Ocular structure and function in an aged monkey with spontaneous diabetes mellitus.

Diabetes mellitus develops spontaneously in middle-aged, obese rhesus monkeys, thus making them a good model for examining the effects of co-morbid factors on the development of end-organ damage. Changes in structure and function in the eyes of one monkey who spontaneously developed type 2 diabetes are reported here. This animal had concomitant hypertension, high levels of triglycerides and serum cholesterol, and a low fraction of high-density lipoprotein. The eyes showed intraretinal hemorrhages and large areas of retinal capillary nonperfusion. Indo-cyanin green (ICG) angiography revealed a large area of non- or poorly perfused choriocapillaris in one eye, and immunohistochemistry showed loss of viable choriocapillaries in this region. Both basal laminar deposits and hard drusen were present on areas of Bruch's membrane adjacent to nonviable choriocapillaris. Blood flow via the nasal posterior ciliary arteries to this section of choroid was not detectable by color duplex Doppler ultrasound, indicating contribution of extraocular vascular disease to ischemia in this eye. There was a severe decline in number of photoreceptor inner and outer segments, and corresponding reductions in the multifocal electroretinogram (ERG), in the areas of choriocapillaris loss. The ganzfeld ERG indicated loss in both inner and outer retinal function. Much of the ganglion cell layer was absent throughout the retina, possibly reflecting the effect of diabetes as well as chronic open angle glaucoma; the latter diagnosis supported by elevated intraocular pressures and excavated optic disks. In summary, high resolution, enzyme histochemical and histopathological analyses of a diabetic hypertensive monkey retina and choroid after serial functional in vivo analyses have demonstrated the relationship between vascular dysfunction and visual function loss. Choroidal vascular dysfunction in both large and small vessels was associated with age-related macular degeneration-like changes in Bruch's membrane and photoreceptor degeneration.

Efficacy of transpupillary thermotherapy (TTT) in the treatment of occult subfoveal choroidal neovascularization in age-related macular degeneration.

PURPOSE: To determine the efficacy of transpupillary thermotherapy (TTT) in the treatment of occult subfoveal choroidal neovascularization in patients with age-related macular degeneration (ARMD). METHODS: We conducted a retrospective review of patients with ARMD treated with TTT from June, 1999 through July, 2000 at a retina referral practice. TTT was delivered through a slit-lamp using a modified diode laser at 810 nm wavelength and a spot size of 3 mm delivered at one location for a minimum of 60 seconds duration. Re-treatment was performed at 2-month intervals if indicated. RESULTS: 81 eyes of 77 patients were included in the study. Vision improved greater than one line Snellen in 18 eyes (22%), vision was stable within one line Snellen in 38 (47%), and worsened greater than one line Snellen in 25 (31%). Patients had a mean follow-up of 9 months. The average number of treatments was 1.37 (range 1 to 4). Pretreatment vision was less than or equal to 20/200 in 54% of eyes. CONCLUSIONS: Transpupillary thermotherapy may stabilize visual acuity in a majority of patients with occult subfoveal choroidal neovascularization secondary to ARMD. Proof of therapeutic benefit is best determined by a randomized clinical trial that is currently underway (TTT4CNV).

Transscleral infrared laser for retinal ablation without retinal visualization in an experimental model.

PURPOSE: To investigate whether transscleral diode laser can create retinal photocoagulation reliably without creating retinal holes under conditions simulating opaque media. METHODS: In New Zealand pigmented rabbits, optimal infrared diode laser power settings were determined, and transscleral retinal photocoagulation was then applied 4 mm and 6 mm from the limbus without retinal visualization. Transscleral testing was done using retina and cyclophotocoagulation probes placed directly on the sclera, on conjunctiva, and on silicone scleral buckles. RESULTS: A retina probe placed on the sclera achieved moderate retinal photocoagulation intensity in 75% of spots 4 mm from the limbus and in 50% of spots 6 mm from the limbus. Retinal holes were only formed when using the transscleral cyclophotocoagulation (TSCPC) probe. An association between burn intensity and the presence of conjunctiva was seen for the TSCPC probe (P = 0.0001) but not for the retina probe (P = 0.125). Photocoagulation spots did not exceed moderate intensity through any of the silicone scleral buckles tested. CONCLUSIONS: Transscleral infrared photocoagulation applied without retinal visualization did not cause retinal hole formation with a retina probe placed directly on conjunctiva, sclera, or scleral buckle material. A TSCPC probe created retinal holes when placed directly on sclera. A decrease in power was required for all treatments closer to the limbus.

Effects of intravitreal corticosteroids in the treatment of Bacillus cereus endophthalmitis.

OBJECTIVE: To investigate whether intravitreal corticosteroid therapy reduces the extent of inflammatory intraocular tissue damage caused by Bacillus cereus endophthalmitis. METHODS: New Zealand white rabbits were inoculated with 1 x 10(6) B cereus organisms and randomized to receive no treatment (control eyes; n=14), intravitreal vancomycin hydrochloride (n=13), or a combination of intravitreal vancomycin and dexamethasone sodium phosphate (n=13) after 24 hours. The eyes were examined and graded for clinical signs of infection and inflammation on days 7 and 14, followed by enucleation for histopathologic analysis. RESULTS: Both treated groups had significantly less clinical sequelae than controls on day 7. By day 14, eyes given combination treatment had significantly less clinically graded corneal (P=.03) and conjunctival (P=.007) inflammation than eyes treated with vancomycin. Histopathologic analysis revealed a significant decrease in inflammatory changes between all treated eyes and controls at day 14. The only statistically significant difference between eyes given combination treatment and eyes given vancomycin alone was in the retina (P=.03). CONCLUSIONS: Intravitreal corticosteroids may enhance the recovery from B cereus endophthalmitis when given in conjunction with intravitreal antibiotics. The beneficial effect of corticosteroids is noted clinically, but not histologically, by day 14 after single-dose treatment in rabbits. CLINICAL RELEVANCE: This study provides evidence that the use of intravitreal corticosteroids with antibiotics for the treatment of B cereus endophthalmitis may lead to an improvement compared with the use of antibiotics alone. Arch Ophthalmol. 2000;118:803-806

Penetrating eye injury in war.

The percentage of penetrating eye injuries in war has increased significantly in this century compared with the total number of combat injuries. With the increasing use of fragmentation weapons and possibly laser weapons on the battle-field in the future, the rate of eye injuries may exceed the 13% of the total military injuries found in Operations Desert Storm/Shield. During the Iran-Iraq War (1980-1988), eye injuries revealed that retained foreign bodies and posterior segment injuries have an improved prognosis in future military ophthalmic surgery as a result of modern diagnostic and treatment modalities. Compared with the increasing penetrating eye injuries on the battlefield, advances in ophthalmic surgery are insignificant. Eye armor, such as visors that flip up and down and protect the eyes from laser injury, needs to be developed. Similar eye protection is being developed in civilian sportswear. Penetrating eye injury in the civilian sector is becoming much closer to the military model and is now comparable for several reasons.

Inhibition of postvitrectomy fibrin using troxerutin.

PURPOSE: To evaluate the efficacy of intraocular infusion of troxerutin in the inhibition of fibrin formation after vitrectomy in a rabbit model. METHODS: Lensectomies and vitrectomies were performed in a masked fashion on seven eyes treated with a 10-mM infusion of troxerutin and on seven control eyes that received only a balanced salt solution infusion. Masked grading of intraocular fibrin formation and intravitreal hemorrhage was performed for 1 week. RESULTS: On postoperative days 1 and 2, the control group exhibited a greater mean fibrin index (MFI) percentage than the troxerutin-treated group (day 1, 27.7% versus 19.5% MFI; day 2, 14.5% versus 6.1% MFI, respectively). On postoperative day 3, both groups showed an MFI of 1.8%. On postoperative days 5 and 7, both groups showed only minimal presence of fibrin. Neither of the two groups had an increased rate of intraocular hemorrhage. CONCLUSIONS: Infusion of 10 mM troxerutin resulted in a relative decrease in the amount of fibrin produced without an increased risk of intraocular hemorrhage in treated eyes compared with controls, but the difference was not statistically significant. Further studies may be warranted to evaluate the optimal dose of troxerutin alone or a possible role for its use in conjunction with other drugs employing a different mechanism of action in the prevention of fibrin formation.

Macular complications associated with posterior staphyloma.

PURPOSE: To report macular abnormalities associated with posterior staphyloma in eyes with myopia. METHODS: In a retrospective study, we surveyed 116 eyes of 58 patients with myopic refractions. Myopic fundus abnormalities are related to clinically quantified posterior staphyloma formation. RESULTS: A posterior staphyloma was present in 88 (75.9%) of 116 eyes with myopic refractions of -3 diopters or more. Best-corrected visual acuity was decreased among eyes in all staphyloma grades. Eyes with the shallowest staphyloma depth (grade 1) displayed the largest drop in visual acuity as well as the greatest frequency of choroidal neovascular membranes and hemorrhages. A linear relationship was observed between staphyloma grade and conus formation (P = .001), retinal pigment epithelial defects (P = .0001), lacquer cracks (P = .0001), and chorioretinal atrophy (P = .001). All these variables were increased in staphylomatous eyes. A significant difference in means by staphyloma grade was observed for myopic refractive error (P = .001), axial length (P = .001), and best-corrected visual acuity (logMAR, P = .0001). CONCLUSIONS: There was an unexpected high frequency of choroidal neovascular membranes, hemorrhage, and poor best-corrected visual acuity in the lower staphyloma categories. This suggests that the development of a choroidal neovascular membrane requires relative preservation of the choriocapillaris as present in eyes with less advanced stages of posterior staphyloma formation.

Difficulties in excluding the diagnosis of retinoblastoma in cases of advanced Coats' disease: a clinicopathologic report.

We highlight the difficulty in differentiating Coats' disease from retinoblastoma. Two patients with bullous exudative retinal detachment and abnormal vessels are discussed. Histologic evaluation of the 5-year-old patient revealed retinoblastoma. The 1-year-old patient had Coats' disease by histologic identification. With this in mind, we suggest enucleation of such eyes if diagnostic uncertainty exists, since failure to treat retinoblastoma is a more serious error than enucleation of an eye with minimal function.