Corneal avascularity is due to soluble VEGF receptor-1.

Corneal avascularity-the absence of blood vessels in the cornea-is required for optical clarity and optimal vision, and has led to the cornea being widely used for validating pro- and anti-angiogenic therapeutic strategies for many disorders. But the molecular underpinnings of the avascular phenotype have until now remained obscure and are all the more remarkable given the presence in the cornea of vascular endothelial growth factor (VEGF)-A, a potent stimulator of angiogenesis, and the proximity of the cornea to vascularized tissues. Here we show that the cornea expresses soluble VEGF receptor-1 (sVEGFR-1; also known as sflt-1) and that suppression of this endogenous VEGF-A trap by neutralizing antibodies, RNA interference or Cre-lox-mediated gene disruption abolishes corneal avascularity in mice. The spontaneously vascularized corneas of corn1 and Pax6+/- mice and Pax6+/- patients with aniridia are deficient in sflt-1, and recombinant sflt-1 administration restores corneal avascularity in corn1 and Pax6+/- mice. Manatees, the only known creatures uniformly to have vascularized corneas, do not express sflt-1, whereas the avascular corneas of dugongs, also members of the order Sirenia, elephants, the closest extant terrestrial phylogenetic relatives of manatees, and other marine mammals (dolphins and whales) contain sflt-1, indicating that it has a crucial, evolutionarily conserved role. The recognition that sflt-1 is essential for preserving the avascular ambit of the cornea can rationally guide its use as a platform for angiogenic modulators, supports its use in treating neovascular diseases, and might provide insight into the immunological privilege of the cornea.

Failure of radiation therapy in orbital xanthogranuloma.

PURPOSE: The efficacy of radiation therapy in orbital xanthogranuloma in patients who fail medical therapy is unclear. The purpose of this study was to ascertain its effectiveness. METHODS: The records of 11 cases were reviewed retrospectively for histopathologic findings, age, gender, site of involvement, clinical manifestations, and outcomes of treatment. The case histories of the 4 patients treated with radiation, all of whom had failed medical treatment, were described. RESULTS: Of 11 patients, 5 were female, and all were white. The age range at the time of presentation was 25 to 85 years. Nine patients had bilateral involvement. Five patients, all of whom had bilateral disease, had systemic manifestations or autoimmune disease thought to be related to their orbital disease. In general, patients treated with systemic corticosteroids had at least a partial response of their lesion. However, none of the 4 patients treated with orbital radiation (3 of whom had not responded to steroid treatment and 1 of whom had responded only to high-dose steroids) experienced improvement, and at least 3 experienced exacerbation of their disease. The histologic features before treatment in all cases were similar and consistent with xanthogranuloma. CONCLUSION: Orbital xanthogranuloma may be a unilateral or bilateral condition. Particularly when bilateral, it may be associated with similar lesions elsewhere or with systemic autoimmune disorders. The results of this study suggest that fractionated radiotherapy not only may be ineffective but also may exacerbate the progression of the orbital lesions in patients who do not respond to medical therapy or who are steroid dependent on intolerable doses of medication.

Acanthamoeba sclerokeratitis.

BACKGROUND: Acanthamoeba scleritis is an uncommon but severe complication of acanthamoeba keratitis. We report the clinical and histopathologic features of a patient with acanthamoeba sclerokeratitis. METHODS: Review of the patient's clinical records and histopathologic examination of the globe including light microscopy and transmission electron microscopy. RESULTS: Review of the clinical record of the patient revealed a past ocular history of penetrating keratoplasty for persistent acanthamoeba keratitis. Later in the course of treatment, the patient developed nodular necrotizing scleritis with culture-proven viable acanthamoeba in this area. She underwent enucleation of the eye for persistent acanthamoeba sclerokeratitis. Histopathologic examination of the globe revealed no acanthamoeba cysts or trophozoites at the site of crotherapy. CONCLUSION: Our study provides evidence for the invasion of acanthamoeba organisms into the sclera in a case of acanthamoeba keratitis. The presence of trophozites in scleral tissue may exacerbate the immune response leading to nodular scleritis.

Histopathologic and trypsin digestion studies of the retina in incontinentia pigmenti.

OBJECTIVE: To report the ocular histopathologic features of a 55-year-old patient with incontinentia pigmenti retinopathy. DESIGN: Observational case report. PARTICIPANT: A 55-year-old patient with incontinentia pigmenti retinopathy. METHODS: Examination of eyes by light microscopy and retinal trypsin digestion. MAIN OUTCOME MEASURES: Clinical and histopathological findings. RESULTS: Histopathologic examination disclosed inner retinal ischemic atrophy, capillary beading, arteriolar-venous anastomoses, preretinal neovascularization, vasculopathy located at the junction of central vascular and peripheral avascular retina, retinal tears, and tractional retinoschisis. CONCLUSIONS: Patients with retinal manifestations of incontinentia pigmenti may progress to proliferative vitreoretinopathy or retinal detachment and should be observed closely over the course of their lifetime.

Electron microscopic investigation of the lens capsule and conjunctival tissues in individuals with clinically unilateral pseudoexfoliation syndrome.

PURPOSE: To determine the presence of pseudoexfoliative material in the unaffected eyes of patients with clinically unilateral pseudoexfoliation syndrome. DESIGN: Prospective observational case series. PARTICIPANTS: Thirty-two consecutive patients with clinically unilateral pseudoexfoliation syndrome, undergoing routine cataract surgery. METHODS: Transmission electron microscopy (TEM) was used to examine conjunctival and anterior lens capsule specimens in affected and unaffected eyes. MAIN OUTCOME MEASURE: Presence of characteristic pseudoexfoliation syndrome findings on TEM. RESULTS: Transmission electron microscopy demonstrated pseudoexfoliative material on either the anterior capsule or conjunctival sample from the clinically unaffected eye in 26 of the 32 patients with clinically unilateral pseudoexfoliation syndrome (81%; 95% confidence interval, 64%-93%). CONCLUSION: The results suggest that the seemingly uninvolved eye in a patient with clinically unilateral pseudoexfoliation syndrome has an 81% likelihood of being affected ultrastructurally. Several population studies examining conversion rates from unilateral to bilateral disease have found a similar proportion of patients with bilateral pseudoexfoliation syndrome in the later decades of life.

Histopathologic characteristics of choroidal melanoma in eyes enucleated after iodine 125 brachytherapy in the collaborative ocular melanoma study.

OBJECTIVE: To describe the histopathologic findings in eyes with uveal melanoma that had secondary enucleation after failed brachytherapy plaque treatment. METHODS: Histopathologic findings in eyes that had secondary enucleation after plaque radiation therapy in the Collaborative Ocular Melanoma Study (COMS) were reported on a standardized data form. The findings were compared with eyes that had primary enucleation for uveal melanoma. RESULTS: Seventy-five eyes that had secondary enucleation were studied. Compared with primary enucleations, tumors in the irradiated eyes had lower mitotic activity, a smaller proportion of histologically intact tumor, more inflammation, more fibrosis, and more vascular damage within the tumor. In addition, compared with primary enucleations, eyes previously irradiated had a higher frequency of retinal invasion by the tumor and greater damage to the retinal vasculature, consistent with radiation retinopathy; neovascularization of the iris; and vitreous hemorrhage. Tumor growth or extrascleral extension was confirmed histopathologically in 25 of 42 eyes (60%) enucleated because of a reported failure of local control. CONCLUSIONS: Eyes with secondary enucleation after brachytherapy differ histopathologically from eyes with primary enucleation for uveal melanoma. These histopathologic differences may be due to the effects of radiation, tissue conditions related to plaque failure, and, in some cases, tumor growth. In 40% of eyes enucleated because of suspected failure of local control, increased tumor size could not be histologically confirmed.

Light-scattering and ultrastructure of healed penetrating corneal wounds.

PURPOSE: To investigate quantitatively for the first time the relationship between light-scattering and ultrastructure of semitransparent scars resulting from penetrating wounds in rabbit cornea. METHODS: Penetrating wounds, 2 mm in diameter, were made in the central cornea and allowed to heal for 3.6 to 4.5 years at which time the rabbits were killed. The scar and cornea thickness outside the scar were measured using ultrasonic pachymetry. Corneas were excised immediately and their transmissivity was measured from 400 to 700 nm. The tissue was then prepared for transmission electron microscopy. Transmission electron micrographs (TEMs) were analyzed to determine fibril positions and radii. Scattering was calculated using the direct summation of fields (DSF) METHOD: RESULTS: Scar thickness averaged 0.26 +/- 0.04 mm, and the scars were flat. Thickness outside the scars averaged 0.40 +/- 0.04 mm. Three scars were moderately transparent, five were less transparent, and one was much less transparent. The wavelength dependence of the measured total scattering cross- section was indicative of the presence of voids (lakes) in the collagen fibril distribution, and lakes were evident in the TEMs. The images showed enlarged fibrils and some showed bimodal distributions of fibril diameters. Calculated scattering was characteristic of that expected from regions containing lakes-a finding consistent with the scattering measurements. CONCLUSIONS: Despite the long healing time, these scars remained highly scattering. A combination of lakes, disordered fibril distributions, and a significant population of enlarged fibrils can explain the scattering. A possible cellular contribution cannot be ruled out.

Ocular clusterin expression in von Hippel-Lindau disease.

PURPOSE: Clusterin is a multifunctional glycoprotein. Its mRNA is ubiquitously expressed, with high levels in von Hippel-Lindau (VHL) target organs such as the brain, liver, kidney, and adrenal medulla. Decreased clusterin secretion has been reported in renal cell carcinoma associated with VHL disease. The purpose of this study was to investigate ocular clusterin expression in VHL disease. METHODS: This retrospective case series included nine eyes with retinal hemangioblastoma/hemangioma associated with VHL disease, one eye from a patient with a history of VHL disease and central nervous system hemangioblastomas but without ocular lesions, one surgically-excised optic nerve with optic nerve hemangioblastoma/hemangioma, and three normal control eyes. Ocular specimens were evaluated by routine histology, immunohistochemistry for clusterin expression, and molecular detection of clusterin transcripts within ocular VHL hemangioblastomas compared with normal tissue from the same eye using microdissection and quantitative real-time PCR. RESULTS: All retinal hemangioblastoma were composed of typical VHL tumor cells admixed with small vascular channels as well as glial cells. Marked decrease of clusterin immunoreactivity was detected in all retinal hemangioblastoma and the optic nerve hemangioblastoma, whereas positive clusterin reactivity of the vascular and glial components was similar to that of normal retina. Quantitative real-time PCR analysis confirmed the decrease of clusterin mRNA in the VHL associated retinal hemangioblastoma and optic nerve hemangioblastoma in five cases. CONCLUSIONS: Clusterin shows possible important functions in tumor suppression by the VHL gene product (pVHL) and the potential to be a novel biomarker in retinal hemangioblastoma associated VHL disease. Further investigation of clusterin may provide better understanding of retinal hemangioblastoma associated with VHL disease.

Ocular autopsy and histopathologic features of child abuse.

PURPOSE: To study the ocular histopathologic features in eyes of children with fatal suspected child abuse. DESIGN: Retrospective case series. PARTICIPANTS: One hundred eighteen autopsy cases of known or suspected child abuse. METHODS: The ocular autopsy and histopathologic features of a cohort of consecutive cases of known or presumed child abuse submitted by Maryland's Office of the Chief Medical Examiner or Johns Hopkins Hospital to the Wilmer Eye Pathology Laboratory were tabulated. MAIN OUTCOME MEASURE: Ocular hemorrhage or structural abnormality. RESULTS: Retinal hemorrhage was present in 44% of cases. Circumferential folds with macular schisis cavities were present in 23% of cases and were bilateral in half of those cases. Peripapillary scleral hemorrhage was present in 38% of cases, and subdural hemorrhage was present in the distal optic nerve in 46% of cases. Hemosiderin was present in 27% of cases. CONCLUSIONS: Intraretinal hemorrhages, circumferential macular folds with schisis cavities, peripapillary scleral hemorrhages, and subdural hemorrhages are common pathologic findings in cases of fatal known or suspected child abuse. Their presence on autopsy should raise the suspicion of shaking or blunt nonaccidental trauma.

Floretlike cells in in situ and prolapsed orbital fat.

PURPOSE: Orbital pleomorphic lipoma has been rarely reported in the literature. Although floretlike cells are characteristic of pleomorphic lipoma, they are not pathognomonic. We reviewed cases of prolapsed orbital fat and exenteration specimens to determine the significance of presence of these cells in the diagnosis of orbital pleomorphic lipoma. DESIGN: Retrospective interventional case series with clinicopathologic correlation. PARTICIPANTS: Seventy-two specimens of 45 patients with prolapsed orbital fat and 74 exenteration specimens as controls. INTERVENTION: Histologic review of the specimens including light microscopy, Masson trichrome staining, immunostaining for S100, CD34, CD68, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay, and transmission electron microscopy and review of clinical records and analysis of the data with generalized estimation equation. MAIN OUTCOME MEASURE: Evidence of histologic abnormalities in histologic specimens and clinical and demographic data. RESULTS: Floretlike cells were present in 31 of 72 (43%) specimens of prolapsed orbital fat and in 12 of 74 (16%) orbital exenterations. Fewer than 6 florets were present in twenty 40x high-power fields in 15 (48%), 6 to 10 in 9 (29%), and >10 in 7 (23%) specimens. The florets stained positive for CD34 but not for S100 or CD68. TUNEL assay revealed significant nuclear pyknosis, and transmission electron microscopy disclosed spindle-shaped cells with abundant rough endoplasmic reticulum and no basement membrane. The mean age of patients with prolapsed orbital fat with florets was 67 years (range, 52-86). Of 31 samples, 29 (94%) were from males. Of 30 samples, 29 (97%) were located in the superotemporal conjunctiva; only one was located in the lower lid. There was significant association between the presence of florets and location of the prolapsed orbital fat (P = 0.0013) and gender (P = 0.0015). CONCLUSION: Floretlike cells may be present in in situ and prolapsed orbital fat as a degenerative process. What some have called "orbital pleomorphic lipoma" is in fact only age-related orbital fat prolapse.

Subluxation of suture-fixated posterior chamber intraocular lenses a clinicopathologic study.

PURPOSE: To report the occurrence of subluxation of suture-fixated posterior chamber (PC) intraocular lenses (IOL) and elucidate the mechanisms involved. DESIGN: Prospective clinicopathologic study. PARTICIPANTS: A single 10-0 Prolene suture explanted from a patient who experienced subluxation of his PC-IOL, 11.5 years after placement. Furthermore, multiple 10-0 Prolene sutures and PC-IOLs used for iris fixation were studied as controls. METHODS: Scanning electron microscopy (SEM) was used to analyze the surface of the explanted suture. In addition, randomly selected 10-0 Prolene sutures cut with Vannas scissors and cut with the positioning holes of a randomly selected PC-IOL identical to that implanted in the patient's eye were examined as controls. Finally, the positioning holes of several randomly selected, iris-fixated PC-IOLs were studied using SEM with particular attention to surface quality and edge finish. MAIN OUTCOME MEASURES: Presence of any signs of suture degradation, the character of the cut edge of the suture, as well as the characteristics of the positioning holes of the PC-IOLs. RESULTS: Scanning electron microscopy of the explanted suture revealed sharply cut edges, without significant degradation of the suture, and no intact loop. Scanning electron microscopy of the control suture cut with a PC-IOL demonstrated a similarly cut edge. The positioning holes of the examined PC-IOLs had a sharp edge, and some also had an imperfect finish. CONCLUSION: We conclude that the surface properties of the positioning holes lead to cutting of the suture, and subsequent subluxation of the PC-IOL.

Advanced glycation end products and receptors in Fuchs' dystrophy corneas undergoing Descemet's stripping with endothelial keratoplasty.

PURPOSE: To describe the histopathologic features of Descemet's membrane (DM) obtained from Fuchs' endothelial corneal dystrophy (FECD) corneas undergoing Descemet's stripping with endothelial keratoplasty (DSEK) and to assess the presence of advanced glycation end products (AGEs) and their receptors in FECD endothelium and DM. DESIGN: Prospective observational case series. PARTICIPANTS: Five eyes of 5 patients undergoing DSEK for FECD and 4 normal control eyebank corneas. METHODS: Descemet's membrane and corneal endothelium from FECD patients undergoing DSEK were assessed with hematoxylin-eosin staining and immunohistochemistry for AGEs, receptor of AGEs (RAGE), and galectin 3 (AGE-R3). MAIN OUTCOME MEASURES: Histopathologic abnormalities and presence of AGEs, RAGE, and AGE-R3 in DSEK specimens. RESULTS: Histopathologic assessment of DSEK specimens from FECD patients disclosed thickening and nodularity of DM and loss of endothelial cells. Immunohistochemical staining of FECD DM for AGE, RAGE, and AGE-R3 showed an abundance of AGEs in the anterior portion of DM, mild positivity for RAGE, and moderate positivity for AGE-R3. CONCLUSIONS: Tissue quality after DSEK is sufficient to allow detailed histopathologic analysis. The presence of AGEs, RAGE, and AGE-R3 in DM and corneal endothelium of FECD patients supports a link between accumulation of AGEs, oxidative stress, and corneal endothelial cell apoptosis in the pathogenesis of FECD.

Histopathologic and immunologic aspects of alphacor artificial corneal failure.

PURPOSE: To describe the histopathologic and immunologic characteristics of late artificial corneal failure in a small series of patients who underwent AlphaCor implantation and to elucidate the mechanisms involved. DESIGN: Clinicopathologic case series. METHODS: Three patients were diagnosed with corneal melting during the late postoperative period and required the removal of the devices. The explanted devices embedded within the corneal tissues were examined by light microscopy, electron microscopy, and immunohistochemical studies. RESULTS: Light microscopic examination of the specimens disclosed adequate biointegration with no foreign body response. Immunofluorescence studies of the skirt exhibited expression of inflammatory cytokines such as interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha), and some interferon gamma (IFN-gamma). The keratocytes stained positively for Thy-1 and smooth muscle actin but negatively for CD34. CONCLUSIONS: Although these findings confirm the occurrence of biointegration, myofibroblastic differentiation of the ingrowing keratocytes is a prominent feature.

Asymptomatic conjunctival mucosa-associated lymphoid tissue-type lymphoma with presumed intraocular involvement.

PURPOSE: To report a case of conjunctival mucosa-associated lymphoid tissue (MALT) lymphoma with presumed intraocular involvement. METHODS: Observational case report. RESULTS: A 73-year-old white man presented for a routine eye examination and was found to have a salmon-colored bulbar conjunctival mass of the left eye. Ultrasound showed a low-reflective mass with diffuse thickening of the ciliary body and choroid. Immunohistochemistry and flow cytometry of an incisional biopsy specimen suggested a polyclonal lesion. Treatment with topical steroids yielded no clinical improvement, and excisional biopsy was performed. A diagnosis of MALT lymphoma was made after polymerase chain reaction (PCR) analysis of the immunoglobulin heavy chain (IgH) locus revealed a clonal B-cell population. CONCLUSIONS: Conjunctival MALT lymphoma can present without symptoms and can extend intraocularly. PCR analysis of the IgH locus can identify lesion clonality when immunohistochemistry and flow cytometry fail to do so.

Corneal endothelial injury thresholds for exposures to 1.54 micro m radiation.

The endothelial injury threshold was determined in rabbit for an 11-s exposure to 1.54 micro m radiation from an Erbium fiber laser. The beam was Gaussian with a 1/e diameter of 7 mm. Cell damage was detected with a wet staining technique. The threshold dose for these conditions is 4.4 x 10(5) J m(-2) (44 J cm) and is only 9% greater than the threshold for epithelial damage for the same exposure conditions. Exposures just above the threshold caused substantial endothelial damage, including loss of cells. The calculated endothelial temperature increase at the threshold is similar to that calculated for the epithelium at its injury threshold for the same exposure conditions. The results suggest that endothelial damage can be correlated with a critical temperature damage model with a critical temperature increase near 40 degrees C. The results also suggest that if a person were to receive an exposure only slightly above the epithelial injury threshold from a beam having a diameter of 7 mm (which is the diameter of the exit pupil of 7 x 50 binoculars) he or she would risk sustaining substantial endothelial damage.

Urate deposition in the iris and anterior chamber.

OBJECTIVE: To report on a patient with clear gelatinoid deposits on the iris and in the anterior chamber (AC). DESIGN: Observational case report. METHODS: Examination of AC aspirate and iris and conjunctival biopsies by light and transmission electron microscopy. MAIN OUTCOME MEASURES: Clinical and histopathological findings. RESULTS: Analysis of the aqueous humor and iris ultrastructure disclosed the presence of urate deposits. CONCLUSIONS: Urate deposition in the iris and anterior chamber rarely occurs.

Role of electron microscopy in the diagnosis of ocular mucous membrane pemphigoid.

PURPOSE: To evaluate the role of electron microscopy (EM) for the diagnosis of ocular mucous membrane pemphigoid (MMP) among patients with cicatrizing conjunctivitis. DESIGN: Retrospective case series. PARTICIPANTS: One hundred twenty-eight patients with cicatrizing conjunctivitis referred for the evaluation of possible ocular MMP between January 1985 and February 2002 who underwent conjunctival biopsy and evaluation with EM and direct immunofluorescent (DIF) techniques. METHODS: The diagnosis of each patient was based on DIF techniques. The reproducibility of EM readings was measured by assessing intraobserver and interobserver variability. The diagnosis from EM was compared to the DIF diagnosis from the same patient to evaluate the validity of the EM diagnosis. MAIN OUTCOME MEASURES: Sensitivity, specificity, positive predictive value, and negative predictive value of EM for diagnosing ocular MMP. RESULTS: One hundred twenty-six of 128 conjunctival biopsies were available for evaluation of EM findings. The percent agreement between 2 readings from the same observer was 92%, and the percent agreement between 2 independent observers was 78%. The sensitivity and specificity of EM for the diagnosis of ocular MMP were 51% and 72%, respectively. The positive predictive value of EM for the diagnosis of ocular MMP was 49%. CONCLUSIONS: The reproducibility of EM findings was good as indicated by high percent agreement for both intraobserver and interobserver measurements. However, the sensitivity, specificity, and positive predictive value of EM for the diagnosis of ocular MMP was low. It seems that EM has limited usefulness in the diagnosis of ocular MMP.

The macular hole: histopathologic studies.

OBJECTIVE: To delineate the light and electron microscopic features of tissue removed at the time of macular hole surgery. METHODS: The ocular fluid specimens were concentrated using Millipore filters and stained with a modified Papanicolaou and the periodic acid-Schiff stains in 697 cases. In 92 cases, surgically isolated tissue was processed and examined by electron microscopy. RESULTS: The findings in the specimens studied by the Millipore filter technique included vitreous strands; cellular fragments in 108 cases (13.3%); fibrocellular fragments in 75 (9.2%); and fragments of internal limiting lamina (ILL) of the retina in 104 (12.8%). Findings in the 92 specimens with tissue studied by electron microscopy included native vitreous collagen in 48 cases (52.2%); new collagen in 6 (6.5%); native and new collagen in 1 (1.2%); ILL of the retina in 54 (58.7%); and a variety of cells in 22.5% of cases, including fibrocytes, myofibrocytes, fibrous astrocytes with and without myoblastic features, Mueller cells, retinal pigment epithelium with and without myoblastic features, and inflammatory cells. The organization of the tissue elements included a cellular layer along one surface of a layer of cortical vitreous in 18 cases, cortical vitreous along the inner surface of the ILL of the retina in 10, and cortical vitreous sandwiched between the ILL of the retina and a layer of cells in 9. CONCLUSIONS: Tangential traction induced by fluid movements affecting the cortical vitreous is a major factor in the pathogenesis of idiopathic macular holes. Cellular proliferation is a secondary change seen in 22.2% of cases.

An apolipoprotein E variant may protect against age-related macular degeneration through cytokine regulation.

Age-related macular degeneration (AMD) is the leading cause of visual impairment and blindness among the elderly in Western countries. Genetic factors, age, cigarette smoking, nutrition, and exposure to light have been identified as AMD risk factors. In this study, we investigated the association between ApoE C112R/R158C single nucleotide polymorphisms (which determine the E2, E3, and E4 isoforms) and age-related macular degeneration (AMD), and the mechanism underlying the association. Genomic DNA was extracted from 133 clinically screened controls, 94 volunteers with a younger mean age, 120 patients with advanced AMD, and 40 archived ocular AMD slides for single nucleotide polymorphism typing. The effects of recombinant ApoE isoforms on CCL2 (a chemokine), CX3CR1 (a chemokine receptor), and VEGF (a cytokine) expression in cultured human retinal pigment epithelium (RPE) cells were tested and serum cholesterol profiles of the clinically screened subjects were analyzed. ApoE112R (E4) distribution differed significantly between AMD patients and controls. ApoE112R allele frequency was 10.9% in the AMD group when compared with 16.5% in the younger controls and 18.8% in the clinically screened controls. The pathologically diagnosed archived AMD cases had the lowest allele frequency of 5%. No significant differences in ApoE158C (E2) distribution were observed among the groups. A meta-analysis of 8 cohorts including 4,289 subjects showed a strong association between AMD and 112R, but not 158C. In vitro studies found that recombinant ApoE suppresses CCL2 and VEGF expression in RPE cells. However, the E4 isoform showed more suppression than E3 in both cases. These results further confirm the association between ApoE112R and a decreased risk of AMD development. The underlying mechanisms may involve differential regulation of both CCL2 and VEGF by the ApoE isoforms.