PubMed · 9715021
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P R Chatterjee, H Datta. 1998. Refractive corneal surgery.. https://pubmed.ncbi.nlm.nih.gov/9715021/
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Non-invasive confocal biomicroscopy revealed regeneration of corneal nerve fibres coincident with corneal epithelial healing in a patient with neurotrophic keratopathy.
BACKGROUND: The aim of this study was identification of predictive factors for postoperative visual acuity in patients with a clear organ-cultured graft and to analyze the change in visual acuity between 12 and 24 months after transplantation. METHODS: The study design was a prospective cohort study. A total of 342 consecutive penetrating keratoplasties using donor organ-cultured grafts, performed in 324 patients, were included. Visual acuity, graft thickness, and graft endothelial cell density were recorded in patients with clear transplants. RESULTS: At 24 months postoperatively, 25 (18.7%) of 134 patients had 20/200 or worse visual acuity and 66 (49.3%) had 20/40 or better visual acuity. Graft thickness took 1 month to decrease to normal values. A temporary graft thinning occurred at 6 months postoperatively, followed by recovery of normal graft thickness by 18 months. The average postoperative endothelial cell density was 1,533+/-598 cells/mm2 during the second year. The 24-month LogMAR (logarithm of minimal angle of resolution) visual acuity correlated with preoperative LogMAR visual acuity (beta=0.26, P=0.005), postoperative lens status (beta=-0.34, P=0.008), preoperative intraocular pressure (beta=0.50, P=0.020), and postoperative astigmatism (beta=0.17, P=0.040). Visual acuity (P=0.022) significantly improved between 12 and 24 months. Preoperative diagnosis (P < 0.0001) and postoperative lens status (P < 0.0001) significantly influenced the change in LogMAR visual acuity between 12 and 24 months. CONCLUSIONS: Donor variables do not influence the visual acuity results of penetrating keratoplasty using organ-cultured donor tissue, whereas they have a strong influence on graft survival and graft endothelial cell density. Visual acuity improves during the first 2 years after transplantation. After keratoplasty, organ-cultured corneal grafts undergo dramatic modifications of their thickness and probably of their transparency.
OBJECTIVE: To compare the reproducibility of measurements obtained with a new pachymetry instrument, the Topcon specular microscope (Topcon SP-2000P; Topcon America Corp, Paramus, NJ), with those obtained by ultrasound pachymetry. METHODS: Corneal thickness was measured in 40 eyes of 40 patients 3 times each with the Topcon SP-2000P and an ultrasound pachymeter (DGH 500, DGH Technology Inc, Exton, Pa) by 2 separate investigators. Comparisons included average thickness as measured by each instrument, average thickness for each instrument as measured by each investigator, and differences in thickness due to corneal abnormalities. RESULTS: Mean corneal thickness measured by the Topcon instrument was significantly less (32 microm; P<.001) than the mean value obtained with the ultrasound pachymeter. Similarly, mean values obtained with the 2 instruments by the 2 investigators were significantly different (P<.001 and .008 for investigators 1 and 2, respectively), with the Topcon value less than the ultrasound value in both cases. Both instruments detected abnormalities in corneal thickness equally well. However, the measurements obtained with the Topcon instrument by the 2 investigators were more consistent (no significant difference [P=.32]) than those obtained with the ultrasound unit (difference was significant [P=.02]). CONCLUSIONS: The new noncontact Topcon specular microscope provides measurements of corneal thickness that are somewhat less than those of ultrasound pachymetry, but that seem to be more consistent from one operator to another, possibly as a result of the elimination of observer bias induced by probe placement required by the ultrasound unit. This consistency may be important in the comparison of measurements by different operators over time in patients being followed up after refractive surgery or other therapeutic interventions.