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CompletedNCT05748847Updated Oct 31, 2024

Pocket Versus Tunnel ICRS for Treatment of Keratoconus

An interventional study of Intrastromal corneal ring segment implantation (Pocket) and Intrastromal corneal ring segment implantation (Tunnel) in Keratoconus, sponsored by Assiut University. Completed at 1 site in Egypt. Open to participants aged 18 Years to 35 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2024-10-31.

Sponsored by Assiut University · Not applicable, Interventional, and Treatment

From the registry’s dates

  • Registered 3 years 8 months after the study started (first participant enrolled Jun 2019, registered Feb 2023).
Phase
Not applicable
Study type
Interventional
Enrollment
74
Allocation
Randomized
Ages
18 Years to 35 Years
Sex
All
01

Study summary

Keratoconus is a corneal degenerative disease associated with loss of best-corrected visual acuity. The use of intrastromal corneal ring segment implants is indicated to regularize the cornea and to reduce aberrations.

Read the detailed description

Keratoconus is a corneal degenerative disease characterized by corneal thinning and subsequent development of irregular astigmatism, diminution of vision and loss of best-corrected visual acuity.

Management of keratoconus includes halting disease progression through a corneal strengthening procedure called corneal collagen cross-linking (CXL) which usually results in stabilizing the condition but with no improvement in visual acuity or quality. Intrastromal corneal ring segment (ICRS) implantation is a well-established procedure for the management of moderate keratoconus with a corneal flattening effect that is associated with improvement of visual acuity and reduction of optical aberrations.

The aim of the study is to evaluate and compare the visual, refractive and topographic outcomes of two different femtosecond laser assisted surgical techniques to create a corneal stromal pocket or a tunnel for implantation of ICRS for the management of central keratoconus

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Conditions studied

  • Keratoconus

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Keywords

  • Keratoconus
  • Femtosecond laser-assisted ICRS
  • Central keratoconus
  • KeraRing
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In context

Keratoconus

312 studies on the registry are indexed under Keratoconus; 56 are open to participants now.

This study's enrollment of 74 is above the median of 40 across 205 interventional studies indexed under Keratoconus.

Browse Keratoconus studies →

Lead sponsor

Assiut University is the lead sponsor of 5,050 studies on the registry; 2,174 are open to participants now.

Of its 14 completed or terminated interventional studies of FDA-regulated products, 0 (0%) have results posted.

Counted across the registry records on this site, refreshed daily.

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Who can participate

Ages eligible
18 Years to 35 Years
Sexes eligible
All
Accepts healthy volunteers
Yes

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  1. Patients with progressive keratoconus with maximum keratometry (Kmax) between 50-65 diopters
  2. Central keratoconus (Keratoconus with steepest corneal point within the central 3 mm zone).
  3. Clear corneal with a minimum pachymetry of 400 μm.

Exclusion criteria

Exclusion Criteria:

  1. Corneal scars
  2. Patients with advanced keratoconus with Kmax > 65 diopters.
  3. Non-central keratoconus (para-central or peripheral keratoconus with steepest corneal point outside the central 3 mm zone).
  4. Previous corneal cross-linking and/or ocular surgery.
  5. Systemic diseases such as diabetes mellitus and autoimmune diseases
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Study design

Phase
Not applicable
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Single (Participant)
Enrollment
74 participants (actual)

Study arms

  • Active comparator
    Pocket ICRS

    Patients in this group underwent 360-degree MyoRing implantation through a femtosecond laser-assisted corneal pocket creation for the management of their central keratoconus.

    Procedure: Intrastromal corneal ring segment implantation (Pocket)

  • Active comparator
    Tunnel ICRS

    Patients in this group are underwent 340-degree KeraRing implantation through a femtosecond laser-assisted corneal tunnel creation for the management of their central keratoconus.

    Procedure: Intrastromal corneal ring segment implantation (Tunnel)

Interventions

  • ProcedureIntrastromal corneal ring segment implantation (Pocket)

    Patients in this group are planned to undergo ICRS implantation through a femtosecond laser-assisted pocket creation. The device creates an intrastromal corneal pocket of 8-mm diameter and a depth of nearly 80% of the corneal thickness at the thinnest location with a superior tunnel incision at 90° of 5-mm width.

  • ProcedureIntrastromal corneal ring segment implantation (Tunnel)

    Patients in this group are planned to undergo ICRS implantation through a femtosecond laser-assisted tunnel creation. The device creates an intrastromal tunnel with a depth of nearly 80% of the corneal thickness at the site of implantation. The tunnel inner and outer diameters are at 5 and 6 mm from the corneal center, respectively with the incision located at the steepest keratometry axis.

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What researchers measure

Primary outcomes

  1. Complications

    Postoperative complications following intrastromal corneal ring segment implantation.

    Time frame: 12 months

  2. Postoperative keratometry

    Postoperative keratometry as measured by Scheimpflug imaging Pentacam

    Time frame: 12 months

  3. Postoperative Refraction

    Spherical equivalent refraction measured by Topcon Auto-Keratorefractometer

    Time frame: 12 months

  4. Corrected distance visual acuity (CDVA)

    Corrected distance visual acuity measurement using Snellen's Acuity Chart expressed as logMAR notation

    Time frame: 12 months

  5. Uncorrected distance visual acuity (UDVA)

    Uncorrected distance visual acuity measurement using Snellen's Acuity Chart expressed as logMAR notation

    Time frame: 12 months

07

Study locations

1 site
  • Tiba Eye Center
    Asyut, Asyut Governorate 71516, Egypt
08

References and documents

Publications

  • Izquierdo L Jr, Rodriguez AM, Sarquis RA, Altamirano D, Henriquez MA. Intracorneal circular ring implant with femtosecond laser: Pocket versus tunnel. Eur J Ophthalmol. 2022 Jan;32(1):176-182. doi: 10.1177/1120672121994729. Epub 2021 Feb 12. PubMed 33579160 ↗
  • Abdel-Radi M, Anwar M, Mostafa MM. Complications and Outcomes of Femtosecond Laser-Assisted Corneal Pocket Implantation of 360-Degree MyoRing(R) Versus Corneal Tunnel Implantation of 340-Degree Keraring(R) for the Management of Central Keratoconus. Curr Eye Res. 2026 Mar;51(3):231-239. doi: 10.1080/02713683.2025.2587890. Epub 2025 Nov 20. PubMed 41263332 ↗

Individual participant data

Plan to share: No

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Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Oct 31, 2024, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT05748847
Lead sponsor
Assiut University
Responsible party
Mahmoud Abdel-Radi (Principal Investigator, Assiut University) — Principal investigator
First posted
Mar 1, 2023
Start date
Jun 1, 2019
Primary completion
Apr 15, 2023
Completion
Apr 15, 2023
Last update
Oct 31, 2024

Study contacts

Mahmoud Abdel-Radi, MD
principal investigator · Assiut University

Oversight

Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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This study is completed, as verified in Oct 2024. You cannot join it, but the record below documents what was studied.

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