Cysteine Starvation Activates the Redox-Dependent Mitochondrial Permeability Transition in Retinal Pigment Epithelial Cells

PURPOSE

Glutathione (GSH) plays a key role in protection against oxidative stress. L-cysteine is thought to be rate-limiting for the synthesis of glutathione (GSH) and therefore may be a critical component in protection against oxidative stress. The purpose of this study was to investigate the role of L-cysteine in GSH metabolism and oxidative stress in human retinal pigment epithelial (hRPE) cells.

METHODS

To identify the role of cysteine in GSH metabolism in hRPE cells, a strategy of cysteine starvation was used to determine (1) GSH levels and oxidative stress by measuring reactive oxygen species (ROS) production, (2) mitochondrial membrane potential (Deltapsim) and mitochondrial ultrastructure by using conventional electron microscopy (EM), and (3) indices of cell viability and apoptosis including analysis of cells containing hypodiploid amounts of DNA.

RESULTS

Cysteine starvation resulted in approximately a 95% decrease in GSH concentrations over 24 hours. The GSH Nernst redox potential (Eh) increased approximately 70 mV (Eh=-248 +/- 2.9 mV in control cells compared with Eh=-179 +/- 2.0 mV in cysteine-starved cells) indicating significant intracellular oxidation. Cysteine starvation increased the production of ROS by mitochondrial respiratory complex III (cytochrome bc1), determined using a pharmacological strategy that resulted in the loss of Deltapsim and cell death. The loss of Deltapsim and cell death was prevented with bongkrekic acid, an inhibitor of the adenine nucleotide translocator inhibitor, suggesting activation of the mitochondrial permeability transition (MPT). This conclusion was further supported by electron microscopic studies that showed significant mitochondrial swelling, a hallmark of MPT activation. Cell death was not prevented with either the broad-spectrum caspase inhibitor zVADfmk or the caspase 3-specific inhibitor DEVD-CHO, indicating that cytochrome bc1-mediated ROS production results in the MPT and necrosis.

CONCLUSIONS

These results show that cysteine is a required component for normal GSH metabolism and protection against oxidative stress in hRPE cells.

Surgery for hemorrhagic choroidal neovascular lesions of age-related macular degeneration: ophthalmic findings: SST report no. 13

PURPOSE

To present best-corrected visual acuity (BCVA) findings and other clinical outcomes from eyes of patients enrolled in one of the Submacular Surgery Trials (SST) evaluating surgical removal versus observation of predominantly hemorrhagic subfoveal choroidal neovascularization (CNV) associated with age-related macular degeneration.

DESIGN

Randomized clinical trial (SST Group B Trial).

PARTICIPANTS

Eligible patients had subfoveal choroidal neovascular lesions greater than 3.5 disk areas (8.9 mm2) composed of at least 50% blood (either blood or CNV underlying the center of the foveal avascular zone) and BCVA of 20/100 to light perception in the study eye.

INTERVENTION

Patients were assigned randomly at time of enrollment to observation or surgical removal of blood and any associated CNV.

MAIN OUTCOME MEASURE

A successful outcome was defined a priori as either improvement in visual acuity (VA), no change in VA, or a decline in VA of no more than 1 line (7 letters) from baseline to the 24-month examination based on an intent-to-treat analysis.

RESULTS

Of 336 patients enrolled, 168 were assigned to each treatment arm; treatment arms were balanced by baseline characteristics. Of 1501 expected examinations 3 months through 36 months after baseline, 1370 (91%) were performed. Loss of > or =2 lines (> or =8 letters) of VA occurred in 56% of surgery eyes, versus 59% of observation eyes examined at 24 months. Although severe loss of VA was not the primary outcome of interest, surgery more often prevented such loss: 36% in the observation arm versus 21% in the surgery arm at the 24-month examination (chi2 P = 0.004). Of initially phakic eyes, the cumulative percentage that had undergone cataract surgery by 24 months was 44% in the surgery arm, compared with 6% in the observation arm. Twenty-seven eyes (16%) in the surgical arm, compared with 3 eyes (2%) in the observation arm, had a rhegmatogenous retinal detachment (RD).

CONCLUSIONS

Submacular surgery as performed in the SST Group B Trial did not increase the chance of stable or improved VA (the primary outcome of interest) and was associated with a high risk of rhegmatogenous RD, but did reduce the risk of severe VA loss in comparison with observation. This article contains additional online-only material available at http://www.ophsource.com/periodicals/ophtha.

Photodynamic therapy with verteporfin in ocular histoplasmosis: uncontrolled, open-label 2-year study

OBJECTIVE

To evaluate the safety, effect on visual function, and fluorescein angiographic appearance of subfoveal choroidal neovascularization (CNV) through 2 years after photodynamic therapy with verteporfin (Visudyne; Novartis AG, Basel, Switzerland) in patients with ocular histoplasmosis syndrome (OHS).

DESIGN

Open-label, 3-center, uncontrolled clinical study.

PARTICIPANTS

Ocular histoplasmosis syndrome patients with subfoveal CNV (N = 26) with a greatest linear dimension no larger than 5400 microm with classic or occult CNV extending under the geometric center of the fovea, and best-corrected visual acuity letter score of approximately 20/40 to 20/200.

METHODS

The methods were similar to those described in the 1-year results with follow-up examinations every 3 months continuing through the second year. During the second year, additional therapy was recommended if fluorescein angiography showed leakage at a scheduled visit.

MAIN OUTCOME MEASUREMENTS

Visual function measurements included the changes from baseline in visual acuity and contrast sensitivity scores. Lesion size and leakage from classic and occult CNV were assessed at month 12 and month 24. Safety assessments also were made.

RESULTS

A 24-month examination was completed in 22 of the 26 enrolled participants (85%). At the 24-month examination, median improvement from baseline in visual acuity of the 22 patients evaluated was 6 letters; median contrast sensitivity improved by 3.5 letters. At the 24-month examination, 10 patients (45%) gained 7 or more letters of visual acuity from baseline, whereas 4 patients (18%) lost 8 or more letters, including 2 patients (9%) who lost at least 15 letters. There was absence of fluorescein angiographic leakage from classic CNV in 17 of the 20 evaluable lesions (85%), and leakage from occult CNV was absent in all eyes. No serious ocular adverse events were reported, and no serious systemic event was considered to be associated with treatment.

CONCLUSIONS

Median visual acuity improved and fluorescein angiographic leakage decreased after verteporfin therapy in this small, uncontrolled clinical study of patients with subfoveal CNV resulting from OHS. Verteporfin therapy seemed to be relatively safe in these patients. The selected cases feature fluorescein angiographic examples of CNV that are important in determining when to apply verteporfin therapy.

The Gene Ontology (GO) database and informatics resource

The Gene Ontology (GO) project (http://www. geneontology.org/) provides structured, controlled vocabularies and classifications that cover several domains of molecular and cellular biology and are freely available for community use in the annotation of genes, gene products and sequences. Many model organism databases and genome annotation groups use the GO and contribute their annotation sets to the GO resource. The GO database integrates the vocabularies and contributed annotations and provides full access to this information in several formats. Members of the GO Consortium continually work collectively, involving outside experts as needed, to expand and update the GO vocabularies. The GO Web resource also provides access to extensive documentation about the GO project and links to applications that use GO data for functional analyses.

Iatrogenic open globe eye injury following sinus surgery

PURPOSE

To report a case of iatrogenic open globe eye injury occurring during endoscopic sinus surgery.

DESIGN

Case report and literature review.

METHODS

A 10-year-old boy presented with periorbital swelling and subconjunctival hemorrhage of the left eye following bilateral nasal adenoidectomy. Funduscopic examination showed evidence of a full-thickness open globe injury at the equator in the inferior nasal midperiphery.

RESULTS

The injury most likely was secondary to inadvertent perforation of the lamina papiracea with entrance into the orbit and subsequent penetration of the globe.

CONCLUSION

Sinus surgery has been reported previously in association with severe orbital complications. We are unaware of previous reports of open globe injury following sinus surgery.

Oxidation of glutathione and cysteine in human plasma associated with smoking

Cigarette smoking contributes to the development or progression of numerous chronic and age-related disease processes, but detailed mechanisms remain elusive. In the present study, we examined the redox states of the GSH/GSSG and Cys/CySS couples in plasma of smokers and nonsmokers between the ages of 44 and 85 years (n = 78 nonsmokers, n = 43 smokers). The Cys/CySS redox in smokers (-64 +/- 16 mV) was more oxidized than nonsmokers (- 76 +/- 11 mV; p <.001), with decreased Cys in smokers (9 +/- 5 microM) compared to nonsmokers (13 +/- 6 microM; p <.001). The GSH/GSSG redox was also more oxidized in smokers (-128 +/- 18 mV) than in nonsmokers (-137 +/- 17 mV; p =.01) and GSH was lower in smokers (1.8 +/- 1.3 microM) than in nonsmokers (2.4 +/- 1.0; p <.005). Although the oxidation of GSH/GSSG can be explained by the role of GSH in detoxification of reactive species in smoke, the more extensive oxidation of the Cys pool shows that smoking has additional effects on sulfur amino acid metabolism. Cys availability and Cys/CySS redox are known to affect cell proliferation, immune function, and expression of death receptor systems for apoptosis, suggesting that oxidation of Cys/CySS redox or other perturbations of cysteine metabolism may have a key role in chronic diseases associated with cigarette smoking.

Clinicopathologic findings in choroidal melanomas after failed transpupillary thermotherapy

PURPOSE

To review the clinicopathologic features of eyes enucleated after failed transpupillary thermotherapy.

DESIGN

Retrospective review.

METHODS

Pathology reports in the L.F. Montgomery Laboratory between 1998 and 2002 were searched for enucleated eyes with choroidal melanoma that had been treated only by transpupillary thermotherapy (TTT) prior to enucleation. The clinical features of the patients, including ultrasonography examination, were reviewed and compared with the pathologic findings.

RESULTS

Seven eyes from seven patients had been enucleated, representing 8% of eyes treated with TTT at our institute during the period studied. The primary indication for enucleation was tumor growth. The melanomas tended to grow laterally, with minimal if any increase in thickness. Five of the seven eyes histologically demonstrated extrascleral extension, which was detected by ultrasonography prior to enucleation in only one of those eyes.

CONCLUSIONS

Choroidal melanoma may continue to grow along a path of least resistance after TTT. The melanoma may extend laterally in the choroid and through emissary canals. Early extrascleral extension may be difficult to detect by ultrasonography.

The prognostic significance of a system for classifying mechanical injuries of the eye (globe) in open-globe injuries

PURPOSE

The aim of this study was to determine the prognostic significance of a previously published system for classifying mechanical injuries of the eye (globe) in open-globe injuries.

METHODS

The medical records of 150 patients with open-globe injuries identified from an established institutional database were retrospectively reviewed to classify all injuries at presentation by the four specific variables of the classification system: type of injury, defined by the mechanism of injury; grade of injury, defined by visual acuity in the injured eye at initial examination; pupil, defined as the presence or absence of a relative afferent pupillary defect in the injured eye; and zone of injury, defined by the location of the eye-wall opening. Final visual outcomes for these injuries were also recorded. Logistic regression models were used to analyze the data and to determine whether relationships existed between the specific classification variables and final visual acuity in the injured eyes.

RESULTS

All four classification variables were significant predictors of visual outcome. When adjusted for the other variables, grade and pupil were the most significant predictors of final visual acuity.

CONCLUSION

This system for classifying mechanical injuries of the eye appears to be prognostic for visual outcomes in open-globe injuries. In particular, the measurement of visual acuity and testing for a relative afferent pupillary defect at the initial examination should be performed in all injured eyes because of their relative prognostic significance.

Clinicopathologic study after submacular removal of choroidal neovascular membranes treated with verteporfin ocular photodynamic therapy

PURPOSE

To report the clinicopathologic findings after submacular removal of choroidal neovascular membranes (CNV) treated with verteporfin ocular photodynamic therapy.

DESIGN

Interventional case series.

METHODS

Retrospective review of eight eyes of eight patients who underwent submacular surgery for CNV after having previously received verteporfin ocular photodynamic therapy for presumed ocular histoplasmosis (one patient), age-related macular degeneration ([AMD] three patients) pathologic myopia (two patients), punctate inner choroiditis (one patient), and idiopathic CNV (one patient). All cases had undergone ocular photodynamic therapy with verteporfin using standard protocols. Six of eight patients suffered a submacular hemorrhage after ocular photodynamic therapy, and two of eight patients refused further ocular photodynamic therapy. All patients subsequently had submacular surgery with removal of the CNV. One membrane was routinely processed, sectioned, and stained with hematoxylin and eosin. Five membranes were stained with toluidine blue for light microscopic examination. Semithin (1.0 microm) sections were cut and stained with uranyl acetate-lead citrate for transmission electron microscopy.

RESULTS

Choroidal neovascular membranes were removed at 3 days (presumed ocular histoplasmosis), 29 days (punctate inner choroiditis), 63 days (AMD, pathologic myopia), 66 days (AMD), 107 days (pathologic myopia), 116 days (AMD), and 152 days (idiopathic) after verteporfin ocular photodynamic therapy. Histopathologic and ultrastructural examination showed areas of vascular occlusion at 3 days that were not seen at later time points. All specimens had patent CNV. There were signs of vascular damage with extravasated erythrocytes and fibrin, pigment clumping in cells, and inflammatory cells in all but the 3-day specimen.

CONCLUSIONS

This case series presents data only from patients who refused repeat treatment with ocular photodynamic therapy or who developed submacular hemorrhage after initial photodynamic therapy. Histopathologic evaluation of CNV 3 days after verteporfin ocular photodynamic therapy showed partial vascular occlusion that was not present in later specimens. These later specimens demonstrated evidence of vascular damage. Verteporfin ocular photodynamic therapy does not appear to lead to permanent and complete occlusion of the CNV. Thus, treatments that lead to permanent closure of CNV without damage to the retinal pigment epithelium and sensory retina are still needed.

WormBase: a cross-species database for comparative genomics

WormBase (http://www.wormbase.org/) is a web-accessible central data repository for information about Caenorhabditis elegans and related nematodes. The past two years have seen a significant expansion in the biological scope of WormBase, including the integration of large-scale, genome-wide data sets, the inclusion of genome sequence and gene predictions from related species and active literature curation. This expansion of data has also driven the development and refinement of user interfaces and operability, including a new Genome Browser, new searches and facilities for data access and the inclusion of extensive documentation. These advances have expanded WormBase beyond the obvious target audience of C. elegans researchers, to include researchers wishing to explore problems in functional and comparative genomics within the context of a powerful genetic system.

Submacular surgery trials update

Submacular surgery is a method of therapy for subfoveal CNV from multiple causes. It was first reported in the late 1980s. Since then, refinements in patient selection and surgical technique have reduced complications and made it a viable alternative to existing treatments and natural history for this condition. The Submacular Surgery Trials (SST) is a series of prospective, randomized, multicenter clinical trials designed to evaluate submacular surgery for exudative and hemorrhagic subfoveal CNV from AMD and for exudative subfoveal CNV from OHS and idiopathic causes. Recruitment has been completed for these trials, and the DSMC is continuously monitoring safety and efficacy and evaluating any modifications of study design to accommodate new therapies for subfoveal CNV.

Protection of retinal pigment epithelial cells from oxidative damage by oltipraz, a cancer chemopreventive agent

OBJECTIVE

To determine whether oltipraz (4-methyl-5-pyrazinyl-3H-1,2-dithiole-3-thione) protects against oxidative injury in cultured human retinal pigment epithelial (hRPE) cells.

METHODS

Primary cultured hRPE cells were incubated with various concentrations of oltipraz followed by treatment with the chemical oxidant tert-butylhydroperoxide (tBH). Cell viability was assessed by release of lactate dehydrogenase (LDH) and cleavage of WST-1. Intracellular and mitochondrial levels of glutathione (GSH) were measured by HPLC. Glutathione S-transferase (GST), NADPH-quinone reductase (NQR), and glutathione peroxidase (GPx) were measured by specific enzyme activity assays.

RESULTS

Treatment of hRPE cells with oltipraz inhibited tBH-induced cell death in a concentration-dependent manner with significant inhibition at 50 micro M. Olitpraz (50 micro M) increased GSH levels in hRPE cells by approximately 18% and in hRPE mitochondrial fractions by approximately 50% after 24 hours of exposure. Treatment with oltipraz increased GST and NQR activities by approximately 21% and 11%, respectively.

CONCLUSIONS

Oltipraz protects hRPE cells against tBH induced injury. The mechanism of protection is likely to include increased cellular and mitochondrial GSH levels and induction of detoxification enzymes, including GST and NQR. Dietary supplementation with oltipraz or other dithiolethiones may help protect the hRPE against oxidant induced injury.

Redox analysis of human plasma allows separation of pro-oxidant events of aging from decline in antioxidant defenses

Oxidative stress is a component of diseases and degenerative processes associated with aging. However, no means are available to assess causative oxidative events separately from decline in function of protective antioxidant systems. Previous studies show that ongoing oxidative processes maintain plasma cysteine/cystine redox at a value that is more oxidized than the antioxidant glutathione/glutathione disulfide (GSH/GSSG) system, suggesting that redox analysis of these plasma thiols could allow separate evaluation of an increase in oxidative events from a decline in antioxidant function. The present study uses measurement of cysteine/cystine and GSH/GSSG redox in plasma of 122 healthy individuals aged 19-85 years to determine whether thiol-disulfide redox changes occur with age. The results show a linear oxidation of cysteine/cystine redox state with age at a rate of 0.16 mV/year over the entire age span. In contrast, GSH/GSSG redox was not oxidized prior to 45 years and subsequently was oxidized at a nearly linear rate of 0.7 mV/year. These data suggest that there is a continuous, linear increase in oxidative events throughout adult life but that the capacity of the GSH antioxidant system is maintained until 45 years and then declines rapidly. The data further suggest that redox states of cysteine/cystine and GSH/GSSG provide an approach to clinically distinguish between increased causative oxidative events and decreased GSH antioxidant function. In principle, such analyses can be used to assess efficacy of intervention strategies against oxidative stress prior to or early after onset of clinical symptoms in aging and age-related disease.

Increased oxidant-induced apoptosis in cultured nondividing human retinal pigment epithelial cells

PURPOSE

To determine whether long-term cultured nondividing human retinal pigment epithelial (hRPE) cells are sensitive to oxidant-induced apoptosis and whether the Fas pathway is involved in the process.

METHODS

Confluent hRPE cells were maintained for 2 to 3 months in the basal medium (DMEM containing 2% fetal bovine serum) with one medium change per week. DNA synthesis was measured by incorporation of bromodeoxyuridine (BrdU) and the cell cycle was analyzed by flow cytometry. Intracellular glutathione (GSH) and glutathione disulfide (GSSG) were measured by HPLC. Apoptosis was triggered with the oxidant tert-butylhydroperoxide (tBH), recombinant soluble Fas ligand (sFasL), or agonistic anti-Fas antibody (CH-11). Cell viability was assessed by tetrazolium salt (WST-1) assay, and apoptosis was determined by measuring DNA cleavage or phosphatidylserine exposure. FasL and Fas proteins were detected by flow cytometry and Western blot. FasL and Fas transcripts were analyzed by RT-PCR.

RESULTS

After incubation in basal medium for more than 2 months, hRPE cells were largely nondividing and accumulated autofluorescent granules identified by electron microscopy to be lysosomes. Compared with proliferating hRPE cells, the nondividing cells had lower intracellular GSH, GSSG, and GSH/GSSG and a more oxidized redox potential (E(h)). Downregulation of Fas but upregulation of FasL was observed in these cells. The nondividing hRPE cells appeared more susceptible to tBH-induced apoptosis. Similar to proliferating hRPE cells, the apoptosis induced by tBH was preceded by induction of FasL, and antioxidants inhibited both FasL increase and apoptosis. Apoptosis was also inhibited with the antagonistic anti-Fas antibody ZB4. However, the nondividing hRPE cells had decreased sensitivity to apoptosis triggered by sFasL or CH-11.

CONCLUSIONS

Long-term hRPE culture created cells that were nondividing and accumulated autofluorescent granules. The increased sensitivity to tBH-induced apoptosis in these cells was associated with intracellular oxidation and upregulation of FasL. These results suggest that an increase in FasL may contribute to the vulnerability of nondividing hRPE cells to oxidant-induced apoptosis.

Photodynamic therapy of subfoveal choroidal neovascularization with verteporfin in the ocular histoplasmosis syndrome: one-year results of an uncontrolled, prospective case series

OBJECTIVE

To evaluate the safety and effect on visual acuity of photodynamic therapy with verteporfin (Visudyne, Novartis AG) in patients with subfoveal choroidal neovascularization (CNV) secondary to the ocular histoplasmosis syndrome (OHS).

DESIGN

Open-label, three-center, noncomparative prospective case series.

PARTICIPANTS

OHS patients with subfoveal CNV lesions no larger than 5400 micro m in greatest linear dimension (GLD) with classic or occult CNV extending under the geometric center of the foveal avascular zone and best-corrected visual acuity letter score of 73 to 34 (approximate Snellen equivalent 20/40-20/200).

METHODS

Twenty-six patients received verteporfin (6 mg/m(2)) infused IV over 10 minutes. Fifteen minutes after the start of infusion, a laser light at 689 nm delivered 50 J/cm(2) at an intensity of 600 mW/cm(2) over 83 seconds using a spot size with a diameter 1000 micro m larger than the GLD of the lesion. At 3-month follow-up examinations, retreatment with the same regimen was applied if angiography showed fluorescein leakage. Safety assessments were also made.

MAIN OUTCOME MEASURES

Visual function measurements were the changes from baseline in visual acuity and contrast sensitivity scores and the proportion of patients who, based on best-corrected visual acuity scores, (1) gained 7 or more letters, (2) lost 8 or more letters, and (3) lost 15 or more letters.

RESULTS

One patient was omitted from the study at the month 3 examination for not meeting the visual acuity eligibility requirements at baseline. By the month 12 examination, but excluding any retreatment at that visit, patients had received an average of 2.9 treatments of a maximum of 4 possible treatments. The month 12 median improvement from baseline in visual acuity of the remaining 25 patients was 7 letters, and median contrast sensitivity improved by 2 letters. Median visual acuity improvement was also 7 letters when three patients, who failed to meet all photographic eligibility requirements at baseline, were excluded. At the month 12 examination, 14 (56%) patients gained 7 or more letters of visual acuity from baseline, whereas 4 (16%) patients lost 8 or more letters, of which 2 (8%) lost 15 or more letters. No serious systemic or ocular adverse events were reported.

CONCLUSIONS

Median visual acuity improved after verteporfin therapy for at least 1 year in a small uncontrolled prospective case series of patients with subfoveal CNV caused by OHS. Verteporfin therapy seemed to be safe and well tolerated in these patients. Two-year data from this study will provide important, additional information on the safety and effect of verteporfin therapy for the treatment of subfoveal CNV secondary to OHS.

Macrophage and retinal pigment epithelium expression of angiogenic cytokines in choroidal neovascularization

PURPOSE

To determine the expression of angiogenic cytokines in macrophages and retinal pigment epithelium cells in choroidal neovascularization (CNV).

METHODS

Ten surgically-excised subfoveal CNV specimens and ten eye bank eyes with subfoveal CNV were routinely processed, serially sectioned, and immunostained for factor VIII (F8), CD68 (KP1), cytokeratin 18 (CK18), vascular endothelial growth factor (VEGF), tissue factor (TF), and monocyte chemotactic protein (MCP). The CNV was classified as "inflammatory active" (more inflammation than fibrosis) or "inflammatory inactive" (morefibrosis than inflammation). The immunostaining was graded as none, mild (+), moderate (++), or heavy (+++). Five additional surgically-excised CNV specimens were dual labeled with CK18/MCP or CD68/TF and confocal scanning laser microscopy was performed.

RESULTS

Vascular endothelium, macrophages, and RPE expressed F8, KP1, and CK18 respectively. Macrophages expressed + to ++ VEGF and ++ to +++ TF; RPE expressed ++ to +++ VEGF and ++ to +++ MCP. Staining for angiogenic cytokines was stronger in inflammatory active versus inflammatory inactive CNV. RPE dual labeled for CK18/MCP and macrophages dual labeled for CD68/TF.

CONCLUSIONS

This study shows that RPE cells express MCP, a cytokine involved with macrophage recruitment, and that macrophages express TF in CNV. Macrophages and RPE express VEGF, thus perpetuating angiogenesis. TF is involved with fibrin formation and provides a scaffold effect for growth of the CNV complex. CNV likely represents a dynamic process with inflammatory active and inflammatory inactive (involutional) stages.

Retinal pigment epithelial changes after macular hole surgery with indocyanine green-assisted internal limiting membrane peeling

PURPOSE

To report the results of macular hole surgery using indocyanine green to improve visualization and facilitate peeling of the internal limiting membrane.

METHODS

A retrospective noncomparative review of a consecutive series of 22 patients (22 eyes) who underwent macular hole repair using indocyanine green to facilitate visualization of the internal limiting membrane was performed. One patient was excluded because of a history of a rhegmatogenous retinal detachment. All patients underwent a three-port pars plana vitrectomy with internal limiting membrane peeling. Indocyanine green (0.1% solution) was used to assist in the visualization of the internal limiting membrane. The main outcome measures were postoperative visual acuity, macular hole status, and postoperative retinal pigment epithelial changes.

RESULTS

In 21 eyes, the median preoperative best-corrected visual acuity was 20/200 (range, 20/60 to counting fingers at 5 feet). The median postoperative visual acuity was 20/400 (range, 20/60-1/200) with an average follow-up of 13 weeks. The macular hole was closed in 18 eyes (86%) at the most recent follow-up. Ten eyes were found to have atrophic retinal pigment epithelium changes in the area of the previous macular hole.

CONCLUSIONS

Indocyanine green assists in visualization of the internal limiting membrane in macular hole surgery. In our series, 10 eyes had unusual atrophic changes in the retinal pigment epithelium at the site of the previous macular hole, or in the area where the indocyanine green solution would have had direct access to the bare retinal pigment epithelium cells. Although the use of indocyanine green improves visualization and assists with peeling of the internal limiting membrane, the safety and potential toxicity of indocyanine green to the retinal pigment epithelium require further investigation.

Indocyanine green effect on cultured human retinal pigment epithelial cells: implication for macular hole surgery

PURPOSE

To evaluate potential toxic effects of indocyanine green dye on cultured human retinal pigment epithelial cells.

METHODS

Controlled laboratory experiment. Cultured human retinal pigment epithelial cells were exposed to balanced saline solution, balanced saline solution with endoillumination, indocyanine green or indocyanine green with endoillumination. Cells were evaluated by light microscopy, electron microscopy, and a mitochondrial dehydrogenase assay.

RESULTS

Retinal pigment epithelial cells exposed to indocyanine green showed no histologic or ultrastructural changes. Those exposed to indocyanine green alone or indocyanine green plus light demonstrated a significant decrease in mitochondrial enzyme activity (P = 0.0002 and 0.005, respectively).

CONCLUSION

Brief exposure of cultured human retinal pigment epithelial cells to indocyanine green results in decreased mitochondrial enzyme activity but does not appear to influence cellular morphology or ultrastructure.