Debates in management of keratoconus

Controversies In Management Of KeratoconusBY Dr. Amr Mounir Lecturer of ophthalmologySohag university

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1- Unstable disease 2- Progressive 3- No treatment modality is sufficient 4- No treatment is satisfactory to the patient . 5- Needs to stabilize the disease and then optical correction .Why keratoconus management is still a problem ???

First : CXL

Second : ICR

Third : Toric ICL

Recent treatment modalities

After practicing these techniquescontroversies have appeared

About CXL

1- Epi.on or Epi.off2- Haze after Crosslinking.3- High Fluence CXL

Controversies

Which is better ?????

CXL is done by riboflavin and UV.A to crosslink the collagen bundles of the cornea. Riboflavin cannot cross the intact corneal epithelium so epithelium is removed to load the stroma with it. In Epi.on CXL certain formulas of riboflavin can penetrate intact epithelium so epithelium removal isn't needed Epi.on. is it effective ???

Good anterior chamber flare

Good corneal soaking

Epi.off has a lot of complications

Complications of Epi.off CXL

Complications of Epi.off CXL

Complications of Epi.off CXL

Complications of Epi.off CXL

A 32 ys old male with keratoconus grade (1) Subjected to Epi-on CXl ,Preoperative refraction :-5 Ds -5Dc @74 with BCVA : 6/48 From our short experience in Sohag Future Center for Corneal surgeries

Preoperative Pentacam

Post.Epion CXL Pentacam after 3 weeks only

-5 Ds -3Dc @ 72 with BCVA : 6/24

Avg K: Decrease by 2 DsCylinder : Decrease by 2 Dc

Postoperative refraction

Although Epi-off CXL is still more effective than Epi-on , However Epi-on CXL is safer and effective CXL technique which show very promising results in management of Keratoconus Conclusion

1- Stage 1 < or = 49 Ds2- Clear cornea3- BCVA > or = 6/12 Indications of CXL

1- Thinnest point < 360 um2- Central corneal opacity 3- Age > 40 ys4- Low compliance of the patient Contraindications

Haze after CXL

Haze after CXL is different in clinical character from haze after other procedures, such as excimer laser photorefractive keratotomy. The former is a dust-like change in the corneal stroma or a midstromal demarcation line, whereas the latter has a more reticulated subepithelial appearance. Similarly, the mechanisms leading to haze formationmay be different

Slit lamp Examination 2) Scheimpflug image densitometry measurements Evaluation :

Scheimpflug image densitometry

After CXL, 1) Concomitant changes in the corneallamellar array and spacing may lead to an increasein light scatter and a decrease in transparency. 2) A significant increasein collagen fibril diameter, with increasedspacing between collagen fibrils, after CXL. Thismay also play a role in decreased cornealtransparency.Theories for haze

3) CXL leads to an almost immediate loss of keratocytes in the corneal stroma, activatedkeratocytes repopulated the corneal stroma, It is possible that these activated keratocytes contribute to the development of CXL associated corneal haze.

1) Mild haze is considered a normal finding in most of cases and even a sign of success and usually doesn't affect vision 2) Mild Haze is usually paracentral in position and regressing in course with topical steriods 2) Risk factors for severe haze include advanced keratoconus and Epi-off CXL. Haze , is it a problem ?

Mild haze in postoperative epi-off CXL in The Future center for corneal surgeries

Severe haze

High Fluence CXL

High intensity CXL includes delivery of Higher amount of energy by high fluence CXL devices which will lead to shortening the operation time.This technique is based on a law of physics Bunsen- Roscoe it states that an effect should stay the same , If the total energy remains the same

To short the exposure time 1- Decrease dehydration time 2- To lessen keratocyte damage Aim of high fluence CXL

Preliminary results about high fluence CXL show a good safety profile as It affects neither endothelial density nor speed of epithelial healing which is an indicator of limbal stem cell function. Is it safe ???

However , further evaluation is needed to determine the biochemical effects and overall safety profile, and also the we should note that CXL is an oxygen dependant process that depends on intrastromal oxygen concentration which will be consumed more with higher fluencies so it may affect the treatment efficacy. Controversy

Oxygen and CXL

To compensate for low oxygen , pulsed CXL is recommended

The KXL System (Avedro) accelerated CXL

Treatment parameters for Transepithelial crosslinking

About ICRs

1- Which type to use ??2- Are they effective??3- Combined CXL and Rings

Intacs

Ferrara ring

MyoRing

1- INTACS : Implanted in a 6mm diameter of the visual axis Reduction in its use has occurred after appearance of other types of rings which implanted in 5mm diameter .NB: the nearer to the visual axis the more flattening effect .Which Type to use ???

2- Kerarings :Most commonly used , implanted in 5mm diameter around the steepest axis. - Wide range of ring dimensions for different refractions and keratometry readings.

Keraring

Nomogram for Keraring

Tunnel creation by Femtosecond laser

Kerarings Ring implantation

Pentacam image shows area of central flattening effect of Kerarings with regularization of the corneal surface

3- Myoring :The most recent type , one segment ring , mainly indicated for central (nipple) cone .

Myoring

The nomogram for selection of a type of ring depends mainly on central average corneal keratometry (average Sim K) Nomogram for myoring (average Sim K)Implant diameterImplant thickness< 447 mm280um44