Choroidal physiology and primary angle closure disease

Anterior segment features in neovascular glaucoma: An ultrasound biomicroscopy study

PURPOSES

To investigate the features of the anterior segment structures in neovascular glaucoma (NVG) and analyze its differences from primary angle-closure glaucoma (PACG).

METHODS

This study included patients who were first diagnosed with monocular NVG and PACG at the Affiliated Eye Hospital of Nanchang University during August 2019 to June 2022. Ultrasound biomicroscopy (UBM) was used to measure the anterior segment parameters of those eyes, including anterior chamber depth (ACD), anterior chamber width (ACW), anterior chamber area (ACA), iris area (IA), maximum iris thickness (ITMAX), middle iris thickness (ITMID), iris curvature (IC), lens vault (LV), angle opening distance (AOD500), trabecular iris angle (TIA500), trabecular-iris space area (TISA500) and peripheral anterior synechia (PAS) length.

RESULTS

In this study, paired samples t-test showed that IA [1.170(0.324) mm2], ITMAX [0.368(0.079) mm], ITMID [0.280(0.062) mm] and IC [0.147(0.037) mm] of NVG were smaller than F-NVG [2.058(0.195) mm2, 0.611(0.045) mm, 0.415(0.049) mm and 0.272(0.077) mm], the AOD500, TIA500, and TISA500 of NVG were also smaller than F-NVG. Independent samples t-test showed that ACD [2.349(0.350) mm] and ACA [16.326(3.547) mm2] of NVG were larger than PACG [1.971(0.240) mm, 12.030(1.860) mm2], but the IA [1.170(0.324) mm2], ITMAX [0.368(0.079) mm], ITMID [0.280(0.062) mm], IC [0.147(0.037) mm] and LV [0.436(0.172 mm)] were smaller than PACG [1.740(0.294) mm2, 0.548(0.084) mm, 0.404(0.065) mm, 0.283(0.060) mm and 0.737(0.196) mm]. Among the 16 patients with 360° angle-closure NVG, the PAS length was 0.834 (0.326) mm, which exceeded the Schwalbe line.

CONCLUSION

In NVG, the iris is atrophied, thinned, and straight, while the ACD is normal or slightly shallow. In 360° angle-closure NVG, the PAS length exceeds the Schwalbe line, presenting a pseudo angle phenomenon and a hockey stick sign. Notably, the anterior segment structure morphology of NVG exhibit differences from those of PACG.

Comparison of the Choroid in Primary Open Angle and Angle Closure Glaucoma Using Optical Coherence Tomography

PRCIS

The current study highlights distinct choroidal alterations in primary open angle (POAG) and primary angle closure (PACG) glaucomas, underscoring the potential of the Choroidal Vascularity Index (CVI) as a valuable indicator for understanding glaucoma pathogenesis.

PURPOSE

To evaluate choroidal structural changes in patients with POAG and PACG and healthy controls utilizing the CVI and subfoveal choroidal thickness by enhanced depth imaging optical coherence tomography.

METHODS

This study was cross-sectional. A total of 171 eyes of 171 subjects, comprising 69 eyes with untreated POAG, 58 eyes with untreated PACG, and 44 healthy eyes, were enrolled in this study. Subfoveal choroidal thickness, luminal area (LA), stromal area (SA), and total choroidal area were measured on enhanced depth imaging-optical coherence tomography scans. The CVI parameter is calculated as the proportion of LA to the total choroidal area.

RESULTS

This study included 69 patients with POAG with a mean age of 51.4 ± 13.3 years, 58 patients with PACG with a mean age of 57.0 ± 7.3 years, and 44 healthy subjects with a mean age of 51.11 ± 10.7 years. The CVI in the POAG and PACG groups was significantly lower than that in the control group ( P = 0.001 and P = 0.005, respectively); however, not significantly different between the two glaucoma groups ( P = 1.000). POAG eyes had significantly lower LA than PACG and controls ( P = 0.014 and P = 0.049, respectively), whereas PACG eyes had significantly greater SA than controls ( P = 0.041).

CONCLUSIONS

The CVI of POAG and PACG eyes was significantly lower than that of normal eyes. A reduced LA was observed mainly in eyes with POAG, and an increased SA was observed mainly in eyes with PACG. The role of the choroid may differ between POAG and PACG eyes.

Association of body mass index and PXDNL gene variants with acute primary angle closure in southern Chinese population

This study aimed to evaluate the association of body mass index (BMI) and the weight-related gene, peroxidasin-like (PXDNL), with acute primary angle closure (APAC) and primary angle-closure glaucoma (PACG) in southern Chinese population. Total 4700 study subjects (1024 APAC, 781 PACG, and 2895 control subjects) with complete ophthalmic examinations were enrolled into this study. The association of BMI with APAC, PACG and ocular biometric parameters was evaluated. Three PXDNL missense variants were genotyped by TaqMan assay, and their association with APAC and PACG was also investigated. Multivariable logistic regression analysis showed that BMI and body weight were significantly associated with both APAC and PACG (P < 0.01). Multiple linear regression analysis demonstrated that each 1 kg/m2 increased in BMI was associated with 0.038 mm increase in axial length, 0.018 mm increase in central anterior chamber depth, 0.002 mm increase in lens position, 0.012 mm increase in corneal diameter and 0.014 mm decrease in lens thickness among the APAC subjects (P < 0.001), but not with PACG. Genetic association analysis identified that PXDNL rs11985241-rs16916207 CT haplotype conferred a higher risk to APAC (OR = 1.25, P = 0.004) than the TG haplotype, but not with PACG. The APAC subjects carrying the rs11985241 C or rs16916207 T alleles showed significantly lower weight than those carrying the corresponding protective alleles. In summary, this study revealed that lower BMI could be associated with higher risk of APAC. PXDNL could be a new associated gene for APAC.

Nano-based eye drop: Topical and noninvasive therapy for ocular diseases

Eye drops are the most accessible therapy for ocular diseases, while inevitably suffering from their lower bioavailability which highly restricts the treatment efficacy. The introduction of nanotechnology has attracted considerable interest as it has advantages over conventional ones such as prolonged ocular surface retention time and enhanced ocular barrier penetrating properties, and achieving higher bioavailability and improved treatment efficacy. This review describes various ocular diseases treated with eye drops as well as the physiological and anatomical ocular barriers faced with through drug administration. It also summarizes the recent advances regarding the utilization of nanotechnology in developing eye drops, and how to optimize the nanocarrier-based ocular drug delivery systems. The prospective future research directions for nano-based eye drops are also discussed here.

Minimally Invasive Glaucoma Surgery in Primary Angle-Closure Glaucoma

Primary angle-closure glaucoma (PACG) is responsible for half of the glaucoma-related blindness worldwide. Cataract surgery with or without trabeculectomy has been considered to be the first-line treatment in eyes with medically uncontrolled PACG. While minimally invasive glaucoma surgery has become an important surgical approach for primary open-angle glaucoma, its indications and benefits in PACG are less clear. This review summarizes the efficacy and safety profile of minimally invasive glaucoma surgery in PACG to unfold new insights into the surgical management of PACG.

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

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

Clinical observation of macular choroidal thickness in primary chronic angle-closure glaucoma

PURPOSE

To comparatively analyze differences in macular choroidal thickness and volume in primary chronic angle-closure glaucoma (PACG) eyes.

METHODS

Thirty-one PACG patients were sequentially selected for this case-control study. Thirty-one eyes with PACG were included in group A, 31 fellow eyes were included in group B, and group C included 67 normal eyes. Enhanced-depth imaging optical coherence tomography (EDI-OCT) was used to measure choroidal thickness and volume.

RESULTS

The choroidal thicknesses and volumes of the central subfield macula (CSM), nasal inner macula (NIM), temporal inner macula (TIM), inferior inner macula (IIM), temporal outer macula (TOM), inferior outer macula (IOM), and mean macula (MM) in group A were all higher than those in group C (P < 0.05). The choroidal thicknesses and volumes of the NIM, superior inner macula (SIM), IIM, nasal outer macula (NOM), and MM in group B were all higher than those in group C (P < 0.05). No statistically significant differences were found between groups A and B (P > 0.05). The choroidal thicknesses of different macular regions in group A were not correlated with the mean defect (MD).

CONCLUSION

Increased macular choroidal thickness may be a common anatomical characteristic of PACD eyes. Macular choroidal thickness is not a good marker for assessing PACG severity.

[Iris shape change and risk of anterior chamber angle closure]

Potential obstruction of the anterior chamber angle by iris root is a key factor of the pathogenesis of angle-closure glaucoma. Development and adoption of ultrasound biomicroscopy and optical coherence tomography in clinical practice have significantly expanded the capabilities of studying the structures of the anterior eye segment in terms of angle closure risk factors through improving visualization depth and quality of examination, including different variants of iris structure and potential changes of its shape in mydriasis. The article reviews various studies dedicated to the progression of primary angle-closure glaucoma and its dependence on the biometric parameters of the eye and changes in pupil size.

Investigation of Corneal Astigmatism in Chinese Patients With Primary Angle Closure Disease

PURPOSE

The purpose of this study was to analyze the demographics and distribution of corneal astigmatism before lens extraction in patients with primary angle closure disease (PACD).

METHODS

Preoperative partial coherence interferometry was performed in patients with PACD. The demographic and biometric data, including corneal astigmatism and keratometry (K), were recorded.

RESULTS

The study comprised 808 cases (1001 eyes) with a mean age of 67.66±9.07 years, and the mean axial length was 22.55±0.89 mm. The mean corneal astigmatism was 1.08±0.78 diopter (D). Corneal astigmatism was between 0.25 D and 1.25 D in 66.50% of the eyes, 1.25 D or higher in 29.68% of the eyes and <0.25 D in 3.82% of the eyes. The corneal astigmatism of primary angle closure suspect (PACS), primary angle closure (PAC) and primary angle closure glaucoma (PACG) were 1.08±0.77 D, 0.98±0.62 D, and 0.89±0.69 D, respectively. In total, 50.60% of the eyes were classified as astigmatism against the rule (ATR), 28.69% of the eyes were with the rule, and 20.71% of the eyes were oblique. ATR astigmatism increased significantly with age (P<0.001). After matching, corneal astigmatism of PACD was 1.07±0.77 D, although it was statistically significantly higher than that of ARC (0.98±0.66 D, P=0.018), the 2 demonstrated no clinical difference.

CONCLUSIONS

The results provide normative data of corneal astigmatism for PACD patients. Corneal astigmatism was mainly distributed between 0.25 D and 1.25 D. The findings largely concur with published results in age-related cataract subjects.

Changes in peripapillary choroidal thickness in patients with multiple sclerosis

PURPOSE

To study peripapillary choroidal thickness (PPCT) around the optic disc and establish zones using a new swept source optical coherence tomography (SS-OCT) device. To evaluate PPCT differences between patients with multiple sclerosis (MS) and age- and sex-matched healthy controls.

METHODS

A total of 102 healthy subjects and 51 patients with MS were consecutively recruited. Healthy subjects were divided into teaching (n = 51, used to establish choroidal zones) and validating (n = 51, used to compare measurements with MS patients) populations. An optic disc 6.0 × 6.0-mm three-dimensional scan was obtained using SS-OCT Triton. A 26 × 26 cube-grid centred on the optic disc was generated automatically to measure PPCT. Four choroidal zones were established and used to compare PPCT between healthy controls and patients with MS.

RESULTS

Peripapillary choroidal thickness (PPCT) was significantly thinner in patients in all concentric zones (p ≤ 0.0001): 134.02 ± 16.59 μm in MS group versus 171.56 ± 12.43 μm in the control group in zone 2; 182.23 ± 20.52 versus 219.03 ± 17.99 μm, respectively, in zone 3; and 223.52 ± 10.70 versus 259.99 ± 10.29 μm, respectively, in zone 4. The choroidal thinning in the MS group tended to decrease as we distanced from the optic nerve head. Peripapillary choroidal thickness (PPCT) had a similar pattern in controls and MS; it was thicker in the superior region, followed by temporal, nasal and inferior regions.

CONCLUSION

Patients with MS showed peripapillary choroidal thinning when compared with healthy subjects in all zones around the optic disc. Peripapillary choroidal tissue shows a concentric pattern, increasing in thickness when increasing the distance from the optic nerve. The new SS-OCT could be useful for evaluating choroidal thinning in clinical practice.

Effects of Choroidal Thickness on Refractive Outcome Following Cataract Surgery in Primary Angle Closure

Purpose

To identify the preoperative biometric factors, including subfoveal choroidal thickness (CT), associated with refractive outcome after cataract surgery in eyes with primary angle closure (PAC).

Methods

This study included 50 eyes of 50 PAC patients who underwent uneventful cataract surgery. Preoperatively, anterior segment parameters including anterior chamber depth (ACD) and lens vault were determined by anterior segment optical coherence tomography. Subfoveal CT was measured by spectral domain optical coherence tomography enhanced depth imaging before and at one month after surgery. Mean refractive error (MRE) was calculated as the difference in spherical equivalent between actual postoperative refraction determined one month postoperatively and that predicted using each of three IOL calculation formulas (SRK/II, SRK/T, and Haigis). Regression analyses were performed to investigate potential associations between MRE and putative factors.

Results

Mean ACD was 1.9 ± 0.4 mm, and preoperative subfoveal CT was 250.8 ± 56.9 µm. The SRK/T (MRE, 0.199 ± 0.567 diopters [D]) and Haigis (MRE, 0.190 ± 0.727 D) formulas showed slight hyperopic shift, while the SRK/II formula demonstrated a myopic shift (MRE, −0.077 ± 0.623 D) compared with that expected after cataract surgery. Mean absolute refractive error was not significantly different between formulas. Higher preoperative lens vault and shallower ACD were associated with a hyperopic shift in all formulas, but not in a statistically significant manner. Thicker preoperative subfoveal choroid was associated with a myopic shift after cataract surgery in all formulas (SRK/II: β = −0.511, p < 0.001; SRK/T: β = −0.652, p < 0.001; Haigis: β = −0.671, p < 0.001). Greater postoperative reduction of subfoveal CT was associated with a myopic shift after cataract surgery in all formulas (SRK/II: β = −0.511, p < 0.001; SRK/T: β = −0.652, p < 0.001; Haigis: β = −0.671, p < 0.001).

Conclusions

Our results indicate that preoperative subfoveal CT and the difference between pre- and postoperative subfoveal CT are significant factors for predicting refractive error after cataract surgery in PAC patients. These findings should be considered when performing cataract surgery to optimize visual outcomes.

Biometric Differences between Unilateral Chronic Primary Angle Closure Glaucoma and Fellow Non-Glaucomatous Eyes

PURPOSE

To compare biometric differences between eyes with unilateral chronic primary angle-closure glaucoma (PACG) and fellow non-glaucomatous eyes in the same patient.

METHODS

Clinical data and imaging records of 17 patients with unilateral PACG were retrospectively reviewed. The fellow eyes with primary angle-closure (PAC) or primary angle-closure suspected (PACS) were grouped in Group 1. The PACG eyes were set as Group 2. The biometric parameters of both eyes were measured by IOL-Master, anterior segment optical coherence tomography (AS-OCT), and swept source OCT.

RESULTS

The iris area in Group 1 was significantly thicker than that in Group 2 (1.590 ± 0.267 versus 1.365 ± 0.352, P = 0.016). Choroidal thickness in the macular region was thicker in Group 1 than in Group 2, with statistical significance at inner temporal grid (282.7 ± 121.1 versus 191.6 ± 90.3, P = 0.036), central field (297.4 ± 130.6 versus 200.1 ± 96.3, P = 0.029), inner nasal grid (283.1 ± 128.3 versus 194.8 ± 91.8, P = 0.040), and average value (265.3 ± 105.6 versus 191.1 ± 87.0, P = 0.049). Group 1 also had thicker peripapillary choroidal thickness at 1 o'clock (141.4 ± 68.4 versus 101.8 ± 39.0, P = 0.025) and 12 o'clock (141.5 ± 82.3 versus 104.5 ± 44.6, P = 0.037) compared to Group 2. The multivariate logistic regression analyses showed that only intraocular pressure was independently associated with PACG and explained 58.3% variance of PACG.

CONCLUSIONS

In unilateral PACG, there was significant inter-eye difference in anterior and posterior segment parameters. Longitudinal comparisons are required to further understand the differences in pathology of angle closures.

Comparison of peripapillary choroidal thickness between healthy subjects and patients with Parkinson's disease

Purpose

To study peripapillary choroidal thickness (PPCT) in healthy subjects using swept-source optical coherence tomography (SS-OCT), and to evaluate PPCT differences between Parkinson´s disease (PD) patients, and age- and sex-matched healthy controls.

Design

Case-control study

Methods

80 healthy subjects and 40 PD patients were consecutively recruited in this single institution study. The healthy subjects were divided into two populations: a teaching population (n = 40, used to establish choroidal zones) and a validating population (n = 40, used to compare measurements with PD patients). An optic disc 6.0×6.0 mm three-dimensional scan was obtained using Deep Range Imaging (DRI) OCT Triton. A 26×26 cube-grid centered on the optic disc was generated to automatically measure choroidal thickness. Five concentric choroidal zones were established and used to compare PPCT between healthy and PD patients.

Results

PPCT was significantly thicker in PD patients compared with controls in all four concentric zones evaluated (p≤0.0001). PPCT followed a similar pattern in controls and PD; it was thicker in the temporosuperior region, followed by the superior, temporal, nasal, and inferior regions.

Conclusion

PD patients presented with an increased PPCT in all zones surrounding the optic disc compared with healthy subjects. The peripapillary choroidal tissue showed a concentric pattern, with the thickness increasing with increasing distance from the optic nerve. SS-OCT could be useful for evaluating choroidal thinning in clinical practice.

Anterior but not posterior choroid changed before and during Valsalva manoeuvre in healthy Chinese: a UBM and SS-OCT study

PURPOSE

To determine if the anterior choroid is involved in ocular change during the Valsalva manoeuvre (VM).

MATERIALS AND METHODS

Fifty-three healthy volunteers aged 18-65 years with normal visual field test results and no history of intraocular pressure (IOP) exceeding 21 mm Hg were recruited. Anterior and posterior choroidal changes before and during VM were recorded by ultrasound microscope and swept-source optical coherence tomography, respectively. Parameters of the anterior segment included ciliary body thickness (CBT0), thickness of the choroid at a distance of 4 mm from the root of the iris (CT4), anterior placement of the ciliary body (APCB) and trabecular-ciliary angle (TCA). Thickness of different layers of retina and posterior choroid were also measured and compared before and during VM. IOP, blood pressure (BP), heart rate (HR), axial length, spherical equivalent refractive error and pupil diameter (PD) were also recorded and analysed.

RESULTS

VM caused elevated IOP, systolic BP, diastolic BP and increased HR. There was a significant increase in anterior parameters including CBT0, CT4 and APCB (p<0.001), but not in TCA or PD (p>0.05). The mean change of CBT0, CT4 and APCB were: from 1.00±0.09 mm to 1.11±0.10 mm (p<0.001), from 0.29±0.04 mm to 0.36±0.05 mm (p<0.001), from 0.76±0.11 mm to 0.88±0.13 mm (p<0.001), respectively. However, there is no significant change in posterior choroid (from 215.74±60.23 µm to 214.82±61.32 µm, p=0.17).

CONCLUSION

We found that VM did not affect the posterior choroid, but it did cause thickening of the anterior choroid and the ciliary body, both of which led to a larger anterior placement of the ciliary body and a narrowed anterior chamber. The anterior (but not the posterior) choroid could be related to IOP elevation and a narrowed anterior chamber in primary angle closure diseases.

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.

Interocular symmetry of the peripapillary choroidal thickness and retinal nerve fibre layer thickness in healthy adults with isometropia

Background

The aim of this study was to determine the interocular differences in the peripapillary retinal nerve fibre layer (RNFL), peripapillary choroidal thickness (PCT) and subfoveal choroidal thickness (SFCT) in healthy adults with isometropia, using enhanced depth imaging optical coherence tomography (EDI SD-OCT).

Methods

One hundred healthy Chinese adults with spherical equivalents of ≤ ±3 dioptres and interocular differences of <0.5 dioptres were prospectively enrolled in this study. They underwent RNFL and PCT measurements via EDI SD-OCT, with a 3.4 mm scan circle centred on the optic nerve head. Subfoveal choroidal thickness (SFCT) measurements were also taken with a horizontal line scan centred on the macula. Right and left eyes were compared by a paired t-test, and the interocular differences were calculated. The agreement and correlations of the RNFLs, PCTs and SFCTs between the right and left eyes were analysed.

Results

Eighty-six subjects (172 eyes) were included in the final analysis, consisting of 44 (51.6 %) males and 42 (48.8 %) females; 55 (63.9 %) had emmetropia and 33 (36.1 %) had ametropia. The RNFL was statistically significantly thicker in the right eyes when compared to the left eyes in the temporal quadrant, and thinner on average in the nasal superior quadrant (p < 0.05). However, the differences in the choroidal thicknesses in all of the quadrants between the right and left eyes were not statistically significant. The tolerance limits of the average RNFL were −21.1 μm and 7.1 μm, and the mean and standard deviation of the interocular difference in the average PCT was −2.2 ± 24.2 μm. The RNFLs and PCTs in all of the locations in the right eyes were significantly correlated with those in the left eyes. However, no significant associations between the age, sex, interocular asymmetry of spherical the equivalent or interocular differences in the RNFL and PCT were detected.

Conclusion

The PCT did not differ significantly between the right and left eyes, although interocular asymmetry of the RNFL existed in this Chinese population with isometropia.

Changes in Anterior Segment Morphology After Laser Peripheral Iridotomy in Acute Primary Angle Closure

PURPOSE

To evaluate the anterior segment biometric changes measured by anterior segment optical coherence tomography (AS-OCT) in acute primary angle closure (APAC) after laser peripheral iridotomy (LPI).

DESIGN

Prospective interventional study.

METHODS

In this clinic-based study, 52 eyes of 52 patients with resolved APAC attack who underwent LPI were enrolled. Subjects underwent complete ophthalmic examination and AS-OCT imaging before and 6 weeks after LPI. Anterior chamber depth (ACD), anterior chamber area (ACA), iris thickness (IT), iris area, iris curvature, lens vault (LV), anterior vault, angle opening distance (AOD500, AOD750), and trabecular iris space area (TISA500, TISA750) were measured in qualified images and compared before and after LPI. A linear mixed-model analysis was performed for potential predictors of change in AOD750. Main outcome measure was change in AOD750 after LPI.

RESULTS

The mean age of participants was 60.7 ± 9.2 years. Mean angle width (Shaffer grade) changed from 0.25 ± 0.34 at baseline to 1.22 ± 0.86 after LPI (P < .001). However, 25 nasal angles (48.0%) and 28 temporal angles (53%) had iridotrabecular contact after LPI. All angle parameters (AOD500, AOD750, TISA500, TISA750; P ≤ .03), ACD (P = .001), and ACA (P < .001) increased significantly after LPI. Iris curvature and LV were reduced (P = .01 for both) after LPI, but there was no significant change in IT and iris area. After multivariate analysis, pre-LPI AOD750 was the only factor associated with change in AOD750 (β = -0.992, P = .02). Exaggerated LV, defined as LV greater than one-third of the anterior vault (sum of LV and ACD), was present in 61.5% of the cases (32 eyes). The extent of change in angle parameters was not significantly different between groups with and without exaggerated LV after LPI.

CONCLUSION

This study confirms that LPI results in a significant increase in the angle width, ACD, and ACA as well as flattening of the iris in APAC eyes. The extent of angle deepening is inversely related to baseline angle width. The lens shifts posteriorly after resolution of attack, especially in those with greater lens vault.