Hironobu Ogasawara

Retinal Detachment after Cataract Surgery: Surgical Results

The authors studied the results obtained by the Retina Associates in 376 eyes of 361 patients operated on for retinal detachment associated with aphakia or pseudophakia with a postoperative follow-up of at least 6 months. All eyes underwent scleral buckling. The series included 103 eyes with aphakia, 17 eyes with iris-fixated intraocular lens, 111 eyes with anterior chamber (AC) IOL, and 145 eyes with posterior chamber (PC) IOL. The overall success rate for retinal detachment was 93%, without significant difference among the different groups. The aphakia and PC IOL groups had significantly higher prevalence (63% and 60%, respectively) of visual acuity equal to or better than 20/40 compared with the AC IOL group (33%). The prevalence of postoperative corneal edema in the AC IOL group was significantly higher than in the aphakia and PC IOL groups. Preoperative vitreous hemorrhage, large retinal breaks, posterior retinal breaks, total retinal detachment, proliferative vitreoretinopathy, and the need for performing a closed vitrectomy were significant factors in predicting ultimate failure.

Effect of Timolol on Human Retinal, Choroidal and Optic Nerve Head Circulation

In a double-masked, randomized, placebo-controlled study, we evaluated the effect of topical timolol maleate 0.5% on the retinal, choroidal, and optic nerve head circulation in 5 healthy volunteer subjects. Changes in the pulsatile component of choroidal blood flow (PCBF) were determined from measurements of the ocular pulse wave. Changes in the retinal arterial blood flow rate (RBF) and optic nerve head capillary blood speed (CBS) were determined by laser Doppler velocimetry and monochromatic photography. In timolol-treated eyes, PCBF decreased by 32 +/- 12% (p = 0.0007). Changes in RBF and CBS were not statistically significant. In the contralateral placebo-treated eyes, PCBF decreased by 15 +/- 8% (p = 0.006) and RBF increased by 18 +/- 10% (p = 0.002). The change in CBS was not statistically significant.

Retinal blood flow alterations associated with scleral buckling and encircling procedures.

The bidirectional laser Doppler technique and monochromatic photography were used to measure the absolute blood flow rate in the major temporal retinal arteries in seven patients following unilateral scleral buckling and encircling procedures, and in two patients before and after removal of scleral buckling elements. In the seven patients who had undergone uncomplicated scleral buckling procedures the arterial flow rates were on average 50% lower (p = 0.01) in the surgically treated eyes than in the contralateral eyes. Removal of scleral buckling elements in two patients produced increases of 73% and 44% in arterial blood flow rates.

Oscillatory Potentials and Permeability of the Blood-retinal Barrier in Noninsulin-dependent Diabetic Patients without Retinopathy

Electroretinography and vitreous fluorophotometry were performed in 36 eyes of 36 noninsulin-dependent diabetic patients and in 32 eyes of 32 healthy control subjects between the ages of 30 and 59 years. Fluorescein fundus angiograms showed no abnormalities in either group. Peak implicit time of the first deflection of the oscillatory potential, interpeak interval between the first and second deflections, and the sum of the amplitudes of the upward deflections were analyzed. Inward permeability of the blood-retinal barrier was calculated by vitreous fluorophotometry and computer simulation. The peak implicit time of the first deflection and the interpeak interval between the first and second deflections of the oscillatory potential were significantly longer in diabetic patients than in control subjects (P less than 0.01). No significant difference in inward permeability of the blood-retinal barrier existed between the two groups. These results indicate that a selective delay in the peak implicit time of the oscillatory potential (neurosensory retinal abnormality) may be present in noninsulin-dependent diabetic patients, representing retinal functional changes before changes in blood-retinal barrier permeability are apparent.

Comparison of short- and long-term effects of betaxolol and timolol on human retinal circulation.

Purpose To determine the short- and long-term effects of betaxolol and timolol on human retinal circulation.Methods In a double-masked, randomised, placebo-controlled study we evaluated the effects of both a one-drop application and a twice-daily 2-week application of either topical 0.5% betaxolol hydrochloride or topical 0.5% timolol maleate on the retinal circulation in 12 healthy volunteers. Laser Doppler velocimetry was used to detect changes in the retinal venous blood flow.Results In both betaxolol- and timolol-treated eyes, intraocular pressure decreased significantly compared with baseline values after both 90 min and 2 weeks. In betaxolol-treated eyes, retinal blood flow did not change significantly after 90 min, but increased significantly (14 ± 9%; p = 0.02) compared with baseline after 2 weeks. In timolol-treated eyes, retinal blood flow decreased significantly (18 ± 5%: p = 0.04) compared with baseline after 90 min, and also decreased significantly (14 ± 6%; p - 0.04) compared with baseline after 2 weeks.Conclusions Retinal blood flow increases as a long-term effect of betaxolol and decreases as both a short- and long-term effects of timolol.

Permeability of the blood-ocular barrier in adolescent and adult diabetic patients.

The permeability of the blood-ocular barrier was examined by fluorophotometry in adolescent and adult diabetic patients before the onset of retinopathy. The adolescent group consisted of 52 eyes of 52 insulin dependent diabetic patients aged 11 to 19 years and a control group of 10 eyes of 10 normal adolescents. The adult group consisted of 74 eyes of 74 non-insulin dependent diabetics and a control group of 30 eyes of 30 normal adults. The increase in lens autofluorescence in the adolescent diabetic patients compared with the controls was striking and showed a significant positive correlation (r = 0.79, p < 0.0001) with the duration of diabetes. Anterior chamber (AQ) values, an index of the permeability of the blood-aqueous barrier (BAB), increased in the adolescent diabetic patients compared with the controls and showed a significant positive correlation with glycosylated haemoglobin levels. No significant differences from the controls were observed regarding the permeability of the blood-retinal barrier (BRB). In the adult group there was no significant difference in either the permeability of the BRB or the AQ values between the diabetic and the control groups. Our results suggest that adolescent diabetic patients differ from adults in that BAB permeability is increased before the onset of retinopathy, suggesting that this is the cause of the striking increase in lens autofluorescence.

The use of scanning laser ophthalmoscope microperimetry to detect visual impairment caused by macular photocoagulation

BACKGROUND AND OBJECTIVE To demonstrate the effectiveness of scanning laser ophthalmoscope (SLO) microperimetry in detecting retinal sensitivity and in describing areas of unstable fixation following photocoagulation therapy. PATIENTS AND METHODS Two patients with iatrogenic vision loss resulting from photocoagulation therapy underwent a fundus examination, SLO microperimetry, and fluorescein angiography. One patient also underwent indocyanine green angiography. RESULTS Two types of visual acuity decrease--sudden-onset and late-onset--were demonstrated following macular photocoagulation, the former resulting from incorrect identification of the fixation point, and the latter from enlarging photocoagulation scars placed in close proximity to the fovea. In one case, SLO microperimetry detected dense scotoma corresponding to the patients symptoms and an unstable fixation point. In the other case, different retinal sensitivities were found in the photocoagulation scars. No differences were found with fluorescein angiography or indocyanine green angiography. CONCLUSION SLO microperimetry might be effective for quantitative assessment of retinal sensitivity in photocoagulation scars and for detecting fixation points and determining their stability.

RETINAL DETACHMENT AFTER CATARACT SURGERY: PREDISPOSING FACTORS

The authors studied the characteristics of 376 eyes of 361 patients with primary retinal detachment (RD) and surgical aphakia (103 eyes) or pseudophakia (273 eyes). Of the pseudophakic eyes, 17 had an iris-fixated intraocular lens (IOL), 111 had an anterior chamber (AC) IOL, and 145 had a posterior chamber (PC) IOL. Of the PC IOL cases, 48 (33%) had undergone YAG capsulotomy, and 46% of them developed RD within 6 months after capsulotomy. The frequency of no breaks found in pseudophakic RD (15%) was significantly higher than in RD with simple aphakia (5%). The most frequent reasons were incomplete fundus view due to a small pupil in the iris-fixated (83%) and the AC (44%) groups, and cloudiness of capsular remnants in the PC group (78%). In pseudophakic RD, sizable single tears, located more posteriorly than in RD with simple aphakia, were frequent. The authors speculate that in pseudophakic RD the retinal breaks may resemble those noted in phakic RD.

Ocular circulatory changes following scleral buckling procedures.

The effect of segmental scleral buckling (SB) on ocular circulation was evaluated by measurements of the ocular pulse amplitude (PA) and the ophthalmic artery pressure (OAP). In this study the OAP was defined as the intraocular pressure (IOP) at which the PA disappeared during increasing IOP. Twenty four patients with unilateral rhegmatogenous retinal detachment who underwent SB of varying extent were studied; the unoperated fellow eyes served as controls. Both the OAP and the ophthalmic perfusion pressures (OAP minus IOP) decreased significantly (p < 0.01) as the area of SB treatment increased. Follow-up measurements showed that the OAP was relatively lower up to 3 months postoperatively than after 3 months, and then remained stable. Our results indicated that SB affects the ocular pulse measurements and may decrease ocular blood flow because of decreased ophthalmic perfusion pressure, probably due to increased choroidal vascular resistance, and that the greater the extent of the SB treatment, the greater the possibility of decreased ocular blood flow.

Retinal Hemodynamics in Middle-Aged Normal Subjects

The laser Doppler technique and monochromatic photography were used to measure the total retinal blood flow, temporal/nasal differences in blood flow and the relationship between blood flow and vessel diameter in 5 healthy subjects, aged 54-58 years. Systemic blood pressure (BP) and intraocular pressure were also measured, and the retinal perfusion pressure was calculated. The measurements were compared to those previously obtained from a younger group of 7 healthy subjects, aged 25-38 years. Total retinal blood flow was 73 +/- 13 microliters/min in the middle-aged subjects and was not significantly different from the value measured in young subjects (80 +/- 12 microliters/min). Retinal perfusion pressure was significantly higher in the older subjects, primarily due to elevated systemic BP. The similarity in total flow between the two groups, even though the retinal perfusion pressures were higher in the older group, is an indication of an increased vascular resistance to flow. The increase may be an aging phenomenon or an indication of a well-functioning autoregulatory capacity in the retinal vasculature of the older subjects.