Deep learning-based correction of cataract-induced influence on macular pigment optical density measurement by autofluorescence spectroscopy

PURPOSE

Measurements of macular pigment optical density (MPOD) using the autofluorescence spectroscopy yield underestimations of actual values in eyes with cataracts. Previously, we proposed a correction method for this error using deep learning (DL); however, the correction performance was validated through internal cross-validation. This cross-sectional study aimed to validate this approach using an external validation dataset.

METHODS

MPODs at 0.25°, 0.5°, 1°, and 2° eccentricities and macular pigment optical volume (MPOV) within 9° eccentricity were measured using SPECTRALIS (Heidelberg Engineering, Heidelberg, Germany) in 197 (training dataset inherited from our previous study) and 157 eyes (validating dataset) before and after cataract surgery. A DL model was trained to predict the corrected value from the pre-operative value using the training dataset, and we measured the discrepancy between the corrected value and the actual postoperative value. Subsequently, the prediction performance was validated using a validation dataset.

RESULTS

Using the validation dataset, the mean absolute values of errors for MPOD and MPOV corrected using DL ranged from 8.2 to 12.4%, which were lower than values with no correction (P < 0.001, linear mixed model with Tukey's test). The error depended on the autofluorescence image quality used to calculate MPOD. The mean errors in high and moderate quality images ranged from 6.0 to 11.4%, which were lower than those of poor quality images.

CONCLUSION

The usefulness of the DL correction method was validated. Deep learning reduced the error for a relatively good autofluorescence image quality. Poor-quality images were not corrected.

Inter-device concordance of Veggie Meter, a reflection spectroscopy to measure skin carotenoids

The Veggie Meter® (VM) is a refraction spectrometer that detects skin carotenoids. We tested the variability of the two modes (single-scan and averaging modes) of four VMs of three different versions (VM-1, 2, 3, 4) with 92 healthy volunteers. Both the modes exhibited a high intraclass correlation coefficient; however, the averaging mode had a significantly lower coefficient of variance than the single-scan mode. The Bland-Altman analysis showed a systematic error between VM-1 and other three VMs. The actual errors between the VM-1 and the other three VMs in the averaging mode were 7.4, 10.4, and 11.8% of the median of VM scores, but the errors could be reduced to 2.8, 6.3, and 7.0% by compensating VM scores using the regression equations. Averaging mode had higher accuracy than single-scan mode. The reliability of the VMs was validated by the small CV and high ICC. The error was improved using linear regression compensation.

Correction for the Influence of Cataract on Macular Pigment Measurement by Autofluorescence Technique Using Deep Learning

Purpose

Measurements of macular pigment optical density (MPOD) by the autofluorescence technique yield underestimations of actual values in eyes with cataract. We applied deep learning (DL) to correct this error.

Subjects and Methods

MPOD was measured by SPECTRALIS (Heidelberg Engineering, Heidelberg, Germany) in 197 eyes before and after cataract surgery. The nominal MPOD values (= preoperative value) were corrected by three methods: the regression equation (RE) method, subjective classification (SC) method (described in our previous study), and DL method. The errors between the corrected and true values (= postoperative value) were calculated for local MPODs at 0.25°, 0.5°, 1°, and 2° eccentricities and macular pigment optical volume (MPOV) within 9° eccentricity.

Results

The mean error for MPODs at four eccentricities was 32% without any correction, 15% with correction by RE, 16% with correction by SC, and 14% with correction by DL. The mean error for MPOV was 21% without correction and 14%, 10%, and 10%, respectively, with correction by the same methods. The errors with any correction were significantly lower than those without correction (P < 0.001, linear mixed model with Tukey's test). The errors with DL correction were significantly lower than those with RE correction in MPOD at 1° eccentricity and MPOV (P < 0.001) and were equivalent to those with SC correction.

Conclusions

The objective method using DL was useful to correct MPOD values measured in aged people.

Translational Relevance

MPOD can be obtained with small errors in eyes with cataract using DL.

Macular pigment changes after cataract surgery with yellow-tinted intraocular lens implantation

Purpose

We previously reported that macular pigment optical density (MPOD) levels decreased during a long follow-up period after clear intraocular lens (IOL) implant surgery presumably due to excessive light exposure. We examined changes in MPOD levels in the eyes that received yellow-tinted IOL implant surgery.

Subjects and methods

This was a prospective, observational study. Fifty-five eyes of 35 patients were studied. MPOD levels were measured with a dual-wavelength autofluorescence technique on day 4; months 1, 3, and 6; and years 1 and 2 postoperatively. The average optical densities at 0°- 2° eccentricities (local MPODs) and total volumes of MPOD (MPOVs) in the area within 1.5° and 9° eccentricities were analyzed.

Results

The mean local MPOD at baseline (on day 4) was 0.79 at 0°, 0.71 at 0.5°, 0.68 at 0.9°, and 0.32 at 2°. The mean MPOV within 1.5° and 9° at baseline was 2950 and 18,897, respectively. Local MPOD at 0.9° and 2° and MPOVs were slightly decreased at month 1 and increased after that. The increase reached statistical significance in local MPOD at 0.5° and 2° and MPOVs (Tukey–Kramer test). The changes in MPOV within 9° at year 2 [(MPOV on year 2 − MPOV on day 4) / MPOV on day 4] were from −0.21 to 1.18 (mean and standard deviation: 1.14 ± 0.28). The MPOV of 15 eyes increased more than 10% from the initial value, was maintained within 10% in 21 eyes, and deteriorated more than 10% in only 3 eyes.

Conclusions

Local MPOD and MPOV tended to slightly decrease month 1 postoperatively and gradually increased after that, but the rates of increases in MPOD levels were small. Yellow-tinted IOLs that have a lower transmittance of blue light might be preferable for preserving MPOD levels after surgery.

Macular Pigment in Eyes With Macular Hole Formation and Its Change After Surgery

Purpose

To observe the macular pigment (MP) appearances in eyes with macular hole (MH) and clarify the origin of the appearances. The mechanisms underlying the development of MH are discussed based on the observation of MP.

Methods

This observational case series included 33 eyes of 31 patients with MH who underwent vitrectomy. The MP optical density was measured using the two-wavelength fundus autofluorescence technique. The exact localization of MP was evaluated by comparing MP distribution images and optical coherent tomography B-scan images.

Results

MP was missing at the MH. The area of the MP defect corresponded with the area of the defect of outer plexiform layer. MP was present in the retinal flap in stage 2 MH that included glia (Müller cells) and plexiform layers and in the operculum in stage 3 MH, which mainly comprised Müller cells. Cystic spaces in the outer plexiform layer surrounding stage 3 and 4 MHs showed a honeycomb appearance on MP images. MP reappeared to form an irregularly shaped pigment plane after surgical closure of MH. The MP optical volume did not change before and after surgery. Fellow eyes with a central dip in MP distribution subsequently developed MH.

Conclusions

The characteristic appearances of MP at the MH were attributed to MP in the plexiform layers and Müller cell cones. A central dip of MP distribution might be a sign of Müller cell cone damage that proceeds with MH formation.

Translational Relevance

Observation of MP was useful for understanding the mechanisms of MH formation.

Advanced Glycation End Product Accumulation in Subjects with Open-Angle Glaucoma with and without Exfoliation

Advanced glycation end products (AGEs), which are the products of a non-enzymatic reaction between reducing sugars and other macromolecules, are critical in aging, as well as metabolic and degenerative diseases. To assess the involvement of AGEs in glaucoma, skin autofluorescence (sAF) level, which is a measurement of AGEs' accumulation, was compared among Japanese patients with glaucoma (316 with primary open-angle glaucoma (PG) and 127 exfoliation syndrome and glaucoma (EG)) and controls (133 nonglaucomatous controls) (mean age 71.6 ± 12.8 years, 254 men and 322 women). The sAF values were estimated from the middle fingertip using a 365 nm light-emitting diode for excitation and detection at 440 nm emission light. The estimated AGE values (arbitrary unit) were 0.56 ± 0.15, 0.56 ± 0.11, and 0.61 ± 0.11 in the control, PG, and EG groups, respectively (p < 0.0001, analysis of variance); and were significantly higher in the EG group than the control (p = 0.0007) and PG (p < 0.0001) groups. After adjustment for various demographic parameters by multivariate analyses, male sex (standard β = 0.23), EG (0.19), and diabetes (0.09) were associated with higher AGE levels; PG (-0.18) and smoking (-0.19) were associated with lower AGE levels. Age, visual acuity, intraocular pressure, glaucoma medications, lens status, and systemic hypertension were not associated with AGEs. The high AGE level in EG suggested that specific oxidation and glycation mechanisms underlie the glaucoma pathogenesis associated with pseudoexfoliation syndrome.

Potential roles of MNREAD acuity charts and contrast/glare sensitivity in Ranibizumab treatment of branch retinal vein occlusion

Background/Objectives

To investigate the potential utility of MNREAD acuity charts and contrast/glare sensitivity (CGS) assessment for evaluating the efficacy of an initial treatment with ranibizumab (Lucentis®) for branch retinal vein occlusion (BRVO).

Methods

Intravitreal injections of ranibizumab were administered in 43 eyes of 43 treatment-naïve patients with BRVO. Efficacy was assessed 1 month later. Best-corrected far/near visual acuity (BCFVA/BCNVA), MNREAD parameters (reading acuity [RA], maximum reading speed [MRS], critical print size [CPS]), CGS (CS/GS), and central macular thickness (CMT) in optical coherence tomography (OCT) before and after treatment were evaluated. The area (superior/inferior) affected by BRVO was determined by fluorescein angiography.

Results

All parameters improved significantly following treatment (p < 0.05), and all MNREAD and CGS parameters were significantly correlated with BCVA in the treated eye before and after treatment (p < 0.01). The changes in BCFVA, BCNVA, MRS, and CS were significantly correlated with the amount of change in CMT (p < 0.007; r = 0.415, 0.528, -0.465, and -0.508, respectively). MRS exhibited a percentage change that was significantly correlated with that in CMT (p < 0.007; r = -0.511). Additionally, MRS exhibited the lowest threshold CMT (397 μm) at which the most significant change in improvement was observed. CMT was less likely to improve if BRVO occurred at a superior site than if it occurred at an inferior site (0.05 < p = 0.07 < 0.1).

Conclusions

MNREAD and CGS testing were useful for evaluating BRVO treatment efficacy. MRS might be a valuable index for evaluating treatment success and making treatment decisions.

Spatial distribution of macular pigment estimated by autofluorescence imaging in elderly Japanese individuals

PURPOSE

To determine the spatial distribution types of macular pigment (MP) in elderly Japanese individuals and to consider their origin.

STUDY DESIGN

Observational case series.

METHODS

Local MP optical density (MPOD) at some eccentricities and MP volume were measured using the MPOD module of a MultiColor Spectralis in 96 pseudophakic eyes of 96 participants (age range, 52-86 years; mean age, 72.8 ± 8.3 years). The MP distribution types were determined from the MP spatial profiles. The retinal thickness (RT) at the foveal center, at both 0.5° and 0.9° eccentricities, and the foveal width were measured using optical coherence tomography.

RESULTS

The mean local MPOD at the foveal center was 0.79. Spatial distribution was classified into four types: central peak (24.0%), ring-like (40.6%), intermediate (22.9%), and central dip (12.5%). The ring-like type was the most frequent in these Japanese participants. The central-peak type showed lower MPOD than did the other types in the area outside 0.9°. The ring-like type occurred frequently in eyes with small RT at 0.5° and wider foveal width. A rough contour of the Müller cell cone was found more frequently in the central-dip type than in the other types.

CONCLUSIONS

The present characteristics of the different distribution patterns could be explained by the hypothesis that MP presents mainly in the Müller cell cone within 0.5° and in Müller cells in the outer and inner plexiform layers in the area outside 0.5°. The anatomic characteristics of Müller cells at the fovea and parafovea likely affect the MP distribution.

Grade of Cataract and Its Influence on Measurement of Macular Pigment Optical Density Using Autofluorescence Imaging

Purpose

To evaluate the influence of cataracts on measuring macular pigment optical density (MPOD) using a dual-wavelength confocal scanning autofluorescence imaging technique and to establish methods to compensate for the influence of cataracts.

Methods

This prospective case series comprised 100 eyes that underwent cataract surgery. Cataracts were graded based on the World Health Organization classification. MPOD levels were measured with the MPOD module of the Spectralis MultiColor instrument (Spectralis-MP), pre- and postoperatively. We investigated the relationship between change in MPOD values and age, cataract grade, and quality of autofluorescence images. Local MPOD levels were evaluated for four strategically chosen eccentricities within the macular region, and the total MPOD volume was evaluated within 8.98° eccentricity from the center.

Results

MPOD levels could be obtained in 67 eyes before surgery. Local and volume MPOD levels were higher postoperatively relative to preoperatively in all eyes. The mean ratio of local MPOD levels after and before surgery (correction factor, CF) ranged from 1.42 to 1.77, with larger CFs required for eccentricities closer to the foveal center. The CF for the MPOD volume was 1.31. Age, grade of nuclear cataract (NUC), posterior subcapsular opacity, and image quality index (IQI) significantly contributed to CFs. For example, regression equation for CF at 0.23° = 0.17 + 0.16 × IQI + 0.29 × NUC grade + 0.01 × age (P < 0.001).

Conclusions

Cataracts affected MPOD measurements with the Spectralis-MP, but corrected MPOD results could be obtained via regression equations.

Optic coherence tomography appearances of retinal astrocytic hamartoma and systemic features in tuberous sclerosis of Japanese patients

Purpose:

To describe the optical coherence tomography findings of retinal astrocytic hamartoma of tuberous sclerosis and to confirm the association between the type of retinal astrocytic hamartoma and systemic manifestations in Japanese patients.

Study Design:

A retrospective observational case series.

Methods:

The medical records of 35 patients with tuberous sclerosis who underwent ophthalmological examination were reviewed. The retinal astrocytic hamartomas were classified into four types based on the optical coherence tomography findings, and their association with systemic disease was evaluated.

Results:

A total of 40 retinal astrocytic hamartomas in 13 eyes of eight patients aged 4–28 years were identified. Optical coherence tomography images were obtained for 23 lesions in 10 eyes of seven patients. Retinal astrocytic hamartomas were seen as protruding lesions of varying heights (maximum thickness, range between 221 to 1043 μm). Of the 23, 15 lesions showed homogeneous reflectivity; in six lesions, hyper-reflective spots that presumably represented intratumoral calcification were noted. Vitreous changes were noted in 13 lesions; vitreous seeding by retinal astrocytic hamartoma was observed in seven eyes. There were no significant differences in the rates of each systemic feature among the optical coherence tomography types.

Conclusion:

Retinal astrocytic hamartomas were classified into four types according to the previous reports; however, this classification may be worthless because the extent of protrusion did not correspond to the intratumoral characteristics, and the involved depth of the retina was not same even in the same type. An association between the type of retinal astrocytic hamartoma and systemic manifestations was not confirmed in this small case series. We considered that the classification of retinal astrocytic hamartoma and its association with systemic manifestations need further study.

Optical Detection of Macular Pigment Formation in Premature Infants

Purpose

To demonstrate the presence of macular pigment in the retina of premature infants, and to examine its changes with age.

Methods

The participants included 40 premature infants. Infants who had received laser photocoagulation for retinopathy of prematurity were excluded. Macular pigment optical density (MPOD) was measured by fundus reflectometry using RetCam3, a digital fundus camera. The reflection imaging was performed for ROP screening. The imaging time points were from a post menstrual age (PMA) of 29 weeks 0 days to 46 weeks 5 days.

Results

The MPOD levels could be obtained from 39 premature infants. The levels at the first measurement ranged from 0 to 0.18 (mean 0.076, SD 0.044). The earliest time, when a nonvanishing MPOD level was obtained, was at a PMA of 33 weeks and 2 days, and that level was 0.05. The initial examination MPOD levels showed a moderate correlation with age (R² = 0.32, P < 0.00017). The mean MPOD levels measured each week during the follow-up period showed a very strong correlation with age (R² = 0.91, P < 0.0001). A regression line of MPOD = 0.0069 × age − 0.1783 was derived, where age is counted in PMA days.

Conclusions

The MPOD levels of premature infants were for the first time measured in living eyes. Macular pigment increased linearly with age.

Translational Relevance

Macular pigment increased with the development of macular morphology. This result suggested the importance of nutritional management of infants and mothers during perinatal period.

Reliability of a commercially available heterochromatic flicker photometer, the MPS2, for measuring the macular pigment optical density of a Japanese population

PURPOSE

The macular pigment optical density (MPOD) of a Japanese population was measured using a commercially based heterochromatic flicker photometer, the Macular Pigment Screener (MPS2). The objective of the study was to evaluate the accuracy and test-retest reliability of the MPS2 in Asian pigmented eyes.

STUDY DESIGN

Experimental study to validate the medical instrument in humans.

METHODS

Twenty-four healthy Japanese participants with no systemic or eye diseases (men: 13, women: 11; mean [SD] age 38.6 [10.9 years]) were included. The concordance of the MPOD, obtained using the MPS2 and Macular Metrics II (MM2), and the test-retest reliability were examined.

RESULTS

Determination of the MPOD was unsuccessful in 1 participant; thus, the MPOD of 23 participants was analyzed. The mean (SD) MPOD measured with the detail-mode of the MPS2 was 0.63 (0.18) and with that of the MM2, it was 0.72 (0.23). The former was significantly lower than the latter (P = .003, paired t test). The MPOD measured with the MPS2 and the MM2 showed good concordance (r = 0.79, P < .001, Pearson product moment correlation). Bland-Altman analyses showed no systematic errors between the MPS2 and the MM2. The intraclass correlation coefficient over 5 measurement times with the detail-mode of the MPS2 was 0.80, and the mean coefficient of variation was 9.4%.

CONCLUSION

The high concordance with the MM2 and good test-retest reliability found by this study suggest that the MPS2 is acceptable for use in a Japanese population. However, the mean MPOD yielded by the MPS2 was significantly lower than that yielded by the MM2. Therefore, the MPS2 and MM2 are not interchangeable in a single study.

[Anti-vascular Endothelial Growth Factor Therapy on Exudative Age-related Macular Degeneration in Routine Clinical Practice of a Single Site: the Effectiveness of Cases Followed for More than Two Years]

PURPOSE

To investigate the long-term effectiveness of as-needed anti-vascular endothelial growth factor therapy on age-related macular degeneration (AMD).

SUBJECTS AND METHODS

The number of treatments, treatment period, visual acuity and morphological changes were investigated retrospectively in 257 eyes of 248 patients (189 men and 59 women, mean age ± SD; 71.1 ± 9.2 years old) who were followed up for two years and more. Re-treatment was mainly decided based on patient's will.

RESULTS

The mean number of treatments was 6.4 3.8 in the observational period of 3.7 years. Exudative changes were resolved at least once in the observational period in 240 eyes, and 160 eyes had no exudative changes at the final visit. Type 2 neovascularization by Gass resulted in fibrotic scar more frequently than type 1. The mean decimal visual acuity was 0.36 before the initiation of treatment and 0.26 at the final visit. The treatment period was less than 100 days in 54 eyes, and multivariate analysis revealed that polypoidal choroidal vasculopathy (PCV) was a factor of prolonged treatment period. No severe adverse effects were admitted locally and systemically.

CONCLUSIONS

The deterioration of mean visual acuity was assumed to be due to the relatively small number of treatments. Twenty-one percent of all eyes preserved well without any recurrence of treatments for short periods, and PCV needed treatments for longer periods than typical AMD.

Changes in Macular Pigment Optical Density and Serum Lutein Concentration in Japanese Subjects Taking Two Different Lutein Supplements

PURPOSE

To investigate macular pigment optical density (MPOD) and serum concentration changes of lutein in Japanese subjects participating in a clinical trial in which two formulations of lutein and zeaxanthin supplements with different physiochemical properties are used.

METHODS

Thirty-six healthy volunteers were recruited into this prospective, randomized, parallel-group, double-masked comparative study at a single institute. Two products were used, FloraGLO® (Kemin Japan) and XanMax® (Katra Phytochem). The lutein particle size and zeaxanthin concentrations differed between the formulations. The subjects consumed one of the two supplements for a duration of up to 6 months. MPOD levels were measured by resonance Raman spectrometry at baseline and once a month until the end of the study. Serum lutein concentration was measured at baseline, month 3, and month 6. The subjects were also tested for contrast sensitivity, glare sensitivity, visual acuity, and in addition had a focal electroretinogram measured.

RESULTS

The mean serum lutein concentrations increased significantly after the first three months, but the mean MPOD levels in either supplement group did not show any statistically significant increase. A detailed analysis, however, revealed three response patterns in both groups for the increase of MPOD levels and serum lutein concentration, i.e. "retinal responders", who had an increase of both MPOD levels and serum lutein concentrations (n = 13), "retinal non-responders", who had only increased serum concentrations and no change in MPOD levels (n = 20), and "retinal and serum non-responders", who had neither MPOD level nor plasma concentration increases (n = 3). The subjects with low MPOD levels at baseline appeared to show increased MPOD levels at the 6 month time point upon lutein supplementation (r = -0.4090, p = 0.0133). Glare sensitivity improved in retinal responders in both supplement groups, while there were no remarkable changes in contrast sensitivity.

CONCLUSIONS

No statistically significant differences could be detected for MPOD levels and serum lutein concentrations between the two investigated lutein supplement formulations. Responses to lutein supplementation regarding MPOD levels and serum lutein concentrations varied between subjects. Subjects with lower MPOD levels at baseline responded well to lutein supplementation. However, since the number of subjects was low, a further study with more subjects is needed to prove that subjects with low MPOD levels will benefit from lutein supplementation.

TRIAL REGISTRATION

UMIN-CTR UMIN000004593.

Autofluorescence imaging of macular pigment: influence and correction of ocular media opacities

The healthy adult human retina contains in its macular region a high concentration of blue-light absorbing carotenoid compounds, known as macular pigment (MP). Consisting of the carotenoids lutein, zeaxanthin, and meso-zeaxanthin, the MP is thought to shield the vulnerable tissue layers in the retina from lightinduced damage through its function as an optical attenuator and to protect the tissue cells within its immediate vicinity through its function as a potent antioxidant. Autofluorescence imaging (AFI) is emerging as a viable optical method for MP screening of large subject populations, for tracking of MP changes over time, and for monitoring MP uptake in response to dietary supplementation. To investigate the influence of ocular media opacities on AFI-based MP measurements, in particular, the influence of lens cataracts, we conducted a clinical trial with a large subject population (93 subjects) measured before and after cataract surgery. General AFI image contrast, retinal blood vessel contrast, and presurgery lens opacity scores [Lens Opacities Classification System III (LOCS III)] were investigated as potential predictors for image degradation. These clinical results show that lens cataracts can severely degrade the achievable pixel contrasts in the AFI images, which results in nominal MP optical density levels that are artifactually reduced. While LOCS III scores and blood vessel contrast are found to be only a weak predictor for this effect, a strong correlation exists between the reduction factor and the image contrast, which can be quantified via pixel intensity histogram parameters. Choosing the base width of the histogram, the presence or absence of ocular media opacities can be determined and, if needed, the nominal MP levels can be corrected with factors depending on the strength of the opacity.

A case of retinal injury by a violet light-emitting diode

PURPOSE

To describe the first case of retinal injury by a misuse of a toy using light-emitting diode.

METHODS

A 15-year-old male Japanese student received irradiation on his right eye by a 5 mW light-emitting diode of 410 nm wavelength for 20 seconds in 2 days. He noticed decreased vision and central scotoma approximately 2 weeks later from these events. The mechanism of injury was evaluated from the estimated irradiance on the retina by comparison with experimental threshold data published.

RESULTS

Chorioretinal atrophy with visual loss and central scotoma has remained on the fovea. The patient received an estimated dose of 1.58 J/cm 2 times, which was close to the experimentally determined radiant exposure for photochemical injury of rat retina.

CONCLUSION

The violet light from light-emitting diodes is a potential hazard for the retina, and thus, direct viewing into the beam should be avoided. Children, especially, should not be allowed to play with such toys without being carefully instructed about their proper use and fully supervised.

[Morphological changes in exudative age-related macular degeneration after photodynamic therapy]

PURPOSE

Exudative age-related macular degeneration was classified into two types. Type 1 had choroidal neovascularization (CNV) below the retinal pigment epithelium (RPE) and type 1+2 had CNV extended into subretinal space. The morphological changes following photodynamic therapy were investigated for the two types.

PATIENTS AND METHODS

One hundred and five eyes of 104 patients(mean age; 70.2 +/- 8.5 (SD) years-old) were classified by clinical findings with stereoscopic fundus observation, fluorescein angiography, and optical coherent tomography. The eyes with no exudative changes after successful treatment were divided into two types: sub-pigment epithelial dry type and sub-sensory retinal dry type. In the former, the lesions remained below the RPE and in the latter, fibrous scars persisted in the subretinal space.

RESULTS

Exudation resolved in 73% of type 1 and in 67% of type 1+2 at 6 months after the initial treatment. Among eyes followed for more than one year, in 77% of type 1 and in 89% of type 1+2 the lesions became dry in a mean follow-up time of 23.9 -/+ 8.4 months with mean treatment times of 2.0 and 2.2, respectively. Type 1 improved to sub-pigment epithelial dry type, and type 1+2 to sub-sensory retinal dry type (p = 1.06 x 10(-10), chi-square test). Visual acuity of the former was better than the latter.

CONCLUSIONS

We considered that exudation was resolved with CNV remaining beneath the RPE in type 1, and fibrous scar tissue was favorably formed in type 1+2.

Comparative study of the phototoxicity of two chrolin type photosensitizers, ATX-S10(Na) and verteporfin, on vascular endothelial and retinal pigment epithelial cells

BACKGROUND AND OBJECTIVES

To compare the phototoxicity in photodynamic therapy (PDT) of ATX-S10(Na) and Verteporfin on human microvascular endothelial cells (HMVEC), vascular endothelial cells of monkey choroid and retina (CRVEC), and human retinal pigment epithelial cells (HRPE).

STUDY DESIGN/MATERIALS AND METHODS

PDT was performed in two different ways. In short dye-exposure PDT, HMVEC and CRVEC were exposed to each photosensitizer for 5 minutes followed by laser irradiation of 670 nm wavelength for ATX-S10(Na) or 689 nm for Verteporfin without washing out the photosensitizer in the medium. In long dye-exposure PDT, the cells were exposed to photosensitizers for times ranging from 5 minutes to 2 hours, washed out the photosensitizers, followed by laser irradiation in a fresh medium. PDT was performed on HRPE with PDT doses that resulted in damaging 90% of the HMVEC (ED(90)). Phototoxicity was determined by MTS Assay 1 day after PDT.

RESULTS

The degree of phototoxicity depended on the dye concentration, laser dose, and dye exposure time. In short dye-exposure PDT on HMVEC with a laser dose of 50 J/cm(2), the ED(90) was 6.3 microg/ml of ATX-S10(Na) and 0.04 microg/ml of Verteporfin, while in long dye-exposure PDT the ED(90) was 50.0 microg/ml of ATX-S10(Na) and 0.04 microg/ml of Verteporfin when the medium was supplemented with 5% fetal calf serum. The phototoxic rate on HMVEC was higher when the medium contained 5% as contrasted with 10% of serum. In short dye-exposure PDT, the ED(90) of CRVEC was 100 microg/ml of ATX-S10(Na) and an irradiance of 100 J/cm(2), and 0.08 microg/ml of Verteporfin and an irradiance of 100 J/cm(2) when the medium was supplemented with 10% serum. With some doses of short dye-exposure PDT, the ATX-S10(Na) achieved higher phototoxic rates on HMVEC and CRVEC than on the HRPE. However, long dye-exposure PDT with ATX-S10(Na) and short and long dye-exposure PDT with Vereteporfin failed to obtain higher phototoxic rates on HMVEC and CRVEC than on HRPE.

CONCLUSIONS

Verteporfin had a higher phototoxicity than ATX-S10(Na) on HMVEC and CRVEC. The CRVEC resisted more than HMVEC following PDT with both photosensitizers. In short dye-exposure PDT, ATX-S10(Na) had a more selective phototoxicity on HMVEC and CRVEC than on HRPE.

Necrotic and apoptotic cell death of human malignant melanoma cells following photodynamic therapy using an amphiphilic photosensitizer, ATX-S10(Na)

BACKGROUND AND OBJECTIVES

To investigate the phototoxic effect on and cell death modes of human malignant melanoma cells following photodynamic therapy (PDT) using ATX-S10(Na), an amphiphilic photosensitizer.

MATERIALS AND METHODS

Cultured human malignant melanoma cells were incubated in a medium containing various concentrations of ATX-S10(Na) and irradiated with a 670 nm wavelength diode laser. Phototoxicity was analyzed by a 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay, and cell death modes were investigated by fluorescence microscopy using a Hoechst 33342-propidium iodide double-staining method as well as by static gel electrophoresis. The subcellular localization of ATX-S10(Na) and mitochondrial destabilization following PDT were observed by fluorescence microscopy.

RESULTS

Higher phototoxicity was obtained with higher dye and/or laser doses. Most of the dead cells appeared apoptotic with dye and irradiation doses that induced less than 70% cytotoxicity. In contrast, most of them appeared necrotic with doses that induced 99% cytotoxicity. Cells receiving PDT showed disturbances of mitochondrial trans-membrane potential, although the primary site of ATX-S10(Na) accumulation was in lysosomes.

CONCLUSIONS

ATX-S10(Na) has a phototoxic effect on malignant melanoma cells and, therefore, potential as a photosensitizing agent for PDT designed to kill these cells. Apoptotic pathways may be activated via mitochondrial destabilization following the damage of lysosomes by PDT. Further study, including investigation of therapeutic efficacy in vivo, is warranted.

Scanning laser system for photodynamic therapy of choroidal neovascularization

BACKGROUND AND OBJECTIVES

In order to improve selectivity of photodynamic therapy (PDT) to choroidal neovascularization (CNV) associated with age-related macular degeneration, a laser scanning technique was applied to perform focal laser irradiation to the retina, and the occlusion effects of a new device to the choriocapillaris were evaluated in primate eyes.

STUDY DESIGN/MATERIALS AND METHODS

The device contains lasers for fundus observation of 785 nm and for PDT of 670 nm, matching the absorption peak of a photosensitizer, ATX-S10(Na). The laser irradiated the shape on the retina specified before treatment and shut off automatically when the predetermined treatment was achieved. The occlusion of the choriocapillaris after PDT was documented by fluorescein and indocyanine green angiography and histology.

RESULTS

The area designated for PDT was easily drawn on the touch-screen monitor, and occlusion of the choriocapillaris was achieved precisely in the area pre-selected for treatment with 5 J/cm(2) or more of radiance following administration of 8 mg/kg ATX-S10(Na).

CONCLUSIONS

This device is useful for irradiating CNV of any shape, sparing the surrounding retina. Since our previous studies suggested that selective occlusion of CNV would decrease not only the functional disturbance caused by PDT, but also the recurrence of CNV, the present device may allow more effective PDT than the slit-lamp system presently used.

PDT to monkey CNV with ATX-S10(Na): inappropriateness of early laser irradiation for selective occlusion

PURPOSE

There is controversy about which mode of laser irradiation, early irradiation with low-dose photosensitizer or late irradiation with high-dose, benefits the selective occlusion of choroidal neovascularization (CNV) in photodynamic therapy (PDT). In this study, using an amphiphilic photosensitizer, 13,17-bis (1-carboxypropionyl) carbamoylethyl-8-etheny-2-hydroxy-3-hydroxyiminoethylidene-2,7,12,18-tetraethyl porphyrin sodium (ATX-S10(Na); Photochemical Inc., Okayama, Japan), photodynamic and adverse effects of early irradiation on CNV-bearing monkey eyes were investigated.

METHODS

Experimentally induced CNV lesions and normal retina were irradiated with a diode laser (670-nm wavelength) at a dose of 1 to 90 J/cm(2) at 1 to 19 minutes after intravenous injection of 2 mg/kg body weight of ATX-S10(Na). Vascular occlusion and CNV recurrence were evaluated by fluorescein and indocyanine green angiography and histologic analysis, until 4 weeks after irradiation.

RESULTS

Of 45 different conditions, 23 did not induce CNV closure, 20 provided both CNV occlusion and retinal vessel damage, and 2 achieved selective CNV occlusion without retinal vascular injury. Recurrence of CNV was induced in 19 of 22 CNV-occluding conditions. ATX-S10(Na) angiography showed that dyes were similarly distributed between normal vessels and CNV at early time periods after injection, whereas they were preferentially accumulated in CNV after 30 minutes.

CONCLUSIONS

In PDT with ATX-S10(Na), irradiation within 20 minutes of dye injection failed to induce selective CNV occlusion, probably because there is no significant difference in the biodistribution of dye between CNV and retinal vessels. It also caused frequent CNV recurrence after extensive inflammation in the irradiated retina.

Treatment parameters for selective occlusion of experimental corneal neovascularization by photodynamic therapy using a water soluble photosensitizer, ATX-S10(Na)

Time dependent change of an accumulation of an amphiphilic photosensitizer, ATX-S10(Na) on rabbit corneal neovascularization (CoNV) was evaluated by angiography using ATX-S10(Na) as a fluorescent dye on three rabbits. The angiography showed that the dye accumulated on CoNV 3-5 hr after dye injection when the dye in the iris was minimum. The results suggested 3-5 hr after might be the optimal time to start photodynamic therapy (PDT) to occlude CoNV selectively without damage to the surrounding normal tissue such as the iris. Then the optimal treatment parameters in PDT using ATX-S10(Na) for selective occlusion of the CoNV were investigated on rabbit eyes. PDT was performed with two different time intervals between dye injection and laser irradiation of a diode laser (670 nm), different laser doses and three different dye doses on 21 animals. PDT performed immediately after dye injection selectively occluded CoNV with laser irradiations from 30.6 to 38.2 J cm(-2)and a 2 mg kg(-1)dose of ATX-S10(Na), as well as with 15.3 J cm(-2)and a 6 mg kg(-1)dose. PDT performed 4 hr after dye injection with 107.0-152.8 J cm(-2)and a 6 mg kg(-1)dose, as well as with 38.2-53.5 J cm(-2)and a 12 mg kg(-1)dose was also effective. Although PDT performed either immediately or 4 hr after ATX-S10(Na) injection selectively occluded CoNV, the width of the optimal range of radiant exposures seemed wider in PDT performed 4 hr after dye injection. It is supposed that this result is associated with the difference of dye accumulation between in CoNV and in normal tissue as shown by the present angiographical findings.

A retrospective pilot study of indocyanine green enhanced diode laser photocoagulation for subfoveal choroidal neovascularization associated with age-related macular degeneration

PURPOSE

The effectiveness and limitations of indocyanine green (ICG) enhanced diode laser photocoagulation in treating subfoveal choroidal neovascularization (CNV) associated with age-related macular degeneration (AMD) were investigated retrospectively.

METHODS

Thirty-eight eyes of 37 patients with subfoveal CNV received ICG enhanced diode laser (wavelength, 805 nm) photocoagulation in our preliminary series. Nineteen eyes had classic CNV and the others had occult CNV, which was well-delineated on ICG angiography. The rate of anatomical success and functional outcomes were investigated. Factors prognostic of a final visual acuity of 0.1 or better were analyzed. The follow-up period ranged from 6 to 51 months (mean +/- SD = 26.5 +/- 14.4 months).

RESULTS

Occlusion of CNV was achieved in 35 of 38 eyes (92%), and 7 eyes (18%) showed recurrence, which was occluded by retreatment in all but 1 eye. Ten eyes (26.3%) showed improvement of visual acuity; 16 (42.1%) showed no change; and in 12 eyes (31.6%) visual acuity deteriorated. Factors prognostic of a final visual acuity of 0.1 or better were good preoperative visual acuity (Mann-Whitney U-test, P =.0028), and a relatively short distance between the edge of laser burns and the center of the foveal avascular zone (unpaired t-test, P =.0285).

CONCLUSION

Indocyanine green enhanced photocoagulation achieved a higher anatomical success rate but functional outcomes equal to those with argon or krypton laser photocoagulation. A controlled prospective study is necessary to prove the efficacy of this treatment.

Accumulation of photosensitizer ATX-S10 (Na) in experimental corneal neovascularization

PURPOSE

To determine the most appropriate time for laser irradiation to produce selective occlusion of new corneal vessels by photodynamic therapy (PDT) with a new photosensitizer, ATX-S10(Na).

METHODS

The time course of the plasma levels of ATX-S10(Na) and the degree of dye accumulation in the corneal neovascularization after intravenous administration was determined in rabbit eyes. Plasma concentration of ATX-S10(Na) was analyzed by a spectrophotometer. The amount of ATX-S10(Na) in the new corneal vessels was measured by nitrogen-pulsed laser spectrofluorometry. Frozen sections of neovascularized cornea and iris were observed by fluorescence microscopy.

RESULTS

Plasma ATX-S10(Na) concentration was highest 5 minutes after dye injection and rapidly decreased and reached almost zero at 24 hours, indicating its prompt excretion from the body. The amount of ATX-S10(Na) in the new corneal vessels as measured by nitrogen-pulsed laser spectrofluorometry increased and reached maximal level at 2 to 4 hours. Under fluorescence microscopy, the dye was more abundantly localized in the wall of new corneal vessels than in the normal tissue at 2 to 4 hours.

CONCLUSION

These results indicate that laser irradiation between 2 and 4 hours after dye injection is appropriate for selective PDT with ATX-S10(Na) for the occlusion of new corneal vessels.

Selective occlusion of choroidal neovascularization by photodynamic therapy with a water-soluble photosensitizer, ATX-S10

BACKGROUND AND OBJECTIVE

To determine the optimal treatment parameters for selective occlusion of choroidal neovascularization (CNV) by photodynamic therapy (PDT) by using the photosensitizer ATX-S10 and a diode laser (wavelength = 670 nm).

MATERIALS AND METHODS

Experimental CNV was induced in rat fundi by argon laser photocoagulation. The distribution of ATX-S10 in the chorioretina was analyzed by fluorescence microscopy, and the optimal treatment parameters for selective occlusion of CNV were investigated by changing the dosage and timing of laser irradiation. CNV closure and resulting damage of the surrounding tissue were documented by fluorescein angiography and light and electron microscopies.

RESULTS

Fluorescence of ATX-S10 was observed to be localized in the vascular lumen of the retina and choroid within 5 min after dye injection and increased in intensity in CNV up to 2-6 h and decreased rapidly in normal tissue. Laser irradiation with radiant exposures of 7.4 J/cm2 applied immediately after dye injection or with 22.0 J/cm2 at 2-4 h later effectively occluded the induced CNV without causing significant damage to normal retinal capillaries and large choroidal vessels.

CONCLUSIONS

PDT using ATX-S10 can selectively occlude CNV. ATX-S10 is a potentially useful photosensitizer for the treatment of CNV.

Management of orbital lymphangioma using intralesional injection of OK-432

AIM

To treat orbital lymphangioma with an intralesional injection of OK-432 (group A Streptococcus pyogenes of human origin).

METHOD

A 14 year old boy had a right orbital cystic lymphangioma. The visual acuity in the eye was 20/28. In an initial treatment, 0.02 mg of OK-432, was injected into the tumour after aspiration of the fluid contents, but no effect was seen. The second treatment was performed with 0.04 mg of OK-432.

RESULT

4 months later, the lesion had totally shrunk to fibrous tissue. The side effects were fever, a local inflammatory reaction lasting 3 days, and increased intraocular pressure, which was managed by draining the fluid contents. Visual acuity improved to 20/15, and the visual field defect and restriction of eye movement seen before treatment disappeared. No recurrence was noted 1 year after treatment.

CONCLUSION

An intralesional injection of OK-432 shrunk the lymphangioma without functional disturbance and scar in the facial skin. OK-432 may be useful for orbital lymphangioma, but further studies are still warranted to determine efficacy, complications, and the optimal dose for safe treatment.

Selective photodynamic effects of the new photosensitizer ATX-S10(Na) on choroidal neovascularization in monkeys

OBJECTIVE

To determine the optimal treatment variables for photodynamic therapy (PDT) with new photosensitizer ATX-S10(Na) (13,17-bis[1-carboxypropionyl] carbamoylethyl-8-etheny-2-hydroxy-3-hydroxyiminoethyliden e-2,7,12,18-tetranethyl 6 porphyrin sodium) to induce selective occlusion of choroidal neovascularization (CNV) in nonhuman primate eyes.

METHODS

Experimental CNV was induced in monkey eyes by laser photocoagulation, and PDT was performed in neovascularized and healthy eyes with different treatment variables. At 0 to 150 minutes after 4-, 8-, and 12-mg/kg of body weight intravenous injections of ATX-S10(Na), a diode laser was irradiated at the dose of 1 to 127 J/cm2 (wavelength, 670 nm). Vascular occlusion induced by PDT was evaluated using fluorescein angiography, indocyanine green angiography, and histological examination at 1 day to 4 weeks after irradiation.

RESULTS

Selective occlusion of CNV without damage to healthy retinal and choroidal capillaries was achieved in the following conditions: 30 to 74 J/cm2 irradiation at 30 to 74 minutes after the 8-mg/kg injection, and 1 to 29 J/cm2 irradiation at 30 to 74 minutes or 30 to 74 J/cm2 irradiation at 75 to 150 minutes after the 12-mg/kg dye injection. Regrowth of CNV often occurred when the retina was heavily injured by excessive PDT.

CONCLUSION

By using optimal treatment variables, PDT using ATX-S10(Na) induces selective occlusion of CNV in nonhuman primate eyes, providing the possibility of therapeutic application to the clinical practice.

CLINICAL RELEVANCE

Occlusion of CNV without direct damage to the sensory retina is useful to preserve visual acuity in patients with exudative age-related macular degeneration. A clinical trial of PDT using ATX-S10(Na) is desirable.

A case of glaucoma with choroidal hemangioma managed by nonpenetrating trabeculectomy

BACKGROUND

Nonpenetrating trabeculectomy was used in a patient with glaucoma complicated by diffuse choroidal hemangioma.

CASE

A 12-year-old boy suffered from glaucoma with choroidal hemangioma in the left eye. Intraocular pressure was 28 mm Hg and visual acuity was 0.04. Nonpenetrating trabeculectomy was then performed.

OBSERVATIONS

Postoperative intraocular pressure was controlled at around 15 mm Hg with pilocarpine hydrochloride eye drops. Visual acuity and visual field were preserved over 19 months after the operation.

CONCLUSIONS

An increase in aqueous outflow resistance was considered to be the major mechanism in the rise in intraocular pressure, based on distinct dilatation and tortuosity of the episcleral blood vessels and congestion of Schlemm's canal. Therefore, construction of aqueous drainage by nonpenetrating trabeculectomy was effective. Retaining the trabecular meshwork was also considered effective in controlling complications such as choroidal hemorrhage and postoperative flat anterior chamber.

Long-term effectiveness of photodynamic therapy by using a hydrophilic photosensitizer ATX-S10(Na) against experimental choroidal neovascularization in rats

BACKGROUND AND OBJECTIVE

We previously demonstrated that a hydrophilic photosensitizer ATX-S10 had a potent photodynamic effect. This study was designed to reveal the long-term effectiveness of photodynamic therapy (PDT) with this agent in occluding choroidal neovascularization (CNV) and its selectivity in the neovascular tissue.

STUDY DESIGN/MATERIALS AND METHODS

Experimental CNV was induced by intense photocoagulation in rat eyes. Immediately or 2 hours after intravenous injection of 8 mg/kg body weight of ATX-S10(Na), a cis isomer of ATX-S10, eyes were irradiated by a diode laser at the radiance of 3.25-65.3 J/cm(2) Vascular occlusion was identified by fundus photography, fluorescein angiography, and histology at 1, 3, 7, 14, and 28 days after PDT. As controls, non-neovascular eyes were subjected to PDT and similarly analyzed.

RESULTS

By using the following treatment parameters, PDT with ATX-S10(Na) successfully occluded CNV without causing occlusion of retinal capillaries for 28 days; 7.4 and 19.6 J/cm(2) immediately after dye injection and 36.7 and 65.3 J/cm(2) 2 hours after injection. Although these conditions also caused occlusion of normal choriocapillaries and mild injuries of retinal vessels, retinal pigment epithelium, and photoreceptors at 1 day, retinal vessels and pigment epithelial cells recovered from damages by 28 days. No injuries were found in the inner retina.

CONCLUSION

In optimal treatment conditions, PDT with ATX-S10(Na) can induce long-term, selective occlusion of CNV without causing irreversible damages in the inner retina.

Photodynamic therapy for corneal neovascularization using topically administered ATX-S10 (Na)

BACKGROUND AND OBJECTIVE

We investigated the effect of photodynamic therapy (PDT) using topically administered ATX-S10(Na) on corneal neovascularization (CoNV).

MATERIAL AND METHODS

Rabbit eyes with induced CoNV were treated with ATX-S10(Na) eye drops (10 mg/mL) every 5 minutes, 5 to 25 times. Five to ninety minutes after topical administration, the CoNV were irradiated with a diode laser using a wavelength of 670 nm.

RESULTS

The CoNV were occluded fluorescein angiographically in 7 of 16 treated eyes. The eyes having occluded, CoNV were irradiated using fluence of 510-1019 J/cm2 within 20 minutes of eye-drop administration. However, the effect was more variable than what we found using systemic administration in our previous investigation.

CONCLUSIONS

Experimental CoNV was occluded by photodynamic therapy using topically administered ATX-S100(Na), suggesting this modality as a possible treatment for CoNV avoids the side effects found with systemic administration of the dye. Further efforts to improve the eye drops in terms of pH and osmotic pressure are needed to achieve increased dye accumulation.

Indocyanine green angiographic features prognostic of visual outcome in the natural course of patients with age related macular degeneration

AIMS

To determine indocyanine green (ICG) angiographic features prognostic of visual acuity loss in eyes following a natural course of exudative age related macular degeneration (AMD).

METHODS

89 eyes of 72 patients (48 men, 24 women) aged between 50 and 87 years old (mean 69.5 (SD 8.8) years) with classic and/or occult choroidal neovascularisation (CNV) were reviewed. ICG angiographic features were classified as follows: type 1, well demarcated hyperfluorescence with late ICG leakage; type 2, well demarcated hyperfluorescence with no late dye leakage; type 3, poorly demarcated hyperfluorescence; type 4, no hyperfluorescence. Follow up ranged from 6 to 67 months (mean 19.2 (11.5) months). Logistic regression analyses were performed using change of visual acuity (worse or not) as the dependent variable, and patient age, sex, characteristics of fluorescein angiography (classic or occult CNV), location of CNV, and each ICG type as the independent variables. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated.

RESULTS

Type 1 CNV was associated with the highest risk for visual acuity loss (OR: 7.50, CI: 1.42-39.55, p = 0.018) among the present variables. In contrast, CNV having no ICG leakage (type 2, 3, and 4), represented no significantly increased risk.

CONCLUSION

Well demarcated hyperfluorescence with late ICG leakage appears to be predictive of visual acuity loss in eyes with CNV. Thus, ICG angiography may offer a useful means of predicting visual outcomes in AMD.

[Accumulation of a photosensitizer ATX-S 10 Na (II) to experimental corneal neovascularization]

In order to determine the most appropriate time point for laser irradiation in photodynamic therapy with a new photosensitizer, ATX-S 10 Na (II), which produces selective occlusion of new vessels, we investigated the time course of plasma levels of ATX-S 10 Na (II) after intravenous administration and degree of dye accumulation in the corneal neovascularization in rabbit eyes. Plasma ATX-S 10 Na (II) concentration decreased rapidly after injection and become virtually undetectable at 24 h, indicating rapid excretion from the body. Nitrogen-pulsed laser spectrofluorometry demonstrated that the amount of ATX-S 10 Na (II) in new corneal vessels increased and reached a maximal level 2 to 4 hours after dye injection. Under a fluorescence microscope, ATX-S 10 Na (II) was localized in the wall new corneal vessels and in extravascular tissue 2 to 4 hours after dye injection. These results indicate that the appropriate time for laser irradiation in selective PDT is between 2 and 4 hours after dye injection, when a larger amount of dye is accumulated in neovasculature tissue compared to normal tissue.

Photodynamic effect of a new photosensitizer ATX-S10 on corneal neovascularization

In order to elucidate the mechanism by which a new photosensitizer ATX-S10 causes the photodynamic effect on neovasculature, we investigated the kinetics and localization of dye accumulation in the neovascular cornea of rats after systemic administration and the development of vascular injury induced by subsequent laser irradiation, compared to those in the normal iris. Under a fluorescence microscope, the neovascular cornea always exhibited more intense fluorescence than the iris between 0.5 and 4 hr after ATX-S10 administration, indicating the preferential deposit of dye in the former tissue. The fluorescence was found inside the vascular lumen at the earliest time period and thereafter in the vascular lining cells, interstitial tissue and infiltrating neutrophils until 6 hr. As observed using light and electron microscopy, laser irradiation performed 2.5 hr after ATX-S10 injection caused extensive vascular thrombosis with endothelial destruction, which persisted for at least 3 days. The proportion of thrombosed vessels at 6 hr after laser irradiation in the neovascular cornea (64+/-5%; n=3) was significantly (P<0.01) higher than that in the normal iris (44+/-8%; n=3). In the non-thrombosed vessels from heparinized rats, in which thrombosis-related ischemic effect was excluded, mitochondrial vacuolation was the pathologic change commonly seen in the endothelial cells, pericytes and neutrophils. Morphometric analysis revealed that the mitochondria of endothelial cells in the corneal new vessels were more severely injured than those in the iris vessels. The present results indicate that ATX-S10 is a potent photosensitizer which induces photodynamic occlusion particularly of new vessels probably due to the preferential biodistribution of dye in the neovascular tissue.