Peter Kristian Kofoed

Insight into 144 patients with ocular vascular events during VEGF antagonist injections

Aim To record ocular vascular events following injections of vascular endothelium growth factor (VEGF) antagonists. Methods Collaborative multicenter case series (48 cases), literature reviews (32 cases), and reports to the FDA (64 cases) of patients that had vascular occlusions during anti-VEGF therapy were collected and analyzed. Results A total of 144 cases of ocular vascular events were identified, with these diagnosed a median of 15 days after anti-VEGF injection. The majority of patients had pre-existing risk factors for cardiovascular events and nine patients had a prior history of glaucoma. Mean visual acuity dropped by 6.4 lines with severe visual loss after injection to NLP (five eyes), LP (six eyes), and HM (two eyes). The overall risk of ocular vascular events following a VEGF antagonist injection was 0.108% in the general population and 2.61% in the diabetic population. Mean retinal arterial constriction after intravitreal bevacizumab in 13 eyes was 21% (standard deviation = 27%), and mean retinal venous constriction was 8% (standard deviation = 30%). Conclusion Ocular vascular events are rare during anti-VEGF therapy, but can lead to severe visual loss and may be caused by a number of factors including the vasoconstrictor effect of the drug, a post-injection rise of intraocular pressure, patient stress as a result of the procedure, and the patient’s natural history of underlying ocular or systemic diseases. The diabetic population appears to have a tendency towards ocular vascular occlusions.

Scotopic electrophysiology of the retina during transient hyperglycemia in type 2 diabetes.

PURPOSE To examine dark-adapted retinal function in subjects with type 2 diabetes during transient hyperglycemia. METHODS Twenty-four subjects with type 2 diabetes and minimal diabetic retinopathy were randomized to an oral glucose tolerance test (OGTT) or a fasting regimen. One study eye was kept in the dark-adapted state at all times. Full-field electroretinography (ffERG) and blood glucose measurements were performed at baseline and after 20, 80, 140, and 200 minutes. RESULTS Mean capillary glucose had increased 162% from the fasting baseline value when the concentration peaked in the OGTT group after 80 minutes (P < 0.0001). Concomitantly, rod b-wave amplitude had increased by 34% (P = 0.0007), whereas the a- and b-wave amplitudes of the standard combined rod-cone response had increased by 17% (P = 0.0013 and P = 0.0064). The dark-adapted 30-Hz flicker response was unaffected by hyperglycemia. The scotopic ffERG amplitudes rose and fell in phase with the glycemia. Implicit times did not change with the rise and fall in glycemia. CONCLUSIONS The change in scotopic signaling amplitude in the outer and middle layers of retina in subjects with diabetes was proportional to the change in capillary glucose. Cone amplitude was not influenced by hyperglycemia in this study.

Profound retinal ischaemia after ranibizumab administration in an eye with ocular ischaemic syndrome

Acta Ophthalmol. 2010: 88: 808–810

Transient monocular blindness precipitated by sexual intercourse

A 66-year-old man complained of recurrent transient monocular visual loss in his left eye during the climax of sexual intercourse. The patient had no past medical history related to cardiovascular disease or erectile dysfunction and did not take any medication. He smoked one pack of cigarettes per day and had done so for 25 years. The patient had no history of alcohol or substance abuse, and no family history of cardiovascular disease was reported. The symptoms started 2 months before the patient was first seen by us, recurring invariably during sexual intercourse, two or three times per week. Each attack of blindness lasted 1–2 min, consisting of monosymptomatic complete visual loss of rapid onset in the left eye only (no light perception). Vision remained normal in the fellow eye. The patient stated that each attack was followed by spontaneous complete visual recovery over a few minutes. Initial ophthalmological and neurological examinations elsewhere revealed no abnormal findings. Cerebral computed tomography was normal, whereas ultrasonography showed complete internal carotid …

Retinal Vessel Diameters in Relation to Hematocrit Variation during Acclimatization of Highlanders to Sea Level Altitude

PURPOSE To examine variations in retinal vessel diameters during acclimatization of native highlanders to normobaric normoxia at sea level. METHODS Fifteen healthy residents of the greater La Paz region in Bolivia (3600 m above sea level) were examined thrice over a 72-day period, after having traveled by airplane to Copenhagen, Denmark, near sea level. RESULTS In the study subjects, hematocrit decreased from 49.6% (day 2) to 45.9% (P = 0.0066, day 23) and 41.7% (P < 0.0001, day 72); from days 2 to 23, retinal vein diameter increased by 2.68% (P = 0.0079); whereas retinal artery and vein diameters were indistinguishable from baseline after 72 days. No funduscopic signs of retinopathy were observed. Arterial blood pressure remained stable throughout the study. CONCLUSIONS Although a 16% reduction in hematocrit occurred between days 2 and 72 after arrival at sea level, the only significant excursion observed was that the diameter of the veins was larger at day 23 than at days 2 and 72. Retinal vessel diameters demonstrated a wide homeostatic range during acclimatization-driven hematocrit variation.

Cone pathway function in relation to asymmetric carotid artery stenosis: correlation to blood pressure

Purpose: To examine retinal function in relation to retinal perfusion pressure in patients with carotid artery stenosis.

Delayed response of the retina after hyperbaric oxygen exposure.

Purpose:  To examine retinal electrophysiological function and retinal thickness in healthy eyes before and after hyperbaric oxygen (HBO) exposure.

Lens autofluorescence is not increased at high altitude.

Purpose:  To study the relation between ambient environmental ultraviolet radiation exposure and lens fluorescence.

Macular perfusion velocities in the ocular ischaemic syndrome

To assess retinal perfusion in eyes with unilateral ocular ischaemic syndrome (OIS) and to compare with control subjects.

Cone pathway function in relation to asymmetric carotid artery stenosis: correlation to blood pressure - author's reply.

Editor, W e congratulate Kofoed et al. (2012) for their study investigating the effects of asymmetric carotid artery stenosis on the functional [multifocal electroretinogram (mfERG)] and physiological [intraocular pressure (IOP), ocular perfusion pressure (OPP) and ophthalmic artery systolic blood pressure (OSP)] aspects of the eye and the correlations between these parameters. The authors performed some very meaningful statistics and found that higher degree of carotid artery stenosis was associated with lower P1 amplitudes and higher P1 ⁄N1 implicit times in mfERG. The authors also reported that mfERG amplitudes ⁄ implicit time differences between the eyes were not significantly correlated with IOP, OSP and OPP differences. These results imply that lower blood supply to the eye results in functional deterioration in cone functions, does not affect the IOP and is not associated with the changes in OSP and OPP. The authors studied on 26 eyes of 13 patients. So the statistical differences were investigated by using 13 variables. We know from a statistical point of view that small number of participants may mask statistical significance, which may in fact exist. In such circumstances, dividing the group into parts may explore the real effect. Second, the effects of the lower degrees of carotid artery stenosis on the eye may be tolerated by compensatory mechanisms; however, these compensatory mechanisms are difficult to halt the effects of higher degrees of carotid artery stenosis. For this reason, we kindly suggest to the authors to decrease the number of participants by extracting some patients with lower differences of percentages in carotid artery stenosis severity. For example, the authors may include only the patients with at least 60% differences in the severity of carotid artery stenosis, and then perform the correlation between the IOP, OPP, OSP and carotid artery stenosis severity and P1 ⁄N1 amplitudes and implicit times in mfERG. This statistical approach will cause to lessen the number of participants in the group, but will possibly increase the reliability of statistical difference.