Abstract
Abstract: :
Background: OOKP is recommended for patients with end–stage ocular surface disease where conventional corneal grafts are known to fail. Originally described by Strampelli, present success of the operation is due to the modifications introduced by Falcinelli. The prostheis is fashioned from the patient’s canine tooth to create a biological frame to support a central PMMA optic. In the United Kingdom, newer optical cylinders have been designed (CL and CH). Purpose: To compare the gain of functional vision with different optic designs used for OOKP surgery in Brighton, UK. Method: Patients records were reviewed and further details regarding refractive error, quality of vision, extent of visual field and subjective assessment of change in quality of life were determined as and when they came for follow up (RT). Results: From Nov 1996 to Sept 2002, 28 patients had OOKP surgery done (CL and JH). All, except one, were practically blind in both eyes and all had surgery done in only one eye. Ten (Group A) had received the traditional optical cylinder. Eighteen had the new cylinders of which 16 (Gp B) had Design 1 and 2 (Gp C) had Design 2 . The age at surgery and number of blind years before the operation were similar between the groups. Follow up ranged from 3.75 to 6 yrs (Gp A), 1–3.75 yrs (Gp B) and 8 months – 1.5yrs (Gp C). Mean best vision recorded was 0.48 for Gp A, 0.63 for GpB and 0.4 for Gp C. Post–operative refraction ranged from –0.75 to +12D (median +2.75) for Gp A and –2.5 to +10D (median +1.75) for Gp B. The average visual field was 55 0 horizontally and 520 vertically for Gp A; 820 and 760 respectively for Gp B and 700 and 600 for Group C. Two patients in Gp A and one in Gp B required OOKP reversal. One patient each in Gp A and B developed endophthalmitis 2.5yrs after surgery and both had evidence of bone resorption. Raised IOP was prevalent in 70% patients in Gp A and 63% in Gp B and in both patients in Gp C. Eight patients (80%) in Gp A and 12 (70%) in Gp B and both patients in Gp C gained useful vision. Of the patients who could be interviewed, 100%, 91% and 100% in Gp A, B and C respectively expressed satisfaction with the visual result and confirmed a change in their quality of life. Those who did not gain vision had optic atrophy or retinal degeneration. Conclusions: OOKP helps rehabilitate blind patients with end–stage ocular surface disease towards achievement of their visual potential. The new designs provide better fields. Patient satisfaction is good with all 3 types of cylinders.
Keywords: keratoprostheses • optical properties • visual fields