Iris ischaemic changes and visual outcome after acute primary angle closure

Clinical presentation of acute primary angle closure during the COVID-19 epidemic lockdown

Purpose

This study aimed to investigate the clinical presentation of acute primary angle closure (APAC) during the COVID-19 epidemic lockdown in Wuhan.

Methods

Consecutive patients seeking APAC treatment at the Wuhan Aier Eye Hospital during the 76 days (January 23-April 8, 2020) when the lockdown policy was implemented due to the COVID-19 pandemic were compared to those during the same period the following year (January 23-April 8, 2021), when the lockdown policy was not implemented. The cohorts were compared to assess demographic variables and clinical presentations.

Results

A total of 54 patients (64 eyes) were included in the 2020, compared with 46 patients (51 eyes) in the 2021. Demographic factors were similar between the groups. Significantly more patients developed blindness in the 2020 cohort (21.87%) than in the 2021 cohort (7.84%). Patients in the 2020 showed a longer time from symptom to treatment (241.84 ± 211.95 h in 2020 vs. 121.53 ± 96.12 h in 2021; P = 0.001), higher intraocular pressure at presentation (52.63 ± 12.45 mmHg in 2020 vs. 45.16 ± 9.79 mmHg in 2021; P = 0.001), larger pupil diameter (5.47 ± 1.62 mm in 2020 vs. 4.33 ± 1.27 mm in 2021; P = 0.001), and more glaucomatous optic neuropathy diagnoses [20/64 eyes (31.25%) in 2020 vs. 7/51 eyes (13.73%) in 2021; P = 0.03].

Conclusion

The time between the onset of APAC symptoms and its treatment during the COVID-19 epidemic lockdown was significantly prolonged, which increased the blindness rate of APAC patients.

Changes of macular blood flow and structure in acute primary angle closure glaucoma

PURPOSE

We assessed the relationship between acute primary angle closure glaucoma (APACG) severity and macular microcirculation, as well as the diagnostic ability of blood flow and macular structural parameters on optical coherence tomography angiography (OCTA) for APACG.

METHODS

APACG patients were assigned to mild, moderate, and severe groups in this cross-sectional study. Age-matched primary angle closure suspect (PACS) and healthy control groups were also recruited. The vessel density (VD) and foveal avascular zone (FAZ) in each macular superficial area were measured using OCTA. The retinal nerve fiber layer thickness (RNFLT) and ganglion cell complex thickness (GCCT) of the corresponding regions were measured using OCT.

RESULTS

All parameters in the control, PACS, and mild APACG groups differed significantly from those in the moderate and severe APACG groups (all P < 0.05). VD and RNFLT showed high and moderate diagnostic ability, respectively, to distinguish moderate APACG from PACS, with significant differences (P < 0.05) in areas under the receiver operating characteristic curve (AUCs) for VD and RNFLT in six macular areas. The diagnostic abilities of VD and RNFLT for distinguishing severe APACG from PACS were increased, with significant differences in the AUCs for VD and RNFLT in five macular areas (P < 0.05). All macular VDs and GCCTs were similar among the three APACG groups (P > 0.05).

CONCLUSIONS

Damage to the VD and FAZ in the macula increased with APACG severity. VD in the macular superficial layer showed a higher diagnostic ability than RNFLT, which was equivalent to that of GCCT.

Macular vessel density and foveal avascular zone parameters in patients after acute primary angle closure determined by OCT angiography

This study analyzed the optical coherence tomography angiography (OCTA) macular parameters in primary angle-closure glaucoma (PACG) patients after acute primary angle closure (APAC) episodes. Thirty-three patients with 33 APAC eyes and 33 primary angle closure suspect (PACS) eyes and 33 age-matched normal subjects (controls) were enrolled. Macular vessel density (VD) in central, inner, outer and full regions and foveal avascular zone (FAZ) parameters (area, perimeter and circularity index) were compared between APAC, PACS, and control eyes. For resolved APAC eyes, the VD in each macular region was significantly lower than that in control eyes, with less central and inner macular VD than PACS eyes. The central macular VD was significantly lower in PACS eyes than in controls. There was no difference in FAZ area and perimeter between APAC, PACS, and control eyes. FAZ circularity was highest in control eyes, followed by PACS eyes, and lowest in APAC eyes. The AUC, sensitivity and specificity of FAZ circularity were 0.944, 93.9% and 84.8%, respectively, in APAC eyes and 0.881, 84.8% and 81.8%, respectively, in PACS eyes. Therefore, FAZ circularity had the best discrimination capability for detecting both APAC and PACS eyes. Macular assessment with OCTA could provide an accurate early-stage diagnostic tool for PACG.

A Minimally Invasive Experimental Model of Acute Ocular Hypertension with Acute Angle Closure Characteristics

Purpose

To describe a minimally invasive experimental model of acute ocular hypertension (OHT) with characteristics of acute angle closure (AAC).

Methods

Adult C57/Bl6 mice (n = 31) were subjected to OHT in one eye using a modified circumlimbal suture technique that elevated intraocular pressure (IOP) for 30 minutes. Contralateral un-operated eyes served as controls. IOP, anterior segment optical coherence tomography, and fundus fluorescein angiography (FFA) were performed. The positive scotopic threshold response (pSTR) and a-wave and b-wave amplitudes were also evaluated. Retinal tissues were immunostained for the retinal ganglion cell (RGC) marker RBPMS and the glial marker GFAP.

Results

OHT eyes developed shallower anterior chambers and dilated pupils. FFA showed focal leakage in 32.2% of OHT eyes, but in none of the control eyes. pSTR was significantly reduced at week 1 in OHT eyes compared to control eyes (57.3 ± 7.2 µV vs. 106.9 ± 24.8 µV; P < 0.05), but a- and b-waves were unaffected. GFAP was upregulated in OHT eyes but not in control eyes or eyes that had been sutured without OHT. RGC density was reduced in OHT eyes after 4 weeks (3857 ± 143.8) vs. control eyes (4469 ± 176.0) (P < 0.05).

Conclusions

Our minimally invasive model resulted in acute OHT with characteristics of AAC in the absence of non-OHT-related neuroinflammatory changes arising from ocular injury alone.

Translational Relevance

This model provides a valuable approach to studying specific characteristics of a severe blinding disease in an experimental setting. Focal areas of ischemia were demonstrated, consistent with clinical studies of acute angle closure patients elsewhere, which may indicate the need for further research into how this could affect visual outcome in these patients.

Higher TGF-β1, TGF-β2, MMP-2, and TIMP-1 Levels in the Aqueous Humor of Patients with Acute Primary Angle Closure

PURPOSE

To assess the quantitative differences in the levels of members of the transforming growth factor (TGF-β), matrix metalloproteinase (MMP), and tissue inhibitor of MMP (TIMP) families in the aqueous humor (AH) between patients with acute primary angle closure (APAC) and those with cataract only.

METHODS

AH samples were collected from 26 patients with APAC and cataract as well as 26 patients with age-related cataract only. Multiplex assays were used to measure the concentrations of TGF-β1, TGF-β2, and TGF-β3; MMP-1, MMP-2, MMP-7, MMP-9, and MMP-10; and TIMP-1 and TIMP-2.

RESULTS

The concentrations of TGF-β1, TGF-β2, MMP-2, (p < 0.001), and TIMP-1 were significantly higher (all p < 0.001) in AH samples from patients with APAC versus cataract only. Conversely, the AH concentrations of MMP-7 (p = 0.524), MMP-9 (p = 0.103), MMP-10 (p = 0.111), and TIMP-2 (p = 0.059) did not significantly differ between the groups. The concentrations of TGF-β3 and MMP-1 were below the respective detection limits in most AH samples.

CONCLUSION

The AH levels of TGF-β1, TGF-β2, MMP-2, and TIMP-1 were elevated in APAC eyes. Such altered protein levels could induce abnormal deposition of extracellular matrix in the trabecular meshwork, resulting in an increase in aqueous outflow resistance and, thereby, providing a possible explanation of the mechanism of residual glaucoma after cataract surgery.

Changes in Optic Nerve Head Vessel Density After Acute Primary Angle Closure Episode

Purpose

To evaluate the changes in circumpapillary vessel density (cpVD) and retinal nerve fiber layer (RNFL) thickness after an acute primary angle closure (APAC) episode.

Methods

Twenty-eight patients (28 pair of eyes) with unilateral APAC and 39 normal subjects (64 eyes) were included in this prospective, observational study. cpVD as measured by optical coherence tomography angiography and RNFL thickness as measured by spectral-domain optical coherence tomography were compared at 6 weeks after an APAC episode between affected, unaffected, and normal eyes. cpVD and RNFL thickness at 1 week and 6 weeks after APAC were also compared in APAC eyes in qualified images.

Results

At 6 weeks, cpVD was significantly lower in APAC eyes (57.3% ± 6.8%), compared to fellow eyes (63.1% ± 3.5%) and control eyes (63.6% ± 3.4%) (P < 0.001). There was diffuse microvascular dropout with greater vessel density loss in the superonasal sector. APAC eyes had thinner RNFL globally and in each sector (except temporal and nasal sectors) than in fellow and normal eyes at 6 weeks. cpVD in the affected eyes was significantly greater at 1 week (56.3% ± 5.3%) than values at 6 weeks (53.5% ± 7%) (P = 0.003) but less than cpVD in the fellow eyes (62.4% ± 5.0%) (P < 0.001). RNFL thickness for the APAC eyes at 1 week (120.6 ± 18.0 μm) was greater than the analogous values for affected eyes (90.1 ± 13.2 μm; P = 0.037) and fellow eyes at 6 weeks (102.5 ± 5.7 μm; P = 0.001).

Conclusions

Vessel density decreased over 6 weeks after an APAC episode compared with the contralateral unaffected eyes. In contrast, there was an initial increase in RNFL thickness that was followed by a subsequent decrease.

Vascular Endothelial Growth Factor is Increased in Aqueous Humor of Acute Primary Angle-Closure Eyes

PURPOSE

To measure and compare the levels of vascular endothelial growth factor (VEGF) in the aqueous humor of patients with acute primary angle closure (APAC), primary angle-closure glaucoma (PACG), and normal cataract (controls).

METHODS

Aqueous humor samples were prospectively collected from 38 APAC eyes, 36 PACG eyes, and 25 nonglaucomatous cataract control eyes. The levels of aqueous humor VEGF were measured using enzyme-linked immunoassays. The clinical characteristics of participants were also collected for correlation analysis.

RESULTS

VEGF was detected in aqueous humor samples of 35 of 38 APAC patients (mean±SE of the mean, 935±258 pg/mL), 30 of 36 PACG patients (165±37.5 pg/mL), and 16 of 25 cataract controls (69.5±13.5 pg/mL). The mean concentration of VEGF in APAC eyes was 13.5 and 5.7 times higher than that in controls and PACG eyes, respectively, and these differences were statistically significant (both P<0.0167). In the correlation analysis that included all participants, the aqueous humor VEGF level was found to correlate negatively with axial length (ρ=-0.342, P=0.001), and positively with intraocular pressure (ρ=0.434, P<0.001).

CONCLUSIONS

VEGF was significantly increased in aqueous humor of APAC eyes. An increase in aqueous humor VEGF may be the result of the characteristic ocular ischemia and hypoxia observed in APAC eyes as a consequence of sudden excessive increases in intraocular pressure during the acute episode.

Peripapillary retinal vessel density in eyes with acute primary angle closure: an optical coherence tomography angiography study

PURPOSE

The purpose was to investigate peripapillary retinal vessel density in resolved acute primary angle closure (APAC) eyes.

METHODS

This was a prospective, cross-sectional observational study. Thirty-four eyes of 34 patients with unilateral APAC were included, together with the fellow eyes with primary angle closure suspect (PACS) as controls. Peripapillary retinal vessel density was measured using optical coherence tomography (OCT) angiography. Peripapillary retinal vessel density was compared in both eyes and the potential relationship with visual field (VF) test results was evaluated.

RESULTS

After an acute attack, the peripapillary retinal vessel density was lower in the APAC than in the PACS eyes (79.3 ± 8.2 versus 85.6 ± 4.9, respectively; P = 0.001). The VF mean deviation (MD) (-7.7 ± 6.7 versus -3.3 ± 1.8 dB, P = 0.002), and the pattern standard deviation (PSD) (4.6 ± 3.3 versus 2.4 ± 0.9 dB, P = 0.001) were worse for the APAC than the PACS eyes, but both had similar thicknesses of the retinal nerve fiber layer (RNFL) (111.8 ± 9.6 versus 114.1 ± 29.1 μm, P = 0.880) and ganglion cell complex (GCC) (94.7 ± 7.5 versus 91.8 ± 9.3 μm, P = 0.328). The peripapillary retinal vessel density was significantly correlated with the VF MD (vessel density: r = 0.455, P = 0.008) and PSD (vessel density: r = -0.592, P < 0.001) in the APAC eyes.

CONCLUSIONS

Even when IOP was normalized after the acute attack, the APAC eyes had a lower peripapillary retinal vessel density, which was correlated with the VF values. OCT angiography is a reliable method for detecting vascular changes in glaucomatous eyes that show no thinning of the RNFL and GCC.

Anterior segment morphology after acute primary angle closure treatment: a randomised study comparing iridoplasty and medical therapy

PURPOSE

To compare the effect of argon laser peripheral iridoplasty (ALPI) and conventional medical therapy in the immediate treatment of acute primary angle closure (APAC) using anterior segment optical coherence tomography (ASOCT).

METHODS

In this single tertiary centre, prospective comparative study, we randomised 30 consecutive patients with unilateral APAC into two groups: ALPI and medical treatment (n=15 each). Immediately before and 1 h after either intervention, ASOCT imaging was performed. Custom software was used to measure pupil diameter, anterior chamber depth, iris curvature (I-Curv), iris area (I-Area), and the angle opening distance (AOD750), trabecular iris space area (TISA750) and the iris thickness at 750 µm from the scleral spur. The main outcome measure was the change in anterior segment biometrical parameters.

RESULTS

The mean age of the patients was 62.8±7.7 years; 13 (43.3%) were male. APAC eyes treated with ALPI had a larger increase in AOD750 (p=0.002) and TISA750 (p=0.006); a smaller increase in I-Area (p=0.004) and a decrease in I-Curv (p=0.001) after treatment compared with those eyes which received medical therapy. An optimal model consisting of age, gender, pretreatment and post-treatment pupil diameter, treatment modality and pretreatment I-Curv explained 53.2% of the variance in AOD750 change after treatment, with the treatment modality accounting for 35.0% and I-Curv accounting for 12.4% of the variability.

CONCLUSIONS

We observed a greater increase in angle width after ALPI compared with after medical treatment in eyes with APAC. Treatment modality and pretreatment I-Curv were the most significant predictors of angle width change after treatment.

Capsule wrinkling during capsulorhexis in patients with primary angle-closure glaucoma and cataract

PURPOSE

To evaluate the frequency of capsule wrinkling and associated factors during capsulorhexis in patients with primary angle-closure glaucoma (PACG) undergoing cataract surgery.

METHODS

This prospective study enrolled 91 eyes of 91 patients (26 eyes with PACG, 65 control eyes) who underwent cataract surgery. Capsule wrinkling during capsulorhexis was determined intraoperatively. The PACG group was evaluated for factors associated with capsule wrinkling such as intraocular pressure (IOP) on presentation, history of acute attacks, previous laser or trabeculectomy surgery, iris atrophy, peripheral anterior synechiae, and posterior synechiae.

RESULTS

The frequency of capsule wrinkling was higher in the PACG group (7/26, 26.9%) than in the control group (0/65, 0%) (P < 0.0001). Among the PACG patients, capsule wrinkling was associated with a higher IOP on presentation (54.71 ± 16.15 mmHg) than in patients without capsule wrinkling (32.95 ± 11.21 mmHg) (P = 0.001). Iris atrophy was significantly related to capsule wrinkling (P = 0.028), and the location of iris atrophy correlated with that of capsule wrinkling in 80% of cases (4/5).

CONCLUSIONS

Capsule wrinkling during capsulorhexis was a significant finding in some patients with cataract and PACG, especially when the IOP on presentation was high and iris atrophy was present.

Prevalence of glaucoma in rural Myanmar: the Meiktila Eye Study

AIM

To determine the prevalence of glaucoma in the Meiktila district of central, rural Myanmar.

METHODS

A cross-sectional, population-based survey of inhabitants > or =40 years of age from villages in Meiktila district, Myanmar, was performed; 2481 eligible participants were identified and 2076 participated in the study. The ophthalmic examination included Snellen visual acuity, slit-lamp examination, tonometry, gonioscopy, dilated stereoscopic fundus examination and full-threshold perimetry. Glaucoma was classified into clinical subtypes and categorised into three levels according to diagnostic evidence.

RESULTS

Glaucoma was diagnosed in 1997 (80.5%) participants. The prevalence of glaucoma of any category in at least one eye was 4.9% (95% CI 4.1 to 5.7; n = 101). The overall prevalence of primary angle-closure glaucoma (PACG) was 2.5% (95% CI 1.5 to 3.5) and of primary open-angle glaucoma (POAG) was 2.0% (95% CI 0.9 to 3.1). PACG accounted for 84% of all blindness due to glaucoma, with the majority due to acute angle-closure glaucoma (AACG).

CONCLUSION

The prevalence of glaucoma in the population aged > or =40 years in rural, central Myanmar was 4.9%. The ratio of PACG to POAG was approximately 1.25:1. PACG has a high visual morbidity and AACG is visually devastating in this community. Screening programmes should be directed at PACG, and further study of the underlying mechanisms of PACG is needed in this population.