Combined Cross-Linking and Topography-Guided Laser (CXL Plus)

A combined method that aims to reduce the irregularity while halting progression in suitably selected keratoconus patients — suitability is assessed with Dr. Nejmi Öztürk, ophthalmologist and eye surgeon, at HG Hospital in Kahramanmaraş, Türkiye

What is combined cross-linking and topography-guided laser?

Combined cross-linking and topography-guided laser (CXL Plus) is the application, in the same session, of a limited surface laser planned according to the topography map to a cornea with keratoconus, immediately followed by strengthening of the cornea with cross-linking. The laser removes very little tissue from the most irregular areas of the cornea to make the surface smoother; cross-linking aims to halt progression so that this new shape is preserved.

The goal of this method is not to bring the glasses prescription down to zero. Because a cornea with keratoconus is weak, a full correction as in standard refractive laser (laser eye surgery) is not done; a limited amount of tissue, usually not exceeding 50 microns, is removed. The aim is to reduce the irregular astigmatism and image distortions and to provide better and more comfortable vision with glasses and contact lenses.

The surface laser technique is similar to the PRK and No-Touch methods: no corneal flap is created, and the tissue is removed from the surface of the cornea. Cross-linking itself is explained on a separate page; for all the treatment steps of keratoconus, see the keratoconus treatment page.

Who is the combined treatment suitable for?

The combined treatment is suitable for keratoconus patients whose cornea is thick enough, who are at a mild-to-moderate stage and who cannot achieve adequate vision with glasses. Patient selection is the most important step in determining the result of this method.

• Sufficient corneal thickness: The thinnest point before the laser is usually expected to be 450 microns or more, with at least 400 microns remaining for cross-linking after the laser.
• Mild-to-moderate stage: Eyes whose corneal steepness is not excessively high and whose center has no scar.
• Poor vision with glasses: Patients for whom glasses are inadequate because of irregular astigmatism, or who cannot adapt to contact lenses.
• Realistic expectations: Patients who accept that the aim is to reduce the irregularity and that the need for glasses or lenses may continue.
• Age: Usually 18 and over; it can be applied in patients with documented progression or in stable patients.

Who is it not suitable for?

• Patients with a thin cornea: Removing tissue weakens the cornea further; in these patients only cross-linking or ring segments are considered.
• Advanced keratoconus: In a very steep and irregular cornea the benefit of the laser is limited; scleral lenses or a corneal transplant come into consideration.
• People with a central corneal scar: The scar continues to limit vision.
• People who expect to be completely free of glasses: This method does not meet that expectation.
• Active eye infection, severe dry eye, previous herpes keratitis, pregnancy and breastfeeding: The restrictions that apply to cross-linking apply here too.

Which examinations and tests are done before the procedure?

The plan for the combined treatment is made according to the map obtained from corneal topography and tomography; where and how much tissue the laser will remove is calculated from this map.

• Corneal topography and tomography: Several measurements are taken to check consistency; the laser plan is generated from this map.
• Pachymetry (thickness map): The thickness that will remain after the laser is calculated.
• Vision and glasses prescription measurement: Vision with and without glasses is recorded; the target for the partial correction is set.
• Biomicroscope examination and tear assessment: If there is dry eye or eyelid inflammation, it is treated first.
• Dilated retinal examination: Another cause that could limit vision is ruled out.

How is the combined treatment performed?

The combined treatment is performed with anesthetic drops, under operating-room conditions, in a single session of about 45–60 minutes; the patient is awake and goes home the same day.

1. Preparation: Anesthetic drops are applied; the eyelids are held open with a small device.
2. Removal of the epithelium: The outer cell layer of the cornea is removed with the laser (transepithelial approach) or by manual scraping.
3. Topography-guided surface laser: The excimer laser removes a limited amount of tissue from the irregular areas of the cornea according to the map calculated in advance. This stage takes between a few seconds and one to two minutes; the patient looks at a light during this time.
4. Riboflavin application: Riboflavin drops are absorbed into the cornea; the time is 10–30 minutes depending on the protocol.
5. UV-A light: The cornea is exposed to UV-A light for 3–30 minutes according to the accelerated or standard protocol.
6. Closing: Antibiotic drops and a bandage contact lens are applied.

Pain is not expected during the procedure; a sensation of light, a smell and pressure is normal. Once the drops wear off, stinging, burning and watering are marked in the first 2–4 days. In some patients the laser and cross-linking can also be done in two separate sessions months apart; the sequence is decided for each patient.

Combined treatment step by step

Reducing surface irregularity with a topography-guided laser, followed by cross-linking in the same session; shown schematically on a corneal cross-section.

1. Reshaping the surfaceThe topography-guided laser reduces the irregularity identified on the map by removing a limited amount of tissue. The aim is not to bring the glasses prescription to zero but to regularize the surface.
2. Applying riboflavinIn the same session riboflavin drops are applied and allowed to soak into the tissue.
3. Applying UV-A lightUV-A light is applied to strengthen the structure. This aims to preserve the corrected surface.

What is recovery like?

Recovery is similar to cross-linking, but because tissue has been removed with the laser, vision takes a little longer to settle; the final result is assessed after 6–12 months.

• Day 1: Stinging, watering and light sensitivity are marked; the bandage lens is in place. The eye is not rubbed; the prescribed drops are used regularly.
• Days 3–5: The epithelium heals over and the bandage lens is removed. Vision is blurred and fluctuates.
• Week 1: The stinging largely passes. Return to desk work is possible; for dusty work, wait 2 weeks.
• Month 1: Vision approaches or exceeds the level before the procedure; slight haziness inside the cornea (haze) may be seen. The steroid (cortisone) drops are continued at a reduced dose.
• Months 3–6: The reduction in irregularity becomes visible on the map; new glasses or lenses are planned in this period.
• Month 12: The corneal map is compared with the one before the procedure; whether progression has stopped and whether the correction is lasting are assessed.

For patients coming from districts such as Elbistan, Afşin and Göksun, the day 1 and bandage-lens removal check-ups are planned close to the day of the procedure; because the later check-ups are spaced out, the number of journeys stays limited.

What are the risks and limitations?

The combined treatment carries slightly more risk than cross-linking alone, because tissue is removed from a cornea that is already weak. Results vary from person to person.

• Corneal haze: Seen more often than with cross-linking alone; it usually settles within months and can rarely be permanent.
• Under- or over-correction: The response of the cornea may be unpredictable; the glasses prescription may end up different from the target.
• Regression: The improvement gained may be partly lost over time.
• Continued progression: In a small group of patients keratoconus may continue to progress.
• Infection and delayed healing of the epithelium: Rare; the drop schedule and the check-ups reduce the risk.
• Dry eye, light scatter, night halos: May be seen in the first months; they usually decrease.
• Corneal thinning: The removed tissue does not grow back; this is why the thickness requirement is applied strictly.

Limitations: The method does not aim to remove the need for glasses or lenses. The gain in vision depends on the degree of irregularity of the cornea; in some patients visual acuity does not change, while image quality and lens tolerance improve.

What are the alternatives, and how do they compare?

Method	Halting progression	Effect on vision	Corneal thickness requirement	Details
Cross-linking alone	Yes, this is its aim	Not the aim; slight improvement possible	Usually at least 400 microns	Cross-linking
Combined CXL + topography-guided laser	Yes	Reduces the irregularity; partial correction	Usually 450 microns or more	This page
Intracorneal ring segments (+ CXL)	Yes, together with CXL	Flattens the cone; partial correction	Sufficient thickness in the ring zone	Keratoconus treatment
Contact lenses (RGP, hybrid, scleral)	No	Good vision at most stages	No requirement	Keratoconus treatment
Standard refractive laser (LASIK, SMILE, PRK)	No; not performed in keratoconus	—	—	Laser eye surgery

Assessment and planning in Kahramanmaraş

Your suitability for this method is assessed with the examination and measurements at HG Hospital in Kahramanmaraş, Türkiye; the method that suits you is planned together. The keratoconus examination, corneal maps and thickness measurement are carried out at HG Hospital by Dr. Nejmi Öztürk, ophthalmologist and eye surgeon, and whether the combined treatment is suitable is determined according to these measurements.

Cross-linking may be covered by SGK under certain conditions; for the laser part of the combined treatment, the conditions of coverage are clarified at the consultation. HG Hospital is a private hospital contracted with the Turkish social security institution (SGK); patients with valid SGK coverage may use it, although a private-hospital co-payment may apply. Patients without SGK coverage, such as international patients and visitors from abroad, pay privately or through their private or travel health insurance; the hospital checks coverage before treatment. Fee information is given by the hospital after the examination.

Patients from Elbistan, Afşin, Göksun, Ekinözü and Nurhak come to HG Hospital in the center of Kahramanmaraş for the assessment; Dr. Öztürk does not see patients in Elbistan. The measurements are completed on the same day as far as possible; for travel and planning information, see the Elbistan and the surrounding area page.

Frequently asked questions

Sources

• Turkish Ophthalmological Society — todnet.org
• American Academy of Ophthalmology (AAO) — aao.org
• European Society of Cataract and Refractive Surgeons (ESCRS) — escrs.org

Related pages

• Keratoconus treatment
• Corneal cross-linking (CXL)
• PRK and No-Touch surface laser
• Wavefront- and topography-guided laser

This page is for information only; diagnosis and treatment decisions are made after an examination. The results of any surgical or interventional procedure may vary from person to person. You are advised to obtain detailed advice from your physician before any procedure.