Transcript Use of a PMMA Keratoprosthesis in Severe Ocular Chemical Burn

The Use of a PMMA Keratoprosthesis in
Severe Ocular Chemical Burn
Fabiano Cade, Allyson Tauber, Claes H. Dohlman
Massachusetts Eye and Ear Infirmary
Harvard Medical School
Boston, MA, USA
The authors have no financial interest.
Introduction
• Ocular chemical burns are often devastating injuries that cause
vision loss and structural damage to both the ocular surface and
internal ocular tissues; (1,2)
• Visual prognosis often depends on the degree of ocular surface
damage; (2)
• Strategies for vision rehabilitation after severe ocular chemical
burns remain a challenge . The impact of stem cell loss on longterm corneal graft survival is a problem; (3,4)
Purpose
• To evaluate the outcomes of the Boston Keratoprosthesis
(BKPro) after severe ocular chemical burns;
Methods
• A retrospective review of charts was performed on all 24
patients (29 eyes) with severe chemical burns who underwent
BKPro surgery at the Massachusetts Eye & Ear Infirmary
between 1990 and 2008.
•We analyzed preoperative and postoperative parameters such
as the type of chemical burns, number of BKPro surgeries,
visual acuity and complications.
Results
• The 24 patients (29 eyes) in this study were followed for a
mean of 57 months (range 1-162 months).;
•Sixteen eyes had an alkaline burn, 12 an acidic burn and one
eye was not possible to identify the type of chemical burn;
•Twenty-two eyes retained their initial BKPro throughout the
follow-up course and seven eyes required repeat BKPro
surgeries. Reasons for BKPro replacement were either varying
degree of stromal melting in seven eyes or skin overgrowth on
the BKPro type II optical surface (one eye);
Results
• Preoperative visual acuity was counting fingers or worse in all
eyes. Fifteen eyes (52%) achieved 20/50 or better VA at some
point during their follow-up, but only seven (24%) maintained
20/50 at the last follow-up (Figure 1);
Results
• A Kaplan-Meier survival analysis was performed to evaluate
the patients who retained VA of 20/200 or better at their last
follow-up (Figure 2);
Results
• The number of eyes with a preoperative history of glaucoma
was 21 (72%), and three more eyes developed glaucoma
postoperatively (table 1);
Number of eyes
Pre-BKPro glaucoma
21
(of those, severe progression)
(8)
Additional post-BKPro glaucoma (de novo)
3
No glaucoma
5
Table 1. Glaucoma in BKPro operated chemical burn eyes. Pre-BKPro glaucoma was diagnosed by signs
immediately post BKPro surgery or when optic nerve obscured, by firm history.
Results
• Postoperatively, a retroprosthetic membrane (RPM) developed
in 12 eyes (41%), and retinal detachment (RD) in eight (27%).
Fungal endophthalmitis occurred in one eye but was cured by
medical therapy. Other complications in lower numbers are
enumerated in Table 2.
RPM
New retinal detachment
Skin overgrowth
Leak
Hypotony
Melt
Device extrusion
Back plate loosening
Maculopathy
Phthisis†
Vitritis
Keratitis
Choroidal detachement
Suprachoridal hemorrhage
Endophthalmitis (fungal-cured)
Vitrous hemorrhage
N = number of eyes; RPM = retroprosthetic membrane;
† Phthisis without combination with retinal detachment;
some patients had more than one complication;
Table 2. Post-BKPro complications beyond glaucoma.
N
12
8
6
5
4
4
2
2
2
2
2
2
2
1
1
1
%
41
27
21
17
14
14
7
7
7
7
7
7
7
3
3
3
Discussion
•This study shows that a BKPro can give excellent visual acuity
(VA) after surgery, even in very severe corneal burns ;
•However, during follow up (here up to 5 years) there was a
gradual VA decline. In cohorts of BKPros done in relatively non
inflamed graft failures, a lesser VA decline is usually seen ; (5)
•There was a remarkable difference between the latest recorded
VA regarding patients with Alkali and Acid burns. Generally,
alkali penetrates deeper than acids and the well-known
difference in visual outcome after types of burns is confirmed
here; (2)
Discussion
•The most important preventable problem is glaucoma;
• 21 out of 29 had advanced glaucoma damage with optic nerve
cupping already at the time of the BKPro implantation. Thus,
aggravation of pre-existing glaucoma after surgery as well as de
novo appearance of elevated pressure in other cases are all
difficult to control;
•Due to the frequency of glaucoma in chemical burns, before
and after KPro, glaucoma drainage devices and
cyclophotocoagulation should be considered as soon as
glaucoma medication fails to maintain pressure in the midteens;
Discussion
•Although RPM formation was the most frequent postoperative
complication seen after BKPro, it was successful treatable with
YAG Laser;
•RD was the main severe complication within one year after
BKPro implantation in this cohort. However, out of the 8 RD
patients, three had previously presented bad vision due to
endstage of glaucoma.
Conclusion
•The advent of a KPro with high degree of retention has changed
the treatment of severely burned corneas. However, restoration
of clear media in many such cases has revealed further
problems, particularly glaucoma. Prevention of glaucoma after
burns must now be given top priority.
References
1. Pfister RR. Chemical injuries of the eye. Ophthalmology, 1983. 90(10):1246-53.
2.Wagoner MD. Chemical injuries of the eye: current concepts in pathophysiology and
therapy. Surv Ophthalmol, 1997. 41(4): 275-313.
3.Schrage NF, Langefeld S, Zschocke J, Kuckelkorn R, Redbrake C, Reim M. Eye burns: an
emergency and continuing problem. Burns, 2000. 26(8):689-99.
4.Tuft SJ, Shortt AJ. Surgical rehabilitation following severe ocular burns. Eye (Lond), 2009.
23(10): p. 1966-71.
5.Yaghouti F, Nouri M, Abad JC, Power WJ, Doane MG, Dohlman CH. Keratoprosthesis:
preoperative prognostic categories. Cornea, 2001. 20(1):19-23.