Posterior Capsulotomy in Cataract Complicated With Primary Posterior Capsule Opacification.

Overview

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).

Full Title of Study: “Phacoemulsification Combined With Posterior Capsulotomy in Cataract Complicated With Primary Posterior Capsule Opacification: a Randomized Controlled Trial”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Treatment
    • Masking: Single (Outcomes Assessor)
  • Study Primary Completion Date: February 2019

Detailed Description

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).

Interventions

  • Procedure: posterior capsulotomy
    • 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.
  • Procedure: laser capsulotomy
    • 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.

Arms, Groups and Cohorts

  • Experimental: posterior capsulotomy
    • Primary posterior capsulotomy will be performed to remove the primary posterior capsule opacification after posterior capsule polishing during phacoemulsification.
  • Active Comparator: Nd:YAG laser capsulotomy
    • Nd:YAG laser capsulotomy will be performed 1 month postoperative to remove the primary posterior capsule opacification.

Clinical Trial Outcome Measures

Primary Measures

  • LogMAR visual acuity 1 month postoperatively
    • Time Frame: 1 month
    • Best corrected visual acuity (LogMAR) will be measured 1 month postoperatively.

Secondary Measures

  • Dysfunctional lens index (DLI)
    • Time Frame: 3 months
    • 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.
  • Internal higher order aberration (HOAs)
    • Time Frame: 3 months
    • TInternal higher order aberration (HOAs) in micrometer can quantify the intraocular optical quality and will be measured by iTrace aberrometer.
  • Object scatter index (OSI)
    • Time Frame: 3 months
    • 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).
  • Modulation transfer function cut off (MTF cut off)
    • Time Frame: 3 months
    • 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.
  • Strehl ratio (SR)
    • Time Frame: 3 months
    • 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.
  • Predicted visual acuity (PVA) with contrasts of 100%, 20% and 10%
    • Time Frame: 3 months
    • 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.
  • Rate of ocular hypertension
    • Time Frame: 3 months
    • Diagnosis of ocular hypertension is based on IOP greater than 21 mm Hg and the rate of ocular hypertension is calculated.
  • Rate of ocular macular edema
    • Time Frame: 3 months
    • The central macular thickness in micrometer is measured by optical coherence tomography (OCT) and the rate of ocular macular edema is calculated.
  • Rate of retinal detachment
    • Time Frame: 3 months
    • Retinal detachment following surgical or laser posterior capsulotomy is documented and the rate of Retinal detachment is calculated.
  • Rate of intraocular lens damage
    • Time Frame: 3 months
    • The rate of intraocular lens damage by Nd:YAG laser is documented.
  • Visual-functioning index 7 score
    • Time Frame: 3 months
    • 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

Participating in This Clinical Trial

Inclusion Criteria

1. Cataract patients with primary posterior capsular opacification, which involves the central posterior capsular and interferes with visual axis; 2. Aged 18 years or over; 3. With best corrected visual acuity (BCVA) less than 0.3. Exclusion Criteria:

1. History of other eye disease that contributes to visual impairment, including keratopathy, uveitis, glaucoma, retinopathy, ocular trauma, or intraocular surgery. 2. Cases with operative complications, including anterior or posterior capsular rupture, lens suspensory ligament rupture, the falling of lens nucleus into vitreous cavity. 3. Unwillingness to participate in the study.

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • Zhongshan Ophthalmic Center, Sun Yat-sen University
  • Provider of Information About this Clinical Study
    • Principal Investigator: Yizhi Liu, Clinical Professor,director of Zhongshan Ophthalmic Center – Zhongshan Ophthalmic Center, Sun Yat-sen University
  • Overall Official(s)
    • Yizhi Liu, PhD, Principal Investigator, Zhongshan Ophthamic Center,Sun Yet-san University
  • Overall Contact(s)
    • Xuhua Tan, PhD, +8613926019722, doctxh@163.com

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