Changes in axial length and choroidal thickness after intraocular pressure reduction resulting from trabeculectomy

Effects of reduction in intraocular pressure after trabeculotomy on axial length and intraocular lens selection

PURPOSE

To investigate the relationship between intraocular pressure (IOP) and axial length (AL) and to compare the refractive predicted error in patients who have undergone cataract surgery alone or in combination with trabeculotomy.

SETTING

Hospital.

DESIGN

Single-center, retrospective, case-control.

METHODS

The medical records of patients who had undergone cataract surgery alone or in combination with trabeculotomy using the Tanito microhook were retrospectively reviewed. Patients were grouped into cataract surgery alone (CAT) or cataract surgery combined with trabeculotomy (LOT) groups. Demographic data, preoperative and postoperative IOP and AL, and surgically induced astigmatism (SIA) were analyzed before and 1 month postoperatively to evaluate the interplay between IOP, AL, and refractive outcomes.

RESULTS

52 eyes (52 patients) underwent LOT, and 67 eyes (67 patients) underwent CAT. The mean IOP at baseline did not differ between the groups; the change in IOP (dIOP) was significantly higher in the LOT group than in the CAT group. The mean AL at baseline and the change in AL (dAL) were 24.0 ± 1.2 mm and 0.16 ± 0.11 mm, respectively, in the LOT group, and 23.8 ± 1.1 mm and 0.11 ± 0.070 mm, respectively, in the CAT group. The difference in dAL was also significant. In the LOT group, dIOP and dAL were significantly correlated. The mean SIA vectors did not significantly differ between the groups.

CONCLUSIONS

AL decreased because of the reduction in IOP after cataract surgery combined with trabeculotomy. Consequently, the refractive target error was greater, and the postoperative refractive outcome showed a tendency toward hyperopia.

Reversal of severe myopia by 24 years of hypotony with subsequent stable refraction after 2 years of normal intraocular pressure

Purpose

To report sustained axial length shortening and hyperopic shift (refraction changed from -8 to -2 diopters) induced by 24 years of profound IOP (intraocular pressure) reduction with subsequent refractive stability 2 years after IOP rose to 11-17 mm Hg.

Observations

A 25-year-old woman with elevated episcleral venous pressure glaucoma underwent non-penetrating trabeculectomy and subsequent laser goniopuncture in her left eye. She had chronically low IOP (1-12 mm Hg) for the next 24 years. Hypotony maculopathy was present in postoperative years 13-14 and 18-24 but resolved at age 49 when emesis-induced iris prolapse obstructed the filtering passage and transiently raised IOP to 40. Medical management and iridectomy with flap suturing stabilized IOP between 11 and 17 mm Hg.Refraction before OS trabeculectomy was OD -7.50/OS -9.00. In postoperative year 24 spherical equivalent phakic refraction was OD -9.00/OS -1.50. Biometry 1 year after resolution of hypotony showed axial lengths OD 24.8, OS 22.6 mm. Cataract surgery was performed in postoperative years 24/26 (OD/OS) with Tecnis DCBOO intraocular lenses of powers 14.0/21.5 diopters; postoperative refractions, 2 years after OS IOP rose to 11-17 mm Hg, were OD +0.25-0.50 x 015/OS -0.75-1.25 x 160 with 20/25 corrected acuity in each eye.Cardiovascular symptoms 24 years after the onset of her glaucoma led to a diagnosis of severe pulmonary hypertension.

Conclusions and importance

This case demonstrates that 2 decades of chronic IOP reduction can reverse myopia (by > 2 mm reduction in axial length) with subsequent refractive stability 2 years after IOP normalization. In addition, the case shows that ocular signs of pulmonary hypertension may precede cardiovascular signs by 2 decades.

Early Postoperative Changes in Macular Choroidal Thickness After Uncomplicated Phacoemulsification in Patients With and Without Glaucoma: A Swept-Source Optical Coherence Tomography Study

Purpose The objective of this study was to examine the impact of uncomplicated phacoemulsification on macular choroidal thickness (CT) within the first three postoperative months and to investigate its relationship with postoperative cystoid macular edema (CME) in both glaucomatous and healthy subjects, utilizing swept-source optical coherence tomography (SS-OCT). Methods The non-randomized prospective study involved 82 patients, selected via convenience sampling from the First Department of Ophthalmology, Medical School of Athens, "G. Gennimatas" Hospital, Athens, Greece, between May 2018 and May 2022, undergoing phacoemulsification and intraocular lens (IOL) implantation. The inclusion criteria encompassed patients aged 50 years or above, with or without glaucoma. Patients with ocular pathologies that could influence macula or CT measurements were excluded. Data collection focused on retinal and CT variables of the macular area, measured using SS-OCT. Baseline measurements were established preoperatively, with follow-up assessments at one week, one month, and three months postoperatively to monitor CT and macular edema onset. Results A total of 82 eyes from 82 patients with a mean age of 79.1±8.3 years were included. The study population was divided into a glaucoma group (n=28 eyes) and a control group (n=54 eyes). Our findings indicate a consistently significant increase in macular CT measurements one month after cataract surgery, observed in both glaucomatous and non-glaucomatous eyes. In the first postoperative week, statistically significant changes in CT were observed only in patients with CME. Subsequently, at one-month interval, both patient groups, those with and without CME, exhibited statistically significant changes in CT across all macular sectors. CME was detected in 10 out of 28 eyes in the glaucoma group and in 16 out of 54 eyes in the control group. When evaluating the impact of postoperative CME on groups of glaucomatous and non-glaucomatous eyes, it was observed that glaucomatous eyes exhibited a significantly larger magnitude of change in subfoveal CT (SFCT) (p=0.03) at one month (relative to baseline) compared to non-glaucomatous eyes. There was also a 31% increase in the odds of developing CME for glaucoma patients; this result was not statistically significant (odds ratio {OR}, 1.31; 95% confidence interval {CI}, 0.50-3.47; p=0.57). Conclusions During the early postoperative period, the study revealed a significant increase in CT at one month after phacoemulsification in both glaucomatous and non-glaucomatous eyes. When CME was present, a significantly more pronounced magnitude of change in SFCT was observed at one month in glaucomatous eyes, as opposed to non-glaucomatous eyes. This observation suggests a possible selective susceptibility of glaucomatous eyes in the early postoperative period that requires further research.

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.

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.

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

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

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

Purpose

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

Methods

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

Results

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

Conclusions

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

Translational Relevance

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

Wide-Field Swept-Source OCT Analysis of Interocular Symmetry of Choroidal Thickness in Subjects with Uncomplicated Pachychoroid

BACKGROUND

We aimed to study the bilateral choroidal thickness (CT) symmetry and difference in uncomplicated pachychoroid subjects using wide-field swept-source optical coherence tomography (SS-OCT).

METHODS

All subjects underwent a wide-field 16-mm one-line scan using SS-OCT. Bilateral CT was measured at, and compared among, the following 12 points: three points at 900-µm intervals from the nasal optic disc margin (nasal peripapillary area), one point at the subfovea, six points at 900-µm intervals from the fovea to the nasal and temporal areas (macular area), and two peripheral points 5400 and 8100 µm from the fovea (peripheral area).

RESULTS

There were no statistically significant differences in CT between the right and left eyes in any area (all p > 0.05); they all showed significant positive correlations (all p < 0.01). However, the correlation coefficients (ρ) were smaller for the nasal peripapillary and peripheral areas compared to the macular area.

CONCLUSIONS

The CTs in each region were bilaterally symmetrical in subjects with uncomplicated pachychoroid. However, interocular difference in CT increased from the center to the periphery, indicating that the anatomical variation of the nasal peripapillary and peripheral choroid was greater than that of the macula.

Influence of Chronic Ocular Hypertension on Emmetropia: Refractive, Structural and Functional Study in Two Rat Models

Chronic ocular hypertension (OHT) influences on refraction in youth and causes glaucoma in adulthood. However, the origin of the responsible mechanism is unclear. This study analyzes the effect of mild-moderate chronic OHT on refraction and neuroretina (structure and function) in young-adult Long-Evans rats using optical coherence tomography and electroretinography over 24 weeks. Data from 260 eyes were retrospectively analyzed in two cohorts: an ocular normotension (ONT) cohort (<20 mmHg) and an OHT cohort (>20 mmHg), in which OHT was induced either by sclerosing the episcleral veins (ES group) or by injecting microspheres into the anterior chamber. A trend toward emmetropia was found in both cohorts over time, though it was more pronounced in the OHT cohort (p < 0.001), especially in the ES group (p = 0.001) and males. IOP and refraction were negatively correlated at week 24 (p = 0.010). The OHT cohort showed early thickening in outer retinal sectors (p < 0.050) and the retinal nerve fiber layer, which later thinned. Electroretinography demonstrated early supranormal amplitudes and faster latencies that later declined. Chronic OHT accelerates emmetropia in Long–Evans rat eyes towards slowly progressive myopia, with an initial increase in structure and function that reversed over time.

Wide-Field Swept-Source Optical Coherence Tomography Analysis of Interocular Symmetry of Choroidal Thickness in Healthy Young Individuals

Purpose

The purpose of this paper was to study the bilateral choroidal thickness (CT) symmetry and differences in healthy individuals using wide-field swept-source optical coherence tomography (SS-OCT).

Methods

All participants underwent a wide-field 16-mm 1-line scan using SS-OCT. CTs were measured at the following 12 points: 3 points at 900 µm, 1800 µm, and 2700 µm away from the nasal optic disc margin (nasal peripapillary area), 1 point at the subfovea, 6 points at 900 µm, 1800 µm, and 2700 µm away from the subfovea to the nasal and temporal areas (macular area), and 2 peripheral points at 2700 and 5400 µm from temporal point 3 (peripheral area). Bilateral CTs were measured; their correlations and differences in the corresponding regions were analyzed.

Results

There were no statistically significant differences in CTs between the right and left eyes in all corresponding areas (all P > 0.05); they all showed significant positive correlation coefficients (r) (all P < 0.001). However, the nasal peripapillary and peripheral areas had relatively low correlation coefficients, compared to the macular areas. In addition, the bilateral CT differences were 32.60 ± 25.80 µm in the macular area, 40.67 ± 30.58 µm in the nasal peripapillary area, and 56.03 ± 45.73 µm in the peripheral area (all P < 0.001).

Conclusions

Overall, the CTs of each region were bilaterally symmetrical. However, the differences in CTs increased from the center to the periphery, which indicated that the anatomic variation of the nasal peripapillary and peripheral choroid was greater than that of the macula.

Immediate Choroidal Expansion after Bleb Needling

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

Lamina Cribrosa Moves Anteriorly After Trabeculectomy in Myopic Eyes

Purpose

The purpose of this study was to investigate changes in lamina cribrosa (LC) depth after trabeculectomy in myopic eyes using enhanced depth imaging (EDI) spectral-domain optical coherence tomography (SD-OCT).

Methods

Serial horizontal B-scans of the optic nerve head of 41 myopic eyes with primary open-angle glaucoma (POAG) were obtained before and 3 months after trabeculectomy using EDI SD-OCT. LC depth, defined as the distance from the opening plane of Bruch's membrane to the level of the anterior LC surface, was measured before and 3 months after trabeculectomy at 7 locations spaced equidistantly across the vertical optic disc diameter on B-scan images. The mean of the measurements at these seven planes was defined as the average LC depth. Factors associated with changes in LC depth were identified by linear regression.

Results

Intraocular pressure (IOP) decreased from 26.3 ± 9.3 millimeters of mercury (mm Hg) preoperatively to 10.6 ± 3.5 mm Hg 3 months after trabeculectomy. LC depth was significantly lower 3 months after trabeculectomy than preoperatively (P < 0.001, all planes). The magnitude of LC depth reduction was significantly associated with younger age, higher preoperative LC depth, and greater magnitude of IOP reduction (all P ≤ 0.016).

Conclusions

LC depth reduction was observed after trabeculectomy in myopic eyes. The degree of LC depth reduction was not related to the degree of myopia.

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.

Does using topical latanoprost affect subfoveal choroidal thickness?

Purpose: The aim of our prospective study was to investigate the effect of using latanoprost eye drops on subfoveal choroidal thickness in the macular area, as measured by using enhanced depth imaging optical coherence tomography (EDI-OCT). Materials and methods: A total of 39 eyes from 39 patients with bilateral glaucoma or ocular hypertension who had never received hypotensive therapy (study group) and 39 eyes from 39 age- and gender-matched healthy individuals (control group) were included in this study. The EDI-OCT measurements of subfoveal choroidal thickness were obtained during an initial visit before latanoprost therapy and at visits after 1 and 3 months of latanoprost therapy. Results: The mean subfoveal choroidal thickness was 309.5 ± 38.5 µm before latanoprost therapy in the study group and 307.3 ± 31.8 µm in the control group (p = .794). During latanorprost therapy in the study group, mean values of subfoveal choroidal thickness at the initial visit and at intervals of 1 and 3 months were 309.5 ± 38.5 µm, 314.2 ± 39.7 µm, and 318.3 ± 33.4 µm, respectively, which indicated a statistically significant difference between the initial and third visits only (p=.002). Conclusion: Subfoveal choroidal thickness increased after 3 months of topical latanoprost therapy.

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

Purpose

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

Methods

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

Results

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

Conclusions

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

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

Background

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

Methods

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

Results

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

Conclusions

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

Changes in choroidal thickness following trabeculectomy and its correlation with the decline in intraocular pressure

PURPOSE

Evaluate whether there are significant changes in choroidal thickness following trabeculectomy, and how they relate do the decline in intraocular pressure.

METHODS

This was a prospective evaluation of 28 eyes who underwent Moorfields modified trabeculectomy. The choroidal thickness was measured via OCT with enhanced depth imaging, before surgery and 1 day, 1 week and 1 month after surgery. Measurements were taken at the fovea, 1000 µm temporal to the fovea and 1000 µm nasal to the fovea. The relationship between choroidal thickness and intraocular pressure was statistically evaluated.

RESULTS

The mean intraocular pressure before surgery was 25.07 ± 4.64 mmHg; 8.57 ± 3.62 mmHg after 1 day; 10.36 ± 4.39 mmHg after 1 week and 13.71 ± 5.13 mmHg after 1 month. Mean choroidal thickness increased after trabeculectomy with maximal values at 1 week. The largest increase was found at the fovea, with an average before surgery of 253.54 ± 62.01 µm; 286.75 ± 64.20 µm at 1 day, 286.36 ± 63.14 µm at 1 week and 271.00 ± 60.31 µm at 1 month. Increase in choroidal thickness was significant 1 day and 1 week after surgery in the foveal (p = 0.012, p = 0.007) and temporal (p = 0.040, p = 0.000) locations and 1 week postoperatively on the nasal location (p = 0.016). None of them were significant at 1 month after surgery. Preoperative IOP and choroidal thickness were correlated at all macular locations (ρ = 0.449-0.525, p = 0.004-0.016) yet no correlation was found between increase in choroidal thickness and decline in intraocular pressure in the postoperative period.

CONCLUSION

Choroidal thickness appears to increase temporarily after trabeculectomy and these changes were not correlated with the decline in intraocular pressure. Further research is required to fully understand this phenomenon.

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

PURPOSE:

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

METHODS:

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

RESULTS:

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

CONCLUSION:

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

Excessive scleral shrinkage, rather than choroidal thickening, is a major contributor to the development of hypotony maculopathy after trabeculectomy

Purpose

We previously reported that eyes with hypotony maculopathy (HM) after trabeculectomy (TLE) exhibited more reduction of axial length (AL) than those without HM, suggesting that inward collapse of the scleral wall may contribute to the development of HM after TLE. However, we did not evaluate change in choroidal thickness (CT), which could influence AL measures. We compared the magnitude and rate of AL and CT changes in eyes with and without HM by simultaneously measuring these parameters before and after TLE.

Methods

We enrolled 77 eyes of 77consecutive patients with glaucoma, who underwent TLE between March 2014 and March 2016. Intraocular pressure (IOP), central corneal thickness, keratometry, AL, and CT were measured pre- and postoperatively, up to 6 months. These biometrics were compared in eyes with and without HM.

Results

The 14 patients who developed HM were significantly younger than those who did not. The eyes with HM exhibited significantly reduced AL (2.8%) compared to those without HM (0.7%). There was no significant difference in CT change between the two groups. The rate of AL reduction was significantly correlated with age, postoperative IOP, and preoperative AL. Post-adjustment logistic regression analysis revealed that eyes with AL reduction rate ≥ 2% had 11.67 higher risk for developing HM (95% confidence interval, 1.28–106.6; P = 0.03).

Conclusions

AL reduction rates ≥ 2% were significantly associated with HM. Excessive reduction in AL, which was seen in eyes with HM, was not an artificial measure resulting from choroidal thickening but rather reflected reductions in the anterior-posterior diameter of the eyeball. Inward collapse of the scleral wall leads to redundancy of the chorioretinal tissue, contributing to the development of HM after TLE.

Evaluation of Corneal Deformation Parameters Provided by the Corvis ST Tonometer After Trabeculectomy

PURPOSE

The aims of this study were to evaluate how the corneal deformation parameters provided by the Corvis ST tonometer (CST) were influenced by pressure-lowering ocular surgery, and to determine the correlations of intraocular pressure (IOP) and axial length (AL) with CST corneal deformation parameters.

METHODS

This prospective 1-month study enrolled 22 subjects (22 eyes) who underwent trabeculectomy combined with mitomycin C. The corneal deformation parameters were measured using the CST. IOP was measured before and after surgery by a Goldmann applanation tonometer and the CST. The central corneal thickness and AL were also recorded. The correlations of the corneal deformation parameters with central corneal thickness, AL, and IOP changes were determined by linear regression analysis.

RESULTS

IOP decreased significantly after surgery. AL was significantly shorter at 1 week after surgery. There were significant changes in the CST parameters time 1, velocity 1, velocity 2, peak distance highest concavity, and deformation amplitude highest concavity at 1 week and 1 month after surgery and in time highest concavity at 1 week after surgery. The change in time 1 was significantly correlated with preoperative IOP and the IOP reductions, and was positively correlated with the decrease in AL at 1 week. The increase in velocity 1 was negatively correlated with preoperative IOP, and IOP reductions. The change in time highest concavity was negatively correlated with IOP before surgery and the decrease in IOP at 1 week.

CONCLUSION

CST is a good choice for measuring IOP, especially when aiming for normalization of IOP after glaucoma surgery.

Changes in anterior ocular structures and macula following deep sclerectomy with collagen implant

PURPOSE

To determine the effect of intraocular pressure (IOP) lowering with deep sclerectomy (DS) on visual acuity, macular structures, and anterior ocular dimensions during the early postoperative period.

METHODS

We prospectively analyzed 35 eyes of 35 patients scheduled for DS. Our focus with the measurements was on early postoperative changes in anterior ocular and macular structures related to IOP lowering during the first month after DS. In addition to a clinical ophthalmologic examination, our measurements included corneal topography, measurement of ocular dimensions with optical biometry, and examination of macular structure with optical coherence tomography. These measurements were repeated 1, 2, and 4 weeks postoperatively.

RESULTS

Best-corrected visual acuity (BCVA) decreased 1 week postoperatively to 0.22 (0.20) LogMAR (p = 0.006). The BCVA then increased to its preoperative level, 0.17 (0.18) (p = 0.28), after 4 weeks. Axial length decreased from 24.12 (1.81) mm to 24.04 (1.81) (p<0.001) 4 weeks postoperatively. The steeper meridian of corneal curvature and average corneal power increased postoperatively; central corneal thickness was decreased. No significant change appeared in other measurements.

CONCLUSIONS

We found changes in corneal curvature and ocular dimensions after DS. These changes were relatively small and do not completely explain the decrease in visual acuity postoperatively. Macular structures showed no changes.

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

Purpose

Choroidal thickness increases linearly with intraocular pressure (IOP) lowering. We studied the relationship between the change in size of the choroidal vasculature and IOP lowering after glaucoma procedures.

Methods

Thirty eyes of twenty-nine patients were examined pre- and postoperatively for up to 6 months with standard clinical assessment, enhanced depth imaging spectral-domain optical coherence tomography (OCT), and axial length measurement. Each enhanced depth imaging spectral-domain OCT image was analyzed using three separate methods to determine the choroidal thickness, choroidal vessel thickness, choroidal interstitial thickness, large choroidal vessel layer thickness, medium choroidal vessel layer thickness, and light-dark ratio. Bivariate linear regression analysis was completed with largest change in IOP as the independent variable. The dependent variables included choroidal thickness, choroidal vessel thickness, and choroidal interstitial thickness, at the largest change in IOP. Multivariable regression analysis using a generalized estimating equation to account for multiple measurements per eye was also completed.

Results

Mean choroidal vessel thickness increases 1.5 μm for every 1 mm Hg decrease in IOP (P < 0.0001; 95% confidence interval [CI], 0.8, 2.1) and choroidal interstitial thickness increases 1.3 μm for every 1 mm Hg change in IOP (P < 0.0001; 95% CI, 0.8, 1.8). There was no significant association between change in IOP and change in large choroidal vessel layer temporally (P = 0.13), nasally (P = 0.20), or subfoveally (P = 0.18). There was also no association between IOP and the light-dark ratio (P = 0.16).

Conclusions

The increase in choroidal thickness at lower IOP is associated with approximately equal increases in its intravascular and extravascular compartments.

Peripapillary Pachychoroid in Nonarteritic Anterior Ischemic Optic Neuropathy

Purpose

This study examined the peripapillary choroidal thickness (PCT) in nonarteritic ischemic optic neuropathy (NAION) in comparison to contralateral eyes and normal eyes.

Methods

We used enhanced depth imaging spectral-domain optical coherence tomography to image the optic nerve head of 20 NAION, 10 contralateral eyes, and 102 normal eyes. Following compensation, the scans were manually delineated to identify relevant surfaces including Bruch's membrane opening (BMO), Bruch's membrane, and anterior sclera. The PCT was defined as the measurement between Bruch's membrane and the anterior sclera and was measured at increasing distance from BMO. Models adjusted for age, BMO area, and axial length were used to compare the mean PCT between NAION and normal eyes, and contralateral eyes and normal eyes. Paired t-tests were used to compare the PCT between NAION and contralateral eyes.

Results

The mean PCT was thicker in NAION and contralateral eyes when compared with normal eyes at all distances from BMO (P < 0.001). The PCT was not significantly thicker in contralateral eyes when compared with affected NAION eyes. Choroidal thickness was thinnest in the inferior quadrant in all eyes regardless of the group.

Conclusions

Increased peripapillary choroidal thickness was noted in both NAION and contralateral eyes. The thicker choroid may be an associated feature or a result of the disorder. Although further longitudinal study is required to determine causation, these findings may suggest that a thickened peripapillary choroid may be a component of the disk-at-risk clinical phenotype.

Changes in the Choroidal Thickness and Axial Length Upon Mannitol Infusion in Patients With Asymmetric Intraocular Pressure

BACKGROUND/AIMS

To evaluate the changes in the choroidal thickness (CT) and axial length (AL) upon systemic mannitol infusion in glaucoma patients with asymmetric intraocular pressure (IOP).

MATERIALS AND METHODS

Forty glaucoma patients with asymmetric IOP, with the IOP of 1 eye ≥40 mm Hg and the fellow eye <25 mm Hg, were administered 150 mL of a 20% mannitol infusion to reduce the IOP. The CT and AL were measured before and an hour after the infusion. The relationship between the IOP reduction and the changes in the CT and AL were investigated.

RESULTS

The mean decrease in the IOP was -14.23 mm Hg (32.15%) and -4.13 mm Hg (21.40%) in the eyes with higher IOP and their fellow eyes, respectively. The mean changes in the subfoveal CT were 19.28 µm (9.20%; P<0.001) and 2.60 µm (1.93%; P=0.452) in the eyes with higher IOP and their fellow eyes, respectively. The mean changes in the AL were -0.10 µm (0.42%; P<0.001) and -0.33 mm (0.14%; P=0.008) in the eyes with higher IOP and their fellow eyes, respectively. Stepwise analysis revealed that the percent IOP change is the most influential factor on the percent change of the subfoveal CT (P<0.0001; R=0.3).

CONCLUSIONS

These results suggest that large IOP changes upon mannitol infusion cause the shortening of the AL in both the eyes and the thickening of the choroid only in the eyes with a higher IOP.

Topographic profile of choroid in eyes after acute primary angle-closure

OBJECTIVE

To characterize and compare the topographic profile of choroid in eyes after acute primary angle-closure (APAC) and in normal controls.

DESIGN, SETTING, AND PARTICIPANTS

A prospective observational study was conducted. Forty-four consecutive patients who had experienced unilateral APAC that was resolved by treatment were recruited. Seventy age- and sex-matched normal individuals were recruited as controls.

METHODS

Enhanced depth imaging-optical coherence tomography was used to measure choroidal thickness (CT) in 9 diffuse locations of macular region. The average CT was compared among each location in the APAC and control groups and between the same locations in the 2 groups.

RESULTS

Variants of CT at different macular locations were found in both groups; it was greatest at subfoveal locations and spread thinner around them, to reach a significant decrease (all p ≤ 0.05) 3 mm away in all directions from the fovea except for the superior direction in normal controls (p = 0.472). Among the 4 directions, the superior had the thickest CT in both groups, followed by the temporal, inferior, and nasal directions in both groups, whereas the APAC had a thicker choroid profile at each location (all p < 0.05). Univariate analysis showed that age, sex, anterior chamber depth, axial length, and spherical equivalent were all associated with the subfoveal choroidal thickness (SFCT) (all p < 0.1). Multivariable linear regression analysis showed that the SFCT was significantly thicker in association with an APAC diagnosis, shorter axial length, greater spherical equivalent refractive error, and younger female subjects (all p ≤ 0.05).

CONCLUSIONS

APAC eyes have a thicker choroid than normal eyes in the macular region, and the increase in CT in APAC eyes follows topographic distribution as in normal control eyes.

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 choroidal thickness after intraocular pressure reduction following trabeculectomy

PURPOSE

To evaluate the changes of peripapillary and subfoveal choroidal thickness (CT) after trabeculectomy.

METHODS

Prospective longitudinal study included 37 eyes with open-angle glaucoma. The subfoveal and peripapillary CT was measured using enhanced depth imaging spectral domain optical coherence tomography before trabeculectomy and 1 week, 3 and 6 months postoperatively. The associations between changes in the CT, intraocular pressure (IOP) and axial length were analysed.

RESULTS

The medium subfoveal CT (IQR) increased from 182 (97) μm at baseline to 267 (107) μm 1 week, 213 (97) μm 3 months and 207 (91) μm 6 months postoperatively (p < 0.001). The peripapillary CT increased in all four quadrants at all follow-ups (p < 0.05). The subfoveal and peripapillary choroidal thickening correlated with the magnitude of IOP reduction (p < 0.05) and axial length shortening (p < 0.01) during whole follow-up period. There was a peripapillary CT increase of 2.9 μm per mmHg of IOP reduction (p < 0.001, CI 1.5-4.4) and 4.8 μm per mm of baseline axial length (p = 0.049, CI 0.03-9.6) 1 week postoperatively after adjustment for baseline IOP. Six months postoperatively, the decrease in axial length was the only factor associated with peripapillary choroidal thickening (p = 0.031; regression coefficient: 73.29 μm/mm, CI 7.1-139.5).

CONCLUSION

Intraocular pressure (IOP) reduction after trabeculectomy caused the increase in subfoveal and peripapillary CT for at least 6 months postoperatively correlating with greater IOP reduction and axial length shortening. In the long term, the decrease in axial eye length, but not IOP, was the only factor to be associated with peripapillary choroidal thickening.

INTRA-SCLERAL PARATHALAMUS IMPLANT: EFFICACY AND SAFETY IN RABBIT EYES

PURPOSE

A variety of anti-glaucomatous shunt designs have been proposed so far. This study evaluates the feasibility of a novel shunt design, the intra-scleral parathalamus implant (IPI), in a rabbit eye model.

METHODS

Ten healthy albino rabbits were included. Measurements of the IOP, using TonoPenXL, as well as ocular rigidity (OR) and aqueous outflow facility (AO), using a previously described methodology, were performed in both eyes of each animal. Subsequently, the IPI was implanted at the left eye of all animals whereas the right eye served as control. Measurements of IOP were repeated at weekly intervals for 2 months postoperatively whereas measurements of OR and AO were repeated at the 1st and 2nd postoperative week.

RESULTS

The IOP decreased significantly whereas the AO increased significantly postoperatively at the operated eyes. A significant postoperative decrease in OR was also recorded at the operated eyes. Respective differences at the fellow eyes were statistically not significant. Two animals developed postoperative complications and were excluded from follow-up.

CONCLUSIONS

Results imply that the implantation of the IPI is feasible in rabbit eyes with significant favorable effects on the IOP, AO and OR.

Evaluation of choroidal thickness using enhanced depth imaging by spectral-domain optical coherence tomography in patients with pseudoexfoliation syndrome

PURPOSE

To investigate the choroidal thickness using optical coherence tomography in the eyes of patients with unilateral and bilateral pseudoexfoliation syndrome and to compare them with healthy controls.

METHODS

We studied four groups: (1) affected eyes from 30 patients with unilateral PEX syndrome affecting the right eye of 17 patients and the left eye of 13 patients; (2) clinically unaffected eyes of 30 patients with unilateral PEX syndrome; (3) the eyes of 30 patients with bilateral PEX syndrome; and (4) the eyes of 30 normal healthy subjects. Choroidal thickness was evaluated using high-speed, high-resolution enhanced depth imaging by spectral-domain optical coherence tomography. Optical coherence tomography features were compared in all groups using the statistical package SPSS v 15.0.

RESULTS

The mean subfoveal choroidal thicknesses were 237.35±58.01 μm in group 1; 330.75±47.84 μm in group 2; 206.3±86.75 μm in group 3; and 311.8±51.42 μm in group 4. Significant differences in the mean subfoveal choroidal thickness were found between groups 1 and 2 (P<0.001), groups 1 and 4 (P=0.004), groups 2 and 3 (P<0.001), and groups 3 and 4 (P<0.001).

CONCLUSION

In this study, it was observed that clinically affected eyes of patients with PEX syndrome have significantly thinner choroids compared with the clinically unaffected eyes of patients with unilateral PEX syndrome and eyes of healthy controls.

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.