The Effect of Change in Intraocular Pressure on Choroidal Structure in Glaucomatous Eyes

Three-dimensional choroidal vascularity index and choroidal thickness in fellow eyes of acute and chronic primary angle-closure using swept-source optical coherence tomography

AIM

To compare the three-dimensional choroidal vascularity index (CVI) and choroidal thickness between fellow eyes of acute primary angle-closure (F-APAC) and chronic primary angle-closure glaucoma (F-CPACG) and the eyes of normal controls.

METHODS

This study included 37 patients with unilateral APAC, 37 with asymmetric CPACG without prior treatment, and 36 healthy participants. Using swept-source optical coherence tomography (SS-OCT), the macular and peripapillary choroidal thickness and three-dimensional CVI were measured and compared globally and sectorally. Pearson's correlation analysis and multivariate regression models were used to evaluate choroidal thickness or CVI with related factors.

RESULTS

The mean subfoveal CVIs were 0.35±0.10, 0.33±0.09, and 0.29±0.04, and the mean subfoveal choroidal thickness were 315.62±52.92, 306.22±59.29, and 262.69±45.55 µm in the F-APAC, F-CPACG, and normal groups, respectively. All macular sectors showed significantly higher CVIs and choroidal thickness in the F-APAC and F-CPACG eyes than in the normal eyes (P<0.05), while there were no significant differences between the F-APAC and F-CPACG eyes. In the peripapillary region, the mean overall CVIs were 0.21±0.08, 0.20±0.08, and 0.19±0.05, and the mean overall choroidal thickness were 180.45±54.18, 174.82±50.67, and 176.18±37.94 µm in the F-APAC, F-CPACG, and normal groups, respectively. There were no significant differences between any of the two groups in all peripapillary sectors. Younger age, shorter axial length, and the F-APAC or F-CPACG diagnosis were significantly associated with higher subfoveal CVI and thicker subfoveal choroidal thickness (P<0.05).

CONCLUSION

The fellow eyes of unilateral APAC or asymmetric CPACG have higher macular CVI and choroidal thickness than those of the normal controls. Neither CVI nor choroidal thickness can distinguish between eyes predisposed to APAC or CPACG. A thicker choroid with a higher vascular volume may play a role in the pathogenesis of primary angle-closure glaucoma.

Pressure-Dependent Elevation of Vasoactive Intestinal Peptide Level in Chicken Choroid

PURPOSE

Autonomic control is important in maintaining ocular integrity. As recent data suggested that intrinsic choroidal neurons (ICN), an intrinsic choroidal autonomic control, may regulate choroidal thickening via release of the vasodilative vasoactive intestinal peptide (VIP), it was the aim of the study to investigate the level of choroidal VIP (VIP_chor) in the presence of an increased atmospheric pressure in a chicken model.

METHODS

Chicken choroidal whole mounts were exposed to ambient pressure (n = 20) and 40 mm Hg (n = 20) in a PC-controlled, open chamber system for 24 and 72 h, respectively. The VIP concentration was analyzed by ELISA, and the total protein concentration was measured by the BCA assay. Statistical analysis was done using an unpaired two-tailed t-test.

RESULTS

The pressurization systems enabled choroidal whole mount pressurization (40 mm Hg) with humidifying, pressure, temperature, and gas exchange. Overall, the VIP_chor level concentration was significantly increased at 40 mmHg compared to the ambient pressure (30.09 ± 7.18 pg vs. 20.69 ± 3.24 pg; p < 0.0001). Subgroup analysis yielded a significantly increased VIP_chor level at 40 mmHg compared to the ambient pressure after 24 h (28.42 ± 6.03 pg vs. 20.76 ± 4.06 pg; p = 0.005) and 72 h (31.77 ± 7.82 pg vs. 20.61 ± 2.12 pg; p = 0.002), respectively. The VIP_chor elevation at 40 mm Hg ranged between 1.37- (24 h) and 1.54-fold (72 h) compared to the ambient pressure. No difference was observed between the VIP_chor level at 24 h and 72 h (p > 0.05).

CONCLUSIONS

The increase of the total choroidal VIP level, representing the intracellular VIP content, in the presence of an increased ambient pressure argues for a retention of VIP within the neurons, decreasing both vasodilatation and, consequently, choroid thickness. This finding might be a passive or even active function of ICN in the regulation of choroidal thickness, ocular integrity and IOP.

The Strain Response to Intraocular Pressure Decrease in the Lamina Cribrosa of Patients with Glaucoma

OBJECTIVE

To measure biomechanical strains in the lamina cribrosa (LC) of living human eyes with intraocular pressure (IOP) lowering.

DESIGN

Cohort study.

PARTICIPANTS

Patients with glaucoma underwent imaging before and after laser suturelysis after trabeculectomy surgery (29 image pairs; 26 persons).

INTERVENTION

Noninvasive imaging of the eye.

MAIN OUTCOME MEASURES

Strains in optic nerve head tissue and changes in depths of the anterior border of the LC.

RESULTS

Intraocular pressure decreases caused the LC to expand in thickness in the anterior-posterior strain (Ezz = 0.94 ± 1.2%; P = 0.00020) and contract in radius in the radial strain (Err = - 0.19 ± 0.33%; P = 0.0043). The mean LC depth did not significantly change with IOP lowering (1.33 ± 6.26 μm; P = 0.26). A larger IOP decrease produced a larger, more tensile Ezz (P < 0.0001), greater maximum principal strain (Emax; P < 0.0001), and greater maximum shear strain (Γmax; P < 0.0001). The average LC depth change was associated with the Γmax and radial-circumferential shear strain (Erθ; P < 0.02) but was not significantly related to tensile or compressive strains. An analysis by clock hour showed that in temporal clock hours 3 to 6, a more anterior LC movement was associated with a more positive Emax, and in clock hours 3, 5, and 6, it was associated with a more positive Γmax. At 10 o'clock, a more posterior LC movement was related to a more positive Emax (P < 0.004). Greater compliance (strain/ΔIOP) of Emax (P = 0.044), Γmax (P = 0.052), and Erθ (P = 0.018) was associated with a thinner retinal nerve fiber layer. Greater compliance of Emax (P = 0.041), Γmax (P = 0.021), Erθ (P = 0.024), and in-plane shear strain (Erz; P = 0.0069) was associated with more negative mean deviations. Greater compliance of Γmax (P = 0.055), Erθ (P = 0.040), and Erz (P = 0.015) was associated with lower visual field indices.

CONCLUSIONS

With IOP lowering, the LC moves either into or out of the eye but, on average, expands in thickness and contracts in radius. Shear strains are nearly as substantial as in-plane strains. Biomechanical strains are more compliant in eyes with greater glaucoma damage. This work was registered at ClinicalTrials.gov as NCT03267849.

The impact of obesity on ocular hemodynamics and choroidal thickness

Background

Obesity affects microvascular structures. The effect of obesity on the ocular vascular system can be evaluated by changes in the choroidal thickness (CT) and retrobulbar blood flow (RBF).

Objectives

To evaluate the CT and RBF parameters in obese patients with various body mass index (BMI) values and compare these parameters with normal weight, healthy subjects.

Design

A prospective study.

Methods

The study included 102 eyes of 102 female patients. Patients were divided into three groups according to BMI as group 1 with a BMI of 18.5-24.99 (n = 32), normal weight group; group 2 with a BMI of 30-34.99 (n = 35), as obese class I; and group 3 with a BMI of 35-39.99 (n = 35), as obese class II. The peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index, and pulsatility index values of the central retinal artery (CRA) and ophthalmic artery (OA) were evaluated with color Doppler ultrasonography. CT was measured at the subfoveal area and at 500-µm intervals nasal and temporal to the fovea up to a distance of 1500 µm by using the enhanced depth imaging technique of optical coherence tomography. Intraocular pressure (IOP) was measured with a Goldmann applanation tonometry.

Results

There was a significant difference in IOP values within the groups with the highest values in group 3 (17.6 ± 2.1 mmHg) and the lowest in group 1 (12.4 ± 1.7 mmHg). The CT in groups 2 and 3 was found to be statistically significantly lower than that in group 1 at all measurement points (p < 0.001). There was a statistically significant negative correlation between CT at all measurement points and BMI (p < 0.001). The mean CRA PSV, EDV, and OA EDV values were statistically significantly lower in each obese group than those values in group 1 (p < 0.001). The OA PSV values were significantly lower in group 3 (36.5 ± 5.9 cm/s) than those in group 2 (43.8 ± 4 cm/s) and group 1 (44.6 ± 5.2 cm/s) (p < 0.001). Also, significant associations were found between BMI and CRA PSV, CRA EDV, and OA PSV values (p < 0.001).

Conclusion

Obesity may predispose to eye pathologies by changing the ocular vascular circulation.

Early evaluation of optic nerve head morphology and choroidal thickness after PreserFlo MicroShunt implantation

PURPOSE

The aim of this study is to investigate changes in choroidal and optic nerve morphological parameters following MicroShunt PreserFlo implantation. The secondary aim is to investigate how the structural changes relate to the decrease in intraocular pressure (IOP).

METHODS

Prospective observational study on 15 eyes with glaucoma requiring MicroShunt implantation. Optical coherence tomography was used to measure macular choroidal thickness (MCT), peripapillary choroidal thickness (PCT), lamina cribrosa depth (LCD), cup depth and prelaminar tissue thickness (PLT), before and one day after surgery. Results were expressed in median and interquartile range (IQR) and correlated with IOP results.

RESULTS

The IOP decreased from a median of 25 (IQR = 11) mmHg to 8 (IQR = 2) mmHg the day after surgery. Median MCT increased after MicroShunt implantation from 252.1 (IQR = 156.4) µm to a postoperative value of 318.1 (IQR = 166.6) µm (p < 0.001), with a median increase of + 87.7 µm (+ 26.4%). PCT increased from 157.2 (IQR = 109.1) µm before surgery to 206.0 (IQR = 136.1) µm after surgery (p < 0.001). Moreover, we found a significant post-operative decrease in cup depth (median reduction of - 29.3 µm, p < 0.001) and an increase in PLT (median increase of 27.3 µm, p = 0.028). On the other side, LCD reduction 24 h after surgery didn't reach any statistical significance.

CONCLUSION

PreserFlo implantation determines retinal structural changes which appear similar to those caused by traditional filtering surgery, confirming the effectiveness of this device, meantime carrying a much smaller complications rate when compared to trabeculectomy.

Choroidal Thickness in Multiple Sclerosis: An Optical Coherence Tomography Study

Background and Purpose

To identify changes in the choroidal thickness (CT) in multiple sclerosis (MS) patients with and without optic neuritis (ON) using enhanced-depth-imaging optical coherence tomography (EDI-OCT).

Methods

This cross-sectional study included 96 eyes with MS and 28 eyes of healthy controls. All participants underwent an ophthalmologic examination and EDI-OCT scanning (Spectralis, Heidelberg Engineering, Germany) to assess the CT and the retinal nerve fiber layer (RNFL) thickness. MS patients were divided into two groups: 1) with and 2) without a history of ON. The CT was evaluated in the fovea and at six horizontal and six vertical points at 500, 1,000, and 1,500 µm from the fovea. Paired t-tests were used to compare the groups, and p-value<0.05 was considered as significant.

Results

At all 13 measurements points, the CT was thicker in MS patients than in the healthy controls and was thinner in eyes with ON than in the contralateral eyes, but these differences were not statistically significant. However, the CT was always larger in all points in eyes with a history of ON than in the control eyes. The RNFL was significantly thinner (p<0.05) in both MS and ON eyes than in the control eyes.

Conclusions

The CT did not differ between MS and control eyes, but it was significantly larger in patients with a history of ON, in whom the RNFL was thinner. Further studies are necessary to establish the possible role of the choroid in MS.

Effect of SCUBA Diving on Ophthalmic Parameters

Background and Objective: Several cases of central serous chorioretinopathy (CSC) in divers have been reported in our medical retina center over the past few years. This study was designed to evaluate possible changes induced by SCUBA diving in ophthalmic parameters and especially subfoveal choroidal thickness (SFCT), since the choroid seems to play a crucial role in physiopathology of CSC. Materials and Methods: Intraocular pressure (IOP), SFCT, pachymetry, flow-mediated dilation (FMD), blood pressure, and heart rate were measured in 15 healthy volunteer divers before diving, 30 and 60 min after a standard deep dive of 25 m depth for 25 min in a dedicated diving pool (NEMO 33). Results: SFCT reduces significantly to 96.63 ± 13.89% of pre-dive values (p = 0.016) 30 min after diving. It recovers after 60 min reaching control values. IOP decreases to 88.05 ± 10.04% of pre-dive value at 30 min, then increases to 91.42 ± 10.35% of its pre-dive value (both p < 0.0001). Pachymetry shows a slight variation, but is significantly increased to 101.63 ± 1.01% (p = 0.0159) of the pre-dive value, and returns to control level after 60 min. FMD pre-dive was 107 ± 6.7% (p < 0.0001), but post-dive showed a diminished increase to 103 ± 6.5% (p = 0.0132). The pre-post difference was significant (p = 0.03). Conclusion: Endothelial dysfunction leading to arterial stiffness after diving may explain the reduced SFCT observed, but SCUBA diving seems to have miscellaneous consequences on eye parameters. Despite this clear influence on SFCT, no clear relationship between CSC and SCUBA diving can be drawn.

Choroidal Thickness and Primary Open-Angle Glaucoma-A Narrative Review

The choroid provides the majority of blood flow to the ocular tissues and structures that facilitate the processes of retinal metabolism responsible for vision. Specifically, the choriocapillaris provides a structural network of small blood vessels that supplies the retinal ganglion cells and deep ocular tissues. Similar to retinal nerve fiber layer thickness, choroidal thickness (CT) has been suggested to represent a quantifiable health biomarker for choroidal tissues. Glaucoma is a disease with vascular contributions in its onset and progression. Despite its importance in maintaining ocular structure and vascular functionality, clinical assessments of choroidal tissues have been historically challenged by the inaccessibility of CT biomarker targets. The development of optical coherence tomography angiography and enhanced depth imaging created a framework for assessing CT and investigating its relationship to glaucomatous optic neuropathy onset and progression. Pilot studies on CT in glaucoma are conflicting-with those both in support of, and against, its clinical utility. Complicating the data are highly customized analysis methods, small sample sizes, heterogeneous patient groups, and a lack of properly designed controlled studies with CT as a primary outcome. Herein, we review the available data on CT and critically discuss its potential relevance and limitations in glaucoma disease management.

[Calculation of intraocular lens power after trabeculectomy]

PURPOSE

To assess biometric changes in eyes after trabeculectomy (TE) and its impact on refractive outcomes of phacoemulsification (PE) in order to determine the corrections for calculation of intraocular lens (IOL) power.

MATERIAL AND METHODS

The study included two groups of patients: the 1^st group consisted of 116 patients who were assessed by optical biometry (IOL-Master 500) for mean biometric values before and after TE; the 2^nd group included 31 patients with history of TE (study subgroup) and 47 individuals without glaucoma (control subgroup) who underwent PE with subsequent comparison of IOL calculation accuracy.

RESULTS

There was significant axial length (AL) shortening in the 1^st group from 23.28±0.97 to 23.19±0.97 mm (p<0.001) 6 months after TE, which positively correlated (r=0.296, p=0.001) with intraocular pressure (IOP) decrease (from 25.4±5.34 to 17.2±4.42 mm Hg, p<0.001). Mean keratometry and anterior chamber depth values did not significantly change after TE. Mean IOL power calculation error after PE in the 2^nd group was -0.05±0.47 D and 0.003±0.62 D for the control and study subgroups, respectively (p=0.697). However, significant impact of preoperative IOP on IOL power calculation error was discovered in the study subgroup (R²=0.526, p<0.001), but not in the control subgroup (R²=0.061, p=0.052). Based on linear regression, the expected IOL power calculation errors depending on the preoperative IOP were determined for patients with history of TE.

CONCLUSION

AL shortening due to decrease in IOP in patients with history of TE leads to IOL power calculation errors. Expected IOL calculation error related to preoperative IOP level was determined, which could help improve refractive outcomes of PE in patients with history of TE.

Associations Between the Choroidal Vascularity Index and Malignant Glaucoma After Trabeculectomy for Primary Angle Closure Glaucoma

Purpose: To compare the choroidal vasculature characteristics by using the choroidal vascularity index (CVI) in eyes with malignant glaucoma (MG), fellow eyes with non-MG, and eyes with uncomplicated primary angle-closure glaucoma (PACG) after trabeculectomy by spectral-domain optical coherence tomography (SD-OCT). Methods: This case-control study included 53 patients diagnosed with MG after trabeculectomy. Eyes with MG (n = 53) and the fellow eyes with non-MG (n = 50) were included. Eyes with PACG without MG after trabeculectomy (n = 60) were also enrolled as controls. The choroidal parameters, including CVI and the subfoveal choroidal thickness (SFCT), were measured by using SD-OCT images. Results: Eyes with MG and the fellow eyes showed a significantly lower CVI than eyes with PACG controls (p < 0.001). After adjusting for age, sex, axial length (AL), and intraocular pressure (IOP), eyes with the greater CVI [odds ratio (OR), 0.44] were significantly related to MG. The area under the receiver operating characteristic curve of the CVI was greater than that of the SFCT in the diagnosis of MG (0.911 vs. 0.840, p = 0.034). Conclusion: Eyes with MG showed a significantly lower macular CVI than eyes with PACG controls. A higher macular CVI was an associated factor of eyes with MG. The CVI serves as a more stable and sensitive indicator for MG than the SFCT in this group of patients with PACG.

Relationship Between Changes in the Choroidal Structure and Blood Flow of the Macula After Trabeculectomy

Purpose

To elucidate the relationship between changes in the choroidal structure and blood flow of the macula after trabeculectomy.

Methods

A prospective study of 30 eyes of 30 patients with glaucoma who underwent trabeculectomy. Enhanced depth imaging optical coherence tomography with choroidal image binarization and laser speckle flowgraphy of the macula were performed at baseline and 1, 3, and 6 months postoperatively. Mixed-effects models with adjustment for confounders were used to analyze longitudinal changes in the mean choroidal thickness (mCT), mean choroidal vascular thickness (mCVT), mean choroidal interstitial thickness (mCIT), and mean blur rate (MBR).

Results

The decrease in the intraocular pressure (IOP; 45%–51%) and axial length (0.5%–0.8%) and the increase in ocular perfusion pressure (OPP; 34%–38%), mCT (16%–19%), mCVT (16%–20%), mCIT (17%–20%), and MBR (22%–25%) were significant at each postoperative time point (all P < 0.001). In the multivariate analysis, the mCVT changes were positively correlated with the OPP and MBR changes (P = 0.04 and P < 0.001, respectively), whereas the mCIT changes were negatively correlated with IOP changes (P = 0.005). The MBR changes correlated significantly with changes in mCVT but not mCIT (P < 0.001 and P = 0.39, respectively).

Conclusions

Thickness changes in the intraluminal and extraluminal parts of the choroid were closely associated with changes in blood flow and IOP, respectively, although both parts thickened comparably after IOP reduction by trabeculectomy.

Translational Relevance

The choroid reacts to IOP reduction differently between the intraluminal and extraluminal areas, blood flow dependence in the vascular area, and IOP dependence in the stromal area.

Immediate Choroidal Expansion after Bleb Needling

The purpose was to report a case of immediate choroidal expansion after a needling procedure. This is a retrospective case report of an 80-year-old male with pseudoexfoliative glaucoma who underwent Xen 45 Gel stent implantation and then trabeculectomy in the right eye. During follow-up, several bleb needling procedures were required to treat bleb fibrosis. Before and after the last bleb needling, spectral-domain optical coherence tomography (SD-OCT) was performed to investigate choroidal changes. SD-OCT was also repeated 1 week later. SD-OCT showed instant choroidal expansion (both in the macular and peripapillary area) that was quite sustained throughout the 1 week-follow-up and after 5 months. Bleb needling can cause immediate choroidal expansion that can be quite sustained throughout several months of follow-up. SD-OCT is essential for detecting choroidal changes.

Evaluating Retinal and Choroidal Perfusion Changes After Ocular Massage of Healthy Eyes Using Optical Coherence Tomography Angiography

Background and objectives: Ocular massage (OM) is used as a treatment option for acute retinal artery occlusion, under the assumption that it induces vessel dilatation and enhances perfusion. Since evidence of ocular perfusion alteration due to OM is lacking, we investigate the impact of OM on the hemodynamics of the posterior pole in healthy eyes in a noninvasive fashion by using optical coherence tomography angiography (OCTA). Materials and Methods: A prospective study was conducted on healthy volunteers, each of whom underwent measurements of intraocular pressure (IOP), central macular thickness (CMT), subfoveal choroidal thickness (SFCT), radial peripapillary capillary perfusion (RPCP), superficial capillary plexus perfusion (SCPP), deep capillary plexus perfusion (DCPP), choriocapillaris perfusion (CCP), Sattler’s layer perfusion (SLP) and Haller’s layer perfusion (HLP) before and after OM. OM was performed for 2 min, consisting of 10-s turns of compression and decompression of the globe. Results: A total of 21 eyes from 21 participants (median age 29) were included. After OM, IOP significantly declined (p < 0.001), while SFCT (p < 0.005), SCPP (p < 0.001), DCPP (p = 0.004) and CCP (p = 0.008) significantly increased. CMT, RPCP, SLP and HLP did not show any significant alteration due to OM. Changes in SCPP correlated positively with changes in CCP and vice versa. Conclusions: OCTA-based analysis in healthy adults following OM demonstrated a significant increase of retinal perfusion values, assumed to be due to failure of autoregulatory mechanisms. These findings may indicate a positive effect of OM as a treatment option for patients with acute retinal artery occlusion.

Five-Year Change in Choroidal Thickness in Relation to Body Development and Axial Eye Elongation: The CCC2000 Eye Study

Purpose

We describe changes in choroidal thickness from age 11 to 16 years and its association with ocular biometrics and body development.

Method

In this longitudinal, population-based observational study, choroidal thickness was measured subfoveally and 1- and 3-mm temporal thereof using enhanced depth imaging spectral domain optical coherence tomography. Analyses were stratified by sex and adjusted for age and the time of day that the scan was performed.

Results

The study included 687 participants (304 boys). Median (interquartile range [IQR]) age was 11.5 (0.6) years at baseline and 16.6 (0.3) years at follow-up. Mean increase in choroidal thickness was 33, 27, and 11 μm at the three respective locations. The subfoveal choroid thickened less in eyes whose axial length increased more (boys, β = -85 μm/mm; 95% confidence interval [CI], -104 to -66, P < 0.0001; girls, β = -105 μm/mm; 95% CI, -121 to -89, P < 0.0001) and in eyes with a more negative refractive development (boys, 11 μm/diopters [D]; 95% CI, 4.0 to 18, P = 0.0022; girls, 22 μm/D; 95% CI, 16 to 27, P < 0.0001). Subfoveal choroidal thickness increased less in girls who underwent early puberty (Tanner stage 4 vs. 1; -39 μm' 95% CI, -72 to -5.9, P = 0.021) and who had a longer baseline axial length (β = -8.6 μm/mm; 95% CI, -15 to -2.7, P = 0.0043), and more in girls who grew taller (β = 0.9 μm/cm; 95% CI, 0.1 to 1.7, P = 0.026).

Conclusions

The choroid increased in thickness from age 11 to 16 years. The increase was greater in girls with later sexual maturation and smaller in eyes that added more axial length and had a relatively negative refractive development.

Pulse Waveform Analysis of the Ocular Blood Flow Using Laser Speckle Flowgraphy before and after Glaucoma Treatment

Although reduction in intraocular pressure (IOP) is the principle of glaucoma treatment, impaired ocular blood flow is believed to play a role in the progression of glaucoma. This study evaluated the effect of glaucoma treatment on pulse waveforms for optic nerve head (ONH) microcirculation in patients with glaucoma. Fifty-one subjects were included on the basis of the glaucoma treatment administered, which involved instillation of prostaglandin (PG) analogs (PG group; n = 28) or trabeculectomy (trabeculectomy group; n = 23). ONH blood flow, represented by the mean blur rate (MBR_T) and pulse waveforms, was measured using laser speckle flowgraphy before and 1 and 3 months after treatment. Three months after treatment, IOP exhibited a significant decrease (p < 0.05). Although there was no significant change in MBR_T after treatment, the acceleration time index (ATI) significantly decreased (p=0.034) in the PG group. In the trabeculectomy group, there was no significant change in the MBR_T after treatment, while fluctuation (p=0.019) and blowout score (BOS) (p=0.036) exhibited significant decrease and increase, respectively. Multiple regression analysis showed that mean deviation was significantly associated with the rate of change in the BOS (p=0.013), age was a significant contributing factor for the rate of change in fluctuation in the trabeculectomy group, reflection was significantly associated with the ATI (p=0.037) in the in the PG group. Both glaucoma treatments can change the pulse waveforms, with MBR_T remaining unchanged, and IOP reduction owing to the treatment may contribute to stable blood flow in the tissue area of the ONH. As impaired ocular blood flow plays a role in the progression of glaucomatous damage, it would be beneficial if glaucoma treatment could improve the stability of ONH microcirculation.

Iris Thickness and Severity of Neovascular Glaucoma Determined Using Swept-Source Anterior-segment Optical Coherence Tomography

PURPOSE

To investigate the iris thickness (IT) in neovascular glaucoma (NVG) using swept-source anterior-segment optical coherence tomography (ASOCT).

PATIENTS AND METHODS

In this retrospective, clinic-based, comparative study, we enrolled 20 NVG patients [11 with 360-degree angle-closure (AC)-NVG and 9 with NVG without AC] and 14 healthy age-matched controls. Horizontal scanning images of swept-source ASOCT were analyzed using software calipers in temporal and nasal angle areas. ITs at 1 and 2 mm from the pupil edge were measured using ASOCT. The relation between IT and the severity of NVG, the effects of intraocular pressure (IOP), intravitreal antivascular endothelial growth factor (anti-VEGF) injection, and panretinal photocoagulation (PRP) were assessed using linear regression analysis based on the corrected Akaike information criteria index.

RESULTS

The IT was thinner in 360-degree AC-NVG patients, followed by NVG patients without AC and controls (0.33 vs. 0.48 vs. 0.57 mm at 1 mm and 0.31 vs. 0.43 vs. 0.49 mm at 2 mm; P<0.001 by ANOVA). Multiple linear regression analysis revealed that 360-degree AC-NVG patients-NVG patients without AC and controls (coefficient: -0.16), NVG patients without AC-control (-0.13) and underwent PRP (0.23) at 1 mm, 360-degree AC-NVG patients-NVG patients without AC and controls (-0.12), NVG patients without AC-controls (-0.08), underwent PRP (0.16), received anti-VEGF injection (0.05) and IOP (-0.001) at 2 mm were selected predictors to explain IT.

CONCLUSIONS

IT decreases with the progression of the NVG stage and is thinnest in 360-degree AC-NVG patients. Our study suggests a new morphologic feature of NVG.

Parapapillary Choroidal Microvasculature Dropout Is Associated With the Decrease in Retinal Nerve Fiber Layer Thickness: A Prospective Study

Purpose

To explore the correlation between longitudinal changes of peripapillary retinal nerve fiber layer (RNFL) thickness and the presence of parapapillary choroidal microvasculature dropout (MvD).

Methods

This is a longitudinal cohort study. All patients with normal-tension glaucoma (NTG) were recruited from the Wenzhou Glaucoma Progression Study. The presence of MvD was determined using optical coherence tomography (OCT) angiography and the RNFL thickness was evaluated by spectral-domain OCT. All assessments were performed both at baseline and at every 3-month follow-up for at least 18 months.

Results

Seventy-one eyes were included. The presence of MvD was observed in 23 NTG eyes (32.4%). Eyes with MvD had a thinner RNFL (68.8 ± 9.6 vs. 76.2 ± 16.7 μm, P = 0.016) and a faster rate of RNFL loss (-1.2 ± 1.5 vs. -0.4 ± 1.4 μm/y, P = 0.036) compared with those without MvD. In a univariate analysis of rates of RNFL loss, the presence of MvD at baseline (β = -0.83 ± 0.38, P = 0.033) was significantly associated with progressive RNFL loss. After adjusting for age, female sex, mean follow-up IOP, axial length, central corneal thickness, and mean deviation, the presence of MvD at baseline (β = -0.85 ± 0.41, P = 0.041) was significantly associated with faster rates of RNFL loss in the multivariate analysis.

Conclusions

There is a significant correlation between the presence of MvD and decrease in RNFL thickness in NTG patients. Our study further supported that the presence of MvD is a predictor of longitudinal RNFL damage in glaucoma.

Changes in choroidal area following trabeculectomy: Long-term effect of intraocular pressure reduction

Purpose

To evaluate changes in the macula and peripapillary choroidal area at one year after trabeculectomy in order to determine the effect of intraocular pressure (IOP) changes.

Methods

This prospective longitudinal study examined 30 eyes of 30 patients with glaucoma that was uncontrolled by medical therapy. At 1 day before and at 1 year after the trabeculectomy surgery, macular and peripapillary choroidal images were recorded by enhanced depth imaging optical coherence tomography (EDI-OCT). Luminal and interstitial areas were converted to binary images using the Niblack method. Factors influencing the macular choroidal and peripapillary area were examined by multivariate analysis.

Results

After trabeculectomy, the mean IOP was 10.8±3.2 mmHg compared to 17.8±7.2 mmHg at baseline (P < 0.001). The total macular choroidal area after the surgery increased from 317,735±77,380 to 338,120±90,700 μm², while the interstitial area increased from 108,598±24,502 to 119,172±31,495 μm² (all P < 0.05). The total peripapillary choroidal area after the surgery also increased from 1,557,487±431,798 to 1,650,253±466,672 μm², while the interstitial area increased from 689,891±149,476 to 751,816±162,457 μm² (all P < 0.05). However, there were no significant differences observed in the luminal area before and after the surgery. A decrease in the IOP was among the factors associated with the changes in the peripapillary choroidal area.

Conclusions

IOP reductions after trabeculectomy led to increases in the macular and peripapillary choroidal areas for at least 1 year postoperative. Increases in the interstitial areas were the primary reason for observed changes in the choroidal area after trabeculectomy.

Changes in choroidal thickness and optic nerve head morphology after filtering surgery: nonpenetrating deep sclerectomy versus trabeculectomy

Background

The purpose of this study was to evaluate the changes in choroidal thickness and lamina cribrosa position after nonpenetrating deep sclerectomy (NPDS) and trabeculectomy.

Methods

Twenty-three eyes with glaucoma that required filtering surgery were included (12 NDPS and 11 trabeculectomies) in this prospective observational study. OCT-enhanced depth imaging (OCT-EDI) was used to measure choroidal thickness, prelaminar tissue thickness and lamina cribrosa position before and 7 days and 1 month after surgery. All results are shown as median (interquartile range values).

Results

Intraocular pressure (IOP) was significantly lower 1 week after surgery than at baseline (7 (6/10) mmHg vs. 21 (18/26) mmHg; p < 0.001) with a mean 64% decrease. IOP remained significantly lower at 1 month with a 55% mean decrease as compared to baseline (10 (8/12) mmHg; p < 0.001). One week after surgery, the subfoveolar choroidal thickness (SFCT) significantly increased (372 (306/523) μm vs. 317 (227/413) μm; p = 0.04) and the prelaminar tissue (PLT) was significantly thicker (269 (162/360) μm vs. 138 (87/268) μm; p = 0.02) as compared to preoperative measurements. These changes were not statistically significant at one month. There were no differences concerning these parameters between the NPDS and trabeculectomy groups. During the first week, the SFCT increase was correlated with IOP reduction (r = − 0.41; p = 0.04).

Conclusions

OCT-EDI allowed the visualization of structural changes at the level of the optic nerve and choroidal vascularization during acute IOP changes. No difference was observed between NPDS and trabeculectomy concerning these structural modifications.

Changes in choroidal area after intraocular pressure reduction following trabeculectomy

Purpose

To investigate changes of the macular and peripapillary choroidal areas after trabeculectomy.

Methods

This prospective and interventional study examined 74 eyes of 74 patients with glaucoma uncontrolled by medical therapy. Enhanced depth imaging optical coherence tomography (EDI-OCT) recorded macular and peripapillary choroidal images at 1 day before trabeculectomy and at 2 weeks after surgery. The Niblack method was used to covert luminal and interstitial areas to binary images.

Results

At baseline, the mean intraocular pressure (IOP) was 17.6±6.3 mmHg, while it was 6.5±2.9 mmHg after trabeculectomy (P < 0.001). Increases were observed for the macular choroidal area after the surgery, with the total area increasing from 317,853±95,728 μm² to 368,597±104,393 μm², while the luminal area increased from 210,355±73,650 μm² to 249,464±77,195 μm², and the interstitial area increased from 107,498±27,613 μm² to 119,133±31,811 μm² (all P < 0.001). Increases were also observed after the surgery for the peripapillary choroidal area, with the total area increasing from 1,629,440±460,429 μm² to 1,974,289±500,496 μm², while the luminal area increased from 920,141±328,690 μm² to 1,179,843±357,601 μm², and the interstitial area increased from 709,299±153,179 μm² to 794,446±169,029 μm² (all P < 0.001). There was a significant increase in the ratio of the luminal to choroidal area in the macular area (67.2%) and in the peripapillary area (59.1%). Factors associated with the changes in the peripapillary choroidal area included decreases in the diastolic blood pressure and IOP.

Conclusions

A reduction in the IOP after trabeculectomy led to increases in the macular and peripapillary choroidal areas. Observed changes in the choroidal area after trabeculectomy are primarily due to increases in the luminal areas.