Changes in choroidal thickness and optical axial length accompanying intraocular pressure increase

Response of the human choroid to short-term changes in eyelid and periocular temperature

CLINICAL RELEVANCE

Choroidal thickness measurement is gaining popularity in clinical practice and research as an early indicator of myopia progression. Understanding the influence of temperature on choroidal thickness changes will improve the reliability of the measures.

BACKGROUND

It has been suggested that environmental temperature may affect choroidal thickness and blood flow, with potential implications for ocular disease and refractive development. This study investigates the effect of changes in eyelid/ocular adnexa temperature on choroidal thickness.

METHODS

In a paired-eye study, 20 young, healthy subjects received a warm stimulus (heat pack) over one closed eye and simultaneously a cold stimulus (ice pack) over the other for 10 min. Eyelid temperatures were monitored with thermal probes, and optical coherence tomography scans of the retina and choroid were taken before and after heating and cooling, and then every 5 min during a 15-min recovery period. Retinal and choroidal thicknesses were measured across the macular region (6 mm), including the subfoveal (1 mm), parafoveal (1-3 mm), and perifoveal (3-5 mm) regions, and compared between the cooled and warmed eyes.

RESULTS

When the thermal stimuli were applied, eyelid surface temperatures changed predictably and remained significantly different (by approximately 10-15°C) between the eyes after 2 min (p < .001). Relative to the warmed eye, macular choroidal thickness in the cooled eye increased significantly after 10 min of treatment (p = .004). This choroidal thickening response occurred in the subfoveal, parafoveal, and perifoveal regions (all p < .05). Upon removal of the thermal stimuli, choroidal thickness rapidly returned to the baseline and was no longer different between the cooled and warmed eye (p = .641).

CONCLUSION

Cooling the anterior eye by application of a cold stimulus directly onto the closed eyelid caused a small but significant increase in choroidal thickness relative to warming the anterior eye, demonstrating that the choroid can modulate its thickness rapidly and transiently in response to local temperature changes.

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.

[Biomechanics of the lamina cribrosa: A determining factor in glaucomatous neuropathy. A review of the literature]

Glaucoma is a chronic optic neuropathy characterized by progressive sclero-laminar remodeling. The main factor at the origin of these deformations is the intraocular pressure (IOP), the effect of which varies according to the biomechanical properties of the individual lamina cribrosa (LC). In this environment, the LC represents a malleable zone of weakness within a rigid corneoscleral shell. It is a dynamic structure whose movements play a key role in the pathogenesis of glaucoma: displacing it posteriorly, in addition to contributing to the characteristic appearance of glaucomatous cupping, would increase constriction on the nerve fibers and the laminar capillaries. Often incorrectly considered permanent in adults, these deformations have a certain degree of reversibility, which is currently better characterized thanks to progress in imaging techniques. The occurrence of anterior displacement and laminar thickening following a reduction in IOP could thus constitute a good prognostic factor by reducing mechanical stress on this region. These changes would tend to reduce laminar pore tortuosity and shear forces, which are probably key mechanisms of axonal loss in glaucoma.

Alterations in choroidal vascular structures due to serum levels of vascular endothelial growth factor in patients with POEMS syndrome

A higher serum vascular endothelial growth factor (VEGF) level can cause choroidal thickening in the choroid of patients with polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes (POEMS) syndrome. We aimed to determine whether fluctuations in serum VEGF levels affect choroidal vascular structures in patients with POEMS syndrome. This retrospective observational case series examined 17 left eyes of 17 patients with POEMS syndrome. Enhanced depth imaging optical coherence tomography (EDI-OCT) images were obtained, and serum VEGF levels were measured at baseline and 6 months after transplantation with dexamethasone (n = 6), thalidomide (n = 8), or lenalidomide (n = 3). EDI-OCT images were binarized using ImageJ software, and we calculated the areas of the whole choroid and the luminal and stromal areas. Subsequently, we determined whether the choroidal vascular structure had changed significantly between baseline and 6 months after treatment. Six months after treatment, serum VEGF levels and the whole choroid, luminal, and stromal areas had decreased significantly compared to the baseline values (all, P < 0.001). The mean luminal area to the whole choroidal area ratio at 6 months after treatment was 0.70 ± 0.03, which was significantly smaller than the ratio at baseline (0.72 ± 0.03; P < 0.001). Whole choroid and luminal area fluctuations were significantly positively correlated with fluctuations in serum VEGF levels (r = 0.626, P = 0.007 and r = 0.585, P = 0.014, respectively). Choroidal thickening induced by VEGF might be caused by increases in the choroidal vessel lumen area. These results may offer insights into the pathogenesis of POEMS syndrome and the role of serum VEGF in choroidal vascular structure, which may apply to other ocular diseases.

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 Effect of the Water Drinking Test on Ocular Parameters and Choroidal Thickness in Glaucoma Suspects

Background and objectives: We aimed to evaluate the effects of the water drinking test (WDT) on several systemic and ocular parameters, including choroidal thickness, which was assessed through optical coherence tomography angiography (OCTA), in glaucoma suspects. Materials and Methods: A total of 40 eyes from 20 glaucoma suspects without any systemic or ocular diseases were included in this prospective observational study. All the participants undertook the WDT, which required the drinking of 1 L of table water in 5 min. The outcome measures included IOP, systolic and diastolic blood pressure (SBP and DBP), mean arterial pressure (MAP), mean ocular perfusion pressure (MOPP), ocular pulse amplitude (OPA), and subfoveal and peripapillary choroidal thickness, which were assessed at baseline and at four 15 min intervals after the WDT. Generalized least squares models and mixed model analyses that take into account repeated measurements were used to assess the changes over time of these parameters. Results: All the ocular and systemic parameters showed statistically significant changes at all time points compared to baseline apart from choroidal thickness. The peak changes were an IOP of 20.1 mmHg versus 17.3 mmHg at 45 min, an SBP of 137.6 mmHg versus 125 mmHg at 30 min, a DBP of 95.9 mmHg versus 85.7 mmHg at 15 min, and an MOP of 53.51 mmHg versus 48.89 mmHg at 15 min. Conclusions: Despite elevations in IOP and significant changes in all the assessed systemic parameters, the WDT was not associated with changes in choroidal thickness in glaucoma suspects.

Optical coherence tomography findings in three patients with Werner syndrome

Background

Werner syndrome is a rare, autosomal recessive disorder characterised by premature aging. It is a typical hereditary progeroid syndrome that can be difficult to diagnose owing to its rarity and the similarity of some of its symptoms, such as juvenile cataracts, to other common ophthalmologic conditions. Early onset of bilateral cataracts is currently used as the ophthalmological feature for Werner syndrome; however, ophthalmologists often find performing a detailed examination of the medical history and genetic testing for Werner syndrome at the time of an ophthalmologic consultation challenging. If a unique ocular finding was observed on ocular examinations in cases of juvenile bilateral cataracts, we could consider Werner syndrome as a differential diagnosis. 

Case presentation

We documented the cases of three patients with Werner syndrome in whom thinning of the retina in the retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) were observed using optical coherence tomography (OCT). Visual field tests revealed the loss of visual field mainly owing to glaucoma.

The thinnig of the choroidal thickness (CT) in three patients was also observed using enhanced depth imaging (EDI)-OCT.

Conclusions

Three patients have thinning of the RNFL, GCC, and choroidal thickness and the loss of visual field. These findings suggest the need for including Werner syndrome in the differential diagnosis when patients presenting with juvenile cataracts of unknown cause also show abnormal retinal and choroidal thinning in the OCT images.

Acute effects of postural changes and lower body positive and negative pressure on the eye

Introduction: Entry into weightlessness results in a fluid shift and a loss of hydrostatic gradients. These factors are believed to affect the eye and contribute to the ocular changes that occur in space. We measured eye parameters during fluid shifts produced by lower body negative pressure (LBNP) and lower body positive pressure (LBPP) and changes in hydrostatic gradient direction (supine-prone) in normal subjects to assess the relative effects of fluid shifts and hydrostatic gradient changes on the eye.

Methods: Ocular parameters (intraocular pressure (IOP), ocular geometry, and optical coherence tomography measures) were measured in the seated, supine, and prone positions. To create a fluid shift in the supine and prone positions, the lower body chamber pressure ranged from -40 mmHg to +40 mmHg. Subjects maintained each posture and LBNP/LBPP combination for 15 min prior to data collection. A linear mixed-effects model was used to determine the effects of fluid shifts (as reflected by LBNP/LBPP) and hydrostatic gradient changes (as reflected by the change from seated to supine and from seated to prone) on eye parameters.

Results: Chamber pressure was positively correlated with both increased choroidal thickness (β = 0.11 ,p = 0.01) and IOP (β = 0.06 p < 0.001). The change in posture increased IOP compared to seated IOP (supine β = 2.1, p = 0.01, prone β = 9.5, p < 0.001 prone) but not choroidal thickness. IOP changes correlated with axial length (R = 0.72, p < 0.001).

Discussion: The effects of hydrostatic gradients and fluids shifts on the eye were investigated by inducing a fluid shift in both the supine and prone postures. Both hydrostatic gradients (posture) and fluid shifts (chamber pressure) affected IOP, but only hydrostatic gradients affected axial length and aqueous depth. Changes in choroidal thickness were only significant for the fluid shifts. Changes in hydrostatic gradients can produce significant changes in both IOP and axial length. Fluid shifts are often cited as important factors in the pathophysiology of SANS, but the local loss of hydrostatic gradients in the head may also play an important role in these ocular findings.

Elevated IOP Alters the Material Properties of Sclera and Lamina Cribrosa in Monkeys

Objective

Elevated intraocular pressure (IOP) has significant impacts on different stages in the progression of chronic glaucoma. In this study, we investigated changes in the material properties of sclera and lamina cribrosa (LC) in a nonhuman primate model with elevated IOP.

Methods

Normal adult Tibetan macaques were selected for the construction of elevated IOP model. After 40 days of stable maintenance on the ocular hypertension, the binocular eyeballs were obtained for the measurement of macroscopic parameters of the eyeballs. Posterior scleral tissue strips were obtained in circumferential and axial directions, and thickness was measured, respectively. Biomechanical parameters were obtained with stress relaxation, creep, and tensile test. The nanoindentation test was performed on the LC and scleral tissue around optic nerve head (ONH) to obtain compressive modulus.

Results

In the presence of elevated IOP, variations of the axial diameter of the eyeball were greater than those of the transverse diameter, and the mean scleral thickness around ONH was smaller in the experimental group than control group. The elastic modulus and stress relaxation modulus of sclera were larger, and the creep rate was lower in the experimental group than control group. In the control group, the elastic modulus and stress relaxation modulus of the circumferential sclera were larger in the axial direction, and creep rate was smaller. In the experimental group, there was no significant difference in biomechanical characteristics between the two directions. Compared to the control group, the compression modulus of the LC was smaller, and the compression modulus of sclera around ONH was larger in the experimental group.

Conclusion

Elevated IOP alters the viscoelasticity and anisotropy of sclera and LC. These may contribute to reduction of the organizational resistance to external forces and decline in the ability of self-recovery.

Classifications of Qualitative Characteristics on Angle Configurations via Ultrasound Biomicroscopy in Acute Primary Angle Closure

Purpose

To study the classifications of qualitative characteristics on the angle configurations in the acute primary angle closure (APAC) and fellow eyes by ultrasound biomicroscopy (UBM).

Methods

A total of 131 patients (262 eyes) were researched retrospectively. The qualitative parameters from UBM images were classified into iris form (IF), ciliary body configuration (CBC), basal iris thickness (BIT), iris convexity (IC), iris insert (II), iris angulation (IA), ciliary body size (CBS) and ciliary body position (CBP). Comparative analyses between the APAC (case group) and fellow (control group) eyes were performed.

Results

There were significant differences in IF, CBC, IC, II, CBS, CBP between the case group and control group in all quadrants (P<0.001). The IA of the case group and control group presented significant difference in all quadrants (P=0.001). However, there was not a significant difference in BIT between the case group and control group in all quadrants (P=0.495). The case group had fewer parallelogram-like and mushroom-like and more cone-like and hook-like CBCs than the control group (P<0.001).

Conclusion

Multiple ciliary body configurations can influence the stability of the lens and the anatomic configuration of the anterior chamber angle indirectly. New qualitative classification system of UBM may be more intuitionistic and refined to reflect the angle configurations to help clinical practice.

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.

Daily generation of a footward fluid shift attenuates ocular changes associated with head-down tilt bed rest

Astronauts have presented with a constellation of visual changes referred to as spaceflight-associated neuro-ocular syndrome (SANS). However, neither have early markers of microgravity-induced optic remodeling been fully identified nor have countermeasures been developed. To identify early markers of SANS, we studied 10 subjects with optical coherence tomography and ultrasonography when upright and supine and again after 24 h of 6° head-down tilt (HDT) bed rest. Upon acute transition from the upright to the supine position, choroid area (2.24 ± 0.53 to 2.28 ± 0.52 mm², P = 0.001) and volume (9.51 ± 2.08 to 9.73 ± 2.08 mm³, P = 0.002) increased. After 24 h of HDT bed rest, subfoveal choroidal thickness (372 ± 93 to 381 ± 95 µm, P = 0.02), choroid area (2.25 ± 0.52 to 2.33 ± 0.54 mm², P = 0.08), and volume (9.64 ± 2.03 to 9.82 ± 2.08 mm³, P = 0.08) increased relative to the supine position. Subsequently, seven subjects spent 3 days in -6°HDT bed rest to assess whether low-level lower body negative pressure (LBNP) could prevent the observed choroidal engorgement during bed rest. Maintaining the -6° HDT position for 3 days caused choroid area (Δ0.11 mm², P = 0.05) and volume (Δ0.45 mm³, P = 0.003) to increase. When participants also spent 8 h daily under -20 mmHg LBNP, choroid volume still increased, but substantially (40%) less than in the control trial (Δ0.27 mm³, P = 0.05). Moreover, the increase in choroid area was diminished (Δ0.03 mm², P = 0.13), indicating that low-level LBNP attenuates the choroid expansion associated with 3 days of -6° HDT bed rest. These data suggest that low-level LBNP may be an effective countermeasure for SANS.NEW & NOTEWORTHY Choroid measurements appear to be sensitive to changes in gravitational gradients, as well as periods of head-down tilt (HDT) bed rest, suggesting that they are potential indicators of early ocular remodeling and could serve to evaluate the efficacy of countermeasures for SANS. Eight hours of lower body negative pressure (LBNP) daily attenuates the choroid expansion associated with 3 days of strict -6° HDT bed rest, indicating that LBNP may be an effective countermeasure for SANS.

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.

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.

Difference of uveal parameters between the acute primary angle closure eyes and the fellow eyes

Purpose

To measure the anterior and posterior ocular biometric characteristics concurrently and to explore the relationship between iris, ciliary body and choroid in acute primary angle closure eyes (APAC) and fellow eyes.

Methods

It is a prospective, cross-sectional study. Thirty patients with recent APAC were finally enroled in it. Anterior and posterior uveal parameters were measured simultaneously by anterior segment optical coherence tomography (AS-OCT), swept-source optical coherence tomography (SS-OCT) and ultrasound biomicroscopy (UBM). The parameters were measured including: pupil diameter (PD); iris thickness, curvature (ICURV), area (IAREA); anterior chamber depth (ACD), width (ACW), area (ACA), volume (ACV); lens vault (LV); choroidal thickness and retinal thickness; maximum ciliary body thickness (CBTmax); ciliary body thickness at the point of the scleral spur (CBT0) and 1000 mm away (CBT1000); anterior placement of the ciliary body (APCB); and trabecular-ciliary angle (TCA).

Results

Compared with fellow eyes, APAC eyes had narrower anterior biometric parameters and presented with smaller anterior segment parameters (including ACD and ACW); (p < 0.01)), smaller IAREA and ICURV (p < 0.001), larger LV (p = 0.035), thinner ciliary body and less anterior ciliary process (p < 0.01). After adjustment for potential confounders (axial length, spherical equivalent and PD), APCB was positive correlated with choroidal thickness and CBT, and CBT was positive correlated with choroidal thickness.

Conclusions

Compared with fellow eyes, APAC eyes had narrower anterior biometric parameters, thinner ciliary body and smaller iris area and curvature. APCB, CBT and choroidal thickness were positively correlated. However, further studies are required before these conclusions are generalised.

Is There Any Role for the Choroid in Glaucoma?

The choroid is part of the uveal tract and is a heavily vascularized bed that also contains connective tissue and melanin pigment. Given the role of the choroidal vasculature in the blood supply of the anterior laminar and prelaminar regions of the optic nerve head, the peripapillary choroid might be a relevant target for investigation in patients with glaucoma. The purpose of this paper is to critically review the current understanding of potential role of the choroid in the pathogenesis of glaucomatous damage.

Diurnal macular choroidal area fluctuation in normal and primary open angle glaucoma groups

AIM

To assess and compare the diurnal macular choroidal area fluctuation in normal and primary open angle glaucoma (POAG) groups using enhanced depth imaging optical coherence tomography (EDI-OCT).

METHODS

Twenty-eight normal and 27 POAG eyes were enrolled in this study. EDI-OCT was used to measure the macular choroidal area every 3h from 9:00 a.m. to 21:00 p.m.

RESULTS

Significant diurnal fluctuations of macular choroidal area were observed in both normal (P=0.003) and POAG groups (P<0.001). But no significant macular choroidal area difference has been found between the two groups at all the five measurement time-points (512778±166242 vs 455079±207278 µm², P=0.195 at 9:00 a.m.; 501526±168953 vs 447846±211147 µm², P=0.245 at 12:00 a.m.; 501982±173158 vs 448024±206653 µm², P=0.239 at 15:00 p.m.; 508912±174589 vs 457783±207081 µm², P=0.252 at 18:00 p.m.; 503787±171241 vs 453230±205955 µm², P=0.274 at 21:00 p.m.; respectively). Furthermore, neither the fluctuation manners nor the change in macular choroidal area between the two adjacent measurement time points showed significant difference between normal and POAG groups (all P>0.05). In the meantime, significant diurnal intraocular pressure fluctuations were also observed in normal and POAG groups (both P<0.001).

CONCLUSION

In diurnal time, the macular choroidal area in both normal and POAG groups fluctuated significantly; moreover, neither the value of macular choroidal area, nor the fluctuation of macular choroidal area in POAG group is significantly different from that in normal group.

Intraocular Pressure, Axial Length, and Refractive Changes after Phacoemulsification and Trabeculectomy for Open-Angle Glaucoma

PURPOSE

To compare changes in intraocular pressure (IOP), axial eye length (AEL), and refractive outcome in primary open-angle glaucoma patients undergoing cataract surgery and trabeculectomy in dependence of the sequence of surgeries.

MATERIALS AND METHODS

We retrospectively analysed 48 eyes. The changes in refraction, intraocular pressure, and axial eye length were analysed after surgery. In group A (21 subjects), phacoemulsification was performed before trabeculectomy, and in group B (27 subjects), trabeculectomy was performed before phacoemulsification with a minimum time span between interventions of 6 months.

RESULTS

The reduction in IOP and the decrease in AEL after trabeculectomy were significant after 6 and 12 months postsurgery (p < 0.001 each). The decrease in AEL was 0.42 ± 0.11% at 6 months after surgery and 0.40 ± 0.13% after 12 months from surgery; this decrease in AEL was comparable between the groups. The refractive outcome was significantly different between the groups (group A: 0.35 ± 0.75 dpt, group B: -0.05 ± 0.36 dpt, p = 0.018); in group A, trabeculectomy caused a hyperopic shift of 0.34 ± 0.44 dpt (p = 0.002) at 12 months postsurgery.

CONCLUSION

IOP reduction after trabeculectomy causes AEL shortening. The effect on refractive outcome depends on the sequence of surgeries. Better refractive outcome is achieved if phacoemulsification is performed after trabeculectomy.

Longitudinal change in choroidal thickness after trabeculectomy in primary open-angle glaucoma patients

PURPOSE

To investigate longitudinal changes in intraocular pressure (IOP), axial length (AL), and choroidal thickness (ChT) in primary open-angle glaucoma (POAG) eyes after trabeculectomy and to evaluate the parameters that might influence those changes.

METHODS

In this prospective observational study, we recruited 28 patients with POAG (28 eyes) scheduled for trabeculectomy. The average macular ChTs and foveal retinal thicknesses along 6-mm segments centered on the fovea were examined preoperatively and postoperatively (at 1, 3, and 6 months) using swept-source optical coherence tomography. The IOP, AL, and mean deviation (MD) of standard automated perimetry (SAP) were also analyzed as independent variables.

RESULTS

Results from 16 patients were included in the final analysis. A significant increase in ChT with respect to the preoperative value was observed at every postoperative stage (1 month, P < 0.001; 3 months, P < 0.001; 6 months, P = 0.011), whereas the retinal thickness showed no significant change over the study period. The ChT increase and IOP reduction were sustained throughout the 6-month period without further significant changes. Stepwise multivariate analyses showed significant correlations between the percentage decrease in IOP and the percentage increase in ChT at 1 and 6 months postoperatively. The percentage increase in ChT was also significantly correlated with a better MD of the SAP at 1 month (β = 0.01; P = 0.009).

CONCLUSIONS

The ChT increase following trabeculectomy was sustained at 1, 3, and 6 months postoperatively. The percentage increase in ChT was significantly correlated with the percentage change in IOP and (more weakly) with better SAP MD values.

Changes in subfoveal choroidal thickness and reduction of serum levels of vascular endothelial growth factor in patients with POEMS syndrome

AIMS

To determine the changes in the subfoveal choroidal thickness (CT), the foveal thickness (FT) and the serum level of vascular endothelial growth factor (VEGF) after thalidomide treatment in patients with polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy and skin changes (POEMS) syndrome.

METHODS

We studied 13 left eyes of 13 treatment-naïve patients with POEMS syndrome. The subfoveal CT and FT were determined by enhanced depth imaging optical coherence tomography, and the serum level of VEGF was determined by ELISA at the baseline and at 6 months after thalidomide treatment. The correlations in the serum level of VEGF and the subfoveal CT or the FT at the baseline and at 6 months after treatment were determined.

RESULTS

Together with the reduction in the serum level of VEGF, the subfoveal CT was also reduced significantly from 439.1±66.5 µm at the baseline to 307.2±75.4 µm at 6 months (p=0.001). The mean FT at the baseline was 236.4±30.7 µm which did not change significantly at 6 months at 228.1±33.1 µm (p>0.05). The change in the subfoveal CT was significantly and linearly correlated with the change in the serum level of VEGF at 6 months after treatment (r=0.67, p=0.011).

CONCLUSIONS

The significant correlation between the CT and the serum level of VEGF may offer clues on the pathogenesis of ocular diseases of POEMS syndrome and on the role of serum VEGF on the choroid.

Changes in Axial Length and Refractive Error After Noninvasive Normalization of Intraocular Pressure From Elevated Levels

PURPOSE

To explore the changes in axial length and refractive error after noninvasive normalization of intraocular pressure (IOP) from elevated levels.

DESIGN

A prospective observational study.

METHODS

We enrolled 51 consecutive patients with abnormally elevated unilateral IOP (≥10 mm Hg compared with that of the fellow eye, in which the IOP was ≤21 mm Hg). In all patients, the keratometric value and axial length were obtained with the aid of an IOLMaster before and after IOP normalization (defined as attainment of an IOP difference of ≤3 mm Hg compared with the fellow eye, with or without topical application of ocular hypotensive therapy). We focused principally on IOP, axial length, the keratometric value, and the predicted refractive difference (the predicted refractive error after IOP normalization upon placement of an IOL with a power for emmetropia correction determined prior to IOP normalization).

RESULTS

The axial length was significantly reduced from 23.5 to 23.3 mm after IOP normalization, from 45.9 mm Hg to 14.3 mm Hg (P < .001). The change in IOP correlated with that of the axial length (r = 0.826, P < .001), but not with the change in the keratometric value (P = .618). The change in axial length per 10 mm Hg IOP decrease was -0.06 mm (P < .001). The IOP change was correlated with the predicted refractive difference (r = 0.693, P < .001); the predicted refractive difference per 10 mm Hg IOP decrease was +0.15 diopter (P < .001).

CONCLUSIONS

The axial length decreased and the predicted refractive difference increased (hyperopia) as IOP decreased. Therefore, a possible risk of postoperative hyperopic shift should be considered when biometric examination for IOL power calculation is performed in a patient with an abnormally elevated IOP.

Choroidal thickness using EDI-OCT in adult-onset vitelliform macular dystrophy

BACKGROUND

To compare choroidal thickness in patients with adult-onset foveomacular vitelliform dystrophy (AOFVD) with healthy subjects and to correlate choroidal thickness with age, gender and spherical equivalent.

METHODS

A prospective, observational study of 37 eyes (15 eyes in AOFVD group and 22 eyes in control group) was conducted. Images were acquired by enhanced depth imaging optical coherence tomography (EDI-OCT). Choroidal thickness measurements were performed in the subfoveal region and at 500, 1000 and 1500 µm intervals from the foveal center to nasal and to temporal regions for subsequent averaging of values.

RESULTS

The AOFVD group consisted of four male eyes (28.6 %) and 10 female eyes (71.4 %); age was 33-62 years; spherical equivalent (SE) ranged from -1.50 to 1.50 spherical diopters (SD); mean subfoveal thickness was 325.6 µm, ranging from 186 to 420 µm; and the average of thicknesses was 309.4 µm, ranging from 188 to 413 µm. The control group consisted of 12 male eyes (54.5 %) and 10 female eyes (45.5 %); age was 27-62 years; SE ranged from -2.50 to 0.50 SD; subfoveal thickness was 294.8 µm, ranging from 213 to 481 µm; and the average of thicknesses was 279.4 µm, ranging from 201 to 458 µm.

CONCLUSIONS

The AOFVD group and the control group showed similar choroidal thickness by correcting for age, SE and gender. Not yet known, completely, which biochemical and vascular flow alterations of the choroid, and which functional RPE changes may play a role in the pathogenesis of this disease. EDI-OCT, incorporated in some SD-OCT devices, allows higher quality assessment of the choroid. In this article, choroidal thickness of patients with AOFVD, a rare disease with a not fully understood pathogenesis, was assessed.

Choroidal Thickness in Open-angle Glaucoma

PURPOSE

To examine choroidal thickness in open-angle glaucoma.

METHODS

The hospital-based case series study included a study group with patients with open-angle glaucoma and a control group. Choroidal thickness was measured by enhanced depth imaging by spectral domain optical coherence tomography.

RESULTS

The study group included 39 patients (71 eyes) and the control group consisted of 189 patients (228 eyes) with no significant difference between both groups in age (P=0.16) and refractive error (P=0.07). Choroidal thickness in the foveal region (P=0.18), at a distance of 1000 μm from the fovea (P=0.39), 2000 μm from the fovea (P=0.46), and 2500 μm from the fovea (P=0.53) did not vary significantly between both groups. In multivariable analysis with adjustment for age and refractive error, choroidal thickness at the fovea [P=0.12; regression coefficient B: minus-8.60; 95% confidence interval (CI): -19.3, 2.1], at a horizontal distance of 1000 μm from the fovea (P=0.30; regression coefficient B: -4.98; 95% CI: -14.3, 4.4), 2000 μm from the fovea (P=0.20; regression coefficient B: -20.9; 95% CI: -53.2, 11.3), and 2500 μm from the fovea (P=0.45; regression coefficient B: -2.70; 95% CI: -9.67, 4.27) was not significantly associated with the diagnosis of glaucoma. In binary regression analysis with adjustment for age and refractive error, presence of glaucoma was significantly associated neither with subfoveal choroidal thickness [P=0.12; odds ratio (OR): 0.997; 95% CI: 0.993, 1.001] nor with choroidal thickness at a horizontal distance of 1000 μm from the fovea (P=0.47; OR: 0.998; 95% CI: 0.993, 1.002), 2000 μm from the fovea (P=0.23; OR: 0.997; 95% CI: 0.993, 1.002), or 2500 μm from the fovea (P=0.46; OR: 0.998; 95% CI: 0.992, 1.004).

CONCLUSIONS

After adjusting for age and refractive error, open-angle glaucoma was not significantly associated with a marked thinning or a thickening of the choroid in the foveal and parafoveal region.

Enhanced depth imaging-optical coherence tomography of the choroid in moderate and severe primary angle-closure glaucoma

PURPOSE

To compare the choroidal thickness (CT) in eyes with moderate and severe primary angle-closure glaucoma (PACG) with the eyes of healthy controls.

METHODS

Fifty-nine patients (59 eyes) with PACG and 56 age-matched normal subjects underwent macular CT scanning using enhanced depth imaging-optical coherence tomography. The subjects with PACG were further classified as having moderate [-12 dB ≤ visual field mean deviation (VF-MD) ≤ -6 dB] or severe (VF-MD < -12 dB) glaucoma. The average CT of the PACG eyes at each location was compared to that of normal eyes.

RESULTS

The CT was significantly increased in moderate and severe PACG eyes compared with the normal eyes at all nine macular locations, with the exception of 1 and 3 mm superior to the fovea. The mean CT under the fovea was 292.0 ± 48.2 μm in the moderate PACG eyes, 277.1 ± 58.3 μm in the severe PACG eyes and 249.9 ± 72.1 μm in the normal eyes, respectively. There were no significant differences between the macular CTs in the eyes with moderate PACG and those in severe PACG eyes (all p > 0.05). Factors associated with a thinner choroid were ageing (p < 0.001), female (p = 0.036) and increasing axial length (p = 0.021). Neither the VF-MD nor pattern standard deviation was found to be associated with CT.

CONCLUSIONS

The CT is greater in patients with PACG, but it does not differ between moderate and severe PACG, suggesting a lack of relationship between CT and the progression of glaucoma based on EDI-OCT measurements.

Effects of Valsalva Maneuver on Ocular Biometric Parameters: Optical Low-Coherence Reflectometry Biometer Study

PURPOSE

To evaluate the effects of the Valsalva Maneuver (VM) on ocular biometry and intraocular pressure (IOP).

METHODS

This prospective observational study included 55 eyes of 55 healthy volunteers. Axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), corneal curvature (K-steep, K-flat and K-mean), corneal diameter (WtW), and pupil diameter (PD) were measured with a LenStar LS 900® biometer at rest and during VM. The IOP was also measured at rest and during VM measurements were compared.

RESULTS

The VM did not have any significant influence on AL, WtW, K-flat, and K-mean (p > 0.05), but it decreased K-steep significantly (p < 0.001). Moreover, CCT and ACD decreased significantly during VM (p < 0.001), but VM increased IOP, PD (p < 0.001), and LT significantly (p = 0.002).

CONCLUSIONS

The VM might reversibly change in IOP and ocular biometry, so it should be considered during anterior segment examinations.

Correlation between serum level of vascular endothelial growth factor and subfoveal choroidal thickness in patients with POEMS syndrome

PURPOSE

The study was conducted to determine whether serum vascular endothelial growth factor (VEGF) levels are significantly correlated with subfoveal choroidal thickness (CT) and foveal thickness (FT) in patients with polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes (POEMS) syndrome.

PATIENTS AND METHODS

In this cross-sectional observational case series, we studied 31 eyes of 16 treatment-naïve patients with POEMS syndrome with no evidence of fundus abnormalities. Subfoveal CT and FT were measured using enhanced depth imaging optical coherence tomography (EDI-OCT), and correlations between serum VEGF levels and subfoveal CT and FT were determined.

RESULTS

The mean subfoveal CT was 417.9 ± 73.5 μm (right eye, 416.7 ± 81.2 μm; left eye, 419.0 ± 68.1 μm), and the mean FT was 243.8 ± 35.2 μm (right eye, 248.8 ± 22.0 μm; left eye, 239.1 ± 44.6 μm). There was a significant positive correlation between the serum VEGF level and subfoveal CT (right eye, r = 0.58, p = 0.021; left eye, r = 0.60, p = 0.012), but the correlation between the level of serum VEGF and FT was not significant (right eye, r = 0.007, p > 0.05; left eye, r = 0.25, p > 0.05).

CONCLUSIONS

The significant correlation between the serum VEGF level and subfoveal CT in patients with POEMS syndrome suggests that choroidal thickness is influenced by the level of serum VEGF. These results not only aid in an understanding of the pathogenesis of ocular changes in patients with POEMS syndrome, but also offer clues regarding the pathogenesis of other choroidal diseases.

Assessment of choroidal thickness in healthy and glaucomatous eyes using swept source optical coherence tomography

Purpose

To evaluate choroidal thickness (CT) in healthy and glaucomatous eyes using Swept Source Optical Coherence Tomography (SS-OCT).

Methods

A cross-sectional observational study of 216 eyes of 140 subjects with glaucoma and 106 eyes of 67 healthy subjects enrolled in the Diagnostic Innovations in Glaucoma Study. CT was assessed from wide-field (12×9 mm) SS-OCT scans. The association between CT and potential confounding variables including age, gender, axial length, intraocular pressure, central corneal thickness and ocular perfusion pressure was examined using univariable and multivariable regression analyses.

Results

Overall CT was thinner in glaucomatous eyes with a mean (± standard deviation) of 157.7±48.5 µm in glaucoma compared to 179.9±36.1 µm in healthy eyes (P<0.001). The choroid was thinner in both the peripapillary and macular regions in glaucoma compared to controls. Mean peripapillary CT was 154.1±44.1 µm and 134.0±56.9 µm (P<0.001) and macular CT 199.3±46.1 µm and 176.2±57.5 µm (P<0.001) for healthy and glaucomatous eyes respectively. However, older age (P<0.001) and longer axial length (P<0.001) were also associated with thinner choroid and when differences in age and axial length between glaucomatous and healthy subjects were accounted for, glaucoma was not significantly associated with CT. There was also no association between glaucoma severity and CT.

Conclusions

Glaucoma was not associated with CT measured using SS-OCT; however, older age and longer axial length were associated with thinner choroid so should be considered when interpreting CT measurements.

Change in choroidal thickness and axial length with change in intraocular pressure after trabeculectomy

BACKGROUND/AIMS

We studied the change in choroidal thickness (CT) and axial length (AL) after intraocular (IOP) changes produced by trabeculectomy.

METHODS

Twenty-one eyes of 20 patients were studied preoperatively, and then postoperatively at 1 week, 1, 3, and 6 months. Variables measured included IOP, AL, keratometry, refractive error, central corneal thickness, and average CT in the posterior 6 mm centred on the fovea using enhanced depth imaging spectral domain optical coherence tomography (OCT).

RESULTS

OCT images in 17 eyes (58 images, preoperatively and postoperatively) were of sufficient quality to determine CT. In every patient, CT increased with IOP lowering postoperatively. For each 1 mmHg decrease in IOP, there was a mean increase of 3.4 µm in CT (p<0.0001; univariate regression, 95% CI 2.5 to 4.3). This represented a CT increase of 1.7% per mm Hg decrease (p<0.0001; 95% CI 1.3 to 2.0%). AL decreased by 6.8 µm per mm Hg decrease in IOP (p<0.0001, univariate regression, 95% CI 4.9 to 8.6).

CONCLUSIONS

The dynamic relationship between change in IOP and the state of sclera and choroid was confirmed by sequential measurements in postoperative trabeculectomy patients, providing estimates of the magnitude of choroidal swelling and scleral volume decrease with IOP lowering.

Changes in choroidal thickness, axial length, and ocular perfusion pressure accompanying successful glaucoma filtration surgery

PURPOSE

To investigate the changes in choroidal thickness (CT), axial length (AL), and ocular perfusion pressure (OPP) accompanying intraocular pressure (IOP) reduction after trabeculectomy. methods: Thirty-nine eyes of 39 patients with primary open-angle glaucoma uncontrolled by medical therapy were included in this prospective and interventional study. All patients underwent a fornix-based trabeculectomy. The CT was measured by enhanced depth imaging-optical coherence tomography. IOP, AL, and systolic/diastolic blood pressure were also measured, and OPP was calculated. All measurements were performed at baseline and 1 month after surgery.

RESULTS

The mean IOP was 25.0 ± 5.8 mm Hg at baseline and 11.7 ± 2.6 mm Hg after trabeculectomy (P<0.001), and the mean subfoveal CT was 295 ± 84 mm Hg at baseline and 331 ± 82 mm Hg after trabeculectomy (P<0.001). The mean AL was 23.64 ± 0.98 mm at baseline and 23.54 ± 0.96 mm after trabeculectomy (P<0.001), whereas the mean OPP was 38.8 ± 6.2 mm Hg preoperatively, and 51.1 ± 7.3 mm Hg postoperatively (P<0.001). The change in CT negatively correlated with the change in IOP (r=-0.785, P<0.001) and AL (r=-0.693, P<0.001), whereas it positively correlated with the change in OPP (r=0.418, P=0.008).

CONCLUSION

These results suggest that the large IOP decrease following trabeculectomy causes choroidal thickening. In addition, CT changes are associated with IOP and AL reduction as well as OPP increase.