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C.M. Birt, V. Pathak–Ray, P. Kertes, C. Schwartz; Optic Nerve and Retinal Nerve Fibre Layer Morphology After Panretinal Photocoagulation – A Pilot Project With Results at Three Months . Invest. Ophthalmol. Vis. Sci. 2005;46(13):350.
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© ARVO (1962-2015); The Authors (2016-present)
Aim We wish to demonstrate a quantitative change, or lack of it, in the optic nerve head morphology as a result of panretinal photocoagulation undertaken for proliferative diabetic retinopathy. Methods: Patients were recruited prospectively; only those eyes which had not received any laser before were included. Patients underwent a Heidelberg Retinal Tomograph (HRT) at baseline ie just before they received PRP (three observations, 5 minutes apart); it was repeated at 3 months after conclusions of laser treatment (two observations, 5 minutes apart). Optical Coherence Tomography (OCT) was also done prior to and 3 months after the conclusions of laser treatment. The later observations were then compared to baseline to reach a conclusion at this early stage. Further observations are planned at a year post laser. Results: 11 eyes of 9 consecutive patients were recruited; three right eyes and four left eyes of six patients had their 3–month follow up completed. Mean number of laser burns delivered was 2003 over 3.85 sessions. Mean pre–laser disc area was 2.22 mm2 (range 1.73–2.82, SD 0.41), cup area was 0.5 mm2 (range 0.03–1.11, SD 0.39) and rim area was 1.71 mm2 (range 1.31–2.72, SD 0.48). Mean RNFL thickness as obtained by the HRT pre–laser was 0.22 mm (range 0.13–0.27, SD 0.06). Pre laser RNFL thickness as obtained by the OCT was 132.21 microns (range 99–186.5, SD 31.86) with mean superior thickness being 159.07 microns (range 84–209, SD 44.85), nasal 86.43 microns (range 60–105.5, SD 17.74), inferior 161.64 microns (range 111–254.5, SD 45.56) and temporal 116.28 microns (range 53.5–189, SD 44.86). Post–laser observations were carried out at a mean of 3.71 months (range 3–5) and disc area was 2.22 mm2 (range 1.73–2.82, SD 0.41), cup area was 0.47 mm2 (range 0.04–1.07, SD 0.47) and rim area was 1.76 mm2 (range 1.21–2.71, SD 0.49). Mean RNFL thickness as obtained by the HRT post–laser was 0.25 mm (range 0.17–0.34, SD 0.07). Post laser RNFL thickness as obtained by the OCT was 137.64 microns (range 102–228, SD 44.03) with mean superior thickness being 165.28 (range 100.5–259.5, SD 53.22), nasal 89.36 (range 51–155.5, SD 33.62), inferior 165.86 (range 134.5–226, SD 41.5) and temporal 120.28 (range 60–230, SD 56.44). Due to the small sample size none of the paired samples reached statistical significance when analysed by the paired t test Conclusions: Though there was no statistically significant change in the optic nerve morphology and RNFL at this time point, serial observations are to be carried out which may reveal changes in future. To the best of our knowledge no such study has been attempted before.
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