Nerve Head Research Articles

Retinal astrocyte morphology predicts integration of vascular and neuronal architecture.

Astrocytes are important regulators of blood flow and play a key role in the response to injury and disease in the central nervous system (CNS). Despite having an understanding that structural changes to these cells have consequences for local neurovascular physiology, individual astrocyte morphology remains largely unexplored in the retina. Here, we used MORF3 mice to capture full membranous morphology for over fifteen hundred individual astrocytes in the mouse retina, a highly metabolically active component of the CNS. We demonstrate that retinal astrocytes have been misrepresented as stellate in morphology due to marker use like GFAP and S100β which underestimates cell complexity. We also find that astrocytes contain recurring morphological motifs which are predictive of the underlying neurovascular architecture of the inner retina and suggestive of function. These motifs predict fine sampling and integration of retinal ganglion cell electrical activity with consequences for blood flow regulation. Additionally, our data shows that astrocytes participate in neurovascular interactions to a much greater degree than currently reported. 100% of cells contact the vasculature through one of three mutually exclusive classes of connections. Similarly, 100% of cells contact some neuronal element, be it an RGC axon or soma. Finally, we report that astrocyte morphology depends on retinal eccentricity, with cells appearing compressed near the nerve head and in the periphery. These results reveal a large degree of astrocyte morphological complexity that informs their contribution to neurovascular coupling in the retina.

Профилактика интраоперационного кровотечения из новообразованной сосудистой сети диска зрительного нерва в хирургии осложненных случаев пролиферативной диабетической ретинопатии

Proliferative diabetic retinopathy (PDR) is a major cause of vision loss in diabetic patients and is characterized by neovascularization particularly in optic nerve head (NVD). NVD may bleed spontaneously or be caused by minimal trauma. During vitrectomy, it is often difficult to stop this type of bleeding, thus surgeons are faced with such a problem as poor visualization and residual hemorrhage in the early postoperative period. Aim was to evaluate the clinical efficacy of the platelet-rich plasma (PRP) use in intraoperative bleeding from the NVD during the surgical treatment of PDR. Material and Methods. The group consists of 12 patients (12 eyes). Preoperative examination of all patients revealed the vitreous hemorrhage as well as the retinal traction detachment according to B-scan. A standard three-port vitrectomy (25 g) was performed, accompanied with the removal of proliferated blood vessels, diathermic coagulation, endolaser coagulation of the retina and an intravitreal injection of PRP on the NVD (PRP obtained by one-step closed centrifugation). Vitreal cavity was tamponaded with air. Results. We achieved an almost complete cessation of bleeding into vitreal cavity from NVD in all participants by using the intravitreal injection of the PRP. Conclusion. Intravitreal injection of PRP on the optic disc during vitrectomy is effective and safe. Keywords: proliferative diabetic retinopathy, PDR , neovascularization of the disc, vitreous hemorrhage, platelet-rich plasma, PRP, vitrectomy

Amyloid Precursor Protein in Abusive Head Trauma Suspects

To study orthograde axonal transport with amyloid precursor protein (APP-A4) immunohistochemistry (IHC) in the retina and lamina cribrosa (LC) portion of the optic nerve in abusive head trauma (AHT) suspects. Retrospective, case-control study. Seventy-two eyes from suspected AHT victims referred by the Los Angeles Coroner and control eyes from nontraumatized infants were included. IHC was conducted using University of California, Irvine (UCI), Lab Medicine Department's standard protocol and results analyzed by light microcopy after paraffin processing. Quantitation of LC APP-A4 block was estimated in 21 cases with known survival using MetaMorph, a proprietary biomicroscopy imaging software. The presence or absence of APP-A4 label accumulations in retinal ganglion cells, nerve fiber layer at the disc margin, and in LC axonal bundles were compared to matching tissues from nontraumatized control eyes with only background staining. Among the globes from AHT suspects with nerve heads available for study, 94% were positive for LC accumulation of marker. Among suspect AHT cases with known survival after injury of 1 to 1588 days, most demonstrated LC APP-A4 accumulations. Our findings reinforce a recent publication based on APP-A4 IHC that demonstrated similar orthograde axonal transport block in the LC in children with AHT and recommend that intraocular pressures be recorded and addressed in these patients.

Effect of fasting on diurnal fluctuation of parafoveal and peripapillary vessel density and related oculodynamic and haemodynamic parameters.

To investigate the effects of Ramadan fasting on diurnal superficial-deep parafoveal vessel density (pfVD) and nerve head (NH)-radial peripapillary capillary (RPC) peripapillary vessel density (ppVD) using optical coherence tomography angiography (OCTA), as well as other related oculodynamic and haemodynamic parameters, and to compare these findings with those in the nonfasting period in healthy individuals. A total of 105 healthy individuals, 42 women and 63 men, were included in this prospective study. OCTA was used to examine the superficial-deep pfVD and NH-RPC ppVD. In the third week of Ramadan, OCTA readings were obtained twice daily at 08:00 and 16:00 hour (h) under fasting conditions and compared with nonfasting values 2 weeks after Ramadan. Both intraocular pressure (IOP) and blood pressure values were assessed accordingly. The mean age (23-51) of individuals was 34.37 ± 7.04 years. In comparison with the 08:00 -h values, the 16:00 -h IOPs, superficial-deep pfVDs and RPC ppVDs were substantially reduced both during the fasting and nonfasting periods (P = 0.001, P = 0.009, P = 0.006, P = 0.006, P = 0.004, P = 0.004, P = 0.41, P = 0.032 and P = 0.021). No differences were found in the diurnal change of superficial-deep pfVDs, NH-RPC ppVDs, IOPs and mean ocular perfusion pressures (MOPPs) between the fasting and nonfasting periods, whereas the same was not true for mean arterial blood pressures (MABPs) (P = 0.049). The parafoveal and peripapillary VDs (except for NHpp-VD) and IOPs were found to have decreased significantly throughout the day both in fasting and nonfasting periods. Our study confirms the diurnal changes in the IOPs, MOPPs, superficial-deep pfVDs and NH-RPC ppVDs under dehydration and normal terms.

PO 18145 - Anatomical structures at risk in proximal fifth metatarsal fracture fixation

Introduction: Proximal fifth metatarsal fracture fixation is usually treated conservatively, but when chosen for surgical treatment, percutaneous fixation with screws is the most used. This study aims to evaluate the presence of injury of the structures at risk and to measure the distance of these structures to the entry point. Methods: Eleven fresh-frozen below-the-knee specimens underwent standard operative fixation for a Jones fracture via the “High and inside” percutaneous technique. A guide wire was placed through the medullary canal and confirmed on fluoroscopy. The cannulated drill with a drill sleeve was then placed over the wire and advanced to the diaphysis. The guide wire was left, and the skin and subcutaneous tissues were carefully removed from the lateral midfoot to fully expose the structures at risk. The guidewire was then removed, and then the solid screw was placed. Neurovascular and tendinous structures were assessed for any injury. The distance of the wire in the base of the fifth metatarsal and these structures was measured and documented, including the branches of the sural nerve, cuboid, fourth metatarsal, peroneus longus, and peroneus brevis tendons. Results: The structure with the shortest average distance from the pin was the peroneus brevis, measuring 0.91 mm (±1.22 mm S.D.), followed by the cuboid articular surface, sural nerve, peroneus longus, and base of the fourth metatarsal, respectively. The pin had damaged the peroneus brevis in 5 of 11 cadavers. The average distance from the tendon insertion point was 7.2 mm. The furthest measured distance was 10 mm, while the closest was 3 mm. The screw head contacted the articular surface of the cuboid in 3 of 11 cadavers. There were no instances of pin contact with or damage to the peroneus longus, sural nerve, or fourth metatarsal head. Conclusion: We conclude that percutaneous fixation of fractures of the base of the fifth metatarsus presents a risk of partial lesion of the peroneus brevis tendon and lateral aspect of the cuboid. Therefore, specific care with these structures should be taken during the procedure.

Contrast-Enhanced 3D-FLAIR Imaging of the Optic Nerve and Optic Nerve Head: Novel Neuroimaging Findings of Idiopathic Intracranial Hypertension.

The sensitivity of contrast-enhanced 3D-FLAIR has not been assessed in patients with idiopathic intracranial hypertension. The purpose of this study was to evaluate whether hyperintensity of the optic nerve/optic nerve head on contrast-enhanced 3D-FLAIR imaging is associated with papilledema in patients with idiopathic intracranial hypertension. A retrospective review was conducted from 2012 to 2015 of patients with clinically diagnosed idiopathic intracranial hypertension and age- and sex-matched controls who had MR imaging with contrast-enhanced 3D-FLAIR. Two neuroradiologists graded each optic nerve/optic nerve head on a scale of 0-3. This grade was then correlated with the Frisén Scale, an ophthalmologic scale used for grading papilledema from 0 (normal) to 5 (severe edema). To estimate the correlation between the MR imaging and Frisén scores, we calculated the Kendall τ coefficient. Forty-six patients (3 men, 43 women) with idiopathic intracranial hypertension and 61 controls (5 men, 56 women) with normal findings on MR imaging were included in this study. For both eyes, there was moderate correlation between the 2 scales (right eye: τ = 0.47; 95% CI, 0.31-0.57; left eye: τ = 0.38; 95% CI, 0.24-0.49). Interreader reliability for MR imaging scores showed high interreader reliability (right eye: κ = 0.76; 95% CI, 0.55-0.88; left eye: κ = 0.87; 95% CI, 0.78-0.94). Contrast-enhanced 3D-FLAIR imaging correlates with the Frisén Scale for moderate-to-severe papilledema and less so for mild papilledema. Hyperintensity of the optic nerve/optic nerve head on contrast-enhanced 3D-FLAIR is sensitive for the detection of papilledema in patients with idiopathic intracranial hypertension, which may be useful when prompt diagnosis is crucial.

Optical coherence tomography angiography features of optic nerve head drusen and nonarteritic anterior ischemic optic neuropathy

To evaluate the optic disc microvasculature in optic nerve head drusen (ONHD) vasculature in comparison to acute nonarteritic anterior ischemic optic neuropathy (NAION) and normal eyes using optical coherence tomography angiography (OCT-A). Ten eyes with ONHD, 10 eyes with acute NAION, and 10 healthy eyes were included in this prospective, comparative, observational case series. OCT-A imaging was performed on the optic discs. Qualitative grading was performed for dilation and tortuosity of the peripapillary vessels by 3 graders. Quantitative comparison was performed for peripapillary and inside disc vessel densities in nerve head (NH) and retinal peripapillary capillary (RPC) slabs. The intergrader agreement for dilation and tortuosity of the peripapillary vessels was poor (0.313 and 0.182 for vascular dilation in nerve head and radial peripapillary capillary enface images, respectively, and 0.478 and 0.490 for vascular tortuosity in nerve head and radial peripapillary capillary enface images, respectively). In NH en face images, the vessel density measurements were statistically significantly different between the 3 groups (all p < 0.05). In RPC en face images, the vessel density measurements were statistically significantly different between the 3 groups (all p < 0.05) except for nasal peripapillary sector (0.08). Despite poor intergrader agreement in qualitative analysis, quantitative OCT-A evaluation may differentiate optic disc edema due to NAION from pseudodisc edema due to ONHD.

Correlation of optic disc morphometry and optic disc microvasculature assessed with optical coherence tomography angiography

ObjectiveTo compare optic disc microvasculature measurements to the disc morphometrics in normal eyes. DesignCross-sectional study. ParticipantsFifty-eight healthy subjects. MethodsEnface 4.5x4.5 mm optical coherence tomography angiography images were obtained from the optic disc of healthy individuals. The radial peripapillary capillary (RPC) and the nerve head (NH) en face images were obtained. Also, spectral domain OCT measurements of the peripapillary nerve fibre layer (NFL) thickness were recorded. Correlations of the vessel density and NFL measurements with optic disc morphometrics were analyzed. ResultsFifty-eight eyes of 58 patients were included. Mean peripapillary NFL thickness was 99.77 ± 8.47 µm. The mean disc area was 2.15 ± 0.34 mm2 (range, 1.48–3.02 mm2) with an average cup/disc area ratio of 0.27 ± 0.14 (range, 0.0–0.6). On the RPC en face image, the mean vessel density of the whole image, peripapillary, and inside disc was 55.52 ± 2.90, 62.42 ± 3.30, and 45.77 ± 9.24%, respectively. On the NH en face images, the mean vessel density of the whole image, peripapillary, and inside disc was 55.69 ± 3.04, 60.15 ± 2.79, and 52.69 ± 5.31%, respectively. The NH vessel density in the inside disc area correlated with the cup/disc area ratio (R = −0.44, p < 0.001). The association of RPC vessel density in the inside disc area with the cup/disc area ratio was significant (R= −0.88, p < 0.001). The RPC vessel density in the peripapillary area correlated with the cup/disc area ratio (R = 0.37, p = 0.004). Also, the RPC vessel density in the whole image was associated with the peripapillary NFL thickness (R = 0.32, p = 0.01). ConclusionWe observed a significant negative correlation between inside disc vessel density and cup/disc area ratio, but not to the disc area in normal eyes. In addition, the whole image RPC vessel density was revealed to be weakly correlated with the average RNFL thickness.

Lamina Cribrosa Microarchitecture in Monkey Early Experimental Glaucoma: Global Change.

PurposeThe purpose of this study was to characterize experimental glaucoma (EG) versus control eye differences in lamina cribrosa (LC), beam diameter (BD), pore diameter (PD), connective tissue volume fraction (CTVF), connective tissue volume (CTV), and LC volume (LV) in monkey early EG.MethodsOptic nerve heads (ONHs) of 14 unilateral EG and 6 bilateral normal (BN) monkeys underwent three-dimensional reconstruction and LC beam segmentation. Each beam and pore voxel was assigned a diameter based on the largest sphere that contained it before transformation to a common cylinder with inner, middle, and outer layers. Full-thickness and layer averages for BD, PD, CTVF, CTV, and LV were calculated for each ONH. Beam diameter and PD distributions for each ONH were fit to a gamma distribution and summarized by scale and shape parameters. Experimental glaucoma and depth effects were assessed for each parameter by linear mixed-effects (LME) modeling. Animal-specific EG versus control eye differences that exceeded the maximum intereye difference among the six BN animals were considered significant.ResultsOverall EG eye mean PD was 12.8% larger (28.2 ± 5.6 vs. 25.0 ± 3.3 μm), CTV was 26.5% larger (100.06 ± 47.98 vs. 79.12 ± 28.35 × 106 μm3), and LV was 40% larger (229.29 ± 98.19 vs. 163.63 ± 39.87 × 106 μm3) than control eyes (P ≤ 0.05, LME). Experimental glaucoma effects were significantly different by layer for PD (P = 0.0097) and CTVF (P < 0.0001). Pore diameter expanded consistently across all PDs. Experimental glaucoma eye-specific parameter change was variable in magnitude and direction.ConclusionsPore diameter, CTV, and LV increase in monkey early EG; however, EG eye-specific change is variable and includes both increases and decreases in BD and CTVF.

Differential diagnosis of papilloedema

SummaryOptic disc swelling is a non‐specific manifestation of injury to the intraorbital portion of the optic nerve, the nerve head (or disc). By convention, the term “papilledema” refers to optic disc edema that is due to increased intracranial pressure. Increased intracranial pressure typically causes bilateral swelling of the optic discs, although asymmetry in the degree of disc edema is not uncommon. Truly unilateral papilledema is rare. In most cases of papilledema (increased intracranial pressure), visual function is relatively preserved. This lecture will present the differential diagnosis of patients who present with bilateral disc edema of unknown etiology and discuss how to distinguish those who have true papilledema of increased intracranial pressure.

Missing the 'window' might shut the light forever: Central retinal artery occlusion following spine surgery.

Missing the 'window' might shut the light forever: Central retinal artery occlusion following spine surgery.

Branches of the lower trunk neurotized by pre-vertebral route contralateral C7 nerve transfer as donor nerves: a preliminary study

Objective To explore the feasibility and effectiveness of using branches of the lower trunk on the affected side as donor nerves,i.e.medial brachial cutaneous nerve,medial antebrachial cutaneous nerve and posterior division of the lower trunk,after contralateral C7 nerve root transfer to the lower trunk via pre-vertebral route.Methods When the phrenic nerve and spinal accessory nerve were injured along with the brachial plexus,contralateral C7 nerve root was transferred to repair the lower trunk via pre-vertebral toute.Medial antebrachial cutaneous nerve of the affected side was again transferred to repair the musculocutaneous nerve,medial brachial cutaneous nerve transferred to repair the suprascapular nerve,posterior division of the lower trunk transferred to repair lateral head of the median nerve.A total of 14 cases of complete brachial plexus root avulsions were treated.Results Postoperatively 12 cases were follow-up for 24 to 65 months (mean,35 months).Average shoulder abduction reached 39°.Results in 67％ of the cases were considered effective (musele strength reached M2),and 58 ％ excellent (muscle strength reached M3).The average angle of elbow flexion was 77°,75％ rated effective and 58％ rated excellent.Finger and thumb flexion was restored to some extent.Finger flexor strength was ≥ M2 in 7 cases with an effective rate of 58 ％ and ≥ M3 in 5 cases with an excellent rate of 42％.Conclusion After being neurotized by the contralateral C7 nerve root via pre-vertebral route,branches of the lower trunk can be used as donor nerves to neurotize the musculocutaneous nerve,supraseapular nerve and lateral head of the median nerve. Key words: Brachial plexus; Nerve transfer; Microsurgery; Hand

Acute visual loss in a patient with optic disc drusen

Here we report a case of sudden, unilateral, painless visual loss in a middle-aged patient. A 45-year-old gentleman with no known past medical history presented with acute painless left visual impairment. Clinically, he was found to have a left optic neuropathy associated with a swollen and hyperemic left optic disc. The right optic disc was noted to be small and crowded, and both optic discs were noted to have irregular margins. Humphrey perimetry revealed a constricted visual field in the left eye. Fundus autofluorescence imaging revealed autofluorescence, and B-scan ultrasonography showed hyperreflectivity within both nerve heads. Blood investigations for underlying ischemic and inflammatory markers revealed evidence of hyperlipidemia but were otherwise normal. A diagnosis of left nonarteritic anterior ischemic optic neuropathy (NAAION) was made, with associated optic disc drusen and hyperlipidemia. NAAION typically occurs in eyes with small, structurally crowded optic discs. The coexistence of optic disc drusen and vascular risk factors may further augment the risk of developing NAAION.

Recurred Dislocation of Ulnar Nerve and Medial Head of Triceps Tendon

Recurred Dislocation of Ulnar Nerve and Medial Head of Triceps Tendon

Fast and automatic algorithm for optic disc extraction in retinal images using principle-component-analysis-based preprocessing and curvelet transform

Optic disc or optic nerve (ON) head extraction in retinal images has widespread applications in retinal disease diagnosis and human identification in biometric systems. This paper introduces a fast and automatic algorithm for detecting and extracting the ON region accurately from the retinal images without the use of the blood-vessel information. In this algorithm, to compensate for the destructive changes of the illumination and also enhance the contrast of the retinal images, we estimate the illumination of background and apply an adaptive correction function on the curvelet transform coefficients of retinal images. In other words, we eliminate the fault factors and pave the way to extract the ON region exactly. Then, we detect the ON region from retinal images using the morphology operators based on geodesic conversions, by applying a proper adaptive correction function on the reconstructed image's curvelet transform coefficients and a novel powerful criterion. Finally, using a local thresholding on the detected area of the retinal images, we extract the ON region. The proposed algorithm is evaluated on available images of DRIVE and STARE databases. The experimental results indicate that the proposed algorithm obtains an accuracy rate of 100% and 97.53% for the ON extractions on DRIVE and STARE databases, respectively.

Clinical application of Optovue RTVue OCI' and Heidelberg Retina Tomograph III in early diagnosis of glaucoma

Background Many studies showed that attenuation of retinal nerve fiber layer(RNFL)in early glaucoma is one of the important signs.How to accurately and quantitatively measure RNFL thickness is very important for the early diagnosis and monitoring of glaucoma.0bjective This study was to evaluate the clinical value of Optovue RTVue OCT and Heidelberg Retina Tomograph Ⅲ(HRT-Ⅲ)confocal scanning laser ophthalmoscopy in glaucomatous eyes. Methods This cross-sectional study included 40 eyes of 26 patients with suspected open-angle glaucoma(SOAG),48 eyes of 29 patients with open-angle glaucoma and 48 eyes of 27 healthy subjects.Optical nerve head(ONH) parameters and peripapillary RNFL thickness were measured in all the subjects with Optovue RTVue OCT and HRT-Ⅲ,meanwhile all the eyes received perimetry with Humphrey 750-I.Glaucoma variables obtained from Optovue RTVue OCT and HRT-Ⅲ were analyzed among the groups.Topographic Optovue RTVue OCT and HRT-Ⅲ parameters,including disc area(DA),cup area(CA),rim area(RA),rim volume(RV),cup volume(CV),cup/disc area ratio(C/DAR)as well as superior,temporal,inferior and nasal average RNFL thickness,were analyzed.The relationship of ONH parameters and RNFL thickness was analyzed using a linear correlation.The correlation between the mean defect(MD)of the visual field and the tomography parameters in glaucomatous eyes was described by bivariate Pearson correlation coefficients.Resuits The ONH parameters and RNFL thickness obtained by HRT-Ⅲ and OCT showed significant difference(P<0.05).ONH parameters such as RA,C/DAR,CA and RV were statistically changed in SOAG and the POAG patients compared with the normal subjects(q=6.47,q=7.67,P<0.05).The superior and inferior RNFL thickness parameters in three groups were positively correlated between HRT-Ⅲand OCT(r=0.362,r=0.441,r=0.395,P<0.05),Topographic Optovue RTVue OCT and HRT-Ⅲ parameters including CV,CA,RA and C/DAR fitted Pearson analysis(all P<0.05).In POAG group。The RA,RV,CV,C/DAR from Optovue RTVue OCT were correlated with MD with the significant coefficient 0.284,0.286,0.340,0.371 respectively(P<0.05),and evidently correlations also were found between RA,RV,C/DAR with MD respectively with the coefficient 0.339,0.859,0.422(P<0.05)by HRT-Ⅲ. Conclusion Both Optovue RTVue OCT and HRT-Ⅲ can difierentiate ONH analysis with a similar outcome in glaucomatous eye.The C/D value.RA,superior and inferior RNFL thickness based on Optovue RTVue OCT and HRT-Ⅲare distinguishing indexes in the diagnosis of early glaucomatous damage. Key words: Glaucoma; Optovue RTVue OCT; Heidelberg Retina Tomograph Ⅲ confocal scanning laser ophthalmoscopy; Retinal nerve fiber layer thickness; Optical disc; Perimetry

Differential effects of tamoxifen and anastrozole on optic cup size in breast cancer survivors

IntroductionThe main purpose of this study was to determine whether the optic cups of tamoxifen users and anastrozole users differ in size, with the cups of the tamoxifen users being smaller.MethodsOptic nerve head (ONH) topography was measured using a commercially available, confocal scanning laser ophthalmoscope for three populations of amenorrheic women ages 40–69 years: subjects using (1) tamoxifen (20 mg/day) or (2) anastrozole (1 mg/day) for ≤ 2 years as adjuvant therapy after successful primary treatment for breast cancer, and (3) control subjects with no breast cancer histories and not using any hormonal medication. All subjects had excellent visual acuity and healthy eyes, based on conventional photographic assessment.ResultsThe cup volumes of the tamoxifen users were shown to be significantly smaller than the cup volumes of the anastrozole users, which were indistinguishable from normal. Because the cup volumes of the tamoxifen users decreased markedly with age at about 50 years and because anastrozole is indicated only for post-menopausal women, comparisons were reassessed for subjects older than 50 years. For these subjects, the cup volumes of the tamoxifen users averaged less than half of the volumes for each of the other two subject groups, and significant between-group differences existed in both the lateral (cup area) and axial (cup depth) directions. In contrast, any between-group differences at the ONH margin were small and not significant.ConclusionsThe results of this study suggest that the ONH be assessed biomorphometrically for tamoxifen users reporting visual change that cannot be attributed to non-tamoxifen causes. The ability of modern intraocular imaging techniques to reveal anatomic change on the order of tens of microns may be useful for assessing tamoxifen-induced effects occurring simultaneously elsewhere in the brain, particularly since the presence of small cups is consistent with the possibility of tamoxifen-induced astrocytic swelling.

Pharmacological Neuroprotection for Glaucoma

Glaucoma represents a group of neurodegenerative diseases characterised by structural damage to the optic nerve and slow, progressive death of retinal ganglion cells (RGCs). Elevated intraocular pressure is traditionally considered to be the most important risk factor for glaucoma, and treatment options for the disease have hitherto been limited to its reduction. However, visual field loss and RGC death continue to occur in patients with well controlled intraocular pressures and, thus, a consensus has recently emerged that additional treatment strategies are needed. One such strategy is pharmacological neuroprotection, which in the context of glaucoma, refers to the situation in which a drug is deployed to interact with neuronal or glial elements within the retina/optic nerve head and thereby facilitate the survival of RGCs. The advent of animal models of chronic glaucoma has enhanced our understanding of many of the pathological processes occurring in glaucoma and, in doing so, described logical targets for pharmacological intervention. Such targets, which have been manipulated with varying degrees of success in relevant animal paradigms include glutamate receptors, autoimmune elements, neurotrophin deprivation, nitric oxide synthesis, oxidative stress products, sodium and calcium channels, heat shock proteins and apoptotic pathways. With exciting data now emerging from many research laboratories, it is obvious that pharmacological neuroprotection for glaucoma without doubt represents an exciting development in the search for a treatment modality for this debilitating disease.

Retinal nerve fiber layer thickness in unilateral amblyopia.

To test the hypothesis that eyes with amblyopia may have thicker retina, retinal nerve fiber layer thickness (RNFLT) was investigated in patients with unilateral amblyopia. Thirty-eight patients with unilateral amblyopia were studied. Among them, 20 patients had amblyopia with strabismus and 18 had refractive amblyopia without strabismus. Nineteen of 38 had anisometropia of 2.0 D or more. In addition, 17 patients with anisometropia of 2.0 D or more but without amblyopia were enrolled as control subjects. RNFLT was measured by optical coherence tomography with scan pattern "Nerve Head 2.0R" (Carl Zeiss Meditec, Dublin, CA). Average RNFLT was multiplied with their corresponding scan circumferences to estimate the integral values of the total RNFL area (RNFLT(estimated integrals)). In all 38 patients with unilateral amblyopia, the difference in RNFLT and in RNFLT(estimated integrals) between the amblyopic eyes and the normal fellow eyes were statistically significant. Multivariate regression analysis with adjustment for axial length, spherical equivalence, age, and sex indicated significant differences as well. In the group of strabismic amblyopia, the difference in RNFLT and in RNFLT(estimated integrals) between the amblyopic eyes and the normal fellow eyes did not reach statistical significance. However, in the group of refractive amblyopia, the difference in RNFLT and in RNFLT(estimated integrals) between the amblyopia eyes and the normal fellow eyes both had a statistical significance. In the 19 patients with anisometropic amblyopia, the difference in RNFLT and in RNFLT(estimated integrals) between the amblyopic eyes and the normal fellow eyes were statistically significant. In the control group of 17 patients with nonamblyopic anisometropia, the difference in RNFLT and in RNFLT(estimated integrals) between both eyes did not reach statistical significance. RNFLT may be affected by refractive amblyopia, but further histopathologic confirmation is needed.

A Case of Optic Nerve Drusen Associated with Grönblad-Strandberg Syndrome

We report a rare case of optic nerve drusen associated with Grönblad-Strandberg syndrome. The patient was a 29-year-old woman who had pseudoxanthoma elasticum on her neck. On eye examination, there were no abnormal findings in the anterior segment or ocular media. Ophthalmoscopic examination revealed milky white granular lesions on the optic nerve disc, and angioid streaks around the disc in both eyes. Orbital computerized tomography(CT), B-scan echography and photography with a fluorescein angiography filter identified the granular lesions as optic nerve drusen. With a scanning laser ophthalmoscope(SLO), poorly-visible drusen buried below the nerve head could be detected. The optic nerve drusen could be seen more clearly by infrared laser than by helium-neon laser. SLO using infrared laser is useful for evaluation of superficial and buried drusen.