Relationship between nailfold capillaroscopy parameters and the severity of diabetic retinopathy.

PURPOSE: To determine whether non-invasive measurements of the nailfold capillaries (NCs) are associated with the presence and severity of diabetic retinopathy (DR) in patients with type 2 diabetes. METHODS: Eighty-three eyes of 83 patients with type 2 diabetes were enrolled. Sixty-three age-matched non-diabetic subjects served as controls. Diabetic patients were classified by the severity of their DR: non-DR (NDR), non-proliferative DR (NPDR), and proliferative DR (PDR). We used nailfold capillaroscopy to measure NC parameters, including number, length, width, and turbidity. RESULTS: Four NC parameters in the diabetic patients were significantly lower than in the controls (all P < 0.001). There was a statistically significant decrease in the NC parameters along with the increasing severity of DR (number: P = 0.02; all others: P < 0.001). Logistic regression analysis revealed that combining the systemic characteristics of age, sex, systolic blood pressure, estimated glomerular filtration rate, hemoglobin A1c level, and history of hypertension and dyslipidemia could indicate the presence of DR and PDR (the area under the receiver operating characteristic curve [AUC] = 0.81, P = 0.006; AUC = 0.87, P = 0.001, respectively). Furthermore, the discriminative power of DR was significantly improved (P = 0.03) by adding NC length to the systemic findings (AUC = 0.89, P < 0.001). CONCLUSION: NC measurement is a simple and non-invasive way to assess the risk of DR and its severity.

Changes in ocular blood flow in patients with neovascular age-related macular degeneration after intravitreal injection of ranibizumab biosimilar and brolucizumab.

PURPOSE: To assess ocular blood flow (OBF) changes in patients with neovascular age-related macular degeneration (nAMD) treated with intravitreal injections of ranibizumab biosimilar (IVRbs) or brolucizumab (IVBr). METHODS: This retrospective longitudinal study included 43 eyes of 43 patients (74.5 ± 9.8 years old, male to female ratio 31:12) with nAMD treated with IVBr (29 eyes) or IVRbs (14 eyes). OBF in the optic nerve head (ONH) and choroid (Ch) was measured with laser speckle flowgraphy (Softcare Co., Ltd., Fukutsu, Japan) before and one month after treatment. Changes in mean blur rate (MBR) before and after each treatment were tested using Wilcoxon's signed-rank tests and mixed-effect models for repeated measures. RESULTS: In the IVBr group, MBR was significantly reduced in both the ONH and Ch (p < 0.01). In contrast, the IVRbs group showed no significant change in MBR in either the ONH or Ch (p = 0.56, p = 1). The linear mixed effect model showed a significant interaction between time and anti-VEGF drugs for MBR in both the ONH and Ch (ONH: p = 0.04; Ch: p = 0.002). A post hoc pairwise comparison of estimated marginal means showed that MBR decreased significantly only after IVBr (p < 0.001). CONCLUSION: Our findings suggest that the short-term impact on OBF varies depending on the drug used for nAMD.

Vasoreactivity of the optic nerve head, nailfold, and facial skin in response to cold provocation in normal-tension glaucoma patients.

BACKGROUND: The dysfunction of optic nerve head (ONH) hemodynamics has been suggested to be involved in the pathogenesis of normal-tension glaucoma (NTG). The aim of this study was to compare vasoreactivity in the ONH, nailfold, and facial skin in response to cold-water provocation in NTG patients and healthy controls. METHODS: We performed cold-water provocation in 14 eyes of 14 NTG patients and 15 eyes of 15 age-matched control subjects. Laser speckle flowgraphy-derived tissue-area mean blur rate (MT), skin blood flowmetry-derived pulse wave amplitude (PA), nailfold capillaroscopy-derived nailfold capillary diameter, and other clinical parameters were recorded at baseline and 4 and 6 min after the cold stimulus. We compared changes (as percentages) in these variables in the NTG and control subjects with a linear mixed-effects model and evaluated correlations between these changes with Spearman's rank correlation coefficient. RESULTS: The interaction term between the NTG group (reference, control group) and the 4-min protocol step (reference, baseline) significantly affected the changes in MT, nailfold capillary diameter and PA (ß = -9.51%, P = 0.017, ß = -20.32%, P = 0.002; ß = + 18.06%, P = 0.017, respectively). The change in MT was positively correlated with the change in nailfold capillary diameter, and negatively correlated with the change in PA (r = 0.39, P = 0.036; r = -0.40, P = 0.031, respectively). CONCLUSION: NTG patients showed abnormal vasoconstriction in the ONH and nailfold and vasodilation in the facial skin in response to cold-water provocation.

Baseline characteristics associated with the incidence of intraocular inflammation after the intravitreous injection of brolucizumab.

PURPOSE: To investigate baseline characteristics associated with the incidence of intraocular inflammation (IOI) after the intravitreal injection of brolucizumab (IVBr) for the treatment of neovascular age-related macular degeneration (nAMD). METHODS: This retrospective study included 66 eyes of 62 consecutive patients with nAMD who received IVBr (18 eyes were treatment naïve and 48 eyes had switched from other anti-vascular endothelial growth factor [VEGF] therapy). Baseline clinical characteristics were compared in non-IOI and IOI groups. RESULTS: Although a dry macula was achieved at a high rate even 6 months after IVBr, IOI occurred in 8 of 66 eyes (12.1%; all had switched therapy) during the study period. Baseline characteristics including age, sex, nAMD type, lens status, visual acuity, central macular thickness, and a history of diabetes did not differ between the groups. The number of previous anti-VEGF injections before IVBr was greater in the IOI group (P = 0.004), and the ratio of patients with a laser flare-cell photometry (LFCP) value over 15 photon count per millisecond (pc/ms) was higher in the IOI group (P = 0.017). Multivariate logistic regression analysis showed that a greater number of previous anti-VEGF injections (odds ratio [OR]: 1.12, P = 0.006; area under the curve: 0.82, cut-off score: 14.0) and an LFCP value over 15 pc/ms (OR: 81.6, P = 0.031) were significantly associated with the incidence of IOI after IVBr. CONCLUSION: A number of previous anti-VEGF injections greater than 14 and an LFCP value more than 15 pc/ms might be useful predictors of the incidence of IOI after IVBr in eyes with nAMD.

RETINAL SENSITIVITY AND VESSEL DENSITY AFTER MACULAR HOLE SURGERY WITH THE SUPERIOR INVERTED INTERNAL LIMITING MEMBRANE FLAP TECHNIQUE.

PURPOSE: To evaluate retinal vessel density and retinal sensitivity (RS) after macular hole surgery with the superior inverted internal limiting membrane flap technique. METHODS: Retrospective, observational case series. Twenty-one patients with idiopathic macular hole underwent 27-gauge vitrectomy with the superior inverted internal limiting membrane flap technique and triamcinolone acetonide. Measurements included RS, which was measured with microperimetry, as well as retinal vessel density in the superficial capillary plexus (SCP) and deep capillary plexus (DCP), which was measured with optical coherence tomography angiography. All parameters were evaluated in the superior and inferior sectors of the macula preoperatively and 1, 3, and 6 months postoperatively. RESULTS: Six months postoperatively, retinal thickness in the inferior sector was unchanged, but retinal thickness in the superior sector decreased significantly (P < 0.01). SCP vessel density in both sectors was unchanged at all postoperative time points. DCP vessel density in both sectors increased very significantly at 3 months (P < 0.01) and returned to baseline at 6 months. RS in the inferior sector increased by 47% 3 months postoperatively and by 61% 6 months postoperatively (P < 0.05 and P < 0.001, respectively), but RS in the superior sector increased only at 6 months postoperatively and only by 22% (P < 0.05). CONCLUSION: Lower recovery of RS in the superior sector suggests that internal limiting membrane peeling might affect the postoperative visual function.

Ocular microcirculation changes, measured with laser speckle flowgraphy and optical coherence tomography angiography, in branch retinal vein occlusion with macular edema treated by ranibizumab.

PURPOSE: This study searched for early predictive vascular biomarkers for visual outcomes in eyes with macular edema caused by branch retinal vein occlusion (BRVOME). METHODS: Twenty-four eyes of 24 subjects with BRVOME were treated with the intravitreal injection of ranibizumab (IVR) for at least 6 months. We measured mean blur rate (MBR) in the optic nerve head (ONH) and vessel density (VD) in the macula with laser speckle flowgraphy and optical coherence tomography angiography, respectively. RESULTS: Six-month post-IVR best-corrected visual acuity (BCVA) was correlated positively with age, pre-IVR BCVA, 1-month post-IVR BCVA, 3-month post-IVR BCVA and pre-IVR systolic blood pressure (P < 0.001, P < 0.001, P < 0.001, P < 0.001 and P = 0.02, respectively) and negatively with pre-IVR overall MBR, 1-month post-IVR overall MBR, 6-month post-IVR overall MBR, 3-month post-IVR deep retinal capillary plexus (DCP) VD and 6-month post-IVR DCP VD (P = 0.03, P = 0.03, P = 0.02, P = 0.01 and P = 0.005, respectively). Furthermore, a multiple regression analysis showed that pre-IVR overall MBR (ß = - 0.67, P = 0.009) was among independent prognostic factors predicting 6-month post-IVR BCVA. Six-month post-IVR DCP VD was also correlated with overall MBR at all time points. CONCLUSION: ONH blood flow may be a pre-IVR biomarker of both visual outcomes and post-IVR deep macular microcirculation in eyes with BRVOME.

Companion Diagnosis for Retinal Neuroprotective Treatment by Real-Time Imaging of Calpain Activation Using a Novel Fluorescent Probe.

Calpain activation induces retinal ganglion cell (RGC) death, while calpain inhibition suppresses RGC death, in animal studies. However, the role of calpain in human retinal disease is unclear. This study investigated a new strategy to study the role of calpain based on real-time imaging. We synthesized a novel fluorescent probe for calpain, acetyl-l-leucyl-l-methionine-hydroxymethyl rhodamine green (Ac-LM-HMRG) and used it for real-time imaging of calpain activation. The toxicity of Ac-LM-HMRG was evaluated with a lactate dehydrogenase cytotoxicity assay, retinal sections, and electroretinograms. Here, we performed real-time imaging of calpain activation in a rat model. First, we administered N-methyl-d-aspartate (NMDA) to induce retinal injury. Twenty minutes later, we administered an intravitreal injection of Ac-LM-HMRG. Real-time imaging was then completed with a noninvasive confocal scanning laser ophthalmoscope. The inhibitory effect of SNJ-1945 against calpain activation was also examined with the same real-time imaging method. Ac-LM-HMRG had no toxic effects. The number of Ac-LM-HMRG-positive cells in real-time imaging significantly increased after NMDA injury, and SNJ-1945 significantly lowered the number of Ac-LM-HMRG-positive cells. Real-time imaging with Ac-LM-HMRG was able to quickly quantify the NMDA-induced activation of calpain and the inhibitory effect of SNJ-1945. This technique, used as a companion diagnostic system, may aid research into the development of new neuroprotective therapies.

Association of retinal vessel density with retinal sensitivity in surgery for idiopathic epiretinal membrane.

PURPOSE: The success of surgical treatment for idiopathic epiretinal membrane (ERM) is measured by postoperative best-corrected visual acuity (BCVA), metamorphopsia, and foveal retinal sensitivity (RS).This study searched for predictive biomarkers of surgical success by determining the association between foveal RS and various aspects of vessel density (VD) in the fovea of patients with ERM. METHODS: The study examined 25 eyes of 25 patients with ERM who underwent 27-gauge microincision vitrectomy surgery (MIVS). RS was measured with microperimetry (MP-3; NIDEK) at four central points in the fovea with an interpoint distance of 2°. VD was measured with SD-OCT (RS 3000; NIDEK) within the 1-mm2 square defined by the 4 RS points at various depths, including the superficial and deep retinal capillary plexus (SCP and DCP, respectively). RESULTS: Though VD did not change throughout the follow-up period, BCVA and RS significantly improved 1 and 3 months after surgery, respectively (both P < 0.0017). Postoperative RS at 6 months was positively correlated with postoperative DCP VD at 1, 3, and 6 months (r = 0.62, P = 0.001; r = 0.40, P = 0.049; r = 0.53, P = 0.007, respectively), but not with SCP VD at any time point. Multiple regression analysis confirmed that postoperative RS at 6 months was associated with postoperative DCP VD at 1 month (P = 0.03). CONCLUSION: Higher postoperative DCP VD at 1 month contributed to better postoperative foveal RS at 6 months. Early postoperative VD in the fovea might be a useful predictive biomarker of late postoperative RS in the fovea in ERM patients.

Endogenous endophthalmitis caused by group B streptococcus; case reports and review of 35 reported cases.

BACKGROUND: Group B streptococcus (GBS), a gram-positive coccus that occasionally causes neonatal sepsis or invasive infection in the elderly, has been considered a rare cause of endogenous bacterial endophthalmitis (EBE). However, the number of invasive GBS infections is increasing, particularly in elderly patients with underlying conditions such as diabetes mellitus (DM), cardiovascular disease and cancer. We report 6 cases of EBE caused by GBS and review the literature. METHODS: Retrospective case series and literature review. RESULTS: In the current case series, 6 eyes of 6 patients developed EBE caused by GBS. The average age was 73.5 years. The focus of infection included the urinary tract, cellulitis, arthritis, peritonitis, catheter-associated infection and endocarditis. Four patients had DM. While all 6 strains were sensitive to ß-lactams (penicillins and cephems), 4 strains were resistant to levofloxacin (no data for 1 isolate). Each case was treated with the systemic antibiotic to which the individual strain was sensitive. All cases showed poor visual acuity at presentation (decimal visual acuity: less than 0.03). Vitrectomy with intravitreal antibiotics injection was performed in 4 cases. Visual acuity recovered in 4 cases and did not recover in 2 cases, even after vitrectomy. The literature review of 53 eyes of 41 patients revealed that 60% of eyes finally lost all vision, and death occurred in 2 cases. Initial visual acuity of less than counting fingers was associated with a final outcome of lost vision. Of 41 patients, 13 (32%) had DM as an underlying medical condition. The most common extra-ocular infection focus was endocarditis (37%). CONCLUSIONS: DM is common in patients with EBE caused by GBS. While the 4 cases in the current report had a relatively good visual acuity outcome, despite poor initial visual acuity, the literature review indicated that EBE caused by GBS is generally a severe condition with a poor prognosis. The current study also indicates the importance of considering the possibility of endocarditis on encountering EBE caused by GBS.

Association of CRX genotypes and retinal phenotypes confounded by variable expressivity and electronegative electroretinogram.

IMPORTANCE: A framework for understanding the phenotypic features of CRX retinopathy was established. BACKGROUND: To perform a phenotype-genotype correlation analysis in two groups of patients with heterozygous mutations in distinct locations of the CRX gene, encoding the cone-rod homeobox. DESIGN: Multicentre retrospective study. PARTICIPANTS: Twenty-one Japanese patients from 14 families with a heterozygous CRX mutation. METHODS: Retrospective data analysis. MAIN OUTCOME MEASURES: Clinical records on CRX mutation, symptoms, best-corrected visual acuity (BCVA), visual field, fundus photography, fundus auto-fluorescence, optical coherence tomography and electroretinograms (ERGs). RESULTS: Six different CRX heterozygous mutations were identified in the subjects. Twelve patients from 9 families shared the p.R41W mutation and 1 patient had the p.R43C mutation, both of which affect the homeobox domain of CRX. These patients often displayed adult-onset retinal dystrophy with macular degeneration. In contrast, five patients with downstream mutations (p.S204fs, p.S213fs, p.G243X and p.L299F) displayed retinal degeneration or macular degeneration with bone-spicule pigmentation. Three asymptomatic carriers with different mutations (p.R41W, p.S213fs and p.G243X) were present in both groups. Nearly all patients and carriers had an electronegative ERG in response to a bright flash under dark adaptation. There was no cross-sectional association between patients' age and BCVA, despite progressive decline in BCVA. CONCLUSIONS AND RELEVANCE: Heterozygous mutations within or downstream of the homeobox domain in CRX relate to the difference associated retinal phenotypes, which was confounded by variable expressivity and electronegative ERGs. CRX mutations should be considered in patients with an electronegative ERG with minimal or no macular changes.

Phenotypic Features of Oguchi Disease and Retinitis Pigmentosa in Patients with S-Antigen Mutations: A Long-Term Follow-up Study.

PURPOSE: To present phenotypic features of 22 patients with S-antigen (SAG) mutations. DESIGN: Retrospective cohort study. PARTICIPANTS: Twenty-one Japanese patients from 16 families with a homozygous c.924delA mutation and 1 patient with a homozygous c.636delT mutation in the SAG gene. METHODS: Clinical records on symptoms; best-corrected visual acuity; and Goldmann perimetry, fundus photography, fundus autofluorescence (FAF), OCT, and electroretinography results were reviewed. MAIN OUTCOME MEASURES: Best-corrected visual acuity, Goldmann perimetry results, imaging findings, and electroretinography results. RESULTS: Ten patients had Oguchi disease and 12 had retinitis pigmentosa (RP) with mean follow-up periods of 13.8 and 10.2 years, respectively. Retinitis pigmentosa patients were older (mean age, 56.0 years) than those with Oguchi disease (mean age, 22.1 years; P < 0.001) at the initial visit. Night blindness noted in childhood was the most common initial symptom for both Oguchi disease (80.0%) and RP (91.7%) patients. Best-corrected visual acuity in the logarithm of the minimum angle of resolution (logMAR) was well preserved in Oguchi disease patients (mean, 0.02 logMAR in both eyes) but reduced in most RP patients (mean, 1.32 logMAR [right eye] and 1.35 logMAR [left eye]). Similarly, the visual field in the retinal area was preserved in Oguchi disease patients (mean, 677 mm2 right eye and 667 mm2 left eye) and reduced in RP patients (mean, 369 mm2 right eye and 294 mm2 left eye). Fundus images revealed a characteristic golden sheen with no retinal degeneration in Oguchi disease patients, excluding 2 with macular degeneration detected by FAF, OCT, or both and 1 with mild retinal degeneration confirmed by OCT and fluorescein angiography. Pigmentary retinal degeneration most evident posteriorly was observed in RP patients, accompanied by a characteristic golden sheen in 12 of 14 patients undergoing ultra-widefield fundus imaging. OCT showed disrupted macular structure, and FAF revealed variable hypofluorescence. Electroretinography identified absent rod responses in both diseases, along with relative preservation of cone responses in Oguchi disease patients. Three patients showed progressive loss of the golden sheen based on fundus images, including 1 who demonstrated RP 26 years after the initial diagnosis of Oguchi disease. CONCLUSIONS: Retinitis pigmentosa with SAG mutations often shows a characteristic golden sheen surrounding posterior pigmentary retinal degeneration. Oguchi disease can show progressive degeneration in adulthood, rarely resulting in RP.

Historical, Current and Future Approaches to Surgery for Rhegmatogenous Retinal Detachment.

Rhegmatogenous retinal detachment (RRD) is a serious condition that can cause blindness without surgical treatment. RRD occurs when a retinal tear or hole allows fluid to accumulate below the retinal surface, causing the retina to separate from the underlying layers. RRD is difficult to treat because each case is unique, varying with the location, size, and duration of the detachment, as well as patient age. The first successful methods to reattach the retina in RRD used thermocautery to repair the detachment. Many renowned ophthalmologists continued to study RRD and developed many new surgical approaches, notably: scleral buckling (SB), in which a silicone band is placed around the eye to reduce traction on the retina caused by the vitreous humor that fills the eye; pars plana vitrectomy (PPV), which eliminates traction on the retina by removing the vitreous; and pneumatic retinopexy (PR), in which the retina is reattached by pushing it back into place with an expanding gas bubble injected into the eye. However, no consensus has been reached on which approach is ideal. Furthermore, recent surgical and non-surgical breakthroughs, such as artificial vitreous substitutes and neuroprotective drugs, must also be considered. Thus, this review provides a guide for ocular specialists and non-specialists on the historical background of RRD, summarizes the three current main techniques (SB, PR and PPV) compares these three techniques, and provides an overview of new technologies that promise to greatly improve outcomes after RRD surgery.

Endogenous Fusarium Endophthalmitis During Treatment for Acute Myeloid Leukemia, Successfully Treated with 25-Gauge Vitrectomy and Antifungal Medications.

Endogenous fungal endophthalmitis (EFE) caused by disseminated fusariosis is a rare condition that generally has a poor outcome, even with intensive therapy. Here, we describe a case in which this type of EFE was diagnosed with vitreous sampling and was successfully treated with 25-gauge vitrectomy and antifungals, including liposomal amphotericin B and voriconazole. A 16-year-old male patient undergoing treatment for acute myeloid leukemia complained of eye pain and blurred vision in his right eye. Treatment was initiated for a vitreous opacity, possibly associated with herpetic retinitis, but the patient worsened and he was referred to us. Right-eye visual acuity was limited to light perception. We suspected endogenous endophthalmitis and performed 25-gauge vitrectomy with antibiotic perfusion of ceftazidime, vancomycin, and voriconazole. Vitreous culturing revealed the presence of Fusarium solani species complex, and enhanced computed tomography revealed disseminated fusariosis lesions in the lung, spleen, and the soft tissue of the left upper arm. The patient received antifungal treatment with liposomal amphotericin B and voriconazole, and these conditions were eliminated. Visual acuity recovered to 20/400 after additional vitrectomy for tractional retinal detachment and was maintained at this level during the 6-month follow-up period. The success of our treatment allowed the capture of optical coherence tomography images of the retina during fusarium-associated endogenous endophthalmitis and the follow-up period. Furthermore, this case showed that immediate vitrectomy for suspected EFE and intensive treatment can lead to a good clinical outcome.

Endophthalmitis associated with Purpureocillium lilacinum during infliximab treatment for surgically induced necrotizing scleritis, successfully treated with 27-gauge vitrectomy.

PURPOSE: To report a case of endophthalmitis associated with Purpureocillium lilacinum (P. lilacinum) during infliximab treatment for surgically induced necrotizing scleritis, successfully treated with 27-gauge vitrectomy. METHODS: A single case report. RESULTS: A 71-year-old man who had undergone immunosuppressive therapy, including infliximab, for surgically induced necrotizing scleritis (SINS) in his left eye complained of visual disturbance and eye pain in the eye. He had a past history of surgery for recurrent pterygium: pterygium excision, amnion transplantation with mitomycin C and limbal transplantation. Visual acuity in the left eye was counting fingers at 30 cm, and intraocular pressure was 3.0 mmHg. Slit-lamp examination revealed the presence of anterior chamber cells (3+), and a B-mode ultrasound scan showed a vitreous opacity. We made a diagnosis of endophthalmitis and performed 27-gauge microincision vitrectomy surgery (27GMIVS) with antibiotic perfusion of ceftazidime, vancomycin and voriconazole. Intraoperative findings included a fungus-like ball-shaped opacity in the vitreous, and a close-to-normal retinal appearance. A vitreous body culture identified the presence of P. lilacinum. After 2 months of antibacterial and antifungal therapy, inflammation decreased and visual acuity recovered to 20/100. CONCLUSIONS: This is the first report of a case of endophthalmitis associated with P. lilacinum during infliximab treatment for SINS. Scleral thinning due to necrotizing scleritis, especially during immunosuppressive therapy, is a risk factor for endophthalmitis. We found that 27GMIVS was a useful strategy for such a challenging clinical situation.

Relationship between laser speckle flowgraphy and optical coherence tomography angiography measurements of ocular microcirculation.

PURPOSE: The purpose of this study was to investigate the relationship between laser speckle flowgraphy (LSFG) and optical coherence tomography angiography (OCTA) measurements of ocular microcirculation in normal and open-angle glaucoma (OAG) subjects. METHODS: This study included 18 eyes of 18 OAG patients and ten eyes of ten age-matched healthy controls. LSFG was used to measure mean blur rate (MBR) in the optic nerve head (ONH) vessel area (MV) and tissue area (MT). OCTA was used to measure a new parameter, peripapillary relative intensity (PRI), in the superficial retina, superficial choroid, and deep choroid. Statistical associations were then determined. RESULTS: MV, MT, superficial-retinal PRI, and superficial-choroidal PRI were lower in the OAG subjects than the controls (P = 0.02, P < 0.001, P = 0.02 and P = 0.008, respectively). Superficial-retinal PRI was correlated with MV and MT (R = 0.68, P < 0.001 and R = 0.63, P < 0.001, respectively). Superficial-choroidal PRI was also correlated with MV and MT (R = 0.45, P = 0.02 and R = 0.57, P = 0.002, respectively). Multiple regression analysis revealed that MV and MT independently contributed to superficial-retinal PRI (P = 0.008 and P = 0.04, respectively), while only MT contributed to superficial-choroidal PRI (P = 0.03). CONCLUSIONS: Our finding that OCTA-measured PRI was related to LSFG-measured MBR was reasonable, considering the vascular anatomy of the eye. Thus, PRI, like MBR, may be a promising biomarker of ocular microcirculation that can reveal the presence of ocular diseases such as OAG.

Real-time imaging of RGC death with a cell-impermeable nucleic acid dyeing compound after optic nerve crush in a murine model.

The retinal ganglion cells (RGCs) are the main source of therapeutic targets for neuroprotective glaucoma treatment, and evaluating RGCs is key for effective glaucoma care. Thus, we developed a minimally invasive, quick, real-time method to evaluate RGC death in mice. In this article we describe the details of our method, report new results obtained from C57BL/6J mice, and report that our method was usable in wild type (WT) and knockout (KO) mice lacking an RGC-death-suppressing gene. It used a non-invasive confocal scanning laser ophthalmoscope (cSLO) and a low molecular weight, photo-switching, cell-impermeant, fluorescent nucleic acid dyeing compound, SYTOX orange (SO). The RGCs were retrogradely labeled with Fluorogold (FG), the optic nerve was crushed (ONC), and SO was injected into the vitreous. After ten minutes, RGC death was visualized with cSLO in vivo. The retinas were then extracted and flat mounted for histological observation. SO-labeled RGCs were counted in vivo and FG-labeled RGCs were counted in retinal flat mounts. The time course of RGC death was examined in Calpastatin KO mice and wild type (WT) mice. Our in vivo imaging method revealed that SO-positive dead RGCs were mainly present from 4 to 6 days after ONC, and the peak of RGC death was after 5 days. Moreover, the number of SO-positive dead RGCs after 5 days differed significantly in the Calpastatin KO mice and the WT mice. Counting FG-labeled RGCs in isolated retinas confirmed these results. Thus, real-time imaging with SO was able to quickly quantify ONC-induced RGC death. This technique may aid research into RGC death and the development of new neuroprotective therapies for glaucoma.