1. Imaging the Posterior Segment Through a PMMA Keratoprosthesis
Aisha Traish MD, Kathryn Colby MD, PhD
World Cornea Congress VI
April 7-9, 2010
The authors have no financial interest.

2. Purpose
To describe imaging modalities to evaluate the posterior segment through the Boston keratoprosthesis Type I (KPro).

3. Methods
Retrospective analysis of all cases of Boston Kpro Type I patients of the Cornea Service at the Massachusetts Eye and Ear Infirmary ( ) who had limited post operative visual results with clear visual axes. Patients underwent complete ophthalmic evaluations and varying posterior segment imaging studies.

4. Case 1 81 year old retired physician s/p KPro OD Ocular hx:
S/p two penetrating keratoplasties (PKPs) for pseudophakic bullous keratopathy (PBK) OD
Post-operative vision after KPro was limited despite a clear anterior visual axis
Posterior imaging elucidated advancing macular degeneration as the etiology limiting his visual potential (see figures #1 and #2)

5. Figure 1: This fundus photograph of the right eye demonstrates calcified drusen scattered in the macula, particularly along the supero-temporal and infero-temporal arcades with some geographic atrophy.
Figure 2: This fluorescein angiogram of the right eye at 18.8 seconds demonstrates a window defect consistent with geographic atrophy; the absence of leakage excludes a choroidal neovascular membrane.

6. Case 2
87 year old male s/p keratoprothesis OD following three failed PKPs for PBK
History of glaucoma right eye
Post operative vision 20/60 declined to 20/100
no obvious anterior segment pathology
OCT imaging performed (see figure #3)

7. Figure 3: This grey scale OCT of the posterior segment in the right eye was performed post K pro implantation and illustrates clinically significant cystoid macular edema.

8. Case 3 56 year old woman with Stevens-Johnson Syndrome s/p KPro OS
Ocular history: PKP x 2, Open globe repair, Ahmed valve placement left eye
Postoperative vision: J16 at near, having trouble reading
SLO demonstrated irregular scotomas (see figure #4)
Recognition of her fixation within the scotoma allowed for low vision training to adapt her reading behavior

9. Figure 4: This scanning laser ophthalmoscope (SLO) image was taken of the left eye and illustrates irregular scotomas in the central field. The areas enclosed with grey lines and grey diagonal marks represent scotomas, while the areas of red dots represent seeing areas. Therefore, her center of fixation (black cross) lies within a scotoma.

10. Conclusion
Current posterior segment imaging modalities can be successfully used in patients with a keratoprosthesis and may aid the clinician in diagnosing post-operative posterior segment pathology that may limit visual potential.
Dedicated to Claes Dohlman, MD.