Intraocular pressure elevation and choroidal thinning

Choroidal manifestations of non-ocular sarcoidosis: an enhanced depth imaging OCT study

BACKGROUND

Although choroidal thickening was reported as a sign of active inflammation in ocular sarcoidosis, there has been no research on the choroidal changes in non-ocular sarcoidosis (defined as systemic sarcoidosis without overt clinical signs of ocular involvement). Therefore, this study aimed to investigate choroidal structural changes in patients with non-ocular sarcoidosis.

METHODS

This retrospective case-control study was conducted at Asan Medical Center, a tertiary referral center. We evaluated 30 eyes with non-ocular sarcoidosis and their age- and spherical equivalent-matched healthy control eyes. The subfoveal choroidal thickness, area ratio (Sattler layer-choriocapillaris complex [SLCC] area to Haller layer [HL] area), and choroidal vascularity index (CVI, luminal area to choroidal area) were analyzed using enhanced depth imaging in optical coherence tomography. Systemic and ocular factors associated with the choroidal thickness were investigated.

RESULTS

Compared with the healthy control group, the non-ocular sarcoidosis group had significantly thicker subfoveal choroid (total and all sublayers [SLCC and HL]) and lower area ratio. There were no significant differences in the CVIs at all sublayers between groups. In the non-ocular sarcoidosis group, eyes under oral steroid treatment had thinner choroid than eyes under observation. In the control group, eyes with older age and more myopic spherical equivalent had thinner choroidal thickness.

CONCLUSION

Total and all sublayers of the subfoveal choroid were significantly thicker without significant vascularity changes in non-ocular sarcoidosis eyes than in healthy control eyes. The degree of choroidal thickening was disproportionally greater at HL than at SLCC. These characteristic choroidal changes may be the subclinical manifestations in non-ocular sarcoidosis.

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.

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.

Choriocapillaris Flow Deficits in Normal Chinese Imaged by Swept-Source Optical Coherence Tomographic Angiography

PURPOSE

To evaluate the ocular and systemic determinants of the choriocapillaris flow deficits percentage (CC FD%) in normal eyes.

DESIGN

Observational cross-sectional study.

METHODS

Healthy Chinese participants without ocular or systemic diseases underwent detailed ophthalmic evaluations, including swept-source optical coherence tomography angiography (SS-OCTA) with 6- × 6-mm macular choriocapillaris images. The CC FD% was assessed in circular regions with diameters of 1.0 and 5.0 mm, rings with 1.0- to 2.5-mm diameters, and rings with 2.5- to 5.0-mm diameters.

RESULTS

The study included 830 individuals (mean ± SD age 58.66 ± 8.75 years). CC FD% (mean ± SD 22.05% ± 1.13%) was the lowest in the 2.5- to 5.0-mm ring, followed by the 1.0- to 2.5-mm ring, and highest in the 1.0-mm circle. In multivariable analysis, a higher CC FD% was associated with older age (β = 0.16 [95% confidence interval {CI}] 0.08-0.24, P < .001), higher intraocular pressure (β = 0.34 [95% CI 0.25-0.42], P < .001), higher serum concentrations of high-density lipoprotein cholesterol (β = 0.24 [95% CI 0.17-0.32], P < .001), and lower image quality score (β = -0.22 [95% CI -0.30 to -0.14], P < .001). CC FD% was also independent of axial length.

CONCLUSIONS

In healthy adult Chinese individuals, a higher CC FD% was associated with older age, higher intraocular pressure, and higher high-density lipoprotein cholesterol serum concentration. These factors may influence clinical assessments of the choriocapillaris. The lack of an association between CC FD% and axial length is consistent with similar findings for Bruch membrane thickness, macular retinal thickness, and macular retinal pigment epithelium cell density.

Correlation between choroidal thickness and intraocular pressure control in primary angle-closure glaucoma

Purpose:

To study the correlation between choroidal thickness (CT) and IOP control in primary angle-closure glaucoma (PACG).

Methods:

In total, 61 patients (102 eyes) with PACG underwent subfoveal CT (SFCT) scanning using enhanced depth imaging–optical coherence tomography. The subjects with PACG were further grouped as controlled IOP (≤21 mm Hg on maximal medical therapy) and uncontrolled IOP (>21 mm Hg on maximal medical therapy). The average CT of the PACG eyes was calculated and compared between both groups. A correlation analysis was done between CT and intereye difference in CT with the disease parameters.

Results:

The mean CT was 274.38 ± 42.10 μm in 102 PACG eyes. SFCT was significantly increased in the uncontrolled IOP group as compared with the controlled IOP group. The mean SFCT was 245.57 ± 62.10 μm in the controlled group and 294.46 ± 51.05 μm in the uncontrolled group (P < 0.01). Factors associated with a thicker choroid were younger age, high IOP, and higher optic nerve head cupping (P < 0.001). Neither the visual field-mean deviation (VF-MD) nor pattern standard deviation (PSD) was found to be associated with overall CT. The intereye asymmetry between CT was significantly associated with poor VF-MD and PSD.

Conclusion:

PACG eyes with thicker choroid may be a risk factor for poor IOP control on medical anti-glaucoma therapy. Thicker choroid as compared to the fellow eye is a poor prognostic sign and these eyes should be monitored closely.

Retinal Changes before and after Silicone Oil Removal in Eyes with Rhegmatogenous Retinal Detachment Using Swept-Source Optical Coherence Tomography

This study aimed to evaluate and compare the retinal and choroidal thickness and vessel density (VD) changes between silicone oil (SO) tamponade and after SO removal using swept-source optical coherence tomography (SS-OCT) and OCT angiography (OCTA). Thirty patients who underwent pars plana vitrectomy for retinal detachment (RD) with SO tamponade were included. SS-OCT and OCTA were conducted before RD surgery, during SO tamponade, and after SO removal. A 3-dimensional volumetric wide scan protocol was used for the analysis. The segmented retina, choroidal thickness map, and peripapillary thickness were then measured. For the OCTA analysis, 4.5 × 4.5 mm scans were used. Superficial and deep capillary plexus VDs in unaffected fellow eyes and eyes after SO removal were compared. During the SO tamponade period, the thickness of the parafoveal total retina, ganglion cell-inner plexiform layer, and peripapillary retinal nerve fiber layer (ppRNFL) were significantly thinner than those of unaffected fellow eyes (p < 0.05). The parafoveal layer thickness thinning recovered up to three to six months after SO removal. Moreover, six months after SO removal, the parafoveal thickness was not significantly different compared to that of unaffected fellow eyes (p > 0.05). However, the ppRNFL thickness was significantly decreased during SO tamponade and remained unrecovered six months after SO removal. There was no significant difference in the VD on the OCTA. Thus, SO tamponade and removal for RD resulted in a change in the retinal and peripapillary thickness. This may be due to the mechanical pressure effect of SO.

Morphometrical analysis of the canine choroid in relation to age and sex using spectral domain optical coherence tomography

This study determined the choroidal thickness of senior (SN, n = 24) and middle-aged (MA, n = 17) healthy, mixed-breed mesocephalic dogs, both males (M) and females (F), using spectral domain optical coherence tomography (SD-OCT). The dogs were divided into two groups for examination: MA dogs (4-7 years old; 6 M, 11 F) and SN dogs (8-13 years old; 12 M, 12 F). Choroidal thickness of the dogs was investigated using SD-OCT radial and linear scans. The software of the device allowed determination of the exact measurement location on the choroid. Measurements of the choroid were taken manually using the SD-OCT calliper function at distances of 5,000-6,000 μm (dorsal and ventral) and 4,000-7,000 μm (nasal and temporal) from the optic disc. Mean (µm ± SD) (MA, SN) dorsal (188 ± 28, 184 ± 33), ventral (116 ± 23, 111 ± 16), temporal (152 ± 31, 151 ± 26), and nasal (135 ± 27, 132 ± 18) choroidal thicknesses demonstrated significant differences (P < 0.02-0.001) between all areas within each group. The choroid was thickest in the dorsal region and thinnest in the ventral region. There were no significant differences based on age. Mean (µm ± SD) (M, F) dorsal (181 ± 32, 190 ± 30), ventral (117 ± 16, 11 ± 21), temporal (150 ± 26, 153 ± 30), and nasal (128 ± 20, 138 ± 23) choroidal thicknesses demonstrated significant differences (P < 0.05) between dorsal and nasal regions. The choroidal thickness in dogs depends on the area assessed independently of their age and sex.

The Association of Acute Cerebrospinal Fluid Pressure Reduction with Choroidal Thickness

PURPOSE

To investigate the changes in choroidal thickness (CT) after acute cerebrospinal fluid pressure (CSFP) reduction in human subjects.

METHODS

Before and 15 minutes after diagnostic lumbar puncture (LP), 44 patients underwent measurement of CT by swept-source optical coherence tomography. Thirty-two healthy volunteers imitated the body posture of LP procedure and underwent the same measurement before and 15 minutes after body posture change.

RESULTS

After CSFP reduction from 10.9 ± 2.1 mmHg at baseline to 8.1 ± 1.5 mmHg (p < 0.001), CT decreased in subfoveal region (p = 0.005), small to medium vessel layer (SMVL, p < 0.001), peripapillary regions in temporal (p = 0.001), nasal (p < 0.001), superior (p < 0.001) and inferior (p < 0.001), respectively. However, no significant change in CT in the control group after body posture change (all p > 0.05). A significant association between CSFP and the ratio of small to medium vessel layer to total choroidal thickness was found (p = 0.009). The CSFP reduction rate was associated with the change rate of SMVL to total CT portion, for each percent decrease in CSFP was associated with a decrease by 0.22% in the rate of SMVL to total CT portion (R² = 0.125, p = 0.018).

CONCLUSIONS

A significant decrease in subfoveal CT, small to medium vessel layer and peripapillary region were observed following acute CSFP reduction. The CSFP reduction rate was associated with the change rate of small to medium vessel layer to total CT portion.

How does nepafenac affect the choroidal thickness after uneventful cataract surgery?

PURPOSE

To investigate the effects of topical nepafenac on choroidal thickness (CT) following uneventful phacoemulsification surgery (UPS) using enhanced depth imaging optical coherence tomography (EDI-OCT).

METHODS

This prospective study included 45 randomly selected eyes (23 eyes of 23 patients used nepafenac (nepafenac group) and 22 eyes of 22 control patients did not use nepafenac (nepafenac-free group)) undergoing small-incision UPS. All participants underwent full ophthalmologic examination. CT measurements were performed at subfoveal, 1.0 mm temporal, and 1.0 mm nasal using the EDI-OCT preoperatively, 1 day, 1 week, and 1 month postoperatively.

RESULTS

The mean subfoveal, nasal, and temporal CT in the nepafenac-free group had changed from 268.95 ± 63.59 μm to 283.36 ± 65.63 μm, 237.22 ± 64.09 μm to 253.09 ± 67.27 μm, and 235.95 ± 75.22 μm to 259.09 ± 63.66 μm preoperatively to 1 month postoperatively, respectively (p < 0.001, p < 0.001, p < 0.001, respectively). The mean subfoveal, nasal, and temporal CT in the nepafenac group had changed from 259.65 ± 55.99 μm to 276.65 ± 59.21 μm, 236.34 ± 55.40 μm to 251.00 ± 62.39 μm, and 247.56 ± 50.88 μm to 261.13 ± 53.73 μm preoperatively to 1 month postoperatively, respectively (p < 0.001, p < 0.001, p < 0.001, respectively). The postoperative CT continued to increase significantly during the follow-up period in two groups. However, compared to the change from baseline to month 1, there was not a statistically significant difference between the groups at subfoveal, nasal, and temporal CT (p: 0.633, p: 0.865, and p: 0.328, respectively).

CONCLUSION

UPS may cause a significant increase in CT. Although increasing in the CT was lower in the nepafenac group than the nepafenac-free group, there was not a statistically significant difference between the groups.

Localization in Glaucomatous Visual Field Loss Vulnerable to Posture-Induced Intraocular Pressure Changes in Open-Angle Glaucoma

PURPOSE

To investigate localization in glaucomatous visual field defects that are vulnerable to posture-induced intraocular pressure (IOP) changes.

DESIGN

Prospective cross-sectional study.

METHODS

Ninety-three eyes of 93 newly diagnosed cases with normal tension glaucoma were examined. The IOP was measured in both the sitting and lateral decubitus positions with an Icare rebound tonometer. Visual field tests were performed with a Humphrey Field Analyzer with the Central 30-2 program using Swedish Interactive Threshold Algorithm standard strategies. The total deviation (TD) map values of 51 tested points were used for the analysis. A regression analysis was conducted to investigate relationships between TD in each point or cluster and posture-induced IOP changes. A linear mixed-effects model was used to identify factors associated with TD changes in each visual field cluster. Main outcome measures included the relationship between posture-induced IOP changes and localization of visual field defects.

RESULTS

There were 54 women and 39 men (mean age, 53.4 ± 12.5 years). The mean IOP per Icare rebound tonometer was 15.5 ± 3.2 mm Hg in the sitting position and 18.8 ± 3.1 mm Hg in the lateral decubitus position. The postural IOP difference was 3.3 ± 1.8 mm Hg (P < .001; range, -1.0 to 7.7 mm Hg). There was a significant negative correlation between TD and posture-induced IOP changes in 4 contiguous central points located just above the horizontal meridian. A linear mixed-effects model revealed a significant association between the difference in postural IOP change and decreased TD in the superior paracentral visual field according to multivariate analysis (P = .010).

CONCLUSIONS

Posture-induced IOP variations have been shown to be associated with glaucomatous superior paracentral visual field defects.

Neuroretinal rim response to transient changes in intraocular pressure in healthy non-human primate eyes

Optic nerve head (ONH) neuroretinal rim thickness, quantified as minimum rim width (BMO-MRW), is a sensitive measure for assessing early glaucomatous disease. The BMO-MRW is sensitive to transient fluctuations in intraocular pressure (IOP), but the time course over which BMO-MRW decreases and recovers with changes in IOP remains unknown. The goal of this study was to investigate the dynamics of BMO-MRW changes over 2-h periods of mild or moderate IOP elevation, and subsequent recovery, in healthy non-human primate eyes. Eight non-human primates were included in the study. For each animal, in two different sessions separated by at least 2 weeks, the anterior chamber IOP of one eye was maintained at either 25 mmHg or 40 mmHg for 2 h and, subsequently, at 10 mmHg for 2 h. For the duration of anterior chamber cannulation, optical coherence tomography (OCT) radial scans centered on the ONH were acquired every 5 min and used to quantify BMO-MRW. An exponential decay or rise to maximum function was used to determine the extent and rate of structural change. Additionally, Bruch's membrane opening (BMO) area, BMO height/displacement, and BMO-referenced anterior lamina cribrosa surface depth (BMO-ALCSD) were computed from radial scans. A circular scan was used to quantify retinal nerve fiber layer thickness (RNFLT) and circumpapillary choroid thickness. The primary results demonstrated that the BMO-MRW changed over an extended duration, while BMO displacement was rapid and remained stable with sustained IOP. The mean maximum predicted BMO-MRW thinning following 2 h of IOP elevation was significantly related to pressure (34.2 ± 13.8 μm for an IOP of 25 mmHg vs 40.5 ± 12.6 μm for 40 mmHg, p = 0.03). The half-life for BMO-MRW thinning was 21.9 ± 9.2 min for 25 mmHg and 20.9 ± 4.2 min for 40 mmHg, not significantly different between IOP levels (p = 0.76). Subsequently, after 2 h of IOP at 10 mmHg, all animals exhibited partial recovery of BMO-MRW with similar degrees of persistent residual thinning for the two IOP levels (21.5 ± 13.7 vs 21.0 ± 12.3 μm, p = 0.88). Similar to BMO-MRW, choroid thickness exhibited gradual thinning with IOP elevation and residual thinning following IOP reduction. However, there was no significant change in BMO area or BMO-ALCSD in either experimental session. The RNFLT gradually decreased over the duration of IOP elevation, with continued decreases following IOP reduction for the 40 mmHg session, resulting in total changes from baseline of -2.24 ± 0.81 and -2.45 ± 1.21 μm for 25 and 40 mmHg, respectively (p < 0.001). The sum of the results demonstrate that the ONH neural tissue is sensitive to changes in IOP, the effects of which are gradual over an extended time course and different for increased vs. decreased pressure. Understanding the duration over which IOP influences BMO-MRW has important implications for studies investigating the effects of IOP on the ONH. Additionally, individual variability in ONH response to IOP may improve our understanding of the risk and progression of disease.

EDI-OCT choroidal thickness in Posner-Schlossman syndrome

PURPOSE

To compare the choroidal thickness (CT) of the affected eyes with the contralateral eyes in the active period and in the remission period in Posner-Schlossman syndrome (PSS) using EDI-OCT.

PATIENTS AND METHODS

This prospective longitudinal study included 15 patients with PSS and 15 age- and sex-matched healthy subjects. All subjects underwent complete ophthalmologic examinations, and EDI-OCT was conducted to measure macular CT (mCT) at the subfoveal locations and at 0.5, 1.0 and 2.0 mm superior, inferior, nasal and temporal to the fovea. The mean measurements at each location were used for analysis. Linear regression analysis was performed to analyse the correlation between the choroidal thickness and IOP, and the correlation between the choroidal thickness and episode time.

RESULTS

The mean mCT was significantly thinner in affected eyes than in contralateral eyes in the acute phase (p = 0.010) but were not different in the remission phase (p = 0.404). The mean mCT was significantly increased in the remission phase compared to that in the acute phase in the affected eyes (p = 0.000). The mCT of healthy subjects was significantly thicker than in the affected eyes (p = 0.020) and similar to the fellow eyes of PSS patients (p = 0.357) in the acute phase. Linear regression analyses show negative correlations between the mCT changes and IOP changes in the affected eyes compared to those in the fellow eyes in the acute period (R² = 0.396, p = 0.033) and between the mCT changes and IOP changes from the acute period to the remission period in the affected eyes (R² = 0.372, p = 0.027). Linear regression analyses show positive correlations (age- and sex-matched) between the CT changes and episode time from the affected eyes to the fellow eyes in the acute period (R² = 0.492, p = 0.012).

CONCLUSIONS

The mCT values of the PSS-affected eyes were significantly thinner than those of the fellow eyes in the acute phase and in the remission phase, and this change was correlated with IOP reduction and episode time.

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.

Upside-down position leads to choroidal expansion and anterior chamber shallowing: OCT study

Background

To determine whether dynamic changes in choroidal thickness (CT) cause shallowing of the anterior chamber.

Methods

34 healthy volunteers were enrolled. The participants in our study adopted the upside-down position for 1.5 min, which was the model we used to study the dynamic changes in CT. Intraocular pressure (IOP) elevation, optical coherence tomography images of the choroid and anterior chamber were obtained at baseline, after being in an upside-down position in an inversion machine and after 15 min of rest. The changes in IOP, anterior chamber and choroidal blood flow between the baseline and the upside-down position were compared.

Results

Sixty-eight eyes from 34 subjects were analysed. After being in upside-down position for 1.5 min, there was a significant increase in CT from 226.39±52.44 µm to 238.34±54.84 µm (p<0.001). Choroidal flow index decreased from 0.3357±0.0251 to 0.3004±0.0190 in upside-down position, and there was a decrease in anterior chamber depth (3.21±0.22 mm to 3.13±0.21 mm, p<0.001) and angle opening distance at 500 µm from the scleral spur (0.65±0.24 mm to 0.58±0.20 mm, p=0.007). Pearson correlation analysis showed that the increase in CT was positively related with CT at baseline CT (p=0.001).

Conclusion

When the body position changed from sitting to upside-down position, there was choroidal thickening, anterior chamber shallowing and IOP elevation with reduced choroidal blood flow. The data provide evidence about the relationship between choroid expansion and shallowing of the anterior chamber, which may be of relevance for the pathogenesis of angle closure.

Changes in vessel density of the patients with narrow antenior chamber after an acute intraocular pressure elevation observed by OCT angiography

Background

Although the pathogenesis of glaucoma is not fully understood,an elevated intraocular pressure (IOP) is a major factor contributing to its development and progression. The aim of this study was to investigate the changes in the vessel densities of the macula and optic nerve head (ONH) after an acute elevation in the intraocular pressure (IOP) observed using optical coherence tomography angiography (OCTA).

Methods

This was a prospective comparative study of subjects with narrow anterior chamber angles who underwent laser peripheral iridotomies (LPIs). The IOP was measured before and one hour after the LPI. The retinal vessel densities of the macula and ONH were measured using OCTA at the baseline and one hour after the LPI.

Results

A total of 64 eyes of 51 individuals were enrolled in this study, and 58 eyes of 43 individuals finally completed the study with a mean IOP rise of 10.5 ± 7.6 mmHg after the LPI. Based on the magnitude of the rise in the IOP, we divided the subjects into three groups: group A = IOP rise ≤10 mmHg, group B = 10 mmHg < IOP rise ≤20 mmHg, and group C = IOP rise > 20 mmHg. The vessel density did not differ after the acute IOP elevation in either the macular region or papillary region in group A or group B (p > 0.05), but there was a significant difference in group C (p < 0.05). However, when the subjects were not separated into groups, the vessel densities of the ONH and macular region did not differ between the measurements obtained at the baseline and one hour after the LPI (p > 0.05). The correlation existed in peripapillary and macular vessel density (p < 0.05).

Conclusion

In these subjects with narrow antenior chamber, an acute mild or moderate IOP elevation for one hour after the LPI did not affect the vessel density in the macula or ONH, as examined using OCTA. However, when the IOP rise was greater than 20 mmHg, the macular and papillary vessel density decreased significantly.

Optical Coherence Tomography Angiography Vessel Density Changes after Acute Intraocular Pressure Elevation

To investigate changes in retinal vessel density in optic nerve head (ONH) and macula after acute intraocular pressure (IOP) elevation, we conducted a prospective observational study. Eyes with IOP rise ≥5 mmHg after 2-hour dark room prone provocative test (DRPPT) were included. Vasculature of ONH and macula was examined by optical coherence tomography angiography (OCTA) at baseline and after DRPPT. Among the 65 eyes of 42 individuals, 40 eyes with qualified images were enrolled. Mean IOP rise was 9.6 ± 4.2 mmHg (5.0-23.3 mmHg) after DRPPT. Retinal vessel density did not differ after IOP rise for either the papillary region (optic nerve head and radial peripapillary capillary layer) or the macula region (superficial, deep and outer retinal layer) (P > 0.05). Vessel density in each subregion did not change either. If only enrolled eyes with IOP rise ≥10 mmHg, similar results were obtained in condition of IOP increase by 15.0 ± 3.6 mmHg. To conclude, eyes with an acute IOP elevation by 10 or 15 mmHg for two hours, while the blood pressure remained constant, the vessel density in both ONH and macula region examined by OCTA did not show significant changes. The observations fit with an IOP-related autoregulation in retinal blood flow for a moderate elevation of IOP.

The effects of graded intraocular pressure challenge on the optic nerve head

Intraocular pressure (IOP) is an important risk factor for glaucoma, and the response of the ONH and surrounding tissues to elevated IOP are often investigated to better understand pathophysiology. In vivo structure including that of the optic nerve head (ONH) and surrounding tissue of the eye are often assessed using optical coherence tomography (OCT). With advances in OCT technology, both large vessels and capillaries can be imaged non-invasively (OCT Angiography). Because a significant portion of retinal thickness is comprised of vasculature, the purpose of the current study was to investigate OCT structural and vascular changes in healthy non-human primate eyes with systematic graded increases and decreases in IOP. Six healthy animals with no previous experimental intervention were used. The pressure in the anterior chamber was adjusted from 10 mmHg to 60 mmHg and back to 10 mmHg in 10 mmHg steps every 10 min. Using optical coherence tomography (OCT), retinal nerve fiber layer (RNFL) thickness, minimum rim width (MRW), Bruch's membrane opening (BMO) size and relative height, anterior lamina cribrosa surface (ALCS) depth, choroidal thickness, and angiography (OCTA) were quantified. With IOP challenge there were significant changes in all morphological measures quantified (p < 0.01) other than BMO size (p = 0.30) and RNFL thickness (p = 0.29). Specifically, the position of the BMO was sensitive to both an increase and decease in IOP. The inner retinal capillary density gradually decreased with increasing IOP, reaching statistical significance when pressure exceeded 50 mmHg, but returned when IOP was reduced. The average choroidal thickness around the ONH decreased for elliptical annuli 500-1000 μm and 1000-1500 μm, from the BMO, with increasing IOP (p < 0.01). For the 1000-1500 μm annulus, choroid thickness did not return to baseline with IOP reduction. Similarly, the MRW decreased with increase in IOP, but with pressure reduction did not return, and at the final 10 mmHg time point was thinner than at baseline (p < 0.01). The results from this experiment illustrate differences in ONH neural rim tissue, RNFL and vessel density changes with acute IOP challenge. Overall, vessel collapse could not completely account for changes in RNFL or ONH MRW thickness. The study supports the hypothesis neural rim compression may be an important part of IOP-induced damage.

Macular Choroidal Small-Vessel Layer, Sattler's Layer and Haller's Layer Thicknesses: The Beijing Eye Study

To study macular choroidal layer thickness, 3187 study participants from the population-based Beijing Eye Study underwent spectral-domain optical coherence tomography with enhanced depth imaging for thickness measurements of the macular small-vessel layer, including the choriocapillaris, medium-sized choroidal vessel layer (Sattler’s layer) and large choroidal vessel layer (Haller’s layer). In multivariate analysis, greater thickness of all three choroidal layers was associated (all P < 0.05) with higher prevalence of age-related macular degeneration (AMD) (except for geographic atrophy), while it was not significantly (all P > 0.05) associated with the prevalence of open-angle glaucoma or diabetic retinopathy. There was a tendency (0.07 > P > 0.02) toward thinner choroidal layers in chronic angle-closure glaucoma. The ratio of small-vessel layer thickness to total choroidal thickness increased (P < 0.001; multivariate analysis) with older age and longer axial length, while the ratios of Sattler’s layer and Haller’s layer thickness to total choroidal thickness decreased. A higher ratio of small-vessel layer thickness to total choroidal thickness was significantly associated with a lower prevalence of AMD (early type, intermediate type, late geographic type). Axial elongation-associated and aging-associated choroidal thinning affected Haller’s and Sattler’s layers more markedly than the small-vessel layer. Non-exudative and exudative AMD, except for geographic atrophy, was associated with slightly increased choroidal thickness.

SD-OCT Choroidal Thickness in Advanced Primary Open-Angle Glaucoma

PURPOSE

To assess the choroidal thickness in advanced primary open-angle glaucoma (POAG) comparing patients affected by advanced glaucoma and normal subject using spectral domain optical coherence tomography (SD-OCT).

METHODS

In total, 35 eyes of 35 patients affected by POAG with advanced perimetric defect (mean deviation worse than -12 dB) were prospectively enrolled and underwent a complete ophthalmologic examination, including enhanced depth imaging SD-OCT. One eye of 35 healthy subjects served as control group. Choroidal thickness was measured at the subfoveal location, at 0.5, 1.0, and 2.0 mm nasal and temporal to the fovea. Primary outcome measure was the identification of different choroidal thickness between advanced glaucoma patients and normal subjects.

RESULTS

Glaucoma and control group were homogenous for age, sex, and axial length (P>0.05 in all cases). A significant difference was found in the subfoveal choroidal thickness (SFCT) adjusted for age and axial length between glaucoma and control eyes (P=0.042); in glaucoma patients the mean adjusted SFCT was 209.90 μm compared with 234.78 μm in control subjects. Both temporal and nasal choroidal thickness measurements followed the same SFCT trend, even if only temporal ones were statistically significant. We also found that SFCT decreased with age and increased axial length (P=0.007 and 0.001, respectively). Sex and intraocular pressure did not significantly influence the choroidal thickness (P=0.87 and 0.35, respectively).

CONCLUSIONS

Patients affected by advanced POAG damage have a thinner choroidal thickness compared with normal subjects, using SD-OCT. We also confirmed that age and axial length were the main factors affecting choroidal thickness in these patients.

Choroidal Thickness in Women with Uncomplicated Pregnancy: Literature Review

Pregnancy is a time when many changes occur in a woman's body. The goal of these changes is the provision of optimum conditions for the development of the foetus. Pregnancy also affects eye physiology. Well recognized physiological changes include a reduced corneal sensitivity, an increase in its central thickness and curvature, and a decrease in intraocular pressure. The association between choroidal thickness and pregnancy is not clear. Haemodynamic and hormonal changes taking place during pregnancy and the question of whether these changes are reflected by choroidal thickness are especially important. It is assumed that the choroid, which is one of the most highly vascularized tissues characterized by the highest blood flow to tissue volume ratio in the whole body, should respond by an increase in its thickness to an increase in blood flow and drop in the value of peripheral resistance. Measurement of choroidal thickness using enhanced depth imaging optical coherence tomography (EDI-OCT) in women with uncomplicated pregnancy provides important information concerning the effects of physiological changes in the eye.

A Randomized Controlled Trial Comparing Outcomes of Cataract Surgery in Nanophthalmos With and Without Prophylactic Sclerostomy

PURPOSE

To prospectively evaluate visual outcomes and complications during and after cataract surgery with or without prophylactic sclerostomy in nanophthalmic eyes with visually significant cataract.

STUDY DESIGN

Randomized controlled trial.

METHODS

Sixty nanophthalmic eyes of 60 patients with visually significant cataract were randomly assigned to cataract surgery alone (control group, n = 31) or cataract surgery with concomitant prophylactic sclerostomy (sclerostomy group, n = 29). Surgery was performed using phacoemulsification or manual small-incision cataract surgery (SICS) based on the LOCS III grading score. Group differences in intraoperative and postoperative complications were analyzed and risk factors assessed.

RESULTS

Fewer complications were noted in eyes receiving sclerostomy (5/29, 17.2%) as compared to control group eyes (12/31, 38.7%), though differences were marginally significant (P = .065). Four control group, but no sclerostomy group, eyes developed postoperative uveal effusions (P = .04). In multivariable models, sclerostomy decreased the odds of an intraoperative or postoperative complication by 80% (odds ratio [OR] = 0.2, 95% confidence interval [CI] = 0.04-0.92, P = .039); SICS was associated with a significantly higher risk of complications as compared to phacoemulsification (OR = 5.95, 95% CI = 1.49-23.73, P = .012), while high preoperative intraocular pressure (OR = 4.54, 95% CI = 0.99-20.9, P = .052) and greater lens thickness (OR = 3.38, 95% CI = 0.88-12.91, P = .075) demonstrated a marginally significant association.

CONCLUSIONS

Cataract surgery in eyes with nanophthalmos is associated with a high risk for vision-threatening complications. Performing a simultaneous prophylactic sclerostomy with cataract surgery reduces complication rates, particularly uveal effusions. Cataract surgery at earlier stages by phacoemulsification may be more beneficial than undergoing manual SICS.

Peripapillary choroidal vascular layers: the Beijing Eye Study

PURPOSE

To assess thickness and associations of the peripapillary choroidal layers.

METHODS

The population-based Beijing Eye Study included 3468 participants with an age of 50+ years. Using spectral-domain optical coherence tomography, we measured the large vessel layer (LVL) and small-to-medium vessel layer (SMVL) of the peripapillary choroid in a circular scan with a diameter of 3.4 mm around the optic nerve head centre at eight locations equidistant (45°) to each other. The ratio of SMVL thickness to LVL thickness was calculated.

RESULTS

Measurements were available for 3000 (86.5%) study participants (mean age: 64.4 ± 9.6 years; range: 50-93 years). SMVL (mean thickness: 31 ± 7 μm; range: 17-70 μm) and LVL (103 ± 48 μm; range: 9-313 μm) were thickest superiorly, followed by the temporal region, nasal region, and inferior region. Thicker SMVL was associated (regression coefficient r: 0.33) with younger age (p < 0.001; standardized regression coefficient β: -0.26), higher cognitive function (p = 0.02; β: 0.05), shorter axial length (p < 0.001; β: -0.12), thicker lens (p < 0.001; β: 0.07), smaller disc area (p < 0.001; β: -0.08), smaller parapapillary β/γ zone (p < 0.001; β: -0.10) and lower prevalence of angle-closure glaucoma (p = 0.04; β: -0.04). Thicker LVL thickness was correlated (r: 0.45) with younger age (p < 0.001; β: -0.34) and higher cognitive function (p = 0.01; β: 0.05), shorter axial length (p < 0.001; β: -0.09)), thicker lens (p = 0.009; β: 0.06), smaller disc area (p < 0.001; β: -0.09), smaller parapapillary alpha zone (p = 0.04; β: -0.04), smaller β/γ zone (p < 0.001; β: -0.14) and lower prevalence of angle-closure glaucoma (p = 0.057; β: -0.04). A higher SMVL-to-LVL thickness ratio was related with older age (p < 0.001; β: 0.36), longer axial length (p < 0.001; β: 0.09), lower best-corrected visual acuity (BCVA) (p = 0.002; β: 0.07), larger optic disc area (p < 0.001; β: 0.10) and larger β/γ zone (p < 0.001; β: 0.19).

CONCLUSION

Small-to-medium vessel layer (SMVL) and LVL, thickest superiorly and thinnest inferiorly, increased with younger age and higher cognitive function after adjusting for axial length and prevalence of angle-closure glaucoma. With older age, longer axial length, larger optic disc area and larger β zone, LVL decreased more than SMVL in thickness. The association between thicker peripapillary choroidal thickness and better cognitive function may deserve further attention.

Choroidal thickness in school children: The Gobi Desert Children Eye Study

Purpose

To investigate choroidal thickness (CT) and its associations in children in a school-based study.

Methods

The cross-sectional school-based Gobi Desert Children Eye Study included 1565 out of 1911 (81.9%) eligible children from all schools in the oasis region of Ejina in the Gobi Desert. A detailed ophthalmic examination was performed, including spectral-domain optical coherence tomography with enhanced depth imaging for CT measurement.

Results

CT measurements were available for 1463 (93.5%) students (mean age: 11.8±3.5 years; range:7–21 years). Mean subfoveal choroidal thickness (SFCT) was 282±49μm. CT was thickest at 1000μm temporal to the fovea (286±49μm), followed by the subfoveal region (282±49 μm; P<0.001), the region at 2500μm temporal to the fovea (278±49μm), the region at 1000μm nasal to the fovea (254±49μm;P<0.001), and the region at 2500μm nasal to the fovea (197±50μm;P<0.001). In cross-sectional analysis, the mean SFCT increased with age from 288μm at 7 years of age to 304μm at 11 years, and then decreased to 258 μm at 18 years. In multivariate analysis, thicker SFCT was associated (regression coefficient r:0.38) with higher hyperopic refractive error (P<0.001;standardized regression coefficient beta:0.31;non-standardized regression coefficient B:7.61;95% confidence intervals (CI):6.29,8.93), younger age (P<0.001;beta:-0.10;B:-1.39;95%CI:-2.14,-0.64), male gender (P = 0.03;beta:-0.05;B:-5.33;95%CI:-10.1,-0.53), higher corneal refractive power (P<0.001;beta:0.12;B:3.68;95%CI:2.12,5.24), and non-Han Chinese ethnicity (P = 0.03;beta:0.05;B:6.16;95%CI:0.50,11.8). Ratio of CT(1000μm nasal to fovea)/SFCT (0.90±0.06;range:0.66,1.23) and ratio of CT(2500μm nasal to fovea)/SFCT (0.70±0.13;range:0.28,1.23) decreased with older age (P = 0.01;and P = 0.001, respectively), while ratio of CT(1000μm temporal to fovea)/SFCT (1.02±0.06;range:0.56,1.37) and ratio of CT(2500μm temporal to fovea)/SFCT (0.99±0.11;range:0.54,1.84) increased with older age (both P<0.001). Time spent outdoors or indoors was not significantly associated with CT-related parameter in multivariate analysis.

Conclusions

In contrast to SFCT in adults and despite elongating axial length, SFCT in children increased in cross-sectional analysis with older age (up to 11 years of age) and then started to decrease with further ageing. It suggests an increase in choroidal volume up to the age of 11 years. In children, the choroid was thickest at 1000μm temporal to the fovea, followed by the subfoveal region, and this difference significantly increased with older age. In contrast, CT nasal to the fovea in relationship to SFCT decreased with older age. CT was independent of lifestyle-associated parameters.