Corneal subbasal nerve fiber regeneration in myopic patients after laser in situ keratomileusis

A total of 26 myopic patients （52 eyes） underwent laser in situ keratomileusis. In vivo confocal microscopy revealed that most of the regenerated corneal subbasal nerve fibers in the comeal flap originated from the stump of corneal subbasal nerve fibers outside the ablation zone and extended towards the center of the cornea in all patients. Meanwhile, new fibers were also found to directly regenerate from deep in the stroma in some cases. Approximately 94% of regenerated corneal subbasal nerve fibers （73/78 eyes） regrew vertically into the peripheral central 6-mm circle area 1 month after surgery, 78% （28/36 eyes） grew into the central 3 6 mm area at 2 months, and 23% into the central 3-mm circle area at 3 months. In addition, there was no significant difference in corneal subbasal nerve fiber regenerative capacity between the basic fibroblast growth factor group and the 20% （vN） deproteinized extract of calf blood group. The majority of corneal subbasal nerve fiber regeneration occurred from the stump of corneal subbasal nerve fibers outside the corneal flap and the remaining growth occurred deep within the stroma.

Clinical observation of recombinant human nerve growth factor in the treatment of neurotrophic keratitis

AIM:To characterize changes of corneal nerve morphology and tear indices in patients with neurotrophic keratitis(NK)treated with recombinant human nerve growth factor(rhNGF).METHODS:In a prospective observational study,six patients(nine eyes)were locally treated with rhNGF.Visual acuity,corneal fluorescein staining score,the heights of the tear river,lipid layer thickness(LLT),tear ferning(TF)test,conjunctival impression cytology(CIC)examination,the densities of cornea subbasal nerve fibers were determined before and after treatment.RESULTS:Compared with baseline,there was a significant difference in corneal fluorescence staining scores(P<0.01);all patient corneal epithelial defects recovered completely within 8wk,but there was no significant improvement in the height of the tear river(P=0.202).LLT was significantly increased when compared with baseline(P=0.042);however,the function of conjunctival goblet cells and mucin content did not significantly improve using the TF test and CIC examination(P=0.557,P=0.539).After 8wk of treatment,the average corneal subbasal nerve fiber density increased significantly(P<0.01),as did the number of corneal nerve fiber branches(P=0.001).CONCLUSION:RhNGF can increase the density of corneal subbasal nerve fibers,promote the healing of persistent corneal epithelial defects and corneal ulcers in patients with NK,also improving tear function partially.

Changes in corneal innervation and pain responses in fungal keratitis

AIM: To characterize changes in the cornea nerve and pain responses in fungal keratitis(FK).METHODS: A retrospective analysis of in vivo confocal microscopy images of 11 FK corneas was performed, and the results were compared with those for 11 normal corneas. Subbasal corneal nerves were analyzed for total nerve number, main nerve trunk number, branching patterns and tortuosity. C57 BL/6 mice were infected with Aspergillus fumigatus. Disease severity was determined through clinical scoring and slit lamp photography. Corneas were harvested at 1, 3, 5, and 7 d post infection(p.i.) and assessed for β III tubulin. Corneal mechanical sensitivity thresholds were detected by von Frey test. β-endorphin(β-EP) and μ receptor protein expression was detected through Western blotting.RESULTS: Total nerve number, main nerve trunk number, and nerve branching were significantly lower in FK patients than in controls, but tortuosity was not significantly different. In infected mice, subbasal nerve density decreased from 1 d p.i., reaching a minimum at 5 d p.i. Clinical scores rose at 1 d p.i., peaked at 3 d p.i., and decreased at 5 d p.i. Mechanical sensitivity thresholds showed the same trends. β-EP and μ receptor protein expression increased after infection.CONCLUSION: Corneal nerve density is lower in FK patients and Aspergillus fumigatus-infected mice than in controls. Pain sensitivity decreases with postinfection corneal ulcer aggravation. β-EP and μ receptor proteins are both upregulated in infected mouse corneas.

Ocular surface evaluation in eyes with chronic glaucoma on long term topical antiglaucoma therapy

AIM： To evaluate ocular surface changes and its correlation with the central corneal subbasal nerve fibre layer in chronic glaucoma patients. METHODS： A prospective comparative study of ocular surface evaluation was performed in 50 eyes of 25 patients using two or more antiglaucoma medications for at least 6too and 50 eyes of 25 normal subjects without any ocular problems as controls. The study parameters evaluated included visual acuity, intraocular pressure, ocular surface evaluation parameters [fluorescein break-up time （FTBUT）, Schirmer＇s I test, ocular surface staining scores and ocular surface disease index score （OSDI）], central corneal sensation （Cochet Bonnett aesthesiometer）, central subbasal nerve fiber layer density （SBNFLD） by confocal microscopy. RESULTS： The mean values in the glaucoma cases and control groups respectively were as follows： OSDI score （35.89±16.07/6.02±3.84; P=-0.001）, Schirmer＇s I test score （7.632.64 mm/12.86±1.93 mm; P=-0.001）, FTBUT （9.442.76s/11.8±1.88s; P=0.001）, corneal （5.7±2.33/ 1.1±0.58; P=0.001） and conjunctival staining score （5.061.94/0.84±0.46; P=0.001）, corneal sensitivity （4.68±0.44/5.07±0.37; P=0.076）, mean subbasal nerve fiber number （3.58±0.99/5.40±1.70; P=0.001）, SBNFL length （1101.44±287.56 pm/1963.70±562.56 pro; P=0.001） and density （6883.941798.03 pm/mm/12 273.153516.04 pm/mm2; P=O.O01）. Dry eye severity of level 2 and 3 was seen in 66% of glaucoma group. Corneal （/=0.86） and conjunctival staining （R2=0.71） and OSDI score （R=0.67） showed statistically significant negative correlation with central corneal SBNFLD while FTBUT （R==0.84）, corneal sensitivity （/=0.52） showed positive correlation to central corneal SBNFLD in the long term topical antiglaucoma medication group. CONCLUSION： Ocular surface changes and antiglaucoma therapy induced dry eye is found to be associated with decreased SBNFLD in eyes on long term topical antiglaucoma medications.