PubMed · 13556830
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R DAY. Artificial corneal implants.. https://pubmed.ncbi.nlm.nih.gov/13556830/
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OBJECTIVE: To assess the usefulness of corneal esthesiometry for screening diabetic retinopathy. METHODS: A cross-sectional study was carried out comprising 575 patients attending a diabetic retinopathy-screening program in the city of São Paulo. Corneal esthesiometry was assessed with the Cochet-Bonnet esthesiometer. The presence of diabetic retinopathy was detected with indirect fundoscopy. The validity of corneal esthesiometry in identifying diabetic retinopathy was evaluated by the Receiver Operating Characteristic (ROC) curve. RESULTS: Sensitivity and specificity analyses of the corneal esthesiometry for detecting the stages of diabetic retinopathy using different cut-offs showed values less than 80%. The best indices (72.2% sensitivity and 57.4% specificity) were obtained for the identification of patients with proliferative diabetic retinopathy. CONCLUSIONS: In the study series, corneal esthesiometry was not a good indicator of diabetic retinopathy.
AIMS/HYPOTHESIS: The accurate detection, characterization and quantification of human diabetic neuropathy are important to define at risk patients, anticipate deterioration, and assess new therapies. Corneal confocal microscopy is a reiterative, rapid, non-invasive in vivo clinical examination technique capable of imaging corneal nerve fibres. The aim of this study was to define the ability of this technique to quantify the extent of degeneration and regeneration of corneal nerve fibres in diabetic patients with increasing neuropathic severity. METHODS: We scanned the cornea and collected images of Bowman's layer (containing a rich nerve plexus) from 18 diabetic patients and 18 age-matched control subjects. RESULTS: Corneal nerve fibre density (F(3)=9.6, p<0.0001), length (F(3)=23.8, p<0.0001), and branch density (F(3)=13.9, p<0.0001) were reduced in diabetic patients compared with control subjects, with a tendency for greater reduction in these measures with increasing severity of neuropathy. CONCLUSION/INTERPRETATION: Corneal confocal microscopy is a rapid, non-invasive in vivo clinical examination technique which accurately defines the extent of corneal nerve damage and repair and acts as a surrogate measure of somatic neuropathy in diabetic patients. It could represent an advance to define the severity of neuropathy and expedite assessment of therapeutic efficacy in clinical trials of human diabetic neuropathy.
OBJECTIVE: To assess the alterations in human donor corneal tissue induced by Q-switched erbium (Er):YAG laser corneal trephination. METHODS: Thirty human corneoscleral donor buttons unsuitable for transplantation were placed in an artificial chamber on an automated rotation device. Corneas were trephined with a Q-switched Er:YAG laser (wavelength, 2.94 microm; pulse duration, 400 nanoseconds) along (donor and recipient) aluminum silicate (ceramic) open masks. A spot diameter of 0.65 mm, energy setting of 50 mJ/pulse, and repetition rate of 5 Hz were used. Corneal thermal damage and cut regularity were quantitatively assessed in 24 corneas processed for light microscopy and by transmission and scanning electron microscopy. RESULTS: The stromal thermal damage was the highest (mean [SD], 8.0 [2.7] microm) at a 150-microm cut depth and decreased downward. Cut regularity was very good and did not significantly differ between donors and recipients. Scanning electron microscopy confirmed that the cuts were highly regular; transmission electron microscopy revealed 2 distinctive subzones within the stromal thermal damage zone. CONCLUSIONS: Thermal damage induced by Q-switched Er:YAG nonmechanical corneal trephination was low, and the regularity of the cuts was very good. CLINICAL RELEVANCE: The Q-switched Er:YAG laser may have the potential to become an alternative to the excimer laser for nonmechanical penetrating keratoplasty.