William H. Knobloch

Photocoagulation Treatment of Proliferative Diabetic Retinopathy: The Second Report of Diabetic Retinopathy Study Findings

Data from the Diabetic Retinopathy Study (DRS) show that photocoagulad inhibited the progression of retinopathy. These beneficial effects were noted to some degree in all those stages of diabetic retinopathy which were included in the Study. Some deleterious effects of treatment were also found, including losses of visual acuity and constriction of peripheral visual field. The risk of these harmful effects was considered acceptable in eyes with retinopathy in the moderate or severe retinopathy in the moderate or severe proliferative stage when the risk of severe visual loss without treatment was great. In early proliferative or severe nonproliferative retinopathy, when the risk of severe visual loss without treatment was less, the risks of harmful treatment effects assumed greater importance. In these earlier stages, DRS findings have not led to a clear choice between prompt treatment and deferral of treatment unless and until progression to a more severe stage occurs.

Progression of Diabetic Retinopathy after Pancreas Transplantation for Insulin-Dependent Diabetes Mellitus

We studied the effect of successful pancreas transplantation and consequent normoglycemia (mean total hemoglobin A1, 7.0 percent; range, 5.8 to 8.3) on visual function and diabetic retinopathy in 22 patients with Type I diabetes mellitus (study group). Sixteen similar patients in whom pancreas transplantation had been unsuccessful (mean total hemoglobin A1, 12.0 percent; range, 8.0 to 18.0) served as a control group. The majority of patients in both groups had advanced proliferative retinopathy. At a mean follow-up of 24 months we found no significant difference between the groups in the rate of progression of retinopathy, expressed as a score. Success of the transplantation did not prevent progression of retinopathy across the range of retinopathy studied. Progressive retinopathy was observed more commonly in patients with low retinopathy scores (nonproliferative or mild proliferative retinopathy) at base line in both the study group (13 of 17 eyes, or 76 percent) and the control group (7 of 12 eyes, or 58 percent). Further analysis suggested the possibility that after three years of euglycemia, the study group had less deterioration than the control group, particularly in eyes with advanced retinopathy. We observed no difference in the rate of loss of vision between the two groups. This study provides evidence that pancreas transplantation and subsequent normoglycemia neither reverse nor prevent the progression of diabetic retinopathy.

Treatment of Cytomegalovirus Retinitis with Intravitreal Ganciclovir: Long-term Results

Long-term management of cytomegalovirus (CMV) retinitis by intravitreal injection of ganciclovir was evaluated in ten patients with acquired immune deficiency syndrome (AIDS). Patients were unable to tolerate systemic ganciclovir because of severe neutropenia (8 cases), catheter-induced sepsis (1 case), or the need to continue therapy for human immunodeficiency virus (HIV) with zidovudine (ZDV) (1 case). All patients had a favorable response to initial treatment. Cytomegalovirus retinitis progressed in four fellow eyes in which treatment was deferred. Vision improved or remained stable in all but one eye. Patients were followed for a mean of 4 months and received an average of 16.6 intravitreal injections in each eye. Relapse occurred late in the course while on maintenance treatment in five eyes (33%). There was no evidence of toxicity from repeated intravitreal injections. Treatment was very well tolerated. The only severe complication in a total of 249 injections was a single case of Staphylococcus epidermidis endophthalmitis which responded to intravitreal antibiotic treatment. Intravitreal ganciclovir is an effective alternative to systemic ganciclovir in those patients with severe neutropenia and in those patients who desire to remain on systemic ZDV.

Ocular Perforation Following Retrobulbar Anesthesia for Retinal Detachment Surgery

We encountered three examples of the perforation of the globe by the retrobulbar needle in a series of 4,000 patients who had undergone retinal reattachment surgery with local anesthesia. The presence of significant myopia was a contributing factor in all three cases. We managed the perforation site through the detached retina with cryopexy and external tamponade, and we treated perforations through the attached retinas either with cryopexy at surgery or photocoagulation postoperatively.

Hermansky-Pudlak syndrome: Ophthalmic findings

Prospective ophthalmic evaluation was performed in 20 individuals with Hermansky-Pudlak syndrome, a type of oculocutaneous albinism with an associated deficiency of dense bodies in platelets. The extent of visual impairment and the possible relationship to the degree of hypopigmentation were studied. All patients showed nystagmus, visual acuity ranged from 20/60 to 20/400, and correction of refractive error provided a mild improvement in vision. Iris pigmentation varied in amount and did not correlate with the visual acuity measurement. Foveal hypoplasia was found in all patients, but variability in macular transparency and vascular architecture was noted. Visual-evoked potentials performed in 11 patients demonstrated excessive decussation of optic fibers. Recognition of this form of oculocutaneous albinism is important because of the associated pulmonary, gastrointestinal, renal, and cardiac manifestations of Hermansky-Pudlak syndrome.

Timing of vitrectomy for active proliferative diabetic retinopathy.

Eyes with active proliferative diabetic retinopathy with dense sub-hyaloid hemorrhage and significant visual loss represent an appropriate indication for prompt vitrectomy. Twenty-six such eyes in 22 patients were operated. The results are compared to 49 diabetic eyes undergoing vitrectomy for other complications of diabetic retinopathy. The results demonstrated both an improved anatomic success rate (85% compared to 73%) and a higher rate of reading visual function (54% compared to 18%) in the early vitrectomy group, substantiating the study hypothesis.

Histocompatibility Antigen Frequencies in Diabetic Retinopathy

We studied the histocompatibility antigens A and B in 300 insulin-dependent diabetics: 200 had proliferative retinopathy and 100 did not. The two groups were matched for known duration of diabetes and other clinical features. In both groups the frequencies of HLA-B8, HLA-B18, and HLA-B8/HLA-B15 were significantly higher, and those of HLA-B7 and HLA-B12 were significantly lower than in healthy controls. The patients with proliferative retinopathy were significantly less often positive for HLA-B7 (X2 = 10.0; Pc < .03) than patients with nonproliferative retinopathy. When both groups were stratified for age at diagnosis, there were additional differences. HLA-B15 was significantly more frequent in the proliferative retinopathy group with age at diagnosis between 15 and 40 years (nonproliferative retinopathy = 16.4%; proliferative retinopathy = 39.4%; X2 = 7.89, Pc < .03; relative risk = 3.32) and HLA-B7 significantly less frequent (nonproliferative retinopathy = 23.6%; proliferative retinopathy = 5.6%; X2 = 8.0, Pc < .03; relative risk = 0.19). These differences in histocompatibility frequencies between patients with and without proliferative retinopathy indicate a genetic contribution to diabetic retinopathy.

Vitrectomy for Double Penetrating Ocular Injuries

During the five-year period from 1977 to 1982, 15 consecutive patients with double penetrating ocular injuries were treated at the University of Minnesota. The 13 males and two females ranged in age from 5 to 38 years. Four patients had bilateral involvement. Vitrectomy techniques were used to stabilize the eyes and prevent or treat retinal detachment in 18 eyes. One eye was enucleated. Anatomic success was achieved in 11 eyes and visual success (visual acuity of 5/200 or better) in ten eyes. Surgical success was related to initial visual acuity, extent of vitreous hemorrhage, and the ability of the surgeon to excise completely the vitreous from the circumference of the exit wound.

Predicting Visual Acuity in Children With Colobomas Involving the Optic Nerve

BACKGROUND This study evaluates the relationship to visual acuity of four ophthalmoscopic features of colobomas involving the optic nerve. The goal was to identify those features that could predict potential visual acuity of children with these colobomas. METHODS Fundus photographs of 23 eyes with colobomas involving the optic nerve met the entry criteria and were evaluated by two masked observers. The following features were evaluated: coloboma size, optic nerve color, foveal development, and subfoveal retinal pigment epithelial changes. Simple linear regression was used to identify the feature that most closely correlated with visual acuity. Refractive status was assessed by cycloplegic refraction. RESULTS The only component that correlated with the development of good visual acuity was the degree of foveal involvement by the optic nerve coloboma (P = .002, R = 0.8). Significant refractive error and anisometropia were common in patients with colobomas involving the optic nerve. CONCLUSION Central visual acuity in children born with colobomas involving the optic nerve correlates with the development of normal foveal anatomy, regardless of the size of the coloboma, the color of the optic nerve, or the presence of subfoveal pigmentary changes. Because refractive error is common, these children should receive an accurate refraction and amblyopia treatment.

Idiopathic retinal dialysis.

Idiopathic retinal dialyses accounted for 1.8% of 1,789 eyes with rhegmatogenous retinal detachments diagnosed in two institutions over the 6-year period from 1972 through 1977. These detachments characteristically occur in the inferotemporal quadrant of young adult eyes and often are associated with demarcation lines, retinal cysts, peripheral microcystoid degeneration, and yellow-white vitreous opacities. This study provides additional evidence that a distinct type of retinal detachment secondary to nontraumatic retinal dialyses exists. The authors believe that these dialyses probably are secondary to a developmental abnormality of the inferotemporal periphery of the retina and vitreous base. Trauma may precipitate these dialyses but is not the primary cause.