Changes in Anterior Segment Morphology and Predictors of Angle Widening after Laser Iridotomy in South Indian Eyes

Zebardast, Nazlee; Srinivasan, Kavitha; Palaniswamy, Krishnamurthy; Friedman, David S.; Nongpiur, Monisha E.; Aung, Tin; Quigley, Harry A.; Ramulu, Pradeep Y.; Venkatesh, Rengaraj

doi:10.1016/j.ophtha.2016.08.020

Cited by 48 publications

(28 citation statements)

References 34 publications

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“…,b; Zebardast et al. ). This further indicated that LPI may help to improve ACA characteristics via other means apart from reducing iris concavity.…”

Section: Discussionmentioning

confidence: 99%

Predicting the outcome of laser peripheral iridotomy for primary angle closure suspect eyes using anterior segment optical coherence tomography

Koh

Keshtkaran

Hernstadt

et al. 2018

Acta Ophthalmologica

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Purpose: Develop an algorithm to predict the success of laser peripheral iridotomy (LPI) in primary angle closure suspect (PACS), using pretreatment anterior segment optical coherence tomography (ASOCT) scans. Methods: A total of 69 eyes with PACS underwent LPI and time-domain ASOCT scans (temporal and nasal cuts) were performed before and after LPI. After LPI, success is defined as one or more angles changed from closed to open. All the pretreatment ASOCT scans were analysed using the Anterior Segment Analysis Program to derive anterior chamber angle (ACA) measurements. The measurements for each angle were ordered along with angle-independent measurements totalling to 42 measurements which serve as features for the prediction algorithm. Two masked glaucoma fellowship-trained ophthalmologists graded the pre-LPI ASOCT scans to determine whether LPI was likely to successful. Results: There were 42 (60.9%) eyes that fulfilled the criteria for success after LPI. Iris concavity, angle recess area (750 lm) and iris concavity ratio showed the highest predictive score and were selected using correlation-based subset selection method. These features were classified into two ('successful' and 'unsuccessful') categories using a Bayes classifier. The algorithm predicted the success of LPI with 79.28% cross validation accuracy, which was superior to the predictive accuracy of the ophthalmologists (kappa 0.497 and 0.636 respectively). Conclusion: Using pretreatment ASOCT scans, our algorithm was superior to ophthalmologists in predicting the success of LPI for PACS eyes. This novel algorithm could aid decision making in offering LPI as a prophylaxis for PACS.

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“…,b; Zebardast et al. ). This further indicated that LPI may help to improve ACA characteristics via other means apart from reducing iris concavity.…”

Section: Discussionmentioning

confidence: 99%

Predicting the outcome of laser peripheral iridotomy for primary angle closure suspect eyes using anterior segment optical coherence tomography

Koh

Keshtkaran

Hernstadt

et al. 2018

Acta Ophthalmologica

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“…The determination coefficient of the fitted line was 0.95, suggesting the linear model was able to express more than 95% of the variability in iris deformation. Iris deformation and variation in ACA were considered as the pathogenic mechanism of PACG [45]. Increased iris deformation could decrease AC depth and narrow ACA, resulting in a severe obstruction of AH outflow, which could cause high IOP in eye and induce acute attack of angle-closure glaucoma.…”

Section: Resultsmentioning

confidence: 99%

Computational Study on the Biomechanics of Pupil Block Phenomenon

Wang

Song

Liu

2019

BioMed Research International

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Pupil blocking force (PBF) can indicate the potential risk of pupil block (PB), which is considered as a main pathogenic factor of primary angle-closure glaucoma (PACG). However, the effect of PB on the PBF under different pupil diameters and iris-lens channel (ILC) distance was unknown. Besides, a simple and practical method to assess PBF has not been reported yet. In this study, 21 finite element models of eyes with various pupil diameters (2.4 mm–2.6 mm) and ILC (2 μm–20 μm) were constructed and were conducted to simulate aqueous humor flow by fluid-solid coupling numerical simulation. PBF in each model was calculated based on the numerical simulation results and was fitted using response surface methodology. The results demonstrated that ILC distance had a more significant effect than pupil diameter on PBF. With the decrease of ILC distance, the PBF increased exponentially. When the reduced distance was lower than 5 μm, the PBF exploded quickly, resulting in a high risk of iris bomb. The PBF also varied with pupil diameter, especially under the condition of narrow ILC. Both ILC distance and pupil diameter could explain more than 97% variation in PBF, and a second-order empirical model has been developed to be a good predictor of PBF. Based on the linear relationship between anterior chamber deformation and PBF, a threshold value of PBF was given to guide clinical decisions. This study could be used to investigate PACG pathological correlation and its pathogenesis, so as to provide a reference value for clinical diagnosis of PACG.

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“…16 Greatest effect of Laser Peripheral Iridotomy is seen in eyes with greatest baseline pupil block. 17 Laser trabeculoplasty has role in narrow angle as well once angle is opened by laser iridotomy or Iridoplasty. Its efficacy is proved in Laser Glaucoma study, 18 Early manifest Glaucoma trial 19 and Advanced glaucoma intervention study.…”

Section: Discussionmentioning

confidence: 99%

Role of Anterior Segment OCT in the Management of Primary Narrow Angle Disease

Muid¹,

Farooq²

2020

pak J Ophthalmol

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Purpose: To highlight the role of anterior segment OCT, in complementing gonioscopic findings in the management of angle closure glaucoma. Study Design: Descriptive observational case series. Study Place and Duration: Study was conducted at Eye department of Shifa International Hospital, from January 2019 to March 2019. Methods: After taking informed consent from the patients, the study was conducted at Shifa International Hospital Islamabad. Patients were selected by convenient sampling technique. Patients were diagnosed on the basis of history and clinical examination. Patients with angle closure on Gonioscopy were included in this series. Detailed ocular examination including visual acuity for distance and near, tonometry, Gonioscopy and anterior segment OCT were performed. Data was collected and presented as case series. Results: The median age 57 years with 50% more than 60 years and 50% less than 60 years of age. Presenting IOP was less than 21 mmHg in 50% and higher in remaining 50%. On examination 37.5% were categorized as PACS, 12.5% having PAC and 50% as PACG. After definitive treatment 12.5% still needed medical treatment to prevent progression in PACG and none in PACS and PAC. Conclusion: In narrow angle disease, treatment is designed not only to control intraocular pressure (IOP) but also to keep angle open as much as possible. Appositional closure or peripheral anterior synechiae (PAS) can damage the trabecluar meshwork. Iridoplasty, peripheral Iridotomy (PI) and early lens extraction can defer the need for filtration procedure if done well in time. Key Words: OCT anterior segment, Narrow angle, Optic nerve head.

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Changes in Anterior Segment Morphology and Predictors of Angle Widening after Laser Iridotomy in South Indian Eyes

Cited by 48 publications

References 34 publications

Predicting the outcome of laser peripheral iridotomy for primary angle closure suspect eyes using anterior segment optical coherence tomography

Predicting the outcome of laser peripheral iridotomy for primary angle closure suspect eyes using anterior segment optical coherence tomography

Computational Study on the Biomechanics of Pupil Block Phenomenon

Role of Anterior Segment OCT in the Management of Primary Narrow Angle Disease

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