Stephen R. Waltman

A fluorophotometric study of the effect of topical timolol on aqueous humor dynamics.

Abstract A modification of the fluorophotometric method of Jones and Maurice is described and used to measure the aqueous flow coefficient. The method was used to measure the effect of topical timolol on aqueous humor dynamics in 15 human subjects. It was found that the acute decrease in intraocular pressure caused by timolol can be explained entirely by its effect on the aqueous flow. The mean aqueous flow coefficient in the timolol treated eye was found to be 0·0126 min −1 before timolol, and 0·0067 min −1 after timolol. A small effect on the aqueous flow coefficient of the untreated eye was also observed.

The natural history of retinopathy in insulin-dependent juvenile-onset diabetes

We determined the cross-sectional natural history of retinopathy by prospective study of 461 insulin-dependent juvenile-onset diabetics. In so doing, we compared the sensitivity of ophthalmoscopy, photography, and fluorescein angiography in detecting retinopathy. Photography was far more reliable than ophthalmoscopy in detecting early retinopathy and equivalent to angiography. Retinopathy was not present at diagnosis of diabetes. After a lag period, the prevalence of retinopathy rose in sigmoidal fashion, reaching 50% at just over seven years duration, and asymptotically approaching 90% at 17--50 years. Proliferative retinopathy was first seen at 13 years duration, and its prevalence rose to 26% at 26--50 years. From the natural history we computed the dimensions of a proposed clinical trial to test the effect of tight metabolic control in prevention of retinopathy.

Quantitative vitreous fluorophotometry. A sensitive technique for measuring early breakdown of the blood-retinal barrier in young diabetic patients.

Vitreous and aqueous humor fluorescein concentrations were measured one hour after graded intravenous fluorescein was given to 20 juvenile diabetics, ages 20 to 40, with and without ret-inopathy, and to 12 controls of similar age. Vitreous fluorescein concentrations were significantly higher in diabetics, indicating breakdown of the blood-retinal barrier. Mean vitreous fluorescein values were 10.66 ± 0.65 for the diabetics and 4.28 ± 0.37 ng./ml. for the controls. Breakdown of the blood-retinal barrier was also confirmed in diabetics under the age of 20 without retinopathy. The blood-aqueous barrier was similarly altered in diabetics. Vitreous fluorophotometry quantitatively measures breakdown of the blood-retinal barrier, possibly the earliest detectable ocular vascular abnormality in juvenile diabetic patients.

Central Corneal Endothelial Cell Density and Central Corneal Thickness in Ocular Hypertension and Primary Open-Angle Glaucoma

In order to assess the effect of increased intraocular pressure on the corneal endothelium, we classified 254 patients into four groups: Group 1, those with normal intraocular pressures; Group 2, those with untreated ocular hypertension; Group 3, those with treated ocular hypertension; and Group 4, those with primary open-angle glaucoma. One eye of each patient underwent specular microscopy and pachymetry. The eyes in the four groups did not differ significantly as to central corneal endothelial cell density or central corneal thickness. These measurements were not related to sex, race, or intraocular pressure (P greater than .12 in all cases). Increasing age was associated with a decrease in central corneal endothelial cell density (P = .0001), but was not associated with a change in central corneal thickness (P = .22). There was no significant relationship between the use of topical ocular hypotensive medications and central corneal endothelial cell density (P = .38) or central corneal thickness (P = .07) in patients with ocular hypertension or primary open-angle glaucoma. Neither uncomplicated peripheral iridectomy nor trabeculectomy produced significant changes when preoperative measurements were compared to measurements made 12 weeks postoperatively (P greater than .30 in all cases). Two eyes with flat anterior chambers following trabeculectomy had substantial decreases in central corneal endothelial cell density.

Reversal of neuropathic and gastrointestinal complications related to diabetes mellitus in adolescents with improved metabolic control

Two adolescents with insulin-dependent diabetes mellitus developed unusually severe diabetic neuropathy which responded to intensive measures to achieve improved metabolic control. Employing home blood glucose monitoring and either frequent insulin injections or a portable insulin infusion pump, painful peripheral neuropathy and autonomic gastrointestinal neuropathy improved after five and 12 months of therapy, respectively. During this period of time, abnormal ocular fluorophotometry, an early change in the eye of diabetic patients, also returned to normal. These patients demonstrate the reversibility of unusually severe neuropathy and early ocular changes in adolescents with diabetes when treated with intensive measures designed to improve metabolic control.

Spontaneous detachment of Descemet's membrane

Detachment of Descemets membrane is an unusual cause of postoperative corneal edema. The typical detachment is small and usually limited to the area near the limbal wound. These peripheral detachments usually heal without sequelae as endothelium spreads over the area and secretes a new Descemets membrane. We report an unusual case of spontaneous, extensive central separation of Descemets membrane occurring 3 weeks following uncomplicated extracapsular cataract extraction with posterior chamber lens implant. Attempted reattachment of the membrane with intracameral air was only partially successful, but 12 weeks later the detachment spontaneously resolved with recovery of vision to 20/30. An anatomic predisposition may be implicated, because the fellow eye exhibits the diffuse thickening of Descemets membrane. Descemets detachment is a rare but potentially reversible cause of corneal edema following cataract surgery and should not be confused with early-onset pseudophakic bullous keratopathy.

Quantitative Vitreous Fluorophotometry in Insulin-treated Cystic Fibrosis Patients

A series of 22 patients with cystic fibrosis (CF) of similar clinical severity (9 with normal carbohydrate tolerance and 13 with insulin-treated fasting hyperglycemia) was examined with quantitative vitreous fluorophotometry. All of the CF patients studied had normal fundi on ophthalmoscopy, fundus photographs, and fluorescein angiography. Mean vitreous fluorescein concentration in the CF patients whose hyperglycemia was treated with insulin (11.79 ng/ml) was significantly higher than in CF patients with normal carbohydrate tolerance (6.98 ng/ml, P < 0.005). Thus, CF patients with fasting hyperglycemia demonstrate a breakdown of the bloodretinal barrier. When CF patients with fasting hyperglycemia were compared with age- and sex-matched type I diabetics, there was no significant difference in mean vitreous fluorescein accumulation. Thus, breakdown of the blood-retinal barrier, one of the earliest detectable functional abnormalities that may be associated with the microangiopathy of diabetes mellitus, also occurs with equal frequency and severity in the diabetes secondary to pancreatic fibrosis associated with CF.

Comparison of Intraocular Irrigating Solutions in Pars Plana Vitrectomy

A prospective, randomized, masked clinical study was conducted to examine the effects of pars plana vitrectomy on the corneal endothelium comparing Balanced Salt Solution (BSS) to BSS-Plus as an intraocular irrigating solution. Seventy-one patients were followed for at least six months. A significant 6.9% decrease in endothelial cell density was observed among all patients at six months postoperatively, compared to preoperative values, using the contralateral eye as a control. However, no significant difference in endothelial cell loss was found between BSS and BSS-Plus eyes. Both aphakic eyes and those undergoing lensectomy (with vitrectomy) showed a significantly greater reduction of endothelial cell density at six months compared to phakic eyes. No significant difference in corneal thickness was observed at six months postoperatively compared to preoperative values. For the one-year duration of our study BSS was as efficacious in preserving the integrity of the corneal endothelium as was BSS-Plus.

Aphakic Keratoplasty: Visual Acuity and Optical Errors

Sixty-four consecutive patients with aphakic penetrating keratoplasty and penetrating keratoplasty combined with intracapsular cataract extraction were reviewed in a prospective fashion with a minimum of a one-year follow-up. Five were lost to follow-up. There were seven graft failures at the end of one year. Five of these were from 11 patients who underwent second operations because of failed grafts. Visual acuity was 20/80 or better in 29 of the patients. Pathology accounted for decreased visual acuity in all of those with visual acuity less then 20/80. Problems wre macular degeneration in 11 of the 23 patients with poor visual acuity (48%); marked cystoid macular edema in four patients (17%), advanced glaucoma in three patients (13%) and amblyopia in three patients (13%). Graft size had no significant effect on visual acuity. In terms of the final refractive error and astigmatism, there were no significant differences seen in those in whom a larger donor was used compared with those in whom a donor the same size as the recipient opening was used. Aphakic penetrating keratoplasty has shown outstanding technical success with poor visual acuity representing a difficulty in screening for non-corneal pathology. With an otherwise normal eye, the chances for excellent optical success are very good at the present time with modern techniques in aphakic penetrating keratoplasty.

Vitreous Fluorophotometry in Adult-Onset Diabetes Mellitus

We studied the breakdown of the blood-retinal barrier in 83 patients with adult-onset diabetes mellitus, by using vitreous fluorophotometry. The patients were in good stable metabolic control and were receiving injectible insulin or oral hypoglycemic agents. Vitreous fluorophotometry readings were abnormally high but similar in both groups of patients, and no significant differences were found between those with and those without early background diabetic retinopathy. Significantly more patients taking oral agents were hypertensive, and significantly fewer of these patients had background retinopathy.