Comparison of the lamina cribrosa parameters in eyes with exfoliation syndrome, exfoliation glaucoma and healthy subjects

Comparative Analysis of Lamina Parameters in Nonglaucomatous Eyes With and Without Pseudoexfoliation Syndrome

OBJECTIVE

To compare lamina cribrosa (LC) parameters in nonglaucomatous eyes with pseudoexfoliation syndrome (PXFS) and healthy control eyes to assess structural alterations that may contribute to early glaucoma pathophysiology.

DESIGN

Retrospective, cross-sectional study.

PARTICIPANTS

Fifty eyes with non-glaucomatous PXFS and 50 healthy, age-matched control eyes.

METHODS

All participants underwent spectral-domain optical coherence tomography with enhanced-depth imaging. LC parameters were measured at the superior mid-peripheral, central, and inferior mid-peripheral regions. Comparisons between groups were assessed with paired t-tests for continuous data and the McNemar test for categorical data. Mixed effects model analysis was utilized to identify factors associated with lamina cribrosa thickness (LCT).

MAIN OUTCOME MEASURES

Measurements of LCT, lamina cribrosa curvature depth (LCCD), curvature index (LCCI), and prelaminar tissue thickness (PLTT).

RESULTS

Eyes with PXFS exhibited significantly thinner LCT than controls across all regions: superior mid-peripheral (163.85 ± 39.13 µm vs. 222.18 ± 38.03 µm), central (172.95 ± 40.63 µm vs. 220.17 ± 51.77 µm), and inferior mid-peripheral (165.58 ± 35.18 µm vs. 217.73 ± 44.00 µm). No significant differences were observed in PLTT, LCCD and LCCI between the 2 groups. Multivariable mixed effects model analysis identified the presence of PXFS (β = -50.687) as an independent factor associated with LCT.

CONCLUSION

PXFS eyes show significant LC thinning, potentially representing early structural changes preceding glaucoma. Monitoring LC parameters in PXFS eyes may facilitate early detection of patients at risk of disease progression.

Evaluation of the lamina cribrosa after topical latanoprost therapy in primary open-angle glaucoma or ocular hypertension

PURPOSE

To investigate that the changes of lamina cribrosa (LC) thickness and depth after latanoprost therapy in primary open-angle glaucoma (POAG) and ocular hypertension (OHT) patients.

METHODS

In this single-center prospective cross-sectional study, 35 eyes from 35 patients with POAG or OHT (study group) and 26 age- and gender- matched healthy individuals (control group) were included. All participants were examined by spectral domain optical coherence tomography (SD-OCT) with enhanced depth imaging (EDI) mode for LC thickness and depth measurements at the first visit before latanoprost therapy and at visits after 1 (second visit) and 3 (third visit) months of latanoprost therapy.

RESULTS

The mean LC thickness in both horizontal and vertical scans of the study group were thinner than the control group (p < 0.001, for both). During latanoprost therapy in the study group, the LC thickness values in horizontal scans significantly differed over the three visits, gradually increased (p < 0.05). There was significantly decrease in LC depth in horizontal scans between the first and third visits, and the second and third visits (p = 0.003 and p = 0.008, respectively). The gradual decrease in LC depth in vertical scans was observed at all visits, but the statistically significant difference was between the first and third visits only (p = 0.048).

CONCLUSION

POAG/OHT patients showed more LC thinning compared with healthy individuals. The significant increase in LC thickness and the significant decrease in LC depth were detected after IOP reduction therapy with latanoprost in ocular hypertensive/ glaucomatous eyes.

Is Keratoconus More Than Just a Corneal Disease?

PURPOSE

The aims of this study were to compare the scleral thickness (ST), lamina cribrosa thickness (LCT), and lamina cribrosa curvature index between patients with keratoconus and healthy controls and to evaluate the relationship between these values and corneal parameters.

METHODS

This cross-sectional study included 41 eyes of 41 patients with keratoconus and 30 eyes of 30 age-matched, sex-matched, and axial length-matched controls. Nasal and temporal STs were measured vertically, 4 mm posterior to the scleral spur, using anterior segment optical coherence tomography. The LCT was measured on the radial scans of the optic nerve head. The lamina cribrosa curvature index (lamina cribrosa curvature depth/curvature width × 100) was calculated to determine the degree of posterior bowing of the lamina cribrosa.

RESULTS

The nasal ST and temporal ST were significantly lower in the keratoconus group than in the control group ( P = 0.016 and P = 0.023, respectively). The LCT was significantly lower in the keratoconus group compared with the control group ( P < 0.001). There was no significant difference between the groups for the lamina cribrosa curvature index ( P = 0.375). Correlation analysis revealed a significant correlation between the nasal and temporal STs and the central corneal thickness (r = 0.376, P < 0.001 and r = 0.387, P < 0.001, respectively). There was also a significant correlation between the temporal ST and the minimum corneal thickness in the keratoconus group (r = 0.332, P = 0.015). The LCT was significantly correlated with the central corneal thickness (r = 0.445, P < 0.001).

CONCLUSIONS

Structural features of the cornea, sclera, and lamina cribrosa with similar collagen content may be similarly affected in patients with keratoconus. Further histologic studies are needed to confirm our results.

Diagnostic Performance of Optical Coherence Tomography for Pseudoexfoliation Glaucoma

PRECIS

LC thickness and LCCI had comparable diagnostic performances with RNFL thickness in distinguishing eyes with PXG from those with PXS. BMO-MRW showed the lowest diagnostic performance among all geometric parameters derived from OCT scans we evaluated.

OBJECTIVE

To compare the diagnostic performance of different geometric parameters derived from optical coherence tomography (OCT) scans (retinal nerve fiber layer [RNFL] thickness, lamina cribrosa [LC] thickness, LC curvature index [LCCI] and Bruch's membrane opening-minimum rim width [BMO-MRW]) for distinguishing eyes with pseudoexfoliation glaucoma (PXG) from pseudoexfoliation syndrome (PXS) and healthy eyes.

METHODS

Fifty-five eyes of 55 patients with PXG, 55 eyes of 55 patients with PXS, and 50 healthy subjects were enrolled in this cross-sectional study. The areas under the receiver operating characteristic curves (AUCs) of RNFL thickness, LC thickness, LCCI and BMO-MRW were calculated and compared.

RESULTS

In discriminating between eyes with PXG from those with PXS, LC thickness (0.930 [95% CI: 0.883-0.978]) and global RNFL thickness (0.974 [95% CI: 0.947-0.992]) presented comparable AUCs (P=0.244). In distinguishing subjects wiht PXG from healthy controls, both LC thickness (0.972 [95% CI: 0.948-0.997]) and LCCI (0.983 [95% CI: 0.968-0.998]) had comparable AUCs with global RNFL thickness (0.988 [95% CI: 0.974-1.000]) (P=0.094 andP=0.239, respectively). Global BMO-MRW had lower AUCs than RNFL thickness (0.839 [95% CI: 0.759-0.920] and 0.897 [95% CI: 0.836-0.958], respectively) in distinguishing PXG from both PXS and healthy controls (P=0.001 andP=0.002, respectively). BMO-MRW also had significantly lower AUCs than both LC thickness and LCCI in distinguishing PXG from healthy controls (P=0.034 andP=0.001, respectively).

CONCLUSION

LC thickness and LCCI had better diagnostic performance than BMO-MRW in distinguishing PXG from PXS and healthy controls, which were comparable to RNFL thickness.

Effect of pseudoexfoliation syndrome on lamina cribrosa morphology after uneventful phacoemulsification

AIM

To evaluate the behavior of the lamina cribrosa (LC) following successful phacoemulsification (PE) surgery in non-glaucomatous PXS cases with cataract.

METHODS

A total of 25 bilateral PXS and 56 non-PXS cataract patients were included in this prospective, interventional, and controlled study. The lamina cribrosa thickness (LCt) and anterior laminar depth (ALD) were measured horizontally and vertically from two sections using EDI-OCT. The measurements were taken preoperatively, and the LCt and ALD measurements were repeated at week one (W1), month one (M1), month two (M2), and month three (M3) postoperatively.

RESULTS

The baseline horizontal and vertical LCt values were found to be significantly thinner in the PXS group (p = 0.001, p = 0.006 respectively). The horizontal section ALD values were 463.32 ± 98.82 µm and 383.88 ± 85.8 µm (p < 0.001) for the PXS and non-PXS groups, respectively, and this significance continued during follow-up. The vertical ALD values were 469.64 ± 117.83 µm and 390.3 ± 98.1 µm (p = 0.002) in the PXS and non-PXS groups, respectively. There was no significant change in the PXS group for the depth following PE, but a statistically significant depth increase response was observed in the non-PXS group during follow-up.

CONCLUSION

It is possible to conclude that the bending capacity of the lamina cribrosa may be lower than seen in the normal population, but we do not know how this lack of flexibility will affect the eye.

Modeling of the increased intraocular pressure effect on changes in the stress state of the eyeball’s internal structures

The aim of the study was creating a model and evaluating the effect of elevated IOP in the anterior chamber during phacoemulsification on the changes in the stress state of various ocular structures. Materials and methods.A simplified axial symmetrical anatomical model of the eyeball was created using the finite element method. Using the Deform software package, the deformation problem was worked out by calculating the redistribution of the excess pressure in the anterior chamber during phacoemulsification, on the changes in the stress state of different ocular structures.Results. At processing of modeling results, data were obtained on redistribution of the excess pressure delivered to the anterior chamber towards its decrease in the posterior pole area. The pressure level amounted to 0.85 % of excess pressure applied. The findings are supported by few animal experiments. Conclusions.Proposed model of the increased IOP level effect on changes in the stressed state of various ocular structures demonstrates that the autoregulation mechanism maintaining ocular blood flow at a constant level includes a compensating mechanism for a steep IOP increase due to elastic properties of the vitreous body. This model allows calculating the redistribution of pressure in different parts of the eyeball, depending on the state of resilient-elastic properties of the vitreous, as well as on avitreal eyes, and in patients with silicone oil tamponade.