Keraring Implantation Based on Alfonso Nomogram

Keratoconus (KC) is a bilateral asymmetric progressive corneal degenerative disease associated with corneal thinning and protrusion. The management of moderate progressive keratoconus involves halting its progression through corneal cross-linking as well as flattening of the ectatic steep cornea through the implantation of intrastromal corneal rings (ICR). Different nomograms were used to guide ophthalmic surgeons for the proper choice of ICR implantation to achieve the best results. The aim of the current study is to assess the visual, refractive and tomographic outcomes of Keraring implantation based on the Alfonso nomogram, in patients with keratoconus.

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This study is active but is not currently recruiting participants.

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Key information

Conditions

Keratoconic Subjects Corneal Diseases Eye Diseases Keratoconus

Age range

18 year–35 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

TIBA Eye Center

Asyut, Asyut Governorate, 71515, Egypt

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Patients aged between 18-35 years.
Patients diagnosed with progressive keratoconus.
Mean keratometry (Km) between 48-60 D.
Clear cornea

Exclusion criteria

Mild or advanced keratoconus
Corneal scarring.
Other corneal or ocular diseases.
Systemic diseases such as diabetes mellitus and autoimmune diseases.

Treatment and study plan

Intrastromal corneal ring segment implantation (ICRS)

Procedure

Patients with moderate progressive keratoconus underwent femtosecond laser-assisted intrastromal corneal ring (Keraring) implantation based on the Alfonso morphological surgical nomogram.

Primary outcomes

Corrected distance visual acuity

Time frame: 6 months

Corrected distance visual acuity is measured with Snellen's acuity chart and converted to logarithm of the minimum angle of resolution (logMAR) notation.
Spherical equivalent refraction

Time frame: 6 months

Spherical equivalent in diopters is measured with Topcon autorefractometer.
Maximum keratometry

Time frame: 6 months

The maximum keratometry in diopters is measured using pentacam.

Sponsors and collaborators

Lead sponsor

Assiut University

Other

Registry information

Official study title

Outcomes of Keraring Implantation in Patients With Keratoconus Guided by the Alfonso Morphological Surgical Nomogram

Important dates

Study start: 2025
Primary completion: 2026
Study completion: 2026
First posted: Apr 20, 2026
Registry last updated: Apr 20, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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