Photorefractive Keratectomy for Severe Anisometropia and Isoametropia Associated With Amblyopia

• ClinicalTrials.gov Identifier: NCT03610997
• Recruitment Status: Active, not recruiting
• First Posted: August 2, 2018
• Last Update Posted: January 19, 2021
• Sponsor: Baylor College of Medicine
• Information provided by (Responsible Party): Evelyn, Baylor College of Medicine

Study Description

Brief Summary:

Photorefractive keratectomy (PRK) with excimer laser has been used successfully to treat myopia, hyperopia, and astigmatism in adults for over 30 years. Children with high refractive errors that go untreated will develop severe amblyopia. PRK can normalize high refractive errors and potentially improve the amblyopia in affected children. The purpose of this study is to investigate whether children with high anisometropia or isoametropia with amblyopia that are nonresponsive to standard therapy and receive PRK develop better longterm visual acuity.

Condition or disease	Intervention/treatment	Phase
Anisometropia; Hyperopia; High Myopia; Amblyopia Isometropic; Amblyopia Bilateral; High Astigmatism	Procedure: Photorefractive keratectomy	Not Applicable

Detailed Description:

Anisometropia is a condition in which one eye has a significantly different refractive error from the other and commonly leads to the development of refractive amblyopia in the affected eye. High isoametropia is the condition in which both eyes have high refractive error and commonly leads to bilateral refractive amblyopia if untreated. Amblyopia is the condition in which vision does not develop fully in the brain due to disuse or misuse of one or both eyes. Typically, in high anisometropia, a contact lens in the eye with the stronger refractive error and/or glasses must be used to correct the refractive error. Commonly, infants and children with this condition refuse to wear the contact lens or glasses because the other eye sees normally. There are other problems in treating high anisometropia with glasses. One is aniseikonia, the condition of image size disparity between the two eyes. This causes difficulty for the brain of the affected person to fuse the images from the two eyes because the image from one eye is much larger than that from the other eye. This results in asthenopia (eye fatigue) and sometimes even diplopia. If the anisometropia is severe, significant amblyopia will result in the eye with the stronger refractive error and, if not treated at an early age, permanent and potentially severe vision loss will result.

In high isoametropia, contact lenses or glasses must likewise be used in order for normal vision to develop. Most children with isoametropia will wear glasses well because they cannot see well without them. By contrast, children with developmental delays, chromosomal abnormalities, autism, or attention deficit hyperactivity disorder and high isoametropia very commonly will not wear the needed refractive correction due to strong tactile aversion to anything touching the face or head. If the refractive error is high, significant bilateral (isoametropic) amblyopia will result and, if not treated at an early age, permanent and potentially severe vision loss will result.

PRK can normalize high refractive errors and potentially improve the amblyopia in affected children. The purpose of this study is to investigate whether children with high anisometropia or isoametropia with amblyopia that are nonresponsive to standard therapy and receive PRK develop better longterm visual acuity. Secondary outcomes are stability of refractive correction, and corneal health.

Study Design

• Study Type: Interventional (Clinical Trial)
• Estimated Enrollment: 200 participants
• Allocation: N/A
• Intervention Model: Single Group Assignment
• Intervention Model Description: Photorefractive Keratectomy
• Masking: None (Open Label)
• Primary Purpose: Treatment
• Official Title: Photorefractive Keratectomy for Anisometropic and Isoametropic Amblyopia in Children Refractory to Conventional Treatment
• Actual Study Start Date: January 1, 2001
• Estimated Primary Completion Date: August 1, 2028
• Estimated Study Completion Date: October 1, 2028

Arms and Interventions

Arm	Intervention/treatment
Photorefractive keratectomy; The children will undergo PRK in the affected eye(s) using previously derived formulas for PRK.	Procedure: Photorefractive keratectomy

Outcome Measures

Primary Outcome Measures :

1. Visual acuity [ Time Frame: 10 years ]
   Snellen equivalent

Secondary Outcome Measures :

1. Refractive error [ Time Frame: 10 years ]
   cycloplegic refraction
2. Corneal clarity [ Time Frame: 10 years ]
   slit lamp exam

Eligibility Criteria

• Ages Eligible for Study: 2 Years to 17 Years (Child)
• Sexes Eligible for Study: All
• Accepts Healthy Volunteers: No

Criteria

Inclusion Criteria:.

• Children aged 2 to 17 with significant anisometropia or isoametropia and amblyopia that have failed traditional treatment for at least 6 months.
• Anisometropic group:
• The anisometropia must be at least 3.00 diopters.
• The amblyopic eye best corrected visual acuity must be at least 2 lines worse than the fellow eye in verbal children
• Isoametropic group
• Myopia must be at least -4.00 diopters in both eyes
• Hyperopia must be at least 4.00 diopters in both eyes
• Astigmatism must be at least 2.50 diopters in both eyes.

Exclusion Criteria:

• History of significant corneal abnormality that, in the investigator's opinion, may limit visual rehabilitation.
• History of known collagen disorder
• History of known corneal ectasia
• History of previous herpes simplex keratitis
• Corneal thickness of less than 450u

Contacts and Locations

Locations

United States, Texas

Texas Children's Hospital

Houston, Texas, United States, 77030

Sponsors and Collaborators

Baylor College of Medicine

Investigators

• Principal Investigator: Evelyn Paysse, MD; Baylor College of Medicine

More Information

• Responsible Party: Evelyn, Professor of Ophthalmology and Pediatrics, Baylor College of Medicine
• ClinicalTrials.gov Identifier: NCT03610997
• Other Study ID Numbers: H-6604
• First Posted: August 2, 2018
• Last Update Posted: January 19, 2021
• Last Verified: January 2021

Individual Participant Data (IPD) Sharing Statement:

• Plan to Share IPD: No

• Product Manufactured in and Exported from the U.S.: No

Additional relevant MeSH terms:

Amblyopia; Astigmatism; Hyperopia; Anisometropia; Refractive Errors; Eye Diseases; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Vision Disorders; Sensation Disorders; Neurologic Manifestations