Posterior Capsulotomy in Cataract Complicated With Primary Posterior Capsule Opacification.

Study Overview
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Brief Summary
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This is a two-arm, parallel group, open-label, randomized controlled trial to compare the visual acuity, visual quality, operative complications and the satisfaction of patients between primary posterior capsulorhexis group and laser capsulotomy group of cataract patients combined with primary posterior capsular opacification (PPCO).

Detailed Description
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Primary posterior capsular opacification (PPCO) refers to the posterior capsule opacification which cannot be removed by polishing or vacuuming during cataract surgery. The surgeon may have to decide on primary posterior capsulorhexis or early neodymium-doped yttrium aluminum garnet (Nd:YAG) laser capsulotomy in these cases. The aim of this study is to compare the visual acuity, visual quality, operative complications and the satisfaction of patients between primary posterior capsulorhexis group and laser capsulotomy group of cataract patients combined with primary posterior capsular opacification (PPCO).

Official Title
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Phacoemulsification Combined With Posterior Capsulotomy in Cataract Complicated With Primary Posterior Capsule Opacification: a Randomized Controlled Trial

Conditions
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Posterior Capsule Opacification, Cataract

Intervention / Treatment
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* Procedure: posterior capsulotomy
* Procedure: laser capsulotomy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Cataract patients with primary posterior capsular opacification, which involves the central posterior capsular and interferes with visual axis; Aged 18 years or over; With best corrected visual acuity (BCVA) less than 0.3. Exclusion Criteria: History of other eye disease that contributes to visual impairment, including keratopathy, uveitis, glaucoma, retinopathy, ocular trauma, or intraocular surgery. Cases with operative complications, including anterior or posterior capsular rupture, lens suspensory ligament rupture, the falling of lens nucleus into vitreous cavity. Unwillingness to participate in the study.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: posterior capsulotomy<br>Primary posterior capsulotomy will be performed to remove the primary posterior capsule opacification after posterior capsule polishing during phacoemulsification. | Procedure: posterior capsulotomy<br>* After phacoemulsification with intraocular lens implantation, primary posterior capsulotomy will be performed to remove the primary posterior capsule opacification after posterior capsule polishing. A limited anterior vitrectomy will be performed if the anterior hyaloid surface is broken.<br>|
| Active Comparator: Nd:YAG laser capsulotomy<br>Nd:YAG laser capsulotomy will be performed 1 month postoperative to remove the primary posterior capsule opacification. | Procedure: laser capsulotomy<br>* A routine phacoemulsification with intraocular lens implantation is performed. Then the Nd:YAG laser capsulotomy will be performed 1 month postoperative to remove the primary posterior capsule opacification.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| LogMAR visual acuity 1 month postoperatively | Best corrected visual acuity (LogMAR) will be measured 1 month postoperatively. | 1 month | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Dysfunctional lens index (DLI) | The dysfunctional lens index (DLI) is an objective lens performance metric derived from internal higher order aberrations (HOAs), pupil size, and contrast sensitivity data. DLI is a score ranged from 0 to 10. DLI will be measured by iTrace aberrometer. | 3 months | 
| Internal higher order aberration (HOAs) | TInternal higher order aberration (HOAs) in micrometer can quantify the intraocular optical quality and will be measured by iTrace aberrometer. | 3 months | 
| Object scatter index (OSI) | Object scatter index (OSI) is a ratio of 12 and 20 points from the perspective of the annular region of the light and the central 1 point perspective peak. OSI can objectively evaluate the amount of intraocular scattering and is an important index of optical quality. OSI is a score ranged from 0 to 10 and will be measured by Optical Quality Analysis System (OQAS). | 3 months | 
| Modulation transfer function cut off (MTF cut off) | Modulation transfer function cut off (MTF cut off) relates directly to retinal image quality and is a useful indicator of visual performance in cataract eyes. MTF cut off will be measured by OQAS. | 3 months | 
| Strehl ratio (SR) | Strehl ratio (SR) is computed as the ratio between the areas under the MTF curve of the measured eye and that of the aberration-free eye, and therefore it provides more global information on the optical quality. SR is a score ranged from 0 to 1 and will be measured by OQAS. | 3 months | 
| Predicted visual acuity (PVA) with contrasts of 100%, 20% and 10% | Predicted visual acuity (PVA) with contrasts of 100%, 20% and 10% correspond to three specific frequencies of the MTF that describe the eye's optical quality for the contrast values mentioned. In general, PVAs higher than 1 are associated to very high retinal image quality. PVA will be measured by OQAS. | 3 months | 
| Rate of ocular hypertension | Diagnosis of ocular hypertension is based on IOP greater than 21 mm Hg and the rate of ocular hypertension is calculated. | 3 months | 
| Rate of ocular macular edema | The central macular thickness in micrometer is measured by optical coherence tomography (OCT) and the rate of ocular macular edema is calculated. | 3 months | 
| Rate of retinal detachment | Retinal detachment following surgical or laser posterior capsulotomy is documented and the rate of Retinal detachment is calculated. | 3 months | 
| Rate of intraocular lens damage | The rate of intraocular lens damage by Nd:YAG laser is documented. | 3 months | 
| Visual-functioning index 7 score | Subjective satisfaction of patients is investigated by visual-functioning index 7 (VF-7) questionnaire. The VF-7 questionnaire comprises 7 questions for performing daily-life activities (1= a great deal of difficulty; 2= a moderate amount difficulty; 3= a little difficulty; 4= no difficulty). The VF-7 score is the average score of these 7 activities multiplied by 25, to give a final score between 0 and 100. nighttime driving; reading small print; watching television; seeing steps, stairs, or curbs; reading traffic, street, or store signs; cooking; doing fine handwork | 3 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Nd:YAG laser capsulotomy, phacoemulsification, cataract, primary posterior capsule opacification, posterior capsulotomy, randomized controlled trial