Assessment of anterior chamber angle changes after phacoemulsification with swept-source OCT

Evaluation of changes of anterior segment parameters in patients with pseudoexfoliation syndrome after cataract surgery using anterior segment optical coherence tomography

The aim of the study was to compare the anterior segment parameters after cataract surgery in pseudoexfoliation syndrome (PEX) and control eyes. We conducted a prospective comparative study of 36 eyes (PEX group), 16 eyes (PEXG group) and 46 eyes (control group) of 98 patients after phacoemulsification with intraocular lens implantation. Before surgery, 1 week, 1 month and 3 months postoperatively, anterior chamber parameters were evaluated by swept source anterior segment optical coherence tomography (AS-OCT). Anterior chamber depth (ACD), angle opening distance (AOD500/750), trabecular-iris space area (TISA500/750), trabecular-iris angle (TIA500/750) and lens vault (LV) were assessed at each study visit. Preoperatively, ACD, AOD500/750 and TISA500/750 were significantly smaller, while LV was significantly greater in PEX and PEXG eyes than in controls. 3 months postoperatively all irido-corneal parameters and ACD were significantly greater in all study groups without intergroup differences. ACD and LV significantly increased in PEX group between 1 and 3 months after surgery while being stable in control group. Relative increases in ACD, AOD500, TISA750, TIA500/750 were significantly higher in PEX and PEXG groups than in controls. Our study finds that ACD and iridocorneal parameters in AS-OCT demonstrated significantly greater relative increases 3 months after phacoemulsification in PEX and PEXG groups than in control eyes. Significantly greater deepening of anterior chamber and opening of the irido-corneal angle may be a reason for different refractive outcomes and IOP control in patients with PEX and PEXG after routine cataract surgery.

SeqCorr-EUNet: A sequence correction dual-flow network for segmentation and quantification of anterior segment OCT image

The accurate segmentation of AS-OCT images is a prerequisite for the morphological details analysis of anterior segment structure and the extraction of clinical biological parameters, which play an essential role in the diagnosis, evaluation, and preoperative prognosis management of many ophthalmic diseases. Manually marking the boundaries of the anterior segment tissue is time-consuming and error-prone, with inherent speckle noise, various artifacts, and some low-quality scanned images further increasing the difficulty of the segmentation task. In this work, we propose a novel model called SeqCorr-EUNet with a dual-flow architecture based on convolutional gated recursive sequence correction for semantic segmentation and quantification of AS-OCT images. An EfficientNet encoder is employed to enhance the intra-slice features extraction ability of semantic segmentation flow. The sequence correction flow based on ConvGRU is introduced to extract inter-slice features from consecutive adjacent slices. Spatio-temporal information is fused to correct the morphological details of pre-segmentation results. And the channel attention gate is inserted into the skip-connection between encoder and decoder to enrich the contextual information and suppress the noise of irrelevant regions. Based on the segmentation results of the anterior segment structures, we achieved automatic extraction of essential clinical parameters, 3D reconstruction of the anterior chamber structure, and measurement of anterior chamber volume. The proposed SeqCorr-EUNet has been evaluated on the public AS-OCT dataset. The experimental results show that our method is competitive compared with the existing methods and significantly improves the segmentation and quantification performance of low-quality imaging structures in AS-OCT images.

Axial length and anterior chamber indices in elderly population: Tehran Geriatric Eye Study

AIM

To determine the normative distribution of axial length (AL), anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), and some of their associated factors in subjects aged 60 and over.

METHODS

In this cross-sectional study, 160 clusters were sampled using multi-stage cluster sampling in Tehran, Iran. After a preliminary interview, the participants underwent optometric examinations including visual acuity and refraction measurement followed by slit lamp biomicroscopy. Finally, ocular imaging was done using the Pentacam AXL to measure AL, ACD, ACV, and ACA.

RESULTS

A total of 4519 eyes of 2436 participants were evaluated, of whom 58.0% (n=1412) were female. The mean age of the subjects was 67.32±6.05y (range: 60-95y). The mean AL, ACD, ACV, and ACA was 23.22 mm (23.18-23.27 mm), 2.61 mm (2.59-2.62 mm), 126.56 mm3 (125.08-128.04 mm3), and 30.61° (30.3°-30.92°), respectively. In the multivariable model, after adjusting for the effect of both eyes, the longest and shortest AL was seen in myopic and hyperopic subjects, respectively. AL, ACD, ACV and ACA were significantly larger in men compared to women (P<0.001). Except ACA, other evaluated parameters showed an inverse correlation with age (P<0.001), however, this correlation was insignificant for AL (P=0.623).

CONCLUSION

Normative value of AL, and other biometric parameters are specific for each ethnicity, age and sex group. Any alteration in these parameters and their effect on refraction should be considered in this age group, especially in case of cataract surgery.

Comparison of changes in retinal nerve fiber layer thickness and intraocular pressure between glaucoma and non-glaucoma patients after phacoemulsification

Objective

To compare the changes in Retinal Nerve Fiber Layer (RNFL) thickness and Intraocular Pressure (IOP) after phacoemulsification in patients with glaucoma versus without glaucoma.

Methods

This was a quasi-experimental study, done at Lahore General Hospital, from January 2021 to December 2021. Patients with senile cataract were divided into two groups. One group included 40 patients, with ≥40 years of age and diagnosed with primary open angle glaucoma compared with a second group of 40 age-matched controls without glaucoma, undergoing phacoemulsification and Intraocular Lens Implantation (IOL). Goldman Applanation Tonometer (GAT) and Spectral Domain Optical Coherence Tomography (SD-OCT) were used to record IOP and RNFL thickness, before surgery, at one week and one month after surgery. The results were compared with baseline readings and also between the two groups.

Results

A total of 80 patients were included in the study. Mean age was 60.3±7.9 years with male to female ratio of 1:1. Mean change in RNFL thickness in glaucomatous eyes group and non-glaucomatous Eyes group from pre-operative baseline was 11.33±4.30μm and 4.08±2.59μm respectively after one month (p-value<0.001). Difference of mean change in RNFL thickness from baseline was statistically significant between both groups (p< 0.001). Difference of mean change in IOP from baseline at four weeks was statistically significant in the individual groups but between both groups was statistically insignificant (p= 0.234).

Conclusion

Phacoemulsification results in increase in RNFL thickness and decrease in IOP, which are good prognostic factors in control of glaucoma. However, a mean change of IOP of 1mmHg in glaucoma patient does not affect management of glaucoma.

CO2 Laser-Assisted Sclerectomy Surgery Alone or Combined with Phacoemulsification in Primary Open-Angle Glaucoma: Comparison of 1-Year Outcomes

INTRODUCTION

To compare 1-year outcomes of CO2 laser-assisted sclerectomy surgery (CLASS) alone or combined with phacoemulsification (CLASS + Phaco) in eyes with primary open-angle glaucoma (POAG).

METHODS

This was a prospective, comparative, case series study. A total of 46 eyes with POAG underwent CLASS or CLASS + Phaco were followed up for 1 year. The primary outcomes included changes in intraocular pressure (IOP), medication and best corrected visual acuity (BCVA). The secondary outcomes were success rate, functional bleb, postoperative laser intervention and complications.

RESULTS

CLASS alone resulted in a greater IOP reduction compared with CLASS + Phaco. BCVA improved remarkably in CLASS + Phaco group, but there was no difference in BCVA before and after CLASS. The number of antiglaucoma medications significantly decreased at 12 months postoperatively in both groups. Functional blebs were more commonly seen in the CLASS than combination group. The overall success rate was higher in the CLASS than CLASS + Phaco group at 1 year after surgery. The incidence of peripheral anterior synechiae (PAS) in CLASS + Phaco group was significantly lower than that of CLASS alone.

CONCLUSION

CLASS alone achieved a greater IOP reduction, more common functional bleb formation and a higher success rate compared to CLASS combined with Phaco, while combination surgery yielded a better BCVA improvement and a lower PAS incidence than CLASS alone. Both surgical strategies have favorable safety and efficacy among POAG patients. Combined surgery could be a viable option for patients with co-existing POAG and cataract.

Reducing speckle in anterior segment optical coherence tomography images based on a convolutional neural network

Speckle noise is ubiquitous in the optical coherence tomography (OCT) image of the anterior segment, which greatly affects the image quality and destroys the relevant structural information. In order to reduce the influence of speckle noise in OCT images, a denoising algorithm based on a convolutional neural network is proposed in this paper. Unlike traditional algorithms that directly obtain denoised images, the algorithm model proposed in this paper learns the speckle noise distribution through the constructed trainable OCT dataset and indirectly obtains the denoised result image. In order to verify the performance of the model, we compare the denoising results of the algorithm proposed in this paper with several state-of-the-art algorithms from three perspectives: qualitative evaluation from the subjective visual perspective, quantitative evaluation from objective parameter indicators, and running time. The experimental results show that the proposed algorithm has a good denoising effect on different OCT images of the anterior segment and has good generalization ability. Besides, it retains the relevant details and texture information in the image, and it has strong edge preserving ability. The image of OCT speckle removal can be obtained within 0.4 s, which meets the time limit requirement of clinical application.