Morphologic Changes in the Lamina Cribrosa Upon Intraocular Pressure Lowering in Patients With Normal Tension Glaucoma.

Purpose: The purpose of this study was to investigate whether the lamina cribrosa (LC) curve changes in response to intraocular pressure (IOP) reduction following administration of topical ocular hypotensive eye drops in eyes with normal tension glaucoma (NTG). Methods: Ninety-three eyes of 93 patients with treatment naïve NTG at initial examination and with ≥20% reduction from baseline IOP following administration of topical ocular hypotensive eye drops were included. Serial horizontal B-scan images of the optic nerve head (ONH) were obtained from each eye using enhanced depth imaging spectral domain optical coherence tomography (OCT) before and 1 year after IOP-lowering treatment. The LC curvature in each eye was assessed by measuring the LC curvature index (LCCI) in horizontal OCT B-scan images obtained at three (superior, central, and inferior) locations spaced equidistantly across the vertical optic disc diameter before and after IOP-lowering treatment. We evaluated the OCT detectible change in the LC curvature based on the interval change of LCCI to exceed the intersession standard deviation of 1.96 times and factors associated with the magnitude of the LCCI change in the eyes showing significant LC change. Results: IOP decreased from 15.7 ± 2.5 mm Hg at baseline to 11.2 ± 1.7 mm Hg after topical glaucoma medication. Among the 93 subjects, 62 (66.7%) eyes showed the significant reduction of the LCCI (interssetional change over 1.5) after the treatment; greater interssessional change of the LCCI after IOP reduction was associated with younger age (P = 0.020) and larger baseline LCCI (P < 0.001). Conclusions: The OCT detectible changes in LC curvature occurred in response to a modest decrease in the IOP in the naïve NTG eyes. The therapeutic benefit of these changes need to be assessed in longitudinal studies.

Longitudinal Observation of Border Tissue Configuration During Axial Elongation in Childhood.

Purpose: To investigate the change of border tissue configuration during axial elongation in childhood. Methods: Fifty-four subjects (108 eyes; age range, 29.3-132.5 months) who had undergone a series of swept-source optical coherence tomography scans at intervals of 6 months or longer were classified into stable axial length (AXL) eyes (n = 55; AXL change of ≤0.36 mm) and elongating AXL eyes (n = 53; AXL change of >0.36 mm). The angle between the Bruch's membrane opening (BMO) reference plane and the border tissue of Elschnig was defined as the border tissue angle (BTA). The border tissue angle, BMO distance (BMOD) and minimum rim width (MRW) were measured in the temporal and nasal regions. Results: During 15.6 ± 7.2 months of follow-up, the AXL significantly increased from 22.8 ± 1.3 mm to 23.3 ± 1.4 mm (P < 0.001). Changes of border tissue angle and AXL showed a significant correlation only in the temporal region of elongating AXL eyes (r = -0.409; P = 0.002), but not in stable AXL eyes. Both BMOD and nasal MRW significantly increased from 1482.5 ± 153.0 to 1506.1 ± 154.6 µm and from 310.6 ± 83.2 to 324.6 ± 95.6 µm, respectively (all Ps < 0.001). The changes of BMOD and nasal MRW showed a significant positive correlation with changes of AXL in elongating AXL eyes but not in stable AXL eyes. Conclusions: During the axial elongation in childhood, temporal border tissue configuration change, BMO enlargement, and nasal peripapillary tissue elevation showed a significant correlation with changes in the AXL.

Deep optic nerve head morphology and glaucoma progression in eyes with and without laminar dot sign: a longitudinal comparative study.

PURPOSE: To investigate the association between the laminar dot sign (LDS) and the deep optic nerve head (ONH) structure in eyes with primary-open-angle glaucoma (POAG). METHODS: Eighty-four eyes of 84 patients with POAG were prospectively included. All of the patients underwent stereo optic disc photography (SDP), red-free retinal nerve fibre layer (RNFL) photography, SS-OCT, and standard automated perimetry. By evaluating the SDP, patients were classified into laminar dot sign (LDS) and non-LDS groups. The deep structure of the ONH including the anterior prelaminar depth (APLD) and prelaminar tissue thickness (PTT) were quantitated using SS-OCT. Progression was assessed by structural or functional deterioration during the average 4.3 ± 1.2 years of follow-up. RESULTS: The LDS group had deeper APLD (405.47 ± 107.55 vs. 302.45 ± 149.51, P < 0.001) and thinner PTT (74.34 ± 24.46 vs. 137.29 ± 40.07, P = 0.001) relative to the non-LDS group. By multivariate analysis, thin PTT was significantly associated with the presence of LDS (odds ratio = 0.939, P < 0.001). Structural progression was detected in 45 eyes (84.9%) in the LDS group and 8 eyes (25.8%) in the non-LDS group. Functional progression was demonstrated in 29 eyes (34.5%) in the LDS group and 6 eyes (19.4%) in the non-LDS group. The eyes with LDS had a significantly higher risk of glaucoma progression (χ2 = 5.00, degree of freedom = 1, P = 0.033). CONCLUSIONS: In eyes with POAG, the presence of LDS was associated with thinner prelaminar tissue and faster disease progression.

Differentiation of Nonarteritic Anterior Ischemic Optic Neuropathy from Normal Tension Glaucoma by Comparison of the Lamina Cribrosa.

Purpose: To compare lamina cribrosa (LC) morphology between eyes with nonarteritic anterior ischemic optic neuropathy (NAION) and eyes with normal tension glaucoma (NTG) in the Korean population. Methods: This retrospective study included 48 eyes with NAION, 48 eyes with NTG, and 48 healthy control eyes matched by age, intraocular pressure, axial length, and optic disc area. Eyes with NAION and NTG were also matched by retinal nerve fiber layer (RNFL) thickness in the affected sector. Optic nerve heads were scanned using enhanced depth imaging spectral-domain optical coherence tomography. LC depth (LCD) and the LC curvature index (LCCI) were measured at seven locations spaced equidistantly across the vertical optic disc diameter. LCD and the LCCI were compared in the three groups. Results: RNFL thicknesses of the matched affected sectors did not differ between the NAION and NTG groups (P = 0.347). LCD and the LCCI were significantly larger in the NTG group than in the NAION and healthy control groups at all seven planes (P < 0.001 each), but were comparable in the NAION and healthy control groups. The LCCI was larger in the affected than in the unaffected sector of NTG eyes (P = 0.010) but did not differ in NAION eyes (P = 1.000). LCD did not differ between affected and unaffected sectors in either NAION (P = 0.600) or NTG (P = 0.098) eyes. Conclusions: LC morphology differed in eyes with NAION and NTG, despite a similar degree of RNFL damage. Evaluation of LC morphology may help to understand the distinctive pathophysiology of NAION and to differentiate NAION from NTG eyes.

Lamina Cribrosa Moves Anteriorly After Trabeculectomy in Myopic Eyes.

Purpose: The purpose of this study was to investigate changes in lamina cribrosa (LC) depth after trabeculectomy in myopic eyes using enhanced depth imaging (EDI) spectral-domain optical coherence tomography (SD-OCT). Methods: Serial horizontal B-scans of the optic nerve head of 41 myopic eyes with primary open-angle glaucoma (POAG) were obtained before and 3 months after trabeculectomy using EDI SD-OCT. LC depth, defined as the distance from the opening plane of Bruch's membrane to the level of the anterior LC surface, was measured before and 3 months after trabeculectomy at 7 locations spaced equidistantly across the vertical optic disc diameter on B-scan images. The mean of the measurements at these seven planes was defined as the average LC depth. Factors associated with changes in LC depth were identified by linear regression. Results: Intraocular pressure (IOP) decreased from 26.3 ± 9.3 millimeters of mercury (mm Hg) preoperatively to 10.6 ± 3.5 mm Hg 3 months after trabeculectomy. LC depth was significantly lower 3 months after trabeculectomy than preoperatively (P < 0.001, all planes). The magnitude of LC depth reduction was significantly associated with younger age, higher preoperative LC depth, and greater magnitude of IOP reduction (all P ≤ 0.016). Conclusions: LC depth reduction was observed after trabeculectomy in myopic eyes. The degree of LC depth reduction was not related to the degree of myopia.

Focal lamina cribrosa defects are not associated with steep lamina cribrosa curvature but with choroidal microvascular dropout.

Focal lamina cribrosa (LC) defects have been found to play an important role in the development and progression of glaucomatous optic neuropathy. However, the mechanism of generation of focal LC defects is largely unknown. This cross-sectional study was performed to investigate LC curvature and the frequency of parapapillary choroidal microvascular dropout (MvD) in glaucomatous eyes with focal LC defects. This study was conducted by a retrospective review of patients with primary open-angle glaucoma (POAG) included in an ongoing prospective study being performed at the Seoul National University Bundang Hospital (Investigating Glaucoma Progression Study). A total of 118 eyes of 118 patients with POAG, 59 with and 59 without focal LC defects, with eyes matched by age, axial length, and severity of visual field (VF) damage were included. Posterior LC bowing was assessed by calculating LC curvature index (LCCI), as the inflection of a curve representing a section of the LC, on the optic nerve head images obtained by enhanced-depth-imaging (EDI) spectral-domain optical coherence tomography (OCT). MvD was detected by OCT angiography. LCCI and MvD frequency were compared between eyes with and without focal LC defects. Mean LCCI was significantly smaller than in eyes with than without focal LC defects (9.75 ± 1.29 vs. 11.25 ± 1.39, P < 0.001). MvD was significantly more frequent in eyes with than without focal LC defects (84.7% vs. 49.2%, P < 0.001). MvD in eyes with focal LC defects showed a strong topographic correlation with the focal LC defects. These findings suggest that focal LC defects may primarily result from vascular factors rather than from mechanical strain.

Comparison of Lamina Cribrosa Morphology in Eyes with Ocular Hypertension and Normal-Tension Glaucoma.

Purpose: To characterize differences in the lamina cribrosa (LC) morphology between healthy, ocular hypertension (OHT), and naive normal-tension glaucoma (NTG) eyes. Methods: Each group consisted of 80 eyes of 80 participants who were matched for age, sex, and axial length. The participants underwent enhanced-depth-imaging volume scanning of the optic nerve head using spectral-domain optical coherence tomography. The lamina cribrosa curvature index (LCCI) and lamina cribrosa thickness (LCT) were measured in horizontal B-scan images spaced equidistantly across the vertical diameter of the optic disc. Results: The LCCIs in all seven planes were smaller in both OHT and healthy eyes than in NTG eyes (all P < 0.001), and did not differ significantly between the OHT and healthy eyes. The LCTs in all three planes were greatest in OHT eyes followed by healthy and then NTG eyes (all P < 0.001). Overall, the larger LCCI was associated with smaller LCT (P < 0.001). Conclusions: The LC was thin and steeply curved in NTG eyes than in healthy and OHT eyes. In OHT eyes, the LC was thick, and its curvature was comparable to healthy eyes. Longitudinal studies are required to examine whether the straight and thickened LCs in OHT eyes precede the onset of OHT or are a protective response to elevated intraocular pressure.

One year structural and functional glaucoma progression after trabeculectomy.

We evaluated the changes in visual field mean deviation (VF MD) and retinal nerve fibre layer (RNFL) thickness in glaucoma patients undergoing trabeculectomy. One hundred patients were examined with VF and spectral-domain optical coherence tomography (OCT) before trabeculectomy and 4 follow-up visits over one year. Linear mixed models were used to investigate factors associated with VF and RNFL. VF improved during the first 3 months of follow-up (2.55 ± 1.06 dB/year) and worsened at later visits (-1.14 ± 0.29 dB/year). RNFL thickness reduced by -4.21 ± 0.25 µm/year from 1st month of follow-up. Eyes with an absence of initial VF improvement (ß = 0.64; 0.30-0.98), RNFL thinning (ß = 0.15; 0.08-0.23), increasing intraocular pressure (IOP; ß = -0.11; -0.18 to -0.03) and severe glaucoma (ß = -10.82; -13.61 to -8.02) were associated with VF deterioration. Eyes with VF deterioration (ß = 0.19; 0.08-0.29), increasing IOP (ß = -0.09; -0.17 to -0.01), and moderate (ß = -6.33; -12.17 to -0.49) or severe glaucoma (ß = -19.58; -24.63 to -14.52) were associated with RNFL thinning. Changes in RNFL structure and function occur over a 1-year follow-up period after trabeculectomy. Early VF improvement is more likely to occur in patients with mild/moderate glaucoma, whereas those with severe glaucoma show greater decline over one year. Our findings indicate that progression is observable using OCT, even in late-stage glaucoma.

Relationship between lamina cribrosa curvature and the microvasculature in treatment-naïve eyes.

BACKGROUND/AIMS: To investigate the relationship between the lamina cribrosa (LC) curvature and the microvasculature within the LC in treatment-naïve eyes with normal-tension glaucoma (NTG) and in healthy eyes. METHODS: Forty-one eyes with treatment-naïve NTG and 41 age and sex-matched healthy control eyes were included. The optic nerve head (ONH) area was scanned using spectral-domain optical coherence tomography (OCT) to examine the LC curvature quantified as the LC curvature index (LCCI). OCT angiography of the ONH area was performed to determine the LC vessel density (LCVD) in the en face images obtained from the layer segmented at the level of the LC. The LCVD was calculated as the percentage area occupied by vessels within the measured region. RESULTS: The LCCI was larger (9.53±1.33 vs 6.55±1.02, p<0.001) and LCVD was smaller (28.0%±6.1% vs 35.2±6.3%, p<0.001) in NTG eyes than in healthy eyes. There were overall significant associations of a smaller retinal nerve fibre layer (RNFL) thickness (p<0.001), a smaller visual field mean deviation (MD) (p=0.003) and a larger LCCI (p≤0.004) with a smaller LCVD. In NTG group, the LCVD was positively associated with the RNFL thickness (p=0.012) and visual field MD (p=0.023), and negatively associated with the axial length (p≤0.013) and LCCI (p≤0.007). In healthy group, a smaller RNFL thickness (p=0.023) was associated with a smaller LCVD. CONCLUSION: A larger LCCI was significantly associated with a smaller LCVD in treatment-naïve NTG eyes but not in healthy eyes, indicating that mechanical strain potentially influences the perfusion within the LC in eyes with NTG.

Association of Corneal Hysteresis With Lamina Cribrosa Curvature in Primary Open Angle Glaucoma.

Purpose: To investigate whether corneal biomechanical properties are associated with the lamina cribrosa (LC) curvature in eyes with primary open angle glaucoma (POAG). Methods: Corneal biomechanical properties and LC curvature were assessed in 65 treatment-naïve POAG patients. Corneal biomechanical properties, including corneal hysteresis (CH), corneal resistance factor (CRF), and corneal-compensated intraocular pressure (IOPcc), were measured using an ocular response analyzer (ORA; Reichert Ophthalmic Instruments). LC curvature was assessed by measuring the LC curvature index (LCCI) on B-scan images obtained using spectral-domain optical coherence tomography (OCT). The LCCI was determined by measuring LC curve depth on the anterior LC surface and the width of the reference line. Results: The LCCI was correlated with CH (P = 0.001), CRF (P = 0.012) and IOPcc (P = 0.001) in the univariate analysis. To adjust multicollinearity, principal component analysis was performed, and multivariate regression analyses were conducted using one variable from each component. The larger LCCI was associated with larger IOPcc (P < 0.001), smaller CRF (P = 0.001) and smaller CH (P < 0.001). Conclusions: Lower CH was associated with a more posteriorly curved LC in treatment naïve POAG patients. This finding may provide a basic explanation for the reported association between CH and an increased risk for glaucoma development and progression, and support a potential value of CH for risk assessment for glaucoma.

Elucidation of the Strongest Factors Influencing Rapid Retinal Nerve Fiber Layer Thinning in Glaucoma.

Purpose: To determine which groupings of prognostic factors best explain the rapid progressive retinal nerve fiber layer (RNFL) thinning in patients with primary open-angle glaucoma (POAG). Methods: Optic nerves of 111 POAG patients who were followed for at least 2.5 years, during which the RNFL thickness was measured by serial spectral-domain optical coherence tomography (OCT) were included. Eyes were imaged using enhanced depth-imaging spectral-domain OCT and swept-source OCT angiography to determine the lamina cribrosa curvature index (LCCI), and the presence of a choroidal microvasculature dropout (cMvD), respectively. The rate of RNFL thinning was determined by linear regression of serial OCT RNFL thickness measurements. A regression tree model was used to find groupings of factors that best explain the rate of future RNFL thinning. Results: Disc hemorrhage, larger LCCI, and presence of cMvD were associated with faster global RNFL thinning in the multivariate regression analysis. The regression tree analysis revealed three stratified groups based on the rate of RNFL thinning, divided by the LCCI and the presence of cMvD. Eyes with LCCI ≥11.87 had the fastest RNFL thinning (-2.4 ± 0.8 µm/year, mean ± SD). Among eyes with LCCI <11.87, the presence of cMvD was the strongest factor influencing faster RNFL thinning (-1.5 ± 0.8 µm/year). Eyes with LCCI <11.87 and without a cMvD exhibited the slowest RNFL thinning (-0.8 ± 0.9 µm/year). Conclusions: Our regression tree model demonstrated that larger LCCI, and then the presence of cMvD were the first and second strongest prognostic factors for faster progressive RNFL thinning. Further studies may be needed to confirm these findings.

Intereye Comparison of Lamina Cribrosa Curvature in Normal Tension Glaucoma Patients With Unilateral Damage.

Purpose: To investigate intereye differences in lamina cribrosa (LC) morphology in normal tension glaucoma (NTG) patients with unilateral damage. Methods: A total of 152 eyes of 76 treatment-naive NTG patients with unilateral damage from the ongoing Investigating Glaucoma Progression Study were included. Optic nerve heads were scanned using enhanced-depth spectral-domain optical coherence tomography. The magnitude of the LC curve and LC position were assessed by measuring the LC curve index (LCCI) and LC depth (LCD), respectively, at seven locations spaced equidistantly across the vertical optic disc diameter. LCCI and LCD were compared between glaucomatous and fellow healthy eyes. Results: Eyes with NTG had larger average LCCI and LCD than contralateral healthy eyes (for both P < 0.002). The LCCI was greater in the glaucomatous eyes at all seven locations (P < 0.001). Univariate conditional logistic regression analysis showed that higher baseline intraocular pressure (P = 0.010), deeper LCD (P = 0.007), and larger LCCI (P < 0.001) were significantly associated with the presence of glaucoma. In multivariate analysis, only larger LCCI was significantly associated with the presence of glaucoma (P < 0.001). Conclusions: Glaucomatous eyes have more steeply curved LC than fellow healthy eyes. This finding suggests that LC undergoes significant remodeling in NTG eyes.

Changes in the Anterior Lamina Cribrosa Morphology with Glaucoma Severity.

This study was designed to evaluate if primary open angle glaucoma (POAG) and its severity are associated with the shape of the lamina cribrosa (LC) as measured by a global shape index (LC-GSI), or other indices of LC curvature or depth. Optical coherence tomography (OCT) scans of the optic nerve head (OHN) were obtained from subjects with POAG (n = 99) and non-glaucomatous controls (n = 76). ONH structures were delineated, the anterior LC morphology reconstructed in 3D, and the LC-GSI calculated (more negative values denote greater posterior concavity). Anterior LC depth and 2D-curvature were also measured. Severity of glaucoma was defined by the extent of visual field loss, based on the Hodapp-Parrish-Anderson grading. Linear regression analyses compared LC characteristics between controls, mild-moderate, and advanced POAG groups. After adjusting for age, gender, ethnicity, intraocular pressure, axial length and corneal curvature, the LC-GSI was most negative in the advanced POAG group (mean [standard error] = -0.34 [0.05]), followed by the mild-moderate POAG group (-0.31 [0.02]) and then controls (-0.23 [0.02], PTrend = 0.01). There was also a significant trend of increasing LC depth and greater LC horizontal curvature with increasing severity of glaucoma (PTrend = 0.04 and 0.02, respectively). Therefore, with more severe glaucoma, the LC-GSI was increasingly more negative, and the anterior LC depth and curvature greater. These observations collectively correspond to greater cupping of the ONH at the level of the LC. As the LC-GSI describes the 3D anterior LC morphology, its potential usage may be complementary to existing ONH parameters measured on OCT.

Age-Dependent Variation of Lamina Cribrosa Displacement During the Standardized Valsalva Maneuver.

Based on biomechanical theory, lamina cribrosa (LC) displacement, the key component of progressive glaucomatous change, is presumed to be dependent on intraocular pressure (IOP) as well as tissue stiffness of LC. In the performance of the Valsalva maneuver, both IOP and cerebrospinal fluid pressure can increase. The present study investigated the age-dependent variation of LC displacement during the standardized Valsalva maneuver in healthy subjects. Sixty-three (63) eyes (age range: 20-76 years) were prospectively underwent IOP measurement and Cirrus HD-OCT optic disc scans before and during the standardized Valsalva maneuver. During the standardized Valsalva maneuver, the IOP significantly increased from 13.2 ± 2.9 mmHg to 18.6 ± 5.2 mmHg (P < 0.001). The maximal LC depth significantly decreased in the younger age groups (age: 20 s to 40 s) but not in the older age groups (age: over 50). The BMO distance did not change significantly. Younger age (P = 0.009), a smaller increase of IOP during the Valsalva maneuver (P = 0.002), and greater baseline maximal LC depth (P = 0.013) were associated with more anterior displacement of the LC during the standardized Valsalva maneuver. Taken together, age as well as translaminar pressure dynamics seems to play a crucial role in LC biomechanics.

Lamina Cribrosa Curvature in Healthy Korean Eyes.

Given that posterior bowing of the lamina cribrosa (LC) is a principle event in the development of glaucomatous damage, assessment of the LC morphology may have clinical utility in diagnosing and managing glaucoma patients. LC curvature has been suggested as an index to evaluate the LC morphology. To apply LC morphology in clinical practice, it is necessary to know normal profiles of LC curvature in healthy population. This study was performed to investigate the characteristics of LC curvature in healthy eyes using enhanced depth imaging spectral-domain optical coherence tomography in a total of 250 eyes of 125 healthy Korean subjects. The lamina cribrosa curvature index (LCCI) values at seven locations spaced equidistantly across the vertical optic disc diameter were measured on serial horizontal B-scan images. The mean value of the seven measurements was defined as the average LCCI. The average LCCI was 7.46 ± 1.22 (range, 4.29-10.48) and did not differ significantly between the right and left eyes. There was a strong inter-eye correlation within subjects. LCCI was significantly larger in eyes with shorter axial length (P < 0.001). The observed range of LCCI in healthy subjects may be used as a reference for evaluating LC curvature in glaucomatous eyes.

The association between prelaminar tissue thickness and peripapillary choroidal thickness in untreated normal-tension glaucoma patients.

To evaluate the association between prelaminar tissue thickness (PLT) and peripapillary choroidal thickness (PCT) in untreated normal-tension glaucoma (NTG) patients.A cross-sectional study was conducted in 65 untreated NTG patients. All of the subjects were imaged with swept-source optical coherence tomography (SS-OCT, DRI OCT; Topcon, Tokyo, Japan) to obtain the horizontal scan crossing the optic nerve head center. The PLT was calculated by subtracting the anterior prelaminar depth (APLD) from the anterior lamina cribrosa depth (ALCD). The retinal nerve fiber layer thickness and PCT were measured automatically using the in-built automated software of the OCT device. Spearman correlation analysis was conducted to investigate the ocular factors that were associated with PLT.The average PLT, APLD, ALCD, and PCT values were 134.05 ±â€Š55.54, 314.59 ±â€Š113.59, 448.64 ±â€Š125.69, and 121.23 ±â€Š59.56 µm, respectively. PLT was correlated with the axial length, visual field index (VFI), ALCD, and PCT. When the subjects were divided into 2 groups according to their PLT values (median value, 125.114 µm), the thin PLT group showed worse mean deviation, VFI values, and thinner PCT when compared to the thick PLT group.The PLT was significantly associated with the PCT, and the thinner PLT showed the greater glaucomatous damage in untreated NTG. The thickness of the prelaminar tissue may be related with the choroidal blood flow in untreated NTG patients.

Lamina Cribrosa Morphology in Glaucomatous Eyes with Hemifield Defect in a Korean Population.

PURPOSE: To compare regional variations in lamina cribrosa (LC) curvature and depth between healthy eyes (group 1) and naïve eyes with primary open-angle glaucoma (POAG) having superior (group 2), inferior (group 3), and both (group 4) hemifield retinal nerve fiber layer (RNFL) defects. DESIGN: Cross-sectional study. PARTICIPANTS: Each group consisted of 39 eyes of 39 Korean patients who were matched for age, sex, and axial length. METHODS: The LC curvature index (LCCI) and LC depth (LCD) were measured in B-scan images obtained using enhanced depth imaging OCT at 7 locations spaced equidistantly across the vertical optic disc diameter. Superior and inferior LCCI and LCD were compared by calculating the superior-to-inferior (Sup/Inf) ratios. MAIN OUTCOME MEASURES: Comparisons of LCCI, LCD, and Sup/Inf ratio among the 4 groups. RESULTS: Compared with healthy eyes (group 1), LCCIs were larger at the superior and middle planes in group 2, at the inferior and middle planes in group 3, and at all planes in group 4 (P ≤ 0.003). The LCD showed similar results, but there was no difference in superior planes between groups 1 and 2. The Sup/Inf ratio of LCCI differed significantly between groups 1 (1.03) and 2 (1.20), groups 1 and 3 (0.79), groups 2 and 3, groups 2 and 4 (0.96), and groups 3 and 4 (all P < 0.001), but not between groups 1 and 4 (P = 0.273). The Sup/Inf ratio of LCD differed only between groups 2 and 3 (P = 0.002). CONCLUSIONS: Eyes with POAG showed regional differences in LC morphology, corresponding with the location of RNFL defects. The regional variations in LCCI suggest that LC morphology in POAG would be better assessed on a regional basis than by a global index.

Microvascular Changes in Peripapillary and Optic Nerve Head Tissues After Trabeculectomy in Primary Open-Angle Glaucoma.

Purpose: To determine microvasculature changes in the deep optic nerve head (ONH) and peripapillary tissues after trabeculectomy, and to correlate these with changes in the lamina cribrosa (LC) curvature. Methods: Fifty-six eyes with primary open-angle glaucoma that underwent trabeculectomy were included. The optic nerve and peripapillary microvasculature were evaluated in en face images obtained using optical coherence tomography (OCT) angiography (OCTA) before and 3 months after trabeculectomy. The OCTA-derived vessel density (VD) was calculated in each layer segmented into the prelaminar tissue (PLT), LC, peripapillary retina (PR), and peripapillary choroid (PPC). Swept-source OCT volume scanning of ONH was performed on the same day as OCTA to examine the change in LC curvature quantified as the LC curve index (LCCI). Results: At 3 months postoperative, the IOP and LCCI had significantly decreased (both P < 0.001). OCTA images revealed a significant increase in VD in the LC (P = 0.006), but not in the PLT, PR, or PPC. Twenty-six eyes showed both significant LCCI decrease and VD increase based on 95% Bland-Altman limits of agreement. The VD increase in the LC was significantly associated with larger percentage reductions in IOP (P = 0.040) and LCCI (P < 0.001) in the univariate analysis. Multivariate analysis revealed that only the LCCI reduction was a significant factor affecting the VD increase in the LC. Conclusions: A significant increase in VD was observed at the level of the LC after trabeculectomy. The VD increase was more strongly associated with the reduction in the LC curvature than with the reduction of IOP.

Three-Dimensional Ultrasonic Needle Tip Tracking with a Fiber-Optic Ultrasound Receiver.

Ultrasound is frequently used for guiding minimally invasive procedures, but visualizing medical devices is often challenging with this imaging modality. When visualization is lost, the medical device can cause trauma to critical tissue structures. Here, a method to track the needle tip during ultrasound image-guided procedures is presented. This method involves the use of a fiber-optic ultrasound receiver that is affixed within the cannula of a medical needle to communicate ultrasonically with the external ultrasound probe. This custom probe comprises a central transducer element array and side element arrays. In addition to conventional two-dimensional (2D) B-mode ultrasound imaging provided by the central array, three-dimensional (3D) needle tip tracking is provided by the side arrays. For B-mode ultrasound imaging, a standard transmit-receive sequence with electronic beamforming is performed. For ultrasonic tracking, Golay-coded ultrasound transmissions from the 4 side arrays are received by the hydrophone sensor, and subsequently the received signals are decoded to identify the needle tip's spatial location with respect to the ultrasound imaging probe. As a preliminary validation of this method, insertions of the needle/hydrophone pair were performed in clinically realistic contexts. This novel ultrasound imaging/tracking method is compatible with current clinical workflow, and it provides reliable device tracking during in-plane and out-of-plane needle insertions.

Peripapillary Vessel Density in Glaucomatous Eyes: Comparison Between Pseudoexfoliation Glaucoma and Primary Open-angle Glaucoma.

PURPOSE: The aim of this study was to compare the peripapillary vessel density between eyes with pseudoexfoliation glaucoma (PXG) and eyes with primary open-angle glaucoma (POAG). METHODS: Peripapillary vessel density in the radial peripapillary capillaries was assessed using optical coherence tomography angiography, and compared between patients with PXG and those with POAG, matched for age and mean deviation (MD) of standard automated perimetry. The vessel density was measured between the optic disc margin and 750 µm from the optic disc margin. RESULTS: In total, 39 eyes with PXG were matched to 39 eyes with POAG. Mean untreated intraocular pressure was higher in the PXG group than in the POAG group (21.4±6.7 vs. 14.9±2.9 mm Hg; P<0.001), but there was no difference in age, refractive error, visual field MD, or average retinal nerve fiber layer thickness between the 2 groups. However, the average peripapillary vessel density in the radial peripapillary capillaries was lower in the eyes with PXG than in the eyes with POAG. Moreover, there was a significant correlation between peripapillary vessel density and both visual field MD and retinal nerve fiber layer thickness. CONCLUSIONS: Peripapillary vessel density was lower in eyes with PXG than in eyes with POAG of similar severity.