Laminar Resorption in Modified Osteo-odonto-keratoprosthesis Procedure: A Cause for Concern




Purpose


To analyze the cases of lamina resorption following the modified osteo-odonto-keratoprosthesis (MOOKP) procedure.


Design


Retrospective case series.


Patients and Methods


Case records of 18 eyes (20 laminae) of 17 patients who showed evidence of lamina resorption out of the 85 eyes (87 laminae) of 82 patients that underwent MOOKP procedure between March 2003 and March 2013 were analyzed.


Results


Of the 17 patients (20 laminae), 1 underwent MOOKP procedure following multiple graft failures, 6 (7 laminae) belonged to the chemical injury group, and 10 (12 laminae) to the Stevens-Johnson syndrome (SJS) group. Resorption was noted in 20 out of 87 laminae (22.98%). The need for removal of lamina/extrusion was noted in 3 out of the 7 laminae in the chemical injury group and 8 out of the 12 laminae in the SJS group. The mean duration to the first sign suggestive of resorption among patients of SJS was 36.7 months and among patients of chemical injury was 43 months. Vitritis was the presenting feature (7 of 20 laminae, 35%) indicative of early resorption, and the occurrence of the same in eyes with lamina resorption was noted to be statistically significant in comparison to controls ( P < .001). Sixteen out of 20 laminae showed evidence of resorption superiorly.


Conclusion


Vitritis was the most common presenting feature of lamina resorption and could be an indicator of lamina resorption. Resorption of the laminae was noted to occur along the aspect with thinner bone support in all eyes. Incidence of severe resorption with extrusion of cylinder/requiring lamina removal was noted to be higher among patients with SJS.


Among the different types of keratoprostheses, the modified osteo-odonto-keratoprosthesis (MOOKP), which uses autologous tooth as a carrier for the polymethylmethacrylate optic, has shown promising long-term functional and anatomic results. We published the results of our initial experience with 50 cases in the year 2010. Among the various complications following any keratoprosthesis surgery, one of the concerns specific to the modified osteo-odonto-keratoprosthesis procedure is the process of resorption of the osteo-odonto alveolar lamina, which can lead to cylinder instability, aqueous leak, retroprosthetic membrane formation, and, in the worst cases, endophthalmitis and extrusion of the cylinder based on the severity of resorption. Previous studies have highlighted laminar resorption rates that range from 0% to 28%. Falcinelli and associates have recorded the least resorption over the longest follow-up. Liu and associates have reported a resorption rate of 19% over a mean follow-up of 3.9 years. Histopathologic examination of extruded laminae in a few cases has revealed evidence of chronic inflammation.


Radiologic imaging of the lamina by a spiral computed tomography (CT) scan can help assess the lamina qualitatively and quantitatively. Liu and associates have highlighted the importance of serial 3-D CT scans and a method of volumetric analysis in which 60% of patients had varying grades of resorption not noted clinically. Clinical diagnosis of resorption was noted to be difficult owing to the overlying mucous membrane graft. Severe resorption threatening the integrity of the lamina needs a second lamina to replace the resorbed one. This study describes the clinical features of laminar resorption, their modes of presentation, and their outcomes in 85 eyes over 10 years.


Methods


This retrospective case series included 85 eyes of 82 patients who underwent all stages of the modified osteo-odonto-keratoprosthesis procedure between March 10th, 2003 and March 31st, 2013. Cases that showed evidence of resorption clinically and/or radiologically were further studied. The approval of the Institutional Review Board of Vision Research Foundation, Chennai, India, was obtained for this study, which adhered to the tenets of the Declaration of Helsinki.


Patients


Following appropriate patient selection, the technique for performing the modified osteo-odonto-keratoprosthesis surgery was broadly based on the guidelines laid down in the Rome-Vienna protocol. The procedure was performed in 3 stages. In the first stage, an intracapsular cataract extraction was performed along with total iridectomy and limited anterior vitrectomy. In the second stage the osteo-odonto alveolar lamina was fashioned from the canine (maxillary/mandibular) and placed in a subcutaneous pouch in the cheek beneath the contralateral eye. Buccal mucous membrane was draped over the ocular surface and secured to the recti muscles. In the final stage, the lamina was removed from the subcutaneous pouch and placed on the eye after reflecting the mucosa. The mucosal flap was replaced over the lamina and a central opening was made for the cylinder to protrude through.


Lamina Preparation


Following a thorough preoperative dental evaluation by the maxillofacial surgeon and radiologic evaluation of the teeth, the canine tooth (maxillary/mandibular) was harvested, preserving as much of the periosteum as possible. This was then fashioned into the osteo-odonto alveolar lamina using the blades loaded onto the sagittal saw and oscillating saw handpiece attached to the drill machine (Stryker TPS Irrigation Console, Stryker India Pvt Ltd., USA). The micro core drill handpiece was used to drill the hole within the dentine slightly eccentric to the side with more bone. The preselected polymethylmethacrylate optical cylinder based on the axial length of the eye was glued into the central hole using bone cement (Stryker Surgical Simplex P-radiopaque bone cement, Stryker India Pvt Ltd., USA). Care was taken to remove any excess of acrylic cement. The dimensions of the lamina at the time of preparation are documented in Table 1 .



Table 1

Clinical Features in Eyes With Laminar Resorption Following Modified Osteo-odonto-keratoprosthesis Procedure


























































































































































































































































































































































































































SNo Age/Sex Etiology BCVA Presenting Feature Duration Since MOOKP (mo) Comments/Lamina Dimensions at the Time of Preparation (in mm)
1 46/M SJS 20/20 – CT scan-resorption STQ 48 – Steroid-antibiotic
– Vitritis 60 – Steroid-antibiotic
– RPM 65 – Membranectomy (12.4 x 9.2 x 3.5)
2 40/F SJS 20/40 – ? increased protrusion of cylinder 36 – Observe
– Vitritis
44 – Steroid-antibiotic
– Mobility of cylinder 46
– Extrusion 47 (14.9 x 9.3 x 3.4)
3 23/M SJS 20/30 – Vitritis 29 – Steroid-antibiotic
– Increased protrusion of cylinder 32 – Observe
– CT scan-early resorption
– Vitritis
– Vitritis 37 – Steroid-antibiotic
– CT scan – no bone superiorly 74 – Steroid-antibiotic (15 x 11 x 3.5)
4 20/M SJS 20/20 – Vitritis 36 – Steroid-antibiotic
– Mobility of cylinder 38
– CT scan-superior resorption (12.5 x 10.4 x 3.0)
5 53/M SJS 20/20 – Extrusion 60 (13.8 x 10.9 x 3.9)
6 23/F SJS 20/20 – Vitritis 32 – Steroid-antibiotic
– CT scan – superior resorption
– Aqueous leak 34 – New lamina prepared and replaced (15.6 x 7 x 3.7)
(2nd lamina) 20/30 – Vitritis 13 – Steroid-antibiotic
– Aqueous leak 14 – Lamina removal +VR procedure (15 x 8 x 3.4)
– RD
7 37/F SJS 20/20 – Mobility of cylinder 19 – Lamina removed
– Aqueous leak (14.7 x 9.6 x 3.3)
8 32/M SJS 20/20 – Endophthalmitis 48 – Lamina removed/resorption and leak noted superiorly intraoperatively (14.5 x 9 x 3)
9 20/F SJS 20/20 – Endophthalmitis 56 – Evisceration (13 x 9 x 3.4)
10 50/M SJS 20/20 – Recurrent vitritis 36 – Steroid-antibiotic
– Aqueous leak 60 – Lamina removed (12 x 9.5 x 3.2)
55/M (other eye) 20/20 – Vitritis 28 – Steroid-antibiotic
– Aqueous leak/RD 36 – Lamina removed (12.6 x 12.1 x 3.9)
11 37/M Multiple graft failure post RD surgery with silicone oil 20/600 – Extrusion 9 – Pressure necrosis by silicone oil cyst noted intraoperatively (15.3 x 9.7 x 4)
12 23/M Chemical 20/30 – Increased protrusion 60 – Observe (15 x 9.1 x 3)
– CT scan superior resorption 84
– ? aqueous leak
13 23/M Chemical 20/20 – Vitritis 66 – Steroid-antibiotic
– CT scan superior resorption 77 (12 x 10 x 3)
14 23/M Chemical 20/30 – Vitritis ? trauma 27 – Steroid-antibiotic
– Vitritis 48 – Steroid-antibiotic
– Extrusion 56 (12.7 x 10 x 3.5)
15 30/M Chemical 20/20 – CT scan early superior resorption 48 – Observe (13.7 x 11.6 x 3.4)
16 29/M Chemical 20/20 – Trauma 30 – Larger cylinder replaced
– cylinder mobility
– Aqueous leak 48 – Kpro exchange (12.6 x 10 x 3.4)
17 35/M Chemical 20/20 – Trauma 28 – New lamina replaced
– cylinder mobility (13.4 x 10 x 3.2)
(2nd lamina) 20/20 – Downward tilt 24 – Observe
20/120 – Large submucosal cyst 30 – Cyst communicating with globe noted intraoperatively (14 x 11 x 3.3)
– RD 43

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Jan 8, 2017 | Posted by in OPHTHALMOLOGY | Comments Off on Laminar Resorption in Modified Osteo-odonto-keratoprosthesis Procedure: A Cause for Concern
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