Relationship between intraocular pressure and primary open angle glaucoma among white and black Americans. The Baltimore Eye Survey

A detailed ocular examination, including perimetry, was conducted on 5308 black and white subjects aged 40 years and older in a population-based prevalence survey in east Baltimore, Md. Repeated, detailed examinations were carried out on selected subjects. Roughly half of all subjects with optic nerve damage from primary open angle glaucoma, regardless of race, were unaware that they had the condition. The average intraocular pressure (IOP) among black patients with glaucoma who were receiving treatment was virtually identical to that in those black patients who were not receiving treatment (median IOP, 20 mm Hg); treated eyes of white patients had a lower IOP than those eyes of white patients who were not receiving treatment (mean [+/- SD] IOP, 18.69 +/- 3.23 mm Hg vs 24.15 +/- 5.23 mm Hg; P less than .001). The risk of glaucomatous optic nerve damage increased with the height of the screening IOP, particularly at levels of 22 to 29 and 30 mm Hg and above (relative rate compared with IOP of 15 mm Hg or lower, 12.8 and 40.1 mm Hg, respectively). More than half of all glaucomatous eyes had a screening IOP below 21 mm Hg, whether these eyes were receiving treatment or not. The IOP in glaucomatous eyes tended to rise on follow-up, in contrast with nonglaucomatous eyes in which the IOP was as likely to rise as to fall. Results confirmed that IOP is an important factor in glaucoma, but did not support the traditional distinction between "normal" and "elevated" pressure, nor its corollaries, "low-tension" glaucoma and "high-tension" glaucoma.

Racial differences in the cause-specific prevalence of blindness in east Baltimore

BACKGROUND

Bilateral blindness unrelated to simple refractive error is twice as prevalent among blacks as among whites, although the difference narrows among the elderly. The reasons for this race- and age-related pattern are uncertain.

METHODS AND RESULTS

A randomly selected, stratified, multistage cluster sample of 2395 blacks and 2913 whites 40 years of age and older in East Baltimore underwent detailed ophthalmic examinations by a single team. We identified 64 subjects who were blind in both eyes. The leading causes of blindness were unoperated senile cataract (accounting for blindness in 27 of the total of 128 eyes), primary open-angle glaucoma (17 eyes), and age-related macular degeneration (16 eyes). Together, these three disorders accounted for 47 percent of all blindness in this sample. Unoperated cataract accounted for 27 percent of all blindness among blacks, among whom it was four times more common than among whites; whites were almost 50 percent more likely than blacks to have undergone cataract extraction before the age of 80 (P less than 0.002). Primary open-angle glaucoma accounted for 19 percent of all blindness among blacks; it was six times as frequent among blacks as among whites and began 10 years earlier, on average. By contrast, age-related macular degeneration resulting in blindness was limited to whites, among whom it was the leading cause of blindness (prevalence, 2.7 per 1000; 95 percent confidence interval, 1.2 to 5.4); it affected 3 percent of all white subjects 80 years of age or older.

CONCLUSIONS

The pattern of blindness in urban Baltimore appears to be different among blacks and whites. Whites are far more likely to have age-related macular degeneration, and blacks to have primary open-angle glaucoma. The high rate of unoperated cataracts among younger blacks and among elderly subjects of both races suggests that health services are underused. Half of all blindness in this urban population is probably preventable or reversible.

Risk factors for corneal graft failure and rejection in the collaborative corneal transplantation studies. Collaborative Corneal Transplantation Studies Research Group

PURPOSE

To evaluate comprehensively the magnitude of suspected risk factors for corneal graft failure from any cause, failure from rejection, and immunologic reaction in patients at high risk for graft failure after corneal transplantation.

METHODS

The records of the 457 participants in the Collaborative Corneal Transplantation Studies were reviewed. All participants had at least two quadrants of stromal vascularization and/or a history or previous graft rejection. Patients were followed for 2 to 5 years. Characteristics of the patient, study eye, donor, donor-recipient histocompatibility, and surgical procedure were examined for their association with the graft outcomes of failure from any cause, rejection failure, and immunologic reaction. Multivariate survival analysis techniques were used to estimate rates of graft outcome events and to estimate the magnitude of risk factors.

RESULTS

Many apparent risk factors did not maintain their association with graft outcomes after adjustment for other risk factors. Young recipient age, the number of previous grafts, history of previous anterior segment surgery, preoperative glaucoma, quadrants of anterior synechiae, quadrants of stromal vessels, a primary diagnosis of chemical burn, and blood group ABO incompatibility were among the strongest risk factors identified for graft failure. Donor and corneal preservation characteristics had little influence on graft outcome.

CONCLUSIONS

Risk of graft failure varies substantially, even within a high-risk population. The number of risk factors present should be considered by the patient and surgeon when contemplating transplantation and planning follow-up.

A population-based evaluation of glaucoma screening: the Baltimore Eye Survey

The Baltimore Eye Survey was a population-based survey conducted from January 1985 to November 1988 among residents of east Baltimore, Maryland, who were 40 years of age or older. A total of 5,308 black subjects and white subjects received a comprehensive screening examination for glaucoma including tonometry, visual fields, stereoscopic fundus photography, and a detailed medical and ophthalmic history. Based on a definitive examination, a diagnosis of glaucoma of any type was made for 196 persons. Tonometry, cup:disc ratio, and narrowest neuroretinal rim width were evaluated for their ability to correctly classify subjects into diseased or nondiseased states. There were no cutoff values at which these variables provided a reasonable balance of sensitivity and specificity, separately or in combination. Logistic regression models were fit that included demographic and other risk factors. Sensitivities and specificities were calculated for varying cutoff levels on the distribution of predicted probabilities. There was no cutoff for which reasonable sensitivity and specificity were obtained. The authors conclude that the effectiveness of current techniques for glaucoma screening is limited.

The cause-specific prevalence of visual impairment in an urban population. The Baltimore Eye Survey

BACKGROUND

Whereas population-based data on the causes of bilateral blindness have been reported, little information is available on the distribution of causes of central vision loss less severe than the criteria used to define legal blindness. This visual impairment is responsible for a high proportion of eye care service use and results in important reductions in functional status.

METHODS

Data from the Baltimore Eye Survey were used to estimate the cause-specific prevalence of visual impairment (best-corrected visual acuity worse than 20/40 but better than 20/200) among black and white residents of east Baltimore who were 40 years of age or older. Eligible subjects underwent a screening examination at a neighborhood location and, for those whose best-corrected visual acuity was less than 20/30, a definitive ophthalmologic examination at the Wilmer Eye Institute.

RESULTS

The prevalence of visual impairment was 2.7% in whites and 3.3% in blacks; the age-adjusted relative prevalence (B/W) was 1.75 (P = 0.01). The leading causes of visual impaired eyes were cataract (35.8%), age-related macular degeneration (14.2%), diabetic retinopathy (6.6%), glaucoma (4.7%), and other retinal disorders (7.3%). Cataract, diabetic retinopathy, and glaucoma were more common as a cause of visual impairment among blacks, whereas macular degeneration was more frequent among whites. More than 50% of all subjects had the potential for improvement in vision with appropriate surgical intervention.

CONCLUSION

Visual impairment is a prevalent condition among inner city adults 40 years of age or older. The distribution of causes suggests that improvements in the visual health of the population could be achieved with more effective delivery of efficacious ophthalmologic care.

Complications of semiflexible, closed-loop anterior chamber intraocular lenses

Anterior chamber intraocular lenses (IOLs) provided good visual rehabilitation of aphakia in a majority of patients. An increasing number of eyes with closed-loop, semiflexible anterior chamber implants are now being seen with decreased vision due to corneal edema and persistent cystoid macular edema. We evaluated 53 such eyes in 52 patients who presented with decreased vision one to 51 months (average, 15 months) after lens implantation. The most frequent lens implanted was the Surgidev Style 10 Leiske IOL. Surgery for IOL removal or exchange with or without penetrating keratoplasty was performed in 34 (64%) of 53 eyes; visual acuity recovery ranged from 20/20 to hand motions (average, 20/80). Despite clear corneal grafts in 24 (92%) of the 26 eyes that underwent corneal transplantation, visual acuity of 20/40 or better was obtained in only nine eyes (26%). Based on the intractable inflammatory sequelae associated with anterior chamber closed-loop IOLs, we strongly urge discontinuation of their use.

Extracapsular cataract extraction and posterior chamber lens implantation in eyes with preexisting glaucoma

Fifty eyes of 40 patients with glaucoma underwent extracapsular cataract extraction with posterior chamber lens implantation. Their visual results and early postoperative complications were compared with those of eyes in an age-matched group of patients without glaucoma after the same procedure. Substantial increases in early postoperative intraocular pressure (IOP) occurred in 62% of the glaucomatous eyes and in only 10% of the normal eyes. The level of best visual acuity was slightly worse (20/40) on average in the glaucomatous eyes than in the nonglaucomatous eyes (20/25). At six months after surgery, 82.5% of the nonfiltered glaucomatous eyes needed the same number of or additional glaucoma medications to maintain an IOP of less than 20 mm Hg. Ten of the glaucomatous eyes underwent trabeculectomy along with cataract surgery due to inadequate IOP control while the patient was receiving maximum medical therapy. Control was substantially improved, with 100% of these patients receiving the same number of or fewer medications at six months. By one year, only 30% of these patients required the same number of medications postoperatively as preoperatively, but all had IOP control.

Clinical experience with N-butyl cyanoacrylate (Nexacryl) tissue adhesive

BACKGROUND

To investigate the indications, outcomes, and complications of N-butyl cyanoacrylate tissue adhesive for ocular clinical use. This tissue adhesive is under investigation by the Food and Drug Administration.

METHODS

N-butyl cyanoacrylate was used as an investigational device on 44 patients at the authors' institution over a 2-year period. The charts of these patients were reviewed.

RESULTS

The indications for glue application included corneal perforation (19 eyes), descemetoceles (9 eyes), leaking filtering blebs (6 eyes), stromal thinning (5 eyes), wound leaks (4 eyes), and exposure keratopathy (1 eye). A bandage contact lens was used over the dried tissue adhesive in 38 of the 44 eyes. Length of glue adherence ranged from 1 to 660 days (mean, 72 days). Outcome was penetrating keratoplasty (19 eyes), no further intervention (14 eyes), enucleation (4 eyes), surgical revision of a filter (2 eyes), scleral patch graft (1 eye), conjunctival transplant (1 eye), failed tarsorrhaphy (1 eye), suturing of wound (1 eye), and a lamellar graft (1 eye). Vision improved in 52% (23/44) of eyes.

CONCLUSION

This tissue adhesive may soon be available to all ophthalmologists, and the authors' experience demonstrates that it is an effective method of temporary or permanent closure of an impending or frank perforation.

The efficacy and safety of combined trabeculectomy, cataract extraction, and intraocular lens implantation

The safety and efficacy of combined trabeculectomy, extracapsular cataract extraction (ECCE), and posterior chamber intraocular lens (PC IOL) implantation were evaluated by retrospectively analyzing 108 consecutive operations. Postoperatively, 89% of eyes achieved 20/40 or better visual acuity when preoperative macular and optic nerve diseases were excluded. Mean follow-up was 16.8 months. Intraocular pressure (IOP) control (less than or equal to 21 mmHg) was achieved in 92% of eyes; 57% required no medications. Capsulotomy (20%) and transient hyphema (15%) occurred significantly more often (P less than 0.001) than in a comparison group. These results suggest that the combined procedure gives excellent visual rehabilitation and IOP control in the majority of patients included in this analysis.

Posterior chamber intraocular lens implantation in the absence of capsular support

To avoid the complications associated with anterior chamber intraocular lenses (IOLs), we have developed a technique for the implantation of a posterior chamber IOL in the absence of capsular support. The IOL is secured in the ciliary sulcus by suturing the haptics to the sclera at the ciliary sulcus inferiorly and to the sclera or iris superiorly. We have used this technique for secondary IOL implantation in 16 contact lens-intolerant patients with aphakia with a mean follow-up of 9 months (range, 5 to 20 months) and in eight eyes at the time of IOL removal. All eyes with secondary implants had equal or improved vision postoperatively; none developed persistent angiographic cystoid macular edema. In the 8 patients with IOL exchange, visual acuity improved in five eyes, remained the same in two, and decreased two lines in one. Suturing of an IOL in the ciliary sulcus has enabled us to use a posterior chamber IOL in eyes without a posterior capsule when secondary IOL implantation or IOL exchange is indicated. Secondary posterior chamber IOL implantation is recommended only when satisfactory vision cannot be achieved with glasses or contact lenses, and further follow-up is needed before this procedure can be widely recommended.

Immune defense at the ocular surface

The ocular surface is constantly exposed to a wide array of microorganisms. The ability of the outer ocular system to recognize pathogens as foreign and eliminate them is critical to retain corneal transparency, hence preservation of sight. Therefore, a combination of mechanical, anatomical, and immunological defense mechanisms has evolved to protect the outer eye. These host defense mechanisms are classified as either a native, nonspecific defense or a specifically acquired immunological defense requiring previous exposure to an antigen and the development of specific immunity. Sight-threatening immunopathology with autologous cell damage also can take place after these reactions. This article discusses the innate and acquired corneal elements of the immune defense at the ocular surface. The relative roles of the various factors contributing to prevention of eye infection remain to be fully defined.

Calgranulin C has filariacidal and filariastatic activity

The calgranulins are a family of calcium- and zinc-binding proteins produced by neutrophils, monocytes, and other cells. Calgranulins are released during inflammatory responses and have antimicrobial activity. Recently, one of the calgranulins, human calgranulin C (CaGC), has been implicated as an important component of the host responses that limit the parasite burden during filarial nematode infections. The goal of this work was to test the hypothesis that human CaGC has biologic activity against filarial parasites. Brugia malayi microfilariae and adults were exposed in vitro to 0.75 to 100 nM recombinant human CaGC. Recombinant CaGC affected adult and larval parasites in a dose-dependent fashion. Microfilariae were more sensitive to the action of CaGC than were adult parasites. At high levels, CaGC was both macrofilariacidal and microfilariacidal. At lower levels, the percentage of parasites killed was dependent on the level of CaGC in the culture system. The larvae not killed had limited motility. The filariastatic effect of low-level CaGC was reversed when the CaGC was removed from the culture system. Immunohistochemical analysis demonstrated that human CaGC accumulated in the cells of the hypodermis-lateral chord of adult and larval parasites. The antifilarial activity of CaGC was not due to the sequestration of zinc. Thus, the cellular and molecular mechanisms that result in the production and release of CaGC in humans may play a key role in the regulation of filarial parasite numbers.

Natural history of corneal astigmatism after cataract surgery

Little information on the natural course of corneal astigmatism following cataract surgery exists. We report a prospective, computerized analysis of postoperative astigmatism, based on keratometry measurements, of 137 cases of extracapsular cataract extraction with intraocular lens implantation performed by one surgeon. No sutures were cut postoperatively. Surgery induced 1.44 diopters (D) of with-the-rule astigmatism at one month, which declined at a rate of 0.77 D and 0.35 D per month for the next two months, respectively, with a more gradual decline thereafter. The mean surgically induced astigmatism at the last postoperative visit ranged from 0.29 D at six months (minimum follow-up) to 1.23 D at 48 months; both were against-the-rule. Mean follow-up was 28.92 months. These findings may be technique specific and suggest that (1) corneal curvature continues to change slowly even two to four years postoperatively; (2) most patients develop against-the-rule astigmatism, thus more with-the-rule astigmatism is desirable in the early postoperative period; (3) selective suture removal is necessary only when significantly more than 3.00 D of surgically induced with-the-rule astigmatism is present.

Use of posterior chamber lenses in pseudophakic bullous keratopathy

The occurrence of pseudophakic bullous keratopathy following anterior chamber intraocular lens implantation is well documented. At the time of penetrating keratoplasty and anterior chamber intraocular lens removal, we attempt to reimplant a posterior chamber lens whenever possible because of the complications associated with anterior chamber lenses. We developed a technique to exchange an anterior chamber lens with a posterior chamber lens during penetrating keratoplasty. The intraocular lens loops are inserted in the ciliary sulcus and the optic is sutured to the iris.

Suture abscesses after penetrating keratoplasty

Eighteen suture abscesses that developed after penetrating keratoplasty in 15 patients were reviewed. The time from keratoplasty to the diagnosis of an abscess ranged from 1 to 53 months with a mean of 21.5 months. In 13 of the 18 cases, the patient was taking topical steroids at the time of diagnosis. All were culture-proven bacterial ulcers, except for one case that had a positive Gram's stain, but no growth on culture. The organisms cultured were Staphylococcus epidemidis (six eyes), Streptococcus pneumoniae (five eyes), Sta. aureus (four eyes), Str. viridans (two eyes), Klebsiella oxytoca (one eye), Serratia marcescens (one eye), Moraxella sp (one eye), and Escherichia coli (one eye). The offending suture was removed in all cases, and the eyes were treated with topical fortified antibiotics (cefazolin and tobramycin). After treatment, 67% (12 of 18 eyes) had clear grafts, 17% (three of 18 eyes) were scarred, and 16% (three of 19 eyes) had failed grafts. Intensive topical steroid therapy was used when a subsequent graft rejection developed. Retained sutures following corneal transplants can result in sight-threatening infections and should be considered for removal as soon as the wound is well healed.

Use of collagen corneal shields versus soft contact lenses to enhance penetration of topical tobramycin

We compared the corneal penetration in rabbits of topical tobramycin in the presence of collagen corneal shields and bandage soft contact lenses. A collagen corneal shield was placed on six albino rabbit eyes, while therapeutic soft contact lenses (61.4% poly-2-hydroxyethyl-methacrylate/38.6% water) were placed on six eyes. Four control eyes received no shield or contact lens. Topical tobramycin was applied to all 16 eyes every five minutes for six doses. Samples of aqueous humor were removed at 15 and 60 minutes following the last dose. Collagen corneal shields allowed a significant (P less than .05) increase in tobramycin penetration into the anterior chamber at 60 minutes compared with hydrophilic soft contact lenses or controls.

Topical ciprofloxacin treatment of Pseudomonas keratitis in rabbits

Ciprofloxacin is a new quinolone antibiotic that is highly active in vitro against Pseudomonas aeruginosa. A rabbit model of bacterial keratitis was used to assess the in vivo efficacy of topical ciprofloxacin. Albino rabbits received intrastromal injections of 5 X 10(2) aminoglycoside-resistant P aeruginosa organisms. At five hours after inoculation, ciprofloxacin (3 mg/mL) therapy was initiated (one drop every 30 minutes for 12 hours). Corneal tissue was then excised for bacterial colony counts. No organisms were recovered from ciprofloxacin-treated eyes, compared with an average of 3.1 X 10(7) organisms per milliliter recovered from untreated controls. This model suggests that topical ciprofloxacin may be clinically useful in the treatment of aminoglycoside-resistant P aeruginosa keratitis.

Neurotrophic factors, cytokines and stress increase expression of basic fibroblast growth factor in retinal pigmented epithelial cells

Basic fibroblast growth factor (bFGF) and FGF receptors have been localized to photoreceptors and retinal pigmented epithelium (RPE), but the function of bFGF in adult retina and RPE is unknown. Exogenous bFGF has a neuroprotective effect in retina and brain and its expression is increased in some neurons in response to cytokines or stress. In this study, we investigated the effect of light, other types of stress, neurotrophic factors, and cytokines on bFGF levels in cultured human RPE. Some agents that protect photoreceptors from the damaging effects of constant light, including brainderived neurotrophic factor (BDNF), ciliary neurotrophic factor, and interleukin-1 beta, increase bFGF mRNA levels in RPE cells. Intense light and exposure to oxidizing agents also increase bFGF mRNA levels in RPE cells and cycloheximide blocks the increase. An increase in bFGF protein levels was demonstrated by ELISA in RPE cell supernatants after incubation with BDNF or exposure to intense light or oxidizing agents. These data indicate that bFGF is modulated in RPE cells by stress and by agents that provide protection from stress and support the hypothesis that bFGF functions as a survival factor in the outer retina.

Infectious keratitis and cyanoacrylate adhesive

We studied three patients with infectious keratitis that occurred after cyanoacrylate gluing despite prophylactic antibiotic therapy. Two patients developed culture-positive bacterial ulcers, one caused by a methicillin-resistant Staphylococcus aureus and the other by Haemophilus influenzae. The third patient developed a fungal keratitis. Two patients required penetrating keratoplasty. Each infection and perforation was concealed by the opaqueness of the glue. The pain of the infectious ulcers may have been obscured by the ocular surface irritation and drying induced by glue. Tissue toxicity, microbial colonization, use of bandage lenses, and long-term broad-spectrum antibiotics may precipitate glue-related corneal infections. Masking of underlying infection and the development of resistant organisms should be considered when using this mode of therapy.

Excimer laser ablative treatment of microbial keratitis

The 193-nm excimer laser was used to ablate experimental septate fungal (Fusarium) and an atypical mycobacterial (Mycobacterium fortuitum) keratitis in an animal model. The infections were allowed to proceed for 24 and 72 hours. After incubation, ablation with a 193-nm excimer laser with 5.0-mm treatment zones was performed until all suppurative areas were treated. The corneas were excised, halved, homogenized, and plated. All cultures were negative in the 24-hour group. However, in those corneas in which the infections were allowed to proceed to 72 hours, post-treatment cultures were positive for both organisms. Histopathologic examination confirmed that 24-hour infections had been eradicated and that 72-hour infections had organisms present. Three of the eight eyes in the M. fortuitum group perforated during treatment, even though the treatment depth by computer preselection was only 150 microns. Excimer laser photoablation may be a useful technique to eradicate early, localized microbial infections. However, it is apparent that advanced infections with deep stromal involvement and suppuration cannot be eradicated using this technique. Because corneas may be perforated inadvertently during treatment, excimer laser treatment of infectious keratitis should be approached with caution and used for superficial and well circumscribed lesions.

Cytokine-induced calgranulin C expression in keratocytes

The authors have identified a corneal stromal protein (CO-Ag) that may be involved in the pathogenesis of Mooren's ulcer. The CO-Ag cDNA sequence is identical to that of human neutrophil calgranulin C (CaGC). This study sought to demonstrate expression of the CaGC gene in the human cornea and in corneal keratocytes after cytokine stimulation. In situ hybridization and immunohistochemistry were used to localize CaGC mRNA and protein in normal and diseased human corneas, including a specimen with Mooren's ulcer. Cultured bovine keratocytes were stimulated with IL-1 alpha or TNF-alpha, and reverse transcription polymerase chain reaction (RT-PCR) was performed to amplify CaGC cDNA from cytokine-stimulated keratocytes and unstimulated controls. Southern blotting verified the specificity of the RT-PCR amplification products. In situ hybridization detected human CaGC mRNA in the stroma of corneas with Fuchs' dystrophy, postinfection corneas, and a cornea with Mooren's ulcer. In cultured bovine keratocytes, peak levels of CaGC mRNA were reached 6 h after cytokine stimulation. Southern blots with an oligonucleotide probe specific for CaGC detected the RT-PCR products of expected sizes (273 bp) and confirmed that the amplified CO-Ag sequence was identical to that of CaGC. These studies are the first to demonstrate the presence of CaGC in the human cornea and the ability of stromal keratocytes to produce CaGC (CO-Ag). The up-regulation of CaGC gene expression by corneal keratocytes due to proinflammatory cytokines from trauma or inflammation may induce autoimmunity that ultimately results in Mooren's ulceration.

Therapeutic contact lenses

Therapeutic contact lenses are useful in a variety of ocular surface disorders. Their efficacy was evaluated in 40 consecutive patients presenting for therapeutic contact lens fitting for pain due to depressed surface disorders (14 patients), raised surface disorders (11 patients), corneal decompensation (7 patients), trauma (5 patients), and disorders of corneal wetting (3 patients). The therapeutic contact lens was successfully fit and worn, with achievement of the therapeutic objective in 37 of the 40 patients. Corneal wetting disorders and corneal decompensation require only intermediate-term contact lens wear. Thus, therapeutic contact lenses are usually effective for relief of pain due to corneal surface disorders.

Contact lenses for visual rehabilitation after corneal laceration repair

A contact lens fitting was tried after corneal laceration repair in 26 eyes. The mean patient age was 25 years; 22 eyes were aphakic and there were 23 males. Many patients had been referred for penetrating keratoplasty. Intact sutures in 13 eyes did not hinder contact lens fitting which was performed within 6 months in 12 cases. A contact lens was fit and successfully worn in 21 eyes (81%) and was fit in the remaining five patients, but not worn because of suboptimal vision (4 eyes) or an unsatisfactory fit (1 eye). Success rates were higher for small, peripheral lesions and in younger patients. Visual acuity was at least 20/30 in 12 patients and follow-up averaged 10.1 months. A contact lens can usually be fit after corneal lacerations, despite aphakia, with good visual results, thereby avoiding penetrating keratoplasty and intraocular lens implantation.

Spontaneous corneal perforation in a patient with unusual unilateral pellucid marginal degeneration

A 56-year-old man presented with acute loss of vision and tearing in his left eye. Slitlamp examination demonstrated peripheral corneal edema extending between the 2 and 6 o'clock positions as well as a perforation located inferiorly. The right eye was unremarkable. An emergent crescentic lamellar keratoplasty was performed. The patch graft remained clear during the 30-month follow-up, and visual acuity improved significantly. No changes occurred in the right eye. This case represents an unusual, unilateral corneal ectatic disorder, most likely pellucid marginal degeneration.

Light-induced deposits in Bruch's membrane of protoporphyric mice

Photosensitization of choriocapillary endothelium with blood-borne photosensitizers, such as protoporphyrin IX, has been proposed as a mechanism for the choriocapillary sclerosis and Bruch's membrane deposits seen in age-related macular degeneration. Utilizing a mouse model of protoporphyria with approximately a 10-fold increase in protoporphyrin IX level and exposure to blue light (14 microW/cm2; bandwidth, 390 to 430 nm), a time- and light-dependent increase in choriocapillary and sub-retinal pigment epithelium basal laminar-like deposits could be demonstrated at 7 months by transmission electron microscopy. Thickening of the choriocapillary endothelial basement membrane with a homogeneous electron-dense material was first noted in protoporphyric mice exposed to blue light for 13 weeks. At 28 weeks the experimental animals exhibited a thick band of homogeneous deposits at the level of the choriocapillary basement membrane and electron-dense fibrillogranular deposits of varying sizes along the inner aspect of Bruch's membrane, with fibrils measuring up to 16 nm, with a periodicity of 13 nm. These deposits contributed to an overall thickening of Bruch's membrane with narrowing of the choriocapillaris. The morphologic appearance and localization of these deposits within Bruch's membrane of this animal model are similar to previously described deposits noted in the aging Bruch's membrane prior to the development of age-related macular degeneration.