Traumatology of the optic nerve and contribution of crystallins to axonal regeneration

Within a few decades, the repair of long neuronal pathways such as spinal cord tracts, the optic nerve or intracerebral tracts has gone from being strongly contested to being recognized as a potential clinical challenge. Cut axonal stumps within the optic nerve were originally thought to retract and become irreversibly necrotic within the injury zone. Optic nerve astrocytes were assumed to form a gliotic scar and remodelling of the extracellular matrix to result in a forbidden environment for re-growth of axons. Retrograde signals to the ganglion cell bodies were considered to prevent anabolism, thus also initiating apoptotic death and gliotic repair within the retina. However, increasing evidence suggests the reversibility of these regressive processes, as shown by the analysis of molecular events at the site of injury and within ganglion cells. We review optic nerve repair from the perspective of the proximal axon stump being a major player in determining the successful formation of a growth cone. The axonal stump and consequently the prospective growth cone, communicates with astrocytes, microglial cells and the extracellular matrix via a panoply of molecular tools. We initially highlight these aspects on the basis of recent data from numerous laboratories. Then, we examine the mechanisms by which an injury-induced growth cone can sense its surroundings within the area distal to the injury. Based on requirements for successful axonal elongation within the optic nerve, we explore the models employed to instigate successful growth cone formation by ganglion cell stimulation and optic nerve remodelling, which in turn accelerate growth. Ultimately, with regard to the proteomics of regenerating retinal tissue, we discuss the discovery of isoforms of crystallins, with crystallin beta-b2 (crybb2) being clearly upregulated in the regenerating retina. Crystallins are produced and used to promote the elongation of growth cones. In vivo and in vitro, crystallins beta and gamma additionally promote the growth of axons by enhancing the production of ciliary neurotrophic factor (CNTF), indicating that they also act on astrocytes to promote axonal regrowth synergistically. These are the first data showing that axonal regeneration is related to crybb2 movement within neurons and to additional stimulation of CNTF. We demonstrate that neuronal crystallins constitute a novel class of neurite-promoting factors that probably operate through an autocrine and paracrine mechanism and that they can be used in neurodegenerative diseases. Thus, the post-injury fate of neurons cannot be seen merely as inevitable but, instead, must be regarded as a challenge to shape conditions for initiating growth cone formation to repair the damaged optic nerve.

Long-term morphometric stabilization of regenerating retinal ganglion cells in the adult rat

PURPOSE

Adult retinal ganglion cells (RGCs) can regenerate their cut axons within peripheral nerve grafts used to replace the distal optic nerve stump. We examined the long-term stabilization of RGCs by guiding their regenerating axons into different termination areas.

METHODS

The optic nerve (ON) of adult rats was completely cut intraorbitally and its ocular stump was connected with different visual target areas (cortex, midbrain) or with non-visual areas (e.g. muscle). Control groups consisted of blind ending graft and ON cut without graft. The function of the retina was regularly examined by electroretinography. At one, six and nine months postsurgery RGCs were retrogradely labelled with 4-(4-(didecylamino)styryl)-N-methylpyridinium iodide and examined morphometrically. Regenerating RGCs were categorized into three major classes representing the morphological types I, II and III.

RESULTS

Our data show that regenerating RGCs remain stable up to nine months after grafting at the ON, although the numbers of axons are low, that is less than 1%, and this number is not significantly effected by reconnection with targets. However, there are significant quantitatively and morphometrically assessable differences between the experimental groups depending on the tissue the RGCs are connected with visual targets. Regenerating RGCs show the highest stability in morphology if reconnected with visual target tissue.

CONCLUSIONS

Adult RGCs of the rat can be reconnected with visual centers using a peripheral nerve graft. This reconnection stabilizes the cells at morphological and the retina at functional levels for a long period of time, although it does not significantly increase cell survival.

Amniotic membrane induces peroxisome proliferator-activated receptor-γ positive alternatively activated macrophages

PURPOSE

Amniotic membrane transplantation (AMT) reportedly improves herpetic stromal keratitis (HSK). Here we studied the role of the amniotic membrane (AM) on macrophages.

METHODS

BALB/c mice with necrotizing HSK received an AMT or tarsorrhaphy (TAR) as control. Apoptosis of F4/80+ cells was determined using the annexinV/7-AAD system. Macrophage invasion was determined using a cornea invasion assay. Cytokine secretion was quantified by ELISA. Arginase activity was measured by bioassay. Expression of nuclear factor (NF)-κB or peroxisome proliferator-activated receptor (PPAR)-γ related proteins was detected by Western blot analysis, and the expression of costimulatory surface molecules or PPAR-γ by flow cytometry. Lipid accumulation was observed by Oil red O and Sudan B staining.

RESULTS

After AMT apoptotic features of corneal macrophages, but also macrophage invasion increased. IL-6, IL-10, IL-12, TNF-α, and NF-κB content in HSK corneas had decreased with AMT. AMT increased expression of PPAR-γ, arginase 1 and 2, and arginase activity in AM-treated HSK corneas. In vitro, NF-κB, cytokine production, costimulatory molecules (CD80, CD86, CD40), phagocytic capacity, proliferation, viability, and accessory function to herpes simplex virus (HSV)-1 specific draining lymph node (DLN) cells were reduced in bone marrow derived macrophages (BM) cocultured with AM, while CD206, CD204, CD163, and CD68, lipid accumulation in the cytoplasm, PPAR-γ expression, and arginase activity was increased. An increase in viability and proliferation was observed in the presence of AM combined with apoptotic cells, compared with AM alone.

CONCLUSIONS

Based on these results it can be concluded that the action mechanism of AM is associated with modulation of classically activated macrophages into alternatively activated macrophages or macrophage cell death, probably by engaging lipid metabolism and activating the PPAR-γ pathway, consequently curtailing effector T cell functions. Apoptotic cells induced in the environment with AM support the presence and survival of such macrophages.

Inflammation and immunology of the vitreoretinal compartment

The immune system protects organisms against environmental and endogenous pathogens. By complex mechanisms, it regulates the homeostasis of inflammatory processes and tissue repair mechanisms. In the retina, these pathways can result in an irreversible tissue scar, which is related to malfunction and loss of function. In the aging retina, inflammation plays a major role and causes adverse effects. Several ophthalmological diseases contain aspects of maladjusted inflammatory processes. This review summarizes the general function of the immune system and its regulatory mechanisms in the vitreoretinal compartment. Next to non-pathological inflammatory processes, the review presents aspects of inflammation in the aging retina, AMD, glaucoma, uveitis and diabetic retinopathy. A better understanding of the complex immunology of the eye and inflammation of the vitreoretinal compartment may guide us towards more effective therapies for these very prevalent eye conditions.

VEGF, Ang-2 and SRIF associated abnormal postnatal development of the retinal capillary network in the Royal College of Surgeons rat

To examine retinal angiogenesis in the Royal College of Surgeons rat (RCS) serving as a model for ischemic proliferative retinopathies at morphological, proteomic and mRNA levels in order to evaluate the interplay of morphological and molecular changes in the course of the disease. Photoreceptor degeneration was confirmed by histological cross-sections and optical coherence tomography. The capillary retinal network was visualized in RCS rats aged between 14 and 45 days (P14-P45) by perfusion with high molecular weight fluorescein isothiocyanate-labeled dextran and compared with corresponding Sprague-Dawley rats. Vascular crosstalks within central areas to peripheral retinal eccentricities were analyzed. The expression of vascular growth-associated factors and their receptors in the course of the abnormal vascular development, namely vascular endothelial growth factor (VEGF), VEGF receptor subtype 1 (VEGF-R1) and -2 (VEGF-R2), somatostatin (SRIF), somatostatin receptor subtype 2 (Sstr-2), angiopoietin-2 (Ang-2) and tyrosine kinase with immunoglobulin-like and EGF-like domains 2 (Tie-2), was analyzed by immunohistochemistry, western blotting and quantitative real-time polymerase chain reaction. Underperfused areas without capillarization were found in the middle and peripheral retinal eccentricities of RCS rats until P29. Through the course of vascularization previously low perfused areas became completely perfused, but were characterized by significantly increased neovascularizations. Western blotting revealed specific expression of growth-associated factors and their receptors in the course of capillary development. VEGF was significantly increased until P29 in RCS rats, while SRIF was significantly upregulated at P21 and P29 at proteomic level in SD rats. At mRNA level Ang-2 was significantly upregulated in RCS rats at P29, VEGF-R1 and VEGF-R2 at P36 and SRIF at P36. Initial incomplete perfusion is followed by aberrant vessel formation. VEGF, SRIF, Ang-2 and their receptors are regulated at protein and mRNA levels, providing therapeutic possibilities for treating ischemic proliferative retinopathies in the course of the disease.

Alpha2-adrenergic receptors and their core involvement in the process of axonal growth in retinal explants

PURPOSE

To determine the patterns of α2-adrenergic receptor (α2-AR) subtype expression in normal and degenerated retinas and to analyze the response of these receptors to the α2-AR agonist brimonidine tartrate (BT).

METHODS

The binding characteristics of α2-ARs in the retina were evaluated in experimental and matching sham groups by in vitro quantitative autoradiographic saturation with [(3)H]-clonidine. Retinal explants from juvenile and adult rats with either elevated intraocular pressure or after optic nerve crush (ONC) were cultured with BT over 96 hours in vitro to analyze the effects of BT on axonal growth by videomicroscopy and axon counting. Changes in retinal protein expression by BT were monitored by two-dimensional gel electrophoresis (2D-PAGE) and matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS).

RESULTS

The total number of α2-ARs in the retina increased significantly after ONC compared with the sham group. BT supported axonal growth in the juvenile, glaucomatous, and injured retinas (P < 0.004) most effectively at a concentration of 0.001 mg/mL, without influencing the axonal growth rate. Immediate supplementation of BT was more effective than delayed supplementation (P < 0.001). Proteomic analysis revealed treatment-specific expression patterns of glial fibrillary acidic protein (GFAP), glucose-related protein (GRP)58, platelet-activating factor (PAF), and laminin-binding protein (LBP).

CONCLUSIONS

These data are the first to show differences in α2-AR expression in normal and degenerated retinas. BT supports neuronal growth in cultured retinal pieces, suggesting that α2-ARs play a role in retinal metabolism.

Expression and biophysical characterization of voltage-gated sodium channels in axons and growth cones of the regenerating optic nerve

PURPOSE

Successful regeneration and re-establishment of synaptic connections in the adult central nervous system is a complex process determined by both the exterior environment and the endogenous neural activity of the regenerating growth cones. The purpose of this study was to determine the expression and properties of voltage-gated sodium channels (Na(v)) expressed by regenerating growth cones.

METHODS

Na(v) channels were studied in an organotypic explant culture of the adult rat retina by immunocytochemistry and whole-cell, patch-clamp recordings.

RESULTS

Regenerating axons and growth cones, but not glial processes, expressed Na(v) channels. Whole-cell, current-clamp recordings from growth cones displayed a high input resistance of 1.29 GOmega and a resting membrane potential of -69.0 mV. All growth cones responded to depolarizing voltage steps with fast, transient, inward currents mediated by Na(+) ions, followed by slow, sustained outward K(+) currents. Half-maximum activation clustered in two groups, suggesting the presence of at least two Na(v) channel isoforms. Steady state inactivation and recovery from fast inactivation were characterized by a half-maximum value of -69.7 mV and by a time constant of 3.64 ms, respectively. Injection of depolarizing current steps larger than threshold (-29.3 mV) consistently induced a single action potential, whereas ganglion cell bodies responded to above-threshold stimulation with a series of fast, all-or-none action potentials.

CONCLUSIONS

These experiments describe for the first time the biophysical properties of Na(v) channels recorded from the growth cones of regenerating retinal ganglion cells and contrast their properties with those of adult retinal ganglion cells.

Valproic acid-mediated neuroprotection and regeneration in injured retinal ganglion cells

PURPOSE

Valproic acid (VPA) has been demonstrated to have neuroprotective effects in neurodegenerative conditions. VPA inhibits histone-deacetylases (HDAC) and delays apoptosis in degenerating neurons. The authors investigated whether VPA delays retinal ganglion cell (RGC) death and enhances axonal regeneration after optic nerve crush (ONC). Furthermore, potential molecular targets involved in VPA-mediated protection were analyzed.

METHODS

ONC was performed on the left eye of rats, which received VPA or Ringer's solution subcutaneously (SC; 300 mg/kg twice daily) or intravitreally (single postlesional injection). Densities of fluorogold-labeled RGC were analyzed in retinal flatmounts after 5 or 8 days. Retinal tissue was also harvested and processed to quantify axon growth in retinal explants; evaluate caspase-3 activity; analyze transcription factor cAMP response element binding protein (CREB); and determine acetylated histone 3 and 4, as well as phosphorylated extracellular signal-regulated kinase (pERK) 1/2.

RESULTS

Five and 8 days after ONC, 93% and 58% RGC survived after subcutaneous VPA treatment in comparison to Ringer's solution (62% and 37% viable RGC), respectively (P < 0.001). Likewise, a single intravitreal injection of VPA immediately after injury significantly delayed apoptosis in RGC (P = 0.0016). Injured RGC treated with VPA showed better regeneration of their axons in culture (196 axons/explant) than the crushed controls receiving Ringer (115 axons/explant). RGC axons of the right control eyes regenerated more after VPA treatment. VPA-mediated neuroprotection and neuroregeneration were accompanied by decreased caspase-3 activity, CREB induction, pERK1/2 activation, but not by altered histone-acetylation.

CONCLUSIONS

VPA provided neuroprotection and axonal regrowth after ONC. Alterations were observed in several pathways; however, the precise mechanism of VPA-mediated protection is not yet fully understood.

GM-CSF regulates the ERK1/2 pathways and protects injured retinal ganglion cells from induced death

Granulocyte-macrophage-colony-stimulating-factor (GM-CSF) is a potent hematopoietic cytokine. In the present study, we examined whether GM-CSF is neuroprotective in retinal ganglion cells (RGCs). First, we studied the expression of GM-CSF and the GM-CSF-alpha-receptor in rat and human retina and in RGC-5 cells. Then, RGC-5 cells were incubated with apoptosis-inducing agents (e.g., staurosporine, glutamate and NOR3). The cell death was assessed by Live-Death-Assays and apoptosis-related-proteins were examined by immunoblotting. In addition, the expression of phosphorylated ERK1/2-pathway-proteins after incubation with GM-CSF and after inhibiting MEK1/2 with U0126 was analyzed. To assess the in vivo-effect, first staurosporine or GM-CSF plus staurosporine was injected into the vitreous body of Sprague-Dawley rats. In a second axotomy model the optic nerve was cut and GM-CSF was injected into the vitreous body. In both models, the RGCs were labeled retrogradely with either Fluoro-Gold or 4-Di-10-Asp and counted. As a first result, we identified GM-CSF and the GM-CSF-alpha-receptor in rat and human retina as well as in RGC-5 cells. Then, in the RGC-5 cells GM-CSF counteracts induced cell death in a dose-and time-dependent manner. With respect to apoptosis, Western blot analysis revealed a decreased Bad-expression and an increased Bcl-2-expression after co-incubation with GM-CSF. Concerning signaling pathways, incubation with GM-CSF activates the ERK1/2 pathway, whereas inhibition of MEK1/2 with U0126 strongly decreased the phosphorylation downstream in the ERK1/2 pathway, and the antiapoptotic activity of GM-CSF in vitro. Like in vitro, GM-CSF counteracts the staurosporine-induced cell death in vivo and protects RGCs from axotomy-induced degeneration. Our data suggest that GM-CSF might be a novel therapeutic agent in neuropathic disease of the eye.

ROCKs are expressed in brain tumors and are required for glioma-cell migration on myelinated axons

The interactions between migrating glioma cells and myelinated fiber tracts are poorly understood. We identified that C6 glioma cells can migrate along myelinated chicken retinal axons in a novel coculture, thereby expressing small GTPases of the Rho family and serine/threonine Rho-associated kinases (ROCKs). We found that the ROCK1 isoform is also highly expressed in native human high-grade gliomas. Glioma cells migrated faster in vitro along myelinated axons than on laminin-1, with the former but not the latter being specifically and reversibly blocked by the ROCK inhibitor Y27632. These data suggest that the mechanisms underlying the migration of glioma cells on myelinated axons differ from those underlying the migration on extracellular matrix molecules such as laminin-1.

[Ophthalmological symptoms as key findings in neurosyphilis--diagnosis and therapy]

BACKGROUND

The incidence of neurosyphilis, one of the late manifestations of syphilis, is reemerging. Affection of the eye is often associated with the disease. It may present with various clinical symptoms, leading to diagnostic difficulties. In cases of early diagnosis and adequate treatment the prognosis of the disease is good.

PURPOSE

The purposes of this study are 1. to analyse clinical manifestations of patients with neurosyphilis on ophthalmological symptoms and 2. to demonstrate the course of the disease and the visual outcome in patients with optic nerve affection in neurosyphilis treated with standard therapy (penicillin G) or adjunct steroids.

METHODS

We performed 1. a retrospective analysis of all 23 patients who were treated for neurosyphilis between 2000-2008 at this centre and 2. evaluated a case series of 4 patients with optic nerve affection in neurosyphilis who were treated with penicillin and adjunct methylprednisolone.

RESULTS

91% of the patients with neurosyphilis showed ocular affection in various presentations. The optic nerve was affected in 78%. In 43% ocular symptoms were the exclusive sign of the neurosyphilis. In all patients who were treated with penicillin, visual acuity improved. Adjunct treatment with methylprednisolone resulted in complete visual recovery in two cases.

CONCLUSION

Ocular symptoms serve as the key diagnostic findings in neurosyphilis. Treatment of choice is penicillin G. Adjunct treatment with methylprednisolone may improve the visual outcome in patients with optic nerve involvement.

Engrafted chicken neural tube-derived stem cells support the innate propensity for axonal regeneration within the rat optic nerve

PURPOSE

Injury to the adult optic nerve, caused mechanically or by diseases, is still not reparable because the retinal ganglion cells (RGCs) are not allowed to regrow their axons and die retrogradely, although they possess the intrinsic propensity to regenerate axons in experimental conditions.

METHODS

In vitro propagated embryonic stem cells derived from the early chicken neural tube (NTSCs) were used to examine whether transplanted NTSCs produce growth-promoting factors and pave the microenvironment, thus facilitating axonal regeneration within the rat optic nerve.

RESULTS

NTSCs survived within the site where the optic nerve had been cut and continued to be nestin-positive, thus preserving their undifferentiated cell phenotype. Transplanted NTSCs activated the matrix metalloproteases (MMP)-2 and -14 in glial fibrillary acidic protein (GFAP)-positive optic nerve astrocytes. MMP2 production correlated with immunohistochemically visible degradation of inhibitory chondroitin sulfate proteoglycans (CSPGs). In addition, NTSCs produced a panoply of neurite-promoting factors including oncomodulin, ciliary neurotrophic factor, brain-derived neurotrophic factor and crystallins beta and gamma. Cut axons intermingled with NTSCs and passed through the zone of injury to enter the distal optic nerve over long distances, arriving at the thalamus and midbrain.

CONCLUSIONS

This study showed evidence that paving of the distal optic nerve microenvironment with proteolytically active MMPs and providing stem-cell-derived growth factors is a suitable method for facilitating regenerative repair of the optic nerve. Understanding the molecular mechanisms of this repair has fundamental implications for development of NTSC-based subsidiary therapy after neural injuries.

Cholinergic inhibition by botulinum toxin in a rat model of congenital glaucoma raises intraocular pressure

BACKGROUND

Cholinergic receptors are crucially involved in the regulation of intraocular pressure (IOP). Muscarinic agonists in the trabecular meshwork tissue increase aqueous humour outflow facility by a direct stimulation of ciliary muscle contraction. We investigated the contribution of cholinergic state to IOP regulation.

METHODS

Intracameral injections of botulinum toxin A (BTA) were applied in a group with four normotensive rats and a group with four glaucoma rats (genetic glaucoma model). BTA is a potent neurotoxin which inhibits presynaptic cholinergic transmission for 6-8 weeks. The same amount of saline was injected in a third group of four normotensive rats (sham condition). IOP measurements were performed preoperatively, as well as 1, 2 and 4 weeks postoperatively. Afterwards, the rat eyes were removed and subjected to immunhistochemistry and western blotting analysis using antibodies against choline acetyltransferase (CHAT).

RESULTS

Mean IOP in both normotensive groups was unaltered compared with the preoperative status. The glaucoma group showed a significant increase in the mean IOP (Student test, p<0.05) and a signal reduction for CHAT by immunolabelling in the trabecular meshwork compared with the other two groups. Western blotting confirmed the decreased expression of CHAT.

CONCLUSION

Our results suggest that modification of the cholinergic status in the normotensive eye does not significantly affect the IOP; cholinergic regulation of the ciliary trabecular meshwork may have differential levels of control, apart from the ciliary muscle contraction. Moreover, it seems that differential expression of the muscarinic receptors may be responsible for the decreased trabecular cholinergic state occurring in this rat model of glaucoma.

Acute keratoconus induced by hypothyroxinemia during pregnancy

Keratoconus is a bilateral non-inflammatory corneal ectasia with an incidence of approximately 1 per 2000 in the general population. The etiology of keratoconus is multifactorial, although not completely understood. Several clinical observations suggest that thyroid gland dysfunction is associated with keratoconus pathophysiology. Pregnancy represents a major alteration in the maternal endocrinologic status characterized by modified function of the thyroid gland. We report on a 33-yr-old pregnant women suffering from keratoconus, who presented simultaneously with a remarkable deterioration of the disease during gestation and with thyroid gland dysfunction. Acute keratoconus in this patients coincided with the lowest plasma T4 level reached during pregnancy. During the third trimester of gestation, the keratoconus receded significantly. Here we provide direct evidence in support of a possible linkage between keratoconus and thyroid gland dysfunction, assumed by previous clinical observations. This case report is the first to suggest that changes in maternal thyroid hormone levels during pregnancy can aggravate the progression of keratoconus.

Translin-associated factor-X (Trax) is a molecular switch of growth-associated protein (GAP)-43 that controls axonal regeneration

The ability of neurons to form axons requires the choreographed assembly of growth cones. We show that there is a time window from postnatal day 14 (P14) until P21/22 when axons of rat retinal ganglion cells will regenerate under serum-free culture conditions. In contrast, no outgrowth occurred before P13, and growth declined from P22 and ceased after P30. Using proteomics, we have identified translin-associated factor X (Trax), a DNA-binding factor that is expressed during this period of postnatal development. Trax is shown to coexpress with growth-associated protein GAP-43. Small interfering RNA-mediated inhibition of Trax expression resulted in downregulation of both Trax and GAP-43 transcripts and protein both before and during the period of regeneration (P8) and (P16). In contrast, silencing of Trax at P30 resulted in significant upregulation of the GAP-43 transcript and protein and induced outgrowth of axons. These data suggest that Trax regulates GAP-43 transcription and regeneration-promoting effects during the postnatal maturation period. Trax may represent a new potent therapeutic target gene for optic nerve and spinal cord injuries.

Treatment of basal cell carcinoma of the eyelids with 5% topical imiquimod: a 3-year follow-up study

BACKGROUND

The aim of this study was to determine the efficacy and safety of 5% topical imiquimod, and the long-term results following its use, in the treatment of nodular basal cell carcinoma (BCC) of the eyelid.

METHODS

Imiquimod cream (5%) was applied topically to five individuals affected by nodular BCC of the eyelid. The patients were followed up during the 6 weeks of treatment and for another 3 years after treatment. Local side effects and evidence of tumour regression or recurrence were noted.

RESULTS

Complete clinical clearance of the tumour was obtained in four patients, with no response in the fifth patient. Therapy was typically accompanied by significant discomfort due to local side effects, which disappeared following completion of the treatment. None of these patients showed any local recurrence after 3 years.

CONCLUSIONS

Topical imiquimod applied in the form of a 5% cream proved to be a safe, efficacious and sustainable treatment option for nodular BCC of the eyelid in our selected cases.

Computer based vision restoration therapy in glaucoma patients: a small open pilot study

PURPOSE

Several studies have shown that computer-based visual stimulation improves detection performance in brain damaged patients with post-chiasmatic lesions after stroke or trauma. Because it is not known whether visual field defects after retinal lesions can also be modified by visual stimulation we explored if visual field enlargements are possible in patients with glaucoma.

METHODS

Five patients with primary open angle glaucoma (POAG) performed Vision Restoration Training (VRT), a computer-based vision training for a total of 6 months in two 3-months blocks with a 3-months training-free interval between the two training periods. Perimetric testing was performed with High Resolution Perimetry (HRP) as well as with 30 degrees and 70 degrees white/white (W/W) and 30 degrees blue/yellow (B/Y) conventional automatic perimetry (Oculus Twinfield).

RESULTS

After the first 3 months of training the average detection performance significantly increased in HRP (Z= -2.023, p<0.05) and in 30 degrees W/W perimetry (Z= -2.023, p<0.05), but not in B/Y perimetry (Z= -1.214, p=0.225) or in the 70 degrees W/W perimetry, which included more peripheral, non-trained areas (Z= -0.406, p=0.684). Visual improvements remained stable after the training-free interval. Measured by HRP after the second VRT period 3 patients achieved an increase in the ability to detect visual stimuli, however, this improvement did not reach significance (Z= -1.826, p=0.068).

CONCLUSIONS

While a small patient sample does not permit general conclusions on visual field recovery after glaucoma, this pilot study suggests that visual field defects caused by retinal lesion may be improved by systematic vision stimulation. A larger sample, randomized clinical trial is now warranted.