Experts’ opinion – Case 10

In addition to answering the questions posed to our members, our Experts were also asked the following questions :

1) Supposing a secondary IOL implant is preferred; there is a possibility of irregular astigmatism. What other options can you suggest as an alternative to CL?
2) Do you think it is important to correct near vision? If so, how?
3) Do you agree with the surgical choice of the Mushroom PK?

Dr. Brenda Breidenstein

(1) Could a secondary IOL implant be a choice for the future?
Yes; a secondary IOL implant could be considered once suture removal is complete after PK, and post-operative refraction has stabilized.

(2) Supposing a secondary IOL implant is preferred, when would it be preferable?
If a secondary IOL implant is to be placed, it should be done after astigmatism has stabilized and residual astigmatism has been treated, if desired.

(3) Which surgical IOL solution would you prefer?
I would prefer scleral fixation of the lens in this case. Iris fixation is also an option, if suture fixation is to be used I would recommend the use of a 9-0 suture rather than a 10-0 as lens dislocation may occur years after placement. An iris claw lens could also be used in which case retropupillary placement would be preferred to decrease risk of corneal endothelial decompensation. I would avoid placement of an angle fixated lens due to long term risks of corneal endothelial decompensation as well.

(4) Supposing a secondary IOL implant is preferred; there is a possibility of irregular astigmatism. What other options can you suggest as an alternative to CL?
Surgical treatment of residual high astigmatism after mushroom PK has been reported by Fung et al. using arcuate mushroom interface dissection, which significantly decreased astigmatism and improved UCVA and CVA.

(5) Do you think it is important to correct near vision? If so, how?
Yes; In this case I’d recommend near vision correction with spectacles.

(6) Do you agree with the surgical choice of the Mushroom PK?
I would agree with the choice of mushroom PK for this patient. This technique uses a tiered graft which typically consists of an anterior lamellar graft of 9mm diameter superficially and a 5-6mm base consisting of deep stroma and endothelium. This has the advantage of removing less of the recipient endothelium and causing less immunogenicity. This is desirable in cases where the recipient has healthy endothelium, for example corneal scars or thinning as in keratoconus. The mushroom PK configuration may also be more stable and result in less astigmatism. This procedure is technically difficult, however use of femtosecond laser has the potential to simplify the dissection.

 

Dr. Massimo Busin

(1) Could a secondary IOL implant be a choice for the future?
After suture removal an IOL can be safely implanted on the residual posterior capsule, probably with no need for trans-scleral fixation. In any case, if the child wears a hard CL comfortably, this can be used as well with excellent results.

(2) Supposing a secondary IOL implant is preferred, when would it be preferable?
It is better to wait for the astigmatism to stabilization after suture removal in order to have a more precise IOL calculation. At 9 years of age the PK wound is healed and sutures must come out to avoid long-term complications. One of the advantages of the “step wound” obtained with the mushroom keratoplasty, is that residual astigmatism can easily be corrected by relaxing the wound all the way into the AC for 2-3 hours of the clock, because the wound is of the self-sealing type (a 360° clear cornea tunnel).

(3) Which surgical IOL solution would you prefer?
I prefer scleral fixated IOL because of the more physiological position of the IOL and to prevent damage on corneal endothelium for the excessive proximity. Another advantage is to restore partial separation between the posterior chamber and the vitreous cavity.

(4) Supposing a secondary IOL implant is preferred; there is a possibility of irregular astigmatism. What other options can you suggest as an alternative to CL?
A surgical option could be the repetition of the anterior LK, with the substitution only of the hat of the mushroom keratoplasty.

(5) Do you think it is important to correct near vision? If so, how?
Yes of course, it is important to correct near vision, spectacles are a good option.

(6) Do you agree with the surgical choice of the Mushroom PK?
Yes, I agree with the surgical choice of mushroom PK.

 

Dr. Pravin Krishna Vaddavalli

(1) Could a secondary IOL implant be a choice for the future?
A secondary IOL implantation would certainly be important to consider due to the following reasons:
• This is a 9-year-old child, compliance with care regimes for wearing a contact lens long term would be challenging in this age group with risk of infections and inflammatory keratitis.
• A contact lens provides about 8 to 10 hours of corrected vision; the child would be uncorrected for the rest of the day. While the child is older and amblyopia may not be a major concern, functionally it does limits activities and a normal lifestyle.
• A contact lens over a penetrating graft could cause more hypoxic changes than in an un-operated eye. This may not be an issue short term but would be so in the long term with reducing endothelial cell counts.

(2) Supposing a secondary IOL implant is preferred, when would it be preferable?
Since a secondary IOL in this situation cannot provide toric correction, the timing of surgery is not dictated by the timing of suture removal and can be planned based on the success of the contact lens wear.

(3) Which surgical IOL solution would you prefer?
I would prefer a scleral fixated IOL, either sutured or by externalization of the haptics for multiple reasons :
• An iris fixation would be challenging due to the dense membrane posteriorly, making the iris much more rigid. This would make fixating a lens with claws challenging as sufficient iris tissue may not be enclavated. A similar challenge is likely to be faced with both anterior iris or iris retrofixation.
• Since the crystalline lens was lost during the trauma, sulcus fixation would not be possible.
• Angle fixation could compromise the endothelium of the graft and in the long term in a young individual, lead to angle changes and glaucoma.

(4) Supposing a secondary IOL implant is preferred; there is a possibility of irregular astigmatism. What other options can you suggest as an alternative to CL?
An IOL will not be able to correct for irregular astigmatism. I would wait for all sutures to be removed and perform a topography guided surface ablation with an excimer laser to smoothen the surface to achieve correction of irregular astigmatism.

(5) Do you think it is important to correct near vision? If so, how?
Near vision correction may not be important in this scenario, as the contralateral eye should suffice in providing adequate near vision. My goal would to be achieve the best possible distance vision correction.

(6) Do you agree with the surgical choice of the Mushroom PK? The choice of a mushroom keratoplasty is an excellent one, maximizing the protection of the host endothelium, while reducing the impact of sutures and graft host junction on astigmatism. The only downside might be when eventually the graft fails, performing an endothelial keratoplasty might be more challenging as the posterior graft host junction being more central, may impact graft adherence due to prominent posterior graft host junction.

 

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