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Anterior segment A-OCT in monitoring low grade limbal ischemia and custom scleral lens design aiming the elimination of the clinical findings

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Lefteris Karageorgiadis, BScOptom^1, Nikos Vasileiou, BScOptom², Leonidas Mavroudis, MD³, Marina Banteka, MD³

 

1. EYEART Fitting center, Thessaloniki, Greece, 2.EYEART Laboratories, Thessaloniki, Greece, 3.   LMVision clinic, Thessaloniki, Greece

 

Free Papers I | Kassandros Hall | 21/10
Thursday, Oct 21, 2021
3:30 PM - 5:00 PM
KASSANDROS HALL

The 35th International Congress of the HSIOIRS (Hellenic Society Of Intraocular Implant and Refractive Surgery) will take place at “Ioannis Vellidis” Congress Centre in Thessaloniki, on 21-23 October 2021.

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Goal:

The preference of Scleral contact lenses (SCL) has been significantly increased by practitioners and patients, as they provide a stable optical surface in challenging cases of irregular astigmatism, without being in contact with the corneal surface. Nevertheless, non-optimal fitting and prolonged wear can cause circulation blockage in blood vessels, leading to possible corneal surface degradation and limbal ischemia. OCT-Angiography, well established for the posterior segment monitoring and diagnosis, may also be used to monitor blood vessel circulation of the conjunctival and scleral region on the anterior segment. Furthermore, angiography driven lens modifications can also be used for restoring reduced circulation.

 

Method:

Two cases of SCL wearers with reduced time for comfortable wearing (4-6 hours daily) underwent OCT-Angiography to capture conjunctival and scleral blood vessel circulation. Specially modified parameters have been used, to focus on the anterior segment. Based on the findings, new lenses were designed with custom scleral landing zone geometry, aiming to relieve and restore more fluent circulation. The same monitoring procedure is performed with the new SCL.

 

Results:

Substantial relieve of circulation was achieved and the comfortable wearing time has been doubled. A follow up clinical examination, 14 and 30 after the modified fitting, showed normal anterior surface physiology.

 

Conclusions:

Anterior segment OCT-Angiography’s technology can help in monitoring blood vessel circulation in areas that the SCL is supported, enabling an ameliorated custom design of the lens, that could minimize or even eliminate clinical findings, and increase patient comfort. The usability and repeatability of the OCT-Angiography can contribute in everyday clinical diagnosis and monitoring.

 

Scleral contact lenses are being manufactured by oxygen-permeable materials, with a diameter slightly larger than the soft contact lenses’, so that they can be applied on the sclera (the white of the eye), which has far fewer nerve endings than the cornea.

Due to their appliance on the cornea, scleral contact lenses are deemed as more comfortable for the users.

 

Except for the conformity that they provide, there are many other benefits in choosing scleral contact lenses:

 

1. They create a stable new visual surface that completely regulates the astigmatism and the abnormal astigmatism of the anterior surface of the cornea
2. No surface of the lens touches the cornea, which should not be 'rubbed' by the lens
3. The circumference of the lens 'closes' on the sclera so that their position is stable and so that they do not shift during each use
4. The attributes mentioned above make scleral lenses the most comfortable lenses for the user
5. They are not easily affected by external conditions. No dust gets under the lens, they do not move when a lot of water comes into contact with the users’ face and they are not displaced by air

 

Keratoconus is an optical condition in which the cornea i.e., the transparent tissue at the front of the iris, shows a greater curvature in one area and is often thinner.

This can be accompanied by blurred and distorted vision, due to the fact that the light is not focused properly in the depth of the eye, often showing myopia and abnormal astigmatism.

Contact lenses are the main solutions which correct vision in such cases, and they should have a personalized design for everyone. Different types of lenses are ideal for different people or types of keratoconus. The optometrists who apply such lenses inform the patients of the different solutions, providing the best fit for their case and needs.

 

The best types of contact lenses for keratoconus in 2021 are the following:

 

• Scleral lenses: These lenses have a larger diameter than the standard soft lenses, which are applied to the white of the eye without touching the cornea, creating a stable optical surface that corrects sharp visual aberrations and distortions. For people who are participating in sports and generally have an active daily life, we recommend the EPSILON scleral contact lenses, which are the most popular choice for keratoconus.
• Personalized soft lenses: These are specially designed which include astigmatism treatments, and due to the special design in their optical zone, they significantly reduce the conical shape of the cornea. The advanced soft keratoconus lenses DELTA CONUS in most cases offer the same quality of vision as the scleral lenses. Also due to the choice of materials, they can be frequently replaced, usually within three to six months.
• Scleral air permeable corneas: This is the type of lens that has been used most frequently, because it used to be the only type of contact lens that could correct keratoconus, for several decades. The size of the lenses is smaller than the cornea and combined with its stable construction material, it provides good visual acuity and at the same time provides continuous alternation of tears under the lens. Its reduced stability, compared to other types of lenses, increases the feeling of a foreign body on the eyelids, making the its adaptation more time consuming to new users. Such lenses are DUALASCON.