial gene transfer of mutant human NADH ubiquinone oxidoreductase subunit VI (hND6T14484C) in the mouse eye. Methods: Adult mice were injected intravitreally with mitochondrial-targeted adeno-associated virus carrying either hND6T14484C or mitochondrial encoded mCherry. The delivery and expression of the interest gene were detected by polymerase chain reaction (PCR), quantitative PCR (qPCR), and immunostaining. The pathologic effects of the mutant gene in live mice were assessed with RNA-seq, serial spectral domain optical coherence tomography (SD-OCT), and pattern electroretinogram (PERG). Results: Delivered hND6 was found 30-fold greater than endogenous mouse ND6 in microdissected retinal ganglion cells of hND6-injected mice. Compared to controls injected with mCherry, PERG amplitude of hND6 mice dropped significantly at 3 (P = 0.0023), 6 (P = 0.0058), and 15 (P = 0.031) months after injection. SD-OCT revealed swelling of the optic nerve head followed by the progressive retinal and optic nerve atrophy in hND6 mice. Furthermore, RNA-seq data showed a change in 381 transcripts' expression in these mice compared to mCherry mice. Postmortem analysis showed hND6 mice had marked atrophy of the entire optic nerve, from the globe to the optic chiasm, and a significant loss of retinal ganglion cells compared to age-matched control mice (P = 1.7E-9). Conclusions: Delivered hND6T14484C induces visual loss and optic neuropathy in mice, the hallmarks of human Leber's hereditary optic neuropathy (LHON). Translational Relevance: Results from this study will help establish a novel strategy not only to generate an LHON animal model but also to provide a potential to treat this or any other mitochondrial diseases.

XIAP Protects Retinal Ganglion Cells in the Mutant ND4 Mouse Model of Leber Hereditary Optic Neuropathy.

Purpose: Leber hereditary optic neuropathy (LHON) is a genetic form of vision loss that occurs primarily owing to mutations in the nicotinamide adenine dinucleotide dehydrogenase (ND) subunits that make up complex I of the electron transport chain. LHON mutations result in the apoptotic death of retinal ganglion cells. We tested the hypothesis that gene therapy with the X-linked inhibitor of apoptosis (XIAP) would prevent retinal ganglion cell apoptosis and reduce disease progression in a vector-induced mouse model of LHON that carries the ND4 mutation. Methods: Adeno-associated virus (AAV) encoding full length hemagglutinin-tagged XIAP (AAV2.HA-XIAP) or green fluorescent protein (AAV2.GFP) was injected into the vitreous of DBA/1J mice. Two weeks later, the LHON phenotype was induced by AAV delivery of mutant ND4 (AAV2.mND4FLAG) to the vitreous. Retinal function was assessed by pattern electroretinography. Optic nerves were harvested at 4 months, and the effects of XIAP therapy on nerve fiber layer and optic nerve integrity were evaluated using immunohistochemistry, transmission electron microscopy and magnetic resonance imaging. Results: During LHON disease progression, retinal ganglion cell axons are lost. Apoptotic cell bodies are seen in the nuclei of astrocytes or oligodendrocytes in the optic nerve, and there is thinning of the optic nerve and the nerve fiber layer of the retina. At 4 months after disease onset, XIAP gene therapy protects the nerve fiber layer and optic nerve architecture by preserving axon health. XIAP also decreases nuclear fragmentation in resident astrocytes or oligodendrocytes and decreases glial cell infiltration. Conclusions: XIAP therapy improves optic nerve health and delays disease progression in LHON.

Comparison of microscopic and endoscopic views in cadaveric ears.

PURPOSE: The advent of endoscopic otosurgery provides reduced tissue destruction with theoretically improved views, yet a quantification of the difference of exposure between microscopic and endoscopic approaches has not yet been performed in human specimens. The objective of this study was to assess the difference in views of cadaveric tympanic membranes when inspected with operating microscopes or endoscopes. METHODS: A circular graduated disc was inserted into eight cadaveric external ear canals to rest against the tympanic membrane. Three independent observers assessed the maximum possible observable radius of the graduated disc in each ear using a 0° endoscope and a surgical microscope in superior, inferior, posterior, and anterior directions. RESULTS: The endoscope was able to view a significantly larger mean maximum visible radius than the microscope in posterior, superior, anterior, and inferior directions. This represented a mean gain in observable distance of 19.18%. There was a smaller variation in mean maximum visible radius than the microscope. CONCLUSION: The wider field of view in an endoscope compared to a microscope implies reduced surgical tissue damage is needed to provide sufficient operative exposure. Enhanced views of the attic were demonstrated by the endoscope, further indicating utility in cholesteatoma observation and surgery.

Gene Therapy with Single-Subunit Yeast NADH-Ubiquinone Oxidoreductase (NDI1) Improves the Visual Function in Experimental Autoimmune Encephalomyelitis (EAE) Mice Model of Multiple Sclerosis (MS).

Mitochondrial dysfunction mediated loss of respiration, oxidative stress, and loss of cellular homeostasis contributes to the neuronal and axonal degenerations permanent loss of function in experimental autoimmune encephalomyelitis model (EAE) of multiple sclerosis (MS). To address the mitochondrial dysfunction mediated visual loss in EAE mice, self-complementary adeno-associated virus (scAAV) containing the NADH-dehydrogenase type-2 (NDI1) complex I gene was intravitreally injected into the mice after the onset of visual defects. Visual function assessed by pattern electroretinogram (PERGs) showed progressive loss of function in EAE mice were improved significantly in NDI1 gene therapy-treated mice. Serial optical coherence tomography (OCT) revealed that progressive thinning of inner retinal layers in EAE mice was prevented upon NDI1 expression. The 45% optic nerve axonal and 33% retinal ganglion cell (RGC) loss contributed to the permanent loss of visual function in EAE mice were ameliorated by NDI1-mediated prevention of mitochondrial cristae dissolution and improved mitochondrial homeostasis. In conclusion, targeting the dysfunctional complex I using NDI1 gene can be an approach to address axonal and neuronal loss responsible for permanent disability in MS that is unaltered by current disease modifying drugs.

Longterm Reversal of Severe Visual Loss by Mitochondrial Gene Transfer in a Mouse Model of Leber Hereditary Optic Neuropathy.

In many human disorders mitochondrial dysfunction is central to degeneration of retinal ganglion cells. As these cells do not regenerate, vision is irreversibly lost. Here we show reversal of visual dysfunction by a mitochondrially targeted adeno associated virus in transgenic mice harboring a G11778A mutation in the ND4 subunit of complex I persists longterm and it is associated with reduced loss of RGCs and their axons, improved oxidative phosphorylation, persistence of transferred ND4 DNA and transcription of ND4 mRNA.

Thomas Secker M.D.: Archbishop and man-midwife.

This paper provides a biographical outline of the career of Thomas Secker, MD, who from 1758-68 was Archbishop of Canterbury. Although much has been written on Secker, this study seeks to highlight his training in medicine, which has been largely overlooked hitherto by historians.

Gene Therapy for Leber Hereditary Optic Neuropathy: Low- and Medium-Dose Visual Results.

PURPOSE: To determine the effects of AAV2(Y444,500,730F)-P1ND4v2 in patients with Leber hereditary optic neuropathy (LHON). DESIGN: Prospective open-label, unilateral single-dose, intravitreal injection of AAV2(Y444,500,730F)-P1ND4v2 per participant. PARTICIPANTS: Fourteen patients with visual loss and mutated G11778A mitochondrial DNA. METHODS: Intravitreal injection with the gene therapy vector AAV2(Y444,500,730F)-P1ND4v2 into 1 eye. Six participants with chronic bilateral visual loss lasting more than 12 months (group 1), 6 participants with bilateral visual loss lasting less than 12 months (group 2), and 2 participants with unilateral visual loss (group 3) were treated. Nine patients had at least 12 months of follow-up. Clinical testing included visual acuity, visual fields, optical coherence tomography, pattern electroretinography, and neuro-ophthalmic examinations. Generalized estimating equation methods were used for longitudinal analyses. MAIN OUTCOME MEASURE: Loss of visual acuity. RESULTS: For groups 1 and 2, month 12 average acuity improvements with treatment relative to baseline were 0.24 logarithm of the minimum angle of resolution (logMAR). Fellow eyes had a 0.09-logMAR improvement. A post hoc comparison found that at month 12, the difference between study eye minus fellow eye improvement in group 2 patients of 0.53 logMAR was greater than that observed in our prior acute natural history patients of 0.21 logMAR (P = 0.053). At month 18, the difference between study eye minus fellow eye improvement in our acute group 2 gene therapy patients of 0.96 was more than that observed in our prior acute natural history patients (0.17 logMAR; P < 0.001). Two patients demonstrated asymptomatic uveitis that resolved without treatment. Optical coherence tomography of treated eyes showed an average temporal retinal nerve fiber layer thickness of 54 µm before injection and 55 µm at month 12. For fellow eyes before injection, it was 56 µm, decreasing to 50 µm at month 12 (P = 0.013). Generalized estimating equations suggested that PERG amplitudes worsened more in treated eyes than in fellow eyes by approximately 0.05 µV (P = 0.009 exchangeable). No difference between eyes in outcomes of other visual function measures was evident. CONCLUSIONS: Allotopic gene therapy for LHON at low and medium doses seems to be safe and does not damage the temporal retinal nerve fiber layer, opening the door next for testing of the high dose.