Effect of Air Tamponade among Patients with Epiretinal Membranes and Intraretinal Cystoid Changes Undergoing Vitrectomy with Membrane Peeling - A Prospective Randomized Trial. / Effekt der Lufttamponade bei Patienten mit epiretinalen Membranen und intraretinalen zystoiden Veränderungen nach Vitrektomie mit Membrane Peeling ­ eine prospektive randomisierte Studie.

BACKGROUND: The effect of air tamponade among patients undergoing vitrectomy with membrane peeling for removal of epiretinal membranes (ERM) is controversially discussed. The aim of the present study was to analyze differences in outcomes between air tamponade and balanced salt solution (BSS) in a study population with preoperative intraretinal cystoid changes. PATIENTS AND METHODS: This randomized study included patients scheduled for pars plana vitrectomy with membrane peeling owing to ERM and intraretinal cystoid changes. Air tamponade or BSS at the end of surgery was applied according to preoperative randomization. Optical coherence tomography and best-corrected distance visual acuity (DCVA) measurements were performed before surgery, 5 days after surgery, and 3 months after surgery. RESULTS: From 96 patients included, 85 eyes had full follow-up and could be included for analysis. Median improvement of DCVA was + 16 EDTRS letters (IQR: 8 to 22) among patients with BSS, while it was + 13 EDTRS letters (IQR: 8 to 17) among patients with air tamponade. There was a trend for better improvement of DCVA when BSS was left at the end of surgery, compared to air tamponade, but not reaching statistical significance. CONCLUSIONS: There were no statistically significant differences concerning resorption of preoperative intraretinal cystoid changes, improvement of visual acuity, and final DVCA between air tamponade and BSS.

Visual Performance of Two Diffractive Trifocal Intraocular Lenses: A Randomized Trial.

PURPOSE: To compare two trifocal intraocular lenses (IOLs), the RayOne Trifocal RAO603F IOL (closed-loop haptic IOL; Rayner Intraocular Lenses Limited) and the AT Lisa tri 839 MP IOL (plate-haptic IOL; Carl Zeiss Meditec AG), concerning optical and capsular bag performance. METHODS: Patients scheduled for cataract surgery received either a closed-loop haptic IOL or a plate-haptic IOL in the first eye and the other IOL in the second eye. Three months postoperatively, autorefraction and subjective refraction, uncorrected and corrected distance visual acuity at 4 m, 80 cm, and 40 cm, an objective reading test (Salzburg Reading Desk; SRD Vision), a defocus curve, IOL tilt and decentration, a questionnaire about dysphotopsia, and grading of halos with a halometer were performed. RESULTS: Eighty-eight eyes of 44 patients were included. Visual acuity was comparable between both IOLs. The closed-loop haptic IOL performed better in the defocus curve at -1.50 diopters (D) (0.08 ± 0.10 vs 0.12 ± 0.09 logMAR; P < .01). The plate-haptic IOL had better contrast sensitivity without glare under mesopic and photopic conditions in miosis (P = .0018 and .002, respectively) and mydriasis (P = .017 and .003, respectively). Significant differences were found for less overall subjective disturbance (P = .047) and starbursts (P = .039) for the plate-haptic IOL, but not for the other positive dysphotopsia symptoms. CONCLUSIONS: Both trifocal IOLs delivered good and comparable visual function with low degrees of disturbing dysphotopsia. The closed-loop haptic IOL was slightly superior in the defocus curve, whereas the plate-haptic IOL was slightly superior concerning contrast sensitivity and positive dysphotopsia. [J Refract Surg. 2021;37(7):460-465.].

A pilot study to assess the effect of a three-month vitamin supplementation containing L-methylfolate on systemic homocysteine plasma concentrations and retinal blood flow in patients with diabetes.

Purpose: The aim of the present study was to investigate the effect of a three-month dietary supplementation with a methylfolate formulation on homocysteine plasma concentrations and ocular blood flow parameters in patients with diabetes. Methods: Twenty-four patients with diabetes received a dietary supplement (Oculofolin, Aprofol AG, Switzerland) containing 900 µg L­methylfolate (levomefolate calcium or [6S]-5-methyltetrahydrofolic acid, calcium salt), methylcobalamin, and other ingredients for three consecutive months. The patients' plasma homocysteine concentration and retinal blood flow were assessed at baseline and after three months of folate intake. Retinal blood flow was measured using a custom-built dual-beam Doppler optical coherence tomography (OCT) system. In addition, flicker-induced retinal vasodilatation was assessed by means of a commercially available dynamic vessel analyzer (IMEDOS, Jena, Germany). Results: Supplementation was well tolerated by all patients. After three months, plasma homocysteine concentration significantly decreased from 14.2 ± 9.3 to 9.6 ± 6.6 µmol/L (p < 0.001). In addition, a tendency toward an increased total retinal blood flow from 36.8 ± 12.9 to 39.2 ± 10.8 µl/min was observed, but this effect did not reach the level of significance (p = 0.11). Supplementation had no effect on retinal vessel diameter or flicker-induced vasodilatation. Conclusions: The present data show that a three-month intake of a dietary supplement containing methylfolate can significantly reduce blood homocysteine levels in patients with diabetes. This is of importance because higher homocysteine plasma levels have been found to be associated with an increased risk of vascular associated systemic diseases and eye diseases. Whether systemic methylfolate supplementation affects retinal perfusion must be studied in a larger population.

Changes in Retinal Blood Flow in Response to an Experimental Increase in IOP in Healthy Participants as Assessed With Doppler Optical Coherence Tomography.

Purpose: Blood flow autoregulation is an intrinsic mechanism of the healthy retinal vasculature to keep blood flow constant when ocular perfusion pressure (OPP) is changed. In the present study, we set out to investigate retinal blood flow in response to an experimental decrease in OPP in healthy participants using Doppler optical coherence tomography. Methods: Fifteen healthy participants aged between 22 and 31 years (mean, 27 ± 3 years) were included in the present open study. IOP was increased stepwise via the suction cup method to induce a decrease in OPP. Retinal blood flow in arteries and veins was assessed using a custom-built Doppler optical coherence tomography system and pressure-flow relationships were calculated to assess autoregulation. Results: Suction cup application induced a pronounced increase in IOP with a maximum value of 50.5 ± 8.0 mm Hg at the highest level of suction. Pressure-flow relationships revealed that blood flow was autoregulated until the OPP was decreased by approximately 21 mm Hg and started to decrease significantly when the OPP was reduced by 30 mm Hg. Retinal blood flow at the last suction period decreased at a maximum of -57.0 ± 22.3% and 65.2 ± 15.4% in retinal arteries and retinal veins, respectively. These changes in retinal blood flow were less pronounced than the decrease in OPP (-75.2 ± 19.2%), indicating retinal autoregulation. Conclusions: The results of the present study confirm that retinal blood flow is autoregulated in response to changes in the OPP. Doppler optical coherence tomography has the potential to become a clinical tool for the investigation of retinal blood flow autoregulation in the future, because of its ability to assess the blood velocities and diameter of the retinal vessels parallel and therefore also their blood flow in absolute values. (Clinicaltrials.gov number NCT03398616).

The Effect of Orally Administered Dronabinol on Optic Nerve Head Blood Flow in Healthy Subjects-A Randomized Clinical Trial.

It has been hypothesized that besides its intraocular pressure (IOP) lowering potential, tetrahydrocannabinol (THC) may also improve ocular hemodynamics. The aim of the present study was to investigate whether single oral administration of dronabinol, a synthetic THC, alters optic nerve head blood flow (ONHBF) and its regulation in healthy subjects. The study was carried out in a randomized, placebo-controlled, double-masked, two-way crossover design in 24 healthy subjects. For each study participant, 2 study days were scheduled, on which they either received capsules containing 5 mg dronabinol or placebo. ONHBF was measured with laser Doppler flowmetry at rest and while the study participants performed isometric exercise for 6 minutes to increase mean arterial blood pressure (MAP). This was repeated 1 hour after drug intake. Ocular perfusion pressure (OPP) was calculated as 2/3MAP-IOP. Dronabinol was well tolerated and no cannabinoid-related psychoactive effects were reported. Neither administration of dronabinol nor placebo had an effect on IOP, MAP, or OPP. In contrast, dronabinol significantly increased ONHBF at rest by 9.5 ± 8.1%, whereas placebo did not show a change in ONHBF (0.3 ± 7.4% vs. baseline, P < 0.001 between study days). Dronabinol did not alter the autoregulatory response of ONHBF to isometric exercise. In conclusion, the present data indicate that low-dose dronabinol increases ONHBF in healthy subjects without affecting IOP, OPP, or inducing psychoactive side effects. In addition, dronabinol does not alter the autoregulatory response of ONHBF to an experimental increase in OPP. Further studies are needed to investigate whether this effect can also be observed in patients with glaucoma.