Relationship between Corneal Biomechanical Properties and Optic Nerve Head Changes after Deep Sclerectomy

Comparison of Goldmann and ORA tonometers in newly diagnosed, untreated, POAG and OHT eyes

BACKGROUND AND OBJECTIVE

The corneal biomechanical properties in naïve, untreated glaucoma and ocular hypertension (OHT) eyes is interesting, because it may be a source of error in intraocular pressure (IOP) measurements by Goldmann applanation tonometer (GAT) and Ocular Response Analyzer (ORA) The main objective of this study was to evaluate the IOP values obtained using GAT and the ORA, in primary open angle glaucoma (POAG) and in OHT untreated eyes.

MATERIAL AND METHODS

Observational, masked, cross sectional observational study. Newly diagnosed, untreated POAG and OHT eyes were included.

RESULTS

51 POAG and 34 OHT eyes were analyzed. We found that IOPcc (IOP corneal-compensated) was significantly higher than GAT IOP in POAG (p = 0.0002) while we did not find any significant difference between both tonometers in OHT (p = 0.1).

CONCLUSIONS

GAT seems to underestimate the real IOP in untreated POAG eyes and it seems to be quite accurate in OHT eyes.

Modification of Corneal Biomechanics and Intraocular Pressure Following Non-Penetrating Deep Sclerectomy

Changes in the cornea can influence outcomes in patients with primary open-angle glaucoma (POAG). We aimed to evaluate the relevance of changes in corneal biomechanics and intraocular pressure (IOP) in patients undergoing non-penetrating deep sclerectomy (NPDS) with the Esnoper V2000 implant^® (AJL Ophthalmic S.A., Gasteiz, Spain). We included 42 eyes of 42 patients with POAG scheduled for NPDS with the Esnoper V2000 implant. Biomechanical properties were measured by Ocular Response Analyzer^® G3 (ORA; Reichert Inc., Depew, NY, USA). Corneal hysteresis (CH), corneal resistance factor (CRF), corneal compensated IOP (IOPcc), and Goldmann-correlated IOP (IOPg) were measured the day before surgery and on day 1, 7, and 30 and 2 and 3 months after surgery. CH initially increased, fell below the presurgical value at 30 days after the surgery, and increased again at 2 and 3 months. CRF, IOPcc, and IOPg decreased on the first day after surgery, then followed a trend of increasing but stayed below pre-surgery levels. All values reached statistical significance. While observed changes in corneal biomechanics after NPDS and Esnoper V2000 implant were significant, more studies are needed if we are to understand their influence on corneal biomechanics and their clinical relevance in POAG.

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.

Corneal Biomechanical Changes Caused by Acute Elevation of IOP in Eyes with and without Glaucoma

SIGNIFICANCE

Although corneal biomechanical parameters are well linked with glaucoma, their clinical utility has not yet been fully elucidated. This study was designed to provide unique evidence about the dynamic nature of corneal biomechanical parameters and their potential prognostic ability for glaucoma.

PURPOSE

This study aimed to evaluate the effect of acute intraocular pressure (IOP) elevation on corneal hysteresis (CH) and corneal resistance factor (CRF) and the associations of these biomechanical parameters with glaucomatous disease.

METHODS

Subjects participating in a prospective, longitudinal glaucoma research study had CH and CRF measured before and during ophthalmodynamometry during visits in the years 2011 to 2012. All participants were diagnosed with primary open-angle glaucoma, ocular hypertension, glaucoma suspect, or normal eyes and had a minimum of 3 years of study participation with at least five reliable visual field (VF) tests. Changes in CH, CRF, and IOP induced by ophthalmodynamometry were compared between diagnostic groups and evaluated for relationships with existing and future glaucomatous VF loss.

RESULTS

In 248 eyes of 248 subjects followed up for 7.7 ± 2.3 years, ophthalmodynamometry induced a mean IOP increase from 15.1 to 29.9 mmHg, causing a mean 34 ± 28% increase in CRF and 21 ± 25% decrease in CH. Magnitude of CH change did not differ between diagnostic groups or between eyes that did (n = 20) and did not (n = 95) develop new VF loss during the study period, nor was it related to rate of future VF progression.

CONCLUSIONS

Ophthalmodynamometry-induced IOP elevation resulted in significant acute changes in CH and CRF in this study; this suggests accounting for IOP may be important in clinical interpretation of these parameters. However, because the degree of CH change was not related to glaucoma or its progression, acute changes in CH and CRF do not seem to have a prognostic value for glaucoma.

Bilateral decompression retinopathy after deep sclerectomy with mitomycin C in a child with tubulointerstitial nephritis and uveitis syndrome

INTRODUCTION

To report the first case of bilateral ocular decompression retinopathy after uneventful non-perforating deep sclerectomy with mitomycin C in a child with tubulointerstitial nephritis and uveitis syndrome.

CASE DESCRIPTION

An 8-year-old girl affected by tubulointerstitial nephritis and uveitis syndrome developed ocular hypertension (45 mmHg in the right eye and 42 mmHg in the left eye) associated with recurrent episodes of uveitis and chronic use of steroids despite maximum hypotensive medical treatment. Bilateral non-perforating deep sclerectomy with mitomycin C (0.2 mg/mL, 1 min) was performed under general anesthesia without complications. The first postoperative day, the visual acuity was reduced to 0.6 in the right eye and 0.05 in the left eye and the intraocular pressure was 3 mmHg in both eyes. Fundoscopy revealed bilateral optic nerve swelling and diffuse retinal hemorrhages, some of them with scattered-white centers. About 2 months after surgery, the visual acuity was normal and the fundus examination showed complete resolution.

CONCLUSION

The ocular decompression retinopathy is an uncommon complication after non-perforating deep sclerectomy. This is the first case of bilateral ocular decompression retinopathy reported after non-perforating deep sclerectomy in a child with ocular hypertension secondary to recurrent uveitis and chronic use of steroids associated with tubulointerstitial nephritis and uveitis syndrome.

Factors associated with lamina cribrosa displacement after trabeculectomy measured by optical coherence tomography in advanced primary open-angle glaucoma

PURPOSE

To investigate the relationship of lamina cribrosa displacement to corneal biomechanical properties and visual function after mitomycin C-augmented trabeculectomy.

METHOD

Eighty-one primary open-angle eyes were imaged before and after trabeculectomy using an enhanced depth spectral domain optical coherence tomography (SDOCT). Corneal biomechanical properties were measured with the ocular response analyzer before the surgery. The anterior lamina cribrosa (LC) was marked at several points in each of the six radial scans to evaluate LC displacement in response to intraocular pressure (IOP) reduction. A Humphrey visual field test (HVF) was performed before the surgery as well as 3 and 6 months, postoperatively.

RESULTS

Factors associated with a deeper baseline anterior lamina cribrosa depth (ALD) were cup-disc ratio (P = 0.04), baseline IOP (P = 0.01), corneal hysteresis (P = 0.001), and corneal resistance factor (P = 0.001). After the surgery, the position of LC became more anterior (negative), posterior (positive), or remained unchanged. The mean LC displacement was - 42 μm (P = 0.001) and was positively correlated with the magnitude of IOP reduction (regression coefficient = 0.251, P = 0.02) and negatively correlated with age (regression coefficient = - 0.224, P = 0.04) as well as baseline cup-disk ratio (Regression coefficient = - 0.212, P = 0.05). Eyes with a larger negative LC displacement were more likely to experience an HVF improvement of more than a 3 dB gain in mean deviation (P = 0.002).

CONCLUSION

A larger IOP reduction and younger age was correlated with a larger negative LC displacement and improving HVF. The correlation between lower SDOCT cup-disc ratio and postoperative negative LC displacement was borderline (P = 0.05). Corneal biomechanics did not predict LC displacement.

Simultaneous evaluation of the lamina cribosa position and choroidal thickness changes following deep sclerectomy

PURPOSE:

To assess the changes in peripapillary and macular choroidal thickness, and in the lamina cribrosa position following deep sclerectomy.

METHODS:

Prospective study, including 39 eyes with open-angle glaucoma following deep sclerectomy. Choroidal thickness was automatically measured using swept-source optical coherence tomography at four peripapillary locations (superior, temporal, inferior, and nasal) and at the macular area in nine fields plotted with Early Treatment Diabetic Retinopathy Study grid. Optic nerve head was evaluated by Spectralis optical coherence tomography with enhanced depth imaging technology. All measurements were performed preoperatively and at 1 week and 2 months after surgery.

RESULTS:

The mean intraocular pressure significantly decreased 1 week and 2 months after surgery ( p < 0.001). A significant peripapillary choroidal thickening was observed at all locations 1 week postoperatively ( p ≤ 0.002) and in the temporal quadrant 2 months after surgery ( p = 0.027). There was a significant thickening in all macular choroidal thickness measurements at 1 week ( p < 0.001) and 2 months ( p < 0.05), except at subfoveal and inner nasal locations. The mean peripapillary and macular choroid thickness was 22.8% and 19.7% at 1 week and 6.2% and 7.8% at 2 months, respectively. A significant forward lamina cribrosa displacement occurred at every postoperative stage ( p < 0.001). Multivariate analysis showed a significant correlation between the magnitude of intraocular pressure reduction and the anterior lamina cribrosa movement (0.623, p = 0.000) and a negative correlation between the intraocular pressure change and the mean peripapillary and macular choroidal thickening (-0.527, p = 0.002; -0.568, p = 0.002, respectively).

CONCLUSION:

There was a significant reversal lamina cribrosa displacement measured from Bruch's membrane opening reference despite a significant peripapillary choroidal thickening following deep sclerectomy. Both findings were significantly correlated with the change in intraocular pressure.