Safety threshold of intravitreal clonidine in rabbit’s eyes

AIM: To determine the safe dose of intravitreal clonidine (IVC), a potential drug for neuroprotection and angiogenesis inhibition in rabbits. METHODS: A total of 28 rabbits were divided into four groups. Three groups received IVC with concentrations of 15 (Group A), 25 (Group B), and 50 (Group C) μg/0.1 mL and the control group (Group D) received 0.1 mL balanced salt solution (BSS). To investigate IVC safety, electroretinography (ERG) was performed at baseline, then at 1, 4 and 8wk after injection. After last ERG, all rabbits were euthanized, their eyes were enucleated and subjected to routine histopathological evaluation, immunohistochemistry for glial fibrillary acidic protein (GFAP) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) test. RESULTS: Based on ERG, histopathology, GFAP and TUNEL assay findings, 15 μg IVC was determined as the safe dose in rabbit eyes. While, the results of routine histopathology and TUNEL assay were unremarkable in all groups, toxic effects attributed to 25 and 50 μg IVC were demonstrated by ERG and GFAP tests. CONCLUSION: Totally 15 μg clonidine is determined as the safe dose for intravitreal injection in rabbits. Contribution of IVC in neuroprotection and inhibition of angiogenesis deserve more studies.     

Laser photocoagulation of eyes with drusen: will It help?

Drusen are deposits located deep in the sensory retina that are seen characteristically in eyes with macular degeneration (AMD). As multiple large drusen are a risk factor for the development of visual loss from AMD, laser strategies to cause drusen to resorb have been devised. Two large, randomized controlled trials using laser photocoagulation prophylactically for the treatment of AMD are underway to determine the efficacy of such treatment.     

Cryolite glass prosthetic eyes—the response of the anophthalmic socket

Graefe's Archive for Clinical and Experimental Ophthalmology - To investigate mucoid discharge and the inflammatory response of anophthalmic sockets to cryolite glass prosthetic eye wear. A...     

Transforming growth factor-β2 levels in aqueous humor of glaucomatous eyes

PURPOSE: To determine whether clinical characteristics are correlated with increased levels of transforming growth factor-beta 2 (TGF-beta 2) in aqueous humor in glaucomatous eyes. METHODS: Aqueous humor samples were collected from 91 glaucomatous eyes. Included were samples from primary open-angle glaucoma (POAG) in 40 eyes, (pseudo)exfoliation syndrome (EXS) in 18 eyes, primary angle-closure glaucoma (PACG) in 26 eyes and uveitis-related secondary glaucoma (SG) in 7 eyes. TGF-beta 2 in aqueous humor was assessed with a specific-capture ELISA. RESULTS: The mean concentration (+/- standard error) of mature (biologically active) TGF-beta 2 in the aqueous humor of eyes with POAG was 293.6 +/- 33.6 pg/ml, significantly higher than that in eyes with PACG, EXS and SG: 147.5 +/- 28.1, 135.8 +/- 30.2 and 41.0 +/- 10.7 pg/ml, respectively (P = 0.0006, P = 0.0010 and P = 0.0003; analysis of variance). The mean concentration (+/- standard error) of total TGF-beta 2 in the aqueous humor of eyes with POAG was 1647.6 +/- 124.5 pg/ml, not significantly different from that in eyes with PACG, EXS and SG: 1482.9 +/- 148.2, 1442.7 +/- 187.8 and 1929.0 +/- 367.6 pg/ml, respectively. A multivariate analysis using logistic regression showed significant correlations between mature TGF-beta 2 concentration and history of cataract surgery (P = 0.0225) and the use of carbonic anhydrase inhibitors (P = 0.0143). CONCLUSIONS: Our results indicate that increased levels of TGF-beta 2 may play an important role in the pathogenesis of POAG.     

【In Press】 Safety threshold of intravitreal clonidine in rabbits eyes

AIM: To determine the safe dose of intravitreal clonidine (IVC), a potential drug for neuroprotection and angiogenesis inhibition, in rabbits. METHODS: 28 rabbits were divided into four groups. Three of these groups received IVC with concentrations of 15 (A), 25 (B), and 50 (C) µg/0.1 cc and the control group (D) received 0.1 cc balanced salt solution (BSS). To investigate IVC safety, electroretinography (ERG) was performed at baseline, then at 1, 4 and 8wk after injection. After last ERG, all rabbits were euthanized, their eyes were enucleated and subjected to routine histopathological evaluation, immunohistochemistry for glial fibrillary acidic protein (GFAP) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) test. RESULTS: Based on ERG, histopathology, GFAP and TUNEL assay findings, 15 µg IVC was determined as the safe dose in rabbit eyes. While, the results of routine histopathology and TUNEL assay were unremarkable in all groups, toxic effects attributed to 25 and 50 µg IVC were demonstrated by ERG and GFAP tests. CONCLUSION: 15 µg clonidine was determined as the safe dose for intravitreal injection in rabbits. Contribution of IVC in neuroprotection and inhibition of angiogenesis deserves more studies.     

Can we trust intraocular pressure measurements in eyes with intracameral air?

Purpose

To evaluate the effect of intracameral air on intraocular pressure (IOP) measurements using Goldmann applanation tonometry (GAT) and applanation resonance tonometry (ART) in an in-vitro porcine eye model.

Methods

IOP was measured on thirteen freshly enucleated eyes at three reference pressures: 20, 30, and 40 mmHg. Six measurements/method were performed in a standardized order with GAT and ART respectively. Air was injected intracamerally in the same manner as during Descemet’s stripping endothelial keratoplasty (DSEK) and Descemet’s membrane endothelial keratoplasty (DMEK), and the measurements were repeated.

Results

Measured IOP increased significantly for both tonometry methods after air injection: 0.7?±?2.1 mmHg for GAT and 10.6?±?4.9 mmHg for ART. This difference was significant at each reference pressure for ART but not for GAT.

Conclusions

Although slightly affected, this study suggests that we can trust GAT IOP-measurements in eyes with intracameral air, such as after DSEK/DMEK operations. Ultrasound-based methods such as ART should not be used.     

Does amblyopia therapy make sense in eyes with severe organic defects?

BACKGROUND: In eyes with severe organic defects the question arises if amblyopia therapy makes sense. PATIENTS AND METHODS: Three children are presented in whom despite severe organic eye diseases amblyopia therapy was tried. The first child had a unilateral large macular scar secondary to retinoblastoma treatment, the second a unilateral severe optic nerve atrophy secondary to an orbital hemangioma, and the third a unilateral large optic nerve coloboma. RESULTS: In the first case a reading visual acuity of 0.9 was achieved by occlusion therapy and in the second a reading visual acuity of 0.5. In the third case occlusion lead to alternation of the divergent strabismus (child too strongly retarded for reliable visual acuity measurements). CONCLUSIONS: During the sensitive phase, amblyopia therapy is also indicated in eyes with severe organic defects since good visual acuities can be achieved.     

Subclinically dry eyes in urban Delhi: an impact of air pollution?

PURPOSE: To study the effects of air pollution on the eyes of persons staying in the metropolis of New Delhi. MATERIALS AND METHODS: 400 healthy volunteers from within and outside the metropolis of Delhi were investigated for the presence of tear film abnormalities. All persons underwent slitlamp examination to rule out any ocular surface disorder. The tear break-up time (BUT) was assessed along with a Schirmer test and the tear lysozyme activity and the tear pH were determined. RESULTS: Of the 210 persons staying in the metropolis, 50 (24%) had an abnormal BUT, 14 (6.6%) had an abnormal Schirmer test, and the tear lysozyme activity was found to be low in 12 (5%). In contrast, of those 190 persons living outside the metropolis, only 10 (5.2%) had an abnormal BUT, 4 (2%) had an abnormal Schirmer test, and none had a low lysozyme activity (p < 0.05). None of the persons in either group had significant eye symptoms. CONCLUSIONS: Tear film abnormalities are present in a large number of people staying within the metropolis of New Delhi who have apparently normal eyes. Air pollution over a long period of time could possibly be associated with their causation.     

Twenty-four hours intraocular pressure in keratoconic eyes assessed by applanation tonometry and Tono-Pen AVIA

AIM:To assess intraocular pressure(IOP)during the daily curve of intraocular pressure(DCPo)in keratoconic eyes and compare Goldmann applanation tonometer(GAT),without and with astigmatism correction(n GAT and c GAT)and Tono-Pen AVIA(TPA)assessment methods.METHODS:Thirty-nine keratoconic eyes of 24 patients were assessed.DCPo was evaluated with five IOP measurements;four were performed with a GAT(n GAT and c GAT),and a Tono-Pen AVIA(TPA)at various times throughout the day.RESULTS:Mean IOP DCPo values(mm Hg)were:n GAT,9.9±2.6;c GAT,11.3±2.6;TPA 12.3±3.1.Mean IOP DCPo differences(mm Hg)and Spearman’s correlation coefficients were as follows:c GATc-n GAT,1.32±1.31,r_s=0.879(P<0.01);c GAT-TPA,-1.02±2.08,r_s=0.723(P<0.01);and n GAT-TPA,-2.35±2.23,r_s=0.730(P<0.01).Bland-Altman analysis for agreement between c GAT-TPA and n GAT-TPA mean IOP DCPo measurements revealed a mean difference of 1.02(95%CI,0.35-1.70)and 2.35(95%CI,1.62-3.07)mm Hg,respectively.Regression analysis yielded the following equation:TPA IOP=5.49+0.775×c GAT-0.015×ACD-0.299×corneal astig matism,which allowed us to infer TPA IOP values from other parameters.CONCLUSION:In keratoconic eyes,IOP peaks of DCPo measurements are identified at 6 a.m.,independent of the tonometer.The mean DCPo values are:TPA>c GAT>n GAT.IOP TPA measures are predictive of c GAT values,adjusted according to anterior chamber depth and corneal astigmatism.     

Biochemical studies on human corneal proteoglycans —a comparison of normal and keratoconic eyes

Human corneas from normal (healthy) donors and patients with keratoconus were either metabolically labelled under organ culture conditions or investigated without preincubation. The sulfated proteoglycans were isolated from a 4M guanidinium chloride/2% Triton X 100 extract. Two predominant proteoglycans were obtained from normal cornea after digestion of total sulfated proteoglycans with chondroitin ABC-lyase or endo--galactosidase. One had an overall mass of 150 kDa, two dermatan sulfate chains (M _r50 kDa) with an iduronic acid content of 24%–28% and, after chondroitin ABC-lyase digestion, a core protein of 48 kDa. The other proteoglycan had an overall mass of 110 kDa, one keratan sulfate chain of 60 kDa and, following endo--galactosidase (keratanase) digestion, a core protein of 46 kDa. Each proteoglycan population was further fractionated into two subpopulations by chromatography on concanavalin A-Sepharose. The dermatan sulfateand keratan sulfate-containing proteoglycans isolated from keratoconic and healthy cornea had comparableM _r values and core proteins with identical molecular weights, but the ratio of dermatan sulfate/keratan sulfate proteoglycan was increased in keratoconic cornea and the keratan sulfate chains of two keratan sulfate proteoglycans from keratoconic cornea were considerably shorter (M _r 44 and 33 kDa) than those from normal corneas.