Histopathology of epi-LASIK in eyes with virgin corneas and eyes with previously altered corneas

PURPOSE: To perform a histological analysis of free epithelial flaps that were intentionally created with an Epi-K epikeratome (Moria S.A.) during epi-LASIK in eyes with virgin corneas and eyes with previous corneal surgery or keratoconus. SETTING: Vissum-Instituto Oftalmológico de Alicante, Alicante, Spain. METHODS: This prospective and consecutive case series comprised 18 free flaps obtained from 18 patients. Twelve patients had virgin corneas, and 6 had altered corneas from previous surgery, trauma, or keratoconus. The flaps were fixed in 4% buffered formaldehyde (pH 7) for posterior histopathological analysis. Serial cuts of each flap were performed, and the sheets were stained with hematoxylin-eosin and periodic acid-Schiff. The main outcome measure was the histopathology of the corneal flaps. RESULTS: All flaps from virgin corneas consisted entirely of epithelium without residual stromal tissue or Bowman's layer. Histopathological analysis of the flaps after epi-LASIK in patients with previously altered corneas showed varying levels of stroma in all cases. CONCLUSION: Epi-LASIK with the Epi-K epikeratome effectively cleaved the epithelium from Bowman's layer in healthy corneas; however, when the integrity of Bowman's layer is compromised, epi-LASIK should be avoided as stromal invasion will likely occur.     

Evaluation and transplantation of corneas from pseudophakic donor eyes

PURPOSE: To evaluate the quality of corneal donor tissue from pseudophakic eyes for transplantation. METHODS: Only capsular-supported posterior chamber pseudophakia was studied. Forty-five pairs of donor eyes were assessed and evaluated by standard Minnesota Lions Eye Bank (MLEB) protocol. Thirty-three pairs were unilaterally pseudophakic with the unoperated phakic eye used as a control eye. Twelve donors were bilaterally pseudophakic. All corneas were rated for corneal clarity, epithelial defects, stromal edema, Descemet's membrane folding, endothelial cell density (ECD), and cell damage by slit-lamp examination and specular microscopy. If the corneas were not transplanted, the endothelium was vital stained with trypan blue and counterstained with alizarin red S for quantitation, localization, and visualization of cell morphology and damage. RESULTS: Sixty-eight of the 90 corneas in this study did not meet transplantation criteria. A significant difference in ECD (>22%) and in overall corneal rating was found in seven (21%) of 33 pairs of unilateral pseudophakic donors. Fourteen corneal transplants were performed using corneas from the donors in this study. Nine corneas from pseudophakic donor eyes were transplanted, resulting in one primary graft failure reported. CONCLUSION: Corneas from pseudophakic donor eyes may need more extensive evaluation for endothelial viability than is currently required by eye bank standards.     

Tonometry in normal and scarred corneas, and in postkeratoplasty eyes: a comparative study of the Goldmann, the ProTon and the Schiotz tonometers

PURPOSE: Clinical comparison of intraocular pressure (IOP) measured with the Goldmann applanation tonometer (GAT), the ProTon tonometer (PT), and the Schiotz tonometer (ST), in normal eyes, eyes with scarred corneas and postkeratoplasty eyes. MATERIAL AND METHODS: The IOP readings with GAT, PT, and ST were compared in 125 eyes with normal corneas (Group A), 17 eyes with scarred corneas (Group B), and in 21 postkeratoplasty eyes (Group C). The data were statistically analysed at 95% confidence interval; linear regression analysis and paired t-test were done. RESULTS: The mean differences and their standard deviation [SD] between GAT and PT readings, and GAT and ST readings respectively were: [1] in Group A: -0.23 [SD 2.75] mmHg and +0.24 [SD 3.18] mmHg respectively; [2] in Group B: -1.8 [SD 12.67] mmHg and -4.5 [SD 9.95 mmHg; and [3] in Group C: +0.24 [SD 8.72] mmHg and -0.12 [SD 8.7] mmHg. They were not statistically significant. In Group A the 95% confidence interval between GAT and PT readings was -5.27 mmHg to 5.73 mmHg, and between GAT and ST readings, -6.12 mmHg to 6.59 mmHg. Ninety six [77%] eyes with the PT and 84 [69%] eyes with ST measurements were within 3 mmHg of GAT pressure. The correlation coefficients [r] for PT and ST were 0.93 [P = 0.0000] and 0.88 [P = 0.0000] respectively. In Group B 95% confidence interval between GAT and PT readings was -27.17 mmHg to 23.51 mmHg, and between GAT and ST measurement, -24.37 mmHg to 15.44 mmHg. The correlation coefficients [r] for the PT and ST were 0.112 [P = 0.660] and 0.630 [P = 0.006] respectively. In group C, the 95% confidence interval between GAT and PT measurements was -17.20 mmHg to 17.67 mmHg, and between GAT and ST measurements, -17.51 mmHg to 17.27 mmHg. The correlation coefficients [r] for the PT and the ST were 0.780 [P = 0.0000] and 0.740 [P = 0.0001] respectively. CONCLUSIONS: In clinical practice PT appears to have a higher level of accuracy than ST in normal corneas. In scarred corneas and post-penetrating keratoplasty eyes, because of high SD for mean differences and wide confidence interval of 95%, both PT and ST are inaccurate in measuring IOP as compared to GAT in such eyes.     

Long-term safety of laser in situ keratomileusis in eyes with thin corneas: 5-year follow-up

AIM: To investigate the long term (≥5y) efficacy, predictability, and safety of laser in situ keratomileusis (LASIK) in eyes with thin corneas [central corneal thickness (CCT) <500 μm]. METHODS: A total of 339 patients met the criteria of this study. Finally, 175 eyes of 89 patients who had thin corneas and underwent LASIK≥5y ago returned to our clinic and included in this study. Preoperative parameters recorded included uncorrected visual acuity (UCVA), corrected distance visual acuity (CDVA), manifest refraction, CCT and corneal topography. At returning visits, in addition to visual acuity and manifest refraction, ultrasound CCT and corneal topography were performed. Optical coherence tomography was used to measure the CCT, LASIK flap thickness, and residual stromal bed thickness (RSBT). Safety index, efficacy index, percentage of eyes within ±0.5 D and ±1.0 D of refraction, percent tissue altered (PTA), and percentage stromal bed thickness (PSBT) were calculated. RESULTS: The safety index was 1.09 and efficacy index was 0.99. The percentages of eyes within ±0.5 D and ±1.0 D were 71.2% and 87.7%, respectively. The mean PTA was 40%±6% (range 20% to 55%); 76 eyes (43.4%) had PTA <40% and 99 eyes (56.6%) had PTA≥40%. The mean RSBT was 303±27 μm (range 240 to 390 μm), and 2 eyes had RSBT<250 μm. The mean PSBT was 61%±9% (range 51% to 85%). No eyes developed ectasia. CONCLUSION: In this cohort with the PSBT of 50% or more, LASIK is safe with follow-up for at least 5y.     

Cyclodiode laser therapy for painful, blind glaucomatous eyes

AIMS: To determine the ability of cyclodiode laser treatment to relieve discomfort in painful blind glaucomatous eyes. METHODS: 30 eyes underwent cyclodiode to reduce intraocular pressure (IOP) and relieve pain. Patients graded their pre-cyclodiode and post-cyclodiode pain. RESULTS: After a minimum follow up of 6 months, a single cyclodiode treatment lowered mean IOP from 51 mm Hg (95% CI plus or minus 3.7 mm Hg) to 26 mm Hg (95% CI plus or minus 5.8 mm Hg) providing pain relief in 73.3% (22/30). After retreatment of six eyes, mean IOP was reduced to 22 (95% CI plus or minus 5.3) mm Hg and pain relief was obtained in 96.7% (29/30). For eyes achieving pain relief after one treatment, IOP was reduced by >30% in 81.0% (17/21). For eyes not achieving pain relief after one treatment, IOP was reduced by >30% in only 22.2% (2/9) (p=0.0042, Fisher's exact test). CONCLUSION: Cyclodiode was highly successful in providing pain relief in painful blind hypertensive glaucomatous eyes. The best predictor of successful pain relief was IOP reduction of > 30% from baseline.     

Acute retinal necrosis syndrome: analysis, therapy and long-term follow up of 14 eyes

PURPOSE: Acute retinal necrosis syndrome (ARN) might be complicated by retinal detachment, vasculopathy and optic neuropathy and has a poor prognosis despite intensive medical and surgical therapy. PATIENTS AND METHODS: A series of 10 consecutive patients (14 eyes) with ARN were followed for 36 months (average of 20 months +/- 10). We present the results of the clinical evaluation for diagnostic and therapeutic modalities. RESULTS: Viral etiology was confirmed in 9 of 10 aqueous-humor samples. Intraocular antibody synthesis against Varicella-Zoster Virus was found in 7, against Herpes-Simplex Virus in 5 and against Cytomegalovirus in 2 samples. Three eyes had a mild clinical course with a visual acuity of 0.6 or better. Vitrectomy and silicone-oil tamponade preserved visual acuity from 0.3 to 0.1. ARN lead to blindness in 5 eyes due to vasculopathy, optic neuropathy or retinal detachment. An arterial branch occlusion was successfully overcome with i.v. heparin treatment in one patient. CONCLUSION: Aqueous-humor analysis supports clinical diagnosis. Early vitrectomy and silicone oil tamponade stabilizes retinal structure and preserves visual acuity. Occlusive vasculopathy and optic neuropathy are the main causes leading to blindness.     

Refractive and visual outcomes of small incision lenticule extraction (SMILE) in eyes with thin corneas

ObjectivesTo report the refractive and visual outcomes of small incision lenticule extraction (SMILE) with the thinnest corneal thickness (CCT) of less than 500 µm and evaluate it in terms of safety and efficacy.SettingRefractive Surgery Clinic of University of Health Sciences Beyoglu Eye Training and Research Hospital, Istanbul, Turkey.DesignRetrospective case series.MethodsThe pre-and-postoperative examinations of all patients with thin corneas (preoperative CCT <500 µm) who underwent the SMILE procedure and had a minimum of 24 months of follow-up records were reviewed from medical files. The main outcome measures of the refractive and visual outcomes and the effect on corneal high order aberrations (HOAs) were evaluated.ResultsThe study included 55 eyes of 39 patients. The mean preoperative uncorrected visual acuity (UDVA) was 1.3 ± 1.5 logMAR, and the mean postoperative UDVA was significantly improved to 0.05 ± 0.80 logMAR at the last visit (p < 0.001). At the last follow-up, 84% of the eyes were within ± 0.50D, and 96% of the eyes were within ±1.00D of attempted SE refraction. The HOAs of coma (p < 0.001), secondary astigmatism (p = 0.015), spherical aberration (p < 0.001), and RMS (p < 0.001) aberrations increased significantly from the baseline to the postoperative last visit. The increase in trefoil was not significant (p = 0.32). No sight threatening complications or ectasia were observed during the follow-up time.ConclusionSMILE is a safe and effective technique with long-term stability for treatment of myopia in eyes with a thin cornea, and satisfactory results can be obtained if candidates for surgery are selected carefully with particular emphasis on normal preoperative corneal topography.Subject terms: Outcomes research, Refractive errors     

Comparison of iCare tonometer and Goldmann applanation tonometry in normal corneas and in eyes with automated lamellar and penetrating keratoplasty

Purpose

To compare intraocular pressure (IOP) measurements with Goldmann applanation tonometry (GAT) and iCare tonometry in normal and post-keratoplasty corneas and to assess the influence of central corneal thickness (CCT), corneal curvature (CC), and corneal astigmatism (CA) on IOP.

Methods

This prospective cross-sectional study included one eye of 101 subjects with normal corneas (58 healthy subjects, 43 glaucoma); and 90 post-keratoplasty patients: 34 penetrating keratoplasties (PK); 20 automated-lamellar-therapeutic keratoplasties (ALTK); 19 Descemet-stripping-automated-endothelial keratoplasties (DSAEK); 17 edematous grafts. All subjects underwent GAT and iCare IOP measurements in random order, and CCT, CC, and CA evaluation. The Bland–Altman method and multivariate regression analysis were used to assess inter-tonometer agreement and the influence of CCT, CC, and CA on IOP.

Results

iCare significantly underestimated IOP in all groups compared with GAT (GAT minus iCare of 3.5±3.5 mm Hg, P<0.001), but overestimated IOP in the edematous grafts (GAT minus iCare of −6.5±1.9 mm Hg, P<0.001). In normal corneas, both tonometer measurements were directly related to CCT values; iCare readings appeared inversely related to CC. There was no significant relationship between IOP and CCT, CC and CA in post-keratoplasty eyes, except between CC and iCare measurements for PK eyes.

Conclusions

The agreement between GAT and iCare was clinically acceptable in control, ALTK and DSAEK groups, and poor in PK and edematous grafts eyes. In normal corneas, GAT was significantly affected by CCT; iCare was influenced by CCT and CC. The iCare appeared less influenced by corneal edema when compared with GAT. High IOP readings taken with both tonometers in grafts should raise suspicion of true elevated IOP.     

Thick corneas,large pupils,and a giant problem

An 87-year-old woman presented 1 month after uneventful cataract surgery with ipsilateral corneal edema. She was diagnosed with pseudophakic bullous keratopathy and scheduled for endothelial transplantation. A few days later, however, she presented with bilateral corneal edema, dilated pupils, and further reduction of visual acuity. Neuro-ophthalmic evaluation disclosed a bilateral ocular ischemic syndrome causing complete visual loss. Temporal artery biopsy was consistent with giant cell arteritis. Corneal decompensation should be considered as a rare presentation of giant cell arteritis, a diagnosis that ophthalmologists should suspect in any case of unilateral or bilateral ocular ischemic syndrome.     

Human diabetic corneas preserve wound healing,basement membrane,integrin and MMP-10 differences from normal corneas in organ culture

The authors have previously documented decreased epithelial basement membrane (BM) components and alpha3beta1 epithelial integrin, and increased expression of matrix metalloproteinase (MMP)-10 in corneas of patients with diabetic retinopathy (DR) compared to normal corneas. The purpose of this study was to examine if organ-cultured DR corneas exhibited the same alterations in wound healing and diabetic marker distribution as the autopsy DR corneas. Twenty normal and 17 DR corneas were organ-cultured in serum-free medium over agar-collagen gel at the air-liquid interface for up to 45 days. Circular 5 mm central epithelial wounds were made with n-heptanol, the procedure that will preserve fragile diabetic corneal BM. Wound healing was monitored microscopically every 12 hr. Distribution of diabetic corneal epithelial markers including laminin-10 alpha5 chain, nidogen-1/entactin, integrin alpha3beta1, and MMP-10, was examined by immunofluorescence. Normal corneas healed the central epithelial defect within 3 days (mean=2.3 days), whereas DR corneas on average healed about two times slower (mean=4.5 days). In wounded and completely healed organ-cultured corneas, the patterns of studied markers were the same as in the unwounded organ-cultured corneas. This concerned both normal and DR corneas. As in vivo, normal organ-cultured corneas had continuous staining for laminin-10 and nidogen-1/entactin in the epithelial BM, strong and homogeneous staining for both chains of alpha3beta1 integrin in epithelial cells, and little if any staining for MMP-10. Organ-cultured DR corneas also had marker patterns specific for in vivo DR corneas: interrupted to no staining for laminin-10 and nidogen-1/entactin in the epithelial BM, areas of weak or disorganized alpha3beta1 integrin in epithelial cells, and significant MMP-10 staining in the epithelium and keratocytes. Fibrotic extracellular matrix and myofibroblast markers were largely absent. Thus, epithelial wound healing was much slower in organ-cultured DR corneas than in normal corneas, in complete accordance with clinical data in diabetic patients. DR corneas in organ culture preserved the same marker abnormalities as in vivo. The marker distribution was unchanged in wounded and healed organ-cultured corneas, compared to unwounded corneas. The established corneal organ culture provides an adequate system for elucidating mechanisms of epithelial alterations in human DR corneas.     

Reducing contamination when removing and storing corneas: a multidisciplinary, transversal, and environmental approach

PURPOSE: The combination of a shortage of cornea grafts in France and a national average contamination rate of 9% to 10%, has led us to search for the origins of this contamination. The objective of our study was to reduce the number of unusable grafts resulting from contamination of corneas in organ culture. METHODS: An external audit was carried out by an independent pharmacist on the removal conditions and treatment procedures for corneas. An environmental study was carried out, consisting of microbiological sampling of the corneas of donors who just died (<24 hours) as well as water and air samples in the premises used for removal. The Cornea Bank's procedures were submitted to a microbiological risk analysis using the "failure mode effects and criticity analysis" (FMECA) method. RESULTS: The critical contamination periods were found to be before removal, during mortuary washing and during decontamination of the conjunctival cul-de-sac at the removal stage. The corrective measures taken have reduced contamination rates by half in 1 year. CONCLUSION: Highlighting the sources of contamination has led to the implementation of effective targeted and low-cost measures that have allowed us to reduce significantly the number of cornea graft losses as a result of bacterial and fungal contamination.     

Tenascin-C expression in normal, inflamed, and scarred human corneas

AIMS/BACKGROUND—In adult tissues the expression of tenascin-cytotactin (TN-C), an extracellular matrix glycoprotein, is limited to tumours and regions of continuous renewal. It is also transiently expressed in cutaneous and corneal wound healing. There are limited data regarding its expression in inflammation and scarring of the adult human cornea. In this study, TN-C expression patterns in normal, inflamed, and scarred human corneas have been examined.
METHODS—Penetrating keratoplasty specimens were selected from cases of herpes simplex keratitis, herpes zoster ophthalmicus, rheumatoid arthritis ulceration, bacterial keratitis, rosacea keratitis, interstitial keratitis, and previous surgery so as to encompass varying degrees of active and chronic inflammation and scarring. TN-C in these and in normal corneas was immunodetected using TN2, a monoclonal antibody to human TN-C.
RESULTS—There was no TN2 immunopositivity in normal corneas except at the corneoscleral interface. In pathological corneas, TN2 immunopositivity was localised in and around regions of active inflammation, fibrosis, and neovascularisation. TN2 positivity was less in acute inflammation than in active chronic inflammation. Mature, avascular scar tissue and epithelial downgrowth were TN2 negative.
CONCLUSION—These results indicate that in the adult human cornea, TN-C expression is induced in regions of inflammation, fibrosis, and neovascularisation, but that expression is absent in mature, avascular scar tissue. This suggests a role for this glycoprotein in inflammation, healing, and extracellular matrix reorganisation of the cornea.

     

Proteinase and growth factor alterations revealed by gene microarray analysis of human diabetic corneas

PURPOSE: To identify proteinases and growth factors abnormally expressed in human corneas of donors with diabetic retinopathy (DR), additional to previously described matrix metalloproteinase (MMP)-10 and -3 and insulin-like growth factor (IGF)-I. METHODS: RNA was isolated from 35 normal, diabetic, and DR autopsy human corneas ex vivo or after organ culture. Amplified cRNA was analyzed using 22,000-gene microarrays (Agilent Technologies, Palo Alto, CA). Gene expression in each diabetic corneal cRNA was assessed against pooled cRNA from 7 to 9 normal corneas. Select differentially expressed genes were validated by quantitative real-time RT-PCR (QPCR) and immunohistochemistry. Organ cultures were treated with a cathepsin inhibitor, cystatin C, or MMP-10. RESULTS: More than 100 genes were upregulated and 2200 were downregulated in DR corneas. Expression of cathepsin F and hepatocyte growth factor (HGF) genes was increased in ex vivo and organ-cultured DR corneas compared with normal corneas. HGF receptor c-met, fibroblast growth factor (FGF)-3, its receptor FGFR3, tissue inhibitor of metalloproteinase (TIMP)-4, laminin alpha4 chain, and thymosin beta(4) genes were downregulated. The data were corroborated by QPCR and immunohistochemistry analyses; main changes of these components occurred in corneal epithelium. In organ-cultured DR corneas, cystatin C increased laminin-10 and integrin alpha(3)beta(1), whereas in normal corneas MMP-10 decreased laminin-10 and integrin alpha(3)beta(1) expression. CONCLUSIONS: Elevated cathepsin F and the ability of its inhibitor to produce a more normal phenotype in diabetic corneas suggest increased proteolysis in these corneas. Proteinase changes may result from abnormalities of growth factors, such as HGF and FGF-3, in DR corneas. Specific modulation of proteinases and growth factors could reduce diabetic corneal epitheliopathy.     

青光眼的基因治疗:问题与挑战

青光眼基因治疗的靶目标包括眼前节的小梁网和睫状体、眼后节的视网膜神经节细胞等。青光眼基因治疗的策略包括降眼压、视神经保护及抑制滤过术后瘢痕形成等方面。将目的基因导入小梁组织使房水排出阻力增加是一种理想的造模方法。目前虽在青光眼基因治疗领域取得较大进展,但在组织特异性启动子、长时基因表达及副作用等方面尚存在着问题和挑战。     

Simultaneous laser in situ keratomileusis on the stromal bed and undersurface of the flap in eyes with high myopia and thin corneas

PURPOSE: To evaluate simultaneous laser in situ keratomileusis (LASIK) on the stromal bed and the undersurface of the flap in eyes with high myopia and insufficient corneal thickness for conventional LASIK ablation. SETTING: 21 Century Eye Hospital, Seoul Paik Hospital, Inje University, Seoul, Korea. METHODS: Using intraoperative pachymetry, the residual stromal bed thickness was evaluated and simultaneous LASIK was performed on the stromal bed and undersurface of the flap without compromising the posterior 300 mum of the stromal bed. In a prospective series, outcomes in 43 eyes of 27 patients with mean spherical equivalent refraction ranging from -12.5 to -3.75 diopters were analyzed 1, 3, and 6 months after surgery. RESULTS: Postoperative uncorrected visual acuity was 20/30 or better in 35 eyes (81.4%) at 1 month, 36 eyes (83.7%) at 3 months, and 34 eyes (79.1%) at 6 months. During surgery and follow-up, no vision-threatening complications occurred. CONCLUSION: Simultaneous LASIK appears to be a useful surgical aid in LASIK treatment in eyes with high myopia with or without astigmatism when an adequate residual stromal bed does not exist.     

Deposits in artificial corneas: risk factors and prevention

PURPOSE: To identify risk factors for calcium deposition and pigmented staining within AlphaCor artificial corneas. METHODS: Retrospective analysis of data from 72 AlphaCor implantations was conducted. Histological analysis of explants was performed. RESULTS: Eight cases of either intraoptic calcium or pigment deposition occurred in AlphaCor patients between 2.5 and 21 months after implantation. Four cases had diffuse white deposits, confirmed to be calcium and associated with prior coadministration of topical steroids and beta-blockers. The other four cases had brown deposits, associated with cigarette smoking and topical levobunolol. CONCLUSION: These findings led to changes in patient management protocols, surgeon training and patient information so as to minimize the risk of further occurrences. No further cases of white deposition have occurred after warning surgeons of the risk associated with certain topical therapy combinations. The risk of brown staining may be difficult to remove completely as it appears that environmental exposure to chemicals may cause deposition in addition to personal smoking habits and topical medications.     

Distribution and some properties of cathepsin B in the bovine eyes.

Cathepsin B in the bovine eye was studied biochemically using α-N-benzoyl-l-arginine amide as substrate. The highest specific activity of cathepsin B was observed in the ciliary body among bovine eye tissues, the activity being highest in the lysosomal fraction. The optimal pH of the enzyme in the ciliary body was about 5·1. The enzyme activity in the ciliary body was activated by thiol agents, and inhibited by p-chloromercuribenzoate, leupeptin and heavy metal ions.     

Characteristics of frequency-of-seeing curves for a motion stimulus in glaucoma eyes, glaucoma suspect eyes, and normal eyes.

This study compared frequency-of-seeing curves for a line displacement test in glaucoma patients and normals. Probit analysis of the frequency-of-seeing curves provided the motion thresholds and the slopes of the frequency-of-seeing curves, represented by the interquartile range. The thresholds and interquartile ranges were significantly elevated in the glaucoma eyes and suspect eyes, compared to controls. A logistic regression model incorporating both the interquartile range and threshold significantly improved the sensitivity of the motion test in the suspects. Abnormal shallowing of the slope of the motion frequency-of-seeing curve may represent one of the earliest changes in glaucoma.