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CASE STUDY: Complexities in managing patients with corneal grafts

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Figure 1. Stromal neovascularisation of left corneal graft

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By Vianh Huynh
BOptom SpecCertMCLP SpecCertMPP

 

There are several challenges associated with managing patients following penetrating keratoplasty (PK). This article discusses some of the fitting considerations and highlights other complexities of managing corneal graft patients.

CASE REPORT

A 34-year-old male with bilateral keratoconus underwent left eye PK in 2013, then suffered one episode of endothelial rejection. Around two years after PK when the final suture had been removed, the patient was referred for contact lens correction.

He presented to the clinic wearing a miniscleral lens in the right eye (KATT 5.73/16.50/-16.00 (50/40E), VA 6/9.5++) and wished to get glasses to correct the vision in his post-graft (left) eye. Anterior segment assessment at this time revealed acute neovascularisation of the host cornea, extending approximately two millimetres into the graft tissue (Figure 1), despite the ongoing use of Predneferin Forte (b.i.d.).

Prompt referral to the patient’s ophthalmologist was arranged, resulting in a diagnosis of acute stromal graft rejection.

Three months later the patient returned, again hoping to get glasses for the left eye. He expressed a preference for avoiding a left contact lens entirely. A left spectacle correction of +1.75/-7.25x163 achieved 6/7.5+ visual acuity. A modified prescription of R Plano and L +0.25/-4.00x163 (L VA 6/9.5) was prescribed for glasses to wear in conjunction with the right contact lens.

The patient was advised to expect considerable aniseikonia from the spectacles, and therefore was also encouraged to trial a left contact lens.

Corneal topography of the left cornea revealed eight dioptres of irregular astigmatism with the flattest meridian at approximately 70 degrees (Figures 2 and 3).

 

CLF01 - Figure 2 - online

Figure 2. Placido image of left cornea

 

CLF01 - Figure 3 - online

Figure 3. Axial corneal topography map of left cornea

 

In selecting a trial lens for the left eye, there were several considerations.

  • Avoid a ‘sealed’ fit in order to minimise the risk of hypoxia due to poor tear exchange, especially as the integrity of the graft endothelium was unknown; that is, an endothelial cell count was not available.
  • Avoid focal areas of touch over any part of the cornea. The lens should predominantly be supported by the host cornea. Any lens support over the donor cornea should be as widespread as possible.
  • The requirement for a large optic zone and thus a large total lens diameter. Lenses smaller than the graft diameter can damage the junction, 1 uncommonly seen with larger lenses.2
  • Determine the appropriateness of a reverse geometry design.

To best satisfy these criteria, an ACL ‘Graft’ design lens was selected (7.60/10.50/-3.00) to be trialled (VA 6/12). This lens gave good subjective comfort and appeared centred and stable on the left cornea. The final lens order was: ACL Graft 7.60/10.50/-1.25 DS (Peripheries: 9.10 [0.30] 10.60 [0.30]) Boston XO2 (VA 6/7.5) (Figure 4).

 

CLF01 - Figure 4 - online

Figure 4. Fluorescein fitting pattern of left contact lens (ACL Graft 7.60/10.50/-1.25 DS)

 

Specific considerations apply when fitting contact lenses for corneal grafts, including protecting the integrity of the host-donor corneal junction, and the graft diameter and toricity.3

In fitting a corneal graft, the final fitting pattern is rarely the ideal three-point touch, but in these difficult cases achieving optimal vision and comfort, and minimising physiological insult to the cornea, can be considered the main priorities.

This case further highlighted other challenges affecting the corneal graft cohort, such as determining the appropriateness and post-operative timing of a contact lens fitting, monitoring the patient for signs of graft rejection or failure, and balancing patient comfort and preference regarding the mode of correction.

 

1.      Manabe R, Matsuda M, Suda T. Photokeratoscopy in fitting contact lens after penetrating keratoplasty. Br J Ophthalmol 1986; 70: 55-59.

2.      Daniel R. Fitting contact lenses after keratoplasty. Br J Ophthalmol 1976; 60: 263-265.

3.      Lindsay RG. Post-keratoplasty contact lens management. Clin Exp Optom 1995; 78: 223-226.



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