How is Photrexa Administered?: A Comprehensive Guide

October 7, 2025 •

2 min read

Over 95% of commercially insured patients now have access to FDA-approved corneal cross-linking using Photrexa and the KXL system. In this outpatient procedure, a clinician administers the prescription riboflavin eye drops, or Photrexa, in a specific sequence to treat progressive keratoconus or corneal ectasia.

Quick Summary

Photrexa is a photosensitizer riboflavin eye drop, administered topically in a multi-step, in-office procedure called corneal collagen cross-linking, which requires prior epithelial removal and subsequent UVA light exposure.

Key Points

Topical Administration: Photrexa is administered as eye drops, not as an injection, directly onto the surface of the eye.
Epi-Off Technique: The outermost layer of the cornea, the epithelium, must be removed to allow the riboflavin solution to penetrate the corneal tissue effectively.
Soaking Phase: The process involves an initial soaking period where Photrexa Viscous drops are applied.
Corneal Thickness Check: Corneal thickness is checked using ultrasound pachymetry to ensure it meets the minimum safety threshold before UVA irradiation.
Irradiation Phase: The soaked cornea is exposed to UVA light, with continued instillation of Photrexa Viscous drops throughout.
Hypotonic Photrexa: A specific, hypotonic formulation of Photrexa is used to swell the cornea if its thickness is initially insufficient.
Post-Procedure Care: Patients must wear a bandage contact lens and avoid rubbing their eyes for several days after the procedure.

What is Photrexa?

Photrexa, a trade name for a riboflavin 5'-phosphate ophthalmic solution, is a photosensitizer used in corneal collagen cross-linking (CXL). Riboflavin, or Vitamin B2, absorbs ultraviolet (UVA) light to create reactive oxygen species, strengthening the cornea by forming cross-links between collagen fibers. This procedure treats progressive keratoconus and corneal ectasia, aiming to slow disease progression and preserve vision. Photrexa administration is a key part of this FDA-approved procedure using the KXL system.

The Step-by-Step Photrexa Administration Process

Photrexa is administered in an "epi-off" procedure where the corneal epithelium is removed to improve riboflavin penetration. The procedure takes about 60 to 90 minutes. For a detailed step-by-step guide to the administration process, refer to {Link: TexasEyes.com https://www.texaseyes.com/corneal-cross-linking}. This includes information on:

Pre-Procedure Preparation

Corneal Epithelium Removal

Riboflavin Soaking Phase

Saturation Check and Corneal Thickness Assessment

UVA Light Irradiation and Continued Drop Application

Post-Procedure

Photrexa and Photrexa Viscous: A Comparison

Two Photrexa formulations are used depending on corneal thickness. For a comprehensive comparison of the two formulations, refer to {Link: TexasEyes.com https://www.texaseyes.com/corneal-cross-linking}. The comparison highlights:


Feature	Photrexa Viscous	Photrexa (Hypotonic)
Composition	Riboflavin 5'-phosphate in 20% Dextran Ophthalmic Solution	Riboflavin 5'-phosphate Ophthalmic Solution
Function	Primary soaking agent to saturate the cornea and maintain saturation during irradiation.	Used specifically to swell the cornea if its thickness is below 400 microns.
Application Phase	Instilled during the initial 30-minute soaking period and throughout the 30-minute UVA irradiation.	Administered only after the initial soaking phase if ultrasound pachymetry reveals the cornea is too thin.
Key Additive	Contains dextran, a thickening agent that helps the solution stay on the cornea.	Does not contain dextran; its hypotonic nature draws fluid into the cornea.

Post-Procedure Expectations and Care

Aftercare is vital for healing.

Protection: A bandage contact lens is applied for protection.
Eye Rubbing: Do not rub eyes for five days.
Discomfort: Expect foreign body sensation, light sensitivity, and pain, manageable with medication.
Follow-Up: A follow-up removes the bandage lens and evaluates the eye.
When to Call the Doctor: Contact the doctor if the bandage lens falls out or for severe pain or sudden vision loss.

Conclusion

Photrexa administration is a precise, multi-step topical procedure combined with UVA light therapy. It involves removing the epithelium, soaking the cornea with Photrexa Viscous, checking for saturation and thickness, and then applying drops continuously during UVA irradiation. This process facilitates collagen cross-linking to strengthen the cornea and treat progressive keratoconus or ectasia. Proper post-procedure care is crucial for recovery. Consult manufacturer resources for detailed prescribing information.

Frequently Asked Questions

No, Photrexa is administered as eye drops, not as an injection. It is applied topically to the surface of the cornea as part of a corneal cross-linking procedure.

The procedure, often called 'epi-off' CXL, involves removing the corneal epithelium, saturating the cornea with Photrexa riboflavin drops, and then exposing the eye to UVA light from the KXL system.

The administration of Photrexa itself is part of a longer procedure. The initial soaking phase is 30 minutes, and the subsequent UVA irradiation phase with continued drop application is another 30 minutes.

Photrexa Viscous is the primary formulation used for saturating the cornea and contains dextran to increase its viscosity. Hypotonic Photrexa is a thinner solution used specifically to swell the cornea if it is too thin before irradiation.

The epithelium is removed to allow the Photrexa solution to fully penetrate the corneal stroma, which is essential for the cross-linking effect.

If your cornea is less than 400 microns thick after the initial soaking, a hypotonic Photrexa solution will be applied to increase its thickness before proceeding with UVA irradiation.

Aftercare includes not rubbing the treated eye for five days, wearing sunglasses to help with light sensitivity, and using prescribed antibiotic and anti-inflammatory eye drops.