Aphakic cystoid macular edema. The pharmacology of ocular trauma

Ultra-Widefield Fluorescein Angiography Findings in Patients with Macular Edema Following Cataract Surgery

Purpose: To evaluate the ultra-widefield fluorescein angiography (UWFA) findings in patients with macular edema (ME) following cataract surgery.Methods: Thirty-three eyes from patients who showed greater than a 30% increase in the central subfield thickness following cataract surgery were included. UWFA scored according to a system suggested by the Angiography Scoring for Uveitis Working Group (ASUWG). Factors associated with a high ASUWG score were evaluated.Results: Thirty-three (100.0%) of the 33 eyes showed abnormal UWFA findings, including optic disc staining (81.8%), capillary leakage (100.0%), pinpoint leakage (84.8%), peripheral retinal vascular leakage (24.2%) and retinal staining (6.1%). Multiple regression analysis reveals that following adjustment for other factors, younger age was independently associated with a higher ASUWG score (R² = 0.476, p = .001).Conclusions: Patients with ME following cataract surgery show generalized inner and outer blood-retinal barrier breakage. Particular attention is required during cataract surgery in young patients.

Anti-angiogenic Therapy for Retinal Disease

Recent breakthroughs in our understanding of the molecular pathophysiology of retinal vascular disease have allowed us to specifically target pathological angiogenesis while minimizing damage to the neurosensory retina. This is perhaps best exemplified by the development of therapies targeting the potent angiogenic growth factor and vascular permeability mediator, vascular endothelial growth factor (VEGF). Anti-VEGF therapies, initially introduced for the treatment of choroidal neovascularization in patients with age-related macular degeneration, have also had a dramatic impact on the management of retinal vascular disease and are currently an indispensable component for the treatment of macular edema in patients with diabetic eye disease and retinal vein occlusions. Emerging evidence supports expanding the use of therapies targeting VEGF for the treatment of retinal neovascularization in patients with diabetic retinopathy and retinopathy of prematurity. However, VEGF is among a growing list of angiogenic and vascular hyperpermeability factors that promote retinal vascular disease. Many of these mediators are expressed in response to stabilization of a single family of transcription factors, the hypoxia-inducible factors (HIFs), that regulate the expression of these angiogenic stimulators. Here we review the basic principles driving pathological angiogenesis and discuss the current state of retinal anti-angiogenic pharmacotherapy as well as future directions.

A comparative study of postoperative intraocular pressure changes in small incision vs conventional extracapsular cataract surgery

AIMS

To compare short- and long-term IOP changes in small incision cataract surgery (SICS) vs conventional extracapsular cataract surgery (CECS).

METHODS

A total of 232 eyes of as many patients undergoing cataract surgery were randomized to SICS or CECS. Sixteen eyes had to be excluded out of the study. IOP was recorded preoperatively and postoperatively on day 1, 2, and 7; and then after 1, 3, and 6 months. Only 160 eyes remained under 6-month follow-up, out of which 48 had CECS and remaining 112, SICS. Results were analysed statistically (repeated measure ANOVA, multiple comparisons).

RESULTS

A significantly higher IOP was observed on day 1, 2, and 7 in both types of surgeries as compared to mean preoperative IOP. Variation in rise was more pronounced in CECS (nearly twofold) than in SICS (P<0.05). Maximum decrease in IOP occurred during the first week and it was more rapid in SICS than CECS. At 3 months, IOP was significantly higher than baseline in CECS but significantly lower in SICS. From 3 to 6 months, there was no further decrease in IOP in either type of surgery.

CONCLUSIONS

IOP rises significantly on day one in CECS and SICS and thereafter comes down slightly by day 2 and rapidly by day 7. IOP rise is more pronounced in CECS than in SICS. After 1 week to 3 months, IOP decline is very gradual and thereafter ceases to decrease.

Control of inflammation and prophylaxis of endophthalmitis after cataract surgery: a multicenter study

PURPOSE

To compare two different postcataract surgery antibiotic/steroid therapeutic combinations, for clinical results as well as patient satisfaction.

METHODS

Prospective randomized clinical trial of patients with bilateral operative cataract. Postoperatively, for 15 days one eye was randomly assigned to therapy with the combination chloramphenicol 0.25%-betamethasone 0.13% gel three times a day (Group 1) and the other to the combination tobramycin 0.3%-dexamethasone 0.1% eyedrops four times a day (Group 2).

RESULTS

A total of 142 patients (284 eyes) completed the study. The authors could not detect any significant difference between Group 1 and Group 2 concerning preoperative evaluation, surgical procedure, and complications. Pertaining to the two therapeutic regimens, efficacy, side effects, and clinical findings such as uncorrected visual acuity, intraocular pressure, edema or hyperemia of eyelids and/or conjunctiva, conjunctival and/or ciliary vessels congestion, decreased corneal transparency, corneal edema, Descemet folds, anterior chamber Tyndall and depth, and posterior synechiae were also comparable. Postoperative subjective pain and dry eye sensation were comparable between the two groups, while the gel preparation elicited a significantly more pleasant sensation in the patients (p=0.04).

CONCLUSIONS

The motivation for use of a gel is to prolong the permanence of associated drugs on the ocular surface, increasing potency and decreasing concentration of the drug and rate of administration. This in order to improve compliance and decrease potential side effects. Chloramphenicol 0.25%-betamethasone 0.13% gel combination proved to have comparable efficacy, tolerance, and better acceptance by the patients than an aqueous tobramycin 0.3%-dexamethasone 0.1% preparation.

Hypopyon uveitis following band keratopathy removal in ankylosing spondylitis-a case report

PURPOSE

To report an interesting case of hypopyon uveitis following successive band keratopathy removal in both the eyes in a patient with ankylosing spondylitis.

DESIGN

Retrospective case report.

RESULTS

A 70-year-old Indian male with ankylosing spondylitis and a 40-year history of chronic anterior uveitis underwent band keratopathy removal (EDTA chelation) in both eyes at an interval of six months. On both occasions, he developed a severe hypopyon uveitis on the first postoperative day, which was successfully treated with topical and oral steroids.

CONCLUSION

Any ocular procedure, even as trivial as band keratopathy removal, can elicit a severe uveitis in a chronically inflamed eye. The probable mechanisms are discussed.

Inflammation-mediated retinal edema in the rabbit is inhibited by topical nepafenac

The purpose of this study was to evaluate the ability of the nonsteroidal anti-inflammatory drug nepafenac to prevent development of mitogen-induced pan-retinal edema following topical ocular application in the rabbit. Anesthetized Dutch Belted rabbits were injected intravitreally (30 microg/20 microL) with the mitogen concanavalin A to induce posterior segment inflammation and thickening (edema) of the retina. The Heidelberg Retina Tomograph was used to generate edema maps using custom software. Blood-retinal barrier breakdown was assessed by determining the protein concentration in vitreous humor, whereas analysis of PGE2 in vitreous humor was performed by radioimmunoassay. Inhibition of concanavalin A-induced retinal edema was assessed 72 h after initiation of topical treatment with nepafenac (0.1-1.0%, w/v), dexamethasone (0.1%), VOLTAREN (0.1%), or ACULAR (0.5%). Concanavalin A elicited marked increases in vitreal protein and PGE2 synthesis at 72 h postinjection. Retinal thickness was also increased by 32%, concomitant with the inflammatory response. Topical application of 0.5% nepafenac produced 65% reduction in retinal edema which was correlated with 62% inhibition of blood-retinal barrier breakdown. In a subsequent study, 0.5% nepafenac significantly inhibited (46%) blood-retinal barrier breakdown concomitant with near total suppression of PGE2 synthesis (96%). Neither Voltaren nor Acular inhibited accumulation of these markers of inflammation in the vitreous when tested in parallel. This study demonstrates that nepafenac exhibits superior pharmacodynamic properties in the posterior segment following topical ocular dosing, suggesting a unique therapeutic potential for a variety of conditions associated with retinal edema.

Cellular mechanisms of blood-retinal barrier dysfunction in macular edema

PURPOSE

To determine the mechanism of blood-retinal barrier (BRB) dysfunction in human and experimental specimens using immunocytochemistry.

METHODS

Extravascular albumin was localized in clinical specimens and retinas from transgenic mice that overexpress vascular endothelial growth factor (VEGF) in the photoreceptors. Transgenic mouse retinas were also labeled with Griffonia simplicifolia isolectin-B4 (GSA), a lectin that binds to endothelial cells.

RESULTS

The BRB is established by the presence of tight junctions between the retinal vascular endothelial (RVE) cells and the RPE cells and by a paucity of intraendothelial cell vesicles. When BRB breakdown occurs in human ocular disorders such as diabetic retinopathy, retinitis pigmentosa, or cystoid macular edema, staining for extravascular albumin reveals leakage through the tight junctions, an upregulation of intraendothelial vesicles, and permeation of RVE or RPE cells that have undergone degenerative changes. VEGF, in addition to inducing neovascularization (NV), promotes vascular leakage. In VEGF transgenic mice, BRB failure is confined to the outer retina, the area where NV occurs. GSA binds to the luminal and abluminal surfaces of RVE cells in new and established vessels and to intraendothelial vesicles and interendothelial cell junctions in areas of vascular leakage.

CONCLUSION

BRB dysfunction may be mediated by leakage through the tight junctions of RVE or RPE cells, by trans-endothelial vesicular transport, or by permeation of RVE or RPE cells that have undergone degenerative changes. GSA may be a useful marker to assist in recognizing open tight junctions and an increase in intraendothelial cell vesicles, which are indicative of BRB failure.

Medical prophylaxis and treatment of cystoid macular edema after cataract surgery. The results of a meta-analysis

OBJECTIVE

The study aimed to determine the effectiveness of prophylactic medical intervention in reducing the incidence of cystoid macular edema (CME) and the effectiveness of medical treatment for chronic CME after cataract surgery.

DESIGN

The study design was a systematic review and meta-analysis of published reports of randomized clinical trials (RCTs).

PARTICIPANTS

Sixteen RCTs involving 2898 eyes examining the effectiveness of medical prophylaxis of CME and 4 RCTs involving 187 eyes testing the effectiveness of medical treatment of chronic CME were used in the study.

INTERVENTIONS

Medical prophylaxis of treatment (cyclo-oxygenase inhibitors or corticosteroids) versus control (placebo or active treatment) was performed.

MAIN OUTCOME MEASURES

Incidence of angiographically diagnosed CME, incidence of clinically significant CME, and vision were measured.

RESULTS

Thirty-six articles reported testing a prophylactic medical intervention for CME after cataract surgery. The incidence of CME varied extensively across studies and was related to the study design used. Summary odds ratios (OR) indicated that prophylactic intervention was effective in reducing the incidence of both angiographic CME (OR = 0.36; 95% confidence interval [CI] = 0.28-0.45) and clinically relevant CME (OR = 0.49; 95% CI = 0.33-0.73). There also was a statistically significant positive effect on improving vision (OR = 1.97; 95% CI = 1.14-3.41). A combination of the results of the four RCTs testing medical therapy for chronic CME indicated a treatment benefit in terms of improving final visual acuity by two or more Snellen lines (OR = 2.67; 95% CI = 1.35-5.30). Assessment of the quality of the 20 RCTs included in the meta-analyses indicated problems in the design, execution, and reporting of a number of trials.

CONCLUSION

A combination of the results from RCTs indicates that medical prophylaxis for aphakic and pseudophakic CME and medical treatment for chronic CME are beneficial. Because most of the RCTs performed to date have problems related to quality, a well-designed RCT is needed to confirm this result, using clinical CME and vision as outcomes.

Immunohistochemical localization of blood-retinal barrier breakdown sites associated with post-surgical macular oedema

Post-surgical macular oedema results from blood-retinal barrier breakdown, but it is not accompanied by structural abnormalities in the retinal vessels or retinal pigmented epithelium. Previous studies, using horseradish peroxidase in a primate model, suggested that leakage occurs primarily through this epithelium. This study was conducted to localize sites of the barrier breakdown in humans following different types of intra-ocular surgery and to compare them with eyes affected with ocular inflammatory disease, ocular infection, and choroidal melanoma. Paraffin sections of eyes were immunohistochemically stained for albumin to localize extravascular albumin, which was graded in a masked study. With aphakia/pseudophakia, penetrating keratoplasty, ocular inflammatory disease, ocular infection, and choroidal melanoma, barrier breakdown occurred primarily at the inner blood-retinal barrier (retinal vasculature), but leakage also occurred at the outer barrier (retinal pigmented epithelium). After retinal re-attachment surgery, the inner and outer blood-retinal barriers were equally compromised. Vascular leakage in the optic nerve head coincided with barrier failure in these disorders. The widespread pattern of blood-retinal barrier compromise with leakage at multiple sites suggests that soluble mediators are likely to play a role in postsurgical macular oedema, ocular inflammatory disease, and choroidal melanoma.

Cyclo-oxygenase inhibitors in ophthalmology

Cyclo-oxygenase inhibitors, which are formulated as ophthalmic eyedrop preparations, have recently become commercially available for use by ophthalmologists in the United States to inhibit intraoperative miosis during cataract surgery and to prevent postoperative inflammation. In addition, they are available worldwide as ocular antiinflammatory drugs and are used in the prevention and treatment of pseudophakic and aphakic cystoid macular edema. Understanding the rationale behind the use of these agents requires an understanding of the pathophysiology of the cyclo-oxygenase inhibitors. In this review recent advances in laboratory and clinical science are emphasized. The role of COIs during and following surgery is examined.

Effects of steroids and immunosuppressive drugs on endotoxin-uveitis in rabbits

Anti-inflammatory actions of dexamethasone (DEXA), Cyclosporin A (CSA) and Rapamycin (RAPA) were assessed on uveitis induced by intravitreal E-coli Endotoxin (100ng) in rabbits at 24 hrs. In this model, endotoxin caused a breakdown of the blood-aqueous barrier (BAB) and polymorphonuclear neutrophils (PMN) infiltration into the aqueous humor (AH) and iris-ciliary body (ICB). Intramuscular (I.M.) DEXA (2mg/kg) but not topical DEXA (0.1% 6 x daily) inhibited AH leukocytes and protein level. However, both routes caused an inhibition of AH Prostaglandin E2 (PGE2) and Leukotriene B4 (LTB4). In the ICB, I.M. DEXA significantly inhibited PGE2 synthesis and myeloperoxidase (MPO) activity. I.M. CSA (25mg/kg) and I.M. RAPA (10mg/kg) inhibited the AH leukocytes and protein content and MPO activity in the ICB. RAPA also inhibited AH protein and eicosanoid (except AH LTB4) levels in both the AH and ICB. Interestingly, castor oil, a vehicle of CSA, also inhibited AH leukocytes and the release of PGE2 into AH and from ICB. In summary, systemic administration of DEXA and other immunosuppressive drugs CSA and RAPA significantly inhibited endotoxin-induced uveitis in rabbits.

Human retinal pigment epithelial cell cultures: phenotypic modulation by vitreous and macrophages

In proliferative vitreoretinopathy (PVR), retinal pigment epithelial (RPE) cells migrate into the vitreous, where they may acquire a fibroblast-like morphology. Such cells may eventually form contractile periretinal membranes, resulting in traction retinal detachment. Among the environmental influences that could cause this change in RPE phenotype, exposure to vitreous and to macrophages is most obvious, as macrophages are invariably found in epiretinal membranes and precede membrane formation in experimental traction retinal detachment. We initiated studies to define modulation of cultured RPE cell morphology by exposure to vitreous or to macrophage-conditioned media. Vitreous, serum, and albumin alone had no effect on the epithelial appearance of RPE cells in vitro. However, macrophage-conditioned media and vitreous-serum or vitreous-albumin mixtures induced a reversible fibroblast-like appearance in these cells. These findings show that macrophages produce a morphoplastic substance for RPE cells, and suggest that vitreous also contains a factor(s) that affects RPE cell shape, and that requires mediation by serum components.

Vitrectomy for chronic aphakic cystoid macular edema. Results of a national, collaborative, prospective, randomized investigation

A five-year (1979-1984) prospective, randomized, controlled, collaborative study was performed by 27 experienced vitrectomy surgeons in 15 medical centers on 136 surgically aphakic eyes without lens implants but with vitreous adherent to the corneoscleral wound and with chronic aphakic cystoid macular edema (ACME). One hundred fifteen eyes completed the entire course of investigation. The purpose of the study was twofold: to determine the effectiveness of vitrectomy in eliminating established ACME and to determine the natural history of this condition. Following criteria contained within the study protocol, 68 eyes were randomized to surgery (RAN-S) or control (RAN-C), and 47 eyes were observed in the long-term observation group (LTO). Twenty-one eyes were eliminated from the investigation for reasons stated in the text. The RAN-S group proved to have a significantly better visual course than the RAN-C group (P = less than 0.01). An analysis of the LTO group revealed that if central vision did not decline to a level of 20/80 or worse, 27% of the eyes had a chance of spontaneously improving to a level of 20/50 or better. However, if central vision declines to or beyond this point, spontaneous visual improvement to 20/50 or better only occurred in 8% of eyes. Also reported are other important clinical findings such as the role of systemic diseases in ACME, the incidence of vitreous traction on the macula, prognostic value of pre-surgical medical therapy, a comparison of limbal versus pars plana surgical approach, the timing of surgery, and the effectiveness of fluorescein angiography as an objective monitor of visual function.

Alterations in ocular and optic nerve blood flow during intraocular surgery in aspirin pretreated rabbits

The effect of intraocular surgery on ocular and optic nerve blood flow was determined in rabbits either untreated or pretreated with aspirin. Surgery was either extracapsular lens extraction through a 100 degrees corneal incision or a sham-operation in which a 45 degrees corneal incision was performed and the lens left in place. In both cases, the incisions were not sutured and the intraocular pressure remained zero for one hour. A (85Sr) radioactive microsphere technique was used to measure blood flow in the iris, scraped ciliary processes, retina, choroid, and optic nerve. In rabbits not receiving aspirin pretreatment, blood flow was statistically increased in all portions of the eye, except the retina and optic nerve, studied for sham-operated eyes, and in the iris and optic nerve in the lens extraction group. In rabbits pretreated with aspirin, blood flow remained at normal levels. These results are consistent with the hypothesis that prostaglandins released during ocular surgery cause increased ocular tissue blood flow.

Complications of intraocular lenses. A historical and histopathological review

Recent improvements in intraocular lens (IOL) design, manufacturing techniques, and surgical techniques have greatly reduced the incidence of complications following implantation, and many authors now consider IOL implantation to be among the most safe and effective major surgical procedures. However, adverse reactions are still seen--some as late sequelae of earlier IOL designs and implantation techniques and some as sequelae of more recent implantations using "state-of-the-art" lenses and surgical techniques. Complications may be due to various factors, including surgical technique, IOL design, or the inability of some eyes with preexisting disease to tolerate an implant. The authors trace the evolution of IOLs since Ridley's first implant, summarizing the modifications in lenses and surgical techniques that were made as complications were recognized. They then review the clinical and histopathological features of selected cases from more than 200 IOLs and/or globes removed due to IOL-related complications and studied in the University of Utah Ocular Pathology Laboratory. It is hoped that this review will provide insights into the pathogenesis of IOL complications, enhancing the current success of implant procedures and stimulating further basic and clinical research in this area.