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Among the environmental factors contributing to myopia, the role of correlated color temperature (CCT) of ambient light emerges as a key element warranting in-depth investigation. The choroid, a highly vascularized and dynamic structure, often undergoes thinning during the progression of myopia, though the precise mechanism remains elusive. The retinal pigment epithelium (RPE), the outermost layer of the retina, plays a pivotal role in regulating the transport of ion and fluid between the subretinal space and the choroid. A hypothesis suggests that variations in choroidal thickness (ChT) may be modulated by transepithelial fluid movement across the RPE. Our experimental results demonstrate that high CCT illumination significantly compromised the integrity of tight junctions in the RPE and disrupted chloride ion transport. This functional impairment of the RPE may lead to a reduction in fluid transfer across the RPE, consequently resulting in choroidal thinning and potentially accelerating axial elongation. Our findings provide support for the crucial role of the RPE in regulating ChT. Furthermore, we emphasize the potential hazards posed by high CCT artificial illumination on the RPE, the choroid, and refractive development, underscoring the importance of developing eye-friendly artificial light sources to aid in the prevention and control of myopia., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Purpose: To determine whether light chromaticity without defocus induced by longitudinal chromatic aberration (LCA) is sufficient to regulate eye growth., Methods: An interferometric setup based on a spatial light modulator was used to illuminate the dominant eyes of 23 participants for 30 minutes with three aberration-free stimulation conditions: (1) short wavelength (450 nm), (2) long wavelength (638 nm), and (3) broadband light (450-700 nm), covering a retinal area of 12°. The non-dominant eye was occluded and remained as the control eye. Axial length and choroidal thickness were measured before and after the illumination period., Results: Axial length increased significantly from baseline for short-wavelength (P < 0.01, 7.4 ± 2.2 µm) and long-wavelength (P = 0.01, 4.8 ± 1.7 µm) light. The broadband condition also showed an increase in axial length with no significance (P = 0.08, 5.1 ± 3.5 µm). The choroidal thickness significantly decreased in the case of long-wavelength light (P < 0.01, -5.7 ± 2.2 µm), but there was no significant change after short-wavelength and broadband illumination. The axial length and choroidal thickness did not differ significantly between the test and control eyes or between the illumination conditions (all P > 0.05). Also, the illuminated versus non-illuminated choroidal zone did not show a significant difference (all P > 0.05)., Conclusions: All stimulation conditions with short- and long-wavelength light and broadband light led to axial elongation and choroidal thinning. Therefore, light chromaticity without defocus induced by LCA is suggested to be insufficient to regulate eye growth., Translational Relevance: This study helps in understanding if light chromaticity alone is a sufficient regulator of eye growth.

Purpose: Given the potential role of light and its wavelength on ocular growth, we investigated the effect of short-term exposure to the red, green, and blue light on ocular biometry in the presence and absence of lens-induced defocus in humans., Methods: Twenty-five young adults were exposed to blue (460 nm), green (521 nm), red (623 nm), and white light conditions for 1-hour each on 4 separate experimental sessions conducted on 4 different days. In each light condition, hyperopic defocus (3D) was induced to the right eye with the fellow eye experiencing no defocus. Axial length and choroidal thickness were measured before and immediately after the light exposure with a non-contact biometer., Results: Axial length increased from baseline after red light (mean difference ± standard error in the defocussed eye and non-defocussed eye = 11.2 ± 2 µm and 6.4 ± 2.3 µm, P < 0.001 and P < 0.01, respectively) and green light exposure (9.2 ± 3 µm and 7.0 ± 2.5 µm, P < 0.001 and P < 0.001) with a significant decrease in choroidal thickness (P < 0.05, both red and green light) after 1-hour of exposure. Blue light exposure resulted in a reduction in axial length in both the eyes (-8.0 ± 3 µm, P < 0.001 in the defocussed eye and -6.0 ± 3 µm, P = 0.11 in the non-defocused eye) with no significant changes in the choroidal thickness., Conclusions: Exposure to red and green light resulted in axial elongation, and blue light resulted in inhibition of axial elongation in human eyes. Impact of such specific wavelength exposure on children and its application in myopia control need to be explored.

Geographic atrophy (GA) is an advanced form of age-related macular degeneration (AMD) characterized by atrophy of the retinal pigment epithelium (RPE), loss of photoreceptors, and disruption of choriocapillaris. Excessive light exposure is toxic to the retina and is a known risk factor for AMD. We first investigated the effects of blue light-induced phototoxicity on RPE and photoreceptors in nonhuman primates (NHPs, a model of progressive retinal degeneration) and then evaluated the potential cyto- and neuroprotective effects of the brimonidine drug delivery system (Brimo DDS). In the first set of experiments related to model development, parafoveal lesions of varying severity were induced using blue light irradiation of the retina of cynomolgus monkeys to evaluate the level of phototoxicity in the RPE and photoreceptors. RPE damage was assessed using fundus autofluorescence imaging to quantify areas of hypofluorescence, while thinning of the outer nuclear layer (ONL, photoreceptor nuclei) was quantified using optical coherence tomography (OCT). Photoreceptor function was assessed using multifocal electroretinography (mfERG). RPE damage progressively increased across all lesion severities from 2 to 12 weeks, as did the extent of ONL thinning. Lesions of high severity continued to show reduction in mfERG amplitude, reaching a statistically significant maximum reduction at 12 weeks. Collectively, the first set of experiments showed that blue light irradiation of the NHP eye resulted in progressive retinal degeneration identified by damage to RPE, ONL thinning, and disrupted photoreceptor function - hallmarks of GA in humans. We then used the model to evaluate the cyto- and neuroprotective effects of Brimo DDS, administered as a therapeutic after allowing the lesions to develop for 5 weeks. Placebo DDS or Brimo DDS were administered intravitreally and a set of untreated animals were used as an additional control. In the placebo DDS group, hypofluorescence area continued to increase from baseline, indicating progressive RPE damage, while progression was significantly slowed in eyes receiving Brimo DDS. Likewise, ONL thinning continued to progress over time in eyes that received the placebo DDS, but was reduced in Brimo DDS-treated eyes. Pharmacologically relevant brimonidine concentrations were sustained in the retina for up to 26 weeks following Brimo DDS administration. In summary, Brimo DDS demonstrated cyto- and neuroprotective effects in a novel NHP GA model of progressive retinal degeneration., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Uncontrolled diabetes has been associated with progression of diabetic retinopathy (DR) in several studies. Therefore, we aimed to investigate systemic and ophthalmic factors related to worsening of DR even after completion of panretinal photocoagulation (PRP). We retrospectively reviewed DR patients who had completed PRP in at least one eye with a 3-year follow-up. A total of 243 eyes of 243 subjects (mean age 52.6 ± 11.6 years) were enrolled. Among them, 52 patients (21.4%) showed progression of DR after PRP (progression group), and the other 191 (78.6%) patients had stable DR (non-progression group). The progression group had higher proportion of proliferative DR (P = 0.019); lower baseline visual acuity (P < 0.001); and higher platelet count (P = 0.048), hemoglobin (P = 0.044), and hematocrit, (P = 0.042) than the non-progression group. In the multivariate logistic regression analysis for progression of DR, baseline visual acuity (HR: 0.053, P < 0.001) and platelet count (HR: 1.215, P = 0.031) were identified as risk factors for progression. Consequently, we propose that patients with low visual acuity or high platelet count are more likely to have progressive DR despite PRP and require careful observation. Also, the evaluation of hemorheological factors including platelet counts before PRP can be considered useful in predicting the prognosis of DR.

Purpose: To determine the effects of narrowband light exposure on choroidal thickness and the pupil response in humans., Methods: Twenty subjects, ages 21 to 43 years, underwent 1 hour of exposure to broadband, short wavelength "blue," or long wavelength "red" light, or darkness. Choroidal thickness, imaged with spectral domain optical coherence tomography, axial length, determined from biometry, and rod/cone- and intrinsically photosensitive retinal ganglion cell-driven pupil responses were measured before and after exposure. Pupil stimuli were six 1 second alternating red (651 nm) and blue (456 nm) stimuli, 60 seconds apart. Pupil metrics included maximum constriction and the 6 second post-illumination pupil response (PIPR)., Results: Compared with before exposure, the choroid significantly thinned after broadband light, red light, and dark exposure (all P < 0.05), but not after blue light exposure (P = 0.39). The maximum constriction to 1 second red stimuli significantly decreased after all light exposures (all P < 0.001), but increased after dark exposure (P = 0.02), compared with before exposure. Maximum constriction and 6-second PIPR to 1 second blue stimuli significantly decreased after all light exposures compared with before exposure (all P < 0.005), with no change after dark exposure (P > 0.05). There were no differences in axial length change or 6-second PIPR to red stimuli between exposures., Conclusions: Narrowband blue and red light exposure induced differential changes in choroidal thickness. Maximum constriction, a function of rod/cone activity, and the intrinsically photosensitive retinal ganglion cell-mediated PIPR were attenuated after all light exposures. Findings demonstrate differing effects of short-term narrowband light and dark exposure on the choroid, rod/cone activity, and intrinsically photosensitive retinal ganglion cells.

Purpose: For transscleral application of optical radiation or light to the eye, it is important to know the transmission and absorbance of the tissue layers of the eyewall. The impact of photochemical energy to the retina located directly at the point of contact with the radiation emitter must be considered as well as the absorbance in choroid and retina. Therefore, the direct transmission of ex vivo porcine eyewalls and vitreous body were measured in this study., Methods: At ex vivo porcine eyes (N=221) pressure dependent transmission measurements were performed with a pressure inducing setup. Pressure and wavelength dependent direct transmission of eyewall and vitreous body of porcine eyes were described for different applied pressures (23mmHg, 78mmHg and 132mmHg). The transmissions were investigated within the spectral range of 350-1050nm. In addition to the complete eyewall transmission measurements, the transmission of sclera, vitreous body and water was measured individually and the transmission of retina and choroid was calculated., Results: With increasing wavelength and pressure, a significant transmission increase of the eyewall could be achieved (p<0.05). At 400nm and 132mmHg the transmission raised to 0.10%. At 1050nm it increased up to a value of 12.22%. In the visible spectrum, the direct transmission was always below 3.17%. The differences in eyewall transmission of eyes with different iris colors were significant at low pressure. With increasing pressure, the effect strength decreased and the differences lost their significance., Conclusions: The pressure and wavelength dependent direct transmission of the eyewall and the vitreous body significantly increased with increasing pressure. This results are benefical for technical and clinical safety, research and development of illumination devices. It is necessary to know the intraocular brightness in the eye during diaphanoscopy, photocoagulation application to determine hazards., (Copyright © 2020. Published by Elsevier GmbH.)

Purpose: To evaluate the efficacy of photodynamic therapy using a double dose of verteporfin for patients with circumscribed choroidal hemangioma., Methods: This retrospective comparative case series evaluated data from 10 patients who were treated using double dose photodynamic therapy (12 mg/m) and seven patients who were treated using the standard dose (6 mg/m). A laser was applied with a radiant exposure of 50 J/cm. The ophthalmologic examinations were performed at baseline and 1 year after the treatment and included best-corrected visual acuity, slit-lamp biomicroscopy, fundus examination, spectral domain optical coherence tomography, and B-scan ultrasonography., Results: The mean age in the double dose group was 51.60 years, compared with 50.57 years in the standard-dose group. The only significant difference between the two groups' baseline characteristics was observed in their initial tumor heights. Foveal center thickness, subretinal fluid, and subfoveal choroidal thickness decreased significantly at 1 year after treatment in both groups. Tumor height and the greatest linear dimension of the tumor's base only decreased significantly in the double dose group (P = 0.031). Both groups did not experience significant visual improvements., Conclusion: Double dose photodynamic therapy was effective and safe for treating circumscribed choroidal hemangioma and provided better tumor regression with similar resorption of subretinal fluid, compared with standard-dose photodynamic therapy.

Mouse laser-induced choroidal neovascularization (mouse LCNV) recapitulates the "wet" form of human age-related macular degeneration (AMD). Vascular cell adhesion molecule-1 (VCAM-1) is a known inflammatory biomarker, and it increases in the choroidal neovascular tissues characteristic of this experimental model. We have designed and constructed gold nanoparticles (AuNPs) functionalized with hairpin-DNA that incorporates an antisense sequence complementary to VCAM-1 mRNA (AS-VCAM-1 hAuNPs) and tested them as optical imaging probes. The 3' end of the hairpin is coupled to a near-infrared fluorophore that is quenched by the AuNP surface via Förster resonance energy transfer (FRET). Hybridization of the antisense sequence to VCAM-1 mRNA displaces the fluorophore away from the AuNP surface, inducing fluorescent activity. In vitro testing showed that hAuNPs hybridize to an exogenous complementary oligonucleotide within a pH range of 4.5-7.4, and that they are stable at reduced pH. LCNV mice received tail-vein injections of AS-VCAM-1 hAuNPs. Hyperspectral imaging revealed the delivery of AS-VCAM-1 hAuNPs to excised choroidal tissues. Fluorescent images of CNV lesions were obtained, presumably in response to the hybridization of AS-hAuNPs to LCNV-induced VCAM-1 mRNA. This is the first demonstration of systemic delivery of hAuNPs to ocular tissues to facilitate mRNA imaging of any target.

Pathologic microvasculature plays a crucial role in innumerable diseases causing death and major organ impairment. A major clinical challenge is the development of selective therapies to remove these diseased microvessels without damaging surrounding tissue. This report describes our development of novel photo-mediated ultrasound therapy (PUT) technology for precisely removing choroidal blood vessels in the eye. PUT selectively removes microvessels by concurrently applying nanosecond laser pulses with ultrasound bursts. In PUT experiments on rabbit eyes in vivo, we applied 55-75 mJ/cm 2 of light fluence at the retinochoroidal surface at 532-nm and 0.5 MPa of ultrasound pressure at 0.5 MHz. PUT resulted in significantly reduced blood perfusion in the choroidal layer which persisted to four weeks without causing collateral tissue damage, demonstrating that PUT is capable of removing choroidal microvasculature safely and effectively. With its unique advantages, PUT holds potential for the clinical management of eye diseases associated with microvessels and neovascularization.

Background and Objective: Stereotactic radiotherapy (SRT) is a new adjuvant treatment modality that has been shown to reduce the need for repetitive intravitreal injections (IVIs) in patients with neovascular age-related macular degeneration (nAMD). The authors aimed to determine baseline predictors of clinical response to SRT., Patients and Methods: This was a retrospective, observational case series of patients with nAMD who underwent SRT and subsequently had at least 12 months of complete follow-up. After SRT and one mandatory IVI, patients were examined every 4 weeks and received further treatment on a pro re nata basis. Examination included enhanced depth imaging spectral-domain optical coherence tomography (SD-OCT) to measure subfoveal choroidal thickness (SFCT) and central macular thickness (CMT). Patients' data were retrieved from medical records and included demographics, disease duration, lesion size, best-corrected visual acuity (BCVA), previous number of IVIs, and type of drug applied., Results: A total of 35 eyes of 35 patients (76.23 years ± 7.05 years) were included, and 21 eyes (60%) responded well to SRT. The annual injection rate decreased from 6.86 before SRT to 3.46 afterward, whereas BCVA improved from 0.49 logMAR at baseline to 0.37 logMAR at final follow-up. From a morphologic point of view, CMT and SFCT decreased by 71 μm and 37 μm, respectively, at 12-month follow-up compared to baseline. Of all investigated parameters, only SFCT proved to be significant, as a higher baseline SFCT was found to be a strong negative predictor for the number of IVIs needed after SRT (regression coefficient: -0.678; P < .001)., Conclusions: Baseline SFCT may help predict which patients with nAMD will respond more favorably to SRT. The authors found eyes with a thicker baseline SFCT needed fewer IVIs after SRT. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:320-328.]., (Copyright 2018, SLACK Incorporated.)

Aim: The purpose of this paper was to evaluate whether optical coherence tomography angiography (OCT-A) can be used to quantify the vascular changes in radiation maculopathy, and changes in the tumor vasculature in eyes treated with plaque radiotherapy for choroidal melanoma., Methods: In this prospective study, we evaluated 39 Caucasian patients with choroidal melanoma (39 eyes) treated with ruthenium-106 plaque radiotherapy. The patients underwent complete ophthalmic examination, bulbar echography, and OCT-A before and 1 year after treatment., Results: At baseline, the mean best-corrected visual acuity (BCVA) in the affected eyes was 0.35 ± 0.40 logMAR, and the mean tumor thickness was 2.68 ± 0.25 mm at A-scan echography. After treatment, the mean BCVA increased to 0.41 logMAR, the mean tumor thickness decreased to 1.66 ± 0.23 mm, and the tumor basal diameter was significantly reduced (U = 108, p = 0.001). Moreover, the capillary vessel density was significantly lower in all Early Treatment of Diabetic Retinopathy Study sectors, and both the vessel and flow areas were significantly reduced (p = 0.030 and p = 0.001, respectively)., Conclusions: OCT-A is a noninvasive, reliable method with which to quantify the vessel changes in radiation maculopathy and, given the association between vascularization and malignancy, this procedure may be an aid in treatment decision-making and in monitoring the efficacy of treatment., (© 2018 S. Karger AG, Basel.)

Purpose: This study aims to evaluate and standardize the reliability of a mobile laser indirect ophthalmoscope in the induction of choroidal neovascularization (CNV) in a mouse model., Materials & Methods: A diode laser indirect ophthalmoscope was used to induce CNV in pigmented male C57BL/6J mice. Standardization of spot size and laser intensity was determined using different aspheric lenses with increasing laser intensities applied around the optic disc. Development of CNV was evaluated 1, 5, and 14 days post laser application using fluorescein angiography (FA), histology, and choroidal flat mounts stained for the endothelial marker CD31 and FITC-dextran. Correlation between the number of laser hits to the number and size of developed CNV lesions was determined using flat mount choroid staining. The ability of intravitreally injected anti-human and anti-mouse VEGF antibodies to inhibit CNV induced by the mobile laser was evaluated., Results: Laser parameters were standardized on 350 mW for 100 msec, using the 90 diopter lens to accomplish the highest incidence of Bruch's membrane rupture. CNV lesions' formation was validated on days 5 and 14 post laser injury, though FA showed leakage on as early as day 1. The number of laser hits was significantly correlated with the CNV area. CNV growth was successfully inhibited by both anti-human and mouse VEGF antibodies., Conclusion: The mobile laser indirect ophthalmoscope can serve as a feasible and a reliable alternative method for the CNV induction in a mouse model.

The choroid is affected by many factors. One of the factors, change in illumination has been suggested to influence choroidal thickness. However, the effects of bright light before sleep at night on the human eye are not well established. The purpose of this study was to investigate the effects of a high level of illumination in the evening on ocular measurements. Twenty-seven men with myopia spent seven consecutive nights in the sleep laboratory. During the first two nights, subjects were exposed to light at 150 lux between 20:00 and midnight. Then, for five consecutive nights, they were exposed to ambient light at 1000 lux between 20:00 and midnight. Ocular parameters and their diurnal variations were compared between the two periods and the effects of a high level of illumination were analyzed. After subjects were exposed to 1000 lux of illumination, axial length increased with borderline significance (p = 0.064). Macular volume and retinal thickness did not change. However, subfoveal choroidal thickness after exposure to 1000 lux of illumination (245.37 ± 52.84 μm) was significantly lower than that after 150 lux of illumination (268.00 ± 57.10 μm), (p < 0.001). Significant diurnal variations were found in mean keratometry (p = 0.039), intraocular pressure (IOP, p = 0.003), ocular perfusion pressure (OPP, p < 0.0001), macular volume (p = 0.019), and subfoveal choroidal thickness (p < 0.0001). A high level of illumination had significant effects on only IOP and OPP (p = 0.027 and 0.017, respectively). Bright light exposure before sleep at an intensity as high as 1000 lux reduced subfoveal choroidal thickness in healthy young men. In conclusion, diurnal variation in choroidal thickness can be affected by bright light exposure before sleep., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Purpose: Managing juxtapapillary and circumpapillary choroidal melanoma with brachytherapy is challenging because of technical complications with accurate plaque placement and high radiation toxicity given tumor proximity to the optic nerve. We evaluated our center's experience using ultrasound-guided, Iodine (I)-125 notched plaque brachytherapy for treating choroidal melanoma contiguous with (juxtapapillary) and at least partially surrounding the optic disc (circumpapillary)., Methods: All cases of choroidal melanoma treated with I-125 notched plaque brachytherapy at our center from September 2003-December 2013 were retrospectively reviewed. Only patients with ≥18 months of follow-up who had lesions contiguous with the optic disc (0 mm of separation) were included. The tumor apex prescription dose was 85 Gy. Outcomes evaluated included local control, distant metastasis-free survival (DMFS), cancer-specific survival (CSS), overall survival (OS), visual acuity, and radiation toxicity., Results: Thirty-four patients were included with a median follow-up of 44.1 months (range 18.2-129.0). AJCC T-category was T1 in 58.8%, T2 in 26.5%, and T3 in 14.7%. Median circumferential optic disc involvement was 50% (range 10%-100%). Eye retention was achieved in 94.1%. Actuarial 2- and 4-year rates of local recurrence were 3.1% and 7.6%, DMFS were 97.0% and 88.5%, CSS were 97.0% and 92.8%, and OS were 97.0% and 88.9%, respectively. In addition, 23.5% had visual acuity ≥20/200 at last follow-up., Conclusions: I-125 notched plaque brachytherapy provides high eye preservation rates with acceptable longer-term post-treatment visual outcomes. Based on our experience, choroidal melanoma directly contiguous with and partially encasing the optic disc may be effectively treated with this technique.

Purpose: Demonstrate in vivo that controlled and extended release of a low dose of anti-vascular endothelial growth factor (anti-VEGF) from a microsphere-hydrogel drug delivery system (DDS) has a therapeutic effect in a laser-induced rat model of choroidal neovascularization (CNV)., Methods: Anti-VEGF (ranibizumab or aflibercept) was loaded into poly(lactic-co-glycolic acid) microspheres that were then suspended within an injectable poly(N-isopropylacrylamide)-based thermo-responsive hydrogel DDS.The DDS was shown previously to release bioactive anti-VEGF for ~200 days. CNV was induced using an Ar-green laser. The four experimental groups were as follows: (i) non-treated, (ii) drug-free DDS, (iii) anti-VEGF-loaded DDS, and (iv) bolus injection of anti-VEGF. CNV lesion areas were measured based on fluorescein angiograms and quantified using a multi-Otsu thresholding technique. Intraocular pressure (IOP) and dark-adapted electroretinogram (ERG) were also obtained pre- and post-treatment (1, 2, 4, 8, and 12 weeks)., Results: The anti-VEGF-loaded DDS group had significantly smaller (60%) CNV lesion areas than non-treated animals throughout the study. A small transient increase in IOP was seen immediately after injection; however, all IOP measurements at all time points were within the normal range. There were no significant changes in ERG maximal response compared to pre-treatment measurements for the drug-loaded DDS, which suggests no adverse effects on retinal cellular function., Conclusions: The current study demonstrates that the DDS can effectively decrease laser-induced CNV lesions in a murine model. Controlled and extended release from our DDS achieved greater treatment efficacy using an order of magnitude less drug than what is required with bolus administration. This suggests that our DDS may provide a significant advantage in the treatment of posterior segment eye diseases.

Stereotactic radiotherapy (SRT) is a new approach to treat neovascular age-related macular degeneration (nAMD). The INTREPID trial suggested that SRT could reduce the frequency of regular intravitreal injections (IVIs) with antivascular endothelial growth factor drugs, which are necessary to control disease activity. However, the efficacy of SRT in nAMD and resulting morphological changes have not been validated under real-life circumstances, an issue, which we would like to address in this retrospective analysis.Patients who met the INTREPID criteria for best responders were eligible for SRT. A total of 32 eyes of 32 patients were treated. Thereafter, patients were examined monthly for 12 months and received pro re nata IVI of aflibercept or ranibizumab. Outcome measures were: mean number of injections, best-corrected visual acuity, and morphological changes of the outer retina-choroid complex as well as patient safety.Mean number of IVI decreased by almost 50% during the 12 months after SRT compared to the year before, whereas visual acuity increased by one line (logMAR). Morphological evaluation showed that most changes affect outer retinal layers.Stereotactic radiotherapy significantly reduced IVI retreatment in nAMD patients under real-life circumstances. Therefore, SRT might be the first step to stop visual loss as a result of IVI undertreatment, which is a major risk., Competing Interests: The authors have no conflicts of interest to disclose.

Purpose: Thinning of the RPE and the underlying vascular layer, the choroid, is observed with age in many human eye disorders. The reasons for this thinning are ill-defined. Here, we highlight the possible role of T lymphocyte recruitment in choroidoretinal thinning in aged and light-challenged mice., Methods: In age and light challenge models, we measured chemokine concentrations using enzyme-linked immunosorbent assay and used flow cytometry to characterize lymphocyte populations. We quantified thinning in eye immunosections and RPE65 expression using quantitative PCR., Results: Age and light challenge led to increased levels of the lymphotactic protein CXCL10 alone (aging) or in conjunction with CXCL9 (light challenge). Increased numbers of CD3+ T lymphocytes, most of them CD8+ cytotoxic T lymphocytes, were also observed in the choroid and retina of old mice and following light challenge. Influx of T lymphocytes was associated with RPE and choroidal thinning and diminished expression of RPE65 mRNA, an essential enzyme of the visual cycle., Conclusions: The observations from this study suggest that cytotoxic CD8(+) T lymphocytes might participate in choroidal and RPE degeneration and that modulation of T lymphocyte recruitment might be a novel strategy to reduce choroidoretinal dysfunctions observed with age and following photo-oxidative stress.

Background and Objective: Chlorophyllin-M is a new chlorophyll-based derivative photosensitive compound developed by our research group with easy laboratorial synthesis and ideal properties for photodynamic therapy (PDT). It is intended for clinical treatments with simple and low cost techniques and reagents. The objective of this study is to evaluate if intravenous chlorophyllin-M is able to deliver a photosensitizer to rabbit retina and rabbit choroid and promote PDT after ocular irradiation with a 660 nm LASER., Methods: This is a pre-clinical study. Ten eyes of five pigmented Californian rabbits were included in the study. The right eyes served as the treatment group, and the left eyes served as the control group. All eyes had been ophthalmologically evaluated and were considered normal., Results: Ophthalmic exam with anterior biomicroscopy, dilated fundus examination, and fluorescein angiography after the LASER procedure revealed normal anterior segment, retinal and choroid vessels occlusion, lumen narrowing, and capillary non-perfusion in the treated areas, indicating that PDT was successful in the treatment eyes group., Conclusion: The results of this pre-clinical study encourage future studies with this new compound. Chlorophyllin-M may become a new cost-effective agent in the retinal therapeutic arsenal., (© 2015 Wiley Periodicals, Inc.)

Oxidative stress in the retinal pigment epithelium (RPE) is a well-accepted pathogenic change in vision-threatening diseases such as age-related macular degeneration. One source of oxidative stress is excessive light exposure, which causes excessive activation of the visual cycle. Because short wavelength light (blue light) has more energy, it is reported to be more harmful to photoreceptor cells than the other wavelengths of light. However, the biological effect of blue light in the RPE of living animals and the protective effect of a yellow intraocular lens (IOL) material that blocks blue light is still obscure. Therefore, we compared the pathogenic effect in the RPE-choroid complexes of mice exposed to light in a box made of a clear or a yellow IOL material. We measured the level of reactive oxygen species (ROS) using 2', 7'-dichlorodihydrofluorescein diacetate, the mRNA levels of inflammatory cytokines and a macrophage marker by real-time polymerase chain reaction, and the protein level of monocyte chemotactic protein-1 (MCP-1) by ELISA. The ROS level after light exposure was suppressed in the RPE-choroids of light-exposed mice in the yellow IOL material box. In parallel, all the inflammatory cytokines that we measured and a macrophage marker were also suppressed in the RPE-choroids of light-exposed mice in the yellow IOL material box. Therefore, a yellow IOL material suppressed, and thus blue light exacerbated, the increase in the ROS level and inflammatory cytokine expression as well as macrophage recruitment in the RPE-choroid in vivo after light exposure., (Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Purpose: To compare the chorioretinal tissue response after different half-strength parameters of photodynamic therapy (PDT) in rabbits., Methods: The study included 4 groups, and each group contained 4 animals. The full dose served as the control group: verteporfin (4 mg/kg) with 600 mW/cm(2) irradiance from a diode laser at 689 nm applied to the retina for 8 s. One parameter was changed to half-strength in the other 3 groups. The HLaser group received half-strength laser irradiance. The HTime group was exposed to photosensitization for half the time, and the HDose group received half the drug dose. Six laser spots were generated in each of the eyes of every rabbit and documented graphically. The lesions were examined on days 1, 7, and 42 after PDT treatment using color fundus imaging, fluorescein angiography (FA), and histopathology analysis., Results: PDT treatment in rabbits caused chorioretinal damage in all 4 groups. FA on day 1 showed that the use of half the laser irradiance, half the drug dose, or half the photosensitizing time tended to decrease the damage to the chorioretinal tissue in terms of the number of occlusions and the area of occlusion, but only the results from half the laser irradiance were significantly different. In addition, the HLaser and HDose groups showed significantly less apoptosis by TUNEL staining on day 1., Conclusions: Among these PDT parameters, decreasing the laser irradiance by half showed the greatest decrease in chorioretinal damage in an experimental animal model.

Purpose: To determine whether intravitreally-injected baicalin inhibits the growth of choroidal neovascularization (CNV) experimentally induced via laser photocoagulation through analysis of angiogenic factors., Materials and Methods: Six CNVs were induced in the left eyes of 8-week-old male Brown Norway rats. Immediately after the induction of CNV, 4 μl of baicalin solution (0.1, 1 or 5 nmol) and 4 μl of a solution containing 100 μg of bevacizumab were slowly injected into the vitreous cavity under direct observation with an operating microscope. At 14 days after CNV induction, fluorescein angiography (FA) was performed, and choroidal flat mounts were produced for quantitative assessment of CNV. The levels of the anti-angiogenic proteins vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) and matrix metalloproteinase-2 (MMP-2) were determined via Western blot analysis., Results: FA of bevacizumab- and baicalin-treated rats showed significantly reduced CNV and leakage from the CNV lesions compared to control rats at day 14. Choroidal flat mounts revealed that baicalin inhibited the growth of CNV lesions in a dose-dependent manner. Western blot analysis demonstrated that baicalin significantly attenuated the up-regulation of VEGF, PDGF and MMP-2., Conclusion: Baicalin suppressed laser-induced CNV formation in rats. These results suggest that baicalin should be considered as a candidate drug for treating exudative age-related macular degeneration.

It was recently demonstrated that chromaticity could affect eye growth and refractive development in guinea pigs but it remained unclear whether correction with spectacle lenses could balance these effects and how retinal responses change with different spectral compositions of light. Three illumination conditions were tested: blue, red and white light. Animals were raised without or with monocular spectacle lenses from three to seven weeks of age. Luminance electroretinograms (ERGs) were recorded to explore retinal responses with the different spectral compositions. In our special colony of pigmented guinea pigs, characterized by residual hyperopia, spontaneous myopia and poor emmetropization, red light induced early thinning of the choroid and relative myopia, compared to white light. Effects of red light could not be suppressed if positive spectacle lenses were worn. ERGs showed that red light failed to elicit robust retinal responses. Blue light inhibited axial eye growth, even when animals were reared with negative lenses. Intensity-matched blue and white light elicited similar a-waves but different b-waves, suggesting that the wavelength of light affects visual control of eye growth through different processing in the inner retina. We hypothesize that blue light might stimulate preferentially the ON pathway to inhibit myopia induced by negative lenses, at least in guinea pigs., (Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.)

Purpose: Bright light is a potent inhibitor of myopia development in animal models. Because development of refractive errors has been linked to changes in choroidal thickness, we have studied in chickens whether bright light may exert its effects on myopia also through changes in choroidal thickness., Methods: Three-day-old chickens were exposed to "bright light" (15,000 lux; n = 14) from 10 AM to 4 PM but kept under "normal light" (500 lux) during the remaining time of the light phase for 5 days (total duration of light phase 8 AM to 6 PM). A control group (n = 14) was kept under normal light during the entire light phase. Choroidal thickness was measured in alert, hand-held animals with optical coherence tomography at 10 AM, 4 PM, and 8 PM every day., Results: Complete data sets were available for 12 chicks in bright light group and nine in normal light group. The striking inter-individual variability in choroidal thickness (coefficient of variance: 23%) made it necessary to normalize changes to the individual baseline thickness of the choroid. During the 6 hours of exposure to bright light, choroidal thickness decreased by -5.2 ± 4.0% (mean ± SEM). By contrast, in the group kept under normal light, choroidal thickness increased by +15.4 ± 4.7% (difference between both groups p = 0.003). After an additional 4 hours, choroidal thickness increased also in the "bright light group" by +17.8 ± 3.5%, while there was little further change (+0.6 ± 4.0%) in the "normal light group" (difference p = 0.004). Finally, the choroid was thicker in the "bright light group" (+7.6 ± 26.0%) than in the "normal light group" (day 5: -18.6 ± 26.9%; difference p = 0.036)., Conclusions: Bright light stimulates choroidal thickening in chickens, although the response is smaller than with experimentally imposed myopic defocus, and it occurs with some time delay. It nevertheless suggests that choroidal thickening is also involved in myopia inhibition by bright light.

We review the cellular and physiological mechanisms responsible for the regulation of blood flow in the retina and choroid in health and disease. Due to the intrinsic light sensitivity of the retina and the direct visual accessibility of fundus blood vessels, the eye offers unique opportunities for the non-invasive investigation of mechanisms of blood flow regulation. The ability of the retinal vasculature to regulate its blood flow is contrasted with the far more restricted ability of the choroidal circulation to regulate its blood flow by virtue of the absence of glial cells, the markedly reduced pericyte ensheathment of the choroidal vasculature, and the lack of intermediate filaments in choroidal pericytes. We review the cellular and molecular components of the neurovascular unit in the retina and choroid, techniques for monitoring retinal and choroidal blood flow, responses of the retinal and choroidal circulation to light stimulation, the role of capillaries, astrocytes and pericytes in regulating blood flow, putative signaling mechanisms mediating neurovascular coupling in the retina, and changes that occur in the retinal and choroidal circulation during diabetic retinopathy, age-related macular degeneration, glaucoma, and Alzheimer's disease. We close by discussing issues that remain to be explored., (Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.)

The induced thermal damage in retinal photocoagulation depends on the temperature increase and the time of irradiation. The temperature rise is unknown due to intraocular variations in light transmission, scattering and grade of absorption in the retinal pigment epithelium (RPE) and the choroid. Thus, in clinical practice, often stronger and deeper coagulations are applied than therapeutically needed, which can lead to extended neuroretinal damage and strong pain perception. This work focuses on an optoacoustic (OA) method to determine the temperature rise in real-time during photocoagulation by repetitively exciting thermoelastic pressure transients with nanosecond probe laser pulses, which are simultaneously applied to the treatment radiation. The temperature-dependent pressure amplitudes are non-invasively detected at the cornea with an ultrasonic transducer embedded in the contact lens. During clinical treatment, temperature courses as predicted by heat diffusion theory are observed in most cases. For laser spot diameters of 100 and 300 μm, and irradiation times of 100 and 200 ms, respectively, peak temperatures range between 70°C and 85°C for mild coagulations. The obtained data look very promising for the realization of a feedback-controlled treatment, which automatically generates preselected and reproducible coagulation strengths, unburdens the ophthalmologist from manual laser dosage, and minimizes adverse effects and pain for the patient.

Retinopathy is a surgical process in which maladies of the human eye are treated by laser irradiation. A two-dimensional numerical model of the human eye geometry has been developed to investigate transient thermal effects due to laser radiation. In particular, the influence of choroidal pigmentation and that of choroidal blood convection-parameterized as a function of choroidal blood perfusion-are investigated in detail. The Pennes bio-heat transfer equation is invoked as the governing equation, and finite volume formulation is employed in the numerical method. For a 500-μm diameter spot size, laser power of 0.2 W, and 100% absorption of laser radiation in the retinal pigmented epithelium (RPE) region, the peak RPE temperature is observed to be 103 °C at 100 ms of the transient simulation of the laser surgical period. Because of the participation of pigmented layer of choroid in laser absorption, peak temperature is reduced to 94 °C after 100 ms of the laser surgery period. The effect of choroidal blood perfusion on retinal cooling is found to be negligible during transient simulation of retinopathy. A truncated three-dimensional model incorporating multiple laser irradiation of spots is also developed to observe the spatial effect of choroidal blood perfusion and choroidal pigmentation. For a circular array of seven uniformly distributed spots of identical diameter and laser power of 0.2 W, transient temperature evolution using simultaneous and sequential mode of laser surgical process is presented with analysis., (Copyright © 2012 John Wiley & Sons, Ltd.)

Purpose: To clarify the association between cluster of differentiation 36 (CD36) gene polymorphisms and the response to photodynamic therapy (PDT) in polypoidal choroidal vasculopathy (PCV)., Methods: One hundred and thirty-seven patients with PCV were enrolled. The patients were treated with PDT and followed up for more than 6 months. Retreatments were performed every 3 months as needed based on findings from angiography. Patients who showed an improvement in their best-corrected visual acuity at 6 months post-PDT were classified as PDT responders, and the others were defined as non-responders. For the 73 responders and 64 non-responders, 19 single nucleotide polymorphisms (SNPs) across the CD36 region were genotyped using the TaqMan assay. We analyzed the association between these variants and the visual outcomes of PDT., Results: The allelic frequencies of the SNPs rs3211851, rs3173798, and rs3211908 showed nominally significant differences between the PDT responders and non-responders. Genotype association analysis revealed a significant association of SNP rs3173798 with the visual outcome of PDT in a dominant model. The presence of the C allele in rs3173798 was significantly associated with a poor response to PDT after multivariate logistic regression analysis with clinical pre-PDT parameters. The mean best-corrected visual acuity in the group with the TT genotype of rs3173798 was significantly improved over 12 months of follow-up after the initial PDT., Conclusions: The coding variants in CD36 are possibly associated with the visual outcome of PDT in patients with PCV.

Purpose: To investigate the biologic effect of an 810 nm diode laser on the induction of heat shock protein 70 (Hsp70) in choroid-retinal endothelial cells in vitro., Methods: Cultured rhesus macaque choroid-retinal endothelial cells (RF/6A) were irradiated using an 810 nm diode laser (spot size, 10 mm; duration, 60 s; power, 400-1,500 mW). Cell viability was assessed by annexin V- fluorescein isothiocyanate (FITC) and propidium iodide flow cytometric assay. Hsp70 expression was determined by western blot at 6, 12, 18, 24, and 48 h following laser exposure. Intracellular distribution of Hsp70 was examined by immunofluorescence staining., Results: The laser-induced cell injury threshold was found to be at a power of 1,100 mW power (fluence, 84.08 J/cm(2)), above which there was significant cell death. Under this power, Hsp70 expression elevated obviously and was stronger at 600-1,000 mW power settings (fluences, 45.86-76.43 J/cm(2)). The expression of Hsp70 peaked at 12-18 h postirradiation, and returned to baseline by 48 h. Immunofluorescence staining indicated the induced Hsp70 expression in both the cytoplasm and the nucleus., Conclusions: Subthreshold 810 nm diode laser exposure can induce Hsp70 hyperexpression from 12 to 18 h postirradiation in cultured choroid-retinal endothelial cells without obvious cell death. The results could be useful for investigating and designing more effective laser therapies.

The influence of several subthreshold laser procedures on chorioretinal complex (CRC) tissues was experimentally studied in rabbits using histological and histochemical methods. Subthreshold micropulse laser radiation and transpupillar thermotherapy were found to have the most attenuated and advantageous effect on CRC structure. The feature of subthreshold laser exposure is partly reversible selective changes in CRC, that have temporary stimulating effect on cellular metabolism and local regenerative processes providing an opportunity for still viable tissues to function adequately.

Background: Histological findings of choroidal melanomas after proton beam irradiation have been reported for complicated cases after enucleation. We present specimens of a tumor after transretinal probe excision., Patient and Methods: One year after irradiation, the biopsy was examined histologically., Results: The specimens showed pigmented, spindle-shaped cells staining positively for Melan-A and HMB-45. Ki-67 showed low proliferation. Caspase-3 staining was normal., Conclusions: The melanoma still contained vital and even single proliferating cells, but regressed afterwards without additional therapy.

Objective: The objective of this study was to compare the reduction in size of experimentally induced choroidal neovascularization (CNV) in rat eyes treated with bevacizumab, poly(ethylene-glycol) (PEG)-bevacizumab conjugate (b-PEG), and poly(lactic-co-glycolic acid) (PLGA)-encapsulated bevacizumab (b-PLGA)., Methods: Forty-eight eyes from 24 rats were divided into 4 groups of 12 eyes. In each group, 3 eyes were assigned to a treatment subgroup, each receiving a different injection-control, bevacizumab, b-PEG, and b-PLGA. In all eyes, laser photocoagulation was used to rupture Bruch's membrane. In group 1, laser was followed by injection, which was then followed by harvesting the rats to assess the CNV area. All 3 steps were separated by a 2-week interval. In groups 2, 3, and 4, injection preceded laser photocoagulation by a variable interval and all rats were harvested 2 weeks postlaser treatment. In group 2, laser and injection were separated by 2 weeks. In group 3, laser followed injection by 4 weeks. In group 4, laser followed injection by 6 weeks. The CNV area was measured for each subgroup and compared against its control. Pairwise comparisons were conducted to assess for statistically significant differences between subgroups., Results: All subgroups in groups 1, 2, and 4 showed statistically significant reduction of CNV area (P<0.05). In group 3, the b-PEG and b-PLGA subgroups showed a 9.0% (P=0.384) and 20.3% (P=0.077) reduction in CNV area versus control, whereas there was no reduction in CNV area in the bevacizumab subgroup. However, this was not found to be statistically significant. In group 4, b-PEG was more effective than bevacizumab and b-PLGA., Conclusion: The reduction in CNV area in all treatment subgroups, with the exception of those in group 3, suggests successful creation of the 2 bevacizumab formulations while retaining its active antiangiogenic properties. Further studies varying in dosages and timing of injection and laser are needed to evaluate the formulations' long-acting efficacy.

Purpose: Focal epiretinal radiation has emerged as a promising tool in the management of choroidal neovascularization associated with age-related macular degeneration. However, the dosages tested are not backed by cell culture studies used in the clinical setting empirically., Methods: Choroidal endothelial cells (RF6A) were maintained in a log scale and exposed to a single fraction of 2, 4, 8, and 12 cobalt gray-equivalent of proton radiation with an internal control. Cell viability was quantified using Vi-cell XR and neutral red assay at days 5, 9, and 12 after radiation. Mitochondrial viability using WST-1 and reactive oxygen species levels using dihydrorhodamine 123 were measured at similar intervals., Results: By using neutral red assay, on day 12, the percentages of viable cells compared with control were 100.1 ± 5.7%, 96.7 ± 23.3%, 27.6 ± 6.6%, and 19.5 ± 3% at radiation doses of 2, 4, 8, and 12 cobalt gray-equivalent, respectively (P < 0.001). Increase in reactive oxygen species levels correlated with the number of dead cells implicating reactive oxygen species as an intermediary molecule (r = 0.85-0.96)., Conclusion: Our study shows sensitivity of cultured choroidal endothelial cells to proton beam radiation at doses of 8 and 12 cobalt gray-equivalent in an in vitro model.

Purpose: The retinal pigment epithelium (RPE) plays an important role in the maintenance of the health and function of photoreceptors. Previous studies have shown that the RPE is also involved in the regulation of disc shedding, a process that is vital for photoreceptor health. This process has been shown to be under circadian control, although the mechanisms that control it are poorly understood. The aim of the present study was to investigate Period 2 (Per2) mRNA levels in the mouse RPE in vivo, and to determine whether the cultured RPE-choroid from PERIOD 2::LUCIFERASE (PER2::LUC) knockin mice expresses a circadian rhythm in bioluminescence., Methods: Per2 mRNA levels were measured using real-time quantitative RT-PCR, and bioluminescence was measured in PER2::LUC knockin mice using a Lumicycle®., Results: Per2 mRNA levels in the RPE-choroid show a clear circadian rhythm in vivo. A circadian rhythm in PER2::LUC bioluminescence was recorded from cultured RPE-choroid explants. Light exposure during the subjective night did not cause a circadian rhythm phase-shift of PER2::LUC bioluminescence. Finally, removal of the suprachiasmatic nuclei of the hypothalamus did not affect the bioluminescence circadian rhythm in the RPE-choroid., Conclusions: Our results demonstrate that the RPE-choroid contains a circadian clock, and the regulation of this circadian rhythm resides within the eye. These new data indicate that it may be useful to design studies with the aim of elucidating the molecular mechanisms responsible for the regulation of the rhythmic event in the RPE.

New and more precise subretinal surgical techniques would be useful in a range of retinal diseases. The purpose of this study is to determine the feasibility of using fiberoptically delivered ultraviolet laser energy to transect or ablate subretinal tissues. Choroid segments dissected from fresh porcine eyes, with or without the retinal pigment epithelium (RPE), were clamped in a fluid bath. Pulsed fourth harmonic (266 nm) of a Nd:YAG laser radiation was delivered via an optical fiber probe at fluence levels between 0.08 and 0.40 J/cm(2). The tissue was then fixed and sectioned for histological examination. Radiation induced damage was categorized by the degree of tissue disruption and ablation depth. Tissue ablation and the severity of the tissue injury varied with both tissue properties and applied laser parameters. Disruption of Bruch's membrane was typically induced by 10 pulses of 0.30 J/cm(2) or 2 pulses of 0.40 J/cm(2). Lower radiation doses did not disrupt Bruch's membrane, but did damage the choroidal tissue and produce vacuoles in the underlying choroid. The full thickness of the choroid was ablated by 200 pulses of 0.40 J/cm(2). The presence of the RPE produced a shielding effect which was greater than would be expected for an equivalent thickness of choroidal tissue. Ablation characteristics of subretinal tissue are highly dependent on the laser parameters used and the type of tissue involved. To perform well controlled laser surgery on subretinal tissues both laser parameters and the properties of the target cells and tissues have to be considered., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Aim: To study alterations in choroidal blood flow (CBF) in the foveal region after panretinal photocoagulation (PRP) in patients with severe proliferative diabetic retinopathy., Methods: Seventeen eyes of 17 patients with severe non-proliferative diabetic retinopathy (PDR) or with non-high-risk PDR and no macular oedema before PRP were included. All patients underwent four sessions of scatter PRP. We measured the choroidal blood velocity (CBVel), choroidal blood volume (CBVol) and CBF in the foveal region before and 1 month after PRP using a laser Doppler flowmetry., Results: Macular oedema did not develop after PRP in any treated eyes. One month after PRP, there was no significant change in the mean CBVel (311.2 (SD 61.2) Hz) compared with baseline (327.1 (74.1) Hz) (p = 0.17). In contrast, the mean CBVol and CBF values increased significantly by 51% (from 0.37 (0.12) arbitrary units (au) at baseline to 0.52 (0.16) au, p = 0.0025) and 46% (from 7.3 (2.4) au at baseline to 10.4 (4.4) au, p = 0.0014), respectively, 1 month after PRP., Conclusion: These results indicate that PRP may increase the CBF in the foveal region in eyes with severe diabetic retinopathy. The current results may be caused by vasodilation of the choriocapillaries in the foveal region.

Fractionated stereotactic radiation has become the standard treatment of meningioma of the optic nerve sheath. The mechanism responsible for improvement in visual function is unclear, because neuroimaging after treatment usually shows no discernable change in tumor appearance. We report immediate regression of optociliary shunt vessels in a patient after radiation treatment of an optic nerve sheath meningioma. This observation indicates that radiation treatment can cause rapid reduction of optic nerve compression, even without appreciable reduction in the size of the meningioma.

Background: A wide variety of pathological pathways may result in age-related macular degeneration. Because of its complexity, there is no comprehensive model of the disease yet. One key feature is the accumulation of the autofluorescent pigment lipofuscin in the retinal pigment epithelium (RPE). Thus, we developed an organotypic perfusion culture model of the porcine ocular fundus, generating lipofuscin under exposure to blue light and hydrogen peroxide., Methods: Porcine fundi (choroid, Bruch's membrane, RPE, and retina) were explanted in toto, transferred into a perfusion culture chamber, perfused with cell culture medium and kept at 37 degrees C. Free radical stress was induced by supplementation of H(2)O(2), and/or the specimens were exposed to blue light, or kept untreated as controls. After a culture period of 7 days, the specimens were subject to microscopic inspection, histology, fluorescence microscopy, and measurement of fluorescence spectra as well as fluorescence decay times., Results: Histology showed atrophic ganglion cells and rod outer segments. All other tissue structures were morphologically intact. Compared to the controls, RPE and retina exposed to light showed increased fluorescence, which was shifted towards shorter wavelengths. The fluorescence spectra and decays resembled that of lipofuscin granules isolated from human donor eyes. HPLC analysis revealed the abundance of the lipofuscin component N-retinylidene-N-retinylethanolamine (A2E), its precursor products, as well as two new, green-emitting fluorophores., Conclusions: Porcine ocular fundi were successfully preserved in an organotypic perfusion culture for 7 days, and exhibited remarkable autofluorescence after light and free radical exposure, making the model suitable for investigations of lipofuscinogenesis.

Purpose: Our objective was to comprehensively assess the nature and chronology of neural remodeling in retinal degenerations triggered by light-induced retinal damage (LIRD) in adult albino rodents. Our primary hypothesis is that all complete photoreceptor degenerations devolve to extensive remodeling. An hypothesis emergent from data analysis is that the LIRD model closely mimics late-stage atrophic age relared macular degeneration (AMD)., Methods: Sprague-Dawley (SD) rats received intense light exposures of varied durations and survival times ranging from 0 to 240 days. Remodeling was visualized by computational molecular phenotyping (CMP) of a small molecule library: 4-aminobutyrate (gamma), arginine (R), aspartate (D), glutamate (E), glutamine (Q), glutathione (J), glycine (G), and taurine (tau). This library was augmented by probes for key proteins such as rod opsin, cone opsin and cellular retinal binding protein (CRALBP). Quantitative CMP was used to profile 160 eyes from 86 animals in over 6,000 sections., Results: The onset of remodeling in LIRD retinas is rapid, with immediate signs of metabolic stress in photoreceptors, the retinal pigmented epithelium (RPE), the choriocapillaris, and Müller cells. In particular, anomalous elevated aspartate levels appear to be an early stress marker in photoreceptors. After the stress phase, LIRD progresses to focal photoreceptor degeneration within 14 days and extensive remodeling by 60 days. RPE and choriocapillaris losses parallel Müller cell distal seal formation, with progressive neuronal migration, microneuroma evolution, fluid channel formation, and slow neuronal death. The remaining retina in advanced light damage can be classified as survivor, light damage (LD), or decimated zones where massive Müller cell and neuronal emigration into the choroid leaves a retina depleted of neurons and Müller cells. These zones and their transitions closely resemble human geographic atrophy. Across these zones, Müller cells manifest extreme changes in the definitive Müller cell tauQE signature, as well as CRALBP and arginine signals., Conclusions: LIRD retinas manifest remodeling patterns of genetic retinal degeneration models, but involve no developmental complexities, and are ultimately more aggressive, devastating the remaining neural retina. The decimation of the neural retina via cell emigration through the perforated retina-choroid interface is a serious denouement. If focal remodeling in LIRD accurately profiles late stage atrophic age-related macular degenerations, it augurs poorly for simple molecular interventions. Indeed, the LIRD profile in the SD rat manifests more similarities to advanced human atrophic AMD than most genetically or immunologically induced murine models of AMD.

Selective thermal treatment to retina is induced by short pulsed lasers to denaturize retinal pigment epithelium (RPE) selectively, while sparing the sensitive photoreceptors. The problem associated with the usage of short pulsed laser is the difficulty in determining the correct dosimetry parameters. This study quantifies the influence of laser parameters over the therapeutic range. The laser-tissue interaction is numerically investigated by analyzing the transient temperature in ocular tissues during the treatment. The rate process analysis for thermal injury is employed to estimate the selective damage of retina. The contours of Arrhenius integral value (Omeg/ Omegamax) presented in this study show both the area and magnitude of damage caused by various laser parameters. Results reveal that the 2 micros pulsed laser with green wavelength and Gaussian profile is relatively more effective for selective retinal treatment. The repetition frequency of 100 Hz is found to produce selectively RPE damage, while higher frequencies produce collateral damage to neural retina and choroid located within 2 microm from the RPE interface.

Purpose: To report two cases of atypical late onset radiation chorioretinopathy occurring 15 and 25 years post exposure and the indocyanine green (ICG) angiographic findings in these patients., Methods: Clinical examination and imaging including fluorescein and ICG angiography were performed., Result: Fundus examination of the first patient revealed microangiopathy with intraretinal hemorrhages, lipid exudation, telangiectatic and aneurysmal capillary changes. Indocyanine green angiography showed an apparent chorioretinal anastomosis and delayed perfusion of the choriocapillaris. Fundus examination of the second patient revealed a pigment epithelial detachment and retinal pigment epithelial changes. Indocyanine green angiography showed atypical, tortuous, dilated, choroidal vessels as well as areas of hypoperfusion. Both patients had multiple dot-like hyperfluorescent spots in the midphase of the ICG angiogram., Conclusions: External radiation exposure may lead to both retinal and choroidal alterations which may be independent events and which may manifest after a long period of quiescence. Furthermore, ICG angiography appears to be a useful diagnostic tool to study the alterations of the choroid following external eye irradiation.

Purpose: To describe the characteristics and evolution of pigmented episcleral deposits after brachytherapy for uveal melanoma to determine their origin and association with melanoma-related mortality., Design: Noncomparative case series., Participants: Two hundred eleven patients (108 males, 103 females; median age, 61 years; range, 14-88 years) who were treated with a single ruthenium and iodine plaque therapy (median dose to tumor base, 475 Gy and 392 Gy, respectively) for a choroidal and ciliary body melanoma. Median tumor diameter and height were 12 mm and 5.5 mm, respectively. Eighty-eight patients were treated prospectively during the study., Methods: The number and location of pigmented episcleral deposits were recorded under the slit lamp during each visit after brachytherapy. The association of the deposits with tumor characteristics and survival was analyzed with logistic regression and Kaplan-Meier analysis, respectively., Main Outcome Measures: Number and location of episcleral deposits, melanoma-related mortality., Results: The pigmented episcleral deposits ranged from black and brownish spots to slightly thickened patches. Most deposits appeared within the first 6 months after brachytherapy. By 1 year, 85% (95% confidence interval, 77-93) of eyes had at least 1 deposit (median, 6). The deposits increased in number until 7 years from irradiation, and decreased with increasing distance from tumor center. An association between the number of deposits at 1 and 2 years and subsequent melanoma-related mortality could not be confirmed (P = 0.80 and P = 0.31, respectively)., Conclusions: Pigmented macrophage-related episcleral deposits are found in most eyes with uveal melanoma after brachytherapy. Their association with plaque size and isotope rather than with tumor size suggests that radiation atrophy of retinal pigment epithelium and choroid in addition to tumor regression contributes to the formation of the deposits. Knowledge of their existence may save patients from unnecessary enucleation.

The initial events of angiogenesis comprise endothelial cell activation, migration, and proliferation. The characteristics of retinal endothelial cells and capillaries are significantly altered in a number of diseases including cancer. Since radiation has been shown as a useful tool in radiotherapy by altering the proliferative changes, it is important to evaluate the responses of the endothelial cells and the capillary network to radiation. We quantified functional and kinetic responses of endothelial cells and capillaries to radiation in an in vitro model. An in vitro angiogenesis model was introduced in our study with endothelial cells cultured on an extracellular matrix gel in which hollow tube-like structures could be rapidly formed. Vessel formation was quantified using stereological techniques. The cell cycle kinetics of endothelial cells and accumulation of DNA damage after radiation were measured using laser scanning cytometry. To study the response of proliferative capillary-like structures to radiation, the vessel network was irradiated with 2 gray (Gy). To evaluate functional and kinetic responses and differentiation of endothelial cells to radiation, cells were irradiated with 2 and 6 Gy. Progressive time- and dose-dependent loss of endothelial cells occurred starting 24 hours after radiation. Vessel growth was significantly retarded at the higher dose. A significant percentage of DNA breaks were detected dose-dependently. A large percentage of G1 cells were measured in the irradiated endothelial cell population when compared to the respective sham-treated control population. These results indicate that radiation-induced endothelial cell injuries destroy the integrity of vascular structure. We postulated that apoptosis may represent a biologically relevant mechanism of radiation-induced endothelial cell damage.

Seventy-five patients (75 eyes) with central involution chorioretinal dystrophy (non-exudative type at the progression stage) were followed up. All of them received low-intensity laser therapy. Irradiation of 890 nm, 644 nm and 500 nm was used in groups 1, 2 and 3, respectively. The study purpose was to compare the efficiency of wavelengths. Visual acuity and retinal sensitivity were determined. The results were evaluated immediately after treatment and in 3 months. The maximal improvement in visual acuity and retinal sensitivity was in those who received 890 nm laser therapy; 500 nm irradiation--a less pronounced effect and 640 nm--the lowest one. We attribute such distribution of efficiency to a proliferation type of each irradiation range in the macular zone.

Exposure to high-intensity light led to pronounced destructive changes in the retina and focal loss of layers formed by neurosensory cells in rats. Photoinjury led to progressive decrease in the numerical density of nuclei in the outer nuclear layer (by 30% after 2 days, by 75% after 1 week, and more than by 90% after 2 weeks of exposure). After 30 days the photosensory layer completely disappeared, while the outer nuclear layer was presented by solitary nuclei of neurosensory cells.

Purpose: To develop a technique for noninvasive and real-time monitoring of chorioretinal temperature in transpupillary thermotherapy (TTT)., Method: A modified slit lamp, which was equipped with two laser wavelengths (490 nm for illumination and fluorescein excitation and 810 nm for hyperthermia), was developed for TTT and temperature monitoring. Five types of liposomes were prepared, and their phase-transition temperatures were 40 degrees C, 46 degrees C, 47 degrees C, 48 degrees C, and 52 degrees C, respectively. Carboxyfluorescein was encapsulated in each liposome. After intravenous injection of each liposome, TTT with the modified slit lamp was performed on normal rat choroid or tissue with choroidal neovascularization (CNV). During TTT, chorioretinal temperature was monitored by observing release of fluorescein from circulating liposomes., Results: Fluorescence from liposomes was initially observed around the heated lesion immediately after TTT began and disappeared rapidly when irradiation stopped. Choroidal and retinal temperatures were monitored separately. TTT for normal retina required higher power than that for normal choroid to observe fluorescence from a 40 degrees C, 46 degrees C, and 47 degrees C liposome. Retinal whitening was observed after TTT at a high-power setting. TTT for CNV required higher laser power than that for the normal choroid and retina., Conclusions: The results demonstrate the potential use of a noninvasive monitoring technique of chorioretinal temperature during TTT. The method should be useful to establish the TTT setting and achieve the optimal temperature increase in CNV.