Keratoconus and Cross-linking Treatment
Frequent changes in the spectacle prescription, increasing astigmatism, or an image that does not become sufficiently clear despite new glasses may require the structure of the cornea to be assessed. One of the possible causes of these complaints is keratoconus.
Keratoconus is a condition in which the cornea, the transparent layer at the front of the eye, thins and changes shape, affecting vision. Treatment has two separate aims: improving vision as far as possible and bringing the progression of the condition under control.
In assessing keratoconus, Op. Dr. Gökay Günay considers the general eye examination, corneal maps, thickness measurements and previous investigations together. The follow-up or treatment plan is drawn up according to the characteristics of each eye and the risk of progression.
What Is Keratoconus?
The regular structure of a healthy cornea helps light to focus on the retina. In keratoconus, thinning of the cornea and its irregular forward steepening may disturb the focusing of light.
As a result, irregular astigmatism, blurred vision, shadowed images and scattering around lights may be seen. The condition usually affects both eyes; however, the severity and the rate of progression may differ between them.
What Are the Symptoms of Keratoconus?
The complaints that may be seen in keratoconus are as follows:
- Frequent changes in the spectacle prescription or in astigmatism
- Not achieving the expected clarity with glasses
- Shadowing around the edges of text and objects
- Seeing double or multiple images when looking with one eye
- Scattering and glare around lights at night
- Changing vision or comfort with contact lens wear
These symptoms do not on their own establish a diagnosis of keratoconus. Dry eye, the spectacle prescription and other eye conditions may also cause similar complaints.
What Causes Keratoconus? Does Rubbing the Eyes Play a Part?
Genetic predisposition and environmental factors may play a part together in the development of keratoconus. A family history of keratoconus is taken into account during the assessment.
Rubbing the eyes frequently and forcefully is associated with the condition. In people with itching and allergy in particular, the habit of rubbing should be asked about and the cause of the itching treated.
Which Investigations Are Performed in a Keratoconus Examination?
The assessment begins by discussing the complaints and the history of spectacle wear. The general eye examination examines the level of vision, the refractive error, the cornea and the ocular surface. Any other investigations required are determined according to the examination findings.
Corneal Topography and Tomography
Corneal mapping investigations assess the shape of the cornea and the distribution of its curvature. Depending on the system used, tomography provides information about the front and back surfaces of the cornea and the distribution of its thickness.
These measurements are important in detecting keratoconus and in monitoring change over time. Decisions are not made on the basis of a colour or a number on a single map; the quality of the measurement and the examination findings are assessed together.
Corneal Thickness Measurement
The thickness of the thinnest area of the cornea and the distribution of thickness across the cornea are examined. Alongside the assessment of the condition, this information is used in determining suitability for cross-linking and the method that may be applied.
Comparison with Previous Measurements
Previous spectacle prescriptions, corneal maps and examination reports help progression to be assessed. As contact lenses may affect the shape of the cornea, any pause in wear before measurement is advised according to the type of lens used.
How Is Keratoconus Treated?
The choice of treatment varies according to the stage of the condition and whether it is progressing. Measures that support vision and treatments intended to control progression have different functions.
Glasses may be sufficient in the early stages. Where adequate vision cannot be achieved with glasses, specialist contact lenses may be assessed. In suitable patients, options such as intracorneal rings may be considered, and in advanced cases corneal transplantation may arise.
The main aim of cross-linking treatment is to strengthen the cornea in an attempt to halt the progression of the condition. Not every patient with keratoconus needs the same treatment.
What Is Cross-linking and How Is It Performed?
Cross-linking is a procedure intended to increase the strength of the corneal tissue using drops containing riboflavin, a form of vitamin B2, together with controlled ultraviolet A light.
The treatment is carried out under anaesthetic drops. Depending on the method to be used, the surface layer of the cornea may be removed. Following the application of riboflavin, light treatment is delivered according to the chosen protocol. Where required, a protective contact lens is placed at the end of the procedure.
The duration of the procedure and the healing process vary according to the protocol used. Before the procedure, the reasons for the chosen method, the expected benefits and the possible risks are explained.
Who Is Suitable for Cross-linking?
Cross-linking is assessed particularly in patients whose keratoconus is progressing. Young age, changes in the corneal maps, thinning and visual findings are important in the decision-making process.
In some patients, the decision to treat may be taken earlier because of the risk of progression. The thickness and clarity of the cornea and other ocular findings affect suitability for the procedure.
The same protocol cannot be applied to every patient with a thin cornea. The decision to treat is not made on the basis of age or a single thickness value alone.
Does Cross-linking Mean Freedom from Glasses?
Cross-linking is not an operation to remove the need for glasses. The main aim is to try to prevent further change in the shape of the cornea and the loss of vision associated with it.
In some eyes there may be an improvement in vision or in the shape of the cornea over time; however, this outcome cannot be guaranteed. The need for glasses or specialist contact lenses may continue after treatment.
Recovery and Check-Ups After Cross-linking
Particularly after procedures in which the surface layer of the cornea has been removed, there may be pain, stinging, watering, sensitivity to light and blurred vision during the first few days.
Healing of the surface and stabilisation of vision do not occur over the same period. Vision and the spectacle prescription may fluctuate for a time. Drops should be used as advised; the protective contact lens should not be removed or reinserted by the patient.
Check-ups monitor the healing of the cornea, the level of vision and changes in the corneal maps. The return to work, school, driving and contact lens wear is determined by individual assessment.
Risks such as infection, clouding or scarring of the cornea and reduced vision exist. Assessment is required without delay in the event of increasing pain, redness or a marked deterioration in vision.
Why Is Regular Follow-Up Important in Keratoconus?
The rate at which keratoconus progresses varies from person to person. The follow-up interval is determined according to age, previous measurements and the risk of progression.
Having had cross-linking does not mean that check-ups come to an end. The structure of the cornea and vision need to be monitored after treatment as well.
At Op. Dr. Gökay Günay’s practice in Nişantaşı, Şişli, the assessment and follow-up plan is drawn up by considering previous investigations together with the current examination findings.
Frequently Asked Questions
Can People with Keratoconus Have LASIK or SMILE?
Keratoconus is a significant obstacle to standard laser procedures that correct the spectacle prescription. Removing tissue from the cornea may increase its structural weakness. The specific treatment combinations assessed in selected patients are not the same as standard procedures to remove the need for glasses.
Is Cross-linking Needed If Keratoconus Is Not Progressing?
In eyes that show no progression and are at low risk, regular follow-up may be sufficient. The decision is made by assessing age and the measurements together. Not every diagnosis of keratoconus automatically requires surgery.
Can Cross-linking Be Repeated?
In some eyes in which progression is detected after treatment, a repeat procedure may be assessed. First, the change in the measurements needs to be confirmed and the suitability of the cornea for repeat treatment examined.
Should I Have an Examination If There Is Keratoconus in My Family?
A family history should be mentioned at the examination. Corneal assessment is particularly important where there is changing astigmatism at a young age or vision that is not adequately corrected with glasses.
This information is for general guidance only; it does not replace individual medical assessment. Every surgical and interventional procedure carries risk. Suitability for treatment is determined by examination.