Non-treated Eyes Research Articles

Retinal Laser Burn Disrupts Immune Privilege in the Eye

Immune privilege allows for the immune protection of the eye in the absence of inflammation. Very few events are capable of overcoming the immune-privileged mechanisms in the eye. In this study, we report that retinal laser burn (RLB) abrogates immune privilege in both the burned and nonburned eye. As early as 6 hours after RLB, and as late as 56 days after RLB, antigen inoculation into the anterior chamber of the burned eye failed to induce peripheral tolerance. After RLB, aqueous humor samples harvested from nontreated eyes but not from either the burned or the contralateral eye, down-regulated the expression of CD40 and up-regulated interleukin-10 mRNA in peritoneal exudate cells, and converted peritoneal exudate cells into tolerogenic antigen-presenting cells (APCs). Unlike F4/80(+) APCs from nontreated mice, F4/80(+) APCs from RLB mice were unable to transfer tolerance after anterior chamber inoculation of antigen into naïve mice. The increased use of lasers in both the industrial and medical fields raises the risk of RLB-associated loss of immune regulation and an increased risk of immune inflammation in the eye.

Tensioactive-mediated Transepithelial Corneal Cross-linking – First Laboratory Report

Purpose:The aim of this study was to investigate the possibility of delivering riboflavin into the corneal stroma for cross-linking with the aid of a tensioactive substance (benzalkonium chloride), without removing the epithelium, in order to make corneal cross-linking (CXL) a less invasive technique.Methods:Rabbit corneas were cross-linkedin vivowithout removal of the epithelium, using riboflavin solution 0.1% to which benzalkonium chloride solution was added. The corneas were then examined by light and electron microscopy for evidence of collagen cross-linking. Control non-treated eyes were compared with treated ones.Results:The treated corneas were stiff and yellow in colour, and on light microscope examination they showed straight compact collagen fibres in comparison with control corneas in approximately 50% of the corneal thickness. Electron microscopy revealed regular arrangement of fibres in the outer 200μm with reduced inter-fibre distances in the treated corneas, but with no noticeable differences between control and treated corneas in the inner 100μm.Conclusion:The addition of benzalkonium chloride to the riboflavin solution facilitated its entry to the corneal stroma through the epithelium, and CXL occurred without epithelium removal.

Effect of Bevacizumab on Human Corneal Endothelial Cells: A Six-month Follow-up Study

To assess in vivo corneal endothelial changes occurring over a six-month period after the intravitreal injection of bevacizumab (Avastin; Genentech Inc, San Francisco, California, USA) in patients with various macular diseases. Prospective case series. A total of 50 eyes from 50 consecutive patients received an intravitreal injection of 2.5 mg intravitreal bevacizumab. Specular microscopy, including central corneal thickness (CCT) and endothelial cell count, was performed on each patient for both eyes before injection and one day, seven days, three months, and six months after injection. The CCT at one and seven days was measured to evaluate the acute corneal endothelial damage; endothelial cell count at three and six months was used to estimate chronic corneal endothelial change. All patients completed six months of follow-up. There was no significant difference in corneal thickness change between treated and nontreated eyes before injection or one and seven days after injection (P = .53, .34, and .87, respectively). There was also no difference in the treated eyes before injection and one and seven days after injection (P = .94). Long-term evaluation revealed that there was no significant difference in the corneal endothelial cell density of treated and nontreated eyes before injection and at three and six months after injection (P = .76, .13, and .22, respectively). There was also no difference in the treated eyes before injection and at three and six months after injection (P = .73). The intravitreal injection of 2.5 mg bevacizumab seemed to have no harmful effects on the corneal endothelium.

Intersession Repeatability of Visual Acuity Scores in Age-Related Macular Degeneration

To describe the intersession repeatability of visual acuity measures obtained with Early Treatment of Diabetic Retinopathy Study (ETDRS) charts in patients with age-related macular degeneration. Visual acuity was measured in four sessions over 12 weeks using a standardized protocol with ETDRS charts in 107 nontreated eyes of 107 patients with age-related macular degeneration enrolled in an ongoing clinical trial. Data from 90 patients were included in the analysis. The 95% coefficient of repeatability (CR) was 12 ETDRS letters and ranged from 9 letters for 29 eyes with small to intermediate drusen only to 17 letters for 25 eyes with late AMD (macular scars or geographic atrophy). Ten (11%) eyes had a 5-letter reduction or more in visual acuity at the week 1 visit compared with baseline. Excluding seven eyes with visual acuity measurements potentially affected by measurement-related factors (a change in testing distance between visits) the revised CR was 10 letters for the cohort (n = 83) and 11 letters for the late-AMD subgroup (n = 18). Intersession ETDRS visual acuity measurements are subject to considerable variability in patients with AMD. The variability may be due to both measurement- and disease-related factors. The variable readings have implications for AMD clinical trial design and for the assessment and treatment of patients with neovascular AMD. Further work is needed to determine both the sources of variability in visual acuity measurements and the optimal change criterion for visual acuity measurements in this important group of patients.

Effects of Modifiers of Glycosaminoglycan Biosynthesis on Outflow Facility in Perfusion Culture

Glycosaminoglycans (GAGs) have been implicated in the regulation of outflow resistance of aqueous humor flow through the trabecular meshwork (TM). Their role was further investigated by assessment of the effects of chlorate, an inhibitor of sulfation, and beta-xyloside, which provides a competitive nucleation point for addition of disaccharide units, in anterior segment perfusion culture. Outflow facility was measured in perfused porcine and human anterior organ cultures treated with 20 or 50 mM sodium chlorate, or 1 mM beta-xyloside. Perturbation of extracellular matrix (ECM) components was assessed in paraffin-embedded sections by immunofluorescence and confocal microscopy. Parallel experiments were conducted on cultured TM cells. Outflow facility increased in porcine eyes with chlorate (3-fold) and beta-xyloside (3.5-fold) treatments. In human eyes, outflow increased approximately 1.5-fold and took longer (>48 hours) to occur. By confocal microscopy, immunostaining for chondroitin and heparan sulfates was observed on edges of human TM beams in nontreated eyes, with intense staining in the juxtacanalicular tissue (JCT) region. In treated eyes, staining of beam edges was severely reduced and was instead found in plaques. Chlorate treatment resulted in a striated pattern of GAG staining in the human JCT region. Fibronectin immunostaining was altered in beta-xyloside-treated eyes, whereas in cell culture, chlorate induced formation of thick fibronectin fibrils, to which tenascin C colocalized. Disrupting GAG chain biosynthesis increased outflow facility in perfusion culture and induced atypical ECM molecule interactions in cell culture. This study provides direct evidence of the critical role of GAG chains in regulating outflow resistance in human TM.

Non-invasive gene transfer by iontophoresis for therapy of an inherited retinal degeneration

Despite extensive research on many of the genes responsible for inherited retinal degenerations leading to blindness, no effective treatment is currently available for patients affected with these diseases. Among the therapeutic approaches tested on animal models of human retinal degeneration, gene therapy using different types of viral vectors as delivery agents has yielded promising results. We report here our results on a non-invasive, non-viral delivery approach using transscleral iontophoresis for transfer of plasmid DNA into mouse retina. Proof of principle experiments were carried out using plasmid containing GFP cDNA to demonstrate expression of the transferred gene in the retina after single applications of iontophoresis. Various parameters for multiple applications of iontophoresis were optimized to sustain GFP gene expression in mouse photoreceptors. Subsequently, repeated iontophoresis of plasmid containing normal cGMP-phosphodiesterase β-subunit (β-PDE) cDNA was performed in the rd1 mouse, an animal model of autosomal recessive retinitis pigmentosa caused by a mutant β-PDE gene. In normal mice, transscleral iontophoresis of the GFP plasmid provided a significant increase in fluorescence of the retina in the treated versus non-treated eyes. In rd1 mice, repeated iontophoresis of β-PDE cDNA plasmid partially rescued photoreceptors morphologically, as observed by microscopy, and functionally, as recorded on ERG measurements, without adverse effects. Therefore, transscleral iontophoresis of plasmid DNA containing therapeutic genes may be an efficient, safe and non-invasive method for the treatment of retinal degenerations.

The effect of a single dose of topical 0.005% latanoprost and 2% dorzolamide/0.5% timolol combination on the blood‐aqueous barrier in dogs: a pilot study

To determine the effects of 0.005% latanoprost and 2% dorzolamide/0.5% timolol on the blood-aqueous barrier (BAB) in normal dogs. Eight mixed-breed and pure-breed dogs. Baseline anterior chamber fluorophotometry was performed on eight normal dogs. Sodium fluorescein was injected and the dogs were scanned 60-90 min post-injection. Seventy-two hours following the baseline scan, one eye received one drop of latanoprost. Fluorophotometry was repeated 4 h after drug administration. Following a washout period, the identical procedure was performed 4 h after the administration of dorzolamide/timolol. The degree of BAB breakdown was determined by comparing the concentrations of fluorescein within the anterior chamber before and after drug administration. BAB breakdown was expressed as a percentage increase in the post-treatment fluorescein concentration over the baseline concentration: %INC [Fl] = {([Fl](post)-[Fl](baseline))/[Fl](baseline)} x 100. The percentage increase in fluorescein concentration in the treated eye was compared to that in the nontreated eye using a paired t-test with significance set at P < or = 0.05. Following administration of latanoprost, the fluorescein in the treated eyes increased 49% (+/- 58%) from baseline compared to 10% (+/- 31%) in the untreated eyes (P = 0.016). Following administration of dorzolamide/timolol, the fluorescein concentration increased 38% (+/- 54%) compared to baseline vs. 24% (+/- 38%) in the untreated eyes (P = 0.22). The results of this study show that topical latanoprost may cause BAB disruption in normal dogs while topical dorzolamide/timolol may have no effect on the BAB in normal dogs.

Discrepancy of the Intraocular Pressure Response Between Fellow Eyes in One-eye Trials Versus Bilateral Treatment: Verification With Normal Subjects

To compare the correlation of the fellow-eye's intraocular pressure (IOP) response in one-eye trials performed separately for each eye with that of bilateral treatment in normal subjects. A one-eye trial with topical latanoprost applied once daily for 7 days was carried out in the right eye and then in the left eye of 41 normal subjects. Bilateral treatment was performed in a different set of 41 normal subjects. IOPs were measured at 3 time points on day 0 and on day 7. Latanoprost significantly reduced IOP of treated eyes in one-eye trials (2.8+/-1.6 and 2.7+/-1.6 mm Hg in the first and second trial, respectively) and in bilateral treatments (2.8+/-1.3 and 2.6+/-1.4 mm Hg in the right and left eye, respectively). Correlation of mean diurnal IOP reduction between 2 one-eye trials was poor (r2=0.102), even after subtracting the nontreated eye IOP fluctuations from the treated eye IOPs (r2=0.097), but that between fellow eyes in bilateral treatment was excellent (r=0.849). Correlation of baseline IOP at each time point between fellow eyes in one-eye trials and bilateral treatment (r2=0.729 to 0.949) was better than that in the same eye between 2 one-eye trials (r2=0.319 to 0.631). Fellow eyes in normal subjects showed a symmetrical IOP response to short-term bilateral treatment with latanoprost, although they did not respond symmetrically to one-eye trials performed separately for each eye. Poor correlation of IOP changes between 2 one-eye trials may be caused by different IOP responsiveness to latanoprost at each trial, rather than asymmetrical IOP fluctuations.

Selective inner retinal dysfunction precedes ganglion cell loss in a mouse glaucoma model

Background/aims:To correlate ganglion cell function with defined parameters of the elevated intraocular pressure profile (IOP) in a mouse glaucoma model and to determine the temporal relationship of these functional changes...

Multifocal electroretinographical changes in monkeys with experimental ocular hypertension: a longitudinal study

To study the time course of changes in the multifocal electroretinograms (mfERG) in monkeys with experimental ocular hypertension (OHT). The mfERGs were recorded in 12 eyes out of 6 monkeys. Two baseline measurements were used to quantify the reproducibility, the inter-ocular and the inter-individual variability of the ERG signals. Thereafter, the trabeculum of one eye of each animal was laser-coagulated in one to three sessions to induce OHT. ERG measurements were repeated regularly in a period of 18 months and the changes in ERG waveforms were quantified. All animals displayed OHT (between 20 and 50 mmHg) in the laser-coagulated eyes. An ERG change was defined as the sum of differences during the first 90 ms between the laser-coagulated eye and the same eye before laser coagulation and between the laser-coagulated eye and the non-treated fellow eye. Three animals displayed significant changes for nearly all retinal areas and all stimulus conditions. The three remaining animals displayed significant changes only in one comparison, indicating very mild changes. The data indicate that a high stimulus contrast is more sensitive to detect changes, probably because of a better signal-to-noise ratio. Moreover, the comparisons with the fellow eye are more sensitive to detect changes than comparisons with the measurements before laser-coagulation. OHT does not always lead to ERG changes. Comparisons with fellow eyes using high contrast stimuli are more sensitive to detect changes related to OHT.

Effect of Brimonidine Tartrate 0.15% on Scotopic Pupil: Controlled Trial

The aim of this study was to evaluate the duration of the effect of one single dose of brimonidine tartrate 0.15% on pupil diameter, under scotopic conditions, when applied topically in 1 eye of normal subjects. The eyes of 19 normal volunteers were randomized so that 1 eye had 1 drop of brimonidine tartrate 0.15% and the other received no medication. Pupil diameter was measured using an infrared pupillometer. The first measure was obtained before the instillation of brimonidine. After that, four measures, with 2-h intervals, were performed. From 19 participants, 14 were women and 5 were men, with a mean age of 25.05 years (standard deviation, +/- 6.98). Before brimonidine instillation, mean pupil diameter in the control eyes was 5.11 mm, and in the brimonidine eyes it was 5.15 mm. After 8 h, the mean pupil size was 4.01 mm in the treated eyes, and 4.56 mm in the untreated eyes. There was a tendency of miotic effect to be more important on the treated eye, as compared to the control eye in all intervals, but this did not reach statistical significance (P = 0.375). When comparing both eyes, independently of the periods, the treated eye had a smaller diameter than the untreated eye (P = 0.038). The miotic effect was observed for at least 8 h after instillation. Miotic response of brimonidine tartrate 0.15% lasted for at least 8 h and has a significant effect on the nontreated eye.

Efeitos maleato de timolol 0.5% do cloridrato de dorzolamida 2%, e da associação de ambas na pressão intra-ocular

Avaliaram-se efeitos da dorzolamida do timolol e da combinação de ambos sobre pressão intra-ocular (PIO) de cães normais, além de alterações no olho contralateral, não-tratado. Foram utilizados 60 cães sadios, distribuídos em três grupos (G) de 20 animais. No primeiro grupo (GT), foi avaliada a ação do maleato de timolol 0,5% na PIO; no segundo (GD), a ação do cloridrato de dorzolamida 2%; e, no terceiro (GTD), o efeito da associação fixa timolol/dorzolamida. A PIO foi aferida utilizando-se tonômetro de aplanação (Tonopen®), uma hora antes e uma, duas, quatro, seis e oito horas após a instilação do colírio em análise no olho esquerdo. O efeito da associação timolol/dorzolamida foi mais intenso (27%) que os efeitos do timolol (21,9%) e da dorzolamida (22,4%) na redução da PIO. No olho contralateral, verificou-se redução de 7% no GT, 13,8% no GD e 13,6% no GTD, após quatro e duas horas da administração.

Association between Genetic Polymorphisms of the Prostaglandin F 2α Receptor Gene and Response to Latanoprost

To evaluate the relationship between polymorphisms of the prostaglandin F(2alpha) receptor (FP receptor) gene and the effectiveness of topical latanoprost treatment in normal volunteers. Prospective nonrandomized trial. One hundred normal volunteers were recruited into the study. Baseline intraocular pressures (IOPs) of both eyes of 100 normal subjects were measured at 3 time points. Latanoprost (0.005%) was applied to one eye once daily for 7 days. Diurnal IOP was measured again on day 7. Response to latanoprost was evaluated by percent IOP reduction in the treated eye minus IOP fluctuations of the nontreated eye. We classified subjects by the mean diurnal percent IOP reduction (%DeltaIOP) into 3 groups: low responders (%DeltaIOP<10), medium responders (10< or =%DeltaIOP<25), and high responders (%DeltaIOP> or =25). Single-nucleotide polymorphisms (SNPs) in the FP receptor gene were searched, and the genotype was determined mainly by direct DNA sequencing. A promoter assay with a reporter luciferase gene was also performed. Mean diurnal percent IOP reduction and genotyping of SNPs in the FP receptor gene. Ten SNPs were identified in this study. One, rs3753380, was located in the promoter region of the FP receptor gene and was significantly correlated with %DeltaIOP (CC, 20.3%+/-1.5% [mean +/- standard error]; CT + TT, 15.6%+/-1.2%; P = 0.0316). Mean diurnal percent IOP reduction was not associated with the other SNPs. When the category classified by %DeltaIOP was analyzed, not only rs3753380 but also rs3766355, an SNP in intron 1, were associated with the degree of response to latanoprost. The promoter assay revealed that the C allele of rs3766355 and T allele of rs3753380 were found in constructs with lower transcriptional activity of the FP receptor gene. rs3753380 and rs3766355, SNPs in the promoter and intron 1 regions of the FP receptor gene, correlate with a response to short-term latanoprost treatment in normal volunteers. The genotype of these SNPs may be an important determinant of variability in response to latanoprost.

Intravitreal triamcinolone acetonide for treatment of intraocular oedematous and neovascular diseases

Intravitreal triamcinolone acetonide (IVTA) has increasingly been applied as treatment for various intraocular neovascular and oedematous diseases. Comparing the various diseases with respect to effect and side-effects of the treatment, the best response in terms of gain in visual acuity (VA) has been achieved for intraretinal oedematous diseases such as diffuse diabetic macular oedema, branch retinal vein occlusion, central retinal vein occlusion and pseudophakic cystoid macular oedema. In eyes with various types of non-infectious uveitis, including acute or chronic sympathetic ophthalmia and Adamantiadis-Behcet's disease, VA increased and the degree of intraocular inflammation decreased. Some studies have suggested that intravitreal triamcinolone may be useful as angiostatic therapy in eyes with iris neovascularization and proliferative ischaemic retinopathies. Intravitreal triamcinolone may possibly be helpful as adjunct therapy for exudative age-related macular degeneration (AMD), particularly in combination with photodynamic therapy. In eyes with chronic, therapy-resistant ocular hypotony, intravitreal triamcinolone can induce an increase in intraocular pressure (IOP) and may stabilize the eye. The complications of intravitreal triamcinolone therapy include: secondary ocular hypertension in about 40% of the eyes injected; medically uncontrollable high IOP leading to antiglaucomatous surgery in about 1-2% of the eyes; posterior subcapsular cataract and nuclear cataract leading to cataract surgery in about 15-20% of elderly patients within 1 year of injection; postoperative infectious endophthalmitis occurring at a rate of about one per 1000; non-infectious endophthalmitis, perhaps due to a reaction to the solvent agent, and pseudo-endophthalmitis with triamcinolone acetonide crystals appearing in the anterior chamber. Intravitreal triamcinolone injection can be combined with other intraocular surgeries, including cataract surgery, particularly in eyes with iris neovascularization. Cataract surgery performed some months after the injection does not show a markedly elevated complication rate. The injection may be repeated if the resultant benefits decrease after the initial IVTA injection. In non-vitrectomized eyes, the duration of the effect and side-effects of a single intravitreal injection of triamcinolone is about 6-9 months for a dosage of about 20 mg, and about 2-4 months for a dosage of 4 mg. So far, it has remained unclear whether the solvent agent should be removed, and if so, how.

External-beam radiation therapy for age-related macular degeneration: two years’ follow-up results at a total dose of 20 Gy in 10 fractions

PURPOSE The efficacy of external-beam radiation therapy (RT) was evaluated in the treatment of eyes with subfoveal or juxtafoveal choroidal neovascularization in age-related macular degeneration (ARMD). MATERIALS AND METHODS Twenty-one eyes of 18 patients with occult or mixed-type ARMD received a total dose of 20 Gy of 6 MV X-rays in 10 fractions. The follow-up time was 24 months. Fifteen non-treated eyes of 13 patients who had been followed served as a control. RESULTS In the RT group, visual acuity was improved in three eyes, maintained in 14 eyes, and worsened in four eyes. In the control group, it was not improved in any eyes, was maintained in six eyes, and worsened in nine eyes. The improved or maintained rate in visual acuity was 81% in the RT group and 40% in the control group (p=0.0342). In the RT group, fundoscopic and angiographic findings were improved in five eyes, unchanged in seven eyes, and worsened in nine eyes, while they were not improved in any eyes, unchanged in two eyes, and worsened in 13 eyes in the control group(p=0.0342). CONCLUSION RT at a total dose of 20 Gy in 10 fractions is effective for ARMD for at least two years. RT may be effective treatment for occult or mixed-type ARMD compared with the classic type.

Ocular inflammation alters swelling and membrane characteristics of rat Müller glial cells

Ocular inflammation is a common cause of retinal edema that may involve swelling of Müller glial cells. In order to investigate whether endotoxin-induced ocular inflammation in rats alters the swelling and membrane characteristics of Müller cells, lipopolysaccharide (LPS; 0.5%) was intravitreally injected. At 3 and 7 days after treatment, hypotonic challenge induced swelling of Müller cell somata that was not observed in non-treated control eyes. Müller cells of LPS-treated eyes displayed a downregulation of inward K + currents and upregulation of A-type K + currents that was associated with a decreased expression of Kir4.1 protein in retinal slices. The data suggest that ocular inflammation induces alterations of both the swelling characteristics and the K + channel expression of Müller cells.

Retinal vein cannulation with prolonged infusion of tissue plasminogen activator (t-PA) for the treatment of experimental retinal vein occlusion in dogs

To evaluate the feasibility, safety, and efficacy of local thrombolytic agents directly injected into occluded retinal veins in an experimental animal model. Experimental animal study. This experimental study was performed in two phases. In phase 1, 15 enucleated porcine eyes and 8 in vivo canine eyes were used for the development of the instrumentation and surgical technique required for retinal vein cannulation with prolonged intravascular infusion. In phase 2 of this study, experimental branch retinal vein occlusion was photo-chemically created using an intravenous injection of rose bengal followed by diode laser photocoagulation in eight eyes of eight dogs. Four eyes were treated by retinal vein cannulation and an injection of tissue plasminogen activator (t-PA) using a specifically designed microcatheter, while the remaining four eyes were untreated (control group). The total amount of t-PA injected intravenously ranged from 400 to 1000 mug, infused over a period ranging from 25 to 45 minutes with a mean pressure of 40 psi, resulting in a mean injection flow rate of 0.05 ml/min. The dogs underwent clinical examination, fluorescein angiography, and histologic examination. Main outcome measures were: Achievement of prolonged intravascular infusion of t-PA, changes in fundus appearance, fluorescein angiography, and histology. A microcatheter instrument and a surgical technique for retinal vein cannulation with prolonged intravascular infusion were developed. Cannulation and t-PA infusion for a period of at least 30 minutes was achieved in all four treated eyes with experimental branch retinal vein occlusion. No complications were recorded in all treated eyes. One week and 1 month postoperatively, treated eyes exhibited marked decreases in retinal hemorrhages, retinal vein dilation, and tortuosity, whereas nontreated eyes exhibited persistence of these findings. Fluorescein angiography demonstrated improved circulatory flow in treated relative to nontreated eyes. Histologic analysis confirmed the presence of thrombi in nontreated eyes only. Retinal vein cannulation with prolonged intravascular injection of t-PA is feasible and safe, and this may offer a new treatment option for retinal vein occlusion.

Betaxolol attenuates retinal ischemia/reperfusion damage in the rat.

This study was performed to elucidate the protection afforded by post-treatment with Betoptic (0.25% betaxolol) against neuronal cell damage after ischemia/reperfusion insult in rats. Betaxolol was applied topically after the start of reperfusion and its effect was evaluated by morphometry and choline acetyltransferase immunoreactivity of retinas at 7 days after reperfusion. In non-treated eyes, the thickness of the inner plexiform layer decreased markedly after a reperfusion period of both 3 and 7 days. However, when eyes were treated with betaxolol after ischemia/reperfusion injury, both the reduction of the inner plexiform layer thickness and the retinal choline acetyltransferase immunoreactivity were significantly attenuated. These findings suggest that betaxolol is an efficient neuroprotective agent and prevents the retinal cell damage induced by ischemic injury in rats.

Diffuse lamelläre Keratitis

The aim of this experimental ani-mal study was to induce diffuse lamellar keratitis (DLK), and investigate a prophylactic treatment with corticosteroids. A corneal flap was cut in 40 eyes from 20 Dutch-belted rabbits and the interface inoculated with either Pseudomonas aeruginosa lipopolysaccharide (LPS) endotoxin ( n=21) or Palmolive Ultra soap ( n=19). Half of the eyes were treated with topical corticosteroids and the other half remained untreated. Slitlamp examinations were performed 1, 3, 5 and 7 days postoperatively and DLK was graded from I-IV. At the end of the study 33 eyes were available for evaluation and 94% of the non-treated eyes developed DLK. Out of those eyes treated with steroids 19% developed DLK during the 1 week follow-up period. This was statistically significantly lower ( P=0.018) when compared to the untreated group. Pseudomonas aeruginosa LPS endotoxin as well as Palmolive((R)) Ultra caused a very high rate of DLK in rabbit eyes. The postoperative prophylactic treatment with corticosteroids showed a statistically significant lower DLK rate in this rabbit eye model.

Temporal Relationship of Choroidal Blood Flow and Thickness Changes during Recovery from Form Deprivation Myopia in Chicks

When form deprived, young chicks rapidly develop axial myopia, from which they recover if the treatment is ceased at a sufficiently early age. The increased axial growth of the eye is accompanied by choroidal thinning and decreased choroidal blood flow (ChBF). In contrast, during the early part of the recovery process, the choroid thickens, shifting the retina towards the new plane of focus. Little information is available about ChBF during recovery from myopia. Because of the possibility that choroidal thickening during recovery from myopia might be driven by an increase in ChBF, the temporal relationship of ChBF and choroidal thickness changes was examined during such recovery.White Leghorn chicks were form deprived from 3 days of age for 2–3 weeks using detachable plastic diffusers. Axial ocular dimensions, including choroidal thickness, were then measured by high frequency A-scan ultrasonography at various times after the diffusers were removed up to 240hr. ChBF was measured transclerally immediately following the A-scan ultrasonography, using laser Doppler flowmetry.In the chicks measured immediately after diffuser removal, the vitreous chamber was 29.9% longer, the choroid was 6.4% thinner and ChBF was 13.7% less in the treated than in the non-treated control eyes. These changes are characteristic of myopic chick eyes and are reversible in young eyes. Thus, in chicks examined 7hr after diffuser removal, the ChBF in recovering eyes was now greater than that in control eyes. This ChBF increase peaked about 19hr after the diffusers were removed. The mean increase in ChBF in treated eyes for the 7–30hr monitoring period was 187%, relative to control eyes. ChBF in the treated eyes gradually returned to the control level after this time. By contrast to the early, transient increase in ChBF, significant choroidal thickening was not observed in treated eyes until 30hr after diffuser removal, and continued to increase relative to control eyes over the remainder of the monitoring period, reaching a final mean value of 182%.This study demonstrates, in chick eyes recovering from form deprivation myopia, large increases in ChBF that preceded increases in choroidal thickness and were also more transient than the latter. These results raise the possibility that the increase in ChBF may trigger or even drive the subsequent onset of choroidal expansion, perhaps by facilitating the filling of the choroidal lymphatic lacunae that are well developed in the avian eye.